World Congress of Malacology Antwerp ... - Unitas Malacologica

Challenging the biogeographical scenario of diversification of the Ampullariidae
(Caenogastropoda) using molecular methods
Schultheiß, Roland; Geertz, Thies; Heiler, Katharina; Albrecht, Christian
Department of Animal Ecology & Systematics, Justus Liebig University Giessen, Heinrich-Buff-
Ring 26-32 IFZ, D-35392 Giessen, Germany,
Email: Roland.Schultheiss@allzool.bio.uni-giessen.de; ThiesGeertz@googlemail.com;
KatharinaHeiler@gmx.de; Christian.Albrecht@allzool.bio.uni-giessen.de
Members of the gastropod family Ampullariidae Guilding, 1828 have a considerable impact on
human life: Pomacea spp., for example, are known as invasive pest species, affecting paddy fields in
Asia. Marisa cornuarietis (Linneaus, 1758), on the other hand, serves in Africa as intermediate host
for the blood fluke Schistosoma bovis Sonsino, 1876. However, the intergeneric relationships of this
circumtropically distributed family and, therewith, hypotheses on its origin and diversification
patterns have barely been addressed in recent literature.
In the present study, we provide preliminary data that challenge, in part, the current conception of
ampullariid diversification based on anatomical and morphological data. We used DNA sequence
data of two mitochondrial fragments (ribosomal LSU and NADH dehydrogenase subunit 1) and
included specimens from North and South America as well as from Africa in our analyses. The
dataset included the proposed most basal ampullariid genus Afropomus Pilsbry & Bequaert, 1927 as
well as the widely distributed African genus Lanistes Montfort, 1810 – both have so far not been
subject to molecular phylogenetic analyses. We compared the results of various phylogenetic
reconstructions (including Bayesian inference, Maximum Parsimony and Neighbour Joining) and
found two consistent patterns that are in conflict with the anatomically and morphologically based
hypotheses: first, our analyses indicate a sister taxon relationship between Lanistes and Pila Röding,
1798, the other in Africa widely distributed genus. Therewith, the most recent common ancestor
(MRCA) of Pila is probably not – as so far suggested – also the MRCA of all non-African
ampullariid snails. Second, the basal position of Afropomus within the ampullariids could not be
confirmed beyond any doubt. We discuss the biogeographical implications of these finding with
respect to the current hypotheses and suggest a new scenario for the diversification of this gastropod
family.
Effects of parasitic mites on behavior and life-history traits of their host, the land snail Arianta
arbustorum
Schüpbach, Hans Ulrich; Baur, Bruno
Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St.
Johanns-Vorstadt 10, CH-4056 Basel, Switzerland,
Email: H.Schuepbach@unibas.ch; Bruno.Baur@unibas.ch
Parasites can influence the population dynamics of their hosts by affecting life-history strategies and
behavior. The hematophageous mite Riccardoella limacum lives in the lung cavity of terrestrial
gastropods. We investigated parasite-induced changes in the behavior and life-history traits of the
simultaneously hermaphroditic land snail Arianta arbustorum, a common host of R. limacum.
Naturally infected A. arbustorum collected in the wild showed a decreased activity compared to
uninfected snails. The reproductive output, expressed as the number of eggs deposited in a
reproductive season, was reduced in mite-infected hosts. However, the hatching success of the eggs
laid by parasitized snails was slightly higher than that of uninfected individuals. We also examined
winter survival in 361 adults of A. arbustorum collected from 4 natural populations. Prevalence of
mite infection ranged 44.8–70.1% in three populations (snails in the fourth population were not
infected). Winter survival was reduced in infected snails in 2 of 3 populations. The reduced
reproductive output and winter survival indicate that parasite pressure imposed by R. limacum might
be an important factor in the life-history evolution of A. arbustorum populations. Further, the reduced
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