Table 1

Factors potentially influencing distribution of genetic variation across species ranges, their expected effect on genetic variability and the acting population processes.

Factor

Expected effect on genetic variability in affected populations

Population process


Geographic marginality

negative

Drift by increased population turn-over and low population density because of unfavourable environmental conditions

Gene-flow

positive

Gene-flow counteracts the effects of drift

Mixed mating system

negative

Selfing decreases effective population size and thus increases drift

Environmental marginality

negative

Drift by increased population turn-over and low population density because of unfavourable environmental conditions

Biotic interactions

negative

or

positive

Drift by increased population turn-over due to interspecific competition

Introgression of alleles from related species by hybridisation

Dispersal barriers

positive

Accumulation of immigrating alleles

Range expansions

negative

Drift due to founder effects, bottlenecks or allele surfing

Population fragmentation

negative

Drift due to diminished effective population size

Secondary contact

positive

Mixing of alleles that evolved in isolation


Pfenninger et al. BMC Evolutionary Biology 2011 11:135   doi:10.1186/1471-2148-11-135

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