2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

�135 Claus Fischer A 703 / 17:00
Evidence for a mechanism of genetic exchange in an ancient asexual bdelloid rotifer
Authors: Claus Fischer 1 , W.H. Ahlrichs 1 , Olaf R.P. Bininda-Emonds 1
Affiliation: 1 AG Systematics and Evolutionary Biology, IBU Faculty V, Carl von
Ossietzky Universität Oldenburg
Bdelloid rotifers have been labelled as an evolutionary scandal for being ancient
asexuals. Indirect evidence of ancient horizontal gene transfer in bdelloids provides a
partial explanation of how this group might have escaped the progressive
accumulation of deleterious mutations associated with asexual reproduction (a
phenomenon known as Muller’s ratchet). However, rather than being an accidental
occurrence, we present the first empirical evidence that DNA is actively taken up at
adult stages by the asexual bdelloid Philodina roseola. This ability is not present in the
facultative asexual monogonont rotifer Brachionus rubens.
Three additional results hint that this ability could facilitate the exchange of genetic
material as an imperfect analogue of sexual reproduction. First, the amount of DNA
apparently retained by P. roseola correlates roughly with the phylogenetic
relatedness of its donor species. Second, in agreement with theory, the incorporated
DNA results in an increased variance in the reproductive output of the F1 generation,
but only if the parental generation has undergone desiccation. Third, these effects
are also seen when individuals are desiccated in groups (and can therefore act as
DNA donors), but not individually. Taken together, our results indicate a mechanism
for regular genetic exchange in bdelloid rotifers that favours more closely related
individuals / taxa, thereby potentially providing an answer to the riddle as to how the
‘asexual’ bdelloids have escaped being ground down by Muller’s ratchet for over 35
million years.
�136 Alireza Keikhosrav A 703 / 17:15
Cryptic species in European freshwater crabs revealed by genetic comparison of
populations of Potamon ibericum (Brachyura, Potamidae)
Authors: Alireza Keikhosravi 1 , Sebastian Klaus 2 , PD Dr. Christoph D. Schubart 1
Affiliations: 1 Biologie 1, Universität Regensburg; 2 Ecology and Evolution, Goethe
Universität, Frankfurt a.M., Germany
Potamon ibericum (Bieberstein, 1808) is a well known freshwater crab species
distributing from the southeastern Balkan Peninsula to the tributaries of the Caspian
Sea. This study aims to describe the population genetic structure of P. ibericum,
reconstruct gene flow patterns within and among faunal regions, and investigate the
presence of possible cryptic lineages. Specimens for the current study were collected
from an introduced population in France and from native populations in Bulgaria,
Greece and Iran. A partial fragment of approximately 900 basepairs of the
mitochondrial gene cytochrome oxidase 1 was amplified and sequences compared
and analysed.
Our results show restricted gene flow and high genetic heterogeneity among faunal
regions. The strongest differentiation is observed between the Caspian and the Black-
Aegean Sea drainage systems, respectively. Within the latter, populations from
southwestern Bulgaria and northern Greece from rivers draining into the northern
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