Incorporating Phylogeography and SDM Projection to Inform Conservation Efforts of the Foundation Seaweed Gloiopeltis furcata sensu lato in the North Pacific Under Climate Change.

Understanding the impact of past climate events on population genetic structuring and range shifts may facilitate predictions of how species will respond to future climate change. Such integrative effort, however, remain rare for the North Pacific benthic ecosystem. Here, we obtained mtDNA cox1 and cpDNA rbcL sequences of 85 populations of the foundation macroalga Gloiopeltis furcata sensu lato (s.l.) in the North Pacific to estimate its lineage structuring and phylogeographic connectivity. We found that G. furcata s.l. harbored high and cryptic lineage diversity, and its present-day biogeographic patterns are mostly attributed to extensive vicariance and ocean-currents mediated dispersal events. In particular, the southwestern Japanese Archipelago and southern Korea potentially served as the center of ancestral persistence during the maximum ice sheet expansion, characterized by concurrent demographic contractions of lineages. We further applied projection-based species distribution models (SDMs) and detected consistent habitat suitability contraction in low latitude regions (20°N-40°N) (e.g., the Bohai Sea, the southern East China Sea, the southern Japan-Pacific coastline) and expansion in high latitude regions (40°N-60°N) (e.g., the southern Sakhalin Island, the northern Sea of Japan, the southern Kamchatka Peninsula and the Alaska Peninsula) under future moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios. These results demonstrate that integrating phylogeographic information (e.g., the identification of ancestral persistence areas and unique populations harboring rare allelic variation or high endemism) with SDMs-based assessments of climate change impacts, offers a powerful framework for prioritizing conservation units in marine benthic ecosystems under future climate change.