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#density-dependent mortality

3 public questions tagged with this topic.

Population Regulation

Which of the following groups reported highest frequency of density-dependent mortality?

The keyed empirical comparison identifies insects as the group in which studies reported the highest frequency of density-dependent mortality. Plausible mechanisms include larval competition for food, cannibalism, pathogen transmission, and crowding within discrete host plants or breeding patches. This is a reported pattern across surveyed studies, not a universal rule that every insect population is more strongly regulated than every vertebrate population. At low density, ordinary competition weakens, but an Allee effect can reverse the expected advantage of rarity. At high density, resource

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5

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Population Regulation

Which population shows density-dependent mortality due to refuge space limitation?

The kelp-perch example links density-dependent mortality to a finite number of refuges. As fish density rises, safe crevices or shelter sites become limiting, leaving more individuals exposed to predators. Mortality therefore increases disproportionately with abundance. The important mechanism is not simply predation, but the interaction between predation risk and competition for protective space. Density dependence is identified by a change in a per-capita demographic rate as abundance changes. Negative density dependence restrains growth and can regulate abundance; positive density dependenc

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5

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Population Ecology

Which curve in survivorship shows density-dependent mortality?

“Type I” for which curve in survivorship shows density-dependent mortality. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“Type II”, “Type III”, “Logistic”—refer to different states, processes, or scales and therefore do not express the same caus

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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