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Cutting-edge evolution of insects: factors governing
ecological divergence of natural populations assessed using
molecular and genetic markers
Published as a special issue of Insects (journal)
Editor-in-Chief: Hugh D. Loxdale
Natural insect populations are always likely to diverge ecologically under the influences of
selection, competition for scarce resources, both intra- and interspecific, including intra- and
interclonal in predominantly asexual insects, and genetic drift. This may arise by allopatric,
parapatric or sympatric means. In the case of the last, even though individuals are contiguous
within a population, divergence can arise by chromosomal means ‒ for example
complementary and non-complementary regions of the genome where genetic exchange can
or cannot occur; fusions and fissions, especially translocations; rearrangements such as
inversion polymorphisms brought about by transposon-induced ‘hot-spots’; mutation of sex
determining genes causing asexual populations, as in aphids; possibly mutualistic symbionts
leading to unique specialised host insect populations; sexual selection; and polyploidy ‒ to
name but the principle mechanisms. There are undoubtedly others, some as yet unknown. All
such mechanisms are liable to produce mutant individuals that can no longer interbreed with
the natal population, with divergence perhaps reinforced by chemical means, e.g.
kairomones, pheromones and cuticular hydrocarbons (CHCs), immune responses, as well as
in some species like cicadas, auditory mechanisms related directly to behaviour. In the
present collection of overview articles, various international experts in the field of molecular
ecology and genetics explore how insects have diverged and continue to do so at the
molecular-genetic level, sometimes rapidly, to become new ecological entities and thereby
new players in the great, ongoing panoply of evolution on Earth.