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Human Bio Exam 1 Review > Topic 1 Evolution > Flashcards

Topic 1 Evolution Flashcards

1
Q

Who proposed Kin selection theory?

A

Hamilton, 1963

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2
Q

What is kin selection theory

A

We are more likely to save family than non-relatives to preserve genes thru close relatives

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3
Q

What is the difference between sexual selection and natural selection?

A

Sexual selection is not about a struggle for survival, but for mating opportunities
(Darwin, 1871)

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4
Q

What is sexual selection in short?

A

“male competition; female choice”

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5
Q

What are the mechanisms of sexual selection?

A

Contests, mate choice, scrambles, sexual coercion, sperm competition

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6
Q

What is contests in sexual selection?

A

Basically fight for mates

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7
Q

What is mate choice in sexual selection?

A

Preference or other traits that increase the odds of copulation and/or conception with mates having particular characteristics

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8
Q

What is scrambles in sexual selection?

A

Competition to find fertile mates

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9
Q

What is sexual coercion in sexual selection?

A

Using force or threat against a potential mate to increase chance of copulating with a mate or lower their chances of copulating with a competitor

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10
Q

What’s sperm competition in sexual selection?

A

Competition within a single female between the sperm of multiple males

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11
Q

What were the three out of four selections that Darwin could explain? Why can’t he explain the fourth?

A

He can explain natural, artificial, and sexual

However he cannot explain kin selection due to a lack of genetics understanding (you share your genes)

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12
Q

Is mating within a population almost never random?

A

Yes, because it is a massive factor in evolution since that’s how it proceeds

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13
Q

What is a gene pool?

A

The sum of genes in a population

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14
Q

What can be used to look at proportions of alleles in a population?

A

Hardy Weinberg

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15
Q

How would evolution have occurred based on Hardy Weinberg?

A

If the frequencies changed from one generation to another, then EVOLUTION HAS OCCURRED

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16
Q

Is evolution a change in allele frequencies of a population over time?

A

Yes, evolution is the change of allele frequency over time

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17
Q

What conditions would cause allele frequencies to NOT change?

A

Very large population; prevents genetic drift
No migration; prevents gene flow
No mutation; no genetic variance/change
Random mating; prevents sexual selection
Everyone is equally fit; no natural selection

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18
Q

What are the three big evolutionary causes in a population?

A

Mutation, natural selection, and non-random mating

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19
Q

What are the additional two causes of evolution?

A

Gene flow and genetic drift

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20
Q

What is gene flow?

A

Migration; immigration of new individuals with new/different alleles

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21
Q

What population size is drastically affected by chance?

A

Small populations are more vulnerable to genetic drift

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22
Q

What is genetic drift?

A

Chance occurrences, and in the form of population bottleneck and founder effect

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23
Q

What is the bottleneck effect?

A

A parent population gets drastically reduced (by disaster for example) and the surviving individuals represent a new allele frequency that may not be the same as the parent population in the new generation

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24
Q

What percentage range of most species have heterozygous loci?

A

20-40% of most species have heterozygous loci

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25
What are some examples of bottleneck effects?
Northern elephant seals that got hunted, cheetahs, and both ancient and modern human populations
26
What's the difference in genetic variability between a house cat, inbred cat, and a cheetah?
House cats have the most genetic variability with the most heterozygous loci, while the inbred cat has slightly less variability, and the cheetah is like 93% homozygous in their genome.
27
What is the difference between bottleneck and founder effect?
Bottleneck usually results from the parent population getting destroyed while the surviving, smaller population goes on. In founder effect, the main population is fine, but a smaller portion of the population finds itself ISOLATED from the main, and thus possibly starts a new population no representative of the parent one due to the isolation
28
When did we disperse out of Africa
About a 100 kya
29
What were the possible reasons for the massive bottleneck of humans about 900 kya?
Possibly a volcano eruption that blanketed the Earth and starved people to death
30
Are Africans or dispersed humans more genetically diverse?
Africans are more genetically diverse than those who dispersed to other parts of the world
31
Why was there a fossil gap back when there was the bottleneck effect for humans 900 kya?
There was simply not much humans to go dying into the ground to make fossils, so less were found in those layers of earth
32
What is a genetic drift example in humans?
The Amish people who have kids that have a higher chance of getting Ellis-van Creveld than the rest of the population This makes the kids get polydactyly, usually for fingers
33
What is Ellis-Van Creveld?
An autosomal recessive disorder with two abnormal genes associated with it (in 4th chromosome) Characterized by dysplasia, dwarfism, polydactyly, and congenital heart diseases (>50%)
34
How were the Amish isolated? Icelanders?
The Amish culturally isolated themselves and bred within their group The Icelanders were geographically isolated Both kept good gene records
35
What is dysplasia in regards to the Ellis-Van Creveld disease?
It's when your cartilage sucks and the ball and socket joint might just turn out to be ball and not much of a socket for the ball
36
What is BRCA and its relation to founder effect?
It's a cancer suppressor that can mutate to become disabled, so cancer can go unchecked. You're more likely to get cancer if this is so, but not guaranteed. Relating to founder, Among the Ashkenazi Jewish peoples, they are significantly more likely to have this BRCA mutation than an average American. Just to note, anyone can get BRCA1/2 mutations Also it's autosomal dominant
37
What is Tay-Sachs and its significance to founder's effect?
Ashkenazi Jews, Cajuns, French Canadians, and Irish Americans are more likely than the average person to get Tay-Sachs The disease is autosomal recessive on the 15th chromosome and is when an enzyme is not made to digest ganglioside GM2 so that stuff builds up in a lysosome and this buildup will eventually kill a cell
38
How could a autosomal dominant gene disease go on?
If it shows up and kills you later in life AFTER you've had kids, then it continues in your genes of your kids
39
What is an example of an autosomal dominant gene disease?
Huntington's disease which usually shows up later in life around and after reproductive periods of a human life, which by then they might have kids which now possibly carry the disease.
40
Who is Nancy Wexler in relation to Huntington's disease?
She studied Venezuelan groups with a higher rate of HD to help learn about it and find a treatment or test (she had it herself)
41
Is sickle cell disease an example of founder effect?
No, not really More like natural selection due to heterozygote advantage of having it and living enough and also being immune to malaria parasites which can't live on sickled blood cells
42
How does sickle cell affect the makeup of a blood cell?
It's a point mutation that causes the cell to toughen up and curl into a sickle shape when exposed to oxygen due to messed up protein structure starting at the primary structure up to the quaternary structure where the function gets affected (less O2 to carry)
43
What kind of effects does sickle cell have?
It's a one nucleotide substitution that has multiple effects, so it's pleiotropic Stuff such as anemia and heart failure due to breakdown of RBC and clumping and clogging
44
What is the heterozygote advantage in regards to sickle cell?
Homozygous dominant (normal): you die of malaria Homozygous recessive: die of sickle cell (which is beyond survivable levels) Heterozygous: you survive both malaria (can't survive on sickle cells) and sickle cell (not severe enough to be fatal)
45
Summarize causes of evolution
Mutation: create new alleles; increase variability Gene flow: increase similarity of different populations Genetic drift: cause random change of allele frequency; can eliminate alleles too Nonrandom mating: change genotype frequencies (sexual selection) Selection: increases frequency of favored alleles; can produce adaptations
46
What are the three ways that selection can influence populations?
Directional, stabilizing, and disruptive selection of population
47
What is directional selection?
Shifting a population towards a favored trait
48
What is stabilizing selection?
The extremes are disfavored and the stable mean is favored (less variability)
49
What is disruptive selection?
The extreme on either end is favored, and the mean average gets disfavored. Could lead to speciation if the extremes end up varying enough
50
What is a example of a polygenic trait?
Height Skin color; this one has at least 378 gene loci to determine color
51
When is directional selection most common?
It's most common in unstable environments
52
What is an example of directional selection?
Anthropogenic (human caused) industrial melanism in peppered moths
53
What is a human example of recent evolution
The Netherland people, Dutch, are the tallest in the world on average in the past 150 years. Most likely due to their egalitarian systems and overall better lifestyles that can support the growth. Taller men were selected for, and medium sized women were favored (because of birth complications favoring average woman; too big or small of a woman can be a problem for birth).
54
What is an example of stabilizing selection?
Stabilizing selection acts against individuals deviating too far from the average. This is seen in birth weight, where too small is underdeveloped, and overweight is problematic in delivery and possibly development as well. For the big baby thing, it's possible that the baby gets affected by gestational diabetes that develops in the mom, so it gets a bunch of glucose that it has to get rid of. The mom's insulin isn't passed on, so the baby produces more insulin. Insulin acts as a growth factor to make the baby physically bigger, and this cuts into the development of actual organs. Thus they are not likely to survive as much as a average baby weight.
55
What is an example of disruptive selection?
Butterflies getting different patterns to mimic certain not-so-good tasting species while the mean or average butterfly cannot mimic and thus gets eaten. This could cause speciation if there's enough genetic variation
56
How do new species form?
2 major requirements for speciation are ISOLATION and TIME The most important part is REPRODUCTIVE ISOLATION
57
What are the two major modes of speciation?
Allopatric and sympatric speciation
58
What is allopatric speciation?
Speciation taking place in populations with geographically separate ranges where gene flow is disrupted. This is physical separation of populations
59
What is sympatric speciation?
speciation that takes place in geographically overlapping populations. Chromosomal changes and nonrandom mating reduces gene flow
60
What exactly is reproductive isolation?
It means that the male and female individuals cannot produce VIABLE, FERTILE offspring
61
What is the biological species concept (BSC)?
It is exactly what reproductive isolation describes, where individuals can interbreed and produce VIABLE, FERTILE offspring. This describes how "fit" an individual is due to passing on their genes.
62
What is the difference in the chromosome count in humans vs other primates?
We have 46, they have 48.
63
Why do we have 46 chromosomes and not 48 like other primates?
Our second chromosome fused
64
When did the chromosome fusion happen?
Around when there was the massive bottleneck in humans, so about 900-700 kya
65
How is reproductive isolation employed via biological mechanisms?
Prezygotic barriers like habitat isolation, behavioral isolation, mechanical isolation, or gametic isolation Postzygotic barriers like reduced hybrid viability, fertility, and breakdown

Human Bio Exam 1 Review (3 decks)

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