Limited divergent adaptation despite a substantial environmental cline in wild pea

Timo Hellwig, Shahal Abbo, Amir Sherman, Clarice J. Coyne, Yehoshua Saranga, Simcha Lev-Yadun, Dorrie Main, Ping Zheng, Ron Ophir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


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.

Original languageAmerican English
Pages (from-to)4322-4336
Number of pages15
JournalMolecular Ecology
Issue number22
StatePublished - 1 Nov 2020

Bibliographical note

Publisher Copyright:
© 2020 John Wiley & Sons Ltd


  • demographic history
  • divergent adaptation
  • genetic diversity
  • isolation by distance
  • isolation by environment


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