Evidence for high rates of in-pair paternity in the socially monogamous snapping shrimp Alpheus angulosus

Abstract

Understanding the relationships between social and genetic interactions among individ- uals can lead to important insights into both the evolution of social behavior and the movement of alleles among generations. However, socially monogamous behavior is not always a good predictor of genetic parentage, so that inferences into genetic relationships among family group members require molecular genetic investigation. In the speciose snapping shrimp genera, social monogamy is the most common social system. However, research into mating and parentage relationships between socially monogamous partners has been limited by the reclusive nature of most snapping shrimp, which makes them difficult to observe under natural conditions, and so the degree to which social monogamy correlates with genetic monogamy remains unknown. Here, using data from 5 polymor- phic microsatellite markers, evidence for high rates (≥94% of offspring genotyped) of in-pair pater- nity in field-captured heterosexual pairs of Alpheus angulosus, a common intertidal alpheid, is reported. Therefore, male social partners were apparently the sole or primary fathers of their female partners' clutches in all pairs. Some clutches showed evidence of 3+ paternal alleles at one of the genotyped loci, which may be a signal of multiple paternity; however, in these cases, the possibility of genotyping errors cannot be discounted. In summary, these data indicate that social monogamy correlates closely with genetic monogamy in this taxon, though additional work is required in order to draw strong inferences about the occurrence of multiple paternity of individual clutches.