scholarly journals Latitude delineates patterns of biogeography in terrestrialStreptomyces

2015 ◽  
Author(s):  
Mallory J Choudoir ◽  
James R Doroghazi ◽  
Daniel H Buckley
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Nucleotide Diversity ◽  
Spatial Scales ◽  
Allelic Diversity ◽  
Dispersal Limitation ◽  
Culture Collection ◽  
Diversity Gradient ◽  
Demographic Processes

SummaryWe examined the biogeography ofStreptomycesat regional spatial scales to identify factors that govern patterns of microbial diversity.Streptomycesare spore forming filamentous bacteria which are widespread in soil.Streptomycesstrains were isolated from perennial grass habitats sampled across a spatial scale of more than 6,000 km. Previous analysis of this geographically explicit culture collection provided evidence for a latitudinal diversity gradient inStreptomycesspecies. Here we evaluate the hypothesis that this latitudinal diversity gradient is a result of evolutionary dynamics associated with historical demographic processes. Historical demographic phenomena have genetic consequences that can be evaluated through analysis of population genetics. We applied population genetic approaches to analyze population structure in six of the most numerically abundant and geographically widespreadStreptomycesphylogroups from our culture collection.Streptomycespopulation structure varied at regional spatial scales and allelic diversity correlated with geographic distance. In addition, allelic diversity and gene flow are partitioned by latitude. Finally, we found that nucleotide diversity within phylogroups is negatively correlated with latitude. These results indicate that phylogroup diversification is constrained by dispersal limitation at regional spatial scales and they are consistent with the hypothesis that historical demographic processes have influenced the contemporary biogeography ofStreptomyces.Originality-Significance StatementWe provide the first population genetic evidence that patterns ofStreptomycesbiogeography, which manifest in geographically explicit patterns of gene flow and a latitudinal gradient of nucleotide diversity, result from dispersal limitation and regional diversification due to drift. This contribution elucidates evolutionary processes that underlie patterns of microbial biogeography.

scholarly journals Population structure and dispersal across small and large spatial scales in a direct developing marine isopod

2020 ◽  
Author(s):  
William S. Pearman ◽  
Sarah J. Wells ◽  
Olin K. Silander ◽  
Nikki E. Freed ◽  
James Dale
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Population Connectivity ◽  
Clear Pattern ◽  
Small Spatial Scale ◽  
Cook Strait ◽  
Genetic Break

AbstractMarine organisms generally exhibit one of two developmental modes: biphasic, with distinct adult and larval morphology, and direct development, in which larvae resemble adults. Developmental mode is thought to significantly influence dispersal, with direct developers expected to have much lower dispersal potential. However, in contrast to our relatively good understanding of dispersal and population connectivity for biphasic species, comparatively little is known about direct developers. In this study, we use a panel of 8,020 SNPs to investigate population structure and gene flow for a direct developing species, the New Zealand endemic marine isopod Isocladus armatus. On a small spatial scale (20 kms), gene flow between locations is extremely high and suggests an island model of migration. However, over larger spatial scales (600km), populations exhibit a clear pattern of isolation-by-distance. Because our sampling range is intersected by two well-known biogeographic barriers (the East Cape and the Cook Strait), our study provides an opportunity to understand how such barriers influence dispersal in direct developers. Our results indicate that I. armatus exhibits significant migration across these barriers, and suggests that ocean currents associated with these locations do not present a barrier to dispersal. Interestingly, we do find evidence of a north-south population genetic break occurring between Māhia and Wellington, two locations where there are no obvious biogeographic barriers between them. We conclude that developmental life history largely predicts dispersal in intertidal marine isopods. However, localised biogeographic processes can disrupt this expectation.

scholarly journals Genetic Diversity and Population Structure of Bermudagrass [Cynodon dactylon (L.) Pers.] along Latitudinal Gradients and the Relationship with Polyploidy Level

Diversity ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 135 ◽  
Author(s):  
Jingxue Zhang ◽  
Miaoli Wang ◽  
Zhipeng Guo ◽  
Yongzhuo Guan ◽  
Jianyu Liu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Cynodon Dactylon ◽  
Latitudinal Gradients ◽  
Wind Pollination ◽  
Ploidy Levels ◽  
Sexual And Asexual Reproduction ◽  
Genetic Pattern

Understanding the population genetic pattern and process of gene flow requires a detailed knowledge of how landscape characteristics structure populations. Although Cynodon dactylon (L.) Pers. (common bermudagrass) is widely distributed in the world, information on its genetic pattern and population structure along latitudinal gradients is limited. We tried to estimate the genetic diversity and genetic structure of C. dactylon along a latitudinal gradient across China. Genetic diversity among different ploidy levels was also compared in the study. The material used consisted of 296 C. dactylon individuals sampled from 16 geographic sites from 22°35′ N to 36°18′ N. Genetic diversity was estimated using 153 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. Higher within-population genetic diversity appeared at low-latitude, as well as having positive correlation with temperature and precipitation. The genetic diversity increased with the ploidy level of C. dactylon, suggesting polyploidy creates higher genetic diversity. No isolation by distance and notable admixture structure existed among populations along latitudes. Both seed dispersal (or vegetative organs) and extrinsic pollen played important roles for gene flow in shaping the spatial admixture population structure of C. dactylon along latitudes. In addition, populations were separated into three clusters according to ploidy levels. C. dactylon has many such biological characters of perennial growth, wind-pollination, polyploidy, low genetic differentiation among populations, sexual and asexual reproduction leading to higher genetic diversity, which gives it strong adaptability with its genetic patterns being very complex across all the sampled latitudes. The findings of this study are related to landscape population evolution, polyploidy speciation, preservation, and use of bermudagrass breeding.

scholarly journals Birds are islands for parasites

2014 ◽  
Vol 10 (8) ◽  
pp. 20140255 ◽  
Author(s):  
Jennifer A. H. Koop ◽  
Karen E. DeMatteo ◽  
Patricia G. Parker ◽  
Noah K. Whiteman
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Evolutionary Biology ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Island Populations ◽  
Louse Species ◽  
Parasite Populations

Understanding the mechanisms driving the extraordinary diversification of parasites is a major challenge in evolutionary biology. Co-speciation, one proposed mechanism that could contribute to this diversity is hypothesized to result from allopatric co-divergence of host–parasite populations. We found that island populations of the Galápagos hawk ( Buteo galapagoensis ) and a parasitic feather louse species ( Degeeriella regalis ) exhibit patterns of co-divergence across variable temporal and spatial scales. Hawks and lice showed nearly identical population genetic structure across the Galápagos Islands. Hawk population genetic structure is explained by isolation by distance among islands. Louse population structure is best explained by hawk population structure, rather than isolation by distance per se , suggesting that lice tightly track the recent population histories of their hosts. Among hawk individuals, louse populations were also highly structured, suggesting that hosts serve as islands for parasites from an evolutionary perspective. Altogether, we found that host and parasite populations may have responded in the same manner to geographical isolation across spatial scales. Allopatric co-divergence is likely one important mechanism driving the diversification of parasites.

scholarly journals Isolation by resistance across a complex coral reef seascape

2015 ◽  
Vol 282 (1812) ◽  
pp. 20151217 ◽  
Author(s):  
Luke Thomas ◽  
W. Jason Kennington ◽  
Michael Stat ◽  
Shaun P. Wilkinson ◽  
Johnathan T. Kool ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Divergence ◽  
Larval Dispersal ◽  
Population Genetic ◽  
Spatial Genetic Structure ◽  
Spatial Scales ◽  
Genetic Data ◽  
Genetic Structure Of Populations ◽  
Seascape Genetics

A detailed understanding of the genetic structure of populations and an accurate interpretation of processes driving contemporary patterns of gene flow are fundamental to successful spatial conservation management. The field of seascape genetics seeks to incorporate environmental variables and processes into analyses of population genetic data to improve our understanding of forces driving genetic divergence in the marine environment. Information about barriers to gene flow (such as ocean currents) is used to define a resistance surface to predict the spatial genetic structure of populations and explain deviations from the widely applied isolation-by-distance model. The majority of seascape approaches to date have been applied to linear coastal systems or at large spatial scales (more than 250 km), with very few applied to complex systems at regional spatial scales (less than 100 km). Here, we apply a seascape genetics approach to a peripheral population of the broadcast-spawning coral Acropora spicifera across the Houtman Abrolhos Islands, a high-latitude complex coral reef system off the central coast of Western Australia. We coupled population genetic data from a panel of microsatellite DNA markers with a biophysical dispersal model to test whether oceanographic processes could explain patterns of genetic divergence. We identified significant variation in allele frequencies over distances of less than 10 km, with significant differentiation occurring between adjacent sites but not between the most geographically distant ones. Recruitment probabilities between sites based on simulated larval dispersal were projected into a measure of resistance to connectivity that was significantly correlated with patterns of genetic divergence, demonstrating that patterns of spatial genetic structure are a function of restrictions to gene flow imposed by oceanographic currents. This study advances our understanding of the role of larval dispersal on the fine-scale genetic structure of coral populations across a complex island system and applies a methodological framework that can be tailored to suit a variety of marine organisms with a range of life-history characteristics.

scholarly journals Non-linear genetic diversity and notable population differentiation caused by low gene flow of bermudagrass [Cynodon dactylon (L.) Pers.] along longitude gradients

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11953
Author(s):  
Jing-Xue Zhang ◽  
Miaoli Wang ◽  
Jibiao Fan ◽  
Zhi-Peng Guo ◽  
Yongzhuo Guan ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Genetic Distance ◽  
Ploidy Level ◽  
Population Genetic ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Ploidy Levels ◽  
Population Genetic Diversity

Background Environmental variation related to ecological habitat is the main driver of plant adaptive divergence. Longitude plays an important role in the formation of plant population structure, indicating that environmental differentiation can significantly shape population structure. Methods Genetic diversity and population genetic structure were estimated using 105 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. A total of 249 C. dactylon (L.) Pers. (common bermudagrass) individuals were sampled from 13 geographic sites along the longitude (105°57′34″–119°27′06″E). Results There was no obvious linear trend of intra-population genetic diversity along longitude and the intra-population genetic diversity was not related to climate in this study. Low gene flow (Nm = 0.7701) meant a rich genetic differentiation among populations of C. dactylon along longitude gradients. Significantly positive Mantel correlation (r = 0.438, P = 0.001) was found between genetic distance and geographical interval while no significant partial Mantel correlation after controlling the effect of mean annual precipitation, which indicated geographic distance correlated with mean annual precipitation affect genetic distance. The genetic diversity of C. dactylon with higher ploidy level was higher than that with lower ploidy level and groups of individuals with higher ploidy level were separated further away by genetic distance from the lower ploidy levels. Understanding the different genetic bases of local adaptation comparatively between latitude and longitude is one of the core findings in the adaptive evolution of plants.

scholarly journals Maintenance of Sympatric and Allopatric Populations in Free-Living Terrestrial Bacteria

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Alexander B. Chase ◽  
Philip Arevalo ◽  
Eoin L. Brodie ◽  
Martin F. Polz ◽  
Ulas Karaoz ◽  
...  
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Isolation By Distance ◽  
Dispersal Limitation ◽  
Genomic Diversity ◽  
Gene Content ◽  
Microbial Populations ◽  
Free Living ◽  
Phylogenetic Structure ◽  
Isolation By Environment

ABSTRACT For free-living bacteria and archaea, the equivalent of the biological species concept does not exist, creating several obstacles to the study of the processes contributing to microbial diversification. These obstacles are particularly high in soil, where high bacterial diversity inhibits the study of closely related genotypes and therefore the factors structuring microbial populations. Here, we isolated strains within a single Curtobacterium ecotype from surface soil (leaf litter) across a regional climate gradient and investigated the phylogenetic structure, recombination, and flexible gene content of this genomic diversity to infer patterns of gene flow. Our results indicate that microbial populations are delineated by gene flow discontinuities, with distinct populations cooccurring at multiple sites. Bacterial population structure was further delineated by genomic features allowing for the identification of candidate genes possibly contributing to local adaptation. These results suggest that the genetic structure within this bacterium is maintained both by ecological specialization in localized microenvironments (isolation by environment) and by dispersal limitation between geographic locations (isolation by distance). IMPORTANCE Due to the promiscuous exchange of genetic material and asexual reproduction, delineating microbial species (and, by extension, populations) remains challenging. Because of this, the vast majority of microbial studies assessing population structure often compare divergent strains from disparate environments under varied selective pressures. Here, we investigated the population structure within a single bacterial ecotype, a unit equivalent to a eukaryotic species, defined as highly clustered genotypic and phenotypic strains with the same ecological niche. Using a combination of genomic and computational analyses, we assessed the phylogenetic structure, extent of recombination, and flexible gene content of this genomic diversity to infer patterns of gene flow. To our knowledge, this study is the first to do so for a dominant soil bacterium. Our results indicate that bacterial soil populations, similarly to those in other environments, are structured by gene flow discontinuities and exhibit distributional patterns consistent with both isolation by distance and isolation by environment. Thus, both dispersal limitation and local environments contribute to the divergence among closely related soil bacteria as observed in macroorganisms.

Contrasting population structures of three Pristis sawfishes with different patterns of habitat use

2017 ◽  
Vol 68 (3) ◽  
pp. 452 ◽  
Author(s):  
N. M. Phillips ◽  
J. A. Chaplin ◽  
S. C. Peverell ◽  
D. L. Morgan
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Habitat Use ◽  
Microsatellite Loci ◽  
Spatial Scales ◽  
Marine Waters ◽  
Male And Female ◽  
Entire Life ◽  
Population Structures ◽  
Using Data

This research demonstrates how population structure differs in elasmobranchs with different patterns of habitat use. Population structure was assessed using data at microsatellite loci in three species of Pristis sawfishes in northern Australian waters. Statistically significant population structure was found in each of P. clavata (FST = 0.021, F′ST = 0.151, P < 0.001) and P. zijsron (FST = 0.026, F′ST = 0.130, P < 0.001), which spend their entire life in marine waters. In contrast, there was no evidence of significant population structure in P. pristis, which uses freshwater rivers as juveniles and marine waters as adults (FST = 0.004, F′ST = 0.029, P = 0.210). When combined with the results of mtDNA analyses from a previous study, the results suggested that dispersal in P. pristis is male-biased, whereas both male and female gene flow are restricted at large spatial scales in each of P. clavata and P. zijsron in Australian waters. The present study has provided the first evidence of sex-biased dispersal in a sawfish.

scholarly journals A tale of two seas: contrasting patterns of population structure in the small-spotted catshark across Europe

2014 ◽  
Vol 1 (3) ◽  
pp. 140175 ◽  
Author(s):  
Chrysoula Gubili ◽  
David W. Sims ◽  
Ana Veríssimo ◽  
Paolo Domenici ◽  
Jim Ellis ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Spatial Scales ◽  
Sea Level Changes ◽  
Glacial Cycles ◽  
Mediterranean Populations ◽  
Population Reduction ◽  
The Mediterranean

Elasmobranchs represent important components of marine ecosystems, but they can be vulnerable to overexploitation. This has driven investigations into the population genetic structure of large-bodied pelagic sharks, but relatively little is known of population structure in smaller demersal taxa, which are perhaps more representative of the biodiversity of the group. This study explores spatial population genetic structure of the small-spotted catshark ( Scyliorhinus canicula ), across European seas. The results show significant genetic differences among most of the Mediterranean sample collections, but no significant structure among Atlantic shelf areas. The data suggest the Mediterranean populations are likely to have persisted in a stable and structured environment during Pleistocene sea-level changes. Conversely, the Northeast Atlantic populations would have experienced major changes in habitat availability during glacial cycles, driving patterns of population reduction and expansion. The data also provide evidence of male-biased dispersal and female philopatry over large spatial scales, implying complex sex-determined differences in the behaviour of elasmobranchs. On the basis of this evidence, we suggest that patterns of connectivity are determined by trends of past habitat stability that provides opportunity for local adaptation in species exhibiting philopatric behaviour, implying that resilience of populations to fisheries and other stressors may differ across the range of species.

scholarly journals Phylogeography of the Pacific Blueline Surgeonfish,Acanthurus nigroris, Reveals High Genetic Connectivity and a Cryptic Endemic Species in the Hawaiian Archipelago

2011 ◽  
Vol 2011 ◽  
pp. 1-17 ◽  
Author(s):  
Joseph D. DiBattista ◽  
Christie Wilcox ◽  
Matthew T. Craig ◽  
Luiz A. Rocha ◽  
Brian W. Bowen
Keyword(s):  
Gene Flow ◽  
Marine Protected Areas ◽  
Population Genetic ◽  
Spatial Scales ◽  
Genetic Connectivity ◽  
Species Pair ◽  
Hawaiian Archipelago ◽  
National Monument ◽  
Hawaiian Species ◽  
The Pacific

Understanding genetic connectivity is fundamental to the design of marine protected areas in the service of ecosystem-scale management. Here we evaluate such trends for a Pacific surgeonfish (Acanthurus nigroris;N=544) at two spatial scales: (1) within the Hawaiian archipelago, and (2) across the entire species range from the central to southwest Pacific. The mtDNA cytochromebdata reveal genetic divergence (d=0.041) between Hawaii and the rest of the Pacific range indicating a cryptic species pair, with one taxon endemic to Hawaii. Johnston Atoll, 1400 km SW of Hawaii, also has the Hawaiian species but is distinct from most Hawaiian locations in population genetic comparisons, indicating the limits of gene flow for this widespread reef species. No consistent population genetic differences were observed among Hawaiian sites or among the other Pacific island sites. We also detected a modest bias in gene flow from the southeast towards the northwest islands of the Hawaiian Archipelago, indicating that the Papahānaumokuākea Marine National Monument may be a recipient, rather than a source of propagules to replenish reef resources.

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