Dataset Information

Rapid buildup of sympatric species diversity in Alpine whitefish.

ABSTRACT: Adaptive radiations in postglacial fish offer excellent settings to study the evolutionary mechanisms involved in the rapid buildup of sympatric species diversity from a single lineage. Here, we address this by exploring the genetic and ecological structure of the largest Alpine whitefish radiation known, that of Lakes Brienz and Thun, using microsatellite data of more than 2000 whitefish caught during extensive species-targeted and habitat-randomized fishing campaigns. We find six strongly genetically and ecologically differentiated species, four of which occur in both lakes, and one of which was previously unknown. These four exhibit clines of genetic differentiation that are paralleled in clines of eco-morphological and reproductive niche differentiation, consistent with models of sympatric ecological speciation along environmental gradients. In Lake Thun, we find two additional species, a profundal specialist and a species introduced in the 1930s from another Alpine whitefish radiation. Strong genetic differentiation between this introduced species and all native species of Lake Thun suggests that reproductive isolation can evolve among allopatric whitefish species within 15,000 years and persist in secondary sympatry. Consistent with speciation theory, we find stronger correlations between genetic and ecological differentiation for sympatrically than for allopatrically evolved species.

SUBMITTER: Doenz CJ

PROVIDER: S-EPMC6194267 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Rapid buildup of sympatric species diversity in Alpine whitefish.

Doenz Carmela J CJ Bittner David D Vonlanthen Pascal P Wagner Catherine E CE Seehausen Ole O

Ecology and evolution 20180829 18

Adaptive radiations in postglacial fish offer excellent settings to study the evolutionary mechanisms involved in the rapid buildup of sympatric species diversity from a single lineage. Here, we address this by exploring the genetic and ecological structure of the largest Alpine whitefish radiation known, that of Lakes Brienz and Thun, using microsatellite data of more than 2000 whitefish caught during extensive species-targeted and habitat-randomized fishing campaigns. We find six strongly gene ...[more]

PMID: 30377510

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Project description:BACKGROUND: Studying contemporary hybridization increases our understanding of introgression, adaptation and, ultimately, speciation. The sister species Ischnura elegans and I. graellsii (Odonata: Coenagrionidae) are ecologically, morphologically and genetically similar and hybridize. Recently, I. elegans has colonized northern Spain, creating a broad sympatric region with I. graellsii. Here, we review the distribution of both species in Iberia and evaluate the degree of introgression of I. graellsii into I. elegans using six microsatellite markers (442 individuals from 26 populations) and five mitochondrial genes in sympatric and allopatric localities. Furthermore, we quantify the effect of hybridization on the frequencies of the genetically controlled colour polymorphism in females of both species. RESULTS: In a principal component analysis of the microsatellite data, the first two principal components summarised almost half (41%) of the total genetic variation. The first axis revealed a clear separation of I. graellsii and I. elegans populations, while the second axis separated I. elegans populations. Admixture analyses showed extensive hybridization and introgression in I. elegans populations, consistent with I. elegans backcrosses and occasional F1-hybrids, suggesting hybridization is on-going. More specifically, approximately 58% of the 166 Spanish I. elegans individuals were assigned to the I. elegans backcross category, whereas not a single of those individuals was assigned to the backcross with I. graellsii. The mitochondrial genes held little genetic variation, and the most common haplotype was shared by the two species. CONCLUSIONS: The results suggest rapid species turnover in sympatric regions in favour of I. elegans, corroborating previous findings that I. graellsii suffers a mating disadvantage in sympatry with I. elegans. Examination of morph frequency dynamics indicates that hybridization is likely to have important implications for the maintenance of multiple female morphs, in particular during the initial period of hybridization.

Dataset Information

Rapid buildup of sympatric species diversity in Alpine whitefish.

Publications

Rapid buildup of sympatric species diversity in Alpine whitefish.

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