Biology Reference
In-Depth Information
13.7.6.5 Populations of
Aedes taeniorhynchus
in the Galapagos Islands: Rapid
Evolution of an Invasive Species
Aedes taeniorhynchus
is thought to have colonized the Galapagos Islands
≈
200,000 years ago. The islands in the Galapagos typically have coastal habitats
that are rocky and contain mangroves but have a very dry inland zone. Highlands
on the larger islands, such as Santa Cruz, obtain more rain and have a lush veg-
etation (
Bataille et al. 2010
).
Bataille et al. (2010)
used microsatellite data to com-
pare coastal and highland mosquito populations and to determine whether gene
flow is occurring between the two habitats. They discovered that the coastal
and highland populations were highly differentiated from each other all year
round, with some gene flow detected only during periods of increased precipi-
tation. The results support the hypothesis that selection, arising from ecological
differences between the two habitats, is driving adaptation and divergence in
A. taeniorhynchus
. Indeed, the authors speculated that the two populations on
Santa Cruz might represent an example of incipient speciation.
13.7.6.6 Industrial Melanism in Peppered Moths
Industrial melanism in the moth
Biston betularia
in nineteenth century Great
Britain is famous for illustrating a rapid evolutionary response to an altered
environment. The ancestral form of the peppered moth (
typica
) is white with
dark speckles but, after the Industrial Revolution, a darker form (
carbonaria
)
became more common due to natural selection in sooty environments. The
carbonaria
form displaced the light-colored moths in the polluted woodlands
of Europe, reportedly due to selective predation by birds on the lighter moths
when located on sooty trees (
Cook et al. 2012, Luiggi 2012
). The black form of
the moth was known to be due to a single-locus dominant allele, but the bio-
chemical basis of this phenotype remained unknown until
van't Hof et al. (2011)
mapped the melanism to a 200-kb region of a chromosome and further nar-
rowed it to a single nucleotide polymorphism (SNP) marker. Analyses of moths
from the field indicated that the same SNP marker is the basis of all
carbonaria
moths in the United Kingdom, and all are derived from a single ancestral hap-
lotype that “coincides with major wing-patterning loci in other lepidopteran
systems, suggesting the existence of basal color-patterning regulators in this
region.”
13.8 Applied Pest Management
Intraspecific variation and genetic changes in both pest and beneficial arthro-
pods influence pest management strategies and tactics in different ways. The
fact that pest and natural enemy populations change genetically has been
