ENV100Y5 Lecture Notes - Lecture 8: Commensalism
69
ENV100Y5 Full Course Notes
Verified Note
69 documents
Document Summary
Type i: more deaths at older ages. Type ii: equal number of deaths at all ages. Type iii: more deaths at young ages: e. g. humans, e. g. seagull, e. g. frogs. Populations may grow, shrink, or remain stable. Steady growth rates cause exponential population growth. Density-dependent factors: the maximum population size of a species that its environment can sustain, limiting factors, limiting factors whose influence is affected by population density, disease, parasites, competition. Density-independent factors: limiting factors unrelated to population density, natural disasters, climate change. As one species declines, other species may appear. Human development now displaces other species and threatens biodiversity. Social and economic factors affect species and communities. Conservation seen as an obstacle to development. Environment is viewed as only a source of resources. In 1988 european ships discharged water into lake st. clair, canada. Within 2 years, zebra mussels in all 5 great lakes. Hundreds of millions of dollars of damage to property.
