Exponen'al growth Limi'ng factors Environmental resistance Carrying capacity logis'c growth curve

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1 Exponen'al growth Popula)on increases by a fixed percent Fixed percent of a large number produces a large increase Graphed as a J- shaped curve Cannot be sustained indefinitely It occurs in nature With a small popula)on and ideal condi)ons Humans in ideal condi)ons? Exponen)al growth rarely lasts for long Limi'ng factors Physical, chemical, and biological characteris)cs restrain growth Water, space, food, predators, and disease Environmental resistance All limi)ng factors taken together that stop exponen)al growth Stabilizes the popula)on size Carrying capacity Maximum species popula)on environment can sustain An S- shaped logis'c growth curve Limi)ng factors slow and stop exponen)al growth Carrying capaci)es change Humans have raised their carrying capacity by decreasing the carrying capacities for other. 1

2 Popula)on s density Can increase or decrease the impact of certain factors Density- dependent factors Limi)ng factors whose influence is affected by popula)on density Increased density Increased risk of preda)on Increased compe))on for mates Logis)c growth curve Represents the effects of density dependence Density- independent factors Limi)ng factors not affected by popula)on density Floods, fires, and landslides 2

3 Popula)on regula)on Not only due to environmental limi)ng factors Also asributes of the organism itself Bio'c poten'al An organism s ability to produce offspring K- selected species Animals with long gesta)on periods and few offspring quality, not quan)ty Have a low bio)c poten)al Must compete for resources Stabilize at or near carrying capacity r- selected species: animals which reproduce quickly quan)ty, not quality Have a high bio)c poten)al 3

4 As environmental condi)ons change Many species are affected Mul)ple species can go ex)nct Costa Rican cloud forest drying many amphibian, rep)le, and bird species also disappeared Species from lower, drier habitats appeared Composi)on of en)re communi)es changed Factors speeding rate and degree of change in popula)ons / communi)es Human development Urban sprawl Resource extrac)on Mountaintop removal Popula)on growth See above Safeguarding biodiversity Establishing na)onal parks Iden)fying and protec)ng endangered species Recovering species popula)ons Management programs Earth s biodiversity determined by Natural selec)on Specia)on Ex)nc)on Understanding how ecological processes work at the popula)on level Cri)cal to protec)ng biodiversity Popula)on ecology also informs the study of human popula)ons Key to environmental science 4

5 Which of the following is NOT a part of the process of natural selec)on? a) Organisms struggle to survive b) Organisms produce more young than can survive c) Individuals of a species tend to have very similar gene)c characteris)cs d) Some individuals are beser suited to their environment than others e) Surviving individuals pass their genes on to their offspring Which of the following is NOT true about gene)c muta)ons? a) They are accidental changes in DNA b) They are always lethal c) They can be passed on to future genera)ons d) They can lead to gene)c varia)on e) Muta)ons, along with sexual reproduc)on, lead to varia)on in individuals Biological diversity includes all of the following EXCEPT: a) Species diversity b) Genetic diversity c) Population diversity d) Community diversity e) All of these are included in the concept of biodiversity. 5

6 Allopatric specia)on would NOT occur in : a) Half of a popula)on that mates in May, and the other half that mates in June b) A popula)on separated by the Mississippi River c) A popula)on separated by a glacier d) A popula)on separated by the Rocky Mountains e) It would occur in all of these popula)ons. The disappearance of a species from Earth is called: a) Endemism b) Specia)on c) Ex)nc)on d) Phylogene)cs e) Randomiza)on An ecosystem is defined as: a) All living things on Earth b) Members of the same population that can interbreed c) Interacting species in an area d) Communities and the non-living material they interact with e) Members of the same species that live in the same area 6

7 is defined as the number of individuals of a population per unit area. a) Population size b) Population density c) Population distribution d) Sex ratio e) Age structure is defined as the proportion of males to females. a) Population size b) Population density c) Population distribution d) Sex ratio e) Age structure Which of the following is a limiting factor? a) Water b) Space c) Food d) Predators e) All of these are limiting factors. 7

8 A K selected species generally has all of the following characteristics EXCEPT: a) Large size b) Short-lived c) Good competitor d) Constant population size e) Slow population growth Should we care whether a species goes ex)nct? a) Yes, because all life is important and valuable. b) Yes, because we are causing this wave of ex)nc)on, so we should fix it. c) We should not, because it s a natural process. d) I don t care; it really does not affect me. Do you think humans are subject to limiting factors and, ultimately, a fixed carrying capacity? a) Yes, although we have raised the carrying capacity, there are limits to the number of humans the Earth can support. b) Yes, but technology will keep raising the carrying capacity, so it s not much of a problem. c) No, humans are no longer constrained by environmental limits, due to our technology and ability to manipulate the environment. d) I don t care. It really does not affect me. 8

9 Which of the following graphs shows a popula)on that will have lots more individuals in the future? (a) (b) (c) (d) Which type of distribu)on shows individuals arranged according to the availability of resources? a) Random b) Uniform c) Clumped d) None of these What does this graph show? a) The effects of carrying capacity on popula)on growth b) A popula)on that keeps growing un)l all individuals die c) The effects of exponen)al growth d) The effects of increasing carrying capacity e) None of these 9