Article Title: Quaternary climatic oscillation promoted
speciation of two closely related endangered langurs (François’ langur
and White-headed langur)
Xinrui Li1, Dafu Ru1#, Zhixin
Zhang2, Paul A.
Garber3,4, Jianquan Liu1, Ming
Li5,6, Xumao Zhao1*
1 State Key Laboratory of Grassland Agro-Ecosystems,
Institute of Innovation Ecology, Lanzhou University, Lanzhou 730000,
China
2 Arctic Research Center, Hokkaido University,
Sapporo, 001-0021, Japan
3 Department of Anthropology and Program in Ecology
and Evolutionary Biology, University of Illinois, Urbana, Illinois,
61801, USA
4 International Centre of Biodiversity and Primate
Conservation, Dali University, Dali, Yunnan, China
5 CAS Key Laboratory of Animal Ecology and
Conservation Biology, Institute of Zoology, Chinese Academy of Sciences,
Chaoyang District, Beijing 100101, China
6 Center for Excellence in Animal Evolution and
Genetics, Chinese Academy of Sciences, Kunming 650223, China
# Contributed equally to this work.
* Correspondence:Xumao Zhao, State Key Laboratory of Grassland
Agro-Ecosystems, Institute of Innovation Ecology, Lanzhou University,
Lanzhou 730000, China
Email: zhaoxm@lzu.edu.cn
Running title: Climatic oscillation promoted speciation
Abstract : Climate
oscillations may drive the divergence of ancestral species through
habitat isolation, species distribution patterns, and the cessation of
gene flow. However, traditional ecological niche models lack the
consideration for the genetic adaptation of species, thus it’s difficult
to understand how climate oscillations affect species divergence by
changing their climatic suitability and historical demography. We
analyzed the impact of climate change on the divergence of two langur
species, François’ langur and White-headed langur, using Maxent,
Genotype–Environment Association (GEA) models and genomic data. Our
results indicate that 1) Climatic suitability for François’ langur and
White-headed langur has separated from the Last Interglacial (LIG,
120,000-140,000 years ago) to the Last Glacial Maximum (LGM); 2)
Although the effective population size for both species decreased
between the LIG and the LGM, the effective population size of François’
langur increased more quickly than that of White-headed langur from the
LGM to the present; 3) Historical patterns of climate change have
resulted in periods of expanded and contracted climatic suitability,
with each species experiencing periods of interspecific genetic
isolation and periods of interspecific genetic exchange; and 4) Human
activities and future climate change have contracted the range of
François’ langur (in China) and White-headed langur. Climate
oscillation, population isolation, and in situ evolution in refugia from
the LIG to the LGM appear to have played a critical role in langur
speciation and adaptive evolution. Overall, our results demonstrate how
climatic oscillations and historical demography drive speciation,
providing a new perspective on species divergence and conservation.
Keywords: Climatic oscillation, Climatic suitability,
François’ langur, Historical demography, Speciation, White-headed langur