Unit 6 Flashcards
1
Q
Fossils
A
Old remains that provide evidence of evolution and history of life on earth
2
Q
Lamarck
A
Lamarck believed that if you acquired a trait in your life your offspring would also acquire it
3
Q
Natural selection
A
Natural selection is the process When organisms have traits that better suit the environment are more likely to survive and over time it leads to the adaptation of a population
4
Q
Natural selection
A
Natural selection is the process When organisms have traits that better suit the environment are more likely to survive and over time it leads to the adaptation of a population
5
Q
Artificial Selection
A
Artificial selection is the intentional breeding done to pick the offsprings traits EXAMPLE: DOGS
6
Q
Homologous structures
A
Features in different species that have a common ancestor and different functions EXAMPLE: Forearm structure of humans bats whales
7
Q
Vestigial Structures
A
Features that have lost there original function through evolution EXAMPLE: Human Appendix
8
Q
Analogous structures
A
Features in different species that have similar functions but no common ancestor EXAMPLE: Birds wings and insects wings
9
Q
Convergent evolution
A
Unrelated organisms evolve similar traits due to environment
10
Q
Pangea
A
Pangea was a supercontinent that formed 250 million years ago then broke off creating continents we know today
11
Q
Endemic Species
A
Organisms that are native to a specific area that are found no where else but there
12
Q
Phylogeny
A
A family tree of how different species are related and have evolved over time
13
Q
Phylogenetic Trees
A
A chart that looks like a tree showing how species are connected
14
Q
Shared Ancestral Character
A
A trait that Ancestors had and all of descendants still have
15
Q
Outgroup
A
A comparison point in a family tree to find out what traits are old vs new
16
Q
Molecular Clock
A
A way to estimate how long ago species split apart by looking at dna change
17
Q
Micro evolution
A
Small changes in a populations traits ovetime
18
Q
Genetic Variation
A
Differences in dna among individuals in a population
19
Q
Population
A
A group of the same species living in the same area
20
Q
Gene pool
A
All the genes and their different versions (alleles) in a population. It’s like a “pool” of genetic options.
21
Q
Hardy-Weinberg Equilibrium
A
Where a populations genes don’t change over time only if very specific conditions are met
22
Q
5 Conditions Necessary for Hardy-Weinberg Equilibrium
A
- No mutations (no changes in DNA).
- Random mating (no picking specific partners).
- No natural selection (all traits are equally good).
- Extremely large population size (to avoid random changes).
- No gene flow (no moving in or out of the population).
23
Q
Genetic Drift
A
Random changes in a population’s gene pool, especially in small populations.
24
Q
Founder effect
A
When a small group breaks off from a larger population and starts a new one, their genes shape the new population.
25
Bottleneck Effect
When a population shrinks a lot because of a natural disaster and the gene pool shrinks
26
Bottleneck Effect
When a population shrinks a lot because of a natural disaster and the gene pool shrinks
27
Gene flow
When genes move between populations when an animal breeds with a different heard or group
28
Fitness
How well an organism can survive and reproduce compared to others in its population.
29
Directional Selection
When natural selection favors one extreme trait, like giraffes with longer necks.
30
Disruptive Selection
When natural selection favors both extreme traits but not the average, like birds with either very small or very large beaks.
31
Stabilizing Selection
When natural selection favors the average trait and gets rid of the extremes, like medium-sized babies surviving better than very small or very large ones.
32
Heterozygote Advantage
When individuals with two different versions of a gene (heterozygotes) have a survival advantage, like people with one sickle-cell gene being protected from malaria.
33
Sexual Selection
When certain traits make an individual more likely to mate, like bright feathers on a peacock attracting mates.
34
Macroevolution
Big changes in life over a long time, like the evolution of new species or groups, such as dinosaurs turning into birds.
35
Biological Species
A group of organisms that can mate and have fertile babies If they can’t, they are considered different species.
36
Biological Species
A group of organisms that can mate and would choose to mate and have fertile babies If they can’t, they are considered different species.
37
Reproductive Isolation
When different groups of the same species can’t mate and produce fertile offspring anymore, leading to the creation of new species.
38
Allopatric Speciation
When new species form because a population gets split by a physical barrier, like a river or mountain.
39
Geographic Isolation
When groups of a species are separated by geography (like oceans or mountains), so they can’t breed with each other.
40
Geographic isolation vs allopatric speciation
Geographic separates same population preventing them from mating
Allopatric is new species forming from geographic isolation
41
Sympatric Speciation
When new species form without physical barriers, like through genetic changes or different behaviors.
42
Sexual Selection (Behavioral Isolation)
When animals pick mates based on specific behaviors, like a bird’s song or a dance. If groups prefer different behaviors, they stop mating with each other.
43
Polyploidy (Reproductive Isolation)
When a mistake in cell division gives a plant or animal extra sets of chromosomes, making it unable to mate with the original group.
44
Temporal Isolation
When groups can’t mate because they breed at different times, like one group breeding in spring and another in fall.
45
Radiometric Dating
A way to find the age of rocks or fossils by measuring the decay of radioactive elements, like carbon or uranium.
46
Half-Life
The time it takes for half of a radioactive substance to decay. Scientists use this to figure out how old things are.
47
Pangea
A supercontinent that existed a long time ago, where all of Earth’s land was joined together before splitting into today’s continents.
48
Mass Extinctions
Events when a huge number of species die out in a short time, like when the dinosaurs went extinct.
49
Homeotic Genes & Embryonic Development
Homeotic genes are like “master switches” that control how body parts form during the development of an embryo. Changes in these genes can lead to major evolutionary changes.
50
Ways sexually reproducing organisms increase genetic diversity without mutations
1. Independent assortment: Chromosomes randomly separate during meiosis, creating unique gametes.
2. Crossing over: Homologous chromosomes exchange DNA during meiosis.
3. Random fertilization: Any sperm can fertilize any egg, leading to numerous genetic combinations.
51
How new alleles are created in a population
New alleles arise through mutations, which are changes in the DNA sequence. These mutations can be caused by errors during DNA replication or by environmental factors like radiation or chemicals.
52
What determines if an allele is harmful or helpful?
The environment determines if an allele is harmful, neutral, or helpful.
• Helpful alleles increase an organism’s chances of survival and reproduction (e.g., thicker fur in cold climates).
• Harmful alleles decrease fitness (e.g., a mutation causing a deadly disease).
This process works through natural selection, where helpful alleles become more common over time.
53
Hardy-Weinberg Equation and Variables
The equation:
p² + 2pq + q² = 1
Definitions:
1. p² = The frequency of homozygous dominant individuals (e.g., TT).
2. q² = The frequency of homozygous recessive individuals (e.g., tt).
3. 2pq = The frequency of heterozygous individuals (e.g., Tt).
4. p = The frequency of the dominant allele (T).
5. q = The frequency of the recessive allele (t).
54
Conditions for Hardy-Weinberg Equilibrium
1. No mutations.
2. Random mating.
3. No natural selection.
4. Large population size (no genetic drift).
5. No migration (no gene flow).
55
Genetic Drift vs. Gene Flow
• Genetic drift: Random changes in allele frequencies, especially in small populations. Example: A storm kills random individuals regardless of their traits.
• Gene flow: Movement of alleles between populations through migration. Example: Wolves from one pack breeding with another.
Difference: Genetic drift is random; gene flow involves migration between populations.
56
Example of decreased genetic variation
Bottleneck effect: When a disaster drastically reduces population size, like hunting reducing cheetah numbers, leaving fewer alleles in the gene pool.
57
Why does natural selection happen faster in small populations?
Small populations are more affected by genetic drift and inbreeding, which can make harmful alleles disappear and beneficial ones spread faster. Populations become small due to events like habitat destruction or disasters.
58
Why would a lethal allele like sickle-cell anemia be more persistent in the human population of a country near the equator?
The sickle-cell allele is more persistent because being heterozygous offers protection against malaria, a common disease near the equator.
59
A population undergoes a sharp reduction due to a disease wiping many individuals out – this would create what? Why could this be dangerous?
wiping out many individuals would create a bottleneck effect, which is dangerous because it reduces genetic diversity and increases the risk of inbreeding.
60
How would the gene pool of a small island compare with the gene pool of a large continent
A small island would have less genetic diversity due to smaller populations and isolation
61
Would a large or small continent undergo genetic drift faster
The small island would because it’s small population makes random changes in allele frequencies more common
62
Four population mechanisms that lead to evolutionary change
Natural selection
Genetic drift
Gene flow
Mutations
63
Lamarck evolution belief why was he wrong
Lamarck thought that when a organism acquired a trait or skill in its life time then the offspring would also acquire this when born
64
Where did Darwin collect research for evolution
Galápagos Islands
65
Why did Darwin believe evolution was happening
He found glyptodonts fossils they looked like armadillos he then got interested and started to research
66
Darwin’s birds
He discovered that the finches on each island had diffrent beak sizes and various other differences
67
Darwin’s birds
He discovered that the finches on each island had diffrent beak sizes and various other differences
68
Darwin dog breeding
Dog breeding helped him understand natural selection because humans could choose certain traits they wanted then so could the environment
69
Describe natural selection
Variation
* genetic diversity
Overproduction
*surplus in offspring
Adaption
*passing on the better traits
Decent with modification
*gradual changes and evolution
70
Directional Selection
Favors one extreme phenotype, shifting traits in one direction
71
Disruptive Selection
Favors extreme phenotypes at both ends, selecting against intermediates
72
Stabilizing Selection
Favors intermediate phenotypes, reducing extremes
73
Ways to determine if two organisms are the same species
Can produce fertile offspring
Chromosome number
Would they choose to breed
74
What is speciation
Speciation is the process by which one species splits into two or more distinct species. It occurs when populations become reproductively isolated through mechanisms such as
Sympatric behavioral temporal
Allopatric geographic
75
Sympatric speciation
Behavioral isolation
Temporal isolation
76
Allopatric
Geographical isolation
77
Geographic isolation
Physical barriers separate populations
Allopatric speciation
78
Behavioral isolation
Diffrent behaviors based on instincts
Sympatric speciation
79
Temporal isolation
Same population choose to mate at different times of year
Sympatric speciation
80
Name two pre-zygotic barriers to mating and explain how each works.
Temporal isolation only breed certain times
Behavioral isolation only will breed with certain organisms
81
How do fossils form
An organism dies and sediment and minerals replace bone causing it to fossilize
82
Hox genes
Vertieberys
83
Dlx
Limb genes
84
Four features of common ancestory among all living organisms
DNA
Cells
Cell membrane
Reproduction or dna copying
