biology study sheet 14

What are ecological isolation, temporal isolation, behavioral isolation and mechanical isolation?

all prezygotic barriers eco- two groups of organisms live in the same general area but occupy different portions of that area temporal- when a couple groups of orgs create at different times (seasonal, night and day) behavioral- has to do with mating dances, if they aren't performing the right mating dance the female will not want to mate mechanical- when some kind of physical barrier prevents successful mating or gene flow (ex. flowers that evolve landing pads for different species of bees)

What is the difference between analogous and homologous structures?

analogous- similar appearance, but different origin homologous- different appearance, same origin

What are some vestigial structures in humans?

appendix, tonsils, tailbone

What are the three forms of natural selection?

directional- kills one extreme balancing- keeps polymorph balanced, preserves alleles disruptive- kills intermediate: eggs and sperm

What kinds of evidence support the existence of microevolution?

drug resistance and evolving to use new food sources skin color

What is frequency-dependent selection?

form of balancing selection that occurs when the fitness of a given phenotype increases, or decreases, based on its prevalence relative to alternative phenotypes within a population

What are the 4 main lines of evidence that indicate that macroevolution has occurred?

fossil record dna record comparative anatomy embryology tends to retrace evolutionary history

What is a species cluster, and what are some examples of species clusters?

fruit flies in hawaii, silverswords, fish in lake Victoria (over 500 species) thousands of species evolved from one

What is a molecular clock?

genes that tend to evolve at fixed rates

Why is it important to preserve genetic polymorphism, and what factors tend to preserve it?

heterozygous advantage and the need for multiple alleles for natural selection factors: diploidy and balanced polymorphism and frequency-dependent selection

How are we presently dramatically changing the evolution of life on earth?

humans are causing another mass extinction

What are the two most important postzygotic isolating mechanisms?

hybrid inviability and hybrid sterility

Why can polyploidy result in the formation of a new species?

if the organism is capable of self fertilization, then the only org that can successfully go through meiosis can create a new species

What is the basic idea used to define a species, and why is this a problem?

if two organisms can reproduce sexually and have fertile offspring then they're the same species, but if they aren't they are a different species problem: it takes a long time to find out if they aren't fertile or fitter than either parent

What is industrial melanism?

industrial melanism in peppered moths before the industrial revolution moths were light. when industrial revolution hit and trees were coated in soot, moths went dark to blend in with trees

Why do we think that the frequency of sickle cell anemia is much higher in central Africa?

it is correlated with the presence of malaria the sickle cell anemia protects against malaria

Since sickle cell anemia is usually lethal, why hasn't it been eliminated by natural selection?

it protects against malaria which is also present it is a heterozygous allele individuals that are heterozygous are much more likely to have offspring that are homozygous for hpa or hps allele

What does "embryology retraces phylogeny" mean?

many organisms tend to retrace their fossil history as they develop from the fertilized egg

What is sexual selection?

mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex

How have the selective agents that affect humans changed "recently?"

mutation rate has increased gene flow has gone up genetic drift has gone down fewer old diseases and birth defects less famine new selection of diseases car crashes, birth control

Why do new species arise?

nature hates empty niches

What is "adaptive radiation?"

new species arising from an individual that arrived in an area where there are many empty niches

What is a niche, and what is a habitat?

niche- role in nature that a specific species fills habitat- type of environment where organisms live

How do you measure p2, 2pq and q2 by PCR?

no dominance or recessive. tells you exactly what the large allele is and what the small allele is

How can sympatric speciation occur?

organisms in the same species/area can't breed happens frequently in plants

What are the most common agents of selection?

predators, prey, parasites, poisons, climate, females

What is balancing selection, and what is a balanced polymorphism?

preserves two or more alleles and polymorphism. balanced polymorphism is one that is preserved

What are the two classes of barriers to hybridization?

prezygotic- preventing zygotes from forming postzygotic- can form but resulting individuals don't have offspring of their own

What is the best example of microevolution in human beings?

sickle cell anemia

What is a vestigial structure?

structure that no longer serves a purpose ninth organism that has it it served a purpose on an ancestor but hasn't been removed by natural selection

What is an ecotype?

subgroups of a population of organisms differences, genetic bases for these differences ecotypes: Polynesian, caucasian, African

What is a species?

the basic unit of taxonomy

What is kin selection and what is altruism?

the evolutionary strategy that favors the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction altruism- behavior that harms individual but helps relatives

What is convergent evolution?

the fact that similar environments tend to select for similar adaptations

Why are hybrids important for the evolution of new species?

the phenomenon of hybrid vigor the hybrid is superior to the parents so if they could pass on genes they might be capable of taking over

Why do humans living in tropical regions have dark skins while those in the north have light skins?

they are closer to the equator and have more daylight have more melanin to protect from the UV

Why have mass extinctions been important for evolution of life on earth?

they are opening up niches that were formerly occupied

What is "allopatric speciation?"

two populations separate by a geographical barrier

Why is comparative anatomy useful for studying evolution?

we can see the common origin by comparing anatomy can't put too much emphasis on comparing anatomy because it can change in weird ways

What is the fossil record and how is it used?

when organisms die and fall into water, they get buried into sediment and their bones get turned to stone we can study these fossils and see progressive changes in organisms over millions of years ages can be determined, different stages we can see how each organism follows the previous one

Why did the number of brightest guppies vary when you changed the numbers of predators?

when there were none the guppies tend to get brighter, but in the presence of predators the male guppies were more likely to get eaten so the more brightly colored guppies didn't survive long enough to mate with female and the females had to mate with dull guppies

Why did p and q change more rapidly when you selected against the dominant?

when you select against the dominant phenotype you are selecting against all individuals (homo and heterozygous), but when you select against recessive allele, you are only removing homozygous recessive individual so the dominant allele will persist

What are the usual steps to speciation?

-creating different ecotypes -some kind of barrier prevents gene flow (reproductive isolation) -make hybridization barriers

After doing PCR on students from several labs, we obtained 20 homozygous large bands, 76 heterozygotes and 4 homozygous small bands. What is the frequency of the small allele? A. 0.42 B. 0.2 C. 0.80 D. 0.04 E. 0.38

A. 0.42

The necessary ingredient for the evolution of a new species is A. reproductive isolation B. directional selection C. adaptive radiation D. nonrandom mating E. migration

A. reproductive isolation

Your population has these genotypic frequencies: AA = 1/9, Aa = 4/9 and aa = 4/9. If you remove all aa individuals what will be the frequency of F1 AA individuals? A. 0 B. 1/25 C. 9/25 D. 1/9 E. 1

C. 9/25

Why is inbreeding unwise? A. It increases the frequency of individuals homozygous for adaptive dominant alleles B. It increases the frequency of individuals homozygous for adaptive recessive alleles. C. It increases the frequency of individuals homozygous for harmful recessive alleles. D. It increases the frequency at which mutations occur during DNA replication. E. It increases the frequency of unequal crossing over.

C. It increases the frequency of individuals homozygous for harmful recessive alleles.

In a population of bears, which is the fittest? A. The strongest, fiercest bear B. The bear that blends in with its environment the best C. The bear that leaves the most descendants D. The bear that can do the most pushups. E. The bear with the largest number of mutations

C. The bear that leaves the most descendants

In the past century humans have traveled much more extensively than in previous generations. This has altered human evolution by increasing A. Nonrandom mating B. Mutation rates C. Genetic drift D. Gene flow E. Natural selection

D. Gene flow

Selection that removes one extreme from an array of phenotypes is called A. genetic drift B. stabilizing selection C. disruptive selection D. directional selection E. balancing selection

D. directional selection

Differential reproduction due to variable success in obtaining mates due to combat or courtship is: A. artificial selection B. sympatric speciation C. reproductive success D. sexual selection E. hybridization

D. sexual selection

Some small towns in Virginia have remained isolated and inbred since their settlement many years ago. The frequency of some alleles is much higher in these towns than in the rest of the US because of: A. artificial selection B. directional selection C. disrupting selection D. Hardy-Weinberg principle E. founder effect

E. founder effect

In the eastern U.S., two species of spiderwort (Tradescantia) do not interbreed because they bloom at different seasons. This is an example of A. behavioral isolation B. ecological isolation C. geographical isolation D. mechanical isolation E. temporal isolation

E. temporal isolation

How can DNA be used to study evolution?

Identifying regions that are uncommon and lining them up and counting the differences in the sequences we can estimate how long its been since a common ancestor

What are RFLPs and STRs and what are they used for?

STR- simple sequence from 1-7 base pairs repeated over and over again stay the same within a family but vary between families very effective for dna fingerprinting.

Why do we expect that the frequency of the CCR5 ∆32 allele will increase in humans?

The allele helps prevent infection from there HIV virus that causes AIDS