Experimental Hybridization Studies Suggest That Pleiotropic Alleles Commonly Underlie Adaptive Divergence between Natural Populations

2020 ◽  
Vol 196 (1) ◽  
pp. E16-E22
Author(s):  
Ken A. Thompson
Keyword(s):  
Natural Populations ◽  
Adaptive Divergence ◽  
Experimental Hybridization

Evidence that pleiotropic alleles underlie adaptive divergence between natural populations

2019 ◽  
Author(s):  
Ken A. Thompson
Keyword(s):  
Natural Populations ◽  
Transgressive Segregation ◽  
Adaptive Divergence ◽  
Stabilizing Selection ◽  
Experimental Hybridization ◽  
Phenotypic Divergence

The alleles used for adaptation can pleiotropically affect traits under stabilizing selection, and compensatory alleles can be favoured by selection to counteract such deleterious pleiotropy. Such compensatory alleles can segregate in interpopulation hybrids, causing segregation variance for traits where parents have the same phenotype. If adaptation typically involves pleiotropy and compensation, then the segregation variance for traits under stabilizing selection is expected to increase with the magnitude of adaptive phenotypic divergence between parents. This prediction has not been tested empirically, and I gathered data from experimental hybridization studies to evaluate it. I found that pairs of parents which are more phenotypically divergent beget hybrids with more segregation variance in traits where the parents do not differ. This result suggests that adaptive divergence between pairs of natural populations proceeds via pleiotropy and compensation, and that potentially deleterious transgressive segregation variance accumulates systematically as populations diverge.

scholarly journals Evolutionary inference from QST-FST comparisons: disentangling local adaptation from altitudinal gradient selection in snapdragon plants

2018 ◽  
Author(s):  
Sara Marin ◽  
Juliette Archambeau ◽  
Vincent Bonhomme ◽  
Mylène Lascoste ◽  
Benoit Pujol
Keyword(s):  
Local Adaptation ◽  
Natural Populations ◽  
Common Garden ◽  
Global Scale ◽  
Structured Populations ◽  
Adaptive Divergence ◽  
Adaptation To Climate Change ◽  
Phenotypic Differentiation ◽  
Multiple Populations ◽  
Environmental Demand

ABSTRACTPhenotypic differentiation among natural populations can be explained by natural selection or by neutral processes such as drift. There are many examples in the literature where comparing the effects of these processes on multiple populations has allowed the detection of local adaptation. However, these studies rarely identify the agents of selection. Whether population adaptive divergence is caused by local features of the environment, or by the environmental demand emerging at a more global scale, for example along altitudinal gradients, is a question that remains poorly investigated. Here, we measured neutral genetic (FST) and quantitative genetic (QST) differentiation among 13 populations of snapdragon plants (Antirrhinum majus) in a common garden experiment. We found low but significant genetic differentiation at putatively neutral markers, which supports the hypothesis of either ongoing pervasive homogenisation via gene flow between diverged populations or reproductive isolation between disconnected populations. Our results also support the hypothesis of local adaptation involving phenological, morphological, reproductive and functional traits. They also showed that phenotypic differentiation increased with altitude for traits reflecting the reproduction and the phenology of plants, thereby confirming the role of such traits in their adaptation to environmental differences associated with altitude. Our approach allowed us to identify candidate traits for the adaptation to climate change in snapdragon plants. Our findings imply that environmental conditions changing with altitude, such as the climatic envelope, influenced the adaptation of multiple populations of snapdragon plants on the top of their adaptation to local environmental features. They also have implications for the study of adaptive evolution in structured populations because they highlight the need to disentangle the adaptation of plant populations to climate envelopes and altitude from the confounding effects of selective pressures acting specifically at the local scale of a population.

scholarly journals Why are not all chilies hot? A trade-off limits pungency

2011 ◽  
Vol 279 (1735) ◽  
pp. 2012-2017 ◽  
Author(s):  
David C. Haak ◽  
Leslie A. McGinnis ◽  
Douglas J. Levey ◽  
Joshua J. Tewksbury
Keyword(s):  
Seed Production ◽  
Stomatal Density ◽  
Natural Populations ◽  
Pathogenic Fungi ◽  
Adaptive Divergence ◽  
High Moisture ◽  
Reducing Gas ◽  
Trade Offs ◽  
Use Efficiency ◽  
Capsicum Chacoense

Evolutionary biologists increasingly recognize that evolution can be constrained by trade-offs, yet our understanding of how and when such constraints are manifested and whether they restrict adaptive divergence in populations remains limited. Here, we show that spatial heterogeneity in moisture maintains a polymorphism for pungency (heat) among natural populations of wild chilies ( Capsicum chacoense ) because traits influencing water-use efficiency are functionally integrated with traits controlling pungency (the production of capsaicinoids). Pungent and non-pungent chilies occur along a cline in moisture that spans their native range in Bolivia, and the proportion of pungent plants in populations increases with greater moisture availability. In high moisture environments, pungency is beneficial because capsaicinoids protect the fruit from pathogenic fungi, and is not costly because pungent and non-pungent chilies grown in well-watered conditions produce equal numbers of seeds. In low moisture environments, pungency is less beneficial as the risk of fungal infection is lower, and carries a significant cost because, under drought stress, seed production in pungent chilies is reduced by 50 per cent relative to non-pungent plants grown in identical conditions. This large difference in seed production under water-stressed (WS) conditions explains the existence of populations dominated by non-pungent plants, and appears to result from a genetic correlation between pungency and stomatal density: non-pungent plants, segregating from intra-population crosses, exhibit significantly lower stomatal density ( p = 0.003), thereby reducing gas exchange under WS conditions. These results demonstrate the importance of trait integration in constraining adaptive divergence among populations.

scholarly journals Detection of adaptive divergence in populations of the stream mayfly Ephemera strigata with machine learning

2018 ◽  
Author(s):  
Bin Li ◽  
Sakiko Yaegashi ◽  
Thaddeus M Carvajal ◽  
Maribet Gamboa ◽  
Kozo Watanabe
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
River Basin ◽  
Evolutionary Biology ◽  
Natural Populations ◽  
Dispersal Ability ◽  
Adaptive Divergence ◽  
Genome Scanning ◽  
Northeastern Japan ◽  
A Genome

AbstractAdaptive divergence is a key mechanism shaping the genetic variation of natural populations. A central question linking ecology with evolutionary biology concerns the role of environmental heterogeneity in determining adaptive divergence among local populations within a species. In this study, we examined adaptive the divergence among populations of the stream mayfly Ephemera strigata in the Natori River Basin in northeastern Japan. We used a genome scanning approach to detect candidate loci under selection and then applied a machine learning method (i.e. Random Forest) and traditional distance-based redundancy analysis (dbRDA) to examine relationships between environmental factors and adaptive divergence at non-neutral loci. We also assessed spatial autocorrelation at neutral loci to quantify the dispersal ability of E. strigata. Our main findings were as follows: 1) random forest shows a higher resolution than traditional statistical analysis for detecting adaptive divergence; 2) separating markers into neutral and non-neutral loci provides insights into genetic diversity, local adaptation and dispersal ability and 3) E. strigata shows altitudinal adaptive divergence among the populations in the Natori River Basin.

scholarly journals Low but significant genetic differentiation underlies biologically meaningful phenotypic divergence in a large Atlantic salmon population

2015 ◽  
Author(s):  
Tutku Aykanat ◽  
Susan E Johnston ◽  
Panu Orell ◽  
Eero Niemelä ◽  
Jaakko Erkinaro ◽  
...  
Keyword(s):  
Life History ◽  
Genetic Differentiation ◽  
Atlantic Salmon ◽  
Genetic Divergence ◽  
Natural Populations ◽  
Structured Populations ◽  
Life History Strategies ◽  
Adaptive Divergence ◽  
Juvenile Growth ◽  
Significant Genetic Differentiation

Despite decades of research assessing the genetic structure of natural populations, the biological meaning of low yet significant genetic divergence often remains unclear due to a lack of associated phenotypic and ecological information. At the same time, structured populations with low genetic divergence and overlapping boundaries can potentially provide excellent models to study adaptation and reproductive isolation in cases where high resolution genetic markers and relevant phenotypic and life history information are available. Here, we combined SNP-based population inference with extensive phenotypic and life history data to identify potential biological mechanisms driving fine scale sub-population differentiation in Atlantic salmon (Salmo salar) from the Teno River, a major salmon river in Europe. Two sympatrically occurring sub-populations had low but significant genetic differentiation (FST = 0.018) and displayed marked differences in the distribution of life history strategies, including variation in juvenile growth rate, age at maturity and size within age classes. Large, late-maturing individuals were virtually absent from one of the two sub-populations and there were significant differences in juvenile growth rates and size-at-age after oceanic migration between individuals in the respective sub-populations. Our findings suggest that different evolutionary processes affect each sub-population and that hybridization and subsequent selection may maintain low genetic differentiation without hindering adaptive divergence.

scholarly journals Should I stay or should I go? The Ectodysplasin locus is associated with behavioural differences in threespine stickleback

2009 ◽  
Vol 5 (6) ◽  
pp. 788-791 ◽  
Author(s):  
Rowan D. H. Barrett ◽  
Tim H. Vines ◽  
Jason S. Bystriansky ◽  
Patricia M. Schulte
Keyword(s):  
Positive Selection ◽  
Local Adaptation ◽  
Morphological Traits ◽  
Genetic Basis ◽  
Natural Populations ◽  
Threespine Stickleback ◽  
Adaptive Divergence ◽  
Freshwater Habitats ◽  
Repeated Evolution ◽  
Freshwater Environments

Adaptive divergence may be facilitated if morphological and behavioural traits associated with local adaptation share the same genetic basis. It is therefore important to determine whether genes underlying adaptive morphological traits are associated with variation in behaviour in natural populations. Positive selection on low-armour alleles at the Ectodysplasin ( Eda ) locus in threespine stickleback has led to the repeated evolution of reduced armour, following freshwater colonization by fully armoured marine sticklebacks. This adaptive divergence in armour between marine and freshwater populations would be facilitated if the low allele conferred a behavioural preference for freshwater environments. We experimentally tested whether the low allele is associated with preference for freshwater by measuring the preference of each Eda genotype for freshwater versus saltwater after acclimation to either salinity. We found no association between the Eda low allele and preference for freshwater. Instead, the low allele was significantly associated with a reduced preference for the acclimation environment. This behaviour may facilitate the colonization of freshwater habitats from the sea, but could also hinder local adaptation by promoting migration of low alleles between marine and freshwater environments.

scholarly journals ADAPTIVE DIVERGENCE IN PLASTICITY IN NATURAL POPULATIONS OF IMPATIENS CAPENSIS AND ITS CONSEQUENCES FOR PERFORMANCE IN NOVEL HABITATS

Evolution ◽  
2007 ◽  
Vol 55 (4) ◽  
pp. 692-702 ◽  
Author(s):  
Kathleen Donohue ◽  
Elizabeth Hammond Pyle ◽  
Dinan Messiqua ◽  
M. Shane Heschel ◽  
Johanna Schmitt
Keyword(s):  
Natural Populations ◽  
Adaptive Divergence ◽  
Impatiens Capensis

scholarly journals Adaptive divergence in flowering time among natural populations ofArabidopsis thaliana: Estimates of selection and QTL mapping

Evolution ◽  
2016 ◽  
Vol 71 (3) ◽  
pp. 550-564 ◽  
Author(s):  
Jon Ågren ◽  
Christopher G. Oakley ◽  
Sverre Lundemo ◽  
Douglas W. Schemske
Keyword(s):  
Qtl Mapping ◽  
Flowering Time ◽  
Natural Populations ◽  
Adaptive Divergence ◽  
Ofarabidopsis Thaliana

scholarly journals Adaptive Divergence of Meiotic Recombination Rate in Ecological Speciation

2020 ◽  
Vol 12 (10) ◽  
pp. 1869-1881
Author(s):  
Swatantra Neupane ◽  
Sen Xu
Keyword(s):  
Meiotic Recombination ◽  
Recombination Rate ◽  
Natural Populations ◽  
Daphnia Pulex ◽  
Common Garden ◽  
Population Level ◽  
Directional Selection ◽  
Neutral Evolution ◽  
Adaptive Divergence ◽  
Rate Variation

Abstract Theories predict that directional selection during adaptation to a novel habitat results in elevated meiotic recombination rate. Yet the lack of population-level recombination rate data leaves this hypothesis untested in natural populations. Here, we examine the population-level recombination rate variation in two incipient ecological species, the microcrustacean Daphnia pulex (an ephemeral-pond species) and Daphnia pulicaria (a permanent-lake species). The divergence of D. pulicaria from D. pulex involved habitat shifts from pond to lake habitats as well as strong local adaptation due to directional selection. Using a novel single-sperm genotyping approach, we estimated the male-specific recombination rate of two linkage groups in multiple populations of each species in common garden experiments and identified a significantly elevated recombination rate in D. pulicaria. Most importantly, population genetic analyses show that the divergence in recombination rate between these two species is most likely due to divergent selection in distinct ecological habitats rather than neutral evolution.

scholarly journals The genomics of trait combinations and their influence on adaptive divergence

2020 ◽  
Author(s):  
McCall B. Calvert ◽  
Meredith M. Doellman ◽  
Jeffrey L. Feder ◽  
Glen R. Hood ◽  
Peter Meyers ◽  
...  
Keyword(s):  
Emerging Adults ◽  
Allelic Variation ◽  
Genetic Correlations ◽  
Natural Populations ◽  
High Linkage Disequilibrium ◽  
Adaptive Divergence ◽  
Population Divergence ◽  
Rapid Adaptation ◽  
Diapause Termination ◽  
Laboratory Selection

ABSTRACTUnderstanding rapid adaptation requires quantifying natural selection on traits and elucidating the genotype-phenotype relationship for those traits. However, recent studies have often failed to predict the direction of adaptive allelic variation in natural populations from laboratory studies. Here, we test for genomic signatures of genetic correlations to illustrate how multifarious, correlational selection may drive counterintuitive patterns of population divergence in the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae). Apple-infesting populations with relatively early emerging adults have recently evolved from hawthorn-infesting populations consisting of relatively later emerging adults. Multiple studies have reported a paradoxical relationship between population differentiation and seasonal timing, as determined by the timing of diapause termination; alleles associated with late termination occur at higher frequencies in the earlier emerging apple-infesting populations compared to hawthorn-infesting populations. We present evidence that historical selection on diapause termination and another trait, initial diapause intensity, over geographic gradients generated genetic correlations between the traits in a direction antagonistic to contemporary selection on apple-infesting populations. Single nucleotide polymorphism in genomic regions of high linkage disequilibrium associated strongly with diapause termination and intensity, population divergence, geography, and evolutionary responses in laboratory selection experiments. These associations were consistent with geographically variable selection and with correlated evolutionary responses driving higher frequencies of late-associated alleles in the early emerging apple race. In contrast, loci associated only with diapause termination showed the expected pattern (more early-associated alleles in the apple race) in half of the population pairs. Our results suggest that selection on loci demonstrating antagonistic pleiotropy may often shape genomic footprints of rapid adaptation.

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