World Congress of Malacology Antwerp ... - Unitas Malacologica

Does ecological specialization lead to speciation? – a case study on Tylomelania sarasinorum
from the Malili lake system (Sulawesi, Indonesia)
von Rintelen, Kristina; Glaubrecht, Matthias; von Rintelen, Thomas
Museum of Natural History, Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin,
Germany,
Email: kristina.rintelen@museum.hu-berlin.de
Ancient lakes and their endemic faunas are model systems to study evolutionary patterns and add to
our understanding of speciation processes. In this context the Malili lake system in the central
highlands of the Indonesian island Sulawesi is no exception. It harbours an endemic species flock of
29 species of the viviparous freshwater snail Tylomelania (Cerithioidea, Pachychilidae), which is
endemic to Sulawesi. The focus of this study is on Tylomelania sarasinorum (Kruimel, 1913), a hardsubstrate
dweller in Lake Towuti, the largest and southernmost of the five connected Malili lakes. In
contrast to other species from the system, a conspicuous radula polymorphism with five
distinguishable forms is found in T. sarasinorum, while the shell is generally rather uniform. Several
of the 36 populations sampled showed a correlation between a radula form and a specific substrate
(wood and rocks), albeit sporadic. Just in a few populations from the north coast of Loeha Island,
located in the middle of the lake, were the radula forms are not only strongly correlated with the
different substrates, but also with distinct shell morphologies (shell shape and aperture colour).
Moreover, preliminary molecular data from amplified fragment length polymorphism (AFLP)
analyses reveal a genetic separation of both morphs on Loeha Island. We suggest that this indicates
an example of incipient speciation, where ecological factors, i.e. substrate specific specialization of
the radula, play an essential role.
Preliminary rDNA sequence data on arionid phylogeny
Vrijders, Hilde 1 ; Breugelmans, Karin 1 ; Jordaens, Kurt 2 ;Backeljau, Thierry 1,2
1. Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium,
Email: Hilde.Vrijders@naturalsciences.be; thierry.backeljau@naturalsciences.be
2. Evolutionary Biology Group, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp,
Belgium,
Email: kurt.jordaens@ua.ac.be
The phylogenetic relationships within the terrestrial slug 'family' Arionidae are still highly
controversial. Recent studies, based on nuclear ribosomal ITS1 and mtDNA sequence data, provided
many new insights, particularly with respect to species relationships in the genus Arion, but at the
same time appeared inconclusive with respect to relationships between genera and 'subfamilies'.
The present contribution explores to what extent arionid relationships can be resolved by DNA
sequence data of the complete 18S rDNA gene and stretches of the rDNA cluster including the 3’end
of the 5.8S gene, the complete ITS2 region, and the 5’end of the large ribosomal subunit (28S).
To this end we aim to assess (a) deep phylogeny within the 'Arionidae' at 'subfamilial' and generic
levels, (b) 'subgeneric' relationships within the Arioninae, (c) the position of Arion franciscoloi, and
(d) the status of the Carinarion-complex.
Preliminary results suggest that: (a) A. franciscoloi occupies a basal position relative to the genera
Arion, Geomalacus and Ariunculus (18S data only) or occupies a basal position relative to the genus
Arion only (5.8S –ITS2 –28S stretch and combined data set), (b) the subfamily Anadeninae is
probably not monophyletic, (c) the subfamily Ariolimacinae seems monophyletic but the
relationships between Ariolimax sp. remain unresolved, (d) the subgenera Mesarion and Arion as
currently interpreted, cannot be separated, (e) the genus Geomalacus is paraphyletic relative to
Letourneuxia, (f) the subgenera Kobeltia and Microarion are confirmed as a single taxon, and (g) the
Carinarion-complex shows nearly no sequence variation for the rDNA sequences used, reinforcing
the idea that the taxa involved may be not distinct at the species level.
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