Environmental Engineering Reference
In-Depth Information
individuals in the species (Harris and Pimm, 2008). For example, the whoop-
ing cranes (
Grus americana
) while on their wintering ground in Texas are
at high risk if there is an oil spill or powerful hurricane because the entire
population winters in a small inlet along the coast; (2) The overall popula-
tion size is small, which can be detrimental because breeding in a small
population can result in inbreeding (Liao and Reed, 2009). This, in turn, can
increase the expression of deleterious genes, which decreases the number
of fit young being produced, and the loss of genetic variability, which is
needed to allow adaptation to novel habitats; and (3) The population de-
pends on some factor or species that could be at risk from disturbances, such
as pollution, poaching, or climate change, among others. For example, the
red-cocked woodpecker (
Picoides borealis
) must nest in 70- to 120-year-
old pines, most of which in the late 1800s and mid 1900s were cut down
for various uses. Another example involves plant-eating insects, of which
there are estimated to be 213,830 to 547,500 species committed to extinc-
tion because the range of their host plants are shrinking in size because of
warming (Fonseca, 2009).
When climate change is one of the main forces acting on a species,
then distance to closest cool refuge (Figure 5.17) is also as important as
FIGURE 5.17 Map showing the distance to potential cool refuges, where cool is defined as the temperatures
in 2100 are equal to or cooler than the temperatures in the 1960s. Used 0.5 x 0.5 latitude-longitude blocks.
Source: Wright et al. (2009).
