Limited divergent adaptation despite a substantial environmental cline in wild pea

Isolation by environment (IBE) is a wide spread phenomenon in nature. It is commonly expected that the degree of differences among environments is proportional to the level of divergence between populations in these environments. Consequentially, it is assumed that species’ genetic diversity displays pattern of IBE in the presence of a strong environmental cline if geneflow does not mitigate isolation. We tested this common assumption by analyzing the genetic diversity and demographic history of Pisum fulvum. P. fulvum inhabits very contrasting habitats in the southern Levant and is expected to display only minor migration rates between populations what makes it an ideal test case. Ecogeographic and subpopulation structure was analyzed and compared. Correlation of genetic with environmental distances was calculated to test the effect of IBD and IBE and detect the main drivers of these effects. Historic effective population size was estimated using stairwayplots. Limited overlap of ecoge..., Plant material and habitat characteristics
Naim-Feil et al. (2017) collected 135 P. fulvum accessions spanning its documented ecological amplitude in Israel and the Palestinian Territories. Our collection was comprised of 126 of these accessions (Supplementary Table. S1). Within our study area, comprising Israel and the Palestinian Territories, it occupies a wide range of different habitats. In these habitats average temperature in the main growing season during winter ranges from 4.0°C to 14.3°C. The annual precipitation, which occurs almost entirely during the winter months, spans a range from 295 mm to 914 mm. The echo system of each sampling site, i.e., the climate conditions, soil content, and the vegetative vicinity is tabulated in Supplementary Table S1. For more detailed description of P. fulvum habitats see Abbo et al. (2013). We are unaware of published census size data for wild pea of which is rather difficult to assess. The number of individuals in a population strongly var...,