Unformatted text preview: 9/1/2011 ECOL 1000 Population 7 billion: 2011 Population growth 1: Measuring population size Questions: How do we estimate population size? In what ways do population sizes change? What is ecology? Ecology: how organisms interact with their environments , "house"; -, "study of" What is population ecology? Popn. ecology: how populations interact with their environments How populations change over time and space Applications of Population Ecology
Forecasting human population Pest outbreaks Harvesting scenarios Endangered species 1 9/1/2011 What is a population? Population : A group of individuals
(all same species) that uses common resources in a given location What do populations do? Populations rarely remain stable Population Dynamics = changes in N over time Abundance/size (N): Number of individuals Population size Population explosions Population increase: bald eagles Video 1: NBC: Lionfish explosion Population declines Endangered Species
Video 2: 60 minutes: Mountain gorillas 2 9/1/2011 Population decline: frogs Population Declines Unchecked decline = Extinction Population declines are the basis for inclusion on the Endangered Species List. Assessing Extinction Risk * (N)
www.redlist.org Population fluctuations Canadian Lynx Snowshoe Hare Video 3: NBC: Too Many Snouts Video 4: Animal Planet : Canadian Lynx 3 9/1/2011 Hudson Bay Trading Co., Canada 1850 - 1950
Population size (N)
Snowshoe Hare Canadian Lynx Lynx / Hair Population ( N ) Summary (1): What do populations do? Rabbit Fur Lynx Pelts Population Oscillation Populations often fluctuate. One population can influence another. Time (days, months, years, etc) Populations can grow, shrink, or fluctuate Course materials: www.elc.uga.edu Turning Technologies NXT clicker First use of clickers Tues Aug 23 Register clicker beforehand student.turningtechnologies.com Instructor email: [email protected] Class: ECOL 1000 ECOL 1000H Honors section Meets Friday 1:25-2:15PM Ecology conference room N is simply the number of individuals in a population. Count all individuals (Plants and sedentary species) In the Hudson Bay Co. "experiment," all animals died. How do we calculate ( N ) without killing everything ? 4 9/1/2011 U.S. Population Census 1790-2010 Every 10 yrs
320,000,000 270,000,000 Aerial surveys Population size of U.S. 220,000,000 170,000,000 120,000,000 70,000,000 20,000,000 1780 30,000,000 1830 1880 1930 1980 Year Carolina chickadee Capture Mark Release Recapture BUTTERFLY Estimating Population Size ( N ) Capture - Mark - Release - Recapture
[ # of individuals marked & released initially ] x's [ # of individuals ( both marked & unmarked ) caught later ]
. N= [ # of marked individuals recaptured ] 5 9/1/2011 Capture - Mark - Release - Recapture 2 short-term assumptions Capture - Mark - Release - Recapture 4 longer-term assumptions 1) Catch rate for marked and unmarked specimens is the same. 2) Random mixing of marked and unmarked individuals. 1) 2) 3) 4) No immigration No emigration No births No deaths 713 Day 1 : 345 butterflies marked & released. Day 2 : 155 butterflies caught, of which 75 were marked. N = 345 x 155 = 75
Speyeria mormonia The Mt. Parnassus Butterfly Parnassius spp. 6 9/1/2011 Day 1 : 30 Day 2 : 15 butterflies marked & released. 20 butterflies caught, of which 10 were marked. N = 15 x 20 = 10 Mountain butterfly populations can be quite small! 7 9/1/2011 Mountain tops are islands!
Video 5: ABC "Falling off of Mountain Tops" Summary (2) CMRR: measures population size Assumptions must be met Montane butterfly populations can be quite small Species that inhabit mountains can be well adapted locally, but face a high risk of extinction if conditions change 8 ...
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