Evidence of Holarctic distribution: common frog Rana temporaria eggs in Fennoscandia host photosymbiotic green algae (Oophila sp.)

Abstract

Symbiosis is a commonly occurring phenomenon, with most plants and animals being holobionts, comprising of a host and its corresponding symbionts. It is, however, less common to have a symbiont only under a specific life stage and even more so between a photosynthesizing organism and a vertebrate animal. One such relationship is found between the unicellular green algae Oophila amblystomatis and the North American yellow-spotted salamander Ambystoma maculatum, which is so far the only known endosymbiotic relationship between an alga and a vertebrate. In this study we investigate the possible occurrence of O. amblystomatis in Fennoscandian egg clutches from the genus Rana using citizen science data. We establish that egg capsules of the common frog Rana temporaria in Sweden act as a host species for two subclades of the monophyletic genus Oophila on a microgeographical scale (< 10 km) using a phylogenetic analysis. Furthermore, we investigated a possible endosymbiotic relationship between O. amblystomatis and R. temporaria embryos with fluorescence microscopy, which showed no algal invasion of frog tissue or cells in vivo. The association with a known symbiont Oophila may hold ecological importance for ontogeny, individual fitness, behavior, population dynamics and evolutionary potential of R. temporaria. However, the reciprocal benefits to both partners have not been determined for any Oophila-bearing ranid. We discuss the possible Holarctic distribution of Oophila and consider the implications of the relationship between R. temporaria and O. amblystomatis.

Keywords

algae; amphibia; frog; Oophila amblystomatis; photosymbiosis; Rana temporaria

Published in

Oikos
2025
Publisher: WILEY

SLU Authors

• Eriksson, Pontus F.

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • University of Agder

• Laugen, Ane

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • University of Agder

UKÄ Subject classification

Ecology

Publication identifier

• DOI: https://doi.org/10.1111/oik.10752

Permanent link to this page (URI)

https://res.slu.se/id/publ/140934