Mating Behaviour of the Sperm Trading Sea Slug <i>Chelidonura hirundinina</i>: Repeated Sex Role Alternation Balances Reciprocity

Putz, Annika; Michiels, Nico K.; Anthes, Nils

doi:10.1111/j.1439-0310.2007.01440.x

Cited by 3 publications

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“…Mating descriptions were previously not available for most of the species analyzed in this study. However, the sexual behavior of four species has attracted recent attention in the context of hermaphrodite sexual behavior: Navanax inermis (see Leonard & Lukowiak 1984, 1985; Michiels et al 2003), C. sandrana (see Anthes & Michiels 2005; Anthes et al 2006a), Chelidonura hirundinina (see Anthes et al 2005; Putz et al in press), and Siphopteron quadrispinosum (see Anthes & Michiels 2007). Apart from these studies only a few taxonomic publications, regional species lists, and field observations collated in an Internet site (http://www.seaslugforum.net) contain anecdotal information on mating behavior.…”

Section: Methodsmentioning

confidence: 99%

Reproductive morphology, mating behavior, and spawning ecology of cephalaspid sea slugs (Aglajidae and Gastropteridae)

Anthes

Michiels

2007

Invertebrate Biology

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Several recent experimental studies have assessed the behavioral reproductive ecology of four opisthobranch species belonging to the families Aglajidae and Gastropter-idae (Cephalaspidea). In order to extend the scope of this earlier work, here we document the reproductive morphology and behavior of 36 taxa belonging to the same two sea slug families. Measurements focus on insemination patterns, spawning characteristics, as well as the size and shape of male and female reproductive organs (i.e., prostate, penis, bursa copulatrix, seminal receptacle). We found that behavioral and morphological traits vary considerably between species, even between closely related taxa. Mating behavior covers the full spectrum from unilateral to simultaneously reciprocal insemination and includes putatively antagonistic mechanisms such as hypodermic injection in some cases. With respect to morphology, particularly great variation was present in traits related to the male sexual function, such as prostate size and penis type. In traits associated with the female function, noticeable variation in those traits accessible for measurement was limited to the relative size of the sperm-digesting bursa copulatrix. These data provide the basis for future comparative analyses on the evolution of reproductive characters in a phylogenetic context. We further explore the relationship between characteristics and body size. Our data corroborate previous findings that in species with exclusively planktotrophic development, investment per embryo (using mean egg diameter per species as a proxy) is independent of mean species body size. In contrast to egg size, spawn weight and the number of eggs per spawn tightly increased with body size, both within and among species. Hence, larger individuals among planktotrophs increased reproductive investment by increasing offspring quantity rather than investing more into each single offspring. Comparably large eggs with few eggs per spawn in our only two species with facultatively intracapsular metamorphosis are also consistent with findings in other opisthobranchs.

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Section: Methodsmentioning

confidence: 99%

Reproductive morphology, mating behavior, and spawning ecology of cephalaspid sea slugs (Aglajidae and Gastropteridae)

Anthes

Michiels

2007

Invertebrate Biology

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Mate choice and reproductive conflict in simultaneous hermaphrodites

Anthes

2010

Animal Behaviour: Evolution and Mechanisms

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Sexual selection and sperm quantity: meta-analyses of strategic ejaculation

2011

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Multiple mating or group spawning leads to post-copulatory sexual selection, which generally favours ejaculates that are more competitive under sperm competition. In four meta-analyses we quantify the evidence that sperm competition (SC) favours greater sperm number using data from studies of strategic ejaculation. Differential investment into each ejaculate emerges at the individual level if males exhibit phenotypic plasticity in ejaculate properties in response to the likely risk and/or intensity of sperm competition after a given mating. Over the last twenty years, a series of theoretical models have been developed that predict how ejaculate size will be strategically adjusted in relation to: (a) the number of immediate rival males, with a distinction made between 0 versus 1 rival ('risk' of SC) and 1 versus several rivals ('intensity' of SC); (b) female mating status (virgin or previously mated); and (c) female phenotypic quality (e.g. female size or condition). Some well-known studies have reported large adjustments in ejaculate size depending on the relevant social context and this has led to widespread acceptance of the claim that strategic sperm allocation occurs in response to each of these factors. It is necessary, however, to test each claim separately because it is easy to overlook studies with weak or negative findings. Compiling information on the variation in outcomes among species is potentially informative about the relevance of these assumptions in different taxa or mating systems. We found strong evidence that, on average, males transfer larger ejaculates to higher quality females. The effect of female mating status was less straightforward and depended on how ejaculate size was measured (i.e. use of proxy or direct measure). There is strong evidence that ejaculate size increased when males were exposed to a single rival, which is often described as a response to the risk of SC. There is, however, no evidence for the general prediction that ejaculate size decreases as the number of rivals increases from one to several males (i.e. in response to a higher intensity of SC which lowers the rate of return per sperm released). Our results highlight how meta-analysis can reveal unintentional biases in narrative literature reviews. We note that several assumptions of theoretical models can alter an outcome's predicted direction in a given species (e.g. the effect of female mating status depends on whether there is first- or last-male sperm priority). Many studies do not provide this background information and fail to make strong a priori predictions about the expected response of ejaculate size to manipulation of the mating context. Researchers should be explicit about which model they are testing to ensure that future meta-analyses can better partition studies into different categories, or control for continuous moderator variables.

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Mating Behaviour of the Sperm Trading Sea Slug Chelidonura hirundinina: Repeated Sex Role Alternation Balances Reciprocity

Cited by 3 publications

References 25 publications

Reproductive morphology, mating behavior, and spawning ecology of cephalaspid sea slugs (Aglajidae and Gastropteridae)

Reproductive morphology, mating behavior, and spawning ecology of cephalaspid sea slugs (Aglajidae and Gastropteridae)

Mate choice and reproductive conflict in simultaneous hermaphrodites

Sexual selection and sperm quantity: meta-analyses of strategic ejaculation

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