Thursday, February 18, 2021

[Ichthyology • 2021] Genome Sequences reveal Global Dispersal Routes and Suggest Convergent Genetic Adaptations in Seahorse Evolution

Genetic diversity and phylogenetic relationships of Hippocampus.

in Li, Olave, Hou, ... et Lin, 2021. 

Seahorses have a circum-global distribution in tropical to temperate coastal waters. Yet, seahorses show many adaptations for a sedentary, cryptic lifestyle: they require specific habitats, such as seagrass, kelp or coral reefs, lack pelvic and caudal fins, and give birth to directly developed offspring without pronounced pelagic larval stage, rendering long-range dispersal by conventional means inefficient. Here we investigate seahorses’ worldwide dispersal and biogeographic patterns based on a de novo genome assembly of Hippocampus erectus as well as 358 re-sequenced genomes from 21 species. Seahorses evolved in the late Oligocene and subsequent circum-global colonization routes are identified and linked to changing dynamics in ocean currents and paleo-temporal seaway openings. Furthermore, the genetic basis of the recurring “bony spines” adaptive phenotype is linked to independent substitutions in a key developmental gene. Analyses thus suggest that rafting via ocean currents compensates for poor dispersal and rapid adaptation facilitates colonizing new habitats.

Fig. 1: Genetic diversity and phylogenetic relationships of 358 seahorse specimens.

Independent evolution in the phylogenetic tree reconstructed for the protein encoded by bmp3. Seahorses illustrations by Geng Qin.

Chunyan Li, Melisa Olave, Yali Hou, Geng Qin, Ralf F. Schneider, Zexia Gao, Xiaolong Tu, Xin Wang, Furong Qi, Alexander Nater, Andreas F. Kautt, Shiming Wan, Yanhong Zhang, Yali Liu, Huixian Zhang, Bo Zhang, Hao Zhang, Meng Qu, Shuaishuai Liu, Zeyu Chen, Jia Zhong, He Zhang, Lingfeng Meng, Kai Wang, Jianping Yin, Liangmin Huang, Byrappa Venkatesh, Axel Meyer, Xuemei Lu and Qiang Lin. 2021. Genome Sequences reveal Global Dispersal Routes and Suggest Convergent Genetic Adaptations in Seahorse Evolution. Nature Communications. 12, 1094. DOI: 10.1038/s41467-021-21379-x