Insect Ecology - An Ecosystem Approach 2nd ed - Chapter 15 pptx

... drought- intolerant vegetation and litter accumulation. The relatively isolated higher elevation and riparian zones were more mesic and supported shade-tolerant (but fire- and drought-intolerant) fir and spruce forests. ... 442 characterized by relatively arid conditions and frequent droughts that historically maintained a sparse woodland dominated by drought- and fire-tolerant (but shade-intole...

Ngày tải lên: 06/07/2014, 14:20

... exposure to altered temperature and moisture (Seastedt and Cross- ley 1981a).Anthropogenic disturbances leave straighter and more distinct bound- aries between disturbed and undisturbed patches (because ... growing population, and preda- tors and pathogens respond to increased prey or host density and stress. Popu- lation growth slows and abundance reaches a peak. Competition, predation, and...

Ngày tải lên: 06/07/2014, 14:20

... hierarchical approach offers a means of integrating evolutionary and ecosystem approaches to studying insect ecology. The evolutionary approach IV. ECOSYSTEM APPROACH TO INSECT ECOLOGY 11 001-P088772.qxd ... However, an ecosystem approach provides a framework for integrating insect ecology with the changing patterns of ecosystem structure and function and for appl...

Ngày tải lên: 06/07/2014, 14:20

... environmental changes, as described earlier, any change will alter insect abundance and distribution and may increase the incidence of crop pests and vectors of human and animal dis- eases (Stapp ... forest canopy and are carried by wind currents to new areas (Wellington 1980). The distance traveled by wind- or water-dispersed insects depends on several factors, including flow rate and inse...

Ngày tải lên: 06/07/2014, 14:20

... limited number of resistance mechanisms that confer cross-resistance to plant defenses and structurally related toxicants and, in some cases, to chemi- cally unrelated compounds (Soderlund and ... parasites and pathogens in the hemo- coel (Tanada and Kaya 1993). Behavioral mechanisms also may be used for pro- tection against pathogens. Insects produce a variety of antibiotic and anticancer .....

Ngày tải lên: 06/07/2014, 14:20

... rest and can be exposed sud- denly to startle would-be predators. The margin of the front wings in some sat- urniids are shaped and colored to resemble the heads of snakes (Fig. 4.11) (Grant 004-P088772.qxd ... allocated as is K), and 85 Sr (assimilated and allocated as is Ca), became use- ful tools for tracking the assimilation and allocation of nutrients through organ- isms, food webs, and...

Ngày tải lên: 06/07/2014, 14:20

... Following the appearance of transgenic insect- resistant crop species in the late 1980s, geneti- cally engineered, Bt toxin-producing corn, cotton, soybeans, and potatoes have replaced nontransgenic varieties ... labora- tory experiment with sex-linked mutant genes in Drosophila melanogaster (Peterson and Merrell 1983), mutant and wild-male phenotypes exhibited about the same viability, but...

Ngày tải lên: 06/07/2014, 14:20

... (Fig.7.9).Mound den- sities were significantly highest along dirt roads not covered by forest canopy and lowest along roads covered by forest canopy. Powerline and graveled or paved roads not covered by forest ... increasing corridor width (a) and disturbance frequency (b) at the Savanna River Site in South Carolina. cl-can = closed canopy, pline = powerline cut, and open, gravel, and paved =...

Ngày tải lên: 06/07/2014, 14:20

... 1994, see Chapter 13). Insects are an important food source for a variety of other organisms. Car- nivorous plants generally are associated with nitrogen-poor habitats and depend on insects for ... 1989, Krafft and Handel 1991). A variety of mechanisms for entrapment of insects has evolved among carnivorous plants, including water-filled pitchers (pitcher plants), triggered changes in turg...

Ngày tải lên: 06/07/2014, 14:20

... particular tolerances to disturbance or postdistur- bance conditions (see Chapter 2). Often, legacies from the predisturbance com- munity (such as buried rhizomes, seed banks, woody litter, and animals ... converged toward significantly greater similarity in structure following fire in a grassland ecosystem than pre- dicted by a random model. Fukami et al. (2001) modeled compartmentalized c...

Ngày tải lên: 06/07/2014, 14:20