2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

ias the population sex-ratio. Especially small isolated populations are predicted to
go extinct under these conditions. However, in some species, males have been found
to sire offspring that may be triploid. We studied the parasitic wasp Bracon
brevicornis laying clutches of eggs on their lepidopteran host larvae and thus having a
large potential for diploid male production through sib-mating. We analysed diploid
male production, diploid male fertility and diploid male recognition by females and
found that diploid males are not fully sterile but that some of them produced triploid
daughters. Although most of these triploid females were sterile some succeeded in
producing either a son or a daughter.
9. Evolutionary Biology POSTERS
����61 Bianca Aichinger
Do closely related marine coastal crab species hybridize? A case example with
European representatives of the genus Pilumnus (Brachyura: Pilumnidae)
Authors: Bianca Aichinger 1 , C.D. Schubart
Affiliations: 1 Biologie I, Universität Regensburg
Bristle crabs of the genus Pilumnus are commonly found in shallow waters along the
European coast. They are easily identifiable as a genus, but intrageneric classification
is quite complex (based on the presence of pereiopodal spines and/or the shape of
characteristic bristles). Overall, there is no general agreement on the number and
nomenclature of species that should be recognized from European waters. Therefore,
this genus is well-suited for comparative molecular taxonomic studies. Specimens of
the presumed species Pilumnus hirtellus (Linnaeus, 1761), P. villosissimus
(Rafinesque, 1814), P. spinifer (H. Milne Edwards, 1834), P. aestuarii (Nardo, 1869),
and Pilumnus sp. 1 (d’Udekem d’Acoz, 1994) were gathered from as many localities
as possible ranging from the Black Sea to Atlantic islands. DNA sequence data were
obtained from different mitochondrial genes and used for reconstruction of
phylogenetic trees and haplotype networks. We tested for hybridization with large
sample size mtDNA sequencing of a population with mixed morphological characters
and with AFLP analyses. Our results give evidence for five mitochondrial haplogroups
within the species complex that correspond to the above mentioned species. There is
little geographic variation, suggesting high levels of gene flow within the presumed
species. AFLP data are currently being analyzed. The European crabs of the Pilumnus
hirtellus complex represent a good case study to define evolutionary units. If they will
be confirmed as good species, they must be relatively young, and we may possibly
witness ongoing processes of morphological, genetic, and ecological differentiation.
The mechanisms and origin of the postulated recent genetic isolation remain to be
investigated.
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