World Congress of Malacology Antwerp ... - Unitas Malacologica

Multivariate statistical analysis of quantitative traits is a powerful technique used to investigate
geographical variation of populations. It has provided useful results for assessing stock structure of
several species, because it can yield information complementary to that derived from biochemical,
physiological and life history studies. Principal component analysis (PCA) was used to test for the
contribution of these traits in the configuration of variance. Forward stepwise discriminant analysis
(DA) based on the generalized Mahalanobis distance was used to determine the similarity between
populations and the ability of these traits to identify the specimens correctly. A dendrogram of
phenotypic relationships was constructed based on Mahalanobis distances using UPGMA cluster
analysis.
Diversity, speciation and historical biogeography of Bullidae
Malaquias, Manuel António E.; Reid, David G.
Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK,
Email: m.malaquias@nhm.ac.uk
Phylogenetic relationships and historical biogeography of the worldwide gastropod family Bullidae, a
monophyletic assemblage of mainly tropical species inhabiting shallow seagrass and sandy-mud
areas, are inferred by Bayesian analysis of individual and combined genes (mitochondrial
cytochrome oxidase I and 16S rRNA, and nuclear 28S rRNA). The geographical mode and time of
speciation are hypothesized from the phylogeny, fossil evidence and geographical distributions of
extant species. The geographical pattern of speciation was assessed by plotting percentage of range
overlap between sister clades against age of nodes; divergence times (age of nodes) and rates of
evolution were calculated by penalized likelihood with fossil ages; and a lineage-through-time plot
was used to assess diversification rate. The family Bullidae had its origin in the tropical Tethys Sea
and during the Miocene was widespread across the Tethyan realm. Major tectonic events like the
closure of Tethys Sea and the uplift of the Isthmus of Panama, coupled with cold-water currents
around South Africa and expanses of open ocean (East Pacific and Mid-Atlantic Barriers) shaped the
phylogenetic structure of Bullidae, resulting in a monophyletic assemblage in the tropical Indo-West
Pacific and another in the Atlantic plus Eastern Pacific. Within the latter clade there are sister
relationships across the Isthmus of Panama, and on both sides of the Atlantic Ocean. Allopatry is the
only mode of speciation in Bullidae, and both vicariance and dispersal played important roles in the
formation of species. Despite the orthodox view that Plio-Pleistocene sea-level oscillations have
promoted speciation in shallow-marine organisms, the origin of extant species of Bullidae dates from
the Miocene. Patterns of diversity conform roughly to the general trend observed in tropical
organisms, with a maximum of six species in the Indo-West Pacific region as a whole (and up to
three sympatric in its central part) and two species each in the East Pacific, Western Atlantic and
Eastern Atlantic regions. The southern Australasian species Bulla quoyii is hypothesized to be a
Tethyan relict that is sister to the Atlantic plus eastern Pacific clade. This provides the first molecular
support for the idea that southern Australia is a refuge of Tethyan fauna.
Diversity and distribution of Haminoea (Gastropoda: Cephalaspidea) in the Atlantic and
eastern Pacific oceans
Malaquias, Manuel António E.; Reid, David G.
Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK,
Email: m.malaquias@nhm.ac.uk
This is a new project, recently begun with the aim of combining data on shells, anatomy, fossil record
and molecular sequences of all available species of Haminoea in a systematic, phylogenetic and
biogeographic analysis. The main objectives are to review and clarify the systematics of the group,
and to produce a species-level phylogeny as a basis for hypotheses of origin, speciation and historical
biogeography. The genus Haminoea occurs worldwide in tropical and temperate habitats, inhabiting
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