1
|
Gazaix A, Grillas P, Papuga G, Fontes H, Sabatier F, Pons V, Gauthier P, Thompson JD. Ecological niche differentiation among six annual Lythrum species in Mediterranean temporary pools. Oecologia 2021; 197:715-727. [PMID: 34716492 DOI: 10.1007/s00442-021-05067-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 10/18/2021] [Indexed: 12/01/2022]
Abstract
The ecological niche defines the favourable range of a species in a multidimensional space of ecological factors that determine the presence and function of individuals. This fundamental concept in ecology is widely used to understand plant species coexistence and segregation. In this study, we test for ecological differentiation among six annual Lythrum species that are characteristic of temporary pools in the South of France, where they either coexist or occur separately. We first analysed the co-occurrence of species at two different geographical scales: cluster analyses of species presence in 10 km grid cells and coexistence in 0.25 m2 quadrats within populations of each species. Second, for three to nine populations of each species, we quantified a range of biotic and abiotic parameters using point contacts and soil measurements in five 0.25 m2 quadrats per population. We performed PCA on all variables and analysed each variable separately to compare the ecological niche features of the six species. A phenological index was assessed for the plant community of each site. We detected highly localized niche differentiation in terms of soil pH (all species) and for a range of variables among pairs of species. The six species also showed marked differences in the flowering period relative to the mean and variability of flowering time in their local community. These fine-scaled niche differences are associated with phylogenetic distances among species and may contribute to species' coexistence. These results are integrated in a conservation management plan for the habitat of the rarest species in this group.
Collapse
Affiliation(s)
- Antoine Gazaix
- Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, Le Sambuc, 13200, Arles, France.
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.
| | - Patrick Grillas
- Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, Le Sambuc, 13200, Arles, France
| | - Guillaume Papuga
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- AMAP, IRD, CNRS, CIRAD, INRA, Univ Montpellier, Montpellier, France
| | - Hugo Fontes
- Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, Le Sambuc, 13200, Arles, France
| | - Florent Sabatier
- Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, Le Sambuc, 13200, Arles, France
| | - Virginie Pons
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | | | - John D Thompson
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| |
Collapse
|
2
|
Ye H, Wu J, Wang Z, Hou H, Gao Y, Han W, Ru W, Sun G, Wang Y. Population genetic variation characterization of the boreal tree Acer ginnala in Northern China. Sci Rep 2020; 10:13515. [PMID: 32782277 PMCID: PMC7419535 DOI: 10.1038/s41598-020-70444-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 07/24/2020] [Indexed: 11/09/2022] Open
Abstract
Genetic diversity and differentiation are revealed particularly through spatio-temporal environmental heterogeneity. Acer ginnala, as a deciduous shrub/small tree, is a foundation species in many terrestrial ecosystems of Northern China. Owing to its increased use as an economic resource, this species has been in the vulnerability. Therefore, the elucidations of the genetic differentiation and influence of environmental factors on A. ginnala are very critical for its management and future utilization strategies. In this study, high genetic diversity and differentiation occurred in A. ginnala, which might be resulted from its pollination mechanism and species characteristics. Compared with the species level, relatively low genetic diversity was detected at the population level that might be the cause for its vulnerability. There was no significant relationship between genetic and geographical distances, while a significant correlation existed between genetic and environmental distances. Among nineteen climate variables, Annual Mean Temperature (bio1), Mean Diurnal Range (bio2), Isothermality (bio3), Temperature Seasonality (bio4), Precipitation of Wettest Month (bio13), Precipitation Seasonality (bio15), and Precipitation of Warmest Quarter (bio18) could explain the substantial levels of genetic variation (> 40%) in this species. The A. ginnala populations were isolated into multi-subpopulations by the heterogeneous climate conditions, which subsequently promoted the genetic divergence. Climatic heterogeneity played an important role in the pattern of genetic differentiation and population distribution of A. ginnala across a relatively wide range in Northern China. These would provide some clues for the conservation and management of this vulnerable species.
Collapse
Affiliation(s)
- Hang Ye
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China
| | - Jiahui Wu
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China.,Changzhi University, Changzhi, 046011, Shanxi, China
| | - Zhi Wang
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China
| | - Huimin Hou
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China
| | - Yue Gao
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China
| | - Wei Han
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China
| | - Wenming Ru
- Changzhi University, Changzhi, 046011, Shanxi, China.
| | - Genlou Sun
- Department of Biology, Saint Mary's University, Halifax, NS, B3H3C3, Canada.
| | - Yiling Wang
- College of Life Science, Shanxi Normal University, Linfen, 041000, Shanxi, China.
| |
Collapse
|
3
|
Latron M, Arnaud JF, Ferla H, Godé C, Duputié A. Effects of contemporary shifts of range margins on patterns of genetic structure and mating system in two coastal plant species. Heredity (Edinb) 2020; 124:336-350. [PMID: 31541203 PMCID: PMC6972893 DOI: 10.1038/s41437-019-0269-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 11/08/2022] Open
Abstract
Species' geographical ranges are often restricted due to niche limitation resulting in geographical isolation and reduced population size at range margins. Under the "abundant center" paradigm, static marginal populations are thus expected to show higher genetic differentiation and lower genetic diversity than core populations. Low mate availability may also drive shifts toward higher propensity for selfing in geographically marginal populations. However, these predictions remain to be validated for contemporary range shifts occurring under current environmental change. This study is devoted to bridging this gap and assesses the spatial patterns of genetic structure and mating system across the geographical range of two coastal plant species characterized by contrasting contemporary range dynamics: the receding myrmecochorous Dune pansy (Viola tricolor subsp. curtisii) and the widespread expanding hydrochorous Rock samphire (Crithmum maritimum). Both species exhibited high propensity for selfing, with indications of inbreeding depression acting at early life stages. In Dune pansy, a biogeographical break was observed between core and marginal populations, with trailing-edge populations showing higher levels of genetic differentiation, reduced genetic diversity, and higher levels of selfing estimated through progeny arrays. In contrast, genetic structuring was weak in Rock samphire and no clear spatial trends were observed in genetic diversity nor in mating system, likely the result of efficient long-distance seed dispersal by sea-surface currents. Our study highlights that key species differences in life-history traits related to dispersal and/or mate limitation modify the expectations of genetic diversity loss and mating system shift in contemporary range-expanding populations, as compared with historical core populations.
Collapse
Affiliation(s)
- Mathilde Latron
- University of Lille, CNRS, UMR 8198-Evo-Eco-Paleo, F-59000, Lille, France
| | | | - Héloïse Ferla
- University of Lille, CNRS, UMR 8198-Evo-Eco-Paleo, F-59000, Lille, France
| | - Cécile Godé
- University of Lille, CNRS, UMR 8198-Evo-Eco-Paleo, F-59000, Lille, France
| | - Anne Duputié
- University of Lille, CNRS, UMR 8198-Evo-Eco-Paleo, F-59000, Lille, France.
| |
Collapse
|
4
|
André A, Millien V, Galan M, Ribas A, Michaux JR. Effects of parasite and historic driven selection on the diversity and structure of a MHC-II gene in a small mammal species (Peromyscus leucopus) undergoing range expansion. Evol Ecol 2017. [DOI: 10.1007/s10682-017-9898-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
5
|
Pironon S, Papuga G, Villellas J, Angert AL, García MB, Thompson JD. Geographic variation in genetic and demographic performance: new insights from an old biogeographical paradigm. Biol Rev Camb Philos Soc 2016; 92:1877-1909. [DOI: 10.1111/brv.12313] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 10/07/2016] [Accepted: 10/17/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Samuel Pironon
- Instituto Pirenaico de Ecología (IPE-CSIC); Box 1005 avenida Montañana 50059 Zaragoza, Spain
| | - Guillaume Papuga
- UMR 5175 Centre d'Ecologie Fonctionnelle et Evolutive, CNRS; Box 1019 route de Mende 34090 Montpellier France
- Dipartimento di Scienze della Natura e del Territorio; Università degli Studi di Sassari; Box 21 Piazza Universitá 07100 Sassari Italy
| | - Jesús Villellas
- Department of Biology; Duke University; Box 90338 Durham NC 27708-0338 U.S.A
| | - Amy L. Angert
- Departments of Botany and Zoology; University of British Columbia; Box 4200-6270 University Boulevard, Vancouver V6T 1Z4 Canada
| | - María B. García
- Instituto Pirenaico de Ecología (IPE-CSIC); Box 1005 avenida Montañana 50059 Zaragoza, Spain
| | - John D. Thompson
- UMR 5175 Centre d'Ecologie Fonctionnelle et Evolutive, CNRS; Box 1019 route de Mende 34090 Montpellier France
| |
Collapse
|
6
|
Szczecińska M, Sramko G, Wołosz K, Sawicki J. Genetic Diversity and Population Structure of the Rare and Endangered Plant Species Pulsatilla patens (L.) Mill in East Central Europe. PLoS One 2016; 11:e0151730. [PMID: 27003296 PMCID: PMC4803199 DOI: 10.1371/journal.pone.0151730] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 03/03/2016] [Indexed: 11/25/2022] Open
Abstract
Pulsatilla patens s.s. is a one of the most endangered plant species in Europe. The present range of this species in Europe is highly fragmented and the size of the populations has been dramatically reduced in the past 50 years. The rapid disappearance of P. patens localities in Europe has prompted the European Commission to initiate active protection of this critically endangered species. The aim of this study was to estimate the degree and distribution of genetic diversity within European populations of this endangered species. We screened 29 populations of P. patens using a set of six microsatellite primers. The results of our study indicate that the analyzed populations are characterized by low levels of genetic diversity (Ho = 0.005) and very high levels of inbreeding (FIS = 0.90). These results suggest that genetic erosion could be partially responsible for the lower fitness in smaller populations of this species. Private allelic richness was very low, being as low as 0.00 for most populations. Average genetic diversity over loci and mean number of alleles in P. patens populations were significantly correlated with population size, suggesting severe genetic drift. The results of AMOVA point to higher levels of variation within populations than between populations.The results of Structure and PCoA analyses suggest that the genetic structure of the studied P. patens populations fall into three clusters corresponding to geographical regions. The most isolated populations (mostly from Romania) formed a separate group with a homogeneous gene pool located at the southern, steppic part of the distribution range. Baltic, mostly Polish, populations fall into two genetic groups which were not fully compatible with their geographic distribution.Our results indicate the serious genetic depauperation of P. patens in the western part of its range, even hinting at an ongoing extinction vortex. Therefore, special conservation attention is required to maintain the populations of this highly endangered species of European Community interest.
Collapse
Affiliation(s)
- Monika Szczecińska
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Gabor Sramko
- Department of Botany, University of Debrecen, Debrecen, Hungary
- MTA-ELTE-MTM Ecology Research Group, Budapest, Hungary
| | - Katarzyna Wołosz
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Jakub Sawicki
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
- Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic
| |
Collapse
|
7
|
Ursenbacher S, Guillon M, Cubizolle H, Dupoué A, Blouin-Demers G, Lourdais O. Postglacial recolonization in a cold climate specialist in western Europe: patterns of genetic diversity in the adder (Vipera berus) support the central-marginal hypothesis. Mol Ecol 2015; 24:3639-51. [PMID: 26053307 DOI: 10.1111/mec.13259] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 05/20/2015] [Accepted: 05/27/2015] [Indexed: 02/03/2023]
Abstract
Understanding the impact of postglacial recolonization on genetic diversity is essential in explaining current patterns of genetic variation. The central-marginal hypothesis (CMH) predicts a reduction in genetic diversity from the core of the distribution to peripheral populations, as well as reduced connectivity between peripheral populations. While the CMH has received considerable empirical support, its broad applicability is still debated and alternative hypotheses predict different spatial patterns of genetic diversity. Using microsatellite markers, we analysed the genetic diversity of the adder (Vipera berus) in western Europe to reconstruct postglacial recolonization. Approximate Bayesian Computation (ABC) analyses suggested a postglacial recolonization from two routes: a western route from the Atlantic Coast up to Belgium and a central route from the Massif Central to the Alps. This cold-adapted species likely used two isolated glacial refugia in southern France, in permafrost-free areas during the last glacial maximum. Adder populations further from putative glacial refugia had lower genetic diversity and reduced connectivity; therefore, our results support the predictions of the CMH. Our study also illustrates the utility of highly variable nuclear markers, such as microsatellites, and ABC to test competing recolonization hypotheses.
Collapse
Affiliation(s)
- Sylvain Ursenbacher
- Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, Basel, 4056, Switzerland
| | - Michaël Guillon
- Centre d'Etudes Biologiques de Chizé, CNRS UMR 7372, Villiers en Bois, 79360, France.,Université de Poitiers, 40 Avenue du Recteur Pineau, Poitiers, 86022, France
| | - Hervé Cubizolle
- Université de Lyon, EVS-ISTHME UMR 5600 CNRS, 6 rue Basse des Rives, Saint-Etienne Cedex 2, 42023, France
| | - Andréaz Dupoué
- Centre d'Etudes Biologiques de Chizé, CNRS UMR 7372, Villiers en Bois, 79360, France
| | | | - Olivier Lourdais
- Centre d'Etudes Biologiques de Chizé, CNRS UMR 7372, Villiers en Bois, 79360, France.,School of Life Sciences, Arizona State University, Tempe, AZ, 85287-4501, USA
| |
Collapse
|
8
|
Genetic and fitness consequences of interpopulation mating in Dianthus guliae Janka: conservation implications for severely depleted and isolated plant populations. CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0727-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
9
|
Whitlock R. Relationships between adaptive and neutral genetic diversity and ecological structure and functioning: a meta-analysis. THE JOURNAL OF ECOLOGY 2014; 102:857-872. [PMID: 25210204 PMCID: PMC4142011 DOI: 10.1111/1365-2745.12240] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/20/2014] [Indexed: 05/20/2023]
Abstract
Understanding the effects of intraspecific genetic diversity on the structure and functioning of ecological communities is a fundamentally important part of evolutionary ecology and may also have conservation relevance in identifying the situations in which genetic diversity coincides with species-level diversity.Early studies within this field documented positive relationships between genetic diversity and ecological structure, but recent studies have challenged these findings. Conceptual synthesis has been hampered because studies have used different measures of intraspecific variation (phenotypically adaptive vs. neutral) and have considered different measures of ecological structure in different ecological and spatial contexts. The aim of this study is to strengthen conceptual understanding by providing an empirical synthesis quantifying the relationship between genetic diversity and ecological structure.Here, I present a meta-analysis of the relationship between genetic diversity within plant populations and the structure and functioning of associated ecological communities (including 423 effect sizes from 70 studies). I used Bayesian meta-analyses to examine (i) the strength and direction of this relationship, (ii) the extent to which phenotypically adaptive and neutral (molecular) measures of diversity differ in their association with ecological structure and (iii) variation in outcomes among different measures of ecological structure and in different ecological contexts.Effect sizes measuring the relationship between adaptive diversity (genotypic richness) and both community- and ecosystem-level ecological responses were small, but significantly positive. These associations were supported by genetic effects on species richness and productivity, respectively.There was no overall association between neutral genetic diversity and measures of ecological structure, but a positive correlation was observed under a limited set of demographic conditions. These results suggest that adaptive and neutral genetic diversity should not be treated as ecologically equivalent measures of intraspecific variation.Synthesis. This study advances the debate over whether relationships between genetic diversity and ecological structure are either simply positive or negative, by showing how the strength and direction of these relationships changes with different measures of diversity and in different ecological contexts. The results provide a solid foundation for assessing when and where an expanded synthesis between ecology and genetics will be most fruitful.
Collapse
Affiliation(s)
- Raj Whitlock
- Institute of Integrative Biology, University of LiverpoolLiverpool, L69 7ZB, UK
| |
Collapse
|
10
|
|
11
|
Castilla AR, Alonso C, Herrera CM. Genetic structure of the shrub Daphne laureola across the Baetic Ranges, a Mediterranean glacial refugium and biodiversity hotspot. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:515-524. [PMID: 22188205 DOI: 10.1111/j.1438-8677.2011.00521.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Distribution margins constitute areas particularly prone to random and/or adaptive intraspecific differentiation in plants. This trend may be particularly marked in species discontinuously distributed across mountain ranges, where sharp geographic isolation gradients and habitat boundaries will enhance genetic isolation among populations. In this study, we analysed the level of neutral genetic differentiation among populations of the long-lived shrub Daphne laureola (Thymelaeaceae) across the Baetic Ranges, a glacial refugium and biodiversity hotspot in the western Mediterranean Basin. Within this area, core and marginal populations of D. laureola were compared with regard to their spatial isolation, size, genetic diversity and differentiation. A spatially explicit analysis conducted on the vast majority of the species' known populations in the study area (N = 111) showed that marginal populations (western and eastern) present larger spatial isolation than core populations, but are not smaller. We compared genetic diversity and differentiation between core and marginal populations using a subsample of 15 populations and 225 amplified fragment length polymorphism (AFLP) markers. Core and marginal populations did not differ in genetic diversity, probably because of the occurrence of large populations on the local margins. Western populations were strongly differentiated from the other populations. In addition, spatial and genetic differentiation among populations was larger on the western margin. Eastern populations constituted a genetically homogeneous group closely related to core populations, despite their greater spatial isolation. Results suggest that studies on phenotypic differentiation between core and marginal populations of D. laureola, and presumably other species having discontinuous distributions across the Baetic ranges, should take into account geographical differences in levels of genetic differentiation between the different distribution borders.
Collapse
Affiliation(s)
- A R Castilla
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain.
| | | | | |
Collapse
|
12
|
Dai Q, Fu J. When central populations exhibit more genetic diversity than peripheral populations: A simulation study. CHINESE SCIENCE BULLETIN-CHINESE 2011. [DOI: 10.1007/s11434-011-4605-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
13
|
Castilla AR, Alonso C, Herrera CM. Exploring local borders of distribution in the shrub Daphne laureola: Individual and populations traits. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2011. [DOI: 10.1016/j.actao.2011.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
14
|
|
15
|
HOBAN SEANM, BORKOWSKI DANIELS, BROSI SUNSHINEL, McCLEARY TIMS, THOMPSON LAURAM, McLACHLAN JASONS, PEREIRA MARIEA, SCHLARBAUM SCOTTE, ROMERO-SEVERSON JEANNE. Range-wide distribution of genetic diversity in the North American tree Juglans cinerea: a product of range shifts, not ecological marginality or recent population decline. Mol Ecol 2010; 19:4876-91. [DOI: 10.1111/j.1365-294x.2010.04834.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
16
|
Thompson JD, Gaudeul M, Debussche M. Conservation value of sites of hybridization in peripheral populations of rare plant species. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2010; 24:236-245. [PMID: 19659685 DOI: 10.1111/j.1523-1739.2009.01304.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Populations at the periphery of a species' range are of interest to conservation biologists because they can show marked genetic differentiation from populations at the center of a range and because of potential hybridization among rare and common species. We examined two closely related Cyclamen species. One is a narrow endemic, and the other is more geographically widespread (both protected by law in continental southern France). We used floral traits and genetic variability to test for hybridization among the species in peripheral populations of the rare species. The species co-occurred on Corsica in a disjunct, peripheral part of the distribution of the endemic species and in an ecologically marginal area for the widespread species. The two species have hybridized and the endemic species showed high levels of introgression with its widespread congener. Genetic and floral variability in sites with both species was markedly higher than in sites with a single species. Our results highlight the need for a conservation strategy that integrates hybrid populations because they represent a source of novel diversity that may have adaptive potential.
Collapse
Affiliation(s)
- John D Thompson
- UMR 5175 Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, 1919 route de Mende, 34293 Montpellier cedex 5, France.
| | | | | |
Collapse
|
17
|
Jiménez A, Quintanilla LG, Pajarón S, Pangua E. Genetic variation in the allotetraploid Dryopteris corleyi (Dryopteridaceae) and its diploid parental species in the Iberian Peninsula. AMERICAN JOURNAL OF BOTANY 2009; 96:1880-1886. [PMID: 21622309 DOI: 10.3732/ajb.0900055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Studies on genetic diversity help us to unveil the evolutionary processes of species and populations and can explain several traits of diploid-polyploid complexes such as their distributions, their breeding systems, and the origin of polyploids. We examined the allozyme variation of Dryopteris aemula and D. oreades, diploid ferns with highly fragmented habitats, and the allotetraploid D. corleyi to (1) analyze the putative relationship between both diploids and the tetraploid, (2) compare the levels of genetic variation among species and determine their causes, and (3) assess the breeding system of these taxa. The allozymic pattern of D. corleyi confirms that it derived from D. aemula and D. oreades. The lack of genetic diversity in D. aemula, a species of lowland habitats, may be due to genetic drift associated with the contraction of populations in the last glaciation. By contrast, the alpine D. oreades had moderate intrapopulation genetic variation, which may derive from the expansion of populations during the last glaciation. In the latter species, low interpopulational variation suggested effective gene flow (spore exchange), and genotype frequencies in Hardy-Weinberg equilibrium indicated cross-fertilization of gametophytes. Evolutionary history appears to be an essential element in the interpretation of genetic variation of highly fragmented populations.
Collapse
Affiliation(s)
- Ares Jiménez
- Departamento de Biología y Geología, Universidad Rey Juan Carlos, E-28933 Móstoles, Spain
| | | | | | | |
Collapse
|
18
|
Fine-scale genetic structure and marginal processes in an expanding population of Biscutella laevigata L. (Brassicaceae). Heredity (Edinb) 2008; 101:536-42. [PMID: 18781166 DOI: 10.1038/hdy.2008.95] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Evolutionary processes acting at the expanding margins of a species' range are still poorly understood. Genetic drift is considered prevalent in marginal populations, and the maintenance of genetic diversity during recolonization might seem puzzling. To investigate such processes, a fine-scale investigation of 219 individuals was performed within a population of Biscutella laevigata (Brassicaceae), located at the leading edge of its range. The survey used amplified fragment length polymorphisms (AFLPs). As commonly reported across the whole species distribution range, individual density and genetic diversity decreased along the local axis of recolonization of this expanding population, highlighting the enduring effect of the historical colonization on present-day diversity. The self-incompatibility system of the plant may have prevented local inbreeding in newly found patches and sustained genetic diversity by ensuring gene flow from established populations. Within the more continuously populated region, spatial analysis of genetic structure revealed restricted gene flow among individuals. The distribution of genotypes formed a mosaic of relatively homogenous patches within the continuous population. This pattern could be explained by a history of expansion by long-distance dispersal followed by fine-scale diffusion (that is, a stratified dispersal combination). The secondary contact among expanding patches apparently led to admixture among differentiated genotypes where they met (that is, a reshuffling effect). This type of dynamics could explain the maintenance of genetic diversity during recolonization.
Collapse
|
19
|
Yakimowski SB, Eckert CG. Populations do not become less genetically diverse or more differentiated towards the northern limit of the geographical range in clonal Vaccinium stamineum (Ericaceae). THE NEW PHYTOLOGIST 2008; 180:534-544. [PMID: 18694448 DOI: 10.1111/j.1469-8137.2008.02582.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Geographically peripheral populations are expected to exhibit lower genetic diversity and higher differentiation than central populations because of their smaller size and greater spatial isolation. In plants, a shift from sexual to clonal asexual reproduction may further reduce diversity and increase differentiation. Here, these predictions were tested by assaying 36 inter-simple sequence repeat (ISSR) polymorphisms in 21 populations of the woody, clonal plant Vaccinium stamineum in eastern North America, from the range center to its northern limit where it has 'threatened' status. Populations decline in frequency, but not size or sexual reproductive output, across the range. Within-population diversity did not decline towards range margins. Modest genetic differentiation among populations increased slightly towards range margins and in small populations with high clonal propagation and low seed production, although none of these trends was significant. Low seed production and high clonal propagation were not associated with large-scale clonal spread. By combining demographic and genetic data, this study determined that increased population isolation, rather than reduced population size, can account for the weak increase in genetic differentiation at range margins.
Collapse
Affiliation(s)
- Sarah B Yakimowski
- Department of Biology, Queen's University, Kingston, Ontario K7 L 3N6 Canada
| | | |
Collapse
|
20
|
PUŞCAŞ M, CHOLER P, TRIBSCH A, GIELLY L, RIOUX D, GAUDEUL M, TABERLET P. Post-glacial history of the dominant alpine sedge Carex curvula in the European Alpine System inferred from nuclear and chloroplast markers. Mol Ecol 2008; 17:2417-29. [DOI: 10.1111/j.1365-294x.2008.03751.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
21
|
Eckert CG, Samis KE, Lougheed SC. Genetic variation across species' geographical ranges: the central-marginal hypothesis and beyond. Mol Ecol 2008; 17:1170-88. [PMID: 18302683 DOI: 10.1111/j.1365-294x.2007.03659.x] [Citation(s) in RCA: 779] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There is growing interest in quantifying genetic population structure across the geographical ranges of species to understand why species might exhibit stable range limits and to assess the conservation value of peripheral populations. However, many assertions regarding peripheral populations rest on the long-standing but poorly tested supposition that peripheral populations exhibit low genetic diversity and greater genetic differentiation as a consequence of smaller effective population size and greater geographical isolation relative to geographically central populations. We reviewed 134 studies representing 115 species that tested for declines in within-population genetic diversity and/or increases in among-population differentiation towards range margins using nuclear molecular genetic markers. On average, 64.2% of studies detected the expected decline in diversity, 70.2% of those that tested for it showed increased differentiation and there was a positive association between these trends. In most cases, however, the difference in genetic diversity between central and peripheral population was not large. Although these results were consistent across plants and animals, strong taxonomic and biogeographical biases in the available studies call for a cautious generalization of these results. Despite the large number of studies testing these simple predictions, very few attempted to test possible mechanisms causing reduced peripheral diversity or increased differentiation. Almost no study incorporated a phylogeographical framework to evaluate historical influences on contemporary genetic patterns. Finally, there has been little effort to test whether these geographical trends in putatively neutral variation at marker loci are reflected by quantitative genetic trait variation, which is likely to influence the adaptive potential of populations across the geographical range.
Collapse
Affiliation(s)
- C G Eckert
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
| | | | | |
Collapse
|
22
|
Darling E, Samis KE, Eckert CG. Increased seed dispersal potential towards geographic range limits in a Pacific coast dune plant. THE NEW PHYTOLOGIST 2008; 178:424-435. [PMID: 18194144 DOI: 10.1111/j.1469-8137.2007.02349.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Dispersal may be favoured at geographic range edges by unstable population and metapopulation dynamics. However, dispersal may also evolve in response to geographic variation in other life-history traits, especially the mating system. Here, increased dispersal at range margins was tested for with a range-wide analysis of seed dispersal and mating system traits in Abronia umbellata, a plant endemic to Pacific coastal dunes of North America. Seeds disperse within winged anthocarps. Anthocarps from 34 populations varied widely in wing size (mass-corrected wing index). Wing index correlated negatively with threshold wind velocity for dispersal in wind tunnel tests, suggesting that wings facilitate tumbling over open sandy substrate. As predicted, wing index increased and threshold velocity decreased towards both range limits. Flower size, herkogamy and self-incompatibility declined towards range limits, indicating a shift to self-fertilization, and flower size and wing index correlated negatively. However, the increase in wing index towards range limits remained after statistically controlling flower size. These results are consistent with selection favouring dispersal at range margins. The evolutionary lability of dispersal across the range may affect the interaction between selection and gene flow in the establishment and maintenance of geographic range limits.
Collapse
Affiliation(s)
- Emily Darling
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Karen E Samis
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | | |
Collapse
|
23
|
Adding a third dimension to the edge of a species' range: altitude and genetic structuring in mountainous landscapes. Heredity (Edinb) 2007; 100:275-85. [PMID: 17940546 DOI: 10.1038/sj.hdy.6801072] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In addition to the topographical and ecological barriers, other landscape features may also subtly influence the patterns of gene flow and spatial genetic structuring at species' borders. This paper focuses on the role played by altitudinal gradients that characterize mountainous landscapes. We formulate and test the hypothesis that when the distribution boundaries of plant species intersect mountainous landscapes, altitudinal gradients in ecological conditions may considerably enhance population subdivision and genetic structuring at the regional level. Using amplified fragment length polymorphism markers, we studied genetic diversity and differentiation in a set of 21 peripheral populations of the evergreen shrub Lavandula latifolia Med. (Labiatae) at its southernmost distribution limit in the Betic mountain ranges of southern Spain. Population size and abundance, and within-population genetic diversity, varied predictably with altitude, being highest at middle elevations and declining steadily towards both the upper and lower altitudinal distribution margins. Genetic differentiation tended to follow the opposite trend. These altitudinal patterns result from variation with elevation in the relative influence of gene flow and drift on the distribution of genetic variation. Genetic drift prevails around the upper and lower altitudinal limits, whereas a situation closer to a drift-gene flow equilibrium exists at the center of the altitudinal distribution. Altitudinal variation in the relative influences of gene flow and drift appears as an essential element in the interpretation of regional genetic structuring of L. latifolia at its mountainous distribution edge, and a factor which may influence the evolutionary potential of peripheral populations and the likelihood of local adaptation.
Collapse
|
24
|
Ramesha BT, Ravikanth G, Nageswara Rao M, Ganeshaiah KN, Uma Shaanker R. Genetic structure of the rattan Calamus thwaitesii in core, buffer and peripheral regions of three protected areas in central Western Ghats, India: do protected areas serve as refugia for genetic resources of economically important plants? J Genet 2007; 86:9-18. [PMID: 17656844 DOI: 10.1007/s12041-007-0002-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Given the increasing anthropogenic pressures on forests, the various protected areas--national parks, sanctuaries, and biosphere reserves--serve as the last footholds for conserving biological diversity. However, because protected areas are often targeted for the conservation of selected species, particularly charismatic animals, concerns have been raised about their effectiveness in conserving nontarget taxa and their genetic resources. In this paper, we evaluate whether protected areas can serve as refugia for genetic resources of economically important plants that are threatened due to extraction pressures. We examine the population structure and genetic diversity of an economically important rattan, Calamus thwaitesii, in the core, buffer and peripheral regions of three protected areas in the central Western Ghats, southern India. Our results indicate that in all the three protected areas, the core and buffer regions maintain a better population structure, as well as higher genetic diversity, than the peripheral regions of the protected area. Thus, despite the escalating pressures of extraction, the protected areas are effective in conserving the genetic resources of rattan. These results underscore the importance of protected areas in conservation of nontarget species and emphasize the need to further strengthen the protected-area network to offer refugia for economically important plant species.
Collapse
Affiliation(s)
- B T Ramesha
- Conservation Genetics Laboratory, Department of Crop Physiology, University of Agricultural Sciences, Bangalore 560 065, India
| | | | | | | | | |
Collapse
|
25
|
Samis KE, Eckert CG. TESTING THE ABUNDANT CENTER MODEL USING RANGE-WIDE DEMOGRAPHIC SURVEYS OF TWO COASTAL DUNE PLANTS. Ecology 2007; 88:1747-58. [PMID: 17645021 DOI: 10.1890/06-1153.1] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It is widely accepted that species are most abundant at the center of their geographic ranges and become progressively rarer toward range limits. Although the abundant center model (ACM) has rarely been tested with range-wide surveys, it influences much thinking about the ecology and evolution of species' distributions. We tested ACM predictions using two unrelated but ecologically similar plants, Camissonia cheiranthifolia and Abronia umbellata. We intensively sampled both throughout their one-dimensional distributions within the Pacific coastal dunes of North America, from northern Baja California, Mexico, to southern Oregon, USA. Data from > 1100 herbarium specimens indicated that these limits have been stable for at least the last 100 years. Range-wide field surveys detected C. cheiranthifolia at 87% of 124 sites and A. umbellata at 54% of 113 sites, but site occupancy did not decline significantly toward range limits for either species. Permutation analysis did not detect a significant fit of geographical variation in local density to the ACM. Mean density did not correlate negatively with mean individual performance (plant size or number of seeds/plant), probably because both species occur at low densities. Although size and seeds per plant varied widely, central populations tended to have the highest values for size only. For C. cheiranthifolia, we observed asymmetry in the pattern of variation between the northern and southern halves of the range consistent with the long-standing prediction that range limits are imposed by different ecological factors in different parts of the geographical distribution. However, these asymmetries were difficult to interpret and likely reflect evolutionary differentiation as well as plastic responses to ecological variation. Both density and seeds per plant contributed to variation in seed production per unit area. In C. cheiranthifolia only, sites with highest seed production tended to occur at the range center, as predicted by the ACM and assumed by theory proposing that range limits evolve via antagonism between natural selection and gene flow.
Collapse
Affiliation(s)
- Karen E Samis
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | | |
Collapse
|
26
|
Honnay O, Jacquemyn H. Susceptibility of common and rare plant species to the genetic consequences of habitat fragmentation. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2007; 21:823-31. [PMID: 17531059 DOI: 10.1111/j.1523-1739.2006.00646.x] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Small plant populations are more prone to extinction due to the loss of genetic variation through random genetic drift, increased selfing, and mating among related individuals. To date, most researchers dealing with genetic erosion in fragmented plant populations have focused on threatened or rare species. We raise the question whether common plant species are as susceptible to habitat fragmentation as rare species. We conducted a formal meta-analysis of habitat fragmentation studies that reported both population size and population genetic diversity. We estimated the overall weighted mean and variance of the correlation coefficients among four different measures of genetic diversity and plant population size. We then tested whether rarity, mating system, and plant longevity are potential moderators of the relationship between population size and genetic diversity. Mean gene diversity, percent polymorphic loci, and allelic richness across studies were positively and highly significantly correlated with population size, whereas no significant relationship was found between population size and the inbreeding coefficient. Genetic diversity of self-compatible species was less affected by decreasing population size than that of obligate outcrossing and self-compatible but mainly outcrossing species. Longevity did not affect the population genetic response to fragmentation. Our most important finding, however, was that common species were as, or more, susceptible to the population genetic consequences of habitat fragmentation than rare species, even when historically or naturally rare species were excluded from the analysis. These results are dramatic in that many more plant species than previously assumed may be vulnerable to genetic erosion and loss of genetic diversity as a result of ongoing fragmentation processes. This implies that many fragmented habitats have become unable to support plant populations that are large enough to maintain a mutation-drift balance and that occupied habitat fragments have become too isolated to allow sufficient gene flow to enable replenishment of lost alleles.
Collapse
Affiliation(s)
- Olivier Honnay
- University of Leuven, Biology Department, Laboratory of Plant Ecology, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium.
| | | |
Collapse
|
27
|
Arnaud-Haond S, Teixeira S, Massa SI, Billot C, Saenger P, Coupland G, Duarte CM, Serrão EA. Genetic structure at range edge: low diversity and high inbreeding in Southeast Asian mangrove (Avicennia marina) populations. Mol Ecol 2006; 15:3515-25. [PMID: 17032254 DOI: 10.1111/j.1365-294x.2006.02997.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding the genetic composition and mating systems of edge populations provides important insights into the environmental and demographic factors shaping species' distribution ranges. We analysed samples of the mangrove Avicennia marina from Vietnam, northern Philippines and Australia, with microsatellite markers. We compared genetic diversity and structure in edge (Southeast Asia, and Southern Australia) and core (North and Eastern Australia) populations, and also compared our results with previously published data from core and southern edge populations. Comparisons highlighted significantly reduced gene diversity and higher genetic structure in both margins compared to core populations, which can be attributed to very low effective population size, pollinator scarcity and high environmental pressure at distribution margins. The estimated level of inbreeding was significantly higher in northeastern populations compared to core and southern populations. This suggests that despite the high genetic load usually associated with inbreeding, inbreeding or even selfing may be advantageous in margin habitats due to the possible advantages of reproductive assurance, or local adaptation. The very high level of genetic structure and inbreeding show that populations of A. marina are functioning as independent evolutionary units more than as components of a metapopulation system connected by gene flow. The combinations of those characteristics make these peripheral populations likely to develop local adaptations and therefore to be of particular interest for conservation strategies as well as for adaptation to possible future environmental changes.
Collapse
Affiliation(s)
- S Arnaud-Haond
- CCMAR-CIMAR Laboratório Associado, Universidade do Algarve, Gambelas, 8005-139, Faro, Portugal.
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Alleaume-Benharira M, Pen IR, Ronce O. Geographical patterns of adaptation within a species' range: interactions between drift and gene flow. J Evol Biol 2006; 19:203-15. [PMID: 16405592 DOI: 10.1111/j.1420-9101.2005.00976.x] [Citation(s) in RCA: 224] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We use individual-based stochastic simulations and analytical deterministic predictions to investigate the interaction between drift, natural selection and gene flow on the patterns of local adaptation across a fragmented species' range under clinally varying selection. Migration between populations follows a stepping-stone pattern and density decreases from the centre to the periphery of the range. Increased migration worsens gene swamping in small marginal populations but mitigates the effect of drift by replenishing genetic variance and helping purge deleterious mutations. Contrary to the deterministic prediction that increased connectivity within the range always inhibits local adaptation, simulations show that low intermediate migration rates improve fitness in marginal populations and attenuate fitness heterogeneity across the range. Such migration rates are optimal in that they maximize the total mean fitness at the scale of the range. Optimal migration rates increase with shallower environmental gradients, smaller marginal populations and higher mutation rates affecting fitness.
Collapse
Affiliation(s)
- M Alleaume-Benharira
- Laboratoire Génétique et Environnement, Université de Montpellier II, Institut des Sciences de l'Evolution, Montpellier Cedex, France.
| | | | | |
Collapse
|
29
|
|
30
|
VAN ROSSUM FABIENNE, PRENTICE HONORC. Structure of allozyme variation in Nordic Silene nutans (Caryophyllaceae): population size, geographical position and immigration history. Biol J Linn Soc Lond 2004. [DOI: 10.1111/j.1095-8312.2003.00301.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|