| Summary: | The killifish, Aphanius baeticus and Aphanius iberus (Cyprinodontidae) are endemic species restricted to river basins on Spain’s southern Atlantic and Mediterranean coastline, respectively. As a secondary fresh-water fish fauna of the Iberian Peninsula basin, their distribution is primary restricted to local coastal streams, salt water creeks, and man-made salt evaporation ponds, which are susceptible to periodical flood and drought events. For small species with low dispersal capacity such as A. baeticus and A. iberus these events may influence severely in their demography. However, despite having similar ecological traits and living in similar environmental conditions, both species show striking differences in their levels of genetic diversity and demography. Other factors, such as historical events and more recently human-mediated threats may have contributed differently in shaping current genetic structure of killifish ichthyofauna from the Iberian Peninsula.
In this work, we present comparative genetic structure, diversity and historical demography analyses of A. baeticus and A. iberus using mitochondrial (cytochrome b, gene) and nuclear (microsatellite) markers in both natural and introduced populations across their entire distribution range. We used Bayesian genetic structure analysis and coalescent simulations using nuclear microsatellite diversity to determine changes in effective population size and the timing of possible population expansions or declines. Moreover, inferred past demographic changes based on mtDNA were determined in order to discern the possible contribution of historical and human-mediated effects on their current population structure.
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