scholarly journals Comparative epigenetic and genetic spatial structure of the perennial herb Helleborus foetidus : Isolation by environment, isolation by distance, and functional trait divergence

2017 ◽  
Vol 104 (8) ◽  
pp. 1195-1204 ◽  
Author(s):  
Carlos M. Herrera ◽  
Mónica Medrano ◽  
Pilar Bazaga
Keyword(s):  
Spatial Structure ◽  
Isolation By Distance ◽  
Functional Trait ◽  
Perennial Herb ◽  
Helleborus Foetidus ◽  
Trait Divergence ◽  
Isolation By Environment

scholarly journals Genetic divergence correlates with the contemporary landscape in populations of Slimy Salamander (Plethodon glutinosus) species complex across the lower Piedmont and Coastal Plain of the southeastern United States

2018 ◽  
Vol 96 (11) ◽  
pp. 1244-1254 ◽  
Author(s):  
Walter H. Smith ◽  
Jessica A. Wooten ◽  
Carlos D. Camp ◽  
Dirk J. Stevenson ◽  
John B. Jensen ◽  
...  
Keyword(s):  
South Carolina ◽  
Genetic Distance ◽  
Principal Components ◽  
Coastal Plain ◽  
Genetic Divergence ◽  
Species Complex ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
Plethodon Glutinosus ◽  
Isolation By Environment

A primary goal of landscape genetics is to elucidate factors associated with genetic structure among populations. Among the important patterns identified have been isolation by distance (IBD), isolation by barrier (IBB), and isolation by environment (IBE). We tested hypotheses relating each of these possible patterns to genetic divergence in the Slimy Salamander (Plethodon glutinosus (Green, 1818)) species complex across the lower Piedmont and Coastal Plain of Georgia, USA, and adjacent areas of South Carolina, USA. We sequenced 2148 total bp, including three regions of the mitochondrial genome and a nuclear intron, and related genetic distance to GIS-derived surrogate variables representing possible IBD (geographic distance), IBE (principal components of 19 climate variables, watershed, and normalized difference vegetation index (NDVI)), and IBB (streams of fourth order and higher). Multiple matrix regression with randomization analysis indicated significant relationships between genetic distance and two principal components of climate, as well as NDVI. These results support roles for environment (IBE) in helping to drive genetic divergence in this group of salamanders. The absence of a significant influence of IBD and IBB was surprising. It is possible that the signal effects of geographic distance and barriers on genetic divergence may have been erased by more recent responses to the environment.

scholarly journals Genomic Adaptations to Salinity Resist Gene Flow in the Evolution of Floridian Watersnakes

2020 ◽  
Author(s):  
Rhett M Rautsaw ◽  
Tristan D Schramer ◽  
Rachel Acuña ◽  
Lindsay N Arick ◽  
Mark DiMeo ◽  
...  
Keyword(s):  
Gene Flow ◽  
Isolation By Distance ◽  
Species Boundaries ◽  
Selective Pressures ◽  
Nerodia Fasciata ◽  
Isolation By Environment ◽  
Significant Gene ◽  
Candidate Loci ◽  
Osmoregulatory Function ◽  
Ecological Differences

Abstract The migration-selection balance often governs the evolution of lineages, and speciation with gene flow is now considered common across the tree of life. Ecological speciation is a process that can facilitate divergence despite gene flow due to strong selective pressures caused by ecological differences; however, the exact traits under selection are often unknown. The transition from freshwater to saltwater habitats provides strong selection targeting traits with osmoregulatory function. Several lineages of North American watersnakes (Nerodia spp.) are known to occur in saltwater habitat and represent a useful system for studying speciation by providing an opportunity to investigate gene flow and evaluate how species boundaries are maintained or degraded. We use double digest restriction-site associated DNA sequencing to characterize the migration-selection balance and test for evidence of ecological divergence within the Nerodia fasciata-clarkii complex in Florida. We find evidence of high intraspecific gene flow with a pattern of isolation-by-distance underlying subspecific lineages. However, we identify genetic structure indicative of reduced gene flow between inland and coastal lineages suggesting divergence due to isolation-by-environment. This pattern is consistent with observed environmental differences where the amount of admixture decreases with increased salinity. Furthermore, we identify significantly enriched terms related to osmoregulatory function among a set of candidate loci, including several genes that have been previously implicated in adaptation to salinity stress. Collectively, our results demonstrate that ecological differences, likely driven by salinity, cause strong divergent selection which promotes divergence in the N. fasciata-clarkii complex despite significant gene flow.

scholarly journals Origins and Assembly of Malesian Rainforests

2019 ◽  
Vol 50 (1) ◽  
pp. 119-143 ◽  
Author(s):  
Robert M. Kooyman ◽  
Robert J. Morley ◽  
Darren M. Crayn ◽  
Elizabeth M. Joyce ◽  
Maurizio Rossetto ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Spatial Structure ◽  
Fossil Record ◽  
Functional Trait ◽  
Indian Plate ◽  
Evolutionary Origins ◽  
Australian Plate ◽  
Floristic Elements ◽  
Adaptive Radiations ◽  
Abundance And Diversity

Unraveling the origins of Malesia's once vast, hyperdiverse rainforests is a perennial challenge. Major contributions to rainforest assembly came from floristic elements carried on the Indian Plate and montane elementsfrom the Australian Plate (Sahul). The Sahul component is now understood to include substantial two-way exchanges with Sunda inclusive of lowland taxa. Evidence for the relative contributions of the great Asiatic floristic interchanges (GAFIs) with India and Sahul, respectively, to the flora of Malesia comes from contemporary lineage distributions, the fossil record, time-calibrated phylogenies, functional traits, and the spatial structure of genetic diversity. Functional-trait and biome conservatism are noted features of montane austral lineages from Sahul (e.g., diverse Podocarpaceae), whereas the abundance and diversity of lowland lineages, including Syzygium (Myrtaceae) and the Asian dipterocarps (Dipterocarpoideae), reflect a less well understood combination of dispersal, ecology, and adaptive radiations. Thus, Malesian rainforest assembly has been shaped by sharply contrasting evolutionary origins and biogeographic histories.

scholarly journals Evaluation of genetic isolation within an island flora reveals unusually widespread local adaptation and supports sympatric speciation

2014 ◽  
Vol 369 (1648) ◽  
pp. 20130342 ◽  
Author(s):  
Alexander S. T. Papadopulos ◽  
Maria Kaye ◽  
Céline Devaux ◽  
Helen Hipperson ◽  
Jackie Lighten ◽  
...  
Keyword(s):  
Gene Flow ◽  
Local Adaptation ◽  
Plant Species ◽  
Environmental Gradients ◽  
Isolation By Distance ◽  
Model Averaging ◽  
Dispersal Limitation ◽  
Population Divergence ◽  
Environmental Pressures ◽  
Isolation By Environment

It is now recognized that speciation can proceed even when divergent natural selection is opposed by gene flow. Understanding the extent to which environmental gradients and geographical distance can limit gene flow within species can shed light on the relative roles of selection and dispersal limitation during the early stages of population divergence and speciation. On the remote Lord Howe Island (Australia), ecological speciation with gene flow is thought to have taken place in several plant genera. The aim of this study was to establish the contributions of isolation by environment (IBE) and isolation by community (IBC) to the genetic structure of 19 plant species, from a number of distantly related families, which have been subjected to similar environmental pressures over comparable time scales. We applied an individual-based, multivariate, model averaging approach to quantify IBE and IBC, while controlling for isolation by distance (IBD). Our analyses demonstrated that all species experienced some degree of ecologically driven isolation, whereas only 12 of 19 species were subjected to IBD. The prevalence of IBE within these plant species indicates that divergent selection in plants frequently produces local adaptation and supports hypotheses that ecological divergence can drive speciation in sympatry.

scholarly journals Both functional trait divergence and trait plasticity confer polyploid advantage in changing environments

2018 ◽  
Author(s):  
Na Wei ◽  
Richard Cronn ◽  
Aaron Liston ◽  
Tia-Lynn Ashman
Keyword(s):  
Functional Trait ◽  
Leaf Functional Traits ◽  
Trait Divergence ◽  
Changing Environments ◽  
Fitness Advantage ◽  
Common Gardens ◽  
Trait Plasticity ◽  
Extensive Test ◽  
Wild Strawberry ◽  
Evolutionary Success

ABSTRACTPolyploidy, or whole genome duplication, exists in all eukaryotes and is thought to drive ecological and evolutionary success especially in plants. The mechanisms of polyploid success in ecologically relevant contexts, however, remain largely unknown. Here we conducted an extensive test of functional trait divergence and trait plasticity in conferring polyploid fitness advantage in changing environments by growing clonal replicates of a worldwide genotype collection of six polyploid and five diploid wild strawberry (Fragaria) species in three climatically different common gardens. Among leaf functional traits, we detected divergence in means but not plasticities between polyploids and diploids, suggesting that increased genomic redundancy does not necessarily translate into broader phenotypic amplitude in polyploids. Across the heterogeneous garden environments, however, polyploids exhibited fitness advantage, which was conferred by both trait means and adaptive trait plasticities, supporting a ‘jack-and-master’ hypothesis for polyploids. Our findings provide unparalleled insight into the prevalence and persistence of polyploidization.

scholarly journals Spatial, climate, and ploidy factors drive genomic diversity and resilience in the widespread grass Themeda triandra

2019 ◽  
Author(s):  
CW Ahrens ◽  
EA James ◽  
AD Miller ◽  
NC Aitken ◽  
JO Borevitz ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Isolation By Distance ◽  
Management Strategies ◽  
Genomic Variation ◽  
Genomic Diversity ◽  
List Type ◽  
Themeda Triandra ◽  
Reduced Representation ◽  
Isolation By Environment ◽  
Susceptible Populations

SummaryFragmented grassland ecosystems, and the species that shape them, are under immense pressure. Restoration and management strategies should include genetic diversity and adaptive capacity to improve success but these data are generally unavailable. Therefore, we use the foundational grass, Themeda triandra, to test how spatial, environmental, and ploidy factors shape patterns of genetic variation.We used reduced-representation genome sequencing on 487 samples from 52 locations to answer fundamental questions about how the distribution of genomic diversity and ploidy polymorphism supports adaptation to harsher climates. We explicitly quantified isolation-by-distance (IBD), isolation-by-environment (IBE), and predicted population genomic vulnerability in 2070.We found that a majority (54%) of the genomic variation could be attributed to IBD, while 22% of the genomic variation could be explained by four climate variables showing IBE. Results indicate that heterogeneous patterns of vulnerability across populations are due to genetic variation, multiple climate factors, and ploidy polymorphism, which lessened genomic vulnerability in the most susceptible populations.These results indicate that restoration and management of T. triandra should incorporate knowledge of genomic diversity and ploidy polymorphisms to increase the likelihood of population persistence and restoration success in areas that will become hotter and more arid.

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