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FW 491 – Online Ecological Module By: Jessica Caton Introduction to Population Ecology • What is a population? – A group of individuals of a single species inhabiting a specific area (Molles 2010, p. 202) • Areas of study involved – Population genetics – Population dynamics Population Dynamics An area of population ecology concerned with the factors influencing the expansion, decline, or maintenance of populations (Molles 2010, p. 222) • Increases = Birth and Immigration • Decreases = Death and Emigration Population Dynamics (con’t) Important for ecology to understand/prevent decline and extinction of endangered species Antarctic Species of Interest: Adélie Penguin (Pygoscelis adeliae) • Physical appearance: – – – – Medium-sized (2 feet tall), black and white Angular head and tiny bill White eyering Longest feather on body is the tail • Smallest penguin in Antarctica • One of the pack ice Antarctic penguins • Most numerous bird in Antarctica Adélie Penguins and Climate Change • One of the best studied birds • Changing population of species: numbers dropped a third • Sea-ice decline, Adélie penguin populations decline • Evolution of environmental instability? Life Tables • A table that uses age specific information to estimate important population dynamic traits on a population • Types of life tables: – a table based on individuals born (or beginning life in some other way) at same time (Molles 2010, p. 230) – Static life table: a life table constructed by recording the age at death of a large number of individuals; a snapshot of survival within a population during a short interval of time (Molles 2010, p. 231) Life Table Summary Time Cohort (horizontal) Composite Time-specific (static, vertical) Data Collection for Life Table Variables in Life Tables • • • • • nx lx mx lxmx R0 • R0 = ∑lxmx Survival and Mortality in a Population of Adélie Penguins (Ainley & DeMaster 1980) Survivorship Curve • A graphical summary of patterns of survival in a population (Molles 2010, p. 231) • Three types: – Type 1 = High mortality in older individuals – Type 2 =Constant mortality rate – Type 3 =High mortality in juveniles