Genetic and morphological analyses indicate high population mixing in the endangered cichlid Alcolapia flock of East Africa

Citation:
Zaccara S, Mavuti KM, Crosa G, Vanetti I, Binelli G, Harper DM, Balarin JD, Britton RJ. "Genetic and morphological analyses indicate high population mixing in the endangered cichlid Alcolapia flock of East Africa." Conservation Genetics. 2013.

Abstract:

Alcolapia is a minor genus of small-bodied, polymorphic cichlids inhabiting the lagoons and hot
springs surrounding the soda lakes Natron (largely in Tanzania) and Magadi (Kenya). Three
Alcolapia species are present at Natron (Alcolapia alcalicus, Alcolapia ndalalani and Alcolapia
latilabris) and one at Magadi (Alcolapia grahami). All are IUCN Red Listed as either vulnerable
or endangered. We performed analyses of morphometric and genetic structure on 13 populations
of the Natron Alcolapia flock, and one A. grahami population of Lake Magadi as an out-group.
Morphometric analyses revealed significant differentiation in the head and mouth shape of the
species at Natron. From a genetic perspective, among 70 mtDNA control region sequences 17
haplotypes were found, showing in the minimum spanning network a star-like pattern around the
widespread haplotype 2lat. At Natron, there was limited genetic differentiation between the
different populations of A. alcalicus and A. latilabris, despite apparent ecological barriers of
extreme alkalinity that suggested their populations were isolated. Instead, there appeared to be
some population connectivity, with a rate of 0.5–2.3 migrants per generation suggesting that
natural factors, such as intense rains or transmission by large piscivorous birds, facilitate
population connectivity and maintain genetic similarity. The outputs of high population
connectivity and one genetic unit at the basin level (despite morphological divergence) suggest
that any human activities that disrupt the connectivity of the freshwater resources of the Natron
catchment could further threaten the integrity and current status of these already threatened fish
populations.

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