scholarly journals Gene flow relates to evolutionary divergence among populations at the range margin

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10036 ◽  
Author(s):  
Peter Kaňuch ◽  
Berrit Kiehl ◽  
Anna Cassel-Lundhagen ◽  
Ane T. Laugen ◽  
Matthew Low ◽  
...  
Keyword(s):  
Gene Flow ◽  
Continuous Distribution ◽  
Morphological Differentiation ◽  
Environmental Drivers ◽  
Restricted Gene Flow ◽  
Evolutionary Divergence ◽  
Clinal Variation ◽  
Isolated Populations ◽  
Phenotypic Effect ◽  
Local Adaptations

Background Morphological differentiation between populations resulting from local adaptations to environmental conditions is likely to be more pronounced in populations with increasing genetic isolation. In a previous study a positive clinal variation in body size was observed in isolated Roesel’s bush-cricket, Metrioptera roeselii, populations, but were absent from populations within a continuous distribution at the same latitudinal range. This observational study inferred that there was a phenotypic effect of gene flow on climate-induced selection in this species. Methods To disentangle genetic versus environmental drivers of population differences in morphology, we measured the size of four different body traits in wild-caught individuals from the two most distinct latitudinally-matched pairs of populations occurring at about 60°N latitude in northern Europe, characterised by either restricted or continuous gene flow, and corresponding individuals raised under laboratory conditions. Results Individuals that originated from the genetically isolated populations were always bigger (femur, pronotum and genital appendages) when compared to individuals from latitudinally-matched areas characterised by continuous gene flow between populations. The magnitude of this effect was similar for wild-caught and laboratory-reared individuals. We found that previously observed size cline variation in both male and female crickets was likely to be the result of local genetic adaptation rather than phenotypic plasticity. Conclusions This strongly suggests that restricted gene flow is of major importance for frequencies of alleles that participate in climate-induced selection acting to favour larger phenotypes in isolated populations towards colder latitudes.

Morphological variability of the Lataste's viper (Vipera latastei) and the Atlas dwarf viper (Vipera monticola): patterns of biogeographical distribution and taxonomy

2006 ◽  
Vol 27 (2) ◽  
pp. 219-240 ◽  
Author(s):  
Xavier Parellada ◽  
Soumia Fahd ◽  
Xavier Santos ◽  
José Brito ◽  
Gustavo Llorente ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Function Analysis ◽  
Morphological Variability ◽  
Morphological Differentiation ◽  
Clinal Variation ◽  
Geographic Variability ◽  
Isolated Populations ◽  
High Atlas ◽  
Morphological Studies ◽  
Biogeographical Distribution

AbstractThe Lataste's viper Vipera latastei is a medium-sized viper distributed throughout almost the entire Iberian Peninsula and north-west of Africa. Former morphological studies noted the existence of two subspecies, V. l. gaditana and V. l. latastei, as well as a full species, V. monticola, in the High Atlas, corresponding to the prior overall range described for V. latastei. However, some results remained unclear in these former studies, e.g. the specific status of the Medium Atlas populations, the intra-subspecific differences in V. l. gaditana and, the true status of some isolated populations of the northern range. For this reason, 45 morphological characters were analysed in 672 preserved specimens covering the entire range. Categorical Principal Components Analysis (CATPCA) and Discriminant Function Analysis (DFA) were used to assess geographic variability, treating specimens individually or assigning them a priori to groups, respectively. Geographic groups were established according to the origin of specimens in isolated areas of mountain chains. As the percentage of correct assignment was low in DFA, initial groups were combined to maximize the percentage. The results from the multivariate analysis suggest morphological differentiation between populations. Some variables accounted for geographic variability: e.g. rows of dorsal scales at mid-body are taxonomically stable and clearly separate the African populations; and number of ventral scales showed a clinal variation from 126 to 143 ventrals in extreme populations. The three African groups manifested clear morphological differences, and especially specimens from the High Atlas (V. monticola) and Alger. On the contrary, a large number of initial Iberian groups were merged because of the low scores in the correct classification. The final groups showed a vast central area with low morphological differentiation as well as isolated populations in the NW, NE and SW Iberian Peninsula. This conclusion matches well with allopatric speciation processes during the Quaternary ice ages, which contributed to the contraction/expansion of range, isolation events, and peripheral population refugia. Morphological differentiation in external characters of V. latastei exhibited similar results with respect to V. aspis and V. ammodytes, the vipers occupying other southern European peninsulas. Molecular markers will contribute to elucidate the relationships between V. latastei populations and the history of colonisation across the Strait of Gibraltar.

A comparison of population differentiation in two shore crab species with contrasting distribution along the Portuguese coast, using two morphological methodologies

2009 ◽  
Vol 60 (8) ◽  
pp. 833 ◽  
Author(s):  
Inês C. Silva ◽  
Stephen J. Hawkins ◽  
José Paula
Keyword(s):  
Population Differentiation ◽  
Carcinus Maenas ◽  
Continuous Distribution ◽  
Morphological Differentiation ◽  
Shore Crab ◽  
Clinal Variation ◽  
Rocky Shores ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Variation Explained

Along the Portuguese coast, Pachygrapsus marmoratus has a continuous distribution on rocky shores. In contrast, Carcinus maenas has a discontinuous distribution, inhabiting estuaries. Surveys along a coastal latitudinal gradient were made to assess the effect of the distribution pattern on population differentiation of these two species. Population differentiation was studied using two different morphometric methodologies: linear-based morphometrics and landmark-based morphometrics. The linear-based analysis revealed no significant morphological differentiation among the eleven P. marmoratus populations. Landmark-based analysis showed that the northern and central populations were more similar in shape than the southern populations. Nevertheless, there was still some overlap in shape that could be due to the continuous distribution of P. marmoratus along the coast, promoting population panmixia. In C. maenas, both morphometric techniques revealed the existence of morphological differentiation among populations. This shape differentiation showed a clinal variation, explained by a higher degree of isolation of populations that might be due to limited larval flow between them. Environmental factors may also play an important role in causing variation of shape. Landmark-based morphometrics yielded stronger evidence of morphological differences among forms than a linear approach, suggesting that this method may be more suitable for analysis of body shape.

scholarly journals Strong Gene Flow Undermines Local Adaptations in a Host Parasite System

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 585
Author(s):  
Perttu Seppä ◽  
Mariaelena Bonelli ◽  
Simon Dupont ◽  
Sanja Maria Hakala ◽  
Anne-Geneviève Bagnères ◽  
...  
Keyword(s):  
Gene Flow ◽  
Defense Mechanisms ◽  
Spatial Genetic Structure ◽  
Social Wasp ◽  
Structured Populations ◽  
Social Parasite ◽  
Restricted Gene Flow ◽  
Dna Microsatellites ◽  
Geographic Mosaic ◽  
Local Adaptations

The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve.

scholarly journals Dispersal and local persistence shape the genetic structure of a widespread Neotropical plant species with a patchy distribution

2019 ◽  
Vol 124 (3) ◽  
pp. 499-512 ◽  
Author(s):  
Bárbara Simões Santos Leal ◽  
Vanessa Araujo Graciano ◽  
Cleber Juliano Neves Chaves ◽  
Luis Alberto Pillaca Huacre ◽  
Myriam Heuertz ◽  
...  
Keyword(s):  
Gene Flow ◽  
Evolutionary Dynamics ◽  
Nuclear Dna ◽  
Sequence Data ◽  
Molecular Data ◽  
Minor Role ◽  
Restricted Gene Flow ◽  
Isolated Populations ◽  
Distribution Models ◽  
Patchy Distribution

Abstract Background and Aims Isolated populations constitute an ideal laboratory to study the consequences of intraspecific divergence, because intrinsic incompatibilities are more likely to accumulate under reduced gene flow. Here, we use a widespread bromeliad with a patchy distribution, Pitcairnia lanuginosa, as a model to infer processes driving Neotropical diversification and, thus, to improve our understanding of the origin and evolutionary dynamics of biodiversity in this highly speciose region. Methods We assessed the timing of lineage divergence, genetic structural patterns and historical demography of P. lanuginosa, based on microsatellites, and plastid and nuclear sequence data sets using coalescent analyses and an Approximate Bayesian Computation framework. Additionally, we used species distribution models (SDMs) to independently estimate potential changes in habitat suitability. Key Results Despite morphological uniformity, plastid and nuclear DNA data revealed two distinct P. lanuginosa lineages that probably diverged through dispersal from the Cerrado to the Central Andean Yungas, following the final uplift of the Andes, and passed through long-term isolation with no evidence of migration. Microsatellite data indicate low genetic diversity and high levels of inbreeding within populations, and restricted gene flow among populations, which are likely to be a consequence of bottlenecks (or founder events), and high selfing rates promoting population persistence in isolation. SDMs showed a slight expansion of the suitable range for P. lanuginosa lineages during the Last Glacial Maximum, although molecular data revealed a signature of older divergence. Pleistocene climatic oscillations thus seem to have played only a minor role in the diversification of P. lanuginosa, which probably persisted through adverse conditions in riparian forests. Conclusions Our results imply drift as a major force shaping the evolution of P. lanuginosa, and suggest that dispersal events have a prominent role in connecting Neotropical open and forest biomes.

Are there populations suffering genetic erosion that would benefit from augmented gene flow?

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Erosion ◽  
Genetic Rescue ◽  
Isolated Populations

Having identified small geographically and genetically isolated populations, we need to determine whether they are suffering genetic erosion, and if so, whether there are any other populations to which they could be crossed. We should next ask whether crossing is expected to be harmful or beneficial, and if beneficial, whether the benefits would be large enough to justify a genetic rescue attempt. Here, we address these questions based on the principles established in the preceding chapters.

Segregation and speciation in the Neogene planktonic foraminiferal clade Globoconella

Paleobiology ◽  
1999 ◽  
Vol 25 (3) ◽  
pp. 383-395 ◽  
Author(s):  
Cynthia E. Schneider ◽  
James P. Kennett
Keyword(s):  
Morphological Evolution ◽  
Evolutionary Divergence ◽  
Clinal Variation ◽  
Near Surface ◽  
Surface Warming ◽  
Isotopic Analyses ◽  
Oxygen Isotopic ◽  
Morphological Differences ◽  
Middle Pliocene ◽  
Water Depths

The origin of the Neogene planktonic foraminifer Globorotalia (Globoconella) pliozea in the subtropical southwest Pacific has been attributed to its isolation resulting from intensification of the Subtropical Divergence (Tasman Front). Oxygen isotopic analyses suggest that, although the Subtropical Divergence may have played a role, the evolution of Gr. (G.) pliozea was facilitated by depth segregation of Gr. (G.) conomiozea morphotypes (low and high conical) during an interval of near-surface warming and increasing thermal gradient. Oxygen isotopic analyses suggest that low conical morphotypes of Gr. (G.) conomiozea inhabited greater depths than high conical morphotypes. Low conical forms of Gr. (G.) conomiozea are considered ancestral to the low conical species, Gr. (G.) pliozea. Oxygen isotopes indicate that Gr. (G.) pliozea inhabited greater depths than its ancestor, Gr. (G.) conomiozea.These data are consistent with depth-parapatric and depth-allopatric models, but not with a sympatric model of speciation. In the allopatric model, reproduction at different water depths acts as a barrier between morphotypes. In the parapatric model, clinal variation along a depth gradient acts as a barrier between morphotypes living at the limits of the gradient. Depth segregation in both models results in genetic isolation and evolutionary divergence. Our data support a correlation between morphological evolution and habitat changes in the Globoconella clade, implying separation of populations as a driving force for morphological evolution.Ecological segregation of morphotypes and species may be related to morphology (height of the conical angle), based on the data from Gr. (G.) conomiozea and Gr. (G.) pliozea. However, morphological differences alone do not necessarily produce depth differences. Large morphological differences between Gr. (G.) pliozea and closely related Gr. (G.) puncticulata did not result in isotopic and therefore depth differences between these species. These species coexisted at the same water depths for nearly 1 m.y. Thus, it is unlikely that the extinction of Gr. (G.) pliozea in the middle Pliocene resulted from competition with Gr. (G.) puncticulata, as previously suggested.

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.

scholarly journals Adaptive Divergence under Gene Flow along an Environmental Gradient in Two Coexisting Stickleback Species

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 435
Author(s):  
Thijs M. P. Bal ◽  
Alejandro Llanos-Garrido ◽  
Anurag Chaturvedi ◽  
Io Verdonck ◽  
Bart Hellemans ◽  
...  
Keyword(s):  
Gene Flow ◽  
Brackish Water ◽  
Environmental Gradient ◽  
Spatial Scales ◽  
Morphological Differentiation ◽  
Genotyping By Sequencing ◽  
Adaptive Divergence ◽  
Linkage Groups ◽  
Closely Related Species ◽  
Genomic Patterns

There is a general and solid theoretical framework to explain how the interplay between natural selection and gene flow affects local adaptation. Yet, to what extent coexisting closely related species evolve collectively or show distinctive evolutionary responses remains a fundamental question. To address this, we studied the population genetic structure and morphological differentiation of sympatric three-spined and nine-spined stickleback. We conducted genotyping-by-sequencing and morphological trait characterisation using 24 individuals of each species from four lowland brackish water (LBW), four lowland freshwater (LFW) and three upland freshwater (UFW) sites in Belgium and the Netherlands. This combination of sites allowed us to contrast populations from isolated but environmentally similar locations (LFW vs. UFW), isolated but environmentally heterogeneous locations (LBW vs. UFW), and well-connected but environmentally heterogenous locations (LBW vs. LFW). Overall, both species showed comparable levels of genetic diversity and neutral genetic differentiation. However, for all three spatial scales, signatures of morphological and genomic adaptive divergence were substantially stronger among populations of the three-spined stickleback than among populations of the nine-spined stickleback. Furthermore, most outlier SNPs in the two species were associated with local freshwater sites. The few outlier SNPs that were associated with the split between brackish water and freshwater populations were located on one linkage group in three-spined stickleback and two linkage groups in nine-spined stickleback. We conclude that while both species show congruent evolutionary and genomic patterns of divergent selection, both species differ in the magnitude of their response to selection regardless of the geographical and environmental context.

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