EXAMPLES OF SPECIALIZATIONS TO FACILITATE PREDATION OR DEFENSE
Temporally Specialized Spider Web . . . . The Thermoregulatory Defense . . . . Sometimes Social Spiders . . . . Where do Poison Arrow Frogs get their Ammunition?
ALLEE EFFECT. "Perhaps the commonest [expression of the] Allee effect occurs in species that congregate to protect themselves against predators. Animals such as flamingos and penguins just won't get into breeding mood unless they are surrounded by many other mating individuals. In such species, natural selection favours animals that synchronise their breeding because their offspring are more likely to survive the vulnerable early weeks if there are plenty of other young animals around for potential predators to pick off. "This may not be a problem for a species that is usually abundant," says Bill Sutherland from the University of East Anglia, "but can become important once it becomes rare or once people are trying to breed it in captivity." In some species, a behaviour that probably evolved as a way of swamping potential predators, seems to have developed into a near-unbreakable psychological dependence." -- from Adrian Barnett's essay, "Safety in Numbers," in New Scientist 03 February 2001
PREY FIDELITY? "Ecological models suggest that biodiversity arises from the partitioning of resources among species, allowing new species with unique resource-use patterns to invade communities. However, these models have not been tested empirically because real-world species differences in resource use are often confounded with other species traits (size, rate of growth, metabolic rate, etc.). Finke and Snyder (p. 1488) overcome these obstacles by exploiting host-fidelity behavior among a group of parasitoid wasps that attack aphids. While each wasp species is a generalist consumer that attacks many aphid species, individual wasps prefer to attack the same host species from which they themselves emerged. By rearing wasps of different species on each of several aphid species, consumer wasp communities were constructed that could be independently manipulated for consumer species identity, species richness, and patterns of resource use. Exploitation of the aphid resource clearly improved with greater consumer biodiversity, but only when constituent consumers were specialists with distinct resource-niche partitioning. Thus differences in resource use among species, rather than biodiversity per se, intensify resource exploitation at higher levels of consumer biodiversity." SCIENCE, September 12 2008, 321 (5895)