scholarly journals Environmental differences explain subtle yet detectable genetic structure in a widespread pollinator

2021 ◽  
Author(s):  
Marcel Glück ◽  
Julia C. Geue ◽  
Henri A. Thomassen
Keyword(s):  
Genetic Structure ◽  
Geographic Distance ◽  
Natural Populations ◽  
Environmental Data ◽  
Genetic Connectivity ◽  
Population Divergence ◽  
Bumble Bee ◽  
Bayesian Clustering ◽  
Holistic Understanding ◽  
Isolation By Environment

Background: The environment is a strong driver of genetic structure in many natural populations, yet often neglected in population genetic studies. This may be a particular problem in vagile species, where subtle structure cannot be explained by limitations to dispersal. These species might falsely be considered panmictic and hence potentially mismanaged. Here we analysed the genetic structure in an economically important and widespread pollinator, the buff-tailed bumble bee (Bombus terrestris), which is considered to be quasi-panmictic at mainland continental scales. We first quantified population structure in Romania and Bulgaria with spatially implicit Fst and Bayesian clustering analyses. We then incorporated environmental information to infer the influence of the permeability of the habitat matrix between populations (resistance distances) as well as environmental differences among sites in explaining population divergence. Results: Genetic structure of the buff-tailed bumble bee was subtle and not detected by Bayesian clustering. As expected, geographic distance and habitat permeability were not informative in explaining the spatial pattern of genetic divergence. Yet, environmental variables related to temperature, vegetation and topography were highly informative, explaining between 33 and 39% of the genetic variation observed. Conclusions: Where in the past spatially implicit approaches had repeatedly failed, incorporating environmental data proved to be highly beneficial in detecting and unravelling the drivers of genetic structure in this vagile and opportunistic species. Indeed, structure followed a pattern of isolation by environment, where the establishment of dispersers is limited by environmental differences among populations, resulting in the disruption of genetic connectivity and the divergence of populations through genetic drift and divergent natural selection. With this work, we highlight the potential of incorporating environmental differences among population locations to complement the more traditional approach of isolation by geographic distance, in order to obtain a holistic understanding of the processes driving structure in natural populations.

scholarly journals Genetic structure is stronger across human-impacted habitats than among islands in the coralPorites lobata

2019 ◽  
Author(s):  
Kaho H. Tisthammer ◽  
Zac H. Forsman ◽  
Robert J. Toonen ◽  
Robert H. Richmond
Keyword(s):  
Genetic Structure ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
High Stress ◽  
Disruptive Selection ◽  
Single Location ◽  
Isolation By Environment ◽  
Genetic Patterns ◽  
Significant Genetic Structure ◽  
Contrasting Habitats

ABSTRACTWe examined genetic structure in the lobe coralPorites lobataamong pairs of highly variable and high-stress nearshore sites and adjacent less variable and less impacted offshore sites on the islands of Oʻahu and Maui, Hawai‘i. Using an analysis of molecular variance framework, we tested whether populations were more structured by geographic distance or environmental extremes. The genetic patterns we observed followed isolation by environment, where nearshore and adjacent offshore populations showed significant genetic structure at both locations (AMOVAFST= 0.04 ∼ 0.19,P< 0.001), but no significant isolation by distance between islands. In contrast, a third site with a less impacted nearshore site showed no significant structure. Strikingly, corals from the two impacted nearshore sites on different islands over 100km apart with similar environmentally stressful conditions were genetically closer (FST∼ 0, P = 0.733) than those within a single location less than 2 km apart (FST= 0.041∼0.079, P < 0.01). Our results suggest that ecological boundaries appear to play a strong role in forming genetic structure in the coastal environment, and that genetic divergence in the absence of geographical barriers to gene flow may be explained by disruptive selection across contrasting habitats.

scholarly journals Genetic variation and cryptic lineage diversity of the Nigerian red-headed rock agama Agama agama associate with eco-geographic zones

2019 ◽  
Vol 65 (6) ◽  
pp. 713-724 ◽  
Author(s):  
Lotanna M Nneji ◽  
Adeniyi C Adeola ◽  
Fang Yan ◽  
Agboola O Okeyoyin ◽  
Ojo C Oladipo ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Geographic Distance ◽  
Climatic Conditions ◽  
Population Divergence ◽  
Geographic Isolation ◽  
Genetic Structuring ◽  
Derived Savanna ◽  
Wide Range ◽  
Conservation Actions ◽  
The Impact

AbstractNigeria is an Afrotropical region with considerable ecological heterogeneity and levels of biotic endemism. Among its vertebrate fauna, reptiles have broad distributions, thus, they constitute a compelling system for assessing the impact of ecological variation and geographic isolation on species diversification. The red-headed rock agama, Agama agama, lives in a wide range of habitats and, thus, it may show genetic structuring and diversification. Herein, we tested the hypothesis that ecology affects its genetic structure and population divergence. Bayesian inference phylogenetic analysis of a mitochondrial DNA (mtDNA) gene recovered four well-supported matrilines with strong evidence of genetic structuring consistent with eco-geographic regions. Genetic differences among populations based on the mtDNA also correlated with geographic distance. The ecological niche model for the matrilines had a good fit and robust performance. Population divergence along the environmental axes was associated with climatic conditions, and temperature ranked highest among all environmental variables for forest specialists, while precipitation ranked highest for the forest/derived savanna, and savanna specialists. Our results cannot reject the hypothesis that niche conservatism promotes geographic isolation of the western populations of Nigerian A. agama. Thus, ecological gradients and geographic isolation impact the genetic structure and population divergence of the lizards. This species might be facing threats due to recent habitat fragmentation, especially in western Nigeria. Conservation actions appear necessary.

scholarly journals Genetic Structure of Natural Populations of Wild Sunflowers (Helianthus annuus L.) in Australia

1986 ◽  
Vol 39 (3) ◽  
pp. 255 ◽  
Author(s):  
PJ Dry ◽  
JJ Burdon
Keyword(s):  
Genetic Structure ◽  
Gene Diversity ◽  
New South ◽  
Geographic Distance ◽  
Natural Populations ◽  
Wild Populations ◽  
South Wales ◽  
Fixation Indices ◽  
O 19 ◽  
Isozyme Diversity

The genetic structure of 11 wild populations of H. annuus occurring in New South Wales and Queensland was determined by isozyme analysis. Considerable isozyme diversity was found among loci within and between populations, with three to five alleles being identified at each of 10 loci. Mean levels of heterozygosity ranged from o� 19 to O� 38 and gene diversity values from 0�29 to O� 52. In all populations Wright's fixation indices were positive (0�09-0� 51) suggesting a degree of inbreeding. Differences in the level of genetic differentiation between populations were not correlated with geographic distance. Indeed, notable genetic diversity was detected between six sites occurring within a 2-km radius of Gunnedah, N.S.W., where the genetic distance relationships were D = 0�13 � 0'08, the same as those between popUlations throughout the region.

scholarly journals Genetic Structure in Populations of Euterpe precatoria Mart. in the Brazilian Amazon

2021 ◽  
Vol 8 ◽  
Author(s):  
Santiago Linorio Ferreyra Ramos ◽  
Gabriel Dequigiovanni ◽  
Maria Teresa Gomes Lopes ◽  
Ananda Virginia de Aguiar ◽  
Ricardo Lopes ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Bayesian Analysis ◽  
Management Strategies ◽  
Geographic Distance ◽  
Natural Populations ◽  
Population Level ◽  
Brazilian Amazon ◽  
The State ◽  
Fixation Index ◽  
Palm Tree

Euterpe precatoria is a palm tree belonging to the Arecaceae family, occurring in Western and Central Brazilian Amazonia. Its fruit, which is very appreciated in the Amazon region, produces pulp that is consumed in fresh form. Its production is carried out almost exclusively by extractive farmers. In order to establish adequate strategies to sustain this genetic resource, we need knowledge about the diversity and genetic structure in natural populations. This study aimed to evaluate the influence of geographic distance on genetic structure in the main extractive populations of E. precatoria in the Brazilian Amazon. Leaves from 377 plants were collected in 19 populations located in 16 municipalities in the State of Amazonas and three in the State of Rondônia. Twelve microsatellite loci were used to genotype the plants. The diversity and genetic structure among populations were estimated. The average number of alleles per locus was 5.97. The observed heterozygosity means (HO) were higher than expected (HE) at the population level (HO = 0.72, HE = 0.66) and fixation index (f = -0.100) was negative. The FST value (0.1820) and the AMOVA results (Φ = 0.1796) showed population structure. The populations were clustered into three groups (K = 3) in the Bayesian analysis. The Discriminant Analysis of Principal Components (DAPC) confirmed eight clusters, with the populations close to those identified by the Bayesian analysis. The geographic differentiation was confirmed by the groupings obtained in the Structure analysis and the DACP function. Information related to phenotypic, genetic and environmental characterization of populations is important to guide conservation and management strategies and the formulation of public species management policies in Amazonia.

scholarly journals Genetic structure of natural populations of Cryptocarya moschata Nees (Lauraceae) from southeastern Brazilian Atlantic rain forest

2004 ◽  
Vol 4 (1) ◽  
pp. 01-16 ◽  
Author(s):  
Pedro Luís Rodrigues de Moraes ◽  
Maria Teresa Vitral de Carvalho Derbyshire
Keyword(s):  
Genetic Structure ◽  
Rain Forest ◽  
Evolutionary Dynamics ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
Natural Populations ◽  
Conservation Strategies ◽  
Atlantic Rain Forest ◽  
Effective Population ◽  
Allozyme Loci

This study was accomplished on a more comprehensive basis to evaluate previous questions that were raised from a preliminary article about the genetic structure of Cryptocarya moschata populations. Thus, through the analysis of 40 polymorphic allozyme loci, allele frequencies were estimated from 335 individuals of 11 natural populations of C. moschata from six hydrographic basins of São Paulo state and Serra da Estrela, Rio de Janeiro, Brazil. Estimates of Wright's F statistics were done through the analysis of variance, presenting average values of <img border=0 width=32 height=32 id="_x0000_i1026" src="../../../../../../img/revistas/bn/v4n1/img/a04car(f).jpg" align=absmiddle > or = 0.352, <img border=0 width=32 height=32 id="_x0000_i1027" src="../../../../../../img/revistas/bn/v4n1/img/a04car(0p).jpg" align=absmiddle > or = 0.285 and <img border=0 width=32 height=32 id="_x0000_i1028" src="../../../../../../img/revistas/bn/v4n1/img/a04car(f2).jpg" align=absmiddle > or = 0.097. These results indicated that individuals within populations must be panmitic, and that the diversity among populations is fairly high, being superior to what would be expected for groups of plants having a full-sib family structure. From estimates of <img border=0 width=32 height=32 id="_x0000_i1029" src="../../../../../../img/revistas/bn/v4n1/img/a04car(0p).jpg" align=absmiddle>obtained for populations taken two at a time, the model of isolation by distance was tested; data did not fit the model, showing that <img border=0 width=32 height=32 id="_x0000_i1030" src="../../../../../../img/revistas/bn/v4n1/img/a04car(0p).jpg" align=absmiddle>did not increase by the respective increasing of the geographic distance. The estimated gene flow of 0.55 migrants per generation corroborated the pronounced populational differentiation, indicating that drift effects should be more important than the selection ones. The effective population sizes found from the sampled populations showed that there was an adequate genetic representativeness of the samples for those with relatively low values of <img border=0 width=32 height=32 id="_x0000_i1031" src="../../../../../../img/revistas/bn/v4n1/img/a04car(f2).jpg" align=absmiddle>. Though, under a metapopulation context, the effective population size was 17.07 individuals, indicating that sampling performed for the species corresponded to 88.44% of the maximum effective size obtained from 11 populations with a <img border=0 width=32 height=32 id="_x0000_i1032" src="../../../../../../img/revistas/bn/v4n1/img/a04car(0p).jpg" align=absmiddle>of 0.285, equivalent to only 5.09% individuals for the total sampled. Management and conservation strategies aimed at preserving high intrapopulation genetic variation in C. moschata would imply in the maintenance of populations with great number of individuals. Moreover, for the preservation of the species as a whole, the maintenance of many such populations would be mandatorily recommended, which denotes that the conservation of large areas of Atlantic rain forest should be necessary to hold its evolutionary dynamics.

scholarly journals Genetic structure is stronger across human-impacted habitats than among islands in the coral Porites lobata

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8550 ◽  
Author(s):  
Kaho H. Tisthammer ◽  
Zac H. Forsman ◽  
Robert J. Toonen ◽  
Robert H. Richmond
Keyword(s):  
Genetic Structure ◽  
Human Impacts ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
High Stress ◽  
Single Location ◽  
Isolation By Environment ◽  
Porites Lobata ◽  
Significant Genetic Structure ◽  
Contrasting Habitats

We examined genetic structure in the lobe coral Porites lobata among pairs of highly variable and high-stress nearshore sites and adjacent less variable and less impacted offshore sites on the islands of Oahu and Maui, Hawaii. Using an analysis of molecular variance framework, we tested whether populations were more structured by geographic distance or environmental extremes. The genetic patterns we observed followed isolation by environment, where nearshore and adjacent offshore populations showed significant genetic structure at both locations (AMOVA FST = 0.04∼0.19, P < 0.001), but no significant isolation by distance between islands. Strikingly, corals from the two nearshore sites with higher levels of environmental stressors on different islands over 100 km apart with similar environmentally stressful conditions were genetically closer (FST = 0.0, P = 0.73) than those within a single location less than 2 km apart (FST = 0.04∼0.08, P < 0.01). In contrast, a third site with a less impacted nearshore site (i.e., less pronounced environmental gradient) showed no significant structure from the offshore comparison. Our results show much stronger support for environment than distance separating these populations. Our finding suggests that ecological boundaries from human impacts may play a role in forming genetic structure in the coastal environment, and that genetic divergence in the absence of geographical barriers to gene flow might be explained by selective pressure across contrasting habitats.

scholarly journals Spatio-temporal genetic structure of the rodent Calomys venustus in linear, fragmented habitats

2015 ◽  
Vol 97 (2) ◽  
pp. 424-435 ◽  
Author(s):  
Marina B. Chiappero ◽  
Lucía V. Sommaro ◽  
José W. Priotto ◽  
María Paula Wiernes ◽  
Andrea R. Steinmann ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Genetic Variability ◽  
Spatial Genetic Structure ◽  
Geographic Distance ◽  
Sampling Period ◽  
Causal Modeling ◽  
Genetic Connectivity ◽  
Small Scale ◽  
Linear Habitats ◽  
Spatio Temporal

Abstract Studies about habitat fragmentation, in terms of how it affects gene flow and genetic variability, have traditionally been conducted on island-like systems in which the remaining habitats form patches embedded in a matrix. However, in agroecosystems, remaining habitats usually form linear strips along fence lines, roads, and water courses (“border” habitats). We used the rodent Calomys venustus , a species inhabiting borders in central Argentina agroecosystems, as a model to address how genetic variability is structured in linear habitats. A total of 359 rodents were captured seasonally from spring 2005 to winter 2006. Genetic variability at microsatellite loci was uniformly high, despite significant variation in population size during the sampling period. Genetic differentiation, spatial autocorrelation, and causal modeling analyses suggested that dispersion patterns in this species depend mainly on geographic distance, with unfavorable habitat like dirt roads and crop fields posing only weak (or no) resistance to dispersal. Small-scale spatial genetic structure was related to different space use patterns by females and males. Our results showed that, although greatly reduced in area, border habitats can support stable populations of species without loss of either variability or genetic connectivity. Los efectos de la fragmentación del hábitat sobre el flujo génico y la variabilidad genética, se han estudiado tradicionalmente en sistemas tipo islas, en los cuales los hábitats remanentes forman parches embebidos en una matriz. Sin embargo, en los agroecosistemas, éstos suelen tener forma lineal a lo largo de alambrados, caminos y corrientes de agua (hábitats de “borde”). En este trabajo, utilizamos al roedor Calomys venustus , especie típica de ambientes de borde en los agroecosistemas del centro de Argentina, como modelo para estudiar cómo la variabilidad genética se estructura en hábitats lineales. Un total de 359 roedores se capturaron estacionalmente desde la primavera de 2005 hasta el invierno de 2006. La variabilidad genética encontrada en loci de microsatélites fue siempre alta, a pesar de una variación significativa del tamaño poblacional a lo largo del período de estudio. Los análisis de diferenciación genética, autocorrelación genética espacial y modelado causal sugieren que los patrones de dispersión en esta especie dependen principalmente de la distancia geográfica, y que los hábitats desfavorables como caminos de tierra y campos de cultivo representan una barrera débil (o nula) para la dispersión. La estructura genética a escala pequeña estuvo relacionada al diferente uso del espacio por parte de machos y hembras. Nuestros resultados mostraron que a pesar de tener un área reducida, los hábitat de bordes pueden mantener poblaciones estables sin pérdida de variabilidad genética o reducción del flujo génico.

scholarly journals Highly restricted dispersal in habitat-forming seaweed may impede natural recovery of disturbed populations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Florentine Riquet ◽  
Christiane-Arnilda De Kuyper ◽  
Cécile Fauvelot ◽  
Laura Airoldi ◽  
Serge Planes ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Spatial Scales ◽  
Mediterranean Ecosystems ◽  
Dispersal Distance ◽  
Genetic Connectivity ◽  
Restricted Gene Flow ◽  
Isolated Populations ◽  
Natural Recovery ◽  
Limited Dispersal ◽  
Ecological Importance

AbstractCystoseira sensu lato (Class Phaeophyceae, Order Fucales, Family Sargassaceae) forests play a central role in marine Mediterranean ecosystems. Over the last decades, Cystoseira s.l. suffered from a severe loss as a result of multiple anthropogenic stressors. In particular, Gongolaria barbata has faced multiple human-induced threats, and, despite its ecological importance in structuring rocky communities and hosting a large number of species, the natural recovery of G. barbata depleted populations is uncertain. Here, we used nine microsatellite loci specifically developed for G. barbata to assess the genetic diversity of this species and its genetic connectivity among fifteen sites located in the Ionian, the Adriatic and the Black Seas. In line with strong and significant heterozygosity deficiencies across loci, likely explained by Wahlund effect, high genetic structure was observed among the three seas (ENA corrected FST = 0.355, IC = [0.283, 0.440]), with an estimated dispersal distance per generation smaller than 600 m, both in the Adriatic and Black Sea. This strong genetic structure likely results from restricted gene flow driven by geographic distances and limited dispersal abilities, along with genetic drift within isolated populations. The presence of genetically disconnected populations at small spatial scales (< 10 km) has important implications for the identification of relevant conservation and management measures for G. barbata: each population should be considered as separated evolutionary units with dedicated conservation efforts.

Significant genetic differences among Heterodera schachtii populations within and among sugar beet production areas

Nematology ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Rasha Haj Nuaima ◽  
Johannes Roeb ◽  
Johannes Hallmann ◽  
Matthias Daub ◽  
Holger Heuer
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Spatial Scales ◽  
Geographic Distance ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Neutral Genetic Variation ◽  
Production Areas

Summary Characterising the non-neutral genetic variation within and among populations of plant-parasitic nematodes is essential to determine factors shaping the population genetic structure. This study describes the genetic variation of the parasitism gene vap1 within and among geographic populations of the beet cyst nematode Heterodera schachtii. Forty populations of H. schachtii were sampled at four spatial scales: 695 km, 49 km, 3.1 km and 0.24 km. DGGE fingerprinting showed significant differences in vap1 patterns among populations. High similarity of vap1 patterns appeared between geographically close populations, and occasionally among distant populations. Analysis of spatially sampled populations within fields revealed an effect of tillage direction on the vap1 similarity for two of four studied fields. Overall, geographic distance and similarity of vap1 patterns of H. schachtii populations were negatively correlated. In conclusion, the population genetic structure was shaped by the interplay between the genetic adaptation and the passive transport of this nematode.

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