Parallel speciation between marine and stream-resident strickleback. On the contrary, the freshwater and marine fish retain their numerous traits in terms of shape, physiology and behaviour, and also display distinct gene pools. Sampling has confirmed that the partly recessive, low-armor allele is present as standing variation in the marine population (42, 53).
Predictable Patterns of Disruptive Selection in Stickleback in Postglacial Lakes. Here, we show that there is a general trend toward weak disruptive selection on trophic morphology in three-spine stickleback (Gasterosteus aculeatus) in 14 lakes on Vancouver Island. Sympatric speciation in animals: the ugly duckling grows up. In our model gene flow facilitates multitrait parallel evolution and speciation on a large geographic scale. We focus on progress in understanding ecological speciation between adjacent marine and stream-resident threespine stickleback populations. Field data on this species are used to estimate some of the parameters of the model. Tracking the development of new model systems, Skepticism toward Santa Rosalia, or why are there so few kinds of animals, Fitness Landscapes and the Origin of Species, Allele substitution at a flower color locus produces a pollinator shift in monkeyflowers, Pollinator preference and the evolution of floral traits in monkeyflowers (, Ecological speciation in sticklebacks: Environment-dependent hybrid fitness, A genetic interpretation of ecologically dependent isolation, A test of ecologically dependent postmating isolation between sympatric sticklebacks, Reproductive isolation as a pleiotropic effect of copper tolerance in, The genetic basis of intrinsic and extrinsic postzygotic reproductive isolation jointly promoting speciation in the lake whitefish species complex (, Incipient speciation by divergent adaptation and antagonistic epistasis in yeast, Two Dobzhansky-Muller genes interact to cause hybrid lethality in, Incompatibility of nuclear and mitochondrial genomes causes hybrid sterility between two yeast species, A mouse speciation gene encodes a meiotic histone H3 methyltransferase, The population genetics of adaptation: The distribution of factors fixed during adaptive evolution, Ecological divergence exhibits consistently positive associations with reproductive isolation across disparate taxa, Body size divergence promotes postzygotic reproductive isolation in centrarchids, Dynamics of hybrid incompatibility in gene networks in a constant environment, Dobzhansky-Muller incompatibilities and adaptation to a shared environment, Adaptation from standing genetic variation, Widespread parallel evolution in sticklebacks by repeated fixation of Ectodysplasin alleles, How species evolve collectively: Implications of gene flow and selection for the spread of advantageous alleles. This article is a PNAS Direct Submission. Most marine populations are anadromous, migrating to streams to breed and returning to sea afterward. Phenotypic (outward) diversity, resulting from the genotype’s interaction with the environment, is so great that natural historians and taxonomists initially described these populations as separate species. Perspective: Models of speciation: What have we learned in 40 years? The genetic mechanisms that permit its evolution and/or persistence have received considerable attention, particularly when there is gene flow between populations.
The basic assumption of this model is that intra-specific competition for resources can lead to ecological specialization to different niches, ... Sympatric speciation remains an controversial topic in evolutionary biology, mostly for the limited empirical support of the mechanisms putatively underlying it and that combine strong effects of disruptive selection and assortative mating. With significant gene flow, premating isolation is unlikely to arise or persist unless the genes underlying it somehow overcome the antagonism between selection and recombination, such as by pleiotropy or by reduced recombination with genes under divergent natural selection. Disruptive selection and assortative mating were varied systematically from γ=0 to 0.5 and r=0 to 0.95, in increments of 0.025. economics or sociology), Environmental changes, such as those associated with global climate change, can affect the stability of natural communities.
This paper presents a test of this theory, using natural populations of the three-spine stickleback, Gasterosteus aculeatus. This mechanism of biodiversity loss, often termed reverse speciation or introgressive extinction, is of exceptional interest because the parent species are typically highly differentiated ecologically. (B) Global phylogeny of Eda gene sequences from marine high-armor and freshwater low-armor stickleback populations. However, the question remains as to where the standing variation in the sea comes from and how it is maintained. We show that evolution under branching conditions selects for assortativeness and thus allows sexual populations to escape from fitness minima. This implies that speciation in Pundamilia used preexisting genetic variation. The lizard species, Anolis roquet, illustrates the kind of population treated by the model. (c) Phenotypic and diet variation are correlated: fish with longer gill rakers tend to consume a more limnetic diet (high values of isotopic PC1 indicate lower δ13C, higher δ15N; First Lake). The paradox is that the hallmark rapid burst pattern of adaptive radiation is contradicted by most speciation models, which predict continuously decelerating diversification and niche subdivision. Recently, a large-scale cooperation project employed the latest whole genome sequencing techniques to investigate the genomic basis for adaptive divergence between marine and freshwater sticklebacks [6].
We present a hypothesis for the repetitive origin of freshwater stickleback species involving natural selection of standing genetic variation. Interestingly, these loci include genes related to immunity, ion transporters and cell adhesion proteins.
Thus, sexual selection, like other mechanisms of postzygotic isolation between young sister species, may be stronger in a wild setting than in the laboratory because of habitat-specific selection pressures. In each lake I removed fish from one enclosure and added them to the other to create paired low- and high-population-density treatments with natural phenotype distributions. Many species have developed special traits to ensure their survival and reproduction in a particular environment. The authors declare no conflict of interest. Mating success and male courtship behaviors in three populations of the threespine stickleback. We recommend that commenters identify themselves with full names and affiliations. In comparison to the protein-coding genes, the non-coding DNA makes up the largest part of the genome, almost 90%. Why asymmetric mating preferences may not show the direction of evolution. 2: In recent times, the threespine stickleback (Gasterosteus aculeatus) has undergone adaptive radiation, evolving from the typical marine ecotype (red) into freshwater ecotypes (blue) with a number of different shapes. Discuss the status of benthic and limnetic stickleback fish as distinct species, with reference to different species concepts (biological, morphological, ecological). The model shows that there is an optimum number of individuals of each phenotype for a given set of resources and a given regime of interphenotypic competition. Particularly, protocadherins are involved in neuronal network formation; they may play a central role in P. microlepis’ asymmetry, especially in behavioral lateralization. (a) With no disruptive selection and no assortative mating (γ=0, r=0), phenotypic variance follows a binomial (approximately normal) distribution whose variance depends on the level of polymorphism at the 40 additive loci, maintained by mutation-drift balance. Today, sticklebacks exist in many different shapes and sizes (fig. Finally, for similar reasons the role of standing genetic variation in speciation is likely to be greater under ecological speciation than under mutation-order speciation. Divergence occurs by chance under the mutation-order process. 2004;Nosil et al. Here, we take a broad view of what constitutes an adaptive radiation, and seek to find commonalities among disparate examples, ranging from plants to invertebrate and vertebrate animals, and remote islands to lakes and continents, to better understand processes shared across adaptive radiations. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates. In contrast, quantitative genetic models of speciation assume that response to selection, at least in the early stages of divergence, is based on standing genetic variation (45, 46). A test of ecological selection against young-of-the-year hybrids of sympatric sticklebacks. Later, Dobzhansky (2) and Mayr (3) defined species and speciation by the criterion of reproductive isolation instead. Reduced viability of the parental species in this habitat mapped to a QTL identified as the salt tolerance gene CDPK3 (19).
Questions: Are morphological, Disruptive selection is often assumed to be relatively rare, because it is dynamically unstable and hence should be transient.
was trapped and became adapted to local conditions in the lake, … 4A) suggest that the stream ecotype has originated multiple times independently in coastal bodies of water around the Northern Hemisphere. This result is confirmed by a high Mantel correlation between percentage sequence divergence and geographic distance (z = 0.97, P = 0.002). Felsenstein (21) pointed out that in the absence of very strong reproductive isolation between hybridizing populations recombination between genes governing assortative mating and genes under divergent natural selection will cause existing levels of assortative mating between populations to decay and inhibit the evolution of even stronger assortative mating. © 2008-2020 ResearchGate GmbH. The relationships in each panel of this figure are repeatable across multiple solitary lake populations. This article demonstrates that selection regimes leading to evolutionary branching readily arise from a wide variety of different ecological interactions within and between species.
1). Branch lengths are not scaled to a comparable age between plots. The Jones group studies how variation in genome function in natural populations facilitates adaptation to different environments and the evolution of new species. 4B).
In a relatively short timeframe, they have evolved an extraordinary phenotypic diversity reflecting adaptations to often very narrow niches. analyzed data; and D.S. My study reveals that divergence in sexual traits other than acoustic signals, although dramatically less obvious in nature, is present among Mecopoda elongata populations. The hypothesis does not address where or when an advantageous mutation arose, but proposes that once a mutation reaches appreciable frequency in a freshwater population it could participate in the transporter process.
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