Types of Selection
Female birds that lay close to the optimum number of eggs have the most surviving offspring. Those that lay fewer or more eggs have lower relative fitness.
What type of selection?
Stabilizing
Domesticated reindeer in western Alaska escape and mate with migrating caribou, adding the alleles for short legs and calm behavior.
What type of evolutionary process is this?
Gene Flow
What is speciation?
When one species evolves into two separate species
What is the frequency of the recessive allele (q) if the dominant allele (p) frequency is 0.45?
q = 0.55
A population of Madagascar hissing cockroaches lives in a woodpile. The cockroaches are eaten by lizards. Because the lizards have small heads, the lizards are unable to eat the very largest adult cockroaches, and instead prey upon small and medium sized adults.
What type of selection is this?
Directional
Northern elephant seals have reduced genetic variation because of a population decline in the 1890s. Due to hunting, their population size was reduced to as few as 20 individuals at the end of the 19th century. Their population has since grown over 30,000 — but their genes still carry the marks of this decline: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.
What type of evolutionary process is this?
Bottleneck Effect
What is the difference between allopatric and sympatric speciation?
Allopatric is geographical and sympatric is behavioral
What does a phylogenetic tree show us?
How closely related a species is to another one
What is the frequency of the homozygous dominant genotype (p2) if the frequency of the recessive allele (q) is 0.3?
p2=0.49
Seed cracker birds have either large beaks or small beaks. They do not have medium sized beaks because medium sized beaks do not allow for adequate cracking of seeds.
What type of selection is this?
Disruptive
A few wolves were reintroduced into Yellowstone National Park. These wolves thrived and continued to grow their population size although they had low genetic variation.
What evolutionary process is this?
Founder's Effect
Two species of fireflies come out between the hours of 9-11 p.m. Each species has a unique pattern of flashes that attracts a mate.
What type of speciation is this AND why?
Sympatric because the flashing patterns is behavioral
How do you find a common ancestor of two species on a phylogenetic tree?
Find the two species and follow it down to where they intersect
What is the frequency of the heterozygous (2pq) if the frequency of the homozygous recessive geneotype (q2) is .36.
0.48
Describe fitness and give an example.
Describes an organism who is better suited to its environment
Examples may vary
Change this scenario to make it an example of gene flow: A few wolves were reintroduced into Yellowstone National Park. These wolves thrived and continued to grow their population size although they had low genetic variation.
New wolves joined a population of other wolves and reproduced, mixing the gene pools.
Two species of squirrels get stranded on either side of a grand canyon.
What type of speciation is this AND why?
Allopatric because the grand canyon is a geographical barrier
See Honors Natural Selection Jeopardy Images Slide 1
What traits does the crocodile have according to this phylogenetic tree?
four legs
amniote egg
Find the frequencies of p, q, q2, p2, and 2pq if 23 out of 100 cats show the recessive phenotype of white fur.
p= 0.52
q= 0.48
p2= 0.27
q2= 0.23
2pq= 0.5
Describe Natural Selection and give an example.
A mechanism of evolution where organisms better adapted to their environment tend to survive and pass those traits onto offspring.
Examples may vary.
Change this scenario to make it an example of Founders Effect:
A population of 5,000 island foxes lives on an island. A severe hurricane kills most of the foxes, leaving only 80 survivors. The surviving foxes reproduce, and over time the population grows again, but the genetic diversity remains much lower than before the hurricane.
A small group of 80 island foxes leaves the original island and colonizes a nearby uninhabited island. These foxes start a new population that grows over time. Because the new population was founded by only a small number of individuals, it has less genetic diversity than the original population.
Read the scenario and pick out what factors are causing speciation:
A population of insects lived in the same field, but some individuals began feeding only on one type of plant while others fed on a different plant. Over time, the groups mated only with insects that used the same host plant, eventually forming separate species despite living in the same area.
feeding behaviors (only one type of plant)
breeding behaviors (only breeding with insects that use the same plant)
See Jeopardy Images Slide 2
Fill out the phylogenetic tree based on the traits.
One student draws up front
Find the frequencies of p, q, q2, p2, and 2pq if 63 out of 100 cats show the dominant phenotype of black fur.
p= 0.39
q= 0.61
p2= 0.15
q2= 0.37
2pq= 0.48