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1/6 This talk is about a recent paper ( @ASNAmNat 2020 https://www.journals.uchicago.edu/doi/abs/10.1086/707016?journalCode=an) with microeconomist G Nöldeke ( https://wwz.unibas.ch/en/prof-dr-georg-noeldeke/) and marine biologist O Puebla ( http://www.puebla-lab.org/ ). This was my main project while a postdoc at @GEOMAR_en back in 2016-2017. #AnimBehav2021
2/6 Egg trading (the exchange of eggs for fertilization by simultaneous hermaphrodites) is one of the most cited examples of reciprocity in animals (HT @LeeDugatkin https://www.google.co.uk/books/edition/_/hXQ8DwAAQBAJ?hl=en). Yet how egg trading may originate is unclear. #AnimBehav2021
3/6 We studied this with a game theory model that considers encounter rates and costs of egg production in a population with three types: traders ("offer eggs only to egg-carrying partners"), providers ("always offer eggs"), and withholders ("never offer eggs"). #AnimBehav2021
4/6 Our model extends Henshaw, @Mikejennions, and @kokkonutter (2014, https://doi.org/10.1007/s13235-014-0107-1) by adding 4 features: 1. we allow for withholders, 2. we add costs of egg production, 3. traders can detect withholders with some probability, 4. eggs can get rotten. #AnimBehav2021
5/6 Our results indicate that a combination of intermediate encounter rates, high costs of egg production (= low mating availability for individuals producing eggs), and high probability that traders detect withholders is conducive to the evolution of egg trading. #AnimBehav2021
6/6 Under these conditions, traders can invade and resist invasion from both providers and withholders. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of egg trading in simult hermaphrodites. #AnimBehav2021
