Data from: Founder effects determine the genetic structure of the water flea Daphnia in Ethiopian reservoirs

Founder effects introduce stochasticity in the genetic structure of
species at the regional scale. To the extent that founder effects are
important, they will result in a reduced signature of space, time, and
environmental variation in landscape genetic data. We studied the
metapopulation genetic structure of recently founded populations of the
microcrustacean Daphnia sinensis in 10 Ethiopian water reservoirs. We used
three different approaches to estimate the number of effective founders
and applied them to two independent genetic marker sets in an effort to
investigate the role of founder effects and to estimate effective size of
the founding population. Estimates of founding sizes rarely exceeded eight
individuals but were most often limited to less than four individuals. No
associations of genetic identities, gene frequencies, measures of genetic
diversity, or differentiation with environmental and spatial variables
were found. Age and size of the reservoirs were not correlated with
genetic diversity measures or number of founders in these reservoirs.
These findings indicate that neither strong selection, nor dispersal
limitation are responsible for the observed pat- tern of genetic
variation. Our results suggest a regional population structure that is
strongly impacted by founder events, reflecting colonization by just a few
founders per waterbody, and not noticeably influenced by subsequent
dispersal and gene flow. Our results show that rapid colonization of empty
habitats and fast population growth by a handful of founders can result in
strong founder effects, even in relatively large habitats that are likely
regularly reached by new immigrants.

Version Sep 27, 2018