Heterosis and inbreeding depression in bottlenecked populations: a test in the hermaphroditic freshwater snail Lymnaea stagnalis

• Published in: Journal of evolutionary biology Vol. 24; no. 10; pp. 2248 - 2257
• Main Authors: COUTELLEC, M.‐A., CAQUET, T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2011; Wiley
• Subjects: Animals; deleterious mutations; Freshwater; Freshwater ecology; Hermaphroditic Organisms - genetics; heterosis; Hybrid Vigor; Inbreeding; inbreeding depression; Life Sciences; Lymnaea - genetics; Lymnaea - physiology; Lymnaea stagnalis; mating system; Mollusks; population bottleneck; Population Dynamics; selfing; Sexual Behavior, Animal; Lymnaea stagnalis; selfing; mating system; population bottleneck; heterosis; deleterious mutations; inbreeding depression
• ISSN: 1010-061X; 1420-9101
• DOI: 10.1111/j.1420-9101.2011.02355.x

Small population size is expected to induce heterosis, due to the random fixation and accumulation of mildly deleterious mutations, whereas within‐population inbreeding depression should decrease due to increased homozygosity. Population bottlenecks, although less effective, may have similar consequences. We tested this hypothesis in the self‐fertile freshwater snail Lymnaea stagnalis, by subjecting experimental populations to a single bottleneck of varied magnitude. Although patterns were not strong, heterosis was significant in the most severely bottlenecked populations, under stressful conditions. This was mainly due to hatching rate, suggesting that early acting and highly deleterious alleles were involved. Although L. stagnalis is a preferential outcrosser, inbreeding depression was very low and showed no clear relationship with bottleneck size. In the less reduced populations, inbreeding depression for hatching success increased under high inbreeding. This may be consistent with the occurence of synergistic epistasis between fitness loci, which may contribute to favour outcrossing in L. stagnalis.