Download Prof. Abraham Korol, University of Haifa, Israel

Variation of recombination at the genome, organism and species levels
Abraham B. Korol
Institute of Evolution, University of Haifa, Haifa 31905, Israel, [email protected]
Abundant evidence suggests high variation in parameters characterizing recombination frequency and
genomic distribution. This variation can depend on the target DNA sequence, genotype, sex, age, and
environment. Although it is generally accepted that recombination is a major source of heritable variation for
selection to act upon, the significance of variability of recombination itself and of the majority of its other
features remain unknown. Nor are the possible reasons for evolving and maintaining these features clear. This
concerns such properties as non-uniformity of exchanges per unit physical length (between-segment
differences of 1 to 2 orders of magnitude), a broad range of cM/Mb variation among eukaryotes, the ubiquity
of genetic interference, high intraspecific polymorphism and non-heritable variability of recombination
parameters, etc. In view of this, two groups of interrelated questions of fundamental importance for
understanding the problem of heredity in general can be recognized: (a) Are the recombination properties
observed in extant species of any functional significance for population adaptation and evolution as well as
for breeding programs? (b) Can these properties be assumed to have spread and become established due to the
fact that they improve the efficiency of transformations of genetic variability available for selection or are
they a by-product of evolutionary processes not associated directly with combinative functions of
recombination (processes which have determined the formation of sexual reproduction, DNA replication and
repair, as well as the genome structure)? A positive response to these questions seems to be a reasonable
hypothesis that fits the available evidence. The lecture is an attempt to illustrate this point.