Native oak chloroplasts reveal an ancient divide across Europe

Authors


  • During the study period, Colin Ferris was a postdoctoral researcher funded by NERC but has now moved to an academic post at Leicester University. The work is a result of the collaboration between population geneticists, molecular biologists and plant ecologists in the Population Biology Sector at UEA, aiming to study the postglacial history of key species using molecular techniques. The project forms part of a continuing study of the geographical subdivision of species, particularly in Europe, including two grasshopper species, trees and toads.

Abstract

Glacial refugia and postglacial migration are major factors responsible for the present patterns of genetic variation we see in natural populations. Traditionally postglacial history has been inferred from fossil data, but new molecular techniques permit historical information to be gleaned from present populations. The chloroplast tRNALeu1 intron contains regions which have been highly conserved over a billion years of chloroplast evolution. Surprisingly, in one of these regions which has remained invariant for all photosynthetic organisms so far studied, we have found intraspecific site polymorphism. This polymorphism occurs in two European oaks, Quercus robur and Q. petraea, indicating hybridisation and introgression between them. Two distinct chloroplast types occur and are distributed geographically as eastern and western forms suggesting that these oaks are each derived from at least two separate glacial refugia.

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