The relationship between sex change and reproductive success in a protandric marine gastropod

Abstract

Protandric species switch sex during their lifetime. According to theory, the time (body size) at which sex change occurs is determined by the reproductive success of individuals affected by social interactions as well as by post-copulatory factors. Experimental evidence is biased to few social systems making the exploration of general patterns difficult. We used the protandric marine gastropod Crepidula coquimbensis that partakes in intrabrood sibling cannibalism to test the following hypotheses: 1. Male-male competition for access to females and sibling cannibalism determine male reproductive success; 2. Males with greater access to females and with higher reproductive success will have reduced growth rates and will delay sex change. Artificial aggregations with different social structures were constructed and male reproductive success was estimated by paternity analysis. The results supported our expectations showing that male competitive ability for access to the female, time spent by males in the copulatory position, and sibling cannibalism affect reproductive success and influence time to sex change, with less successful males hastening sex change. Also, males that spent more time in the copulatory position had reduced growth rates. Comparing these results with those reported for other sequential hermaphrodites provides evidence supporting general patterns of sex change in nature.

Sexual antagonism in sequential hermaphrodites

“…Moreover, alongside social interactions determining sex change, such sexually antagonistic fitness effects may also manifest through social interactions, and thus have more complex dynamics if they involve either siblings (e.g. sib-cannibalism in Crepidula coquimbensis (Brante et al 2016)), or mates (e.g. sexual conflict (Schärer et al 2015)).…”

Social regulation of reproduction: control or signal?

“…In other protandrous species, sex change is often regulated by body size and/or population sex ratio (Table 2). Individuals of male-first sex-changers can also delay sex change if they are obtaining high reproductive success as males (e.g., the slipper snail Crepidula [75]).…”

Characterization of a sex-determining region and its genomic context via statistical estimates of haplotype frequencies in daughters and sons sequenced in pools

“…Despite gonochorism being common and ancient, the mechanisms initiating the developmental cascade toward the male or female phenotype appear to be highly variable (BACHTROG et al 2014; BEUKEBOOM AND PERRIN 2014). In some species, sex is solely or partially determined by environmental factors such as temperature (MERCHANT-LARIOS AND DIAZ-HERNANDEZ 2013) and social interactions (BRANTE et al 2016) while in many others, sex is entirely determined by genotype (review in BACHTROG et al (2014); BEUKEBOOM AND PERRIN (2014)).…”