Transcript Slide 1
What is competitive exclusion? Give an example. Students will address how populations are distributed. Students will describe how populations are sustained over time. Geographic range- the area inhabited by a population Factors that determine population range: ◦ Abiotic- non-living factors in an organism's environment Ie. Climatic factors, edaphic factors, & social factors ◦ Biotic- living factors in an organism's environment Ie. Predators, competitors, parasites A species may not be able to expand its pop. range b/c it can’t survive the conditions in another region Population Density- measurement of the number of individuals living in a defined space ◦ Example: 200 deer in 10 square Km; there would be 20 deer per square Km ◦ Example: 40 people in 20 square units; there would be 2 people per square unit Population Distribution: A way in which populations are spread in an area ◦ Uniform dispersion: Live specific distances from one another ◦ Random dispersion: spread randomly within an area ◦ Clumped: Individuals live close together in groups Facilitate mating, gain protection, food resources Occurs when there is fierce competition for resources or territory Occurs when individuals set up territories for feeding, breeding, and nesting Few pop. live this way in nature Occurs in areas of the habitat with favorable conditions for survival 1. 2. 3. Each species is adapted to a limited set of ecological conditions- patchy in a habitat Many species gather in social groups for survival and reproduction Adult species don’t disperse young over a large distance Occurs when habitat conditions are nearly uniform (steady resources & organisms don’t attract or avoid one another) Create a list that explains how a population may change in size. Explain the causes that lead to these effects. Cause Effect Students will address how populations are distributed. Students will describe how populations are sustained over time. Increase in Population: ◦ Immigration: movement of individuals INTO a population ◦ Births: Increase the number of individuals in population Decrease in Population: ◦ Emigration: movement of individuals OUT of a population ◦ Deaths: Decreases population Population Growth Rate= (birth rate- death rate) (# of individuals) The maximum rate of increase per organism under ideal conditions ◦ Rate depends on the age each generation starts to reproduce, how often an individual reproduces, & how many offspring are produced Human population biotic potential= 6% each year Rats biotic potential= 1.5% each day Bacteria biotic potential= 250% an hour Directly determined by the amount of resources available ◦ Exponential Growth ◦ Logistic Growth Rapid growth that occurs when a population grows under ideal conditions with “unlimited” resources ◦ Lag phase= slow growth period J-shaped curve Increased birth and immigration Lag phase + Carrying capacity- maximum # of individuals of a pop. an environment can sustain for a long period of time ◦ in pop. resources therefore less individuals are born & more may die from deficiency Growth that may follow a period of exponential growth when a population’s growth slows/levels off. ◦ Meets carrying capacity S- shaped curve Occurs when emigration & death exceed immigration & birth Carrying Capacity Population Time Is the combined effects of all the factors that limit pop. growth ◦ This resistance is the force opposing biotic potential Limiting factor: this factor has the greatest effect in keeping down the size of the population ◦ Density-dependent: factors that are affected by the number of individuals in an area (competition, predation, parasitism and disease) ◦ Density-independent: environmental aspects that are not affected by how many individuals there are (typically abiotic like weather, natural disasters, human activity) Populations Can be described by Dispersion Three Types: 1. 2. 3. Density Growth Rate Affected by Limiting Factors Which can be: 1. 2. Which can be which are usually which are usually