Evolution
What is punctuated equilibrium and gradualism in terms of evolution?
Punctuated equilibrium - there isn't a lot of change for a while and then there's suddenly a lot of change
Gradualism - the environment changes slowly and steadily, causing slow and steady evolution
What are the five main pre-zygotic barriers that will lead to speciation?
1. habitat isolation
2. temporal isolation (different mating seasons)
3. behavioral isolation (different courtship mechanisms)
4. mechanical isolation (reproductive structures don't line up
5. gamete isolation (sperm cannot fertilize egg)
How did the first cell form? Was it anaerobic or aerobic, heterotrophic or autotrophic?
it most likely formed from a random assortment of organic molecules and enzymes that were confined in a lipid bubbles (kinda like sea foam)
It was an anaerobic heterotroph
Explain what each of these variables is in the Hardy Weinberg Equation:
p, q, p^2, q^2, 2pq, p^2 + 2pq
p - dominant allele frequency
q - recessive allele frequency
p^2 - frequency of homozygous dominant
q^2 - frequency of homozygous recessive
2pq - frequency of heterozygotes
p^2 + 2pq - frequency of the dominant phenotype
What are four ways that scientists have found evidence for evolution?
1. Direct Observation(ex antibiotic resistance)
2. Fossil Record
3. Comparative Anatomy and Physiology (homologous and vestigial structures)
4. Comparative Molecular Biology
What are the three main post zygotic factors that isolate different species?
2. hybrid sterility (zygote is sterile)
3. hybrid breakdown (F1 generation is viable but following generations are not)
What are the two smaller processes that contribute to genetic drift?
The bottleneck effect - a large population is suddenly reduced to a smaller one, not always a representative sample
The founder effect - a small subset of a population moves to an isolated habitat, not always a representative sample either.
What are the three conditions for natural selection?
2. genetic variation
3. some phenotypes have a selective advantage over others
Define and give an example of analogous structure, a vestigial structure, and a homologous structure
analogous - similar structures in different species that are not the result of evolution(ex: whales and sharks)
homologous - parallel structures as a result fo something present in a common ancestor ( ex: bone structures in whales, humans, and bats
vestigial - obsolete features that serve no purpose (leg bones in whales)
What is the difference between allopatric and sympatric speciation?
When reading a cladogram or phylogenetic tree, explain the significance of outgroups and shared derived characteristics
outgroup- lineage that is least related to all the other organisms
shared derived characteristic - trait in a group of species that evolved from a common ancestor, normally. not present in the organisms of the entire cladogram
What are the four types of selection (this about the graphs of before and after)? Explain each one and give an example
Directional Selection - shift towards one extreme
Stabilizing Selection - average phenotype is favored
Disruptive Selection - both extremes are favored
Frequency-Dependent Selection - a phenotype is only advantageous when it is at a certain frequency (most likely rare)
Explain coevolution and convergent evolution.
coevolution - species evolve together, impacting each other (bees and flowers)
convergent evolution - two unrelated species wind up looking similar because of similar environments
What is genetic drift?
This is a random change in the frequency of a particular allele than usually happens in small populations
What are the two hypotheses for how complex organic molecules came to exist on Earth?
1. Complex Molecules formed from simpler ones as a result of the conditions of early Earth (lots of energy, not a lot of 02)
2. Complex molecules were brought here by meteorites
What are the 5 conditions for Hardy Weinberg?
1. large population (no genetic drift)
2. absence of migration - no gene flow
3. no net mutation - no genes are modified, deleted or duplicated4. random mating - no sexual selection
5. no natural selection
Explain how polyploidy happens and how it can lead to speciation
When polyploidy happens due to nondisjunction in meiosis, the F1 generation (polyploid) has a different number of chromosomes than the rest of the population. Because of this, it is unable to mate with its parent species and therefore becomes a new species.
What is the "RNA world" hypothesis?
What are four ways that populations increase their genetic variation?
1. literally transferring genes from one organism to another
bonus - through transformation(free DNA), transduction(through virus), conjugation(cell-cell DNA transfer), and transposition(movement of DNA segments within the same molecule)
2. sexual reproduction
3. independent assortment
4. crossing over during meiosis