Climate change drives corals to switch algal symbiotic partners at the forefront of northward migration

Coral reef ecosystems harbor high biodiversity, yet corals are increasingly threatened by elevated water temperatures due to climate change. Interestingly, several coral species are expanding their distributions northward into temperate areas of Japan. These recently colonized marginal populations may experience harsh environmental conditions, potentially resulting in reduced allelic and/or heterozygosity-based genetic diversity. However, they may also exhibit unique adaptive strategies in both corals and symbionts, exemplified by shifts in symbiont type. In this study, we tested these hypotheses by assessing the genetic diversity and connectivity of the corals and their symbiotic Symbiodiniaceae.