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Solís-Montero L, Vallejo-Marín M. Does the morphological fit between flowers and pollinators affect pollen deposition? An experimental test in a buzz-pollinated species with anther dimorphism. Ecol Evol 2017; 7:2706-2715. [PMID: 28428861 PMCID: PMC5395427 DOI: 10.1002/ece3.2897] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/14/2017] [Accepted: 02/20/2017] [Indexed: 11/21/2022] Open
Abstract
Some pollination systems, such as buzz‐pollination, are associated with floral morphologies that require a close physical interaction between floral sexual organs and insect visitors. In these systems, a pollinator's size relative to the flower may be an important feature determining whether the visitor touches both male and female sexual organs and thus transfers pollen between plants efficiently. To date, few studies have addressed whether in fact the “fit” between flower and pollinator influences pollen transfer, particularly among buzz‐pollinated species. Here we use Solanum rostratum, a buzz‐pollinated plant with dimorphic anthers and mirror‐image flowers, to investigate whether the morphological fit between the pollinator's body and floral morphology influences pollen deposition. We hypothesized that when the size of the pollinator matches the separation between the sexual organs in a flower, more pollen should be transferred to the stigma than when the visitor is either too small or too big relative to the flower. To test this hypothesis, we exposed flowers of S. rostratum with varying levels of separation between sexual organs, to bumblebees (Bombus terrestris) of different sizes. We recorded the number of visits received, pollen deposition, and fruit and seed production. We found higher pollen deposition when bees were the same size or bigger than the separation between anther and stigma within a flower. We found a similar, but not statistically significant pattern for fruit set. In contrast, seed set was more likely to occur when the size of the flower exceeded the size of the bee, suggesting that other postpollination processes may be important in translating pollen receipt to seed set. Our results suggest that the fit between flower and pollinator significantly influences pollen deposition in this buzz‐pollinated species. We speculate that in buzz‐pollinated species where floral morphology and pollinators interact closely, variation in the visitor's size may determine whether it acts mainly as a pollinator or as a pollen thief (i.e., removing pollen rewards but contributing little to pollen deposition and fertilization).
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Affiliation(s)
- Lislie Solís-Montero
- Biological and Environmental Sciences School of Natural Sciences University of Stirling Stirling UK.,Present address: Lislie Solís-Montero, CONACYT. El Colegio de la Frontera Sur (ECOSUR) Unidad Tapachula Tapachula Chiapas México
| | - Mario Vallejo-Marín
- Biological and Environmental Sciences School of Natural Sciences University of Stirling Stirling UK
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52
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Armbruster WS. The specialization continuum in pollination systems: diversity of concepts and implications for ecology, evolution and conservation. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12783] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- William Scott Armbruster
- School of Biological Sciences University of Portsmouth PortsmouthPO1 2DY UK
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK99775‐7000 USA
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53
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Sex and the shifting biodiversity dynamics of marine animals in deep time. Proc Natl Acad Sci U S A 2016; 113:14073-14078. [PMID: 27821755 DOI: 10.1073/pnas.1610726113] [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] [Indexed: 01/28/2023] Open
Abstract
The fossil record of marine animals suggests that diversity-dependent processes exerted strong control on biodiversification: after the Ordovician Radiation, genus richness did not trend for hundreds of millions of years. However, diversity subsequently rose dramatically in the Cretaceous and Cenozoic (145 million years ago-present), indicating that limits on diversification can be overcome by ecological or evolutionary change. Here, we show that the Cretaceous-Cenozoic radiation was driven by increased diversification in animals that transfer sperm between adults during fertilization, whereas animals that broadcast sperm into the water column have not changed significantly in richness since the Late Ordovician (∼450 million years ago). We argue that the former group radiated in part because directed sperm transfer permits smaller population sizes and additional modes of prezygotic isolation, as has been argued previously for the coincident radiation of angiosperms. Directed sperm transfer tends to co-occur with many ecological traits, such as a predatory lifestyle. Ecological specialization likely operated synergistically with mode of fertilization in driving the diversification that began during the Mesozoic marine revolution. Plausibly, the ultimate driver of diversification was an increase in food availability, but its effects on the fauna were regulated by fundamental reproductive and ecological traits.
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54
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Hembry DH, Althoff DM. Diversification and coevolution in brood pollination mutualisms: Windows into the role of biotic interactions in generating biological diversity. AMERICAN JOURNAL OF BOTANY 2016; 103:1783-1792. [PMID: 27765775 PMCID: PMC6110533 DOI: 10.3732/ajb.1600056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/10/2016] [Indexed: 05/05/2023]
Abstract
Brood pollination mutualisms-interactions in which specialized insects are both the pollinators (as adults) and seed predators (as larvae) of their host plants-have been influential study systems for coevolutionary biology. These mutualisms include those between figs and fig wasps, yuccas and yucca moths, leafflowers and leafflower moths, globeflowers and globeflower flies, Silene plants and Hadena and Perizoma moths, saxifrages and Greya moths, and senita cacti and senita moths. The high reciprocal diversity and species-specificity of some of these mutualisms have been cited as evidence that coevolution between plants and pollinators drives their mutual diversification. However, the mechanisms by which these mutualisms diversify have received less attention. In this paper, we review key hypotheses about how these mutualisms diversify and what role coevolution between plants and pollinators may play in this process. We find that most species-rich brood pollination mutualisms show significant phylogenetic congruence at high taxonomic scales, but there is limited evidence for the processes of both cospeciation and duplication, and there are no unambiguous examples known of strict-sense contemporaneous cospeciation. Allopatric speciation appears important across multiple systems, particularly in the insects. Host-shifts appear to be common, and widespread host-shifts by pollinators may displace other pollinator lineages. There is relatively little evidence for a "coevolution through cospeciation" model or that coevolution promotes speciation in these systems. Although we have made great progress in understanding the mechanisms by which brood pollination mutualisms diversify, many opportunities remain to use these intriguing symbioses to understand the role of biotic interactions in generating biological diversity.
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Affiliation(s)
- David H Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA
| | - David M Althoff
- Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244 USA
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55
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Svensson GP, Raguso RA, Flatz R, Smith CI. Floral scent of Joshua trees (Yucca brevifolia sensu lato): Divergence in scent profiles between species but breakdown of signal integrity in a narrow hybrid zone. AMERICAN JOURNAL OF BOTANY 2016; 103:1793-1802. [PMID: 27578627 DOI: 10.3732/ajb.1600033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/13/2016] [Indexed: 05/14/2023]
Abstract
PREMISE OF THE STUDY The role of floral scent in facilitating reproductive isolation between closely related plants remains poorly understood. Yucca brevifolia and Yucca jaegeriana are pollinated by different moth species in allopatry, but in a narrow contact zone, pollinator-host specificity breaks down, resulting in hybridization between species. We explored the chemical basis for reproductive isolation and hybridization in these Joshua trees by characterizing the floral scent of each species in allopatry, analyzing scent profiles from trees in the contact zone, and matching these data with genotypic and phenotypic data. METHODS We analyzed floral volatiles using gas chromatography-mass spectrometry, tested for species divergence of scent profiles and classified trees in the contact zone as hybrid or either parental species. We used floral and vegetative morphological data and genotypic data to classify trees and analyzed whether certain trait combinations were more correlated than others with respect to assignment of trees and whether frequencies of classified tree types differed depending on which data set was used. KEY RESULTS The Joshua tree floral scent included oxygenated 8-carbon compounds not reported for other yuccas. The two species differed (P < 0.001) in scent profiles. In the contact zone, many hybrids were found, and phenotypic traits were generally weakly correlated, which may be explained by extensive gene flow between species or by exposure to different selection pressures. CONCLUSIONS Although the two Joshua tree species produce distinct floral scent profiles, it is insufficient to prevent attraction of associated pollinators to both hosts. Instead, floral morphology may be the key trait mediating gene flow between species.
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Affiliation(s)
- Glenn P Svensson
- Department of Biology, Lund University, Solvegatan 37, SE-22362 Lund Sweden
| | - Robert A Raguso
- Department of Neurobiology and Behavior, 215 Tower Road, Cornell University, Ithaca, New York 14853 USA
| | - Ramona Flatz
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
| | - Christopher I Smith
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
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56
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Weber MG, Mitko L, Eltz T, Ramírez SR. Macroevolution of perfume signalling in orchid bees. Ecol Lett 2016; 19:1314-1323. [PMID: 27581155 DOI: 10.1111/ele.12667] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/28/2016] [Accepted: 07/24/2016] [Indexed: 11/28/2022]
Abstract
Theory predicts that both stabilising selection and diversifying selection jointly contribute to the evolution of sexual signalling traits by (1) maintaining the integrity of communication signals within species and (2) promoting the diversification of traits among lineages. However, for many important signalling traits, little is known about whether these dynamics translate into predictable macroevolutionary signatures. Here, we test for macroevolutionary patterns consistent with sexual signalling theory in the perfume signals of neotropical orchid bees, a group well studied for their chemical sexual communication. Our results revealed both high species-specificity and elevated rates of evolution in perfume signals compared to nonsignalling traits. Perfume complexity was correlated with the number of congeners in a species' range, suggesting that perfume evolution may be tied to the remarkably high number of orchid bee species coexisting together in some neotropical communities. Finally, sister-pair comparisons were consistent with both rapid divergence at speciation and character displacement upon secondary contact. Together, our results provide new insight into the macroevolution of sexual signalling in insects.
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Affiliation(s)
- Marjorie G Weber
- Center for Population Biology, University of California, Davis, CA, 95616, USA.
| | - Lukasz Mitko
- Department of Animal Ecology, Evolution and Biodiversity, University of Bochum, 44780, Bochum, Germany
| | - Thomas Eltz
- Department of Animal Ecology, Evolution and Biodiversity, University of Bochum, 44780, Bochum, Germany
| | - Santiago R Ramírez
- Center for Population Biology, University of California, Davis, CA, 95616, USA. .,Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA.
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57
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Martínez-Adriano CA, Jurado E, Flores J, González-Rodríguez H, Cuéllar-Rodríguez G. Flower, fruit phenology and flower traits in Cordia boissieri (Boraginaceae) from northeastern Mexico. PeerJ 2016; 4:e2033. [PMID: 27231656 PMCID: PMC4878375 DOI: 10.7717/peerj.2033] [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: 11/19/2015] [Accepted: 04/21/2016] [Indexed: 11/21/2022] Open
Abstract
We characterized variations in Cordia boissieri flowers and established if these variations occur between plants or between flowering events. Flowering and fruiting was measured for 256 plants. A GLM test was used to determine the relationship between flowering and fruit set processes and rainfall. We performed measurements of floral traits to detect variations within the population and between flowering events. The position of the anthers with respect to the ovary was determined in 1,500 flowers. Three out of four flowering events of >80% C. boissieri plants occurred after rainfall events. Only one flowering event occurred in a drought. Most plants flowered at least twice a year. The overlapping of flowering and fruiting only occurred after rainfall. Anthesis lasted three-to-five days, and there were two flower morphs. Half of the plants had longistylus and half had brevistylus flowers. Anacahuita flower in our study had 1-4 styles; 2-9 stamens; 6.5-41.5 mm long corolla; sepals from 4.5-29.5 mm in length; a total length from 15.5-59 mm; a corolla diameter from 10.5-77 mm. The nectar guide had a diameter from 5-30.5 mm; 4-9 lobes; and 5 distinguishable nectar guide colors. The highest variation of phenotypic expression was observed between plants.
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Affiliation(s)
| | - Enrique Jurado
- Facultad de Ciencias Forestales, Universidad Autonoma de Nuevo Leon, Linares Nuevo Leon, Mexico
| | - Joel Flores
- Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnologica, San Luis Potosi San Luis Potosi, Mexico
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58
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O'Meara BC, Smith SD, Armbruster WS, Harder LD, Hardy CR, Hileman LC, Hufford L, Litt A, Magallón S, Smith SA, Stevens PF, Fenster CB, Diggle PK. Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity. Proc Biol Sci 2016; 283:20152304. [PMID: 27147092 PMCID: PMC4874697 DOI: 10.1098/rspb.2015.2304] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 04/08/2016] [Indexed: 12/28/2022] Open
Abstract
Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years.
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Affiliation(s)
- Brian C O'Meara
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Stacey D Smith
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Lawrence D Harder
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | | | - Lena C Hileman
- Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA
| | - Larry Hufford
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Amy Litt
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA The New York Botanical Garden, Bronx, NY 10459, USA
| | - Susana Magallón
- Instituto de Biología, Universidad Nacional Autónoma de México, México DF 04510, México
| | - Stephen A Smith
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Charles B Fenster
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA
| | - Pamela K Diggle
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043, USA
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59
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Benadi G. Requirements for plant coexistence through pollination niche partitioning. Proc Biol Sci 2016; 282:rspb.2015.0117. [PMID: 26108627 DOI: 10.1098/rspb.2015.0117] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Plant-pollinator interactions are often thought to have been a decisive factor in the diversification of flowering plants, but to be of little or no importance for the maintenance of existing plant diversity. In a recent opinion paper, Pauw (2013 Trends Ecol. Evol. 28, 30-37. (doi:10.1016/j.tree.2012.07.019)) challenged this view by proposing a mechanism of diversity maintenance based on pollination niche partitioning. In this article, I investigate under which conditions the mechanism suggested by Pauw can promote plant coexistence, using a mathematical model of plant and pollinator population dynamics. Numerical simulations show that this mechanism is most effective when the costs of searching for flowers are low, pollinator populations are strongly limited by resources other than pollen and nectar, and plant-pollinator interactions are sufficiently specialized. I review the empirical literature on these three requirements, discuss additional factors that may be important for diversity maintenance through pollination niche partitioning, and provide recommendations on how to detect this coexistence mechanism in natural plant communities.
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Affiliation(s)
- Gita Benadi
- Biometry and Environmental System Analysis, University of Freiburg, Tennenbacherstrasse 4, 79106 Freiburg im Breisgau, Germany
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60
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Ren MX. El curso superior del río más grande del sur de china como un «frente evolutivo» de plantas tropicales: evidencia del género endémico de Asia Hiptage (Malpighiaceae). COLLECTANEA BOTANICA 2015. [DOI: 10.3989/collectbot.2015.v34.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
El hotspot de biodiversidad en las fronteras de las provincias Guizhou-Yunnan- Guangxi es un centro de distribución de plantas tropicales en China. Se extiende por toda la cuenca alta del río Zhujiang, el mayor río del sur de China. En este artículo, se explora el papel del río en la propagación y la diversificación de las plantas tropicales en este área, usando el género endémico de Asia Hiptage Gaertn. (Malpighiaceae) como ejemplo. Se reconocen dos centros de diversidad y endemismo de Hiptage: la Península Indochina y el curso superior del río Zhujiang (UZJ). El índice de endemismo ajustado al área indica UZJ como la región más importante de distribución de especies endémicas, ya que, aunque UZJ tiene un área muy pequeña (~210.000 km2), seis de un total de siete especies son estrictamente endémicas. UZJ está situado en el extremo norte del área de distribución de Hiptage, lo que resultó principalmente de la disposición noroeste-sureste de los sistemas fluviales de UZJ, que facilitaron la expansión y diferenciación hacia el norte de este género tropical. Los paisajes de piedra caliza altamente fragmentados en esta región han contribuido al aislamiento de hábitat y pueden ser el principal factor para el origen de estas especies endémicas. Hiptage también se distingue por su sistema de polinización altamente especializado, con flores de imagen especular, lo que probablemente facilita la diversificación de las especies a través del aislamiento de la polinización. Otros estudios también encontraron que UZJ es un importante centro de diversificación de las familias de plantas tropicales Begoniaceae y Gesneriaceae. Por consiguiente, se concluye que UZJ es un «frente evolutivo» de plantas tropicales en China, lo que contribuye de manera significativa al origen y mantenimiento de la biodiversidad única en la zona.
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61
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Serrano-Serrano ML, Perret M, Guignard M, Chautems A, Silvestro D, Salamin N. Decoupled evolution of floral traits and climatic preferences in a clade of Neotropical Gesneriaceae. BMC Evol Biol 2015; 15:247. [PMID: 26555183 PMCID: PMC4641406 DOI: 10.1186/s12862-015-0527-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 10/30/2015] [Indexed: 11/12/2022] Open
Abstract
Background Major factors influencing the phenotypic diversity of a lineage can be recognized by characterizing the extent and mode of trait evolution between related species. Here, we compared the evolutionary dynamics of traits associated with floral morphology and climatic preferences in a clade composed of the genera Codonanthopsis, Codonanthe and Nematanthus (Gesneriaceae). To test the mode and specific components that lead to phenotypic diversity in this group, we performed a Bayesian phylogenetic analysis of combined nuclear and plastid DNA sequences and modeled the evolution of quantitative traits related to flower shape and size and to climatic preferences. We propose an alternative approach to display graphically the complex dynamics of trait evolution along a phylogenetic tree using a wide range of evolutionary scenarios. Results Our results demonstrated heterogeneous trait evolution. Floral shapes displaced into separate regimes selected by the different pollinator types (hummingbirds versus insects), while floral size underwent a clade-specific evolution. Rates of evolution were higher for the clade that is hummingbird pollinated and experienced flower resupination, compared with species pollinated by bees, suggesting a relevant role of plant-pollinator interactions in lowland rainforest. The evolution of temperature preferences is best explained by a model with distinct selective regimes between the Brazilian Atlantic Forest and the other biomes, whereas differentiation along the precipitation axis was characterized by higher rates, compared with temperature, and no regime or clade-specific patterns. Conclusions Our study shows different selective regimes and clade-specific patterns in the evolution of morphological and climatic components during the diversification of Neotropical species. Our new graphical visualization tool allows the representation of trait trajectories under parameter-rich models, thus contributing to a better understanding of complex evolutionary dynamics. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0527-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Martha Liliana Serrano-Serrano
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics, Quartier Sorge, 1015, Lausanne, Switzerland.
| | - Mathieu Perret
- Conservatoire et Jardin botaniques de la Ville de Genève and Laboratory of Plant Systematics and Biodiversity, University of Geneva, Chemin de l'Impératrice, 1, 1292 , Chambésy, Geneva, Switzerland.
| | - Maïté Guignard
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland.
| | - Alain Chautems
- Conservatoire et Jardin botaniques de la Ville de Genève and Laboratory of Plant Systematics and Biodiversity, University of Geneva, Chemin de l'Impératrice, 1, 1292 , Chambésy, Geneva, Switzerland.
| | - Daniele Silvestro
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics, Quartier Sorge, 1015, Lausanne, Switzerland. .,Department of Plant and Environmental Sciences, University of Gothenburg, Carl Skottsbergs gata 22B, 413 19, Gothenburg, Sweden.
| | - Nicolas Salamin
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics, Quartier Sorge, 1015, Lausanne, Switzerland.
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62
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Bartoš M, Janeček S. Pollinator-induced twisting of flowers sidesteps floral architecture constraints. Curr Biol 2015; 24:R793-5. [PMID: 25202867 DOI: 10.1016/j.cub.2014.07.056] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Specific pollen placement by zygomorphic flowers on pollinators is one of the key innovations of angiosperm evolution [1]. In most phylogenetic lineages that have evolved zygomorphic flowers, reproductive organs are positioned either in the lower or upper part of the flower. Although these specific positions largely enhance pollen economy, they also represent architectural constraints such that flowers are able to place pollen only on the dorsal or ventral part of pollinators' bodies [2]. Such constraints can lead to interspecific pollen placement in situations where phylogenetically related species with the same floral architecture share pollinators [3].
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Affiliation(s)
- Michael Bartoš
- Institute of Botany, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-379 82 Třeboň, Czech Republic.
| | - Stěpán Janeček
- Institute of Botany, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-379 82 Třeboň, Czech Republic; Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, CZ-128 44 Praha 2, Czech Republic
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63
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Rodríguez-Gironés MA, Sun S, Santamaría L. Passive partner choice through exploitation barriers. Evol Ecol 2015. [DOI: 10.1007/s10682-014-9738-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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64
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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.
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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.
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65
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Gómez JM, Perfectti F, Lorite J. The role of pollinators in floral diversification in a clade of generalist flowers. Evolution 2015; 69:863-78. [PMID: 25757195 DOI: 10.1111/evo.12632] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/26/2015] [Indexed: 11/30/2022]
Abstract
Pollinator-mediated evolutionary divergence has seldom been explored in generalist clades because it is assumed that pollinators in those clades exert weak and conflicting selection. We investigate whether pollinators shape floral diversification in a pollination generalist plant genus, Erysimum. Species from this genus have flowers that appeal to broad assemblages of pollinators. Nevertheless, we recently reported that it is possible to sort plant species into pollination niches varying in the quantitative composition of pollinators. We test here whether floral characters of Erysimum have evolved as a consequence of shifts among pollination niches. For this, we quantified the evolutionary lability of the floral traits and their phylogenetic association with pollination niches. As with pollination niches, Erysimum floral traits show weak phylogenetic signal. Moreover, floral shape and color are phylogenetically associated with pollination niche. In particular, plants belonging to a pollination niche dominated by long-tongued large bees have lilac corollas with parallel petals. Further analyses suggest, however, that changes in color preceded changes in pollination niche. Pollinators seem to have driven the evolution of corolla shape, whereas the association between pollination niche and corolla color has probably arisen by lilac-flowered Erysimum moving toward certain pollination niches for other adaptive reasons.
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Affiliation(s)
- José M Gómez
- Dpto de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Aridas (EEZA-CSIC), E-04120, Almería, Spain; Dpto de Ecología, Universidad de Granada, E-18071, Granada, Spain.
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66
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Blanco-Pastor JL, Ornosa C, Romero D, Liberal IM, Gómez JM, Vargas P. Bees explain floral variation in a recent radiation of Linaria. J Evol Biol 2015; 28:851-63. [DOI: 10.1111/jeb.12609] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/15/2015] [Accepted: 02/20/2015] [Indexed: 01/06/2023]
Affiliation(s)
- J. L. Blanco-Pastor
- Real Jardín Botánico de Madrid (RJB-CSIC); Madrid Spain
- Department of Biological and Environmental Sciences; University of Gothenburg; Göteborg Sweden
| | - C. Ornosa
- Departmento de Zoología y Antropología Física; Universidad Complutense de Madrid; Madrid Spain
| | - D. Romero
- Departmento de Zoología y Antropología Física; Universidad Complutense de Madrid; Madrid Spain
| | - I. M. Liberal
- Real Jardín Botánico de Madrid (RJB-CSIC); Madrid Spain
| | - J. M. Gómez
- Departmento de Ecología Funcional y Evolutiva; Estación Experimental de Zonas Áridas (EEZA-CSIC); Almería Spain
- Departamento de Ecología; Universidad de Granada; Granada Spain
| | - P. Vargas
- Real Jardín Botánico de Madrid (RJB-CSIC); Madrid Spain
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67
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Leles B, Chaves AV, Russo P, Batista JAN, Lovato MB. Genetic structure is associated with phenotypic divergence in floral traits and reproductive investment in a high-altitude orchid from the Iron Quadrangle, southeastern Brazil. PLoS One 2015; 10:e0120645. [PMID: 25756994 PMCID: PMC4355488 DOI: 10.1371/journal.pone.0120645] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/25/2015] [Indexed: 12/03/2022] Open
Abstract
Knowledge of the role of Neotropical montane landscapes in shaping genetic connectivity and local adaptation is essential for understanding the evolutionary processes that have shaped the extraordinary species diversity in these regions. In the present study, we examined the landscape genetics, estimated genetic diversity, and explored genetic relationships with morphological variability and reproductive strategies in seven natural populations of Cattleya liliputana (Orchidaceae). Nuclear microsatellite markers were used for genetic analyses. Spatial Bayesian clustering and population-based analyses revealed significant genetic structuring and high genetic diversity (He = 0.733 ± 0.03). Strong differentiation was found between populations over short spatial scales (FST = 0.138, p < 0.001), reflecting the landscape discontinuity and isolation. Monmonier´s maximum difference algorithm, Bayesian analysis on STRUCTURE and principal component analysis identified one major genetic discontinuity between populations. Divergent genetic groups showed phenotypic divergence in flower traits and reproductive strategies. Increased sexual reproductive effort was associated with rock outcrop type and may be a response to adverse conditions for growth and vegetative reproduction. Here we discuss the effect of restricted gene flow, local adaptation and phenotypic plasticity as drivers of population differentiation in Neotropical montane rock outcrops.
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Affiliation(s)
- Bruno Leles
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Anderson V. Chaves
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Philip Russo
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - João A. N. Batista
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Maria Bernadete Lovato
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
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68
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Scopece G, Schiestl FP, Cozzolino S. Pollen transfer efficiency and its effect on inflorescence size in deceptive pollination strategies. PLANT BIOLOGY (STUTTGART, GERMANY) 2015; 17:545-550. [PMID: 25040501 DOI: 10.1111/plb.12224] [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: 02/04/2014] [Accepted: 05/16/2014] [Indexed: 06/03/2023]
Abstract
Pollination systems differ in pollen transfer efficiency, a variable that may influence the evolution of flower number. Here we apply a comparative approach to examine the link between pollen transfer efficiency and the evolution of inflorescence size in food and sexually deceptive orchids. We examined pollination performance in nine food-deceptive, and eight sexually deceptive orchids by recording pollen removal and deposition in the field. We calculated correlations between reproductive success and flower number (as a proxy for resources allocated during reproductive process), and directional selection differentials were estimated on flower number for four species. Results indicate that sexually deceptive species experience decreased pollen loss compared to food-deceptive species. Despite producing fewer flowers, sexually deceptive species attained levels of overall pollination success (through male and female function) similar to food-deceptive species. Furthermore, a positive correlation between flower number and pollination success was observed in food-deceptive species, but this correlation was not detected in sexually deceptive species. Directional selection differentials for flower number were significantly higher in food compared to sexually deceptive species. We suggest that pollination systems with more efficient pollen transfer and no correlation between pollination success and number of flowers produced, such as sexual deception, may allow the production of inflorescences with fewer flowers that permit the plant to allocate fewer resources to floral displays and, at the same time, limit transpiration. This strategy can be particularly important for ecological success in Mediterranean water-deprived habitats, and might explain the high frequency of sexually deceptive species in these specialised ecosystems.
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Affiliation(s)
- G Scopece
- Department of Biology, University Federico II, Complesso Universitario MSA, Naples, Italy; Institute for Plant Protection, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (FI), Italy
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69
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Gómez JM, Perfectti F, Abdelaziz M, Lorite J, Muñoz-Pajares AJ, Valverde J. Evolution of pollination niches in a generalist plant clade. THE NEW PHYTOLOGIST 2015; 205:440-53. [PMID: 25252267 DOI: 10.1111/nph.13016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 07/29/2014] [Indexed: 05/27/2023]
Abstract
It is widely assumed that floral diversification occurs by adaptive shifts between pollination niches. In contrast to specialized flowers, identifying pollination niches of generalist flowers is a challenge. Consequently, how generalist pollination niches evolve is largely unknown. We apply tools from network theory and comparative methods to investigate the evolution of pollination niches among generalist species belonging to the genus Erysimum. These species have similar flowers. We found that the studied species may be grouped in several multidimensional niches separated not by a shift of pollinators, but instead by quantitative variation in the relative abundance of pollinator functional groups. These pollination niches did not vary in generalization degree; we did not find any evolutionary trend toward specialization within the studied clade. Furthermore, the evolution of pollination niche fitted to a Brownian motion model without phylogenetic signal, and was characterized by frequent events of niche convergences and divergences. We presume that the evolution of Erysimum pollination niches has occurred mostly by recurrent shifts between slightly different generalized pollinator assemblages varying spatially as a mosaic and without any change in specialization degree. Most changes in pollination niches do not prompt floral divergence, a reason why adaptation to pollinators is uncommon in generalist plants.
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Affiliation(s)
- José María Gómez
- Dpto de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Aridas (EEZA-CSIC), E-04120, Almería, Spain; Dpto de Ecología, Universidad de Granada, E-18071, Granada, Spain
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70
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Wellborn GA, Langerhans RB. Ecological opportunity and the adaptive diversification of lineages. Ecol Evol 2015; 5:176-95. [PMID: 25628875 PMCID: PMC4298445 DOI: 10.1002/ece3.1347] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 10/30/2014] [Accepted: 11/07/2014] [Indexed: 11/16/2022] Open
Abstract
The tenet that ecological opportunity drives adaptive diversification has been central to theories of speciation since Darwin, yet no widely accepted definition or mechanistic framework for the concept currently exists. We propose a definition for ecological opportunity that provides an explicit mechanism for its action. In our formulation, ecological opportunity refers to environmental conditions that both permit the persistence of a lineage within a community, as well as generate divergent natural selection within that lineage. Thus, ecological opportunity arises from two fundamental elements: (1) niche availability, the ability of a population with a phenotype previously absent from a community to persist within that community and (2) niche discordance, the diversifying selection generated by the adaptive mismatch between a population's niche-related traits and the newly encountered ecological conditions. Evolutionary response to ecological opportunity is primarily governed by (1) spatiotemporal structure of ecological opportunity, which influences dynamics of selection and development of reproductive isolation and (2) diversification potential, the biological properties of a lineage that determine its capacity to diversify. Diversification under ecological opportunity proceeds as an increase in niche breadth, development of intraspecific ecotypes, speciation, and additional cycles of diversification that may themselves be triggered by speciation. Extensive ecological opportunity may exist in depauperate communities, but it is unclear whether ecological opportunity abates in species-rich communities. Because ecological opportunity should generally increase during times of rapid and multifarious environmental change, human activities may currently be generating elevated ecological opportunity - but so far little work has directly addressed this topic. Our framework highlights the need for greater synthesis of community ecology and evolutionary biology, unifying the four major components of the concept of ecological opportunity.
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Affiliation(s)
- Gary A Wellborn
- Department of Biology, University of OklahomaNorman, Oklahoma, 73019
| | - R Brian Langerhans
- Department of Biological Sciences and W.M. Keck Center for Behavioral Biology, North Carolina State UniversityCampus Box 7617, Raleigh, North Carolina, 27695
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71
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Baldwin BG. Origins of Plant Diversity in the California Floristic Province. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2014. [DOI: 10.1146/annurev-ecolsys-110512-135847] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent biogeographic and evolutionary studies have led to improved understanding of the origins of exceptionally high plant diversity in the California Floristic Province (CA-FP). Spatial analyses of Californian plant diversity and endemism reinforce the importance of geographically isolated areas of high topographic and edaphic complexity as floristic hot spots, in which the relative influence of factors promoting evolutionary divergence and buffering of lineages against extinction has gained increased attention. Molecular phylogenetic studies spanning the flora indicate that immediate sources of CA-FP lineages bearing endemic species diversity have been mostly within North America—especially within the west and southwest—even for groups of north temperate affinity, and that most diversification of extant lineages in the CA-FP has occurred since the mid-Miocene, with the transition toward summer-drying. Process-focused studies continue to implicate environmental heterogeneity at local or broad geographic scales in evolutionary divergence within the CA-FP, often associated with reproductive or life-history shifts or sometimes hybridization.
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Affiliation(s)
- Bruce G. Baldwin
- Jepson Herbarium and Department of Integrative Biology, University of California, Berkeley, California 94720-2465
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72
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Haller BC, de Vos JM, Keller B, Hendry AP, Conti E. A tale of two morphs: modeling pollen transfer, magic traits, and reproductive isolation in parapatry. PLoS One 2014; 9:e106512. [PMID: 25211280 PMCID: PMC4161326 DOI: 10.1371/journal.pone.0106512] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/14/2014] [Indexed: 12/25/2022] Open
Abstract
The evolution of the flower is commonly thought to have spurred angiosperm diversification. Similarly, particular floral traits might have promoted diversification within specific angiosperm clades. We hypothesize that traits promoting the precise positional transfer of pollen between flowers might promote diversification. In particular, precise pollen transfer might produce partial reproductive isolation that facilitates adaptive divergence between parapatric populations differing in their reproductive-organ positions. We investigate this hypothesis with an individual-based model of pollen transfer dynamics associated with heterostyly, a floral syndrome that depends on precise pollen transfer. Our model shows that precise pollen transfer can cause sexual selection leading to divergence in reproductive-organ positions between populations served by different pollinators, pleiotropically causing an increase in reproductive isolation through a "magic trait" mechanism. Furthermore, this increased reproductive isolation facilitates adaptive divergence between the populations in an unlinked, ecologically selected trait. In a different pollination scenario, however, precise pollen transfer causes a decrease in adaptive divergence by promoting asymmetric gene flow. Our results highlight the idea that magic traits are not "magic" in isolation; in particular, the effect size of magic traits in speciation depends on the external environment, and also on other traits that modify the strength of the magic trait's influence on non-random mating. Overall, we show that the evolutionary consequences of pollen transfer dynamics can depend strongly on the available pollinator fauna and on the morphological fit between flowers and pollinators. Furthermore, our results illustrate the potential importance of even weak reproductive isolating barriers in facilitating adaptive divergence.
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Affiliation(s)
- Benjamin C. Haller
- Redpath Museum and Deptartment of Biology, McGill University, Montréal, Québec, Canada
- * E-mail:
| | - Jurriaan M. de Vos
- Deptartment of Ecology and Evol. Biol., Brown University, Providence, Rhode Island, United States of America
- Institute of Systematic Botany, University of Zürich, Zürich, Switzerland
| | - Barbara Keller
- Institute of Systematic Botany, University of Zürich, Zürich, Switzerland
| | - Andrew P. Hendry
- Redpath Museum and Deptartment of Biology, McGill University, Montréal, Québec, Canada
| | - Elena Conti
- Institute of Systematic Botany, University of Zürich, Zürich, Switzerland
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73
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Hudson EJ, Price TD. Pervasive Reinforcement and the Role of Sexual Selection in Biological Speciation. J Hered 2014; 105 Suppl 1:821-33. [DOI: 10.1093/jhered/esu041] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Coevolution, reciprocal adaptation between two or more taxa, is commonly invoked as a primary mechanism responsible for generating much of Earth's biodiversity. This conceptually appealing hypothesis is incredibly broad in evolutionary scope, encompassing diverse patterns and processes operating over timescales ranging from microbial generations to geological eras. However, we have surprisingly little evidence that large-scale associations between coevolution and diversity reflect a causal relationship at smaller timescales, in which coevolutionary selection is directly responsible for the formation of new species. In this synthesis, we critically evaluate evidence for the often-invoked hypothesis that coevolution is an important process promoting biological diversification. We conclude that the lack of widespread evidence for coevolutionary diversification may be best explained by the fact that coevolution's importance in diversification varies depending on the type of interaction and the scale of the diversification under consideration.
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Affiliation(s)
- David H Hembry
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California 94720
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Gamisch A, Fischer GA, Comes HP. Recurrent polymorphic mating type variation in Madagascan Bulbophyllum species (Orchidaceae) exemplifies a high incidence of auto-pollination in tropical orchids. BOTANICAL JOURNAL OF THE LINNEAN SOCIETY. LINNEAN SOCIETY OF LONDON 2014; 175:242-258. [PMID: 25821245 PMCID: PMC4373168 DOI: 10.1111/boj.12168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/11/2013] [Accepted: 03/24/2014] [Indexed: 05/13/2023]
Abstract
The transition from outcrossing to self-fertilization is one of the most common evolutionary changes in angiosperms. The orchid family exemplifies this evolutionary trend but, because of a general lack of large-scale surveys on auto-pollination in orchid taxa, the incidence and modes of auto-pollination among (sub)tropical orchids remain poorly known. In the present study, we assessed the frequency and mode of auto-pollination within and among species of a largely monophyletic group of Madagascan Bulbophyllum. The capacity for autonomous fruit set was investigated by bagging experiments in the greenhouse and the field, complemented with detailed floral micromorphological studies of the gynostemium. Our survey comprises 393 accessions, representing at least 78 species, and thus approximately 37% of the species diversity of the genus in the Madagascan region. Our studies revealed that mating type is directly related to gynostemium structure, most often involving the presence or absence of a physical barrier termed 'rostellum'. As a novel and unexpected finding, we identified eight species of a single lineage of Madagascan Bulbophyllum (termed 'clade C'), in which auto-pollinating morphs (selfers), either lacking a rostellum or (rarely) possessing a stigmatic rostellum, co-exist with their pollinator-dependent conspecifics (outcrossers). We hypothesize that auto-pollination via rostellum abortion has a simple genetic basis, and probably evolved rapidly and recurrently by subtle changes in the timing of rostellum development (heterochrony). Thus, species of clade C may have an intrinsic genetic and developmental lability toward auto-pollination, allowing rapid evolutionary response under environmental, perhaps human-disturbed conditions favouring reproductive assurance. Overall, these findings should stimulate further research on the incidence, evolution, and maintenance of mating type variation in tropical orchids, as well as how they adapt(ed) to changing environmental conditions.
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Affiliation(s)
- Alexander Gamisch
- Department of Organismic Biology, University of SalzburgA-5020, Salzburg, Austria
- *Corresponding author. E-mail:
| | - Gunter A Fischer
- Kadoorie Farm and Botanic Garden CorporationLam Kam Road, Tai Po, N.T., Hong Kong SAR
| | - Hans Peter Comes
- Department of Organismic Biology, University of SalzburgA-5020, Salzburg, Austria
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de Vos JM, Hughes CE, Schneeweiss GM, Moore BR, Conti E. Heterostyly accelerates diversification via reduced extinction in primroses. Proc Biol Sci 2014; 281:20140075. [PMID: 24759859 DOI: 10.1098/rspb.2014.0075] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The exceptional species diversity of flowering plants, exceeding that of their sister group more than 250-fold, is especially evident in floral innovations, interactions with pollinators and sexual systems. Multiple theories, emphasizing flower-pollinator interactions, genetic effects of mating systems or high evolvability, predict that floral evolution profoundly affects angiosperm diversification. However, consequences for speciation and extinction dynamics remain poorly understood. Here, we investigate trajectories of species diversification focusing on heterostyly, a remarkable floral syndrome where outcrossing is enforced via cross-compatible floral morphs differing in placement of their respective sexual organs. Heterostyly evolved at least 20 times independently in angiosperms. Using Darwin's model for heterostyly, the primrose family, we show that heterostyly accelerates species diversification via decreasing extinction rates rather than increasing speciation rates, probably owing to avoidance of the negative genetic effects of selfing. However, impact of heterostyly appears to differ over short and long evolutionary time-scales: the accelerating effect of heterostyly on lineage diversification is manifest only over long evolutionary time-scales, whereas recent losses of heterostyly may prompt ephemeral bursts of speciation. Our results suggest that temporal or clade-specific conditions may ultimately determine the net effects of specific traits on patterns of species diversification.
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Affiliation(s)
- Jurriaan M de Vos
- Institute of Systematic Botany, University of Zürich, , Zollikerstrasse 107, 8008 Zürich, Switzerland, Department of Ecology and Evolutionary Biology, Brown University, , 80 Waterman Street, Box G-W, Providence, RI 02912, USA, Department of Botany and Biodiversity Research, University of Vienna, , Rennweg 14, Vienna 1030, Austria, Department of Evolution and Ecology, University of California, , Davis, 1 Shields Avenue, CA 95616, USA
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77
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Armbruster WS. Floral specialization and angiosperm diversity: phenotypic divergence, fitness trade-offs and realized pollination accuracy. AOB PLANTS 2014; 6:plu003. [PMID: 24790124 PMCID: PMC4038416 DOI: 10.1093/aobpla/plu003] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/05/2014] [Indexed: 05/08/2023]
Abstract
Plant reproduction by means of flowers has long been thought to promote the success and diversification of angiosperms. It remains unclear, however, how this success has come about. Do flowers, and their capacity to have specialized functions, increase speciation rates or decrease extinction rates? Is floral specialization fundamental or incidental to the diversification? Some studies suggest that the conclusions we draw about the role of flowers in the diversification and increased phenotypic disparity (phenotypic diversity) of angiosperms depends on the system. For orchids, for example, specialized pollination may have increased speciation rates, in part because in most orchids pollen is packed in discrete units so that pollination is precise enough to contribute to reproductive isolation. In most plants, however, granular pollen results in low realized pollination precision, and thus key innovations involving flowers more likely reflect reduced extinction rates combined with opportunities for evolution of greater phenotypic disparity (phenotypic diversity) and occupation of new niches. Understanding the causes and consequences of the evolution of specialized flowers requires knowledge of both the selective regimes and the potential fitness trade-offs in using more than one pollinator functional group. The study of floral function and flowering-plant diversification remains a vibrant evolutionary field. Application of new methods, from measuring natural selection to estimating speciation rates, holds much promise for improving our understanding of the relationship between floral specialization and evolutionary success.
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Affiliation(s)
- W. Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
- Department of Biology, Norwegian University of Science & Technology, Trondheim N-7491, Norway
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Gómez JM, Muñoz-Pajares AJ, Abdelaziz M, Lorite J, Perfectti F. Evolution of pollination niches and floral divergence in the generalist plant Erysimum mediohispanicum. ANNALS OF BOTANY 2014; 113:237-49. [PMID: 23965614 PMCID: PMC3890381 DOI: 10.1093/aob/mct186] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 06/21/2013] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS How generalist plants diverge in response to pollinator selection without becoming specialized is still unknown. This study explores this question, focusing on the evolution of the pollination system in the pollination generalist Erysimum mediohispanicum (Brassicaceae). METHODS Pollinator assemblages were surveyed from 2001 to 2010 in 48 geo-referenced populations covering the entire geographic distribution of E. mediohispanicum. Bipartite modularity, a complex network tool, was used to find the pollination niche of each population. Evolution of the pollination niches and the correlated evolution of floral traits and pollination niches were explored using within-species comparative analyses. KEY RESULTS Despite being generalists, the E. mediohispanicum populations studied can be classified into five pollination niches. The boundaries between niches were not sharp, the niches differing among them in the relative frequencies of the floral visitor functional groups. The absence of spatial autocorrelation and phylogenetic signal indicates that the niches were distributed in a phylogeographic mosaic. The ancestral E. mediohispanicum populations presumably belonged to the niche defined by a high number of beetle and ant visits. A correlated evolution was found between pollination niches and some floral traits, suggesting the existence of generalist pollination ecotypes. CONCLUSIONS It is conjectured that the geographic variation in pollination niches has contributed to the observed floral divergence in E. mediohispanicum. The process mediating this floral divergence presumably has been adaptive wandering, but the adaptation to the local pollinator faunas has been not universal. The outcome is a landscape where a few populations locally adapted to their pollination environment (generalist pollination ecotypes) coexist with many populations where this local adaptation has failed and where the plant phenotype is not primarily shaped by pollinators.
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Affiliation(s)
| | | | | | - J. Lorite
- Departamento de Botánica, Universidad de Granada, E-18071 Granada, Spain
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79
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Armbruster WS, Shi XQ, Huang SQ. Do specialized flowers promote reproductive isolation? Realized pollination accuracy of three sympatric Pedicularis species. ANNALS OF BOTANY 2014; 113:331-40. [PMID: 24047714 PMCID: PMC3890382 DOI: 10.1093/aob/mct187] [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: 05/08/2023]
Abstract
BACKGROUND AND AIMS Interest in pollinator-mediated evolutionary divergence of flower phenotype and speciation in plants has been at the core of plant evolutionary studies since Darwin. Specialized pollination is predicted to lead to reproductive isolation and promote speciation among sympatric species by promoting partitioning of (1) the species of pollinators used, (2) when pollinators are used, or (3) the sites of pollen placement. Here this last mechanism is investigated by observing the pollination accuracy of sympatric Pedicularis species (Orobanchacae). METHODS Pollinator behaviour was observed on three species of Pedicularis (P. densispica, P. tricolor and P. dichotoma) in the Hengduan Mountains, south-west China. Using fluorescent powder and dyed pollen, the accuracy was assessed of stigma contact with, and pollen deposition on, pollinating bumble-bees, respectively. KEY RESULTS All three species of Pedicularis were pollinated by bumble-bees. It was found that the adaptive accuracy of female function was much higher than that of male function in all three flower species. Although peak pollen deposition corresponded to the optimal location on the pollinator (i.e. the site of stigma contact) for each species, substantial amounts of pollen were scattered over much of the bees' bodies. CONCLUSIONS The Pedicularis species studied in the eastern Himalayan region did not conform with Grant's 'Pedicularis Model' of mechanical reproductive isolation. The specialized flowers of this diverse group of plants seem unlikely to have increased the potential for reproductive isolation or influenced rates of speciation. It is suggested instead that the extreme species richness of the Pedicularis clade was generated in other ways and that specialized flowers and substantial pollination accuracy evolved as a response to selection generated by the diversity of co-occurring congeners.
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Affiliation(s)
- W. Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
- Department of Biology, NTNU, NO-7491 Trondheim, Norway
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
- For correspondence. E-mail
| | - Xiao-Qing Shi
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shuang-Quan Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Van der Niet T, Peakall R, Johnson SD. Pollinator-driven ecological speciation in plants: new evidence and future perspectives. ANNALS OF BOTANY 2014; 113:199-211. [PMID: 24418954 PMCID: PMC3890394 DOI: 10.1093/aob/mct290] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 11/17/2013] [Indexed: 05/07/2023]
Abstract
BACKGROUND The hypothesis that pollinators have been important drivers of angiosperm diversity dates back to Darwin, and remains an important research topic today. Mounting evidence indicates that pollinators have the potential to drive diversification at several different stages of the evolutionary process. Microevolutionary studies have provided evidence for pollinator-mediated floral adaptation, while macroevolutionary evidence supports a general pattern of pollinator-driven diversification of angiosperms. However, the overarching issue of whether, and how, shifts in pollination system drive plant speciation represents a critical gap in knowledge. Bridging this gap is crucial to fully understand whether pollinator-driven microevolution accounts for the observed macroevolutionary patterns. Testable predictions about pollinator-driven speciation can be derived from the theory of ecological speciation, according to which adaptation (microevolution) and speciation (macroevolution) are directly linked. This theory is a particularly suitable framework for evaluating evidence for the processes underlying shifts in pollination systems and their potential consequences for the evolution of reproductive isolation and speciation. SCOPE This Viewpoint paper focuses on evidence for the four components of ecological speciation in the context of plant-pollinator interactions, namely (1) the role of pollinators as selective agents, (2) floral trait divergence, including the evolution of 'pollination ecotypes', (3) the geographical context of selection on floral traits, and (4) the role of pollinators in the evolution of reproductive isolation. This Viewpoint also serves as the introduction to a Special Issue on Pollinator-Driven Speciation in Plants. The 13 papers in this Special Issue range from microevolutionary studies of ecotypes to macroevolutionary studies of historical ecological shifts, and span a wide range of geographical areas and plant families. These studies further illustrate innovative experimental approaches, and they employ modern tools in genetics and floral trait quantification. Future advances to the field require better quantification of selection through male fitness and pollinator isolation, for instance by exploiting next-generation sequencing technologies. By combining these new tools with strategically chosen study systems, and smart experimental design, we predict that examples of pollinator-driven speciation will be among the most widespread and compelling of all cases of ecological speciation.
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Affiliation(s)
- Timotheüs Van der Niet
- Naturalis Biodiversity Center, P.O. Box 9514, 2300 RA, Leiden, The Netherlands
- Leiden University, Section Botany, P.O. Box 9514, 2300 RA, Leiden, The Netherlands
- School of Life Sciences, University of KwaZulu Natal, P/Bag X01, Scottsville 3209, Pietermaritzburg, South Africa
| | - Rod Peakall
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Steven D. Johnson
- School of Life Sciences, University of KwaZulu Natal, P/Bag X01, Scottsville 3209, Pietermaritzburg, South Africa
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81
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Fernández-Mazuecos M, Blanco-Pastor JL, Gómez JM, Vargas P. Corolla morphology influences diversification rates in bifid toadflaxes (Linaria sect. Versicolores). ANNALS OF BOTANY 2013; 112:1705-22. [PMID: 24142920 PMCID: PMC3838546 DOI: 10.1093/aob/mct214] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS The role of flower specialization in plant speciation and evolution remains controversial. In this study the evolution of flower traits restricting access to pollinators was analysed in the bifid toadflaxes (Linaria sect. Versicolores), a monophyletic group of ~30 species and subspecies with highly specialized corollas. METHODS A time-calibrated phylogeny based on both nuclear and plastid DNA sequences was obtained using a coalescent-based method, and flower morphology was characterized by means of morphometric analyses. Directional trends in flower shape evolution and trait-dependent diversification rates were jointly analysed using recently developed methods, and morphological shifts were reconstructed along the phylogeny. Pollinator surveys were conducted for a representative sample of species. KEY RESULTS A restrictive character state (narrow corolla tube) was reconstructed in the most recent common ancestor of Linaria sect. Versicolores. After its early loss in the most species-rich clade, this character state has been convergently reacquired in multiple lineages of this clade in recent times, yet it seems to have exerted a negative influence on diversification rates. Comparative analyses and pollinator surveys suggest that the narrow- and broad-tubed flowers are evolutionary optima representing divergent strategies of pollen placement on nectar-feeding insects. CONCLUSIONS The results confirm that different forms of floral specialization can lead to dissimilar evolutionary success in terms of diversification. It is additionally suggested that opposing individual-level and species-level selection pressures may have driven the evolution of pollinator-restrictive traits in bifid toadflaxes.
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Affiliation(s)
- Mario Fernández-Mazuecos
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
- For correspondence. E-mail
| | - José Luis Blanco-Pastor
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
| | - José M. Gómez
- Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas (EEZA-CSIC), Ctra. Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain
- Departamento de Ecología, Universidad de Granada, Avenida de Fuente Nueva s/n, 18071 Granada, Spain
| | - Pablo Vargas
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
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82
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Huang SQ, Shi XQ. Floral isolation in Pedicularis: how do congeners with shared pollinators minimize reproductive interference? THE NEW PHYTOLOGIST 2013; 199:858-65. [PMID: 23672259 DOI: 10.1111/nph.12327] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/14/2013] [Indexed: 05/23/2023]
Abstract
To minimize interspecific pollination, it has been suggested that pollen is placed on different parts of a pollinator's body corresponding to the conspecific location of pollen pickup by the stigma. Although Pedicularis is regarded as a classic example of pollinator-mediated floral isolation, such reciprocal pollen placement has not been demonstrated experimentally. This leads us to question previous observations of pollen release in Pedicularis species. Here, we show that pollen grains are released from the tip, rather than the basal opening, of the galea (the hoodlike upper lip of the corolla) in eight nectarless Pedicularis species, mimicking pollen release from poricidal anthers. We used safranin-stained pollen within anthers to track pollen placement in three Pedicularis species, and showed that pollen was deposited on numerous parts of the bumblebee's body. However, fluorescent powder placed on the stigmas to detect the contact location on the bumblebee's body was deposited mainly on the major position of pollen placement in each of the three species. Such segregation of pollen placement and pickup between species sharing the same pollinator probably helps to reduce reproductive interference, but the positions of pollen placement and stigma contact on the bumblebee's body were not as precise as previously thought.
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Affiliation(s)
- Shuang-Quan Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China.
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83
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Yoder JB, Smith CI, Rowley DJ, Flatz R, Godsoe W, Drummond C, Pellmyr O. Effects of gene flow on phenotype matching between two varieties of Joshua tree (Yucca brevifolia
; Agavaceae) and their pollinators. J Evol Biol 2013; 26:1220-33. [DOI: 10.1111/jeb.12134] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 01/12/2013] [Accepted: 01/14/2013] [Indexed: 11/29/2022]
Affiliation(s)
- J. B. Yoder
- Department of Plant Biology; University of Minnesota; Saint Paul MN USA
| | - C. I. Smith
- Department of Biology; Willamette University; Salem OR USA
| | - D. J. Rowley
- Department of Biological Sciences; University of Idaho; Moscow ID USA
| | - R. Flatz
- Department of Biology; Willamette University; Salem OR USA
| | - W. Godsoe
- School of Biological Sciences; University of Canterbury; Christchurch New Zealand
| | - C. Drummond
- Department of Biological Sciences; University of Idaho; Moscow ID USA
| | - O. Pellmyr
- Department of Biological Sciences; University of Idaho; Moscow ID USA
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84
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Van Rossum F, Vereecken NJ, Brédat E, Michez D. Pollen dispersal and fruit production in Vaccinium oxycoccos and comparison with its sympatric congener V. uliginosum. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:344-352. [PMID: 22823148 DOI: 10.1111/j.1438-8677.2012.00646.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Investigating plant-pollinator interactions and pollen dispersal are particularly relevant for understanding processes ensuring long-term viability of fragmented plant populations. Pollen dispersal patterns may vary strongly, even between similar congeneric species, depending on the mating system, pollinator assemblages and floral traits. We investigated pollen dispersal and fruit production in a population of Vaccinium oxycoccos, an insect-pollinated shrub, and compared the pollen dispersal pattern with a co-flowering, sympatric congener, V. uliginosum. We examined whether they share pollinators (through interspecific fluorescent dye transfers) and may differently attract pollinators, by comparing their floral colour as perceived by insects. Fluorescent dyes were mainly dispersed over short distances (80% within 40.4 m (max. 94.5 m) for V. oxycoccos and 3.0 m (max. 141.3 m) for V. uliginosum). Dye dispersal in V. oxycoccos was not significantly affected by plant area, floral display or the proximity to V. uliginosum plants. Interspecific dye transfers were observed, indicating pollinator sharing. The significantly lower dye deposition on V. oxycoccos stigmas suggests lower visitation rates by pollinators, despite higher flower density and local abundance. The spectral reflectance analysis indicates that bees are unlikely to be able to discriminate between the two species based on floral colour alone. Fruit production increased with increasing floral display, but was not affected by proximity to V. uliginosum plants. Our study highlights that fragmented populations of V. oxycoccos, when sympatric with co-flowering V. uliginosum, might incur increased competition for the shared pollinators in the case of pollination disruption, which might then reduce outcrossed seed set.
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Affiliation(s)
- F Van Rossum
- Department of Vascular Plants, National Botanic Garden of Belgium, Domein van Bouchout, Meise, Belgium.
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85
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Abstract
A major goal of evolutionary biology is to understand how diverging populations become species. The evolution of reproductive isolation (RI) halts the genomic homogenization caused by gene flow and recombination, and enables differentiation and local adaptations to become fixed between newly forming species. Selection can favor the strengthening of RI through a process termed reinforcement. Reinforcement occurs when selection favors traits that decrease mating between two incipient species in response to costly mating or the production of maladapted hybrids. Although this process has been investigated more frequently in animals, there is also evidence of reinforcement in plants. There are three strategies for the investigation of the process of reinforcement: case studies of species or diverging taxa; experimental evolution studies; and comparative studies. Here, I discuss how all three strategies find evidence consistent with reinforcement occurring in plants. I focus largely on case studies, and use research on Phlox drummondii to illustrate the importance of testing alternative hypotheses. Although the existing evidence suggests that reinforcement can occur, further investigations, particularly using large-scale comparative studies, are needed to determine the importance of reinforcement in plant speciation.
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Affiliation(s)
- Robin Hopkins
- The University of Texas at Austin, 1 University Station, Austin, TX 78712, USA.
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86
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Starr TN, Gadek KE, Yoder JB, Flatz R, Smith CI. Asymmetric hybridization and gene flow between Joshua trees (Agavaceae:Yucca) reflect differences in pollinator host specificity. Mol Ecol 2012. [DOI: 10.1111/mec.12124] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tyler N. Starr
- Department of Biology; Willamette University; 900 State Street Salem OR 97301 USA
| | - Katherine E. Gadek
- Department of Biology; Willamette University; 900 State Street Salem OR 97301 USA
| | - Jeremy B. Yoder
- Department of Biological Sciences; University of Idaho; Moscow ID 83844 USA
| | - Ramona Flatz
- Department of Biology; Willamette University; 900 State Street Salem OR 97301 USA
| | - Christopher I. Smith
- Department of Biology; Willamette University; 900 State Street Salem OR 97301 USA
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87
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Hufford KM, Krauss SL, Veneklaas EJ. Inbreeding and outbreeding depression in Stylidium hispidum: implications for mixing seed sources for ecological restoration. Ecol Evol 2012; 2:2262-73. [PMID: 23139884 PMCID: PMC3488676 DOI: 10.1002/ece3.302] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 05/21/2012] [Accepted: 05/23/2012] [Indexed: 11/28/2022] Open
Abstract
The benefits of composite rather than local seed provenances for ecological restoration have recently been argued, largely on the basis of maximizing evolutionary potential. However, these arguments have downplayed the potentially negative consequences of outbreeding depression once mixed provenances interbreed. In this study, we compared intraspecific F1 hybrid performance and molecular marker differentiation among four populations of Stylidium hispidum, a species endemic to Southwestern Australia. Multivariate ordination of 134 AFLP markers analyzed genetic structure and detected two clusters of paired sites that diverged significantly for marker variation along a latitudinal boundary. To test for outbreeding depression and to determine the consequences of molecular population divergence for hybrid fitness, we conducted controlled pollinations and studied germination and survival for three cross categories (within-population crosses, short- and long-distance F1 hybrids) for paired sites distributed within and between the two genetically differentiated regions. We found evidence of outbreeding depression in long-distance hybrids (111–124 km), and inbreeding depression among progeny of within-population crosses, relative to short-distance (3–10 km) hybrids, suggesting an intermediate optimal outcrossing distance in this species. These results are discussed in light of the evolutionary consequences of mixing seed sources for biodiversity restoration.
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Affiliation(s)
- Kristina M Hufford
- Kings Park and Botanic Garden, Botanic Gardens and Parks Authority Western Australia, Australia ; School of Plant Biology, The University of Western Australia Western Australia, Australia ; Department of Ecosystem Science and Management, University of Wyoming Laramie, Wyoming
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88
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Emery NC, Forrestel EJ, Jui G, Park MS, Baldwin BG, Ackerly DD. Niche evolution across spatial scales: climate and habitat specialization in CaliforniaLasthenia(Asteraceae). Ecology 2012. [DOI: 10.1890/11-0504.1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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89
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Eaton DAR, Fenster CB, Hereford J, Huang SQ, Ree RH. Floral diversity and community structure inPedicularis(Orobanchaceae). Ecology 2012. [DOI: 10.1890/11-0501.1] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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90
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Weber MG, Agrawal AA. Phylogeny, ecology, and the coupling of comparative and experimental approaches. Trends Ecol Evol 2012; 27:394-403. [DOI: 10.1016/j.tree.2012.04.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 04/20/2012] [Accepted: 04/23/2012] [Indexed: 11/27/2022]
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91
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van der Niet T, Johnson SD. Phylogenetic evidence for pollinator-driven diversification of angiosperms. Trends Ecol Evol 2012; 27:353-61. [PMID: 22445687 DOI: 10.1016/j.tree.2012.02.002] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 02/07/2012] [Accepted: 02/14/2012] [Indexed: 01/07/2023]
Affiliation(s)
- Timotheüs van der Niet
- School of Life Sciences, University of KwaZulu-Natal, P. Bag X01, Scottsville 3209, South Africa.
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92
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Muchhala N, Thomson JD. Interspecific competition in pollination systems: costs to male fitness via pollen misplacement. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2011.01950.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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93
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Livshultz T, Mead JV, Goyder DJ, Brannin M. Climate niches of milkweeds with plesiomorphic traits (Secamonoideae; Apocynaceae) and the milkweed sister group link ancient African climates and floral evolution. AMERICAN JOURNAL OF BOTANY 2011; 98:1966-1977. [PMID: 22074778 DOI: 10.3732/ajb.1100202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY Climate change that increases mortality of plants and pollinators can create mate-finding Allee effects and thus act as a strong selective force on floral morphology. Milkweeds (Secamonoideae and Asclepiadoideae; Apocynaceae) are typically small plants of seasonally dry habitats, with pollinia and high pollen-transfer efficiency. Their sister group (tribe Baisseeae and Dewevrella) is mostly comprised of giant lianas of African rainforests, with pollen in monads. Comparison of the two groups motivated a new hypothesis: milkweeds evolved in the context of African aridification and the shifting of rainforest to dry forest. Pollinia and high pollen-transfer efficiency may have been adaptations that alleviated mate-finding Allee effects generated by high mortality during droughts. We formally tested whether milkweeds have a drier climate niche by comparing milkweeds with plesiomorphic traits (Secamonoideae) and the milkweed sister group in continental Africa. METHODS We georeferenced specimens of the milkweed sister group and Secamonoideae in continental Africa, extracted 19 climatic variables from the Worldclim model, conducted factor analysis to identify correlated suites of variables, and compared the frequency distributions of the two lineages relative to each factor. KEY RESULTS The distributions of Secamonoideae and the milkweed sister group differed significantly relative to four factors, each correlated with a distinct suite of climate parameters: (1) air temperature (Secamonoideae: cooler), (2) total and (3) summer precipitation (Secamonoideae: drier), and (4) temperature seasonality and isothermality (Secamonoideae: more seasonal and less isothermal). CONCLUSIONS Secamonoideae in continental Africa inhabit drier, cooler sites than do the milkweed sister group, consistent with a shift from rainforests to dry forests in a cooling climate.
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Affiliation(s)
- Tatyana Livshultz
- The Academy of Natural Sciences of Drexel University, Philadelphia, Pennsylvania 19103, USA.
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94
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Smith CI, Tank S, Godsoe W, Levenick J, Strand E, Esque T, Pellmyr O. Comparative phylogeography of a coevolved community: concerted population expansions in Joshua trees and four yucca moths. PLoS One 2011; 6:e25628. [PMID: 22028785 PMCID: PMC3196504 DOI: 10.1371/journal.pone.0025628] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 09/08/2011] [Indexed: 01/26/2023] Open
Abstract
Comparative phylogeographic studies have had mixed success in identifying common phylogeographic patterns among co-distributed organisms. Whereas some have found broadly similar patterns across a diverse array of taxa, others have found that the histories of different species are more idiosyncratic than congruent. The variation in the results of comparative phylogeographic studies could indicate that the extent to which sympatrically-distributed organisms share common biogeographic histories varies depending on the strength and specificity of ecological interactions between them. To test this hypothesis, we examined demographic and phylogeographic patterns in a highly specialized, coevolved community--Joshua trees (Yucca brevifolia) and their associated yucca moths. This tightly-integrated, mutually interdependent community is known to have experienced significant range changes at the end of the last glacial period, so there is a strong a priori expectation that these organisms will show common signatures of demographic and distributional changes over time. Using a database of >5000 GPS records for Joshua trees, and multi-locus DNA sequence data from the Joshua tree and four species of yucca moth, we combined paleaodistribution modeling with coalescent-based analyses of demographic and phylgeographic history. We extensively evaluated the power of our methods to infer past population size and distributional changes by evaluating the effect of different inference procedures on our results, comparing our palaeodistribution models to Pleistocene-aged packrat midden records, and simulating DNA sequence data under a variety of alternative demographic histories. Together the results indicate that these organisms have shared a common history of population expansion, and that these expansions were broadly coincident in time. However, contrary to our expectations, none of our analyses indicated significant range or population size reductions at the end of the last glacial period, and the inferred demographic changes substantially predate Holocene climate changes.
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95
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Ayasse M, Stökl J, Francke W. Chemical ecology and pollinator-driven speciation in sexually deceptive orchids. PHYTOCHEMISTRY 2011; 72:1667-1677. [PMID: 21497864 DOI: 10.1016/j.phytochem.2011.03.023] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/23/2011] [Accepted: 03/24/2011] [Indexed: 05/30/2023]
Abstract
Sexually deceptive orchids mimic females of their pollinator species to attract male insects for pollination. Pollination by sexual deception has independently evolved in European, Australian, South African, and South American orchid taxa. Reproductive isolation is mainly based on pre-mating isolation barriers, the specific attraction of males of a single pollinator species, mostly bees, by mimicking the female species-specific sex-pheromone. However, in rare cases post-mating barriers have been found. Sexually deceptive orchids are ideal candidates for studies of sympatric speciation, because key adaptive traits such as the pollinator-attracting scent are associated with their reproductive success and with pre-mating isolation. During the last two decades several investigations studied processes of ecological speciation in sexually deceptive orchids of Europe and Australia. Using various methods like behavioural experiments, chemical, electrophysiological, and population-genetic analyses it was shown that minor changes in floral odour bouquets might be the driving force for pollinator shifts and speciation events. New pollinators act as an isolation barrier towards other sympatrically occurring species. Hybridization occurs because of similar odour bouquets of species and the overlap of flowering periods. Hybrid speciation can also lead to the displacement of species by the hybrid population, if its reproductive success is higher than that in the parental species.
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Affiliation(s)
- Manfred Ayasse
- Institute for Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany.
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96
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Zitari A, Scopece G, Helal AN, Widmer A, Cozzolino S. Is floral divergence sufficient to maintain species boundaries upon secondary contact in Mediterranean food-deceptive orchids? Heredity (Edinb) 2011; 108:219-28. [PMID: 21792224 DOI: 10.1038/hdy.2011.61] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Analyzing the processes that determine whether species boundaries are maintained on secondary contact may shed light on the early phase of speciation. In Anacamptis morio and Anacamptis longicornu, two Mediterranean orchid sister-species, we used molecular and morphological analyses, together with estimates of pollination success and experimental crosses, to assess whether floral isolation can shelter the species' genomes from genetic admixture on secondary contact. We found substantial genetic and morphological homogenization in sympatric populations in combination with an apparent lack of postmating isolation. We further detected asymmetric introgression in the sympatric populations and an imbalance in cytotype representation, which may be due either to a difference in flowering phenology or else be a consequence of cytonuclear incompatibilities. Estimates of genetic clines for markers across sympatric zones revealed markers that significantly deviated from neutral expectations. We observed a significant correlation between spur length and reproductive success in sympatric populations, which may suggest that directional selection is the main cause of morphological differentiation in this species pair. Our results suggest that allopatric divergence has not led to the evolution of sufficient reproductive isolation to prevent genomic admixture on secondary contact in this orchid species pair.
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Affiliation(s)
- A Zitari
- Department of Structural and Functional Biology, University Federico II of Naples, Naples, Italy
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97
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Nicotra AB, Leigh A, Boyce CK, Jones CS, Niklas KJ, Royer DL, Tsukaya H. The evolution and functional significance of leaf shape in the angiosperms. FUNCTIONAL PLANT BIOLOGY : FPB 2011; 38:535-552. [PMID: 32480907 DOI: 10.1071/fp11057] [Citation(s) in RCA: 209] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 05/30/2011] [Indexed: 05/18/2023]
Abstract
Angiosperm leaves manifest a remarkable diversity of shapes that range from developmental sequences within a shoot and within crown response to microenvironment to variation among species within and between communities and among orders or families. It is generally assumed that because photosynthetic leaves are critical to plant growth and survival, variation in their shape reflects natural selection operating on function. Several non-mutually exclusive theories have been proposed to explain leaf shape diversity. These include: thermoregulation of leaves especially in arid and hot environments, hydraulic constraints, patterns of leaf expansion in deciduous species, biomechanical constraints, adaptations to avoid herbivory, adaptations to optimise light interception and even that leaf shape variation is a response to selection on flower form. However, the relative importance, or likelihood, of each of these factors is unclear. Here we review the evolutionary context of leaf shape diversification, discuss the proximal mechanisms that generate the diversity in extant systems, and consider the evidence for each the above hypotheses in the context of the functional significance of leaf shape. The synthesis of these broad ranging areas helps to identify points of conceptual convergence for ongoing discussion and integrated directions for future research.
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Affiliation(s)
- Adrienne B Nicotra
- Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Andrea Leigh
- School of the Environment, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - C Kevin Boyce
- Department of the Geophysical Sciences, 5734 S. Ellis Avenue, Chicago, IL 60637, USA
| | - Cynthia S Jones
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Unit-3043, Storrs, CT 06269, USA
| | - Karl J Niklas
- Department of Plant Biology, Cornell University, 412 Mann Library Building, Cornell University, Ithaca, NY 14853, USA
| | - Dana L Royer
- Department of Earth and Environmental Sciences, Wesleyan University, 265 Church Street, Middletown, CT 06459, USA
| | - Hirokazu Tsukaya
- Graduate School of Science, University of Tokyo, Science Build #2, 7-3-1 Hongo, Tokyo 113-0033, Japan
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98
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Schnitzler J, Barraclough TG, Boatwright JS, Goldblatt P, Manning JC, Powell MP, Rebelo T, Savolainen V. Causes of Plant Diversification in the Cape Biodiversity Hotspot of South Africa. Syst Biol 2011; 60:343-57. [DOI: 10.1093/sysbio/syr006] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jan Schnitzler
- Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
| | - Timothy G. Barraclough
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
- Division of Biology and NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
| | - James S. Boatwright
- South African National Biodiversity Institute, Kirstenbosch, Private Bag X7, Claremont 7735, Cape Town, South Africa
- Department of Botany and Plant Biotechnology, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, South Africa
| | - Peter Goldblatt
- Missouri Botanical Garden, PO Box 299, St Louis, MO 63166-0299, USA
| | - John C. Manning
- South African National Biodiversity Institute, Kirstenbosch, Private Bag X7, Claremont 7735, Cape Town, South Africa
| | - Martyn P. Powell
- Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
| | - Tony Rebelo
- South African National Biodiversity Institute, Kirstenbosch, Private Bag X7, Claremont 7735, Cape Town, South Africa
| | - Vincent Savolainen
- Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
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ALCANTARA SUZANA, LOHMANN LÚCIAG. Contrasting phylogenetic signals and evolutionary rates in floral traits of Neotropical lianas. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2010.01567.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Muchhala N, Brown Z, Armbruster W, Potts M. Competition Drives Specialization in Pollination Systems through Costs to Male Fitness. Am Nat 2010; 176:732-43. [DOI: 10.1086/657049] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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