Critically endangered species facing range retreats are not necessarily genetically depleted: the case of the endemic freshwater fish Anaecypris hispanica (Steindachner, 1866)

Abstract

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Assessing genetic diversity levels and population structure is fundamental for conservation and management of highly threatened species. In this study we use mitochondrial and nuclear markers to address phylogeographic and demographic data on the critically endangered Anaecypris hispanica (Cyprinidae). The populations of this species are strongly differentiated (high and significant ФST and FST values, corroborated by the results from AMOVA and SAMOVA) and genetically diversified. We suggest that the restricted gene flow between populations may have been potentiated by ecological, hydrological and anthropogenic causes. Bayesian skyline plots revealed a signal for expansion for all populations (tMRCA between 68kya and 1.33Mya) and a genetic diversity latitudinal gradient was detected between the populations from the Upper (more diversified) and the Lower (less diversified) Guadiana river basin. Distribution models inferred for this species highlight the significant contribution of temperature seasonality and isothermality for the occurrence of A. hispanica in Guadiana environments and emphasize the importance of stable climatic conditions for the preservation of this species. Given the strong population structure found, high percentage of private haplotypes and virtual absence of inter-basin gene flow we suggest that each A. hispanica population should be considered as an independent Operational Conservation Unit.

Keywords

• Genetics, Population
• mtDNA
• nuclear DNA
• Population unit
• Endemic freshwater fish