scholarly journals Sporadic Genetic Connectivity among Small Insular Populations of the Rare Geoendemic Plant Caulanthus amplexicaulis var. barbarae (Santa Barbara Jewelflower)

2019 ◽  
Vol 110 (5) ◽  
pp. 587-600
Author(s):  
A Millie Burrell ◽  
Jeffrey H R Goddard ◽  
Paul J Greer ◽  
Ryan J Williams ◽  
Alan E Pepper
Keyword(s):  
Gene Flow ◽  
Genetic Connectivity ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Isolated Populations ◽  
Long Distance ◽  
Population Sizes ◽  
History Of ◽  
Small Set ◽  
Nuclear Microsatellite

Abstract Globally, a small number of plants have adapted to terrestrial outcroppings of serpentine geology, which are characterized by soils with low levels of essential mineral nutrients (N, P, K, Ca, Mo) and toxic levels of heavy metals (Ni, Cr, Co). Paradoxically, many of these plants are restricted to this harsh environment. Caulanthus ampexlicaulis var. barbarae (Brassicaceae) is a rare annual plant that is strictly endemic to a small set of isolated serpentine outcrops in the coastal mountains of central California. The goals of the work presented here were to 1) determine the patterns of genetic connectivity among all known populations of C. ampexlicaulis var. barbarae, and 2) estimate contemporary effective population sizes (Ne), to inform ongoing genomic analyses of the evolutionary history of this taxon, and to provide a foundation upon which to model its future evolutionary potential and long-term viability in a changing environment. Eleven populations of this taxon were sampled, and population-genetic parameters were estimated using 11 nuclear microsatellite markers. Contemporary effective population sizes were estimated using multiple methods and found to be strikingly small (typically Ne < 10). Further, our data showed that a substantial component of genetic connectivity of this taxon is not at equilibrium, and instead showed sporadic gene flow. Several lines of evidence indicate that gene flow between isolated populations is maintained through long-distance seed dispersal (e.g., >1 km), possibly via zoochory.

scholarly journals Human-driven genetic differentiation in a managed red deer population

2021 ◽  
Vol 67 (2) ◽  
Author(s):  
Gerald Reiner ◽  
C. Klein ◽  
M. Lang ◽  
H. Willems
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Red Deer ◽  
Young Male ◽  
Genetic Exchange ◽  
Genetic Connectivity ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Population Sizes ◽  
Populated Region

AbstractNineteen red deer areas in a densely populated region with a huge network of fenced motorways and the division into administrative management units (AMUs) with restricted ecological connectivity were investigated. In the season 2018/2019, a total of 1291 red deer samples (on average 68 per area) were collected and genotyped using 16 microsatellite markers. The results show a clear genetic differentiation between most of the AMUs. Fourteen AMUs may be combined into four regions with a considerable internal genetic exchange. Five areas were largely isolated or showed only a limited gene flow with neighbouring areas. Ten of the 19 AMUs had an effective population size below 100. Effective population sizes greater than 500–1000, required to maintain the evolutionary potential and a long-term adaptation potential, were not achieved by any of the studied AMUs, even when AMUs with an appreciable genetic exchange were aggregated. Substantial genetic differentiation between areas can be associated with the presence of landscape barriers hindering gene flow, but also with the maintenance of ‘red deer–free’ areas. Efforts to sustainably preserve the genetic diversity of the entire region should therefore focus on measures ensuring genetic connectivity. Opportunities for this goal arise from the establishment of game bridges over motorways and from the protection of young male stags migrating through the statutory ‘red deer–free’ areas.

scholarly journals Assessing genetic diversity and connectivity in a tule elk (Cervus canadensis nannodes) metapopulation in Northern California

2021 ◽  
Author(s):  
Thomas J. Batter ◽  
Joshua P. Bush ◽  
Benjamin N. Sacks
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Population Expansion ◽  
Active Management ◽  
Genetic Connectivity ◽  
Effective Population ◽  
Sex Marker ◽  
Cervus Canadensis ◽  
Population Sizes ◽  
Tule Elk

AbstractThe tule elk (Cervus canadensis nannodes) is a California endemic subspecies that experienced an extreme bottleneck (potentially two individuals) in the mid-1800s. Through active management, including reintroductions, the subspecies has grown to approximately 6000 individuals spread across 22 recognized populations. The populations tend to be localized and separated by unoccupied intervening habitat, prompting targeted translocations to ensure gene flow. However, little is known about the genetic status or connectivity among adjacent populations in the absence of active translocations. We used 19 microsatellites and a sex marker to obtain baseline data on the genetic effective population sizes and functional genetic connectivity of four of these populations, three of which were established since the 1980s and one of which was established ~ 100 years ago. A Bayesian assignment approach suggested the presence of 5 discrete genetic clusters, which corresponded to the four primary populations and two subpopulations within the oldest of them. Effective population sizes ranged from 15 (95% CI 10–22) to 51 (95% CI 32–88). We detected little or no evidence of gene flow among most populations. Exceptions were a signature of unidirectional gene flow to one population founded by emigrants of the other 30 years earlier, and bidirectional gene flow between subpopulations within the oldest population. We propose that social cohesion more than landscape characteristics explained population structure, which developed over many generations corresponding to population expansion. Whether or which populations can grow and reach sufficient effective population sizes on their own or require translocations to maintain genetic diversity and population growth is unclear. In the future, we recommend pairing genetic with demographic monitoring of these and other reintroduced elk populations, including targeted monitoring following translocations to evaluate their effects and necessity.

scholarly journals The Genetic History of France

2019 ◽  
Author(s):  
Aude Saint Pierre ◽  
Joanna Giemza ◽  
Matilde Karakachoff ◽  
Isabel Alves ◽  
Philippe Amouyel ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Demographic History ◽  
Migration Routes ◽  
Effective Population ◽  
Genetic Studies ◽  
Independent Population ◽  
Genome Wide Data ◽  
Population Sizes ◽  
History Of ◽  
Exhaustive Study

ABSTRACTThe study of the genetic structure of different countries within Europe has provided significant insights into their demographic history and their actual stratification. Although France occupies a particular location at the end of the European peninsula and at the crossroads of migration routes, few population genetic studies have been conducted so far with genome-wide data. In this study, we analyzed SNP-chip genetic data from 2 184 individuals born in France who were enrolled in two independent population cohorts. Using FineStructure, six different genetic clusters of individuals were found that were very consistent between the two cohorts. These clusters match extremely well the geography and overlap with historical and linguistic divisions of France. By modeling the relationship between genetics and geography using EEMS software, we were able to detect gene flow barriers that are similar in the two cohorts and corresponds to major French rivers or mountains. Estimations of effective population sizes using IBDNe program also revealed very similar patterns in both cohorts with a rapid increase of effective population sizes over the last 150 generations similar to what was observed in other European countries. A marked bottleneck is also consistently seen in the two datasets starting in the fourteenth century when the Black Death raged in Europe. In conclusion, by performing the first exhaustive study of the genetic structure of France, we fill a gap in the genetic studies in Europe that would be useful to medical geneticists but also historians and archeologists.

scholarly journals Genomic phylogeography of the White-crowned Manakin Pseudopipra pipra (Aves: Pipridae) illuminates a continental-scale radiation out of the Andes

2019 ◽  
Author(s):  
Jacob S. Berv ◽  
Leonardo Campagna ◽  
Teresa J. Feo ◽  
Ivandy Castro-Astor ◽  
Camila C. Ribas ◽  
...  
Keyword(s):  
Gene Flow ◽  
Distinct Species ◽  
Passerine Bird ◽  
Biological Species ◽  
Genetic Connectivity ◽  
Population Isolation ◽  
Continental Scale ◽  
The Andes ◽  
Areas Of Endemism ◽  
History Of

AbstractThe complex landscape history of the Neotropics has generated opportunities for population isolation and subsequent diversification that place this region among the most species-rich in the world. Detailed phylogeographic studies are required to uncover the biogeographic histories of Neotropical taxa, to identify evolutionary correlates of diversity, and to reveal patterns of genetic connectivity, disjunction, and potential differentiation among lineages from different areas of endemism. The White-crowned Manakin (Pseudopipra pipra) is a small suboscine passerine bird that is broadly distributed through the subtropical rainforests of Central America, the lower montane cloud forests of the Andes from Colombia to central Peru, the lowlands of Amazonia and the Guianas, and the Atlantic forest of southeast Brazil. Pseudopipra is currently recognized as a single, polytypic biological species. We studied the effect of the Neotropical landscape on genetic and phenotypic differentiation within this species using genomic data derived from double digest restriction site associated DNA sequencing (ddRAD), and mitochondrial DNA. Most of the genetic breakpoints we identify among populations coincide with physical barriers to gene flow previously associated with avian areas of endemism. The phylogenetic relationships among these populations imply a novel pattern of Andean origination for this group, with subsequent diversification into the Amazonian lowlands. Our analysis of genomic admixture and gene flow establishes a complex history of introgression between some western Amazonian populations. These reticulate processes confound our application of standard concatenated and coalescent phylogenetic methods and raise the question of whether a lineage in the western Napo area of endemism should be considered a hybrid species. Lastly, analysis of variation in vocal and plumage phenotypes in the context of our phylogeny supports the hypothesis that Pseudopipra is a species-complex composed of at least 8, and perhaps up to 17 distinct species which have arisen in the last ∼2.5 Ma.

Weak genetic structuring suggests historically high genetic connectivity among recently fragmented urban populations of the scincid lizard, Ctenotus fallens

2015 ◽  
Vol 63 (4) ◽  
pp. 279 ◽  
Author(s):  
Josef Krawiec ◽  
Siegfried L. Krauss ◽  
Robert A. Davis ◽  
Peter B. S. Spencer
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Population ◽  
Geographic Distance ◽  
Genetic Erosion ◽  
Genetic Connectivity ◽  
Genetic Structuring ◽  
Low Genetic Diversity ◽  
Population Sizes

Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.

scholarly journals Extensive Genetic Connectivity and Historical Persistence Are Features of Two Widespread Tree Species in the Ancient Pilbara Region of Western Australia

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 863
Author(s):  
Heidi M. Nistelberger ◽  
Rachel M. Binks ◽  
Stephen van Leeuwen ◽  
David J. Coates ◽  
Shelley L. McArthur ◽  
...  
Keyword(s):  
Western Australia ◽  
Tree Species ◽  
The Body ◽  
Genetic Connectivity ◽  
Strong Wind ◽  
Cyclonic Activity ◽  
Genetic Structuring ◽  
Long Distance ◽  
Topographic Features ◽  
History Of

Phylogeographic studies can be used as a tool to understand the evolutionary history of a landscape, including the major drivers of species distributions and diversity. Extensive research has been conducted on phylogeographic patterns of species found in northern hemisphere landscapes that were affected by glaciations, yet the body of literature for older, unaffected landscapes is still underrepresented. The Pilbara region of north-western Australia is an ancient and vast landscape that is topographically complex, consisting of plateaus, gorges, valleys, and ranges, and experiences extreme meteorological phenomena including seasonal cyclonic activity. These features are expected to influence patterns of genetic structuring throughout the landscape either by promoting or restricting the movement of pollen and seed. Whilst a growing body of literature exists for the fauna endemic to this region, less is known about the forces shaping the evolution of plant taxa. In this study we investigate the phylogeography of two iconic Pilbara tree species, the Hamersley Bloodwood (Corymbia hamersleyana) and Western Gidgee (Acacia pruinocarpa), by assessing patterns of variation and structure in several chloroplast DNA regions and nuclear microsatellite loci developed for each species. Gene flow was found to be extensive in both taxa and there was evidence of long-distance seed dispersal across the region (pollen to seed ratios of 6.67 and 2.96 for C. hamersleyana and A. pruinocarpa, respectively), which may result from flooding and strong wind gusts associated with extreme cyclonic activity. Both species possessed high levels of cpDNA genetic diversity in comparison to those from formerly glaciated landscapes (C. hamersleyana = 14 haplotypes, A. pruinocarpa = 37 haplotypes) and showed evidence of deep lineage diversification occurring from the late Miocene, a time of intensifying aridity in this landscape that appears to be a critical driver of evolution in Pilbara taxa. In contrast to another study, we did not find evidence for topographic features acting as refugia for the widely sampled C. hamersleyana.

scholarly journals Living on the edge: how philopatry maintains adaptive potential

2013 ◽  
Vol 280 (1763) ◽  
pp. 20130305 ◽  
Author(s):  
Victor A. Stiebens ◽  
Sonia E. Merino ◽  
Christian Roder ◽  
Frédéric J. J. Chain ◽  
Patricia L. M. Lee ◽  
...  
Keyword(s):  
Gene Flow ◽  
Positive Association ◽  
Sea Turtle ◽  
Genetic Connectivity ◽  
Small Scale ◽  
Adaptive Potential ◽  
Loggerhead Sea Turtle ◽  
Local Adaptations ◽  
Population Sizes ◽  
Genomic Regions

Without genetic variation, species cannot cope with changing environments, and evolution does not proceed. In endangered species, adaptive potential may be eroded by decreased population sizes and processes that further reduce gene flow such as philopatry and local adaptations. Here, we focused on the philopatric and endangered loggerhead sea turtle ( Caretta caretta ) nesting in Cape Verde as a model system to investigate the link between adaptive potential and philopatry. We produced a dataset of three complementary genomic regions to investigate female philopatric behaviour (mitochondrial DNA), male-mediated gene flow (microsatellites) and adaptive potential (major histocompatibility complex, MHC). Results revealed genetically distinct nesting colonies, indicating remarkably small-scale philopatric behaviour of females. Furthermore, these colonies also harboured local pools of MHC alleles, especially at the margins of the population's distribution, which are therefore important reserves of additional diversity for the population. Meanwhile, directional male-mediated gene flow from the margins of distribution sustains the adaptive potential for the entire rookery. We therefore present the first evidence for a positive association between philopatry and locally adapted genomic regions. Contrary to expectation, we propose that philopatry conserves a high adaptive potential at the margins of a distribution, while asymmetric gene flow maintains genetic connectivity with the rest of the population.

scholarly journals In with the Old, in with the New: The Promiscuity of the Duplication Process Engenders Diverse Pathways for Novel Gene Creation

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Vaishali Katju
Keyword(s):  
Gene Duplication ◽  
Population Size ◽  
Population Genetic ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Dna And Rna ◽  
Duplication Events ◽  
History Of ◽  
Theoretical Population ◽  
Novel Exon

The gene duplication process has exhibited far greater promiscuity in the creation of paralogs with novel exon-intron structures than anticipated even by Ohno. In this paper I explore the history of the field, from the neo-Darwinian synthesis through Ohno’s formulation of the canonical model for the evolution of gene duplicates and culminating in the present genomic era. I delineate the major tenets of Ohno’s model and discuss its failure to encapsulate the full complexity of the duplication process as revealed in the era of genomics. I discuss the diverse classes of paralogs originating from both DNA- and RNA-mediated duplication events and their evolutionary potential for assuming radically altered functions, as well as the degree to which they can function unconstrained from the pressure of gene conversion. Lastly, I explore theoretical population-genetic considerations of how the effective population size (Ne) of a species may influence the probability of emergence of genes with radically altered functions.

scholarly journals By Animal, Water, or Wind: Can Dispersal Mode Predict Genetic Connectivity in Riverine Plant Species?

2021 ◽  
Vol 12 ◽  
Author(s):  
Alison G. Nazareno ◽  
L. Lacey Knowles ◽  
Christopher W. Dick ◽  
Lúcia G. Lohmann
Keyword(s):  
Gene Flow ◽  
Seed Dispersal ◽  
Plant Species ◽  
Amazon Basin ◽  
Geographic Distance ◽  
Genetic Connectivity ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Deforestation Rates ◽  
History Of

Seed dispersal is crucial to gene flow among plant populations. Although the effects of geographic distance and barriers to gene flow are well studied in many systems, it is unclear how seed dispersal mediates gene flow in conjunction with interacting effects of geographic distance and barriers. To test whether distinct seed dispersal modes (i.e., hydrochory, anemochory, and zoochory) have a consistent effect on the level of genetic connectivity (i.e., gene flow) among populations of riverine plant species, we used unlinked single-nucleotide polymorphisms (SNPs) for eight co-distributed plant species sampled across the Rio Branco, a putative biogeographic barrier in the Amazon basin. We found that animal-dispersed plant species exhibited higher levels of genetic diversity and lack of inbreeding as a result of the stronger genetic connectivity than plant species whose seeds are dispersed by water or wind. Interestingly, our results also indicated that the Rio Branco facilitates gene dispersal for all plant species analyzed, irrespective of their mode of dispersal. Even at a small spatial scale, our findings suggest that ecology rather than geography play a key role in shaping the evolutionary history of plants in the Amazon basin. These results may help improve conservation and management policies in Amazonian riparian forests, where degradation and deforestation rates are high.

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