Descent w/ Modification
Natural selection acts on _____________, but causes __________ to evolve over time.
Individuals, Populations
Natural selection can only act on ____________ caused by a genetic component. Natural selection changes the percentage of alleles in a population, which changes the percentages of each _________ in the population.
(phenotype/genotype)
Natural selection can only act on phenotypes caused by a genetic component. Natural selection changes the percentage of alleles in a population, which changes the percentages of each genotype in the population.
Explain the difference between micro and macroevolution
Microevolution - changes in allele frequencies within a population between generations
Macroevolution - broad patterns of evolution through time
Name the causes of the following events:
1. The Permian Mass Extinction
2. The Cretaceous Mass Extinction
The Permian Mass Extinction was caused by an extreme episode of volcanism --> CO2 rose, global climate rose 6C, ocean acidification, nutrient enrichment of ocean leading to anoxic conditions
The Cretaceous Mass Extinction was caused by a massive meteor collision --> debris cloud blocked sun, causing a rapid drop in global temperature
What event differentiates between prezygotic and postzygotic reproductive barriers?
Formation of the zygote
What are the two principles of evolution that Lamarck proposed?
Use and Disuse, Inheritance of Acquired Characteristics
A new population of humans is established on an island. This population only has 6 individuals, two of which are carriers for an allele causing cystic fibrosis. After 10 generations, the allele becomes fixed and all individuals have cystic fibrosis.
What is this an example of? (Two answers)
Genetic Drift, Founder Effect
In a population of monkeyflowers, a few individuals in one generation have a mutation causing them to be tetraploids (have 4 sets of chromosomes instead of 2). These individuals can now only mate with each other and are reproductively isolated from the rest of the population. What type of speciation is this?
Sympatric speciation
Name the two types of hydrothermal vents that may be the origin of organic molecules on Earth. Which vents is more favorable to organic compounds?
1. Black Smoker Vents 2. Alkaline Vents
Alkaline vents more favored
In mammals, mammary glands that produce milk were co-opted from sweat glands. What is this an example of?
Exaptation
There are four main types of data that support evolution. What is one example of direct observations?
Antibiotic resistance, herbicide/insecticide resistance, species evolving due to invasive species
How does the effect of natural selection on fitness differ from other mechanism of change in populations (genetic drift, mutation, gene flow)?
Natural selection favors beneficial alleles in a population. Other mechanisms of change may increase harmful alleles in a population.
A common ancestor of two species of mollusks exists as one species for 30 million years. Then, in a period of 500,000 years the common ancestor quickly diverges into the two modern species. What is this an example of?
Punctuated equilibria
If RNA was the first genetic material, why is our genetic code made up of DNA?
DNA is more chemically stable and more easily replicated.
What are the three limitations of the biological species concept?
1. Cannot be applied to asexual organisms or fossils
2. Gene flow can occur between distinct species
3. Emphasizes separation rather than unity within species
Despite sharks being fish and dolphins being mammals, both have "torpedo-shaped" bodies to swim fast in water. What is this an example of?
Convergent evolution/analogy
In a population under Hardy-Weinberg equilibrium for a trait.
p = .65
What percent of the population is homozygous recessive at this genotype?
12.25%
Two species of iguanas can breed and produce a healthy hybrid offspring. However, the hybrid individual is unable to produce any offspring of its own. Is this a prezygotic or postzygotic barrier? What specific kind of reproductive isolation?
Postzygotic, Reduced hybrid fertility
An insect individual has a mutation where instead of antennas developing on their head, another pair of legs develops. The location of a __________ likely changed on one of their chromosomes.
Hox gene expression
An island is discovered in the Pacific Ocean and is believed to be about 25,000 years old. Human fossils are discovered on the island. What technique would you use to figure out the age of these fossils?
Carbon-14 Dating
A population of finches inhabits an island. Their primary diet is hard seeds, and a majority of finches have large beaks to eat seeds efficiently. A minority of finches has small beaks and can eat burrowing insects. A drought causes a majority of the plants to die on the island. Predict what will happen to the population of finches.
Beak size of the population will become smaller. Those with smaller beaks (variation) survive better on insects (differential success) and pass those traits to offspring (heritability).
A population of snails come in two color morphs: brown and gray. Birds preferentially eat the most common color morph in the population. So, each generation the population cycles between brown and gray being the most common color morph. What type of selection is this?
Frequency-dependent Selection
In a hybrid zone, hybrids typically have lower fitness than the parent species. If the hybrids have equal fitness with individuals of the parent species, what will most likely happen?
Stability of the hybrid zone
Paleontologists know which mammalian precursor (ancestor) was the first to have a differentiated teeth, but not which one was the first to have the modern reproductive system. Why is this?
Soft body tissues/organisms decay and lack hard structures to fossilize. Teeth/bones fossilize more easily.
A population of is under Hardy-Weinberg equilibrium for a trait. If q^2 for that locus is 9% of the population, what percent of the population is heterozygous for that locus?
42%