Convergent evolution of kidney sizes and supraorbital salt glands for birds living in saline habitats

Chi-Cheng Chiu; Cheng-Te Yao; Ben-Yang Liao; Shou-Hsien Li

doi:10.1016/j.isci.2024.109169

Convergent evolution of kidney sizes and supraorbital salt glands for birds living in saline habitats

iScience. 2024 Feb 9;27(3):109169. doi: 10.1016/j.isci.2024.109169. eCollection 2024 Mar 15.

Authors

Chi-Cheng Chiu¹, Cheng-Te Yao², Ben-Yang Liao³, Shou-Hsien Li¹

Affiliations

¹ School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan.
² High altitude research station, Taiwan Endemic Species Research Institute, Nantou 55244, Taiwan.
³ Institute of Population Health Sciences, National Health Research Institutes, Zhunan 350, Taiwan.

Abstract

Only a small number of avian species inhabit salty environments. To understand how they adapted, we examined the evolution of kidney sizes, supraorbital salt glands (SSGs), and the utilization of salty habitats across 230 species spanning 25 avian orders. Phylogenetic analysis indicates that SSGs, large kidneys, and thriving in salty habitats emerged convergently in birds. Transition rate analysis reveals that species possessing SSGs and large kidneys tended to move from low-to high-salinity environments, while others moved in the opposite direction. However, habitat salinity also influenced kidney evolution; lineages residing in high-salinity environments tended to develop larger kidneys than those in low-salinity environments. Our findings suggest that SSGs and large kidneys may have evolved through adaptation to high salinity. Overall, habitat conditions and physiological traits influenced avian adaptation to salty environments in a reciprocal manner. These results shed the new light on the evolutionary mechanisms underlying functional diversity in birds.

Keywords: Evolutionary biology; Ornithology; Phylogeny.