Population Dynamics Population Dynamics • Review: What is a population? Group of organisms of the same species that occupy the same geographic place at the same time Populations are described by density, distribution, and growth rate • Population Density: number of organisms area per unit ________ NASA 1994 Spatial Distribution spacing of a • Dispersion: the pattern of _________ population within an area • 3 types – Uniform: Organisms equal distance apart – Clumped: Organisms gathered in a certain area – Random Organisms appear to be spaced out at random Growth Rate- explains how fast a given population grows • Factors affecting the size of a population – Births: – Deaths: New organisms are produced End of an organism’s life – Immigration: – Emigration: into a Movement of individuals ______ population from another population out of a Movement of individuals _____ population and into another population • When a population is declining, what two factors are likely outpacing the other two factors? Emigration and Death Population Growth is based on available resources • When resources are abundant, a population has the opportunity to grow rapidly _________ • This is called exponential __________ growth J-shaped curve resources • Most populations face limited _________ logistic and show _________ growth • Carrying Capacity is the number of individuals that the resources in the _____________ environment can normally support S-shaped curve Reproductive Patterns • Other factors need to be considered such births as number of ________ per reproductive cycle, ______ age reproduction begins, _____ life span of the organism,… • Plant and animals are placed into groups based on their __________ reproductive factors r-strategists K-strategists Life span short Long # of offspring many Few Body size small Large Development short Long Reproduction begins Early in life Late in life Survivorship curves tell ___________ us something about how long individuals survive in a population Type I survivorship curves are for species that have a high survival rate of the young, live out most of their expected life span and die in old age. Humans are a good example of a species with a Type I survivorship curve. Type III survivorship curves are found in species that have many young, most of which die very early in their life. Plants, oysters and sea urchins are examples of species that have Type III survivorship curves Type II survivorship curves are for species that have a relatively constant death rate throughout their life span. Death could be due to hunting or diseases. Examples of species exhibiting a Type II survivorship curve are coral, squirrels, honey bees and many reptiles.