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A morphological cline in Eucalyptus : a genetic perspective
Author(s) -
Holman James E.,
Hughes Jane M.,
Fensham Rod J.
Publication year - 2003
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 - 10.1046/j.1365-294x.2003.01970.x
Subject(s) - cline (biology) , biology , allopatric speciation , evolutionary biology , hybrid zone , gene flow , isolation by distance , population , parapatric speciation , adaptation (eye) , genetic variation , genetics , gene , demography , neuroscience , sociology
The putative hybrid zone between Eucalyptus populnea and E. brownii is examined using morphological and molecular techniques. This species complex displays continuous morphological variation across the study area, which has been previously interpreted as the product of hybridization between allopatric species. A microsatellite analysis indicates that there was little genetic structuring across the morphological cline and only low levels of population differentiation. The nested clade analysis of the J LA+ region of the chloroplast DNA (cpDNA) indicates that the geographical distribution of cpDNA haplotypes is unlikely to be the result of historical hybridization events, and that restricted seed‐mediated gene flow with isolation by distance is responsible for the phylogeographical distribution. A more plausible explanation for the origin and persistence of the morphological cline is that the process of continuous morphological diversification has been promoted by a directional selection gradient. This study addresses species status within Eucalyptus and the belief that hybridization is widespread and is an important process in the group's evolution.