Download APbioReviewchapter 22-24 26 woodlice hardy weinberg and chi

1. What is natural selection: the main mechanisms of evolution,
the environment selects which traits are “fit” to survive, traits
that are best adapted for the environment survive and the others
are selected against
2. What are the four points of natural selection: there is variation,
species overreproduce, competition for resources, natural
selection is always working
3. Woodlice: longer the animal, faster sprint speed because more
likely to be seen by a predator so have to be faster
Small woodlice: smaller size hard to catch, tended to roll
because they weren’t fast enough to get away.
4. Hardy-Weinberg equation: p2 +2pq + q2 =1
p= dominant allele
q= recessive allele
p2 = homozygous dominant trait
2pq= heterozygous (dominant) trait
Q2 = homozygous recessive trait
5. Conditions for hardy-weinberg to be true:
Large population size, random mating, no mutations, no gene
flow, no natural selection
6. Evolution: gradual change in heritable characteristics in an entire
species over time
7. Speciation: the process by which new species develop
8. Allopatric vs. sympatric speciation: allopatric speciation involves
a population being separated by a geographic (physical) barrier,
the two populations adapt to the new environment over time,
eventually are separated long enough to be distinct species;
sympatric a small population becomes a new species without
geographic isolation
9. Evidence for evolution: direct observation, fossils, homologous
structures, analogous structures, biochemistry (DNA, enzymes),
vestigial structures, comparative embryology
10. Fossils: remains/traces of once living organisms; found in
sedimentary rock in the strata (layers); the deeper the layer the
older the fossil unless something occurs to disrupt the layers
11. Homologous structure: common ancestry but could have
different function (bat wings, bird wings, flippers, arms)
12. Analogous structure: not a common ancestor but derived
function (similar function) because the environment selects for
this (bird wings and insect wings)
13. Vestigial structures: structures that remain with no obvious
function (appendix, whale hip bones, snake hip bones, the pink
thing in the corner of our eyes -nictitating membrane)
14. Biochemistry: Dna, enzymes
15. Convergent evolution: similar features in independent
evolutionary lineages
16. Adaptive radiation: one branches off and gives rise to many
different species, to fill different ecological roles in the
community
17. Behavioral isolation: behavior separates the species
18. Divergent evolution: similar species split apart
19. Genetic drift: causes change in allele frequencies, chance
events can cause allele frequencies to fluctuate unpredictably
20.
Gene flow: individuals entering/leaving a population and
can result in changes in allele frequency, helps to reduce the
genetic differences between populations
21. Founder effect: a type of genetic drift; when a few members
of the population are taken to an isolated area and the new
groups genetic composition is not reflective of the original
population (severely limits the gene pool) ; the amish with extra
digits
22. Bottleneck: size of the population is drastically reduced by a
natural disaster or human action; the population is not
genetically representative of the original (cheetahs, bison)
23. Sexual selection: mate chooses its mate; intrasexual
selection is when same sex individuals compete for the opposite
sex; intersexual selection is when the female chooses
24. Directional Selection: phenotype on end of the phenotypic
range survive (are selected for)
25. Disruptive selection: individuals on both extremes survive
and reproduce more successfully than those with intermediate
phenotypes
26. Stabilizing selection: intermediate phenotypes survive and
reproduce more successfully than the extreme phenotypes
27. What does it mean to be in hardy weinberg equilibrium?
Population is not evolving
28. What could it mean if a population is not in hardy Weinberg
equilibrium? We are evolving possibly due to mutations, natural
selection, smaller population, nonrandom mating, gene flow
29. What is it called when similar features develop from
unrelated groups because of the environment? (analogous
structures would be an example) convergent evolution
30. What 2 things does a chi square compare? Compare
expected and observed ratios of two qualitative traits
31.
Why would we use a chi square? to determine correlations
between “phenotypic” characteristics
32. In a species of mice the B allele for brown fur is dominant to
the b allele for white fur. In a cross of a brown parent with a
white parent there were 176 total births. 106 were brown, 70
were white.
The null hypothesis is that the brown parent was heterozygous.
(Bb for the dominant)
∑(e-o)2/e (for each individual group)
What is the chi square statistic? What is the p value and what
does it mean? Bb x bb
B
b
b
Bb
bb
b
Bb
bb
We expect 50% brown/50%white (expecting 88 to be brown/88
to be white
Our observed: 106 brown/70 white
Brown (o-e)2 /e (88-106)2 / 88 = 3.68
White
(70-88)2 /88 = 3.68
X2 statistic is 3.68 + 3.68 = 7.36
Degrees of freedom (n-1) we have 2-1= 1 degree of freedom
P value < .01 showing there IS a significant difference to what we
expected
33. If a population is in hardy Weinberg equilibrium: The
frequency of an allele that causes red eyes in drosophilia is .45.
While the frequency of the alternate allele for sepia eyes is .55.
Red eyes are dominant to sepia eyes.
What is the frequency of individuals with red eyes?
P2 + 2pq + q2 = 1
P= .45
Q = .55
P2= .2025 (homozygous dominant trait)
2pq= .495 (heterozygous)
Q2 = .3025 (homozygous recessive trait)
If there were 1100 individuals in the population, how many
would be sepia? 1100 x .3025= 332.75 people
34. What is sexual dimorphism and why does it matter?
Marked differences between the secondary sex characteristics
between males and females; sexual selection: different traits
are more appealing; sign of fitness based on “flash” for males;
more masculine features imply strength; females are usually
more “drab” to allow for safety which would aid in survival to
care for
34. What kinds of characteristics of a population help increase
the potential for evolutionary change? Variation in the
population, large population size, gene flow, random mating,
natural selection
35. What is catastrophism? What does this have to do with
evolution? Catastrophes occur suddenly caused by different
mechanisms; could make species go extinct or certain alleles to
be taken out (Cuvier theorized this but he was against evolution)
36. What is punctuated equilibrium? How does this relate?
In the fossil record long periods of stasis in which a species
undergoes little or no morphological change and then is
interrupted by brief periods of sudden change.
37. What are derived traits? Ancestral traits? Derived trait has
no ancestral link it is a new trait; ancestral traits are inherited
38. What is reproductive isolation? The existence of biological
barriers that keep members of two species from producing
viable, fertile offspring. Prezygotic/postzygotic
39. What is geographic isolation? Isolated because of a
geographic barrier
40. What is a mutation?
Change in the genetics of an individual (can possibly make new
species
41. What is thought to be the initial cause of so many types of
darwin’s finches? Originally came from South America (flew or
rafted over), then sympatric speciation occurred.