Slides on Population Growth | Introductory Wildlife | NRM 2301, Study notes of Earth Sciences

Download Slides on Population Growth | Introductory Wildlife | NRM 2301 and more Study notes Earth Sciences in PDF only on Docsity! 9/18/2008 1 Population Ecology A group of organisms usually of the same species, occupying a defined area during a specific time. Why is population the unit of interest? it is from the population that we can judge the effectiveness of our management efforts. it is from population that we gather information and formulate management plans it is population that provides renewable natural resource NOT the individual Characteristics of populations Density - # animals per unit area Birth and Death rates Natality – Birth rate - # of births per x number of individuals per year M t lit D th t # or a y – ea ra e - of deaths per x number of individuals per year Sex & Age structure Sex ratios - # of males versus females Age structures Social structure More characteristics . . . Recruitment – # of new individuals reaching breeding age (includes immi-) Fecundity - # of eggs d d f lpro uce per ema e Fertility - % of eggs that are fertile Production – Actual number of offspring produced by a population 9/18/2008 2 Some definitions for population Biological definition A specific local group of individuals that are actually or potentially interbreed (deme) Statistical definition a somewhat arbitrary grouping of inidividuals of a species that is usually bounded by the criteria of a specific study American Robin Data Mean=2.5; SD=0.925; Knupp et al 1977 Types of factors influencing population growth Density dependent factors Influence related to density of population Density independent factors Influences NOT related to density of population Types of population growth Birth rates Population age structure effects age classes of breeders Mating systems monogamy many bird species polygamy polyandry - some birds polygyny - many ungulates promiscuity serial promiscuity