1
|
Lynn AM, Sullivan LL, Galen C. The cost of self-promotion: ecological and demographic implications of the mentor effect in natural plant populations. THE NEW PHYTOLOGIST 2023; 237:1418-1431. [PMID: 36412063 DOI: 10.1111/nph.18629] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
Under the mentor effect, compatible heterospecific pollen transfer induces self-pollen germination in otherwise self-incompatible plants. The mentor effect could be considered a novel mode of reproductive interference if it negatively impacts fitness. Yet to date, this phenomenon has predominately been investigated under experimental conditions rather than in situ. We address this gap in natural populations of the self-incompatible native dandelion, Taraxacum ceratophorum, where selfing only occurs in association with hybridization from exotic Taraxacum officinale. We tested whether self-fertilization rate increases in the hybrid zone, as predicted due to the mentor effect. Using results from these investigations, we created an exponential growth model to estimate the potential demographic impacts of the mentor effect on T. ceratophorum population growth. Our results demonstrate that the strength of the mentor effect in Taraxacum depends on the prevalence of pollinator-mediated outcross pollen deposition rather than self-pollination. Demographic models suggest that reduced outcrossing in T. ceratophorum under exotic invasion could negatively impact population growth through inbreeding depression. We demonstrate the mentor effect is rare in natural populations of T. ceratophorum due to masking by early life cycle inbreeding depression, prevalent outcrossing, and ovule usurpation by heterospecific pollen.
Collapse
Affiliation(s)
- Austin M Lynn
- Department of Oceanography and Coastal Sciences, Louisiana State University, 3173 Energy, Coast, and Environment Building, Baton Rouge, LA, 70803, USA
| | - Lauren L Sullivan
- Department of Plant Biology, Michigan State University, 612 Wilson Road, Room 368, East Lansing, MI, 48824, USA
| | - Candace Galen
- Division of Biological Sciences, University of Missouri, 105 Tucker Hall, Columbia, MO, 65211, USA
| |
Collapse
|
2
|
Fei CH, Tang SS, Shang SH, Dai J, Wang XY, Wang S, Liu WQ, Wang XF. Conspecific pollen advantage mediated by the extragynoecial compitum and its potential to resist interspecific reproductive interference between two Sagittaria species. FRONTIERS IN PLANT SCIENCE 2022; 13:956193. [PMID: 35937372 PMCID: PMC9354020 DOI: 10.3389/fpls.2022.956193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
The extragynoecial compitum formed by the incomplete fusion of carpel margins, while allowing intercarpellary growth of pollen tubes in apocarpous angiosperms, may also increase the risk of reproductive interference caused by heterospecific pollen (HP) deposition. In Sagittaria, congeneric HP tubes grow via different paths and enter the ovules later than conspecific pollen (CP) tubes. However, it is unclear how the growth advantage of the CP tube helps ensure reproductive success when HP is deposited on the stigmas. We performed molecular characterization of interspecies-pollinated seeds to examine the consequences of interspecific pollen deposition between Sagittaria pygmaea and S. trifolia. We also conducted CP-HP (1:1) mixed pollination and delayed CP pollination treatments to explore the seed-siring abilities of CP and HP. Our results showed that although HP could trigger the development of fruits, the interspecies-pollinated seeds contained partially developed embryos and could not germinate. More than 70% of the embryos in these seeds were molecularly identified as hybrids of both species, suggesting that HP tubes could enter the ovules and fertilize the egg cells. Moreover, CP could sire more offspring (≥70%) after the CP-HP (1:1) mixed pollination treatment, even when HP reached the stigma 0.5-1 h earlier than CP (≥50%). Following adequate CP vs. HP (1:1) pollination on carpels on two sides of the apocarpous gynoecium, both species produced > 70% conspecific seeds, indicating that the CP tubes could occupy ovules that should be occupied by HP via the extragynoecial compitum. Our results reveal that in Sagittaria, pollen deposition from co-existing congeneric heterospecies leads to interspecific seed discounting. However, the CP advantage mediated by the extragynoecial compitum is an effective strategy to mitigate the effects of interspecific pollen deposition. This study improves our understanding of how apocarpous angiosperms with an extragynoecial compitum can maintain species stability and mitigate the negative reproductive interference effect from sympatrically distributed related species.
Collapse
Affiliation(s)
- Cai-Hong Fei
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Sha-Sha Tang
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Shu-He Shang
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Dai
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Xin-Yi Wang
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Shuai Wang
- College of Life Science, Hengyang Normal University, Hengyang, China
| | - Wei-Qi Liu
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Xiao-Fan Wang
- College of Life Sciences, Wuhan University, Wuhan, China
| |
Collapse
|
3
|
Prior CJ, Busch JW. Selfing rate variation within species is unrelated to life-history traits or geographic range position. AMERICAN JOURNAL OF BOTANY 2021; 108:2294-2308. [PMID: 34632564 DOI: 10.1002/ajb2.1766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 08/25/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
PREMISE In plants, populations and species vary widely along the continuum from outcrossing to selfing. Life-history traits and ecological circumstances influence among-species variation in selfing rates, but their general role in explaining intraspecific variation is unknown. Using a database of plant species, we test whether life-history traits, geographic range position, or abundance predict selfing rate variation among populations. METHODS We identified species where selfing rates were estimated in at least three populations at known locations. Two key life-history traits (generation time and growth form) were used to predict within-species selfing rate variation. Populations sampled within a species' native range were assessed for proximity to the nearest edge and abundance. Finally, we conducted linear and segmented regressions to determine functional relationships between selfing rate and geographic range position within species. RESULTS Selfing rates for woody species varied less than for herbs, which is explained by the lower average selfing rate of woody species. Relationships between selfing and peripherality or abundance significantly varied among species in their direction and magnitude. However, there was no general pattern of increased selfing toward range edges. A power analysis shows that tests of this hypothesis require studying many (i.e., 40+) populations. CONCLUSIONS Intraspecific variation in plant mating systems is often substantial yet remains difficult to explain. Beyond sampling more populations, future tests of biogeographic hypotheses will benefit from phylogeographic information concerning specific range edges, the study of traits influencing mating system (e.g., herkogamy), and measures of abundance at local scales (e.g., population density).
Collapse
Affiliation(s)
- Carly J Prior
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| |
Collapse
|
4
|
Tripp EA, Dexter KG, Stone HB. Reproductive character displacement and potential underlying drivers in a species-rich and florally diverse lineage of tropical angiosperms ( Ruellia; Acanthaceae). Ecol Evol 2021; 11:4719-4730. [PMID: 33976842 PMCID: PMC8093712 DOI: 10.1002/ece3.7371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 12/05/2020] [Accepted: 12/10/2020] [Indexed: 11/08/2022] Open
Abstract
Reproductive character displacement is a pattern whereby sympatric lineages diverge more in reproductive character morphology than allopatric lineages. This pattern has been observed in many plant species, but comparably few have sought to disentangle underlying mechanisms. Here, in a diverse lineage of Neotropical plants (Ruellia; Acanthaceae), we present evidence of reproductive character displacement in a macroevolutionary framework (i.e., among species) and document mechanistic underpinnings. In a series of interspecific hand pollinations in a controlled glasshouse environment, we found that crosses between species that differed more in overall flower size, particularly in style length, were significantly less likely to produce viable seeds. Further, species pairs that failed to set seed were more likely to have sympatric distributions in nature. Competition for pollinators and reinforcement to avoid costly interspecific mating could both result in these patterns and are not mutually exclusive processes. Our results add to growing evidence that reproductive character displacement contributes to exceptional floral diversity of angiosperms.
Collapse
Affiliation(s)
- Erin A. Tripp
- Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderCOUSA
- Museum of Natural HistoryUniversity of ColoradoBoulderCOUSA
| | - Kyle G. Dexter
- School of GeoSciencesUniversity of EdinburghEdinburghUK
- Royal Botanic Garden EdinburghEdinburghUK
| | - Heather B. Stone
- Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderCOUSA
- Museum of Natural HistoryUniversity of ColoradoBoulderCOUSA
| |
Collapse
|
5
|
Toll K, LoPresti EF, Lowry DB. Inbreeding depression contributes to the maintenance of habitat segregation between closely related monkeyflower species. Evolution 2021; 75:832-846. [PMID: 33590496 DOI: 10.1111/evo.14192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 01/28/2021] [Accepted: 02/07/2021] [Indexed: 11/30/2022]
Abstract
Incompletely reproductively isolated species often segregate into different microhabitats, even when they are able to survive and reproduce in both habitats. Longer term evolutionary factors may contribute to this lack of cross-habitat persistence. When reproductive interference reduces immigrant fitness, assortative mating, including self-fertilization, increases immigrants' fitness in a single generation, but longer term, inbreeding depression may reduce the chance of population persistence. Two California monkeyflower species repeatedly segregate into drier and wetter areas in their zone of sympatry. To test whether inbreeding depression may contribute to the maintenance of this segregation pattern, we transplanted outbred and successively inbred Mimulus guttatus and Mimulus nudatus into their native habitats and heterospecific habitats. We measured germination, survival, and seed set and found that recurrent selfing reduced all aspects of fitness in both species, most strongly in foreign habitats. A simulation model, parameterized from the transplant experiment, found that inbreeding reduced fitness to such an extent that sequentially inbred populations of either species would be unable to persist in heterospecific-occupied habitats in the absence of continued gene flow. These results demonstrate that individual immigrants are unlikely to form persistent populations and thus, inbreeding depression contributes to the absence of fine-scale coexistence in this species pair.
Collapse
Affiliation(s)
- Katherine Toll
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824
| | - Eric F LoPresti
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824.,Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, Michigan, 48824
| |
Collapse
|
6
|
Orsucci M, Sicard A. Flower evolution in the presence of heterospecific gene flow and its contribution to lineage divergence. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:971-989. [PMID: 33537708 DOI: 10.1093/jxb/eraa549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
The success of species depends on their ability to exploit ecological resources in order to optimize their reproduction. However, species are not usually found within single-species ecosystems but in complex communities. Because of their genetic relatedness, closely related lineages tend to cluster within the same ecosystem, rely on the same resources, and be phenotypically similar. In sympatry, they will therefore compete for the same resources and, in the case of flowering plants, exchange their genes through heterospecific pollen transfer. These interactions, nevertheless, pose significant challenges to species co-existence because they can lead to resource limitation and reproductive interference. In such cases, divergent selective pressures on floral traits will favour genotypes that isolate or desynchronize the reproduction of sympatric lineages. The resulting displacement of reproductive characters will, in turn, lead to pre-mating isolation and promote intraspecific divergence, thus initiating or reinforcing the speciation process. In this review, we discuss the current theoretical and empirical knowledge on the influence of heterospecific pollen transfer on flower evolution, highlighting its potential to uncover the ecological and genomic constraints shaping the speciation process.
Collapse
Affiliation(s)
- Marion Orsucci
- Department of Plant Biology, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Adrien Sicard
- Department of Plant Biology, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| |
Collapse
|
7
|
Albertsen E, Opedal ØH, Bolstad GH, Pérez-Barrales R, Hansen TF, Pélabon C, Armbruster WS. Using ecological context to interpret spatiotemporal variation in natural selection. Evolution 2020; 75:294-309. [PMID: 33230820 DOI: 10.1111/evo.14136] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/20/2020] [Accepted: 10/03/2020] [Indexed: 12/14/2022]
Abstract
Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator-mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator-mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path-analytical approach, we assessed several functional components of selection, and linked variation in pollinator-mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross-pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross-pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.
Collapse
Affiliation(s)
- Elena Albertsen
- Norwegian Institute for Bioeconomy Research, Trondheim, 7031, Norway.,Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway.,Department of Biology, Lund University, Lund, SE-22362, Sweden
| | - Geir H Bolstad
- Norwegian Institute for Nature Research (NINA), Trondheim, 7485, Norway
| | - Rocío Pérez-Barrales
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, United Kingdom
| | - Thomas F Hansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, 0316, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, United Kingdom.,Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
| |
Collapse
|
8
|
Ostevik KL, Rifkin JL, Xia H, Rausher MD. Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation. Evol Lett 2020; 5:75-85. [PMID: 33552537 PMCID: PMC7857285 DOI: 10.1002/evl3.205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/04/2020] [Accepted: 10/19/2020] [Indexed: 01/25/2023] Open
Abstract
Hybridization between species can affect the strength of the reproductive barriers that separate those species. Two extensions of this effect are (1) the expectation that asymmetric hybridization or gene flow will have asymmetric effects on reproductive barrier strength and (2) the expectation that local hybridization will affect only local reproductive barrier strength and could therefore alter within‐species compatibility. We tested these hypotheses in a pair of morning glory species that exhibit asymmetric gene flow from highly selfing Ipomoea lacunosa into mixed‐mating Ipomoea cordatotriloba in regions where they co‐occur. Because of the direction of this gene flow, we predicted that reproductive barrier strength would be more strongly affected in I. cordatotriloba than I. lacunosa. We also predicted that changes to reproductive barriers in sympatric I. cordatotriloba populations would affect compatibility with allopatric populations of that species. We tested these predictions by measuring the strength of a reproductive barrier to seed set across the species’ ranges. Consistent with our first prediction, we found that sympatric and allopatric I. lacunosa produce the same number of seeds in crosses with I. cordatotriloba, whereas crosses between sympatric I. cordatotriloba and I. lacunosa are more successful than crosses between allopatric I. cordatotriloba and I. lacunosa. This difference in compatibility appears to reflect an asymmetric decrease in the strength of the barrier to seed set in sympatric I. cordatotriloba, which could be caused by I. lacunosa alleles that have introgressed into I. cordatotriloba. We further demonstrated that changes to sympatric I. cordatotriloba have decreased its ability to produce seeds with allopatric populations of the same species, in line with our second prediction. Thus, in a manner analogous to cascade reinforcement, we suggest that introgression associated with hybridization not only influences between‐species isolation but can also contribute to isolation within a species.
Collapse
Affiliation(s)
- Kate L Ostevik
- Department of Biology Duke University Durham North Carolina 27708
| | - Joanna L Rifkin
- Department of Ecology and Evolutionary Biology University of Toronto Toronto ON M5S 3B2 Canada
| | - Hanhan Xia
- College of Horticulture and Landscape Architecture Zhongkai University of Agriculture and Engineering Guangzhou 510225 China
| | - Mark D Rausher
- Department of Biology Duke University Durham North Carolina 27708
| |
Collapse
|
9
|
Hinojosa JC, Koubínová D, Dincă V, Hernández-Roldán J, Munguira ML, García-Barros E, Vila M, Alvarez N, Mutanen M, Vila R. Rapid colour shift by reproductive character displacement in Cupido butterflies. Mol Ecol 2020; 29:4942-4955. [PMID: 33051915 DOI: 10.1111/mec.15682] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 09/25/2020] [Accepted: 10/05/2020] [Indexed: 12/27/2022]
Abstract
Reproductive character displacement occurs when competition for successful breeding imposes a divergent selection on the interacting species, causing a divergence of reproductive traits. Here, we show that a disputed butterfly taxon is actually a case of male wing colour shift, apparently produced by reproductive character displacement. Using double digest restriction-site associated DNA sequencing and mitochondrial DNA sequencing we studied four butterfly taxa of the subgenus Cupido (Lepidoptera: Lycaenidae): Cupido minimus and the taxon carswelli, both characterized by brown males and females, plus C. lorquinii and C. osiris, both with blue males and brown females. Unexpectedly, taxa carswelli and C. lorquinii were close to indistinguishable based on our genomic and mitochondrial data, despite displaying strikingly different male coloration. In addition, we report and analysed a brown male within the C. lorquinii range, which demonstrates that the brown morph occurs at very low frequency in C. lorquinii. Such evidence strongly suggests that carswelli is conspecific with C. lorquinii and represents populations with a fixed male brown colour morph. Considering that these brown populations occur in sympatry with or very close to the blue C. osiris, and that the blue C. lorquinii populations never do, we propose that the taxon carswelli could have lost the blue colour due to reproductive character displacement with C. osiris. Since male colour is important for conspecific recognition during courtship, we hypothesize that the observed colour shift may eventually trigger incipient speciation between blue and brown populations. Male colour seems to be an evolutionarily labile character in the Polyommatinae, and the mechanism described here might be at work in the wide diversification of this subfamily of butterflies.
Collapse
Affiliation(s)
| | | | - Vlad Dincă
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Juan Hernández-Roldán
- Departamento de Biología - Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel L Munguira
- Departamento de Biología - Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Enrique García-Barros
- Departamento de Biología - Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Vila
- GIBE Research Group, Universidade da Coruña, A Coruña, Spain
| | | | - Marko Mutanen
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC-UPF), Barcelona, Spain
| |
Collapse
|
10
|
Benoit AD, Kalisz S. Predator Effects on Plant-Pollinator Interactions, Plant Reproduction, Mating Systems, and Evolution. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-012120-094926] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plants are the foundation of the food web and therefore interact directly and indirectly with myriad organisms at higher trophic levels. They directly provide nourishment to mutualistic and antagonistic primary consumers (e.g., pollinators and herbivores), which in turn are consumed by predators. These interactions produce cascading indirect effects on plants (either trait-mediated or density-mediated). We review how predators affect plant-pollinator interactions and thus how predators indirectly affect plant reproduction, fitness, mating systems, and trait evolution. Predators can influence pollinator abundance and foraging behavior. In many cases, predators cause pollinators to visit plants less frequently and for shorter durations. This decline in visitation can lead to pollen limitation and decreased seed set. However, alternative outcomes can result due to differences in predator, pollinator, and plant functional traits as well as due to altered interaction networks with plant enemies. Furthermore, predators may indirectly affect the evolution of plant traits and mating systems.
Collapse
Affiliation(s)
- Amanda D. Benoit
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996, USA;,
| | - Susan Kalisz
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996, USA;,
| |
Collapse
|
11
|
Jiménez-López FJ, Ortiz PL, Talavera M, Pannell JR, Arista M. The role of lateral and vertical herkogamy in the divergence of the blue- and red-flowered lineages of Lysimachia arvensis. ANNALS OF BOTANY 2020; 125:1127-1135. [PMID: 32185392 PMCID: PMC7262470 DOI: 10.1093/aob/mcaa047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 03/15/2020] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Herkogamy, or anther-stigma separation, is known to reduce self-pollen deposition, but little is known about the relative efficacy of different modes or conformations of herkogamy. We assessed the effectiveness of vertical versus lateral herkogamy in preventing or promoting self-pollen deposition in the annual herb Lysimachia arvensis, a plant with lineages that differ in flower colour, and in which flowers first display lateral and then vertical herkogamy. Because mating between the two lineages compromises fitness through the production of low-quality hybrid offspring, we tested the prediction that individuals sampled from sites occupied by both lineages should have flowers that promote autonomous self-pollen deposition and self-fertilization as a result of selection to reduce deleterious reproductive interference. METHODS We characterized variation in herkogamy within and among 25 pure and mixed populations of L. arvensis in its European range and assessed the effectiveness of lateral versus vertical herkogamy in avoiding self-pollen deposition. RESULTS Lateral herkogamy was more effective than vertical herkogamy in limiting self-pollen deposition. In the case of vertical herkogamy, only approach herkogamy was effective. Lineages showed consistent differences in herkogamy traits. In general, angles were smaller for blue than red flowers in most populations, and blue flowers showed approach herkogamy, while red flowers showed predominantly reverse herkogamy. In sympatry, the red lineage showed a reduction of both herkogamy traits while for the blue lineage only lateral herkogamy was reduced. CONCLUSIONS Our results demonstrate that pollen deposition is affected not only by the degree but also the spatial conformation of herkogamy. They also highlight reduced herkogamy as a potential mechanism for promoting reproductive assurance under pollen limitation, as well as for avoiding reproductive interference between genetically divergent lineages.
Collapse
Affiliation(s)
- F J Jiménez-López
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - P L Ortiz
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - M Talavera
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - J R Pannell
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - M Arista
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| |
Collapse
|
12
|
Christie K, Strauss SY. Frequency-dependent fitness and reproductive dynamics contribute to habitat segregation in sympatric jewelflowers. Proc Biol Sci 2020; 287:20200559. [PMID: 32396796 DOI: 10.1098/rspb.2020.0559] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Coexistence results from a complex suite of past and contemporary processes including biogeographic history, adaptation, ecological interactions and reproductive dynamics. Here we explore drivers of local micro-parapatry in which two closely related and reproductively isolated Streptanthus species (jewelflower, Brassicaceae) inhabit continuous or adjacent habitat patches and occur within seed dispersal range, yet rarely overlap in fine-scale distribution. We find some evidence for abiotic niche partitioning and local adaptation, however differential survival across habitats cannot fully explain the scarcity of coexistence. Competition may also reduce the fitness of individuals migrating into occupied habitats, yet its effects are insufficient to drive competitive exclusion. Experimental migrants suffered reduced seed production and seed viability at sites occupied by heterospecifics, and we infer that heterospecific pollen transfer by shared pollinators contributes to wasted gametes when the two congeners come into contact. A minority disadvantage may reduce effective colonization of patches already occupied by heterospecifics, even when habitat patches are environmentally suitable. Differential adaptation and resource competition have often been evoked as primary drivers of habitat segregation in plants, yet negative reproductive interactions-including reproductive interference and decreased fecundity among low-frequency migrants-may also contribute to non-overlapping distributions of related species along local tension zones.
Collapse
Affiliation(s)
- Kyle Christie
- Department of Evolution and Ecology, and Center for Population Biology, University of California Davis, One Shields Avenue, Davis CA 95616-5270, USA
| | - Sharon Y Strauss
- Department of Evolution and Ecology, and Center for Population Biology, University of California Davis, One Shields Avenue, Davis CA 95616-5270, USA
| |
Collapse
|
13
|
Newman E, Anderson B. Character displacement drives floral variation in Pelargonium (Geraniaceae) communities. Evolution 2020; 74:283-296. [PMID: 31883274 DOI: 10.1111/evo.13908] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/01/2019] [Accepted: 11/26/2019] [Indexed: 11/30/2022]
Abstract
Interactions between plant community members are an underexplored driver of angiosperm floral variation. We investigate character displacement as a potential contributor to floral variation in Pelargonium communities. Pelargoniums all place pollen on the ventral sides of their pollinators, potentially leading to interspecific pollen transfer (IPT) in sympatry. We show that the positions of pollen placement and receipt are determined by anther and style exsertion lengths. Using field experiments, we demonstrate that heterospecific species experience higher IPT if they have similar style lengths than when they have greater style length differences. Using crosses, we show that IPT has negative consequences on seed set. In combination, these results suggest that character displacement in style length is likely to reduce IPT and increase female fitness in sympatry. Patterns of style length variation across 29 different Pelargonium communities suggest that character displacement has occurred in multiple communities. Furthermore, analyses using a wide-ranging species pair show that style lengths are more different between sympatric populations than they are between allopatric populations. In addition to pollinators as agents of floral divergence, this study suggests that variation in Pelargonium community structure has driven style length variation through character displacement.
Collapse
Affiliation(s)
- Ethan Newman
- Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, 7602, South Africa
| | - Bruce Anderson
- Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, 7602, South Africa
| |
Collapse
|
14
|
Moreira-Hernández JI, Muchhala N. Importance of Pollinator-Mediated Interspecific Pollen Transfer for Angiosperm Evolution. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2019. [DOI: 10.1146/annurev-ecolsys-110218-024804] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding how pollen moves between species is critical to understanding speciation, diversification, and evolution of flowering plants. For co-flowering species that share pollinators, competition through interspecific pollen transfer (IPT) can profoundly impact floral evolution, decreasing female fitness via heterospecific pollen deposition on stigmas and male fitness via pollen misplacement during visits to heterospecific flowers. The pollination literature demonstrates that such reproductive interference frequently selects for reproductive character displacement in floral traits linked to pollinator attraction, pollen placement, and mating systems and has also revealed that IPT between given pairs of species is typically asymmetric. More recent work is starting to elucidate its importance to the speciation process, clarifying the link between IPT and current and historical patterns of hybridization, the evolution of phenotypic novelty through adaptive introgression, and the rise of reproductive isolation. Our review aims to stimulate further research on IPT as a ubiquitous mechanism that plays a central role in angiosperm diversification.
Collapse
Affiliation(s)
- Juan Isaac Moreira-Hernández
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
| | - Nathan Muchhala
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
| |
Collapse
|
15
|
Pickup M, Brandvain Y, Fraïsse C, Yakimowski S, Barton NH, Dixit T, Lexer C, Cereghetti E, Field DL. Mating system variation in hybrid zones: facilitation, barriers and asymmetries to gene flow. THE NEW PHYTOLOGIST 2019; 224:1035-1047. [PMID: 31505037 PMCID: PMC6856794 DOI: 10.1111/nph.16180] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/19/2019] [Indexed: 05/11/2023]
Abstract
Plant mating systems play a key role in structuring genetic variation both within and between species. In hybrid zones, the outcomes and dynamics of hybridization are usually interpreted as the balance between gene flow and selection against hybrids. Yet, mating systems can introduce selective forces that alter these expectations; with diverse outcomes for the level and direction of gene flow depending on variation in outcrossing and whether the mating systems of the species pair are the same or divergent. We present a survey of hybridization in 133 species pairs from 41 plant families and examine how patterns of hybridization vary with mating system. We examine if hybrid zone mode, level of gene flow, asymmetries in gene flow and the frequency of reproductive isolating barriers vary in relation to mating system/s of the species pair. We combine these results with a simulation model and examples from the literature to address two general themes: (1) the two-way interaction between introgression and the evolution of reproductive systems, and (2) how mating system can facilitate or restrict interspecific gene flow. We conclude that examining mating system with hybridization provides unique opportunities to understand divergence and the processes underlying reproductive isolation.
Collapse
Affiliation(s)
- Melinda Pickup
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - Yaniv Brandvain
- Department of Plant and Microbial BiologyUniversity of Minnesota1500 Gortner AveSt Paul, MinneapolisMN55108USA
| | - Christelle Fraïsse
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - Sarah Yakimowski
- Department of BiologyQueen's University116 Barrie StKingstonONK7L 3N6Canada
| | - Nicholas H. Barton
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - Tanmay Dixit
- Department of ZoologyUniversity of CambridgeDowning StreetCambridgeCB2 3EJUK
| | - Christian Lexer
- Department of Botany and Biodiversity ResearchFaculty of Life SciencesUniversity of ViennaA‐1030ViennaAustria
| | - Eva Cereghetti
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - David L. Field
- Department of Botany and Biodiversity ResearchFaculty of Life SciencesUniversity of ViennaA‐1030ViennaAustria
- School of ScienceEdith Cowan University270 Joondalup DriveJoondalupWestern Australia6027Australia
| |
Collapse
|
16
|
Global geographic patterns of heterospecific pollen receipt help uncover potential ecological and evolutionary impacts across plant communities worldwide. Sci Rep 2019; 9:8086. [PMID: 31147606 PMCID: PMC6542810 DOI: 10.1038/s41598-019-44626-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 05/21/2019] [Indexed: 11/09/2022] Open
Abstract
Species interactions are known to be key in driving patterns of biodiversity across the globe. Plant-plant interactions through heterospecific pollen (HP) transfer by their shared pollinators is common and has consequences for plant reproductive success and floral evolution, and thus has the potential to influence global patterns of biodiversity and plant community assembly. The literature on HP transfer is growing and it is therefore timely to review patterns and causes of among-species variation in HP receipt at a global scale, thus uncovering its potential contribution to global patterns of biodiversity. Here we analyzed published data on 245 species distributed across five continents to evaluate latitudinal and altitudinal patterns of HP receipt. We further analyzed the role of floral symmetry and evolutionary history in mediating patterns of HP receipt. Latitude and elevation affected the likelihood and intensity of HP receipt indicating that HP transfer increases in species-rich communities and in areas with high abundance of vertebrate pollinators. Floral symmetry and evolutionary history determined HP load size across plant communities worldwide. Overall, our results suggest that HP receipt may have the potential to contribute to global geographic patterns of plant diversity by imposing strong selective pressures in species-rich areas across the globe.
Collapse
|
17
|
Katsuhara KR, Ushimaru A. Prior selfing can mitigate the negative effects of mutual reproductive interference between coexisting congeners. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13344] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Koki R. Katsuhara
- Graduate School of Human Development and Environment Kobe University Kobe Japan
| | - Atushi Ushimaru
- Graduate School of Human Development and Environment Kobe University Kobe Japan
| |
Collapse
|
18
|
Aguilar-Rodríguez PA, Tschapka M, García-Franco JG, Krömer T, MacSwiney G MC. Bromeliads going batty: pollinator partitioning among sympatric chiropterophilous Bromeliaceae. AOB PLANTS 2019; 11:plz014. [PMID: 31186827 PMCID: PMC6537948 DOI: 10.1093/aobpla/plz014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/08/2019] [Indexed: 06/09/2023]
Abstract
Pollinators can be a limited resource and natural selection should favour differences in phenotypic characteristics to reduce competition among plants. Bats are important pollinators of many Neotropical plants, including the Bromeliaceae; however, the pre-pollination mechanisms for isolation among sympatric bat-pollinated bromeliads are unknown. Here, we studied the mechanisms for reproductive segregation between Pitcairnia recurvata, Pseudalcantarea viridiflora, Werauhia noctiflorens and W. nutans. The study was conducted at Los Tuxtlas Biosphere Reserve, in Veracruz, Mexico We carried out ex situ and in situ manual pollination treatments to determine the breeding system by assessing fruiting and seedling success and sampled bat visitors using mist-nets and infrared cameras. We determined the nocturnal nectar production pattern, estimating the energetic content of this reward. All four bromeliads are self-compatible, but only P. recurvata appears to require pollinators, because the physical separation between anthers and stigma prevents self-pollination, it is xenogamous and presents a strictly nocturnal anthesis. The bats Anoura geoffroyi, Glossophaga soricina and Hylonycteris underwoodi are probable pollinators of three of the studied bromeliads. We did not record any animal visiting the fourth species. The flowering season of each species is staggered throughout the year, with minimal overlap, and the floral morphology segregates the locations on the body of the bat where the pollen is deposited. The most abundant nectar per flower is provided by P. viridiflora, but P. recurvata offers the best reward per hectare, considering the density of flowering plants. Staggered flowering, different pollen deposition sites on the body of the pollinator and differences in the reward offered may have evolved to reduce the competitive costs of sharing pollinators while providing a constant supply of food to maintain a stable nectarivorous bat community.
Collapse
Affiliation(s)
- Pedro Adrián Aguilar-Rodríguez
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
- Department of Zoology, Tel Aviv University, Tel Aviv, Israel
| | - Marco Tschapka
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert Einstein Allee 11, D Ulm, Germany
- Smithsonian Tropical Research Institute, Balboa Ancón, Apartado, Panamá, Republica de Panamáa
| | - José G García-Franco
- Red de Ecología Funcional, Instituto de Ecología, A.C., Carretera Antigua a Coatepec No. 351, El Haya, C.P. Xalapa, Veracruz, México
| | - Thorsten Krömer
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
| | - M Cristina MacSwiney G
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
| |
Collapse
|
19
|
Kay KM, Zepeda AM, Raguso RA. Experimental sympatry reveals geographic variation in floral isolation by hawkmoths. ANNALS OF BOTANY 2019; 123:405-413. [PMID: 30032166 PMCID: PMC6344223 DOI: 10.1093/aob/mcy143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND AND AIMS Under a widely accepted model of pollinator-driven speciation, geographic variation in pollinator assemblage drives floral divergence and automatically causes reproductive isolation. Yet it is unclear whether divergent floral adaptation initially confers strong reproductive isolation, or whether that comes at later stages of speciation and requires other forms of reproductive isolation. This study uses a pair of recently diverged, interfertile and parapatric species in the genus Clarkia to determine whether adaptation to hawkmoths, a novel pollinator functional group, would automatically confer floral isolation upon sympatric contact. METHODS First, genetically based differences in floral traits between C. breweri and C. concinna that would be maintained upon migration are quantified. Then scenarios of experimental sympatry are constructed in which arrays of flowers are exposed to the novel pollinator, the hawkmoth Hyles lineata, and pollinator preference and heterospecific pollen transfer are assessed. Source populations from across the ranges of each species are used to understand how geographic variation in floral traits within species may affect floral isolation. KEY RESULTS Although H. lineata has never been observed visiting C. concinna in the wild, it regularly moves between species in experimental floral arrays. Hawkmoth preference and heterospecific pollen transfer vary both among moths and among geographic source locations of C. concinna. The strength of floral isolation in this system is related to variation in flower size, especially hypanthium tube width, and nectar reward among C. concinna forms. CONCLUSIONS Although C. breweri has adopted a novel hawkmoth pollination system, both ethological and mechanical floral isolation by hawkmoths are incomplete and vary according to the specific phenotype of the C. concinna source population. The results suggest that strong floral isolation is not automatically conferred by a pollinator shift and may require additional evolution of deterrent floral traits and habitat isolation that reduces the immediate spatial co-occurrence of young species.
Collapse
Affiliation(s)
- Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Aubrey M Zepeda
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| |
Collapse
|
20
|
Kemp JE, Bergh NG, Soares M, Ellis AG. Dominant pollinators drive non-random community assembly and shared flower colour patterns in daisy communities. ANNALS OF BOTANY 2019; 123:277-288. [PMID: 29992277 PMCID: PMC6344215 DOI: 10.1093/aob/mcy126] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/13/2018] [Indexed: 05/20/2023]
Abstract
Background and Aims As most plants rely on pollination for persistence in communities, pollination interactions should be important determinants of plant community assembly. Here, trait and phylogenetic null modelling approaches were combined with pollinator interaction networks to elucidate the processes structuring flower colour assembly patterns in Asteraceae communities in Namaqualand, South Africa. Methods Plant species were assigned to flower colour pattern categories (CPCs) that incorporate the complexity of the bulls-eye colour pattern, using pollinator vision models. Null models were used to assess whether daisy communities exhibit clustering (driven by filtering, facilitation or convergence) or overdispersion (driven by competitive exclusion or character displacement) of CPCs. Next, flower visitor networks were constructed for communities with non-random CPC assembly to confirm the functional role of pollinators in determining floral trait assembly. Key Results Plant species are unevenly distributed across CPCs, the majority of which are not phylogenetically conserved, suggesting that certain CPCs have a selective advantage. Clustering of CPCs in communities is more frequent than overdispersion, and this does not reflect non-random phylogenetic assembly. In most communities at least one CPC is overrepresented relative to null assemblages. Interaction networks show that each community has a single dominant pollinator that strongly interacts with the overrepresented CPC, suggesting a role for pollinator preferences in driving clustered assembly of CPCs within daisy communities. Conclusion This novel approach, which demonstrates non-random assembly of complex flower colour patterns and corroborates their functional association with particular pollinators, provides strong evidence that pollinators influence plant community assembly. Results suggest that in some community contexts the benefits of pollinator sharing outweigh the costs of heterospecific pollen transfer, generating clustered assembly. They also challenge the perception of generalized pollination in daisies, suggesting instead that complex daisy colour patterns represent a pollination syndrome trait linked to specific fly pollinators.
Collapse
Affiliation(s)
- Jurene E Kemp
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Nicola G Bergh
- The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Newlands, Cape Town, South Africa
- The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Muri Soares
- The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Allan G Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| |
Collapse
|
21
|
Roda F, Hopkins R. Correlated evolution of self and interspecific incompatibility across the range of a Texas wildflower. THE NEW PHYTOLOGIST 2019; 221:553-564. [PMID: 29992588 DOI: 10.1111/nph.15340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/10/2018] [Indexed: 06/08/2023]
Abstract
Selection to prevent interspecific mating can cause an increase or a decrease in self-pollination in sympatric populations. Characterizing the geographical variation in self and interspecific incompatibilities within a species can reveal if and how the evolution of self and interspecific mate choice are linked. We used controlled pollinations to characterize the variation in self and interspecific incompatibility across 29 populations of Phlox drummondii. We evaluated seed set from these pollinations and described the developmental timing of variation in pollen-pistil compatibility. There is extensive quantitative variation in self-incompatibility and interspecific-incompatibility with its close congener P. cuspidata. Phlox drummondii populations that co-occur and hybridize with P. cuspidata have significantly higher interspecific incompatibility and self-incompatibility than geographically isolated P. drummondii populations. The strength of self and interspecific incompatibility is significantly correlated among individuals and the strength of both incompatibilities is explained by the success of pollen adhesion to the stigma. The correlated strength of self and interspecific incompatibility across the range of P. drummondii and the concurrent developmental timing of the pollen-pistil interaction, suggests these incompatibilities have an overlapping molecular mechanism. The geographical distribution of variation in incompatibilities indicates that this mechanistic link between incompatibilities may affect the evolution of mate choice in plants.
Collapse
Affiliation(s)
- Federico Roda
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
| |
Collapse
|
22
|
Hu XS, Zhang XX, Zhou W, Hu Y, Wang X, Chen XY. Mating system shifts a species' range. Evolution 2018; 73:158-174. [PMID: 30592527 DOI: 10.1111/evo.13663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 12/05/2018] [Indexed: 01/20/2023]
Abstract
Understanding the ecological and evolutionary mechanisms that shape a species' range is an important goal in evolutionary biology. Evidence indicates that mating system is an effective predictor of the global range of native species or naturalized alien plants, but the mechanisms underlying this predictability are not elaborated. Here, we develop a theoretical model to account for the ranges of plants under different mating systems based on migration-selection processes (an idea proposed by Haldane). The model includes alternation of gametophyte and sporophyte generations in one life cycle and the dispersal of haploid pollen and diploid seeds as vectors for gene flow. We show that the interaction between selfing rates and gametophytic selection determines the role of mating system in shaping a species' range. Selfing restricts the species' range under gametophytic selection in nonrandom mating systems, but expands the species' range under the absence of gametophytic selection in any mating system. Gametophytic selection slightly restricts the species' range in random mating. Both logarithmic and logistic models of population demography yield similar conclusions in the case of fixed or evolving genetic variance. The theory also helps to explain a broader relationship between mating system and range size following biological invasion or plant naturalization.
Collapse
Affiliation(s)
- Xin-Sheng Hu
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| | - Xin-Xin Zhang
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| | - Wei Zhou
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| | - Ying Hu
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| | - Xi Wang
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| | - Xiao-Yang Chen
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangdong, 510642, China.,College of Forestry and Landscape Architecture, South China Agricultural University, Guangdong, 510642, China
| |
Collapse
|
23
|
Eisen KE, Geber MA. Ecological sorting and character displacement contribute to the structure of communities of Clarkia species. J Evol Biol 2018; 31:1440-1458. [PMID: 30099807 DOI: 10.1111/jeb.13365] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 07/10/2018] [Accepted: 08/06/2018] [Indexed: 01/27/2023]
Abstract
Despite long-standing interest in the evolutionary ecology of plants that share pollinators, few studies have explored how these interactions may affect communities during both community assembly (ecological sorting) and through ongoing, in situ evolution (character displacement), and how the effects of these interactions may change with community context. To determine if communities display patterns consistent with ecological sorting, we assessed the frequency of co-occurrence of four species of Clarkia in the southern Sierra foothills (Kern County, CA, USA). To investigate potential character displacement, we measured pollination-related traits on plants grown in a greenhouse common garden from seed collected in communities with one, two or four Clarkia species. Among the four species of Clarkia in this region, the two species that are often found in multi-species communities also co-occur with one another more frequently than expected under a null model. This pattern is consistent with ecological sorting, although further investigation is needed to determine the role of pollinators in shaping community assembly. Patterns of trait variation in a common garden suggest that these two species have diverged in floral traits and converged in flowering time where they co-occur, which is consistent with character displacement. Trait variation across community types also suggests that the process and outcome of character displacement may vary with community context. Because community context appears to affect both the direction and magnitude of character displacement, change in more species-rich communities may not be predictable from patterns of change in simpler communities.
Collapse
Affiliation(s)
- Katherine E Eisen
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Monica A Geber
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| |
Collapse
|
24
|
Whitton J, Sears CJ, Maddison WP. Co-occurrence of related asexual, but not sexual, lineages suggests that reproductive interference limits coexistence. Proc Biol Sci 2018; 284:rspb.2017.1579. [PMID: 29212720 DOI: 10.1098/rspb.2017.1579] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/03/2017] [Indexed: 02/02/2023] Open
Abstract
We used randomizations to analyse patterns of co-occurrence of sexual and apomictic (asexual) members of the North American Crepis agamic complex (Asteraceae). We expect strong asymmetry in reproductive interactions in Crepis: apomicts produce clonal seeds with no need for pollination and are not subject to reproductive interference from co-occurring relatives. However, because they still produce some viable pollen, apomicts can reduce reproductive success of nearby sexual relatives, potentially leading to eventual local exclusion of sexuals. Consistent with this, randomizations reveal that sexuals are over-represented in isolated sites, while apomicts freely co-occur. Incorporation of taxonomic and phylogenetic evidence indicates that this pattern is not driven by local origins of asexuals. Our evidence that patterns of local co-occurrence are structured by reproductive interference suggests an underappreciated role for these interactions in community assembly, and highlights the need for explicit tests of the relative contributions of ecological and reproductive interactions in generating patterns of limiting similarity.
Collapse
Affiliation(s)
- Jeannette Whitton
- Department of Botany and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher J Sears
- Department of Botany and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Wayne P Maddison
- Department of Botany and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada.,Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
25
|
Randle AM, Spigler RB, Kalisz S. Shifts to earlier selfing in sympatry may reduce costs of pollinator sharing. Evolution 2018; 72:1587-1599. [PMID: 29917223 DOI: 10.1111/evo.13522] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 01/02/2023]
Abstract
Coexisting plant congeners often experience strong competition for resources. Competition for pollinators can result in direct fitness costs via reduced seed set or indirect costs via heterospecific pollen transfer (HPT), causing subsequent gamete loss and unfit hybrid offspring production. Autonomous selfing may alleviate these costs, but to preempt HPT, selfing should occur early, before opportunities for HPT occur (i.e., "preemptive selfing hypothesis"). We evaluated conditions for this hypothesis in Collinsia sister species, C. linearis and C. rattanii. In field studies, we found virtually identical flowering times and pollinator sharing between congeners in sympatric populations. Compared to allopatric populations, sympatric C. linearis populations enjoyed higher pollinator visitation rates, whereas visitation to C. rattanii did not differ in sympatry. Importantly, the risk of HPT to each species in sympatry was strongly asymmetrical; interspecies visits comprised 40% of all flower-to-flower visits involving C. rattanii compared to just 4% involving C. linearis. Additionally, our greenhouse experiment demonstrated a strong cost of hybridization when C. rattanii was the pollen donor. Together, these results suggest that C. rattanii pays the greatest cost of pollinator sharing. Matching predictions of the preemptive selfing hypothesis, C. rattanii exhibit significantly earlier selfing in sympatric relative to allopatric populations.
Collapse
Affiliation(s)
- April M Randle
- Department of Environmental Science, University of San Francisco, San Francisco, California, 94117
| | - Rachel B Spigler
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Susan Kalisz
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Knoxville, Tennessee, 37919
- Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, 15213
| |
Collapse
|
26
|
Whitehead MR, Lanfear R, Mitchell RJ, Karron JD. Plant Mating Systems Often Vary Widely Among Populations. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00038] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
27
|
Garner AG, Goulet BE, Farnitano MC, Molina-Henao YF, Hopkins R. Genomic Signatures of Reinforcement. Genes (Basel) 2018; 9:E191. [PMID: 29614048 PMCID: PMC5924533 DOI: 10.3390/genes9040191] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 12/21/2022] Open
Abstract
Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement's characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved.
Collapse
Affiliation(s)
- Austin G Garner
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 021382, USA.
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA.
| | - Benjamin E Goulet
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 021382, USA.
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA.
| | - Matthew C Farnitano
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 021382, USA.
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA.
| | - Y Franchesco Molina-Henao
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 021382, USA.
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA.
- Department of Biology, Universidad del Valle, Cali 760032, Colombia.
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 021382, USA.
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA.
| |
Collapse
|
28
|
Jordan CY, Lohse K, Turner F, Thomson M, Gharbi K, Ennos RA. Maintaining their genetic distance: Little evidence for introgression between widely hybridizing species of Geum with contrasting mating systems. Mol Ecol 2018; 27:1214-1228. [PMID: 29134729 PMCID: PMC5900869 DOI: 10.1111/mec.14426] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 11/02/2017] [Accepted: 11/02/2017] [Indexed: 01/02/2023]
Abstract
Within the plant kingdom, many genera contain sister lineages with contrasting outcrossing and inbreeding mating systems that are known to hybridize. The evolutionary fate of these sister lineages is likely to be influenced by the extent to which they exchange genes. We measured gene flow between outcrossing Geum rivale and selfing Geum urbanum, sister species that hybridize in contemporary populations. We generated and used a draft genome of G. urbanum to develop dd-RAD data scorable in both species. Coalescent analysis of RAD data from allopatric populations indicated that the species diverged 2-3 Mya, and that historical gene flow between them was extremely low (1 migrant every 25 generations). Comparison of genetic divergence between species in sympatry and allopatry, together with an analysis of allele frequencies in potential parental and hybrid populations, provided no evidence of contemporary introgression in sympatric populations. Cluster- and species-specific marker analyses revealed that, apart from four early-generation hybrids, individuals in sympatric populations fell into two genetically distinct groups that corresponded exactly to their morphological species classification with maximum individual admixture estimates of only 1-3%. However, we did observe joint segregation of four putatively introgressed SNPs across two scaffolds in the G. urbanum population that was associated with significant morphological variation, interpreted as tentative evidence for rare, recent interspecific gene flow. Overall, our results indicate that despite the presence of hybrids in contemporary populations, genetic exchange between G. rivale and G. urbanum has been extremely limited throughout their evolutionary history.
Collapse
Affiliation(s)
- Crispin Y. Jordan
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
| | - Konrad Lohse
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
| | | | | | - Karim Gharbi
- Ashworth LaboratoriesEdinburgh GenomicsEdinburghUK
| | - Richard A. Ennos
- Ashworth LaboratoriesInstitute of Evolutionary BiologyUniversity of EdinburghEdinburghUK
| |
Collapse
|
29
|
Neri J, Wendt T, Palma-Silva C. Natural hybridization and genetic and morphological variation between two epiphytic bromeliads. AOB PLANTS 2018; 10:plx061. [PMID: 29308124 PMCID: PMC5751037 DOI: 10.1093/aobpla/plx061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 11/22/2017] [Indexed: 05/18/2023]
Abstract
Reproductive isolation is of fundamental importance for maintaining species boundaries in sympatry. Here, we examine the genetic and morphological differences between two closely related bromeliad species: Vriesea simplex and Vriesea scalaris. Furthermore, we examined the occurrence of natural hybridization and discuss the action of reproductive isolation barriers. Nuclear genomic admixture suggests hybridization in sympatric populations, although interspecific gene flow is low among species in all sympatric zones (Nem < 0.5). Thus, morphological and genetic divergence (10.99 %) between species can be maintained despite ongoing natural hybridization. Cross-evaluation of our genetic and morphological data suggests that species integrity is maintained by the simultaneous action of multiple barriers, such as divergent reproductive systems among species, differences in floral traits and low hybrid seed viability.
Collapse
Affiliation(s)
- Jordana Neri
- Programa de Pós Graduação em Botânica, Departamento de Botânica, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, São Cristóvão, Rio de Janeiro, RJ, Brazil
| | - Tânia Wendt
- Departamento de Botânica, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Clarisse Palma-Silva
- Programa de Pós Graduação em Ecologia, Departamento de Ecologia – Universidade Estadual Paulista Julio Mesquita Filho, Rio Claro, SP, Brazil
| |
Collapse
|
30
|
Koski MH, Kuo L, Niedermaier KM, Galloway LF. Timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations. AMERICAN JOURNAL OF BOTANY 2018; 105:241-248. [PMID: 29578289 DOI: 10.1002/ajb2.1025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/29/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY The evolution of multiple floral traits often underlies the transition from outcrossing to selfing. Such traits can influence the ability to self, and the timing at which selfing occurs, which in turn affects the costs of selfing. Species that display variation in autonomous selfing provide an opportunity to dissect the phenotypic changes that contribute to variability in the mating system. METHODS In a common garden, we measured dichogamy and herkogamy in 24 populations of the protandrous mixed-mating herb Campanula americana, and related these to autonomous fruit set (autonomy). We then measured the timing of self-pollen deposition and fruit production in populations with high and low autonomy, and determined whether pollen germinability across floral development contributes to variation in autonomy. KEY RESULTS Populations that transitioned more rapidly to female phase displayed elevated autonomous selfing, but herkogamy was unassociated with autonomous selfing. Selfing occurred more rapidly in highly autonomous populations because of greater self-pollen deposition early in female phase. Pollen germinability in low-autonomy populations remained constant across floral development, but in high-autonomy populations it increased after floral anthesis and was highest near the onset of female phase. CONCLUSIONS Reduced dichogamy, elevated self-pollen deposition, and higher pollen germination late in male phase contribute to both earlier selfing and greater selfing. These traits vary among populations, likely reflecting past selection on the mating system. While delayed selfing bears fewer fitness costs, the evolution of earlier selfing may be favored if self-pollen availability decreases over floral development.
Collapse
Affiliation(s)
- Matthew H Koski
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
| | - Liao Kuo
- Wuhan Botanical Garden, Chinese Academy of Science, Moshan Wuchang, Wuhan, P.R. China, 430074
| | - Kerstin M Niedermaier
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
| | - Laura F Galloway
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
| |
Collapse
|
31
|
Charlebois JA, Sargent RD. No consistent pollinator-mediated impacts of alien plants on natives. Ecol Lett 2017; 20:1479-1490. [PMID: 28901037 DOI: 10.1111/ele.12831] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/08/2017] [Accepted: 07/31/2017] [Indexed: 11/28/2022]
Abstract
The introduction of an alien plant is widely assumed to have negative consequences for the pollinator-mediated fitness of nearby natives. Indeed, a number of studies, including a highly cited meta-analysis, have concluded that the trend for such interactions is competitive. Here we provide evidence that publication bias and study design have obscured our ability to assess the pollinator-mediated impacts of alien plants. In a meta-analysis of 76 studies, we demonstrate that alien/native status does not predict the outcome of pollinator-mediated interactions among plants. Moreover, we found no evidence that similarity in floral traits or phylogenetic distance between species pairs influences the outcome of pollinator-mediated interactions. Instead, we report that aspects of study design, such as distance between the control and nearest neighbour, and/or the arrangement of study plants better predict the impact of a neighbour than does alien/native status. Our study sheds new light on the role that publication bias and experimental design play in the evaluation of key patterns in ecology. We conclude that, due to the absence of clear, generalisable pollinator-mediated impacts of alien species, management schemes should base decisions on community-wide assessments of the impacts of individual alien plant species, and not solely on alien/native status itself.
Collapse
Affiliation(s)
| | - Risa D Sargent
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| |
Collapse
|
32
|
Geographic variation in floral traits and the capacity of autonomous selfing across allopatric and sympatric populations of two closely related Centaurium species. Sci Rep 2017; 7:46410. [PMID: 28429781 PMCID: PMC5399455 DOI: 10.1038/srep46410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/07/2017] [Indexed: 02/02/2023] Open
Abstract
Floral traits and the relative contribution of autonomous selfing to total seed set varies geographically and is often driven by the availability and abundance of suitable pollinators and/or the presence of co-flowering relatives. In the latter case, competition for pollinator services and costs of hybridization can select for floral traits that reduce interspecific gene flow and contribute to prezygotic isolation, potentially leading to geographic variation in floral divergence between allopatric and sympatric populations. In this study, we investigated variation in floral traits and its implications on the capacity of autonomous selfing in both allopatric and sympatric populations of two closely related Centaurium species(Gentianaceae) across two distinct geographic regions(UK and mainland Europe). Although the magnitude and direction of floral differentiation varied between regions, sympatric populations were always significantly more divergent in floral traits and the capacity to self autonomously than allopatric populations. These results indicate that mating systems can vary substantially within a species and that the joint occurrence of plant species can have a major impact on floral morphology and capacity of autonomous selfing, most likely as a way to reduce the probability of interspecific interference.
Collapse
|
33
|
Moeller DA, Briscoe Runquist RD, Moe AM, Geber MA, Goodwillie C, Cheptou PO, Eckert CG, Elle E, Johnston MO, Kalisz S, Ree RH, Sargent RD, Vallejo-Marin M, Winn AA. Global biogeography of mating system variation in seed plants. Ecol Lett 2017; 20:375-384. [PMID: 28116770 DOI: 10.1111/ele.12738] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/16/2016] [Accepted: 12/21/2016] [Indexed: 11/29/2022]
Abstract
Latitudinal gradients in biotic interactions have been suggested as causes of global patterns of biodiversity and phenotypic variation. Plant biologists have long speculated that outcrossing mating systems are more common at low than high latitudes owing to a greater predictability of plant-pollinator interactions in the tropics; however, these ideas have not previously been tested. Here, we present the first global biogeographic analysis of plant mating systems based on 624 published studies from 492 taxa. We found a weak decline in outcrossing rate towards higher latitudes and among some biomes, but no biogeographic patterns in the frequency of self-incompatibility. Incorporating life history and growth form into biogeographic analyses reduced or eliminated the importance of latitude and biome in predicting outcrossing or self-incompatibility. Our results suggest that biogeographic patterns in mating system are more likely a reflection of the frequency of life forms across latitudes rather than the strength of plant-pollinator interactions.
Collapse
Affiliation(s)
- David A Moeller
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Ryan D Briscoe Runquist
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Annika M Moe
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Monica A Geber
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Carol Goodwillie
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA
| | | | | | - Elizabeth Elle
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Mark O Johnston
- Department of Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Susan Kalisz
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Richard H Ree
- Botany Department, Field Museum of Natural History, Chicago, IL, 60605, USA
| | - Risa D Sargent
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Mario Vallejo-Marin
- Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom
| | - Alice A Winn
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| |
Collapse
|
34
|
Nishida S, Hashimoto K, Kanaoka MM, Takakura KI, Nishida T. Variation in the strength of reproductive interference from an alien congener to a native species in Taraxacum. JOURNAL OF PLANT RESEARCH 2017; 130:125-134. [PMID: 27659681 DOI: 10.1007/s10265-016-0865-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
Reproductive interference (RI) may be a contributing factor to the displacement of native species by an alien congener, and RI strength has been shown theoretically to affect distributional relationships between species. Thus, variations in RI strength from alien to native species result in different consequences of invasions and efforts to conserve native species, but the variations have seldom been examined empirically. We therefore investigated RI strength variations from the alien species Taraxacum officinale and its hybrids to eight populations of native dandelions, four T. japonicum populations and two populations each of two subspecies of T. platycarpum. We examined the association between alien relative abundance and native seed set in field surveys, and we also performed hand-pollination experiments to investigate directly the sensitivity of native flowers to alien pollen. We found that the effect of alien relative abundance on native seed set of even the same native species could differ greatly in different regions, and that the sensitivity of native flowers to alien pollen was also dependent on region. Our results, together with those of previous studies, show that RI from the alien to the native species is strong in regions where the alien species outnumbers the native species and marginal where it does not; this result suggests that alien RI can critically affect distributional relationships between native and alien species. Our study highlights the importance of performing additional empirical investigations of RI strength variation and of giving due attention to alien RI in efforts to conserve regional native biodiversity.
Collapse
Affiliation(s)
- Sachiko Nishida
- Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Nagoya University Museum, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
| | - Keisuke Hashimoto
- Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Masahiro M Kanaoka
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Ko-Ichi Takakura
- School of Environmental Science, The University of Shiga Prefecture, Yasaka-cho, Hikone, 552-0057, Japan
| | - Takayoshi Nishida
- School of Environmental Science, The University of Shiga Prefecture, Yasaka-cho, Hikone, 552-0057, Japan
| |
Collapse
|
35
|
Weber MG, Strauss SY. Coexistence in Close Relatives: Beyond Competition and Reproductive Isolation in Sister Taxa. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2016. [DOI: 10.1146/annurev-ecolsys-112414-054048] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marjorie G. Weber
- Center for Population Biology, University of California, Davis, California 95616; ,
| | - Sharon Y. Strauss
- Center for Population Biology, University of California, Davis, California 95616; ,
- Department of Evolution and Ecology, University of California, Davis, California 95616
| |
Collapse
|
36
|
Koski MH, Ashman TL. Reproductive character displacement and environmental filtering shape floral variation between sympatric sister taxa. Evolution 2016; 70:2616-2622. [PMID: 27566693 DOI: 10.1111/evo.13042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 08/06/2016] [Accepted: 08/18/2016] [Indexed: 01/24/2023]
Abstract
Divergence in reproductive traits between closely related species that co-occur contributes to speciation by reducing interspecific gene flow. In flowering plants, greater floral divergence in sympatry than allopatry may reflect reproductive character displacement (RCD) by means of divergent pollinator-mediated selection or mating system evolution. However, environmental filtering (EF) would prevail for floral traits under stronger selection by abiotic factors than pollination, and lead to sympatric taxa being more phenotypically similar. We determine whether floral UV pigmentation and size show signatures of RCD or EF using a biogeographically informed sister taxa comparison. We determine whether 35 sister pairs in the Potentilleae tribe (Rosaceae) are allopatric or sympatric and confirm that sympatric sisters experience more similar bioclimatic conditions, an assumption of the EF hypothesis. We test whether interspecific differences are greater in allopatry or sympatry while accounting for divergence time. For UV pigmentation, sympatric sisters are more phenotypically similar than allopatric ones. For flower size, sympatric sisters show increased divergence with time since speciation but allopatric ones do not. We conclude that floral UV pigmentation shows a signature of EF, whereas flower size shows a signature of RCD. Discordant results between the traits suggest that the dominant selective agent differs between them.
Collapse
Affiliation(s)
- Matthew H Koski
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260. .,Current Address: Department of Biology, University of Virginia, Charlottesville, Virginia, 22904.
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
| |
Collapse
|
37
|
Castillo DM, Gibson AK, Moyle LC. Assortative mating and self-fertilization differ in their contributions to reinforcement, cascade speciation, and diversification. Curr Zool 2016; 62:169-181. [PMID: 29491904 PMCID: PMC5804227 DOI: 10.1093/cz/zow004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 01/07/2016] [Indexed: 11/14/2022] Open
Abstract
Cascade speciation and reinforcement can evolve rapidly when traits are pleiotropic and act as both signal/cue in nonrandom mating. Here, we examine the contribution of two key traits-assortative mating and self-fertilization-to reinforcement and (by extension) cascade speciation. First, using a population genetic model of reinforcement we find that both assortative mating and self-fertilization can make independent contributions to increased reproductive isolation, consistent with reinforcement. Self-fertilization primarily evolves due to its 2-fold transmission advantage when inbreeding depression (d) is lower (d < 0.45) but evolves as a function of the cost of hybridization under higher inbreeding depression (0.45 < d < 0.48). When both traits can evolve simultaneously, increased self-fertilization often prohibits the evolution of assortative mating. We infer that, under specific conditions, mating system transitions are more likely to lead to increased reproductive isolation and initiate cascade speciation, than assortative mating. Based on the results of our simulations, we hypothesized that transitions to self-fertilization could contribute to clade-wide diversification if reinforcement or cascade speciation is common. We tested this hypothesis with comparative data from two different groups. Consistent with our hypothesis, there was a trend towards uniparental reproduction being associated with increased diversification rate in the Nematode phylum. For the plant genus Mimulus, however, self-fertilization was associated with reduced diversification. Reinforcement driving speciation via transitions to self-fertilization might be short lived or unsustainable across macroevolutionary scales in some systems (some plants), but not others (such as nematodes), potentially due to differences in susceptibility to inbreeding depression and/or the ability to transition between reproductive modes.
Collapse
Affiliation(s)
- Dean M. Castillo
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
| | - Amanda K. Gibson
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
| | - Leonie C. Moyle
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
| |
Collapse
|
38
|
Briscoe Runquist R, Grossenbacher D, Porter S, Kay K, Smith J. Pollinator-mediated assemblage processes in California wildflowers. J Evol Biol 2016; 29:1045-58. [PMID: 26864797 DOI: 10.1111/jeb.12845] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 11/29/2022]
Abstract
Community assembly is the result of multiple ecological and evolutionary forces that influence species coexistence. For flowering plants, pollinators are often essential for plant reproduction and establishment, and pollinator-mediated interactions may influence plant community composition. Here, we use null models and community phylogenetic analyses of co-occurrence patterns to determine the role of pollinator-mediated processes in structuring plant communities dominated by congeners. We surveyed three species-rich genera (Limnanthes, Mimulus and Clarkia) with centres of diversity in the Sierra Nevada of California. Each genus contains species that co-flower and share pollinators, and each has a robust phylogeny. Within each genus, we surveyed 44-48 communities at three spatial scales, measured floral and vegetative traits and tested for segregation or aggregation of: (i) species, (ii) floral traits (which are likely to be influenced by pollinators), and (iii) vegetative traits (which are likely affected by other environmental factors). We detected both aggregation and segregation of floral traits that were uncorrelated with vegetative trait patterns; we infer that pollinators have shaped the community assembly although the mechanisms may be varied (competition, facilitation, or filtering). We also found that mating system differences may play an important role in allowing species co-occurrence. Together, it appears that pollinators influence community assemblage in these three clades.
Collapse
Affiliation(s)
- R Briscoe Runquist
- Department of Evolution and Ecology, University of California, Davis, Davis, CA, USA.,Department of Plant Biology, University of Minnesota, 250 Biological Sciences, St. Paul, MN, USA
| | - D Grossenbacher
- Department of Evolution and Ecology, University of California, Davis, Davis, CA, USA.,School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - S Porter
- Department of Evolution and Ecology, University of California, Davis, Davis, CA, USA.,School of Biological Sciences, Washington State University, Vancouver, Vancouver, WA, USA
| | - K Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - J Smith
- Department of Evolution and Ecology, University of California, Davis, Davis, CA, USA.,Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
| |
Collapse
|
39
|
Grossenbacher D, Briscoe Runquist RD, Goldberg EE, Brandvain Y. No association between plant mating system and geographic range overlap. AMERICAN JOURNAL OF BOTANY 2016; 103:110-117. [PMID: 26643886 DOI: 10.3732/ajb.1500078] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 06/15/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Automatic self-fertilization may influence the geography of speciation, promote reproductive isolation between incipient species, and lead to ecological differentiation. As such, selfing taxa are predicted to co-occur more often with their closest relatives than are outcrossing taxa. Despite suggestions that this pattern may be general, the extent to which mating system influences range overlap in close relatives has not been tested formally across a diverse group of plant species pairs. METHODS We tested for a difference in range overlap between species pairs for which zero, one, or both species are selfers, using data from 98 sister species pairs in 20 genera across 15 flowering plant families. We also used divergence time estimates from time-calibrated phylogenies to ask how range overlap changes with divergence time and whether this effect depends on mating system. KEY RESULTS We found no evidence that automatic self-fertilization influenced range overlap of closely related plant species. Sister pairs with more recent divergence times had modestly greater range overlap, but this effect did not depend on mating system. CONCLUSIONS The absence of a strong influence of mating system on range overlap suggests that mating system plays a minor or inconsistent role compared with many other mechanisms potentially influencing the co-occurrence of close relatives.
Collapse
Affiliation(s)
- Dena Grossenbacher
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108 USA
| | | | - Emma E Goldberg
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota 55108 USA
| | - Yaniv Brandvain
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108 USA
| |
Collapse
|
40
|
Bontrager M, Angert AL. Effects of range-wide variation in climate and isolation on floral traits and reproductive output of Clarkia pulchella. AMERICAN JOURNAL OF BOTANY 2016; 103:10-21. [PMID: 26362193 DOI: 10.3732/ajb.1500091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 05/28/2015] [Indexed: 05/11/2023]
Abstract
PREMISE OF THE STUDY Plant mating systems and geographic range limits are conceptually linked by shared underlying drivers, including landscape-level heterogeneity in climate and in species' abundance. Studies of how geography and climate interact to affect plant traits that influence mating system and population dynamics can lend insight to ecological and evolutionary processes shaping ranges. Here, we examined how spatiotemporal variation in climate affects reproductive output of a mixed-mating annual, Clarkia pulchella. We also tested the effects of population isolation and climate on mating-system-related floral traits across the range. METHODS We measured reproductive output and floral traits on herbarium specimens collected across the range of C. pulchella. We extracted climate data associated with specimens and derived a population isolation metric from a species distribution model. We then examined how predictors of reproductive output and floral traits vary among populations of increasing distance from the range center. Finally, we tested whether reproductive output and floral traits vary with increasing distance from the center of the range. KEY RESULTS Reproductive output decreased as summer precipitation decreased, and low precipitation may contribute to limiting the southern and western range edges of C. pulchella. High spring and summer temperatures are correlated with low herkogamy, but these climatic factors show contrasting spatial patterns in different quadrants of the range. CONCLUSIONS Limiting factors differ among different parts of the range. Due to the partial decoupling of geography and environment, examining relationships between climate, reproductive output, and mating-system-related floral traits reveals spatial patterns that might be missed when focusing solely on geographic position.
Collapse
Affiliation(s)
- Megan Bontrager
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Amy L Angert
- Departments of Botany and Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| |
Collapse
|
41
|
Luo Z, Duan T, Yuan S, Chen S, Bai X, Zhang D. Reproductive isolation between sympatric sister species, Mussaenda kwangtungensis and M. pubescens var. alba. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2015; 57:859-870. [PMID: 25545748 DOI: 10.1111/jipb.12325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/21/2014] [Indexed: 06/04/2023]
Abstract
Reproductive isolation defines the biological species concept and plays a key role in the formation and maintenance of species. The relative contributions of different isolating stages has been suggested to be closely associated with phylogenetic relatedness. Few studies have focused on the relative contributions of pre- versus post-zygotic mechanisms, and even fewer have been conducted under strict phylogenetic frameworks. Pre- and post-zygotic reproductive isolation stages have been investigated in the sister species Mussaenda kwangtungensis and M. pubescens var. alba. The two species have partly overlapping distribution ranges and flowering times, while the principal pollinators differed strikingly for them, demonstrating strong pre-zygotic isolations. Natural hybrids were detected by simple sequence repeat markers and their maternal parents were identified based on chloroplast gene sequences. Five out of 81 individuals were suggested to be hybrids that fall into the categories F2, BC1, and BC2 by the NewHybrids analysis. Interspecific crossings resulted in significantly reduced fruit set and seed germination rates. Phylogenetic analysis revealed short Kimura-2-parameter distance between M. kwangtungensis and M. pubescens var. alba. These findings strongly supported the hypothesis that for species with a closer phylogenetic relationship, pre-zygotic isolation plays an important part in limiting gene exchange in sympatric areas.
Collapse
Affiliation(s)
- Zhonglai Luo
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Tingting Duan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, 510650, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuai Yuan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, 510650, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Shi Chen
- Beneficial Insects Institute, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiufeng Bai
- Department of Cell Biology, the Third Military Medical University, Chongqing, China
| | - Dianxiang Zhang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, 510650, China
| |
Collapse
|
42
|
Norton NA, Fernando MTR, Herlihy CR, Busch JW. Reproductive character displacement shapes a spatially structured petal color polymorphism in Leavenworthia stylosa. Evolution 2015; 69:1191-207. [PMID: 25873258 DOI: 10.1111/evo.12659] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 03/30/2015] [Indexed: 11/28/2022]
Abstract
Character displacement is a potentially important process driving trait evolution and species diversification. Floral traits may experience character displacement in response to pollinator-mediated competition (ecological character displacement) or the risk of forming hybrids with reduced fitness (reproductive character displacement). We test these and alternative hypotheses to explain a yellow-white petal color polymorphism in Leavenworthia stylosa, where yellow morphs are spatially associated with a white-petaled congener (Leavenworthia exigua) that produces hybrids with complete pollen sterility. A reciprocal transplant experiment found limited evidence of local adaptation of yellow color morphs via increased survival and seed set. Pollinator observations revealed that Leavenworthia attract various pollinators that generally favor white petals and exhibit color constancy. Pollen limitation experiments showed that yellow petals do not alleviate competition for pollination. Interspecific pollinator movements were infrequent and low hybridization rates (∼0.40-0.85%) were found in each morph, with natural rates likely being lower. Regardless, hybridization rates were significantly higher in white morphs of L. stylosa, yielding a small selection coefficient of s = 0.0042 against this phenotype in sympatry with L. exigua. These results provide support for RCD as a mechanism contributing to the pattern of petal color polymorphism in L. stylosa.
Collapse
Affiliation(s)
- Nicholas A Norton
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, Washington, 99164
| | - M Thilina R Fernando
- Department of Biology, Evolution and Ecology Group, Middle Tennessee State University, PO Box 60, Murfreesboro,Tennessee, 37132
| | - Christopher R Herlihy
- Department of Biology, Evolution and Ecology Group, Middle Tennessee State University, PO Box 60, Murfreesboro,Tennessee, 37132
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, Washington, 99164.
| |
Collapse
|
43
|
Palma-Silva C, Cozzolino S, Paggi GM, Lexer C, Wendt T. Mating system variation and assortative mating of sympatric bromeliads (Pitcairnia spp.) endemic to neotropical inselbergs. AMERICAN JOURNAL OF BOTANY 2015; 102:758-764. [PMID: 26022489 DOI: 10.3732/ajb.1400513] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 04/24/2015] [Indexed: 06/04/2023]
Abstract
PREMISE OF THE STUDY The mating system is an important component of the complex set of reproductive isolation barriers causing plant speciation. However, empirical evidence showing that the mating system may promote reproductive isolation in co-occurring species is limited. The mechanisms by which the mating system can act as a reproductive isolation barrier are also largely unknown. METHODS Here we studied progeny arrays genotyped with microsatellites and patterns of stigma-anther separation (herkogamy) to understand the role of mating system shifts in promoting reproductive isolation between two hybridizing taxa with porous genomes, Pitcairnia albiflos and P. staminea (Bromeliaceae). KEY RESULTS In P. staminea, we detected increased selfing and reduced herkogamy in one sympatric relative to two allopatric populations, consistent with mating system shifts in sympatry acting to maintain the species integrity of P. staminea when in contact with P. albiflos. CONCLUSIONS Mating system variation is a result of several factors acting simultaneously in these populations. We report mating system shifts as one possible reproductive barrier between these species, acting in addition to numerous other prezygotic (i.e., flower phenology and pollination syndromes) and postzygotic barriers (Bateson-Dobzhansky-Muller genetic incompatibilities).
Collapse
Affiliation(s)
- Clarisse Palma-Silva
- Departamento de Ecologia, IB/UNESP, Rio Claro, SP, 13506-900 Brazil Instituto de Botânica, São Paulo, SP, 04301-012 Brazil
| | - Salvatore Cozzolino
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, 80126 Italy CNR Istituto per la Protezione Sostenibile delle Piante, Firenze, I-50019 Italy
| | | | - Christian Lexer
- Department of Biology, University of Fribourg, Fribourg, Switzerland Department of Botany and Biodiversity Research, University of Vienna, Vienna, A-1030 Austria
| | - Tânia Wendt
- Departamento de Botânica, CCS/IB/UFRJ, Rio de Janeiro, RJ, 21941-590 Brazil
| |
Collapse
|
44
|
Tokuda N, Hattori M, Abe K, Shinohara Y, Nagano Y, Itino T. Demonstration of pollinator-mediated competition between two native Impatiens species, Impatiens noli-tangere and I. textori (Balsaminaceae). Ecol Evol 2015; 5:1271-7. [PMID: 25859332 PMCID: PMC4377270 DOI: 10.1002/ece3.1431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 01/26/2015] [Accepted: 01/28/2015] [Indexed: 11/06/2022] Open
Abstract
Plant-plant interspecific competition via pollinators occurs when the flowering seasons of two or more plant species overlap and the pollinator fauna is shared. Negative sexual interactions between species (reproductive interference) through improper heterospecific pollen transfer have recently been reported between native and invasive species demonstrating pollination-driven competition. We focused on two native Impatiens species (I. noli-tangere and I. textori) found in Japan and examined whether pollinator-mediated plant competition occurs between them. We demonstrate that I. noli-tangere and I. textori share the same pollination niche (i.e., flowering season, pollinator fauna, and position of pollen on the pollinator's body). In addition, heterospecific pollen grains were deposited on most stigmas of both I. noli-tangere and I. textori flowers that were situated within 2 m of flowers of the other species resulting in depressed fruit set. Further, by hand-pollination experiments, we show that when as few as 10% of the pollen grains are heterospecific, fruit set is decreased to less than half in both species. These results show that intensive pollinator-mediated competition occurs between I. noli-tangere and I. textori. This study suggests that intensive pollinator-mediated competition occurs in the wild even when interacting species are both native and not invasive.
Collapse
Affiliation(s)
- Nanako Tokuda
- Department of Biology, Faculty of Science, Shinshu University Nagano, Japan
| | - Mitsuru Hattori
- Department of Biology, Faculty of Science, Shinshu University Nagano, Japan
| | - Kota Abe
- Department of Biology, Faculty of Science, Shinshu University Nagano, Japan
| | | | - Yusuke Nagano
- Department of Biology, Faculty of Science, Shinshu University Nagano, Japan
| | - Takao Itino
- Department of Biology, Faculty of Science, Shinshu University Nagano, Japan ; Institute of Mountain Science, Shinshu University Nagano, Japan
| |
Collapse
|
45
|
Beans CM, Roach DA. An invasive plant alters pollinator-mediated phenotypic selection on a native congener. AMERICAN JOURNAL OF BOTANY 2015; 102:50-57. [PMID: 25587147 DOI: 10.3732/ajb.1400385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED • PREMISE OF STUDY Recent studies suggest that invasive plants compete reproductively with native plants by reducing the quantity or quality of pollinator visits. Although these studies have revealed ecological consequences of pollinator-mediated competition between invasive and native plants, the evolutionary outcomes of these interactions remain largely unexplored.• METHODS We studied the ecological and evolutionary impact of pollinator-mediated competition with an invasive jewelweed, Impatiens glandulifera, on a co-occurring native congener, I. capensis. Using a pollinator choice experiment, a hand pollination experiment, and a selection analysis, we addressed the following questions: (1) Do native pollinators show preference for the invasive or native jewelweed, and do they move between the two species? (2) Does invasive jewelweed pollen inhibit seed production in the native plant? (3) Does the invasive jewelweed alter phenotypic selection on the native plant's floral traits?• KEY RESULTS The pollinator choice experiment showed that pollinators strongly preferred the invasive jewelweed. The hand pollination experiment demonstrated that invasive pollen inhibited seed production in the native plant. The selection analysis showed that the presence of the invasive jewelweed altered phenotypic selection on corolla height in the native plant.• CONCLUSIONS Invasive plants have the potential to alter phenotypic selection on floral traits in native plant populations. If native plants can evolve in response to this altered selection pressure, the evolution of floral traits may play an important role in permitting long-term coexistence of native and invasive plants.
Collapse
Affiliation(s)
- Carolyn M Beans
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia 22904-4328, USA
| | - Deborah A Roach
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia 22904-4328, USA
| |
Collapse
|
46
|
Peterson ML, Kay KM. Mating System Plasticity Promotes Persistence and Adaptation of Colonizing Populations of Hermaphroditic Angiosperms. Am Nat 2015; 185:28-43. [DOI: 10.1086/679107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
47
|
Miller EL, Greig D. Spore germination determines yeast inbreeding according to fitness in the local environment. Am Nat 2014; 185:291-301. [PMID: 25616146 DOI: 10.1086/679347] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Gene combinations conferring local fitness may be destroyed by mating with individuals that are adapted to a different environment. This form of outbreeding depression provides an evolutionary incentive for self-fertilization. We show that the yeast Saccharomyces paradoxus tends to self-fertilize when it is well adapted to its local environment but tends to outcross when it is poorly adapted. This behavior could preserve combinations of genes when they are beneficial and break them up when they are not, thereby helping adaptation. Haploid spores must germinate before mating, and we found that fitter spores had higher rates of germination across a 24-hour period, increasing the probability that they mate with germinated spores from the same meiotic tetrad. The ability of yeast spores to detect local conditions before germinating and mating suggests the novel possibility that these gametes directly sense their own adaptation and plastically adjust their breeding strategy accordingly.
Collapse
Affiliation(s)
- Eric L Miller
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany
| | | |
Collapse
|
48
|
Grossenbacher DL, Stanton ML. Pollinator-mediated competition influences selection for flower-color displacement in sympatric monkeyflowers. AMERICAN JOURNAL OF BOTANY 2014; 101:1915-24. [PMID: 25366857 DOI: 10.3732/ajb.1400204] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
PREMISE OF STUDY When coflowering plant species share pollinators, pollinator-mediated competition may favor divergent floral characters associated with pollinator attraction. One potential outcome of this process is that sympatric populations will display increased divergence in floral traits compared with allopatric populations. We developed a new system to study the pattern and process of character displacement. In the central Sierra Nevada of California, USA, Mimulus bicolor is a spring wildflower with two flower-color morphs, one of which resembles coflowering M. guttatus. METHODS We documented a fine-scale geographic pattern of character displacement in sympatric and allopatric patches and, using experimental arrays, measured seed set in M. bicolor color morphs in the presence versus absence of M. guttatus. KEY RESULTS In sympatric arrays yellow, guttatus-like M. bicolor morphs had lower relative fitness (0.35 ± 0.05) and reduced conspecific pollen deposition compared with the distinct alternative morph, whereas in allopatric arrays yellow, guttatus-like morphs were occasionally strongly favored. CONCLUSIONS Pollinator-mediated competition with M. guttatus is consistent with ecological character displacement in M. bicolor and likely contributes to a geographic pattern of character displacement.
Collapse
Affiliation(s)
- Dena L Grossenbacher
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108 USA
| | - Maureen L Stanton
- Department of Evolution and Ecology, Center for Population Biology, University of California, Davis, California 95616 USA
| |
Collapse
|
49
|
Ferris KG, Sexton JP, Willis JH. Speciation on a local geographic scale: the evolution of a rare rock outcrop specialist in Mimulus. Philos Trans R Soc Lond B Biol Sci 2014; 369:20140001. [PMID: 24958929 PMCID: PMC4071529 DOI: 10.1098/rstb.2014.0001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciation has occurred in this manner. A recently described morphological species in the yellow monkey flowers, Mimulus filicifolius, is an excellent candidate for local speciation because of its highly restricted geographical range. Mimulus filicifolius was formerly identified as a population of M. laciniatus due to similar lobed leaf morphology and rocky outcrop habitat. To investigate whether M. filicifolius is genetically divergent and reproductively isolated from M. laciniatus, we examined patterns of genetic diversity in ten nuclear and eight microsatellite loci, and hybrid fertility in M. filicifolius and its purported close relatives: M. laciniatus, M. guttatus and M. nasutus. We found that M. filicifolius is genetically divergent from the other species and strongly reproductively isolated from M. laciniatus. We conclude that M. filicifolius is an independent rock outcrop specialist despite being morphologically and ecologically similar to M. laciniatus, and that its small geographical range nested within other wide-ranging members of the M. guttatus species complex is consistent with local speciation.
Collapse
Affiliation(s)
- Kathleen G Ferris
- Department of Biology, Duke University, 125 Science Drive, Durham, NC 27708, USA
| | - Jason P Sexton
- School of Natural Sciences, University of California Merced, 5200 North Lake Road, Merced, CA 95343, USA
| | - John H Willis
- Department of Biology, Duke University, 125 Science Drive, Durham, NC 27708, USA
| |
Collapse
|
50
|
Devaux C, Lepers C, Porcher E. Constraints imposed by pollinator behaviour on the ecology and evolution of plant mating systems. J Evol Biol 2014; 27:1413-30. [PMID: 24750302 DOI: 10.1111/jeb.12380] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/31/2014] [Accepted: 03/20/2014] [Indexed: 01/10/2023]
Abstract
Most flowering plants rely on pollinators for their reproduction. Plant-pollinator interactions, although mutualistic, involve an inherent conflict of interest between both partners and may constrain plant mating systems at multiple levels: the immediate ecological plant selfing rates, their distribution in and contribution to pollination networks, and their evolution. Here, we review experimental evidence that pollinator behaviour influences plant selfing rates in pairs of interacting species, and that plants can modify pollinator behaviour through plastic and evolutionary changes in floral traits. We also examine how theoretical studies include pollinators, implicitly or explicitly, to investigate the role of their foraging behaviour in plant mating system evolution. In doing so, we call for more evolutionary models combining ecological and genetic factors, and additional experimental data, particularly to describe pollinator foraging behaviour. Finally, we show that recent developments in ecological network theory help clarify the impact of community-level interactions on plant selfing rates and their evolution and suggest new research avenues to expand the study of mating systems of animal-pollinated plant species to the level of the plant-pollinator networks.
Collapse
Affiliation(s)
- C Devaux
- Institut des Sciences de l'Evolution de Montpellier, UMR 5554, Université Montpellier 2, Montpellier, France
| | | | | |
Collapse
|