Exam 2 Flashcards
Define evolution.
change in gene frequency in a population
Define sexual selection and compare it to the more general term natural selection.
Sexual selection- form of natural slection where individuals with certain inherited traits are more likely to get mates.
In sexual selection, reproduction is improved by traits that don’t improve survival, including triats that actually hurt survival
Identify the difference between intersexual selection and intrasexual selection.
intrasexual selection- direct competition(fight) between individuals for sexual partners
intersexual selection- individuals (usually females) choose their sexual partners
List the forces of change in evolution. (Another way to ask this is, list the things that don’t change in a population that is not evolving.)
Natural selection
Migration
Gene mutation
Genetic drift: random accidents (Ex. Bottlenecking Event)
State the Hardy-Weinberg equilibrium equation.
p^2+ 2pq+ q^2= 1
The Hardy-Weinberg equation describes a population that is not evolving. Identify two things that happen after 1 generation of random mating.
- p(dominate allele) and q(recessive allele) don’t change
2. genotypic frequencies stabilizes
Define fitness.
In Darwinian terms, fitness means the ability to produce offspring
- Explain the relationship between genetic variation, inbreeding, bottleneck effect, genetic drift, and adaptation.
Genetic Variation- not everyone in the population is genetically the same. This is needed for natural selection
Inbreeding- When 2 closely related individuals mate. This is bad because close relatives share more genes, including recessive genes that are harmful in the homozygous condition
Bottleneck effect- a special case of genetic drift. Drift is the random loss of alleles from a population. It happens in small populations. Since natural selection has to have genetic diversity to select from, loss of alleles limits the possible results of selection.
Adaptation- genetic change due to natural selection that solves a specific problem
Compare and contrast species concepts
Morphological: physical similarities(body shape, color, etc.) defines a species; works for both asexual and sexual organisms
Biological: group that makes fertile offspring through sexual reproduction; doesn’t work for asexual org. and fossils; doesn’t take into consideration gene flow
Ecological: groups become species based on where they live/ type of Environment; good for asexual and sexual; takes into consideration of natural selection on how species interact in environment
Phylogenetic: grouped together based on common ancestors on tree of life; due to morph trait or molecular trait
Explain the biological species concept, and point out cases where it is difficult to apply.
Biological species concept groups a species based on their ability to make fertile offspring. It doesn’t apply to fossils or asexual organisms
List some mechanisms of reproductive isolation, and when in the life cycle of an organism they function
Prezygotic
Pre-Mating
Temporal(time) isolation: One wants to have sex at a certain time when the other doesn’t
Behavioral isolation: mating rituals are different
Habitat iso: same habitat but don’t meet each other
Post-Mating
Mechanical iso: mating is unsuccessful cus’ reproductive organs don’t line up
Gametic iso: sperm isn’t compatible with the egg and can’t survive
Post Zygotic
Offspring reduced Viability: zygote forms but dies in process
Hybrid(offspring) are infertile/sterile
Hybrid Breakdown: the hybrid is strong… but can’t produce fertile offspring
Contrast prezygotic vs. postzygotic isolation, and give examples.
Prezygotic isolation are mechanisms that prevent organisms from meeting, therefore preventing sperm and egg cells (zygotes) from meeting. Temporal, Behavioral, and Habitat isolation are examples.
Post zygotic isolation happens when organisms mate and have offspring… but the offspring are either sterile and nonviable (still born). The mule is an example, it’s naturally sterile, because it’s parents(the horse and donkey) aren’t closely related enough to produce fertile offspring.
Compare allopatric vs. sympatric speciation.
Allopatric speciation: a population is separated by a physical barrier (i.e land masses, large bodies of water). Meaning that a species that was once the same is now genetically different due to long term isolation.
Sympatric speciation: speciation that occurs without physical separation of members of a population. They are are able to mate and produce hybrids
Explain and give examples of adaptive radiation.
Adaptive radiation is when one species rapidly evolves into many. A classic example of this would be Darwin’s finches.
Describe the process of allopatric (geographic) speciation.
some force of nature( a flood, faults, etc) separates a once homogeneous species and diverges them from one another. New traits in the species emerge (due to natural selection) and these new traits separate them from one another.
