The genetic legacy of polyploid Bolivian Daphnia: the tropical Andes as a source for the North and South American D. pulicaria complex.
We investigated genetic variation in asexual polyploid members of the water flea Daphnia pulex complex from a set of 12 Bolivian high-altitude lakes. We used nuclear microsatellite markers to study genetic relationships among all encountered multilocus genotypes, and combined this with a phylogenetic approach using DNA sequence data of three mitochondrial genes. Analyses of mitochondrial gene sequence divergence showed the presence of three very distinct clades that likely represent cryptic undescribed species. Our phylogenetic results suggest that the Daphnia pulicaria group, a complex of predominantly North American species that has diversified rapidly since the Pleistocene, has its origin in South America, as specific tests of topology indicated that all three South American lineages are ancestral to the North American members of this species group. A comparison between variation of nuclear and mitochondrial markers revealed that closely related polyploid nuclear genotypes sometimes belonged to very divergent mitochondrial lineages, while distantly related nuclear genotypes often belonged to the same mitochondrial lineage. This discrepancy suggests that these South American water fleas originated through reciprocal hybridization between different endemic, sexually reproducing parental lineages. It is also likely that polyploidy of the investigated lineages resulted from this hybridization. Nevertheless, no putative diploid parental lineages were found in the studied region.
Mergeay
Joachim
J
Laboratory of Aquatic Ecology and Evolutionary Biology, Katholieke Universiteit Leuven, Charles Deberiotstraat 32, B-3000 Leuven, Belgium. joachim.mergeay@bio.kuleuven.be
Aguilera
Ximena
X
Declerck
Steven
S
Petrusek
Adam
A
Huyse
Tine
T
De Meester
Luc
L
D000531:Altitude; D000818:Animals; D001483:Base Sequence; D001838:Bolivia; D004272:DNA, Mitochondrial / Q000235:genetics; D003621:Daphnia / Q000235:genetics*; D014644:Genetic Variation; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009656:North America; D010802:Phylogeny; D011123:Polyploidy; D017422:Sequence Analysis, DNA
D004272:DNA, Mitochondrial