Ch. 53: Community Ecology
Biology, 8th edition, defines community ecology as “the study of how interactions between species affect community structure and organization. ”Biologists recognize that the organisms in communities are continuously evolving in association with one another. This implies that community structure and organization are also continuously evolving. This activity focuses on some of the key principles and factors that can affect the structure and organization of communities.
1. Define the following ecological principles:
top-down vs. Bottom-up controls
trophic structure or trophic levels
2. For the next 2 questions, analyze the situations described. Then explain which of the above ecological principles could be active in each particular situation.
a. A small clan of hyenas killed an antelope. While they were feeding on the carcass, two female lions approached, growled at the hyenas, and chased them away from the carcass.
b. Two species of closely related swallows live in England. The black swallow lives in coniferous forests, and the yellow swallow lives in deciduous forests. In Ireland, where the black swallow has never been introduced, only the yellow swallow is present and it lives in both coniferous and deciduous forests.
____3. Which of the following statements is consistent with the principle of competitive exclusion?
A) Bird species generally do not compete for nesting sites.
B) The density of one competing species will have a positive impact on the population growth of the other competing species.
C) Two species with the same fundamental niche will exclude other competing species.
D) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species.
E) Evolution tends to increase competition between related species.
____4. The sum total of an organism's interaction with the biotic and abiotic resources of its environment is called its
A) habitat. B) logistic growth C) biotic potential D) carrying capacity E) ecological niche.
____5. Resource partitioning would be most likely to occur between
A) sympatric populations of a predator and its prey.
B) sympatric populations of species with similar ecological niches.
C) sympatric populations of a flowering plant and its specialized insect pollinator.
D) allopatric populations of the same animal species.
E) allopatric populations of species with similar ecological niches.