exam 4 Flashcards
True or false: Evolution is a linear process resulting in a single optimum
False
True or false: Humans evolved from chimpanzees
False
Humans and chimpanzees are _____________
evolutionary cousins
Evolutionary cousins definition
ancestor that was not either of the species being looked at
True or false: Humans are highest on the tree of life
False (humans are not more evolved than other living organisms)
Theory definition
a statement of what are held to be the general laws, principles, or causes of something known or observed
True or False: Evolution of complex societies is dictated by selfish genes
False
What is altruism in complex societies?
Individuals behave in such a way that increases the survival or reproductive success of other unrelated members of the group at the expense of their own survival or reproductive success
True or False: Natural selection is the main driving force in evolution
False
Forces in evolution
genetic drift & natural selection
Phenetics
Method of classifying organisms based on overall similarity
Alligators are more closely related to _____ than _____
birds ; lizards
Taxonomy
the science of classifying living organisms, usually hierarchical in structure
Phylogenetics
the study of historic relatedness among groups of organisms (eg. species, populations)
Phylogeny
The evolutionary relationships between a set of organisms, usually species
Systematics
the study of the diversity of organism characteristics, especially how they relate to establishing a phylogeny
Primitive Character (ancestral or plesiomorphic)
character inherited with little or no change from remote ancestors
Derived Character (apomorphic)
character that has undergone recent change
Symplesiomorphic
Primitive character shared by several species
Synaptomorphic
derived character shared by 2 or more species
Cladogram
a pictorial representation of the evolutionary relationships of organisms according to the principles of cladistics
Clade
branch in a cladogram
Monophyletic group
a group of organisms which shares a common ancestor and which includes the ancestor and all its descendants
Taxon
a grouping of organisms
Cladistics
method of classifying organisms based on shared derived characters
Why does allele frequency change from generation to generation without any natural selection?
- even if they are fit, not all organisms in the population survive and reproduce
- the process of meiosis ensures that an individual does not pass on all their alleles, only half for each reproductive event
Why is genetic drift important to consider?
Major driving force in speciation (cichlids in the river)
The smaller the population size the _______ genetic drift will cause __________
faster ; divergence
Evolutionary adaptation
A feature which has evolved via natural selection to improve a specific function and increases fitness (survival or reproductive success)
Neuroadaptation
a relatively long-lasting change in the brain that occurs in response to an environmental stimulus (eg. long term potentiation)
Physiological adaptation
a change in physiology that enables the animal to acclimate to a changing environment (eg. reduced pulse rate in response to regular exercise, increased red blood cells after living at high altitude)A
Adaptation can be defined based on
current function and utility and/or historical origin
Preadaptation
possession of the necessary properties to permit a shift into a new niche or habitat. A structure is pre-adapted for a new function if it can assume that function without much evolutionary modification
Selection is always occurring, so organisms are constantly evolving towards
a state of better adaptation
Natural selection has been seen by most as the major force in evolution because adaptive evolution by natty selection seems to be inevitable given:
- individual variation is always present which affects fitness
- most traits are heritable
The adaptationist programme
- organisms are reduced to traits
- traits are explained as optimally designed by natural selection for their functions
- “trade offs” lead to the best compromise among competing demands
In addition to natural selection, the main factors that affect evolution are
- random mutation
- genetic drift
- sexual selection
- contraints and tradeoffs
- bauplan; inheritance or phylogenetic inertia
Bauplan (phylogenetic inertia)
the idea that the organism cannot be reduced to a series of traits each of which are subject to natural selection and adaptation
Alternatives to adaptation
- genetic drift (no adaptation and no selection)
- side effects and spandrels (no adaptation and no selection on the part at issue)
2 main approaches to identifying adaptations
- the comparative method
- selection experiments
Comparative method definition
look across species and choose ones that vary across environments, then observe their traits
Selection experiments definition
Selective breeding
Evidence citing male superiority in spatial navigation
- way-finding tests of navigation
- mental rotation tests
- males score higher on SATs
- cross cultural
- testosterone enhances spatial performance
Testosterone side effect hypothesis
testosterone evolved in males to produce primary (penis, testicles) and secondary (muscles, chest hair) sex characteristics. It has side effects (baldness) that do not harm the male and therefore constituted a sufficient solution
Problems with adaptationist theory
bauplan, inter-gender hitchhiking
Intergender Hitchhiking
In general, directional selection on one sex will lead to a correlated response in the other, except under special circumstances when what is good for one sex is bad for the other
Adaptationist theory #1 for the female orgasm
Orgasms evolved because they give females a reward and motivation to engage in frequent intercourse
Problem with “Orgasms evolved because they give females a reward and motivation to engage in frequent intercourse”
It assumes that intercourse is reliably connected to orgasm in females. All the clinical evidence suggests that a majority of women do not experience orgasm with unassisted intercourse
Adaptationist theory #2 for the female orgasm
Orgasms evolved to suck sperm in
Adaptationist theory #3 for the female orgasm
Female orgasms have a special function related to bipedalism because they increase the chance of fertilization. After orgasm there is a considerable period of rest and relaxation
Problem with “
