C. Brito

Conservation genetics of the endemic Azorean slug Plutonia atlantica (Mollusca, Pulmonata)

Abstract Fifty-six specimens of the rare and endangered, endemic Azorean carnivorous slug, Plutonia atlantica , were surveyed for variation at 13 putative allozyme loci in eight populations from three islands. Genotypic proportions showed no significant deviations from Hardy–Weinberg equilibrium expectations and average observed and expected heterozygosity values were H o =0.109 and H e =0.118. At nearly all loci there were significant allele frequency differences between populations. Hierarchical F -statistics, genetic distances (identities), allelic distributions, and an independent analysis of isoelectric focused esterase profiles, suggested that genetic variation in P. atlantica is geographically structured, i.e. within the island of Sao Miguel (Tronqueira region vs the remainder of the island), between islands and between island groups (Faial/Pico vs. Sao Miguel). Genetic distances between populations from any of these geographic units were typical for interspecific comparisons. Therefore, it was concluded that conservation efforts in P. atlantica should recognize at least four management units (Faial, Pico, Tronqueira in Sao Miguel and the remainder of Sao Miguel), in order to effectively preserve the currently known genetic diversity in this species. How far these management units represent evolutionarily significant units or even different taxa remains to be investigated.

Radular myoglobin and protein variation within and among some littorinid species (Mollusca : Gastropoda)

The radular muscles of several littorinid species, including Littorina littorea, L. saxatilis, L. obtusata, L. striata and Melarhaphe neritoides, contain myoglobin (Mb). Here we report on the presence of radular Mb in eight other littorinids: L. compressa, L. arcana, L. fabalis, Nodilittorina punctata, N trochoides, N. radiata, Littoraria undulata and Littoraria cingulifera. Using native Polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF) we compared the Mb and soluble protein (SP) profiles of these species. This suggested that: (1) L. saxatilis and L. arcana may have specific Mb/SP profiles, (2) Littoraria spp., Nodilittorina spp. and L. striata share similar Mb patterns, (3) Mb is remarkably diverse in the genus Littorina, (4) L. littorea shows intraspecific Mb/SP variation, (5) L. saxatilis does not show geographic Mb/SP differences, and (6) IEF uncovers substantial hidden Mb/SP heterogeneity not shown by PAGE (particularly for Melarhaphe neritoides). Hence, littorinid Mb/SP may be a useful taxonomic marker whose ecophysiological significance deserves further study, even if its genetic basis remains unclear.