Presentation Title

Pulling your weight: do male Northern Pipefish (Syngnathus fuscus) contribute more to pregnancy than females?

Faculty Mentor

Tony Wilson

Start Date

23-11-2019 10:00 AM

End Date

23-11-2019 10:45 AM

Location

111

Session

poster 3

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Sexual selection is the selection of traits through competition for and the acquisition of mates. Relative parental investment is thought to be an important determinant of the direction of sexual selection. Males often solely contribute inexpensive sperm, while females invest energy-rich eggs and often provide post-fertilization care. In almost all vertebrates, females are the limiting sex and exert male choice, while males are ornamented and compete for mating opportunities. Members of the Syngnathidae (seahorse, pipefish, pipe dragons, and seadragons) family offer a unique system for exploring theories of sexual selection in a group in which males have evolved a specialized brooding organ and females often compete for access to mates. While male pregnancy is a highly specialized form of reproduction, the full extent of male reproductive investment in this group remains unclear. The Northern Pipefish species (Syngnathus fuscus) was used as a model to test how relative parental investment influences the direction of sexual selection. We first quantified female investment in the dry weight of eggs and tested for a positive relationship between female size and egg size. Secondly, male investment in offspring growth was measured as the dry weight of newly released offspring post 20-24 days of development. We found a significant relationship between female standard length and the dry weight of eggs, indicating that female size is an important determinant of female parental investment. We found that female investment in gametes significantly exceeds that of males but found preliminary evidence that the patrotrophic index of S. fuscus (0.85) exceeds that of purely lecithotrophic species, suggesting that males are actively contributing to offspring during pregnancy. Quantifying additional sources of male parental investment in this species will be needed to determine how relative parental investment influences the direction of sexual selection in S. fuscus.

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Nov 23rd, 10:00 AM Nov 23rd, 10:45 AM

Pulling your weight: do male Northern Pipefish (Syngnathus fuscus) contribute more to pregnancy than females?

111

Sexual selection is the selection of traits through competition for and the acquisition of mates. Relative parental investment is thought to be an important determinant of the direction of sexual selection. Males often solely contribute inexpensive sperm, while females invest energy-rich eggs and often provide post-fertilization care. In almost all vertebrates, females are the limiting sex and exert male choice, while males are ornamented and compete for mating opportunities. Members of the Syngnathidae (seahorse, pipefish, pipe dragons, and seadragons) family offer a unique system for exploring theories of sexual selection in a group in which males have evolved a specialized brooding organ and females often compete for access to mates. While male pregnancy is a highly specialized form of reproduction, the full extent of male reproductive investment in this group remains unclear. The Northern Pipefish species (Syngnathus fuscus) was used as a model to test how relative parental investment influences the direction of sexual selection. We first quantified female investment in the dry weight of eggs and tested for a positive relationship between female size and egg size. Secondly, male investment in offspring growth was measured as the dry weight of newly released offspring post 20-24 days of development. We found a significant relationship between female standard length and the dry weight of eggs, indicating that female size is an important determinant of female parental investment. We found that female investment in gametes significantly exceeds that of males but found preliminary evidence that the patrotrophic index of S. fuscus (0.85) exceeds that of purely lecithotrophic species, suggesting that males are actively contributing to offspring during pregnancy. Quantifying additional sources of male parental investment in this species will be needed to determine how relative parental investment influences the direction of sexual selection in S. fuscus.