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Limited divergent adaptation despite a substantial environmental cline in wild pea
Author(s) -
Hellwig Timo,
Abbo Shahal,
Sherman Amir,
Coyne Clarice J,
Saranga Yehoshua,
LevYadun Simcha,
Main Dorrie,
Zheng Ping,
Ophir Ron
Publication year - 2020
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.15633
Subject(s) - cline (biology) , biology , gene flow , isolation by distance , population , ecology , genetic drift , genetic diversity , genetic structure , evolutionary biology , genetic divergence , adaptation (eye) , effective population size , gene pool , population size , genetic variation , genetics , demography , neuroscience , sociology , gene
Abstract Isolation by environment (IBE) is a widespread phenomenon in nature. It is commonly expected that the degree of difference among environments is proportional to the level of divergence between populations in their respective environments. It is therefore assumed that a species' genetic diversity displays a pattern of IBE in the presence of a strong environmental cline if gene flow does not mitigate isolation. We tested this common assumption by analysing the genetic diversity and demographic history of Pisum fulvum , which inhabits contrasting habitats in the southern Levant and is expected to display only minor migration rates between populations, making it an ideal test case. Ecogeographical and subpopulation structure were analysed and compared. The correlation of genetic with environmental distances was calculated to test the effect of isolation by distance and IBE and detect the main drivers of these effects. Historical effective population size was estimated using stairway plot. Limited overlap of ecogeographical and genetic clustering was observed, and correlation between genetic and environmental distances was statistically significant but small. We detected a sharp decline of effective population size during the last glacial period. The low degree of IBE may be the result of genetic drift due to a past bottleneck. Our findings contradict the expectation that strong environmental clines cause IBE in the absence of extensive gene flow.