Download SI - TEST 1 STUDY GUIDE Bio 203 – Spring 2011 Introductory

SI - TEST 1 STUDY GUIDE
Bio 203 – Spring 2011
Introductory Material
Fitness:
Natural selection:
Evolved trait:
*Any trait can be beneficial, neutral, or detrimental to individuals or species
Adaptation:
Good of the species fallacy:
Wrong. Why?
Example: Call in the male Tungara Frog, a case of female mate choice driven sexual
selection
Adaptation –
Females prefer which condition (and why) –
How is this adaptation “bad for the individual/species”?
If this adaptation is detrimental to both males and females, why does it exist?
Example: Toxins in ejaculate of the male drosophila, a case of sperm competition driven
sexual selection
Adaptation –
How is this adaptation “bad for the individual/species”?
If this adaptation is detrimental to both males and females, why does it exist?
Sperm competition in humans
“Win it”:
Draw a graph depicting the relationship between ejaculate size and time apart
since last copulation
“Prevent it”:
Examples (4)-
Naturalistic fallacy:
Wrong. Why?
Examples of statements that commit the naturalistic fallacy:
- “The barnyard animals’ heterosexuality gives moral guidance and shows
homosexuality to be immoral.”
- Infidelity undermines the natural state of marital monogamy and thus it is
morally wrong.
- Infidelity is biological and hence it is morally good.
- Homosexuality is biological and therefore homosexuals should be allowed to
marry.
- Heterosexuality is natural and therefore homosexuals should not be allowed to
marry.
- Red jungle fowl and male scorpion flies have a rape adaptation and this
justifies men’s raping.
- HIV is evolved and therefore its spread should be promoted.
- The most common mating system across human societies is harem polygyny –
it is nature’s way – and should be encouraged and legalized in the US.
- What is natural determines what is ethically correct.
- Any human behavior that is genetically caused is morally right.
Defining Evolution, Mutation, Causes
1. Change in _____________ frequency across generations.
2. Change in _____________ frequency across generations.
Example: HIV resistance to AZT, describe the course of evolution for this trait
* All evolution involves both definitions of evolution
* Trait changes (phenotypic plasticity) can occur across generations without changes in allelic
frequencies  this is not evolution
Mutation:
Does mutation occur frequently?
Mutations are random. Explain how this is so when environmental stressors cause
mutations.
What happens when the selection pressure for an adaptation is removed?
Causation of traits
Ultimate cause:
Example: HIV resistance to AZT –
Example: Songs in male mockingbirds –
Proximate cause:
Example: HIV resistance to AZT –
Example: Songs in male mockingbirds *When the trait is very rare, the only ultimate cause is mutation (NOT selection)
Example: Blue-skinned rock lobster
What might explain a maladaptive trait whose frequency is low, but higher than
mutation-selection balance?
Example: Schizophrenia
This phenomenon, is due to ________________________.
A special case: sex-limited adaptations:
Heritability (4/2)
Heritability:
Total phenotypic
variation among
individuals for a trait
% variability
among individuals
in a trait due to
genetic differences
% variability among
individuals in a trait
due to environmental
differences
Example: Variation in human = 0.5 due to genetic + 0.5 due to environmental
height
differences
differences (quality and amount
of food, disease, etc.)
Inheritance ≠ heritability
Inheritance:
Occurs when _________ causes of the trait and __________ causes of the trait
are repeated across generations.
Drift, Complex Traits, EEA
Drift:
*When alternative traits and associated alleles are selectively neutral, drift determines the
evolution and frequency of traits and alleles.
Provide a hypothetical example of when drift causes evolution:
*Drift is most effective for bringing about evolution in small populations
A side note about small populations: inbreeding depression
Inbreeding depression:
*Humans avoid inbreeding with co-socialized intimates
What is one hypothesis that explains why humans inbreed at all?
How would we test this hypothesis?
Selectively neutral traits:
Complex traits
Examples:
*Complex traits are a result of past selection, but not all complex traits are adaptations.
Traits directly selected  adaptations
Traits indirectly selected  incidental effect (byproduct)
*Complex traits are not the result of drift
EEA (environment of evolutionary adaptiveness):
Under what conditions might adaptations be considered maladaptive?
So, it follows that an adaptation will be currently adaptive only when…
Give three examples where adaptations are currently maladaptive.
-
Ewald on HIV
According to Ewald, what accounts for the selection for virulence in HIV?
High reproductive rate = high/low virulence = early/late host death = high/low rate
of transmission
Low reproductive rate = high/low virulence = early/late host death = high/low rate
of transmission
What accounts for the difference between the development of HIV-1 in heterosexuals of eastern
and southern Africa, and HIV-2 in heterosexuals of western Africa? (in terms of transmission
rates)
According to this hypothesis, what should be done to control the AIDS pandemic?
Homology, Analogy, Parsimony
Homology:
Describe three lines of homological evidence for the relatedness of chimpanzees and
humans
What is the proposed progression of chimp SIVHIV-1?
Parsimony:
Why should we use parsimony in constructing phylogenetic trees?
How do complex traits challenge the principle of parsimony?
Example: Mammary glands in mammals
Example: Fatty depots in female humans, a case of sexual selection and analogy
What are the two kinds of fat female humans possess? Their functions?
How is this trait sexually selected for?
Phylogenetic Trees
C
E
D
B
A
*Species are more closely related when they share a more recent common ancestor.
Example: The Yellow-eyed penguin is more closely related to the Rockhopper penguin
than it is to the Galapagos penguin
 Yellow-eyed penguin : Rockhopper penguin common ancestor at A,
which occurs more recently than…
 Yellow-eyed penguin : Galapagos penguin common ancestor at B
*A clade (AKA: monophyletic group) is composed of one species and all of its descendent
species
Example: King penguin, Emperor penguin, ancestor species at C
 Ancestor species C gave rise to both the King penguin and the
Emperor penguin, but no other species
Example: Adelie penguin, Gentoo penguin, Chinstrap penguin, D, E
 Ancestor species E gave rise to the Adelie penguin and ancestor
species D, which gave rise to the Gentoo penguin and the Chinstrap
penguin
 Ancestor species D, Gentoo penguin, and Chinstrap penguin can also
be described as a clade
GOOD LUCK!!!
Suggested Vocabulary
Good of the species fallacy, natural selection, fitness, adaptation, evolved trait, reproductive
success, nonrandom differential reproductive success, random differential reproductive success,
sexual dimorphism, sexual selection, honest signal, female mate choice, sperm competition, pairbonding, mate guarding, naturalistic fallacy, biological, natural, evolved, HIV, AIDS, T cells and
macrophages, special-purpose, evolution, phenotypic plasticity, mutation, ultimate cause,
proximate cause, sex-limited adaptation, mutation-selection balance, heritability, inheritance,
drift, selectively neutral traits, gene flow, inbreeding depression, EEA, homology, analogy,
morphological homology, behavioral homology, genetic homology, physiological homology,
homologous traits, phylogeny, node, branch, zoonotic disease, human-specific disease,
cladogram, parsimony, taxonomy, lineage-specific selection, convergent evolution, divergent
evolution, monophyletic, paraphyletic, speciation
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