Natural Selection
One of the biggest ways that a species evolves is because some organisms with some traits survive and reproduce better than others. This process is known as
Natural Selection
Which pattern of evolution does this describe?
Multiple species evolving from a common ancestor
Divergent Evolution
Scientists can explore whether two different animal species have evolved from a common ancestor, using evidence from all of the sources below except
a. analysis of strands of DNA
b. comparisons of bones and muscles
c. comparison of the experiences of each organism
d. studies of embryos during development
c. comparison of the experiences of each organism
What do all organisms on a phylogenetic tree have in common?
a common ancestor
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.4. What is the percentage of the population that is a homozygous dominant genotype?
36%
During a period of droughts in the Desert, seeds that are small and easily eaten become rarer, leaving mostly seeds that are large with hard-cased shells behind. The only birds that can eat these particular seeds are those with large beaks. If the drought continues for several more years, what should be expected to happen as a result of natural selection?
More small-beaked birds will die than larger-beaked birds. The offspring produced in the following generations will have a higher percentage of birds with larger beaks.
Which pattern of evolution does this describe?
Burst of evolutionary change followed by periods of stability.
Punctuated Equilibrium
Early during development, organisms as diverse as a human, a mouse, and a bat can appear indistinguishable. All of their embryos look nearly identical, suggesting that
a. during development, humans go through stages of being a mouse and a bat
b. similar structures have developed because of convergent evolution
c. these very different species have a shared ancestry with all mammals
d. this is coincidental resemblance between them
c. these very different species have a shared ancestry with all mammals
According to binomial nomenclature, species are given two names based on their ______ and _______.
genus and species
In a neighborhood lagoon, there is a population of 60 alligators. Of those 60 alligators, 12 of them show the recessive trait for small teeth. List the expected frequencies of the dominant and recessive alleles. Assume Hardy-Weinberg Equilibrium.
q = .45
p = .55
Most robins produce 4-5 eggs at a time. Those robins that produce fewer or more than this have reduced fitness. This describes what type of selection?
Stabilizing Selection
Which pattern of evolution does this describe?
Formation of a new species from a pre-existing species.
Speciation
Ostriches have wings, but do not fly. Humans have an appendix with no apparent function. Whales contain bones for rear legs. Each of these are examples of
vestigial structures
List the correct hierarchy of classification, going from broadest to most specific.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Grey skin color (G) is dominant to white skin color (g) in dolphins. In a population of 500 dolphins in the Port Royal Sound, 100 are gg, 225 are Gg, and 175 are GG. List the expected frequencies of the dominant and recessive alleles. (Note: these are REAL population numbers so you cannot assume Hardy Weinberg.)
q= .425
p = .575
What is ONE advantage and ONE disadvantage of peacocks having long tails?
Advantage: easier to attract a mate
Disadvantage: more easily seen by predators, tail is hard to carry around
Which pattern of evolution does this describe?
When two organisms evolve in response to the other.
Coevolution
Two bodily structures, found in different species, have different internal bone structures but serve a similar purpose in each organism. This is most likely describing
analogous structures
What are 2 pieces of evidence do scientists use to create phylogenetic trees
shared morphology, genes, and behaviors
The ability to taste PTC is due to a single dominant allele "T". You sampled 215 individuals and determined that 150 could detect the bitter taste of PTC and 65 could not. Calculate the percentage of the heterozygous population.
50%
A forest has many trees and bushes that produce nuts. This a major food source for many species, including a particular bird. Birds of this species have a variety in beak shapes ranging from long and pointy to short and hard. The birds with short and hard beaks are able to eat the nuts better than the birds with long and pointy beaks. What do you expect to happen to this population of birds over time, in terms of what you know about evolution? Include all 4 principles of natural selection in your explanation.
More birds than food will create competition for limited resources. Some birds have shorter beaks, and others have long and pointy beaks = variation. Short beaks are adaptations that help the birds in this environment survive. Because of this, over time birds with short beaks should live longer, and thus reproduce more, than other birds so that short beaks become more common = descent with modification
The red fox lives in mixed farmlands and forests, where its red color blends in with tree bark. The kit fox lives on the plains and in deserts, where its sandy color conceals it from predators. The ears of the kit fox are larger than the red fox to increase surface area to release heat. Similarities in structure indicate that the red fox and kit fox had a common ancestor. Is this convergent or divergent evolution?EXPLAIN
Divergent evolution because common ancestor, different color due to evolving in different environments
List two of the five fields of science discussed in class and why/how they provide evidence for evolution
Paleontology = Study of prehistoric life through the fossil record
Morphology = Study of the form of living things
Biogeography = Study of the geographic distribution of plants and animals
Embryology = Study of embryo development
Biochemistry = Study of chemical processes in living things
What are the 3 things we can learn from a phylogenetic tree?
1. which groups are most closely related
2. which groups are least closely related
3. which groups diverged first
Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the Caucasian population of the United States. Calculate the frequency of the recessive allele
.02