Transcript Slide 1
Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. Population Dynamics 1. 2. 3. 4. Populations change in response to environmental stress or changes in environmental conditions. in size (number of individuals) density (# of individual / specific space) age distribution (proportions / age group) dispersion CLUMPED (elephants) UNIFORM (creosote bush) RANDOM (dandelions) Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. Knowing population size is important in making environmental decisions that would affect the population. Making a decision on an estimate that is too high results in EXTINCTION. Making a decision on an estimate that is too low results in unnecessarily hurt people that depend on the animals for food & income. Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. In order to get accurate populations: 1. The population of organisms must be closed, with no immigration or emigration. 2. The time between samples must be very small compared to the life span of the organism being sampled. 3. The marked organisms must mix completely with the rest of the population during the time between the two samples. 4. Organisms are not hurt or disadvantaged by being caught and marked and therefore all organisms have an equal opportunity of being recaptured Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. Quadrat method can be used to determine: POPULATION DENSITY (number of individuals of each species per area) PERCENTAGE FREQUENCY (percent of each species found within an area) PERCENTAGE COVER (percent plant covering a given area) Using Quadrats 1. Mark out area to be sampled (Stage Quadrat). 2. Place Sampling Quadrats ( 1 m2, 10 m2) randomly within the area. 3. Count how many individuals are inside the sample quadrats. 4. Calculate the mean number of individuals per quadrat. Population Size = mean X total area area of each sample quadrat mean = total number of individuals/number of sampling quadrats Quadrat sampling is suitable for plants that do not move around and are easy to find. Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. Lincoln index Capture-Mark-Release-Recapture 1. 2. Capture as many individuals as possible in the area occupied by the animal population, using netting, trapping or careful searching. Mark each individual, without making them more visible to predators and without harming them. Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. 3. Release all the marked individuals and allow them to settle back into their habitat. 4. Recapture as many individuals as possible and count how many are marked and how many are unmarked. 5. Calculate the estimated population size by using the Lincoln Index: Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. 5. Calculate the estimated population size by using the Lincoln Index: population size = N1 X N2 N3 N1 = number caught and marked initially N2 = total number caught in 2nd sample N3 = number of marked individuals recaptured Most suitable for animals that move around and are difficult to find. A scientist traps 14 wood vole, marks them and releases them. The scientist waits 24 hours and then traps 26 wood vole (12 marked and 14 unmarked) in the same area using the same method as the first time. Estimate the wood vole population in this ecosystem. Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. Simpson’s Diversity Index Simpson's Diversity Index is a measure of diversity. In ecology, it is often used to quantify the biodiversity of a habitat. It takes into account the number of species present (richness), as well as the abundance of each species (eveness). Topic 2 Population Dynamics Students will be able to: -describe the importance of calculating accurate population size -calculate accurate population size using the quadrate method and the Lincoln Index -define the term diversity and apply Simpson’s diversity index and outline its significance. example Species Number (n) n(n-1) Woodrush 2 2 Holly (seedlings) 8 56 Bramble 1 0 Yorkshire Fog 1 0 Sedge 3 6 Total (N) 15 64 If you have 8 woodrush 12 holly seedlings 16 bramble 4 yorkshire fog and 17 sedge in a community, what is its diversity using simpsons diversity index.