Mate availability determines use of alternative reproductive phenotypes in hermaphrodites

Anja Felmy, Nora Weissert, Joseph Travis, Jukka Jokela

Research output: Contribution to journalArticlepeer-review


In many species, individuals can employ alternative reproductive phenotypes, with profound consequences for individual fitness and population dynamics. This is particularly relevant for self-compatible hermaphrodites, which have exceptionally many reproductive options. Here we investigated the occurrence of reproductive phenotypes in the simultaneously hermaphroditic freshwater snail Radix balthica under experimentally simulated conditions of low versus moderate population density. We captured all mating behavior on camera and measured individual female lifetime reproductive success. We found every possible reproductive phenotype: (1) both male and female (i.e., truly hermaphroditic) reproduction, (2) purely female and (3) purely male reproduction, (4) male reproduction combined with self-fertilization and (5) female mating activity, (6) pure self-fertilization without mating and (7–8) two types of reproductive failure. Variation in alternative reproductive phenotypes was explained by mate availability (10.8%) and individual condition, approximated by a snail’s mean daily growth rate (17.5%). Increased mate availability resulted in a lower diversity of reproductive phenotypes, in particular increasing the frequency of true hermaphrodites. However, it lowered phenotype-specific fecundities and hence reduced the population growth rate. Snails in better condition were more likely to reproduce as true hermaphrodites or pure females, whereas low-condition snails tended to suffer reproductive failure. Overall, we show substantial variation in alternative reproductive phenotypes in a hermaphrodite, which is possibly in part maintained by fluctuations in population density and thus mate availability, and by variation in individual condition. We also provide evidence of an almost 2-fold increase in clutch size that can be ascribed specifically to mating as a female.

Original languageEnglish
Pages (from-to)1003-1016
Number of pages14
JournalBehavioral Ecology
Issue number4
Publication statusPublished - 2020
Externally publishedYes

Bibliographical note

Funding Information:
Funding for conducting this research was provided by ETH Zurich, Switzerland. While completing this work, A.F. was funded by an Early Postdoc.Mobility Fellowship from the Swiss National Science Foundation (P2EZP3_181775).

Publisher Copyright:
© The Author(s) 2020. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.

Free keywords

  • Growth rate
  • Mate availability
  • Mating-system evolution
  • Mixed mating
  • Radix
  • Selfing
  • Simultaneous hermaphroditism


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