Test 1 study

Question 1

Define natural selection and explain ‘fitness’

Answer 1

NS is the process in which individuals have inherited traits that allow them to survive/reproduce more because of those traits

Question 2

why is natural selection not random and not goal-directed

Answer 2

natural selection doesn’t produce organisms perfectly suited to their environments. it allows the survival of individuals that are good enough. mutation causes genetic variation and is completely random

Question 3

how is artificial selection evidence for evolution?

Answer 3

because it provides us with a model that helps us understand natural selection- selecting for specific traits

Question 4

how are homologous structures evidence of evolution?

Answer 4

shows that some species derived from a common ancestor

Question 5

how are vestigial structures evidence of evolution?

Answer 5

shows that some organisms used to have structures that are no longer of use
ex. hip bones in whales

Question 6

how is convergent evolution evidence of evolution?

Answer 6

shows that organisms will adapt to their environments

ex. wings in many different organisms

Question 7

how does biogeography show evidence of evolution?

Answer 7

shows that some organisms have been in environments on earth but have since diverged from the original population- they used to be together

Question 8

what is the difference between homologous and analogous structures?

Answer 8

(H) are similar in structure but differ in function- they share a common ancestor, while (A) are structures in organisms that don’t share a common ancestor but have structures that share similar functions

Question 9

what is microevolution?

Answer 9

microevolution is evolutionary change below the species level; change in allele frreq. in population over generations
ex. bacteria building resistance to pesticides

Question 10

what is macroevolution?

Answer 10

evolutionary change above the species level

ex. ex. human to ape, bird to dinosaur

Question 11

what are...
(A) alleles
(b) genes
(c) genotypes
(d)phenotype
(e) dominant 
(f) recessive
(g) heterozygous

Answer 11

(a) any version of a gene that may produce distinguishable phenotypic effects
(b) unit of hereditary info consisting of a specific nucleotide sequence in DNA
(c) genetic makeup, set of alleles in an organism
(d) observable physical traits
(e) fully expressed allele in a heterozygote
(f) allele not expressed in a heterozygote
(g) organism that has 2 different alleles for a gene

Question 12

the ultimate source of variation is wha?

Answer 12

mutation

Question 13

what conditions need to be met for a pop. to be in H-W equilibrium?

Answer 13

• large populatio
• random mating
• no natural selection
• no immigration/emmigration
• no chnage in allelic freq. due to mutation

Question 14

What are the H-W equilibrium equations, and what do the variables represent?

Answer 14

Allele freq. (p+q=1)
genotype freq. (p^2+2pq+q^2=1)
p= all dominant alleles
q= all recessive alleles
p^2= homo dom. freq
q^2= home rec. freq
2pq= hetero freq

Question 15

Define and give examples of the two types of genetic drift

Answer 15

genetic drift is when chance events cause fluctuations in allele freq. from one gen to the next

founder effect- when a few indiviuals from a population become isolated and form a new population
bottleneck effect- when the size of the population is reduced, as by a natural disaster of human actions. typically the surviving pop isn’t representative of the original population

Question 16

what is directional selection?

Answer 16

directional selection is natural selection that in which one extreme of the phenotypic range survives/reproduces more sucessfully than others

Question 17

what is disruptive selection?

Answer 17

natural selection in which both extremes of the phenotypic range survive and reproduce more sucessfully than the intermediate

Question 18

what is stabilizing selcetion?

Answer 18

natural selection in which the intermediate of the phenotypic range survives and reproduces most sucessfully

Question 19

what is the biological species concept?

Answer 19

a definiton for species as a group of population whose members have the potential to interbreed in nature and produce viable offspring, but not with other such groups

Question 20

what is the morphological species concept?

Answer 20

def. of species in terms of measurable anatomical criteria

ex.

Question 21

what is the phylogenetic species concept?

Answer 21

species are an irreducible-(not to be reduced or simplified) group whose members are descended from a common ancestor and who all possess a combo certain defining, dervied traits

Question 22

why isn’t the biological species concept perfect?

Answer 22

• ignores asexual organisms
• ignores isolated populations
• ignores hybridization
• fossils (no actual evidence of sex)

Question 23

what is a sympatric species?

Answer 23

formation of new species in populations that are in the same geographic area- flies that either fed off of apples or blue berry

Question 24

what are the reproductive isolation mechanisms?

Answer 24

habitat iso- species that occupy the same area but don’t interact
temporal iso- breed during different times
behavioral iso- diff breeding rituals
mechanical iso- mating is attempted but morphological diff prevents breeding
gametic iso- sperm cant survive/be fertilized by egg of other species
reduced hybrid viability- hybrid has impaired development that reduced its ability to survive
reduced hybrid fertility- hybrid offspring can’t reproduce
hybrid breakdown- 1st gen of hybrids are viable and fertile but every later generation increasingly becomes less fertile and viable

Question 25

What is the difference between allopatric and sympatric speciation?

Answer 25

sym- speciation in the same area

allo- speciation in species that are geographically isolated from each other

Question 26

What is a hybrid zone? What are the possible outcomes in hybrid zones, and what mechanism might lead to each of these outcomes?

Answer 26

hybrid zone- A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.
outcomes include:
Reinforcement- strengthening of reproductive barriers
fusion- weakening of reproductive barriers
stability- continued production of hybrid individuals

Question 27

Does natural selection increase or decrease variation?

Answer 27

decrease