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Ecology! The easy stuff .

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Presentation on theme: "Ecology! The easy stuff ."— Presentation transcript:

1 Ecology! The easy stuff 

2 Populations Population: all individuals of 1 species in area
Population size : number of individuals Population density : number per area Population distribution : dispersal pattern

3 Distribution patterns
1) Clumped: most common, a) group around resources b) social behavior c) lack of offspring dispersal 2) Uniform (or close enough) a) territory division 3) Random – rare a) uniform resources b) ignore each other

4 Population Size Estimates
1) full count 2) Quadrats 3) Transects 4) Mark-recapture m-r good for organisms that move around a lot

5 Mark-recapture Based on assumption: % marked on day 2 same as
the % of the total population that is marked Steps: day 1 capture organisms & mark them day 2 capture organisms & see what % are marked calculation day 2 marked = day 1 marked day 2 total total population

6 Population Growth Positive growth …….. birth & immigration
Negative growth …… death & emigration Migration : periodic change w/ seasons Zero population growth (ZPG) : deaths = births Per capita = per individual Net reproduction = births - deaths

7 Rapid Population Growth
Exponential growth : population grows at a rate proportional to its size a) ideal conditions allow max growth rate Biotic potential : max growth rate for a population Doubling time: time for pop to double size

8 Logistic Population Growth
Exponential Growth slowed by 1) Density dependent limiting factors predation, parasites, disease limited resources, competition 2) Density independent limiting factors weather, natural disasters, humans

9 Carrying capacity = Max # individuals an area can support indefinitely (D) Steady state #2 on graph Life history patterns: adaptations that influence survival, reproduction & population size

10 Life History Patterns r-selected
a) favor low pop density (d independent) b) quick production of many small babies c) high biotic potential so called r-selected K-selected a) favor high pop density (d dependent) b) good competitors c) low biotic potential & parental care

11 Life History Strategies

12 Different Life Histories =
Different Survivorship Curves Type I : live long & prosper (parental care) k-selected Type II : could die at any time… good luck Type III : high infant mortality r-selected

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14 Human Population growth
Homo habilus – 1 billion……2.5 my growth to 2 billion…………..123 years Growth to 3 billion …………. 33 years Growth to 4, 5, 6 ………….. 14, 13, 12

15 Fertility Rates and $$$$$$$
Total Fertility Rate (TFR) – average # children born per woman World wide TFR = 6.5 Replacement = 2.1 TFR in developed countries = at or below 2.1 TFR in developing countries = highest

16 Demographic Transition Model

17 Age Structure Diagrams
3 categories of individuals: -pre-reproductive (base of diagram) -reproductive (center of diagram) -post-reproductive (top of diagram) Fast growth = wide pyramid shape Slow growth = narrow pyramid shape ZPG = straight at bottom, narrow pyramid at top Negative growth = bottom & top more narrow than center

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