Surprising similarity of sneaking rates and genetic mating patterns in two populations of sand goby experiencing disparate sexual selection regimes

Abstract

Molecular markers have proved extremely useful in resolving mating patterns within individual populations of a number of species, but little is known about how genetic mating systems might vary geographically within a species. Here we use microsatellite markers to compare patterns of sneaked fertilization and mating success in two populations of sand goby (Pomatoschistus minutus) that differ dramatically with respect to nest-site density and the documented nature and intensity of sexual selection. At the Tvärminne site in the Baltic Sea, the microsatellite genotypes of 17 nest-tending males and mean samples of more than 50 progeny per nest indicated that approximately 35% of the nests contained eggs that had been fertilized by sneaker males. Successful nest holders mated with an average of 3.0 females, and the distribution of mate numbers for these males did not differ significantly from the Poisson expectation. These genetically deduced mating-system parameters in the Tvärminne population are remarkably similar to those in sand gobies at a distant site adjoining the North Sea. Thus, pronounced differences in the ecological setting and sexual selection regimes in these two populations have not translated into evident differences in cuckoldry rates or other monitored patterns of male mating success. In this case, the ecological setting appears not to be predictive of alternative male mating strategies, a finding of relevance to sexual selection theory.

Consistent social structure within aggregations of the Australian lizard, Egernia stokesii across seven disconnected rocky outcrops

“…For example, Waterman and Fenton (2000) reported the social structure of Cape ground squirrels was stable over dramatic changes in resource availability and suggested that the benefits of group structure in defence against predators were more important than resource competition. Similarly, Yeager (1995) reported very similar social structure in proboscis monkey populations across a wide range of geographic locations and ecological circumstances, and Jones et al (2001) observed two sand goby populations in very different ecological circumstances but with similar mating systems.…”

Multiple male reproductive morphs in the invasive round goby (Apollonia melanostoma)

“…Iguchi et al (2004) reported evidence for an escalation of male-male competition, in invasive versus native populations of smallmouth bass (Micropterus dolomieu), possibly due to heightened competition for nest sites in the new habitats. However, when Jones et al (2001) examined sneaking rates in two sand goby populations, one with high and one with low nest densities, they found no difference in rates of sneaking. The degree of sexual selection itself rather than nest density per se (as one contributor to sexual selection) may be the factor that will select for increased alternative male reproductive behaviour.…”

Small-scale clinal variation, genetic diversity and environmental heterogeneity in the marine gobies Pomatoschistus minutus and P. lozanoi (Gobiidae, Teleostei)

“…Gobies of the genus Pomatoschistus (Gill) are among the most abundant fish species along the northeastern Atlantic coasts and have been widely used in ecological, evolutionary and behavioural studies (Fonds, 1973;Pampoulie et al, 1999;Jones et al, 2001). An electrophoretic survey of Atlantic and Mediterranean members of the genus Pomatoschistus occurring in habitats with a different degree of heterogeneity showed a positive correlation between the level of genetic variation within species and the degree of heterogeneity of the habitat in which each species preferentially occurs (Wallis and Beardmore, 1984a).…”