Biology 2485B Lecture Notes - Lecture 18: Overexploitation, Invasive Species, Allele Frequency
6 May 2019
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Document Summary
Population growth rate = births + immigration deaths emigration: balance of these processes determines whether the pop grows, stays the same size, or declines. Major current threats to biodiversity decrease births and increase deaths. Invasive species: habitat alteration (loss, fragmentation, degradation, pollution, overharvesting, climate change. Other reasons why a population might not rebound when its size is pushed too low: random demographic events (e. g. , skew in sex ratio, genetic effects (loss of genetic variation and inbreeding) These can also set up positive feedback loops that reduce population size further. To understand extinction process, need to understand some processes (including feedback loops) that occur once pop sizes start to become small. Stochastic events and processes can"t be definitively predicted only their probability of occurrence can be known. The pop growth rate and the vital rates that determine it represent an average for all individuals in the population.
