BIOL 2600 Lecture 2: Section B. Species Richness Patterns
14 Jan 2018
School
Department
Course
Professor
Document Summary
Types of species richness patterns: species-time hypothesis. Caused by faster evolution in tropics, slow migration, and few species adapted to northern climates: species-area hypothesis. Larger areas can support larger populations and a greater range of habitats. Island biogeography theory: says that the number of species on an island reflects a balance between the rate of new species colonizing and the rate at which populations become extinct. Rescue effect: occurs where a small population of species emigrate and rescue the species from extinction. Larger populations less likely to suffer from demographic stochasticity: random variability of population growth rates. Competitive release: the explosion of the range of a species when a competitor is removed. Echo effect: changes in population at two habitat boundaries. These concepts are most relevant to habitat loss as they contribute to the elimination of species. A decrease in habitat size leads to smaller, more isolated populations: species-energy hypothesis.
