1. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Lecture Outlines Chapter 3 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

2. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings This lecture will help you understand: Population characteristics Population ecology Conservation biology

3. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ecology is studied at several levels Ecology and evolution are tightly intertwined Biosphere = the total living things on Earth and the areas they inhabit Ecosystem = communities and the nonliving material and forces they interact with Community = interacting species that live in the same area

4. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Levels of ecological organization Population ecology = investigates the quantitative dynamics of how individuals within a species interact Community ecology = focuses on interactions among species Ecosystem ecology = studies living and nonliving components of systems to reveal patterns -Nutrient and energy flows

5. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Organismal ecology: habitat Habitat = the environment in which an organism lives -Includes living and nonliving elements -Scale-dependent: from square meters to miles Habitat use = each organism thrives in certain habitats, but not in others Habitat selection = the process by which organisms actively select habitats in which to live -Availability and quality of habitat are crucial to an organism’s well-being -Human developments conflict with this process

6. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Organismal ecology: niche Niche = an organism’s use of resources and its functional role in a community -Habitat use, food selection, role in energy and nutrient flow -Interactions with other individuals Specialists = species with narrow niches and very specific requirements -Extremely good at what they do, but vulnerable to change Generalists = species with broad niches that can use a wide array of habitats and resources -Able to live in many different places

7. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics All populations show characteristics that help scientists predict their future dynamics Population size = the number of individual organisms present at a given time -Numbers can increase, decrease, cycle or remain the same

8. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics Population density = the number of individuals within a population per unit area -High densities make it easier to find mates, but increase competition, and vulnerability to predation -Low densities make it harder to find mates, but individuals enjoy plentiful resources and space

9. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics Population distribution (dispersion) = spatial arrangement of organisms within an area -Random – haphazardly located individuals, with no pattern -Uniform – individuals are evenly spaced due to territoriality -Clumped – arranged according to availability of resources -Most common in nature

10. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sex ratio = proportion of males to females -In monogamous species, a 50/50 sex ratio maximizes population growth Age Structure = the relative numbers of organisms of each age within a population -Age structure diagrams (pyramids) = show the age structure of populations Population characteristics

11. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Birth and death rates Crude birth/death rates = rates per 1000 individuals Survivorship curves = the likelihood of death varies with age -Type I: More deaths at older ages -Type II: Equal number of deaths at all ages -Type III: More deaths at young ages

12. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Four factors of population changepopulation Natality = births within the population Mortality = deaths within the population Immigration = arrival of individuals from outside the population Emigration = departure of individuals from the population Growth rate formula = -(Crude birth rate + immigration rate) - (Crude death rate + emigration rate) = Growth rate

13. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Exponential population growth Steady growth rates cause exponential population growth -Something increases by a fixed percent -Graphed as a J-shaped curve Exponential growth cannot be sustained indefinitely -It occurs in nature with a small population and ideal conditions

14. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings 14 Typical Population Growth Curve

15. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Limiting factors restrain growth Limiting factors = physical, chemical and biological characteristics that restrain population growth -Water, space, food, predators, and disease Environmental resistance = All limiting factors taken together

16. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Carrying capacity Carrying capacity = the maximum population size of a species that its environment can sustain -An S-shaped logistic growth curve -Limiting factors slow and stop exponential growth Carrying capacity changes Humans have raised their carrying capacity by decreasing the carrying capacity for other species

17. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population density affects limiting factors Density-dependent factors = limiting factors whose influence is affected by population density - Increased risk of predation and competition for mates occurs with increased density Density-independent factors = limiting factors whose influence is not affected by population density -Events such as floods, fires, and landslides

18. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Biotic potential and reproductive strategies vary Biotic potential = the ability of an organism to produce offspring K-selected species = animals with long gestation periods and few offspring -Have a low biotic potential -Stabilize at or near carrying capacity -Good competitors r-selected species = animals which reproduce quickly -Have a high biotic potential -Little parental care

19. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings K-selected vs. r-selected species

20. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population changes affect communities As population in one species declines, other species may appear Human development now displaces other species and threatens biodiversity -As Monteverde dried out, species from lower, drier habitats appeared -But, species from the cloud-forest habitats disappeared

21. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Challenges to protecting biodiversity Social and economic factors affect species and communities -Nature is viewed as an obstacle to development -Nature is viewed as only a source of resources -Human population growth pressures biodiversity

22. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Costa Rica and its environment Past economic and social forces still threaten Costa Rica’s species and ecological communities -Lush forests are seen as obstacles to agriculture and for timber -The country’s population grew to 3.34 million -Pasture land increased from 12% to 33% -Forests decreased from 80% to 25% -Species were declining and becoming endangered

23. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Costa Rica’s species were in danger Few people saw the need to conserve biological resources -Until it became clear they were being rapidly lost

24. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Costa Rica is protecting its environment The privately managed 10,500 ha (26,000 acre) Monteverde Cloud Forest Reserve was founded in 1972 -To protect the forest, its plants and animals Costa Rica created the country’s first national parks and protected areas in 1970 -Centered on areas of spectacular scenery -Protecting valuable tropical dry forests, turtle nesting beaches, coral reef systems Government support remains strong -Over 25% of its land is under some type of protection

25. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Costa Rico’s protection is paying off Ecotourism: tourists visit protected areas -Providing thousands of jobs and billions of dollars to local economies But parks are still under-protected and underfunded -Restoration is a step beyond preservation

26. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The carrying capacity is: A.average # of offspring carried to term by a species B.greatest # of different niches possible in a given area C.potential growth in the number of species in an area D.maximum population size that a given environment can sustain

27. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings True or False? Ants are K-strategists

28. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Unregulated populations tend to increase by? A.emigration B.linear growth C.exponential growth D.pyramidal growth E.immigration

29. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Which of the following graphs shows a population that will have fewer individuals in the future? (a)(c)(b)(d)

30. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Which type of distribution is a result of individuals guarding their territory? a) Random b) Uniform c) Clumped d) None of these

31. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data What does this graph show? a)The effects of carrying capacity on population growth b)A population that keeps growing c)The effects of exponential growth d)The effects of increasing carrying capacity