AP Bio – Ecology Podcast 9

1. AP Bio – Ecology Podcast 9 Life History Strategies and Population Growth

2. Life History Strategy • How an organism goes about its life while achieving the maximum number of surviving offspring possible.

3. Natural Selection Favors a Life History Strategy That Favor Maximum Reproductive Success • Natural selection always acts to maximize the number of offspring that are successful. • Natural selection favors those life history strategies that maximize the number successful offspring

4. More than One Way to Maximize the Number of Successful Offspring • Not all organisms are the same. • Not all environments are the same. • Because there’s variety in organisms AND the environments in which they live, there’s variety in life history strategies. • Though generally speaking certain patterns seem most common

5. r-selected vs. k-selected species R-strategist K- strategist Tend to be found in stable habitats Long life spans Begin breeding later in life Long generation times Few offspring Lots of parental care Infant mortality low • Tend to be found in unstable, rapidly changing habitats • Short life spans • Begin breeding early in life • Short generation times • Large numbers of offspring • Little parental care • Infant mortality high

6. r- selected species

7. k - selected

8. Survivorship Curve • Graphical representation of how many organisms of a species survive at a given age. • Reveals general patterns according to life history strategy. • 3 main curves are typical

9. 1000 Human (type I) Hydra (type II) 100 Survival per thousand Oyster (type III) 10 1 0 25 50 75 100 Percent of maximum life span Survivorship curves What do these graphs tell about survival & strategy of a species? I. High death rate in post-reproductive years II. Constant mortality rate throughout life span III. Very high early mortality but the few survivors then live long (stay reproductive)

10. 1000 Human (type I) Hydra (type II) 100 Survival per thousand Oyster (type III) 10 1 0 25 50 75 100 Percent of maximum life span Life strategies & survivorship curves K-selection r-selection

11. Survivorship curves • Graphic representation of ground squirrel life table The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females. Belding ground squirrel

12. If reproduction is so key, why don’t all organisms just reproduce all the time? • Trade-offs • Parental Survival vs. reproduction of offspring • Reproduction demands lots of energy investment • Energy into making eggs • Energy into nest building, etc. • Energy into providing food for offspring • All of this is energy that the parent cannot put into their own survival needs

13. Parental survival Kestrels (a falcon): The cost of larger broods to both male & female parents

14. Significant advances in medicine through science and technology Industrial Revolution Human population growth adding 82 million/year ~ 200,000 per day! What factors have contributed to this exponential growth pattern? 20127billion 20056.5 billion Population of… China: 1.3 billion India: 1.1 billion U.S. 313 million 1975 4billion K? Bubonic plague "Black Death" 1650500 million

15. USA 30.2 Germany 15.6 Brazil 6.4 Indonesia 3.7 Nigeria 3.2 India 2.6 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Acres Amount of land required to support an individual at standard of living of population Ecological Footprint over-population or over-consumption? uneven distribution: wealthiest 20% of world: 86% consumption of resources 53% of CO2 emissions

16. AP Bio Ecology Podcast 10 Human Impacts on the Environment

17. gypsy moth Introduced/Invasive species • Non-native species • transplanted populations grow exponentially in new area • out-compete native species • loss of natural controls • lack of predators, parasites, competitors • reduce diversity • examples • African honeybee • gypsy moth • zebra mussel • purple loosestrife • Phragmites • Kudzu • Northern snakehead kudzu

18. ~2 months ecological & economic damage Zebra mussel • reduces diversity • loss of food & nesting sites for animals • economic damage

19. 1968 1978 Purple loosestrife • reduces diversity • loss of food & nesting sites for animals

20. Phragmites

21. Northern Snakehead

22. Kudzu

23. Distribution of population growth 11 uneven distribution of population: 90% of births are in developing countries 10 high fertility 9 uneven distribution of resources: wealthiest 20% consumes ~90% of resourcesincreasing gap between rich & poor There are choices as to which future path the world takes… medium fertility 8 7 low fertility 6 World total World population in billions What is K for humans? 10-15 billion? the effect of income & education 5 4 Developing countries 3 2 1 Developed countries 0 1900 1950 2000 2050 Time

24. Ecological Footprint deficit surplus Based on land & water area used to produce allresourceseach country consumes & to absorb allwastesit generates

25. AnyQuestions?

26. Measuring population density • How do we measure how many individuals in a population? • number of individuals in an area • mark & recapture methods Difficult to count a moving target sampling populations

27. Evolutionary adaptations • Coping with environmental variation • regulators • endotherms • homeostasis • (“warm-blooded”) • conformers • ectotherms • (“cold-blooded”)

28. Bright blue marble spinning in space Ecology

29. Studying organisms in their environment biosphere ecosystem community population organism