Abstract

Three populations of Archachatina marginata snails (P₁, P₂ and P₃) obtained from natural snail habitats located in three states of Nigeria (one population per state) namely Enugu, Edo and River States were evaluated for pre-mating reproductive isolation using mate-choice tests. Total number of mated snails were very small (19.2%) compared to the number tested. Mating propensity (MP) varied significantly (P ≤ 0.05) among snail populations in two test groups and observed MP in the test groups differed significantly (chi-square test, P 0.05; 0.001) from that expected under random mating. Pair formation was significantly (chi-square test, P  0.05; 0.001) influenced by differences in MP and within-population (homotypic) and between population (heterotypic) mating occurred in frequencies that differed significantly (chi-square test, P Ë‚ 0.05; 0.001) from that expected under random mating. Whereas observed heterotypic pair formation were less than that expected under random mating, homotypic pair formation were either equal or more than that expected under random mating. Duration of reproductive activities differed significantly (P ≤ 0.05) among test populations. It was concluded that reduced pair formation, elongated duration of courtship, and reduced mating between populations of A. marginata, indicate partial or incomplete pre-mating reproductive isolation.

Key words: Pre-mating isolation, mating propensity, mating duration, homotypic mating, heterotypic mating.