Biology Reference
In-Depth Information
region of the Old World have shown earlier flowering by 14-24 days
(Peñuelas et al. 2002).
Analysis of the harmful alien plants and animals that have invaded the
United States indicates that about 48% are likely to expand their ranges
northward in response to climatic warming (Zavaleta and Royval 2002).
An increase of mean annual temperature of 1°C, for example, is projected
to enable the imported red fire ant (
Solenopsis wagneri
) to expand its range
by more than 23%, including much of the states of Virginia and Ten-
nessee. Drier and warmer conditions would allow salt cedar (
Tamarix
spp.)
to spread into many areas now too humid for the species. Similar predic-
tions of expansion of alien species have been formulated in Europe, Aus-
tralia, New Zealand, and other areas. Similarly, several tropical diseases of
humans are likely to expand into presently temperate regions.
Evolutionary Adaptation to Changing
Global Climate
Several studies have shown rapid evolution in characteristics of insects
whose ranges are spreading northward in response to climatic warming.
In chapter 2, we examined evolutionary changes related to increased dis-
persal capabilities of such forms. In southern England, several insects have
shown substantial range expansions correlated with climatic warming
(Thomas et al. 2001). One of these, the brown argus butterfly (
Aricia
agestis
), has also shown a host plant shift correlated with host plant avail-
abilities in areas into which it has spread. In newly colonized areas, it has
shifted its preference more strongly to a wild geranium (
Geranium molle
)
that is more widespread in the invaded areas. Preference for this species
by the progeny of butterflies taken from invaded areas and reared in cap-
tivity shows that this shift has a genetic basis.
In Europe, strong evidence also exists for evolutionary responses of
several migratory birds to changing climate. The blackcap (
Sylvia atri-
capilla
), one of the Old World warblers, wintered almost exclusively in the
Mediterranean region prior to the 1950s. Since then, a large wintering
population has developed in England (Berthold 1995).These birds come
from central Europe and have been shown experimentally to possess a
genetically based migratory orientation pattern that enables them to
migrate west-northwest to their wintering area in England. Other land
birds, such as the serin (
Serinus serinus
), have expanded their ranges north-
ward and modified their migration patterns, so populations that were
