title: Effects of age, size, and mating history on sex role decision of a simultaneous hermaphrodite.
abstract: Contrasting with separate-sexed animals, simultaneous hermaphrodites display unique reproductive strategies as they are male and female at the same time. Simultaneous hermaphrodites that copulate unilaterally, for instance, make a decision to mate as a male or female. Previous studies have demonstrated that sex role preference in hermaphrodites is flexible and is controlled by several, often confounding, factors. We examined the relationship between sex role decisions and 3 life-history traits (age, size, and mating history) in the great pond snail,Lymnaea stagnalis. Based on our field observations, which indicate that adult individuals show overlapping generations and large variation in body size during the breeding season, we performed a sex role choice experiment in the laboratory. We found that young and small snails mate as males first. Both age and size significantly affected sex role decision, with age having a stronger effect. Furthermore, we tested whetherL. stagnalisbecomes reluctant to inseminate a mate after being inseminated because it is known that after insemination, male investment substantially reduces. Contrary to expectations, our results indicate that the receipt of seminal fluid does not seem to reduce male motivation. In sum, sex role decisions inL. stagnalisare largely determined by age and size but not by having received seminal fluid. This mating pattern, however, does not fully support the size-advantage model because large or old individuals did not perform better as females in our experiment. These results imply a conflicting mating interest, rather than harmonious agreement, between age- and size-different hermaphrodites.
authors.affiliation: Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands .
authors.forename: Yumi
authors.initials: Y
authors.lastname: Nakadera
authors.affiliation: Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands .
authors.forename: Elferra M
authors.initials: EM
authors.lastname: Swart
authors.affiliation: Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands , ; Applied Biology, HAS University of Applied Sciences , Onderwijsboulevard 221, 5223DE 's-Hertogenbosch , The Netherlands , and.
authors.forename: Jeroen P A
authors.initials: JP
authors.lastname: Maas
authors.affiliation: Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands .
authors.forename: Kora
authors.initials: K
authors.lastname: Montagne-Wajer
authors.affiliation: Behavioural Neurobiology, Max Planck Institute for Ornithology , Eberhard-Gwinner-Strasse, 82319 Seewiesen , Germany.
authors.forename: Andries
authors.initials: A
authors.lastname: Ter Maat
authors.affiliation: Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands .
authors.forename: Joris M
authors.initials: JM
authors.lastname: Koene
keywords: Lymnaea stagnalis; reproductive strategy; sex allocation; sexual conflict; size-advantage model.