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Demographically idiosyncratic responses to climate change and rapid Pleistocene diversification of the walnut genus Juglans (Juglandaceae) revealed by whole‐genome sequences
Author(s) -
Bai WeiNing,
Yan PengCheng,
Zhang BoWen,
Woeste Keith E.,
Lin Kui,
Zhang DaYong
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14917
Subject(s) - coalescent theory , biology , juglans , population , evolutionary biology , temperate climate , most recent common ancestor , ecology , biological dispersal , effective population size , phylogenetic tree , phylogenetics , demographic history , botany , genetic variation , genetics , gene , demography , sociology
Summary Whether species demography and diversification are driven primarily by extrinsic environmental changes such as climatic oscillations in the Quaternary or by intrinsic biological interactions like coevolution between antagonists is a matter of active debate. In fact, their relative importance can be assessed by tracking past population fluctuations over considerable time periods. We applied the pairwise sequentially Markovian coalescent approach on the genomes of 11 temperate Juglans species to estimate trajectories of changes in effective population size ( N e ) and used a Bayesian‐coalescent based approach that simultaneously considers multiple genomes ( G‐PhoCS ) to estimate divergence times between lineages. N e curves of all study species converged 1.0 million yr ago, probably reflecting the time when the walnut genus last shared a common ancestor. This estimate was confirmed by the G‐Pho CS estimates of divergence times. But all species did not react similarly to the dramatic climatic oscillations following early Pleistocene cooling, so the timing and amplitude of changes in N e differed among species and even among conspecific lineages. The population histories of temperate walnut species were not driven by extrinsic environmental changes alone, and a key role was probably played by species‐specific factors such as coevolutionary interactions with specialized pathogens.