18.104.22.168.4. Changes in community composition, biotic interactions, and behavior
Differential responses by species could cause existing animal communities to
undergo restructuring. This occurred in prehistoric plant communities because
no analogous communities exist today (Davis, 1990). Similarly, Graham and Grimm
(1990) found no present-day mammal communities that are analogous to some prehistoric
Invertebrates: Potato aphids grown on plants kept in elevated CO2
(700 ppm) showed a reduced response to alarm pheromones in comparison to those
grown on plants in ambient CO2 (350 ppm). Aphids were more likely
to remain on leaves, possibly making them more susceptible to predators (Awmack
et al., 1997b).
Amphibians: Temperature and dissolved oxygen concentrations can alter the behavior
of amphibian larvae, and changes in thermal environments can alter the outcome
of predator-prey interactions (Manjarrez, 1996; Moore and Townsend, 1998).
Birds: In the UK, climate change may be causing a mismatch in the timing of
breeding of Great Tits (Parus major) with other species in their communities
(Visser et al., 1998). The phenology of plants and some animals in the study
area has advanced over the past 23 years, whereas breeding timing of Great Tits
has not changed. This decoupling could lead to birds hatching when food supplies
may be in low abundance (Visser et al., 1998).
Mammals: Post et al. (1999) document a positive correlation between gray wolf
(Canis lupus) winter pack size and snow depth on Isle Royale (USA). Greater
pack size leads to three times more moose kills than in years with less snow.
Fewer moose mean less browsing and thus better growth of understory balsam fir