Island and Rensch’s rules do not apply to cave vs. surface populations of Asellus aquaticus

Frontiers in Ecology and Evolution

Ecology and Evolution

Žiga Fišer¹  Cene Fišer¹  Gergely Balázs²  Gábor Herczeg²  Anna Biró³  Simona Kralj-Fišer⁴ 

[1] Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia;ELKH-ELTE-MTM Integrative Ecology Research Group, Budapest, Hungary;Department of Systematic Zoology and Ecology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary;ELKH-ELTE-MTM Integrative Ecology Research Group, Budapest, Hungary;Department of Systematic Zoology and Ecology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary;Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary;Research Centre of the Slovenian Academy of Sciences and Arts, Jovan Hadži Institute of Biology, Ljubljana, Slovenia;

关键词: competition;    body size;    isopod;    predation;    sexual size dimorphism;    adaptation;    evolution;   

DOI  :  10.3389/fevo.2023.1155261

 received in 2023-01-31, accepted in 2023-04-13,  发布年份 2023

来源: Frontiers

【 摘 要 】

Body size is a trait of fundamental ecological and evolutionary importance that is often different between males and females (sexual size dimorphism; SSD). The island rule predicts that small-bodied species tend to evolve larger following a release from interspecific competition and predation in insular environments. According to Rensch’s rule, male body size relative to female body size increases with increasing mean body size. This allometric body size – SSD scaling is explained by male-driven body size evolution. These ecogeographical rules are rarely tested within species, and has not been addressed in a cave–surface context, even though caves represent insular environments (small and isolated with simple communities). By analyzing six cave and nine surface populations of the widespread, primarily surface-dwelling freshwater isopod Asellus aquaticus with male-biased SSD, we tested whether cave populations evolved larger and showed higher SSD than the surface populations. We found extensive between-population variation in body size (maximum divergence being 74%) and SSD (males being 15%–50% larger than females). However, habitat type did not explain the body size and SSD variation and we could not reject isometry in the male–female body size relationship. Hence, we found no support for the island or Rensch’s rules. We conclude that local selective forces stemming from environmental factors other than island vs. mainland or the general surface vs. cave characteristics are responsible for the reported population variation.

【 授权许可】

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Copyright © 2023 Herczeg, Balázs, Biró, Fišer, Kralj-Fišer and Fišer.