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Terms in this set (29)

PLEASE NOTE: For the midterm, I also assume that you have learned something in LAB and other outside activities.

1. Evolution and Natural Selection
a. The theory of Evolution by Natural Selection
1.know the 5 postulates
2.key conceptual point - this theory explains how species can change, and yet also remain "perfect" or well suited to environment
ii. Natural Selection - some more details:
1. Where does variation come from?
a. Sex
b. Mutation
2. What is heritability?
a. Know the definition
b. Key point - Natural selection acts on heritable (genetic) variation, but most traits are both genetically controlled and environmentally influenced

2. Natural Selection in action
a. General Problem - How far can the population mean shift?
i. At first - only as far as variation in population will allow
ii. But variation exists due in large part to mutation
iii. And mutation keeps happening, allowing for more variation

3. Behavioral Ecology - The Evolution of traits which may appear contrary to the selfish pursuit of survival and reproduction
i. Altruistic behavior
1. Why is it surprising? Because we are all selfish bastards
2. How do we explain it?
a. Kin Selection
b. Reciprocal Altruism/Prisoner's dilemma
ii. Extreme Displays and Phenotypes and Sexual Selection
1. Why are they surprising?
2. Honest Signaling - if a signal is costly to produce, only the best males can afford to produce a big signal.

4. Reconciling Darwin and Mendel
a. What is the genetic explanation for continuous variation in traits (like human height)?
i. Incomplete dominance
ii. Polygenic traits
b. Other forces in evolution, or Ways in which allele frequencies can change, or why populations are not at Hardy-Weinberg equilibrium. Know them. Understand the extent to which they can cause allele frequencies to change.
i. Natural selection
ii. Non-random mating
iii. Mutation
iv. Migration
v. Drift

5. Natural Selection, Other forces in Evolution, & Speciation
a. Modes of natural selection
i. Directional
ii. Stabilizing
iii. Disruptive
b. Speciation - the process by which populations diverge, and avoid being homogenized.
i. What is a species?
1. Biological species concept - know definition, and understand when it is or is not a useful definition
ii. Modes of Speciation
1. Allopatric
a. Vicariance
b. Dispersal
2. Sympatric
a. Host-plant specialization
b. Polyploidy
c. Sexual selection? - mate choice
iii. Secondary Contact-what happens when allopatric populations come back together?
1. reproductive isolating mechanisms
a. pre-zygotic
b. post-zygotic
2. Hybrid zone possibilities
a. Thin/stable
b. One way
c. 2 way

6. Phylogenetics - reconstructing evolution
a. Be able to draw and interpret a simple phylogeny
1. Closer evolutionary relationship = more recent common ancestor
b. Key point - a phylogeny is a hypothesis
i. Predictions of chronology
ii. Predictions of transitional forms or vestigial organs and genes
iii. Predictions of biogeography
iv. Phylogenies built from independent data sets should arrive at same answer - especially molecular data

7. Niches and life History
a. The Niche - definitions and examples
i. Competition and competitive exclusion
1. Only one species can occupy a given niche
ii. Competition and niche separation
1. If two species are in competition for the same niche, then what can happen?
iii. The interplay of speciation, secondary contact, character displacement - how do species coexist?
1. Whenever you see 2 or more closely related species coexisting in the same location, there is likely a history of 1) speciation, 2) secondary contact & 3) character displacement that made that possible.
2. Above the level of the species - the diversity of all life is the result of repeated episodes of 1) speciation, 2) secondary contact & 3) character displacement
b. Life History Strategies, Trade-offs
i. Another way of thinking about niches is to see them as a strategy: a way of resource use that makes every species different
ii. Species coexist because they are playing different trade-offs
1. Trade-offs may be based on different kinds of constraints
a. Physical
b. Energetic
c. Tine-Time?
iii. Life history trade offs
1. Life History traits are traits that effect lifetime reproductive success, by influencing:
a. Growth
b. Survival
c. Age at first reproduction
d. Quantity and quality of offspring
e. Parental care
2. These traits are involved in trade-offs such that:
a. The more energy you put into growth, the less you can use for reproduction
b. The more energy you put into reproduction, the less you can use for your own survival
c. The more energy you put into having a large number of offspring, the less you can invest in high quality offspring
3. These trade-offs can be represented in survivorship curves
a. Three types of curves - know the characteristics
i. Type I
ii. Type II
iii. Type III
b. But keep in mind:
i. There are not really 3 distinct types - you can find intermediates
ii. Even for a single species, different populations can have different looking curves - only modern humans with good health care look like a perfect Type I
iii. These curves are all relative - if you focus in on a particular set of organisms, like for example trees, you might find that some trees are more like Type I, others more like Type II, others more like Type III, but no tree is as much of a Type I as humans. It's easier to make a relevant comparison between more similar organisms.

8. Population Growth
a. Basic Models of population growth:
i. Exponential model - know the equation, definition of variables
1. When does exp model apply?
a. Introduced species
b. Rebound after crash
2. When does exp model fail?
a. When resources run out - see logistic model
ii. Logistic model - know the equation, definition of variables
1. When does logistic model apply?
a. Any time there is a carrying capacity - limiting resources
2. When does it fail?
a. When birth rates and death rates don't respond immediately to limiting resources
iii. Limits on population growth
1. Density Dependent factors- effect of factor is worse in dense populations
a. Limited resources of all sorts
b. Disease
2. Density Independent factors
a. Natural disasters of all sorts

i. Competition
1. The force for niche separation - a key factor in the evolution of biodiversity
ii. Commensalisms
1. A big dumb animal becomes habitat
iii. Predation: Big questions
1. Effect of predators on ecosystems
a. Keystone species
2. Do predators control prey populations: In other words, are predators part of the carrying capacity, limiting the total number of prey, or do predators simply eat the "doomed surplus" - the animals they eat will be replaced by others who would've died because of lack of resources
3. The role of predators in evolution
a. Spines, armor, chemical defenses
b. Mimicry - Aposematic coloration
i. Batesian
ii. Mullerian
iii. Is all mimicry a long history of Batesian and Mullerian mimics of some long ago black and orange distasteful species?
iv. Mutualisms
1. fruit and seed dispersers
2. leaf cutter ants and fungi
3. pollinators, ruminants, lichens, eukaryotes, etc.
v. How do all these types of interactions combine to increase biodiversity in a given ecosystem?

a. The role of the sun
i. Energy at the base of all ecosystems - as we've already discussed
ii. Influence on world climate
1. difference between temperate and tropical regions - angle of incidence with the sun
2. seasonality - tilt of the earth
3. Hadley cells - explain patterns of rainfall on a global scale
a. Rainforests
b. Deserts
4. Rain shadows - explain patterns of rainfall on a more local, or regional scale

a. Zones of flora and fauna (plants and animals) defined chiefly by patterns of temperature and moisture
b. 9 basic types (you don't need to know 8 defining characteristics of each type, just understand in general how they are divided up)
c. KEY THINGS to recognize
i. Geographically separated areas of the globe can have extremely similar temperature and moisture levels, leading to...
1. Extremely similar biomes
2. Extremely similar flora and fauna
a. Sometimes this is because it is very closely related species in same niche in different biomes (particularly true of boreal forests)
b. Sometimes this is because of extraordinary levels of convergent evolution (example of moles in different grassland habitats)

a. Primary production
b. Trophic efficiency
i. Food chains
1. producers
2. consumers
ii. Food webs
1. multiple species per level
2. multiple levels per species
iii. Productivity pyramids
c. Large scale significance: Why does the tropical-temperate diversity gradient exist?
i. Larger input -greater resources in tropics
ii. BUT! Speciation must be occurring - the tropics are either
1. A cradle of speciation: more species are "born" in the tropics
2. A museum of speciation: more species persist here because of greater resource availability, thus greater possibility for niche separation

a. The effect of history on biological communities
i. The role of geography
ii. The role of chance
iii. The interaction of geography and chance - The theory of Island Biogeography
b. Island Biogeography
i. The effects of distance from the mainland
ii. The effects of island size
1. Islands, like all patches of habitat, need to be colonized
2. Ex. Krakatoa
c. Conservation implications
i. Habitat patches as Islands - what's the problem?
ii. Visualizing a patch - species/area relationships
iii. Implications for the design of reserves and refuges
iv. SLOSS (single large or several small)?
1. Wildlife corridors?
2. Edge effects