Sampling genetic diversity in the sympatrically and allopatrically speciating Midas cichlid species complex over a 16 year time series.

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Type
Article: article from journal or magazin.
Collection
Publications
Title
Sampling genetic diversity in the sympatrically and allopatrically speciating Midas cichlid species complex over a 16 year time series.
Journal
BMC Evolutionary Biology
Author(s)
Bunje P.M., Barluenga M., Meyer A.
ISSN
1471-2148
Publication state
Published
Issued date
2007
Volume
7
Number
25
Pages
25
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Abstract
BACKGROUND: Speciation often occurs in complex or uncertain temporal and spatial contexts. Processes such as reinforcement, allopatric divergence, and assortative mating can proceed at different rates and with different strengths as populations diverge. The Central American Midas cichlid fish species complex is an important case study for understanding the processes of speciation. Previous analyses have demonstrated that allopatric processes led to species formation among the lakes of Nicaragua as well as sympatric speciation that is occurring within at least one crater lake. However, since speciation is an ongoing process and sampling genetic diversity of such lineages can be biased by collection scheme or random factors, it is important to evaluate the robustness of conclusions drawn on individual time samples. RESULTS: In order to assess the validity and reliability of inferences based on different genetic samples, we have analyzed fish from several lakes in Nicaragua sampled at three different times over 16 years. In addition, this time series allows us to analyze the population genetic changes that have occurred between lakes, where allopatric speciation has operated, as well as between different species within lakes, some of which have originated by sympatric speciation. Focusing on commonly used genetic markers, we have analyzed both DNA sequences from the complete mitochondrial control region as well as nuclear DNA variation at ten microsatellite loci from these populations, sampled thrice in a 16 year time period, to develop a robust estimate of the population genetic history of these diversifying lineages. CONCLUSION: The conclusions from previous work are well supported by our comprehensive analysis. In particular, we find that the genetic diversity of derived crater lake populations is lower than that of the source population regardless of when and how each population was sampled. Furthermore, changes in various estimates of genetic diversity within lakes are minimal and provide no evidence for drastic changes during the last 20 years, supporting the hypothesis that the processes which have resulted in rapid speciation are primarily historical. In contrast, there is some evidence for ongoing evolution, particularly selection, in all lakes except crater Lake Masaya, perhaps reflecting the persistence of speciational processes. Importantly, we find that the crater Lake Apoyo population, for which strong evidence of sympatric speciation has been demonstrated, has lower genetic diversity than other crater lakes and the strongest evidence for ongoing selection.
Keywords
Animals, Cichlids, DNA, Mitochondrial, Evolution, Molecular, Genetic Markers, Genetic Speciation, Genetic Variation, Haplotypes, Nicaragua
Pubmed
Open Access
Yes
Create date
19/11/2007 10:45
Last modification date
20/08/2019 15:23
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