Download Lecture 33

I. Populations (Chap 36.1-7)
A. Size
1. smaller populations risk extinction
2. population growth is limited
a. carrying capacity = the maximum number of individuals
an area can support
b. is a dynamic value
- limiting factors: space, water, light, nutrients
3. growth slows as carrying capacity is reached
4. adaptations
a. r-selection life history
- favors exponential growth
- early reproduction
- high mortality
- offspring
- no parenting
- many weed species and insects
b. K-selection life history
- later maturity and onset of reproduction
- produce few but well-cared-for offspring
- fits larger terrestrial vertebrates
B. Density
1. number of individuals per unit area
2. density-independent effects on population growth
a. affect growth rate
b. effects are independent of population size
- weather, natural disaster
3. density-dependent effects:
- mainly due to increased competition as population grows
3. density-dependent effects:
- mainly due to increased competition as population grows
- behavioral changes, migration
3. density-dependent effects:
- mainly due to increased competition as population grows
- behavioral changes, migration
- spreading of disease through a dense population
C. Dispersion patterns
1. scatter of organisms in the “range” area
2. clumped pattern (most common in nature)
3. uniform pattern (territoriality)
4. random pattern (scatter by currents)
II. Competition (Chap 37.1-3)
A. Niche
1. how an organism uses its available resources
2. an organism’s “biological role”
B. Habitat (the place where an organism lives)
C. Intraspecific competition
- between individuals of the same species
D. Interspecific competition
1. different species competing for the same resources
2. competitive exclusion principle:
- two very similar species competing for the same resources
cannot coexist in the same place
- one will be slightly more efficient and out-reproduce the
other
III. Coevolution and Symbiosis (Chap 37.4-5)
- life relationship between different kinds or organisms
- lichens, mycorrhizae, N2-fixing bacteria
A. Commensalism
1. one species benefits, with benign effect
2. barnacles growing on whales
3. birds and cows
B. Mutualism
1. both species benefit
2. flowering plants and pollinators
B. Mutualism
1. both species benefit
2. flowering plants and pollinators
3. carpenter ants and aphids
C. Parasitism
1. parasite benefits while host can ultimately be harmed
2. lice, internal parasites
3. brood parasitism
IV. Predator-Prey Interactions (Chap 37.5)
A. Chemical defenses
1. plants
- toxins
- bad aromas or tastes
- some animals have adapted
2. animals
- venoms and toxins
- some maintain toxic plant compounds in their tissues
(Monarch caterpillar)
B. Coloration
1. warning (aposematic)
- found on many poisonous animals
- on many insects that eat toxic plants (Monarch)
2. cryptic coloration (camouflage)
C. Mimicry
1. fake warning coloration (Batesian)
- Viceroy and Monarch
Viceroy
Monarch
Batesian mimicry
2. resemblance among unrelated poisonous species (Müllerian)
- common marking pattern or coloration