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Biology 1306 > Chapters 22-27 > Flashcards

Chapters 22-27 Flashcards

1
Q

Evolution

A

Descent with modification; a change in the genetic composition of a population from generation to generation

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2
Q

Descent with modification

A

Earth’s many species are descendants of ancestral species that were different from the present-day species

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3
Q

Fossils

A

The remains or traces of organisms from the past

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4
Q

Strata

A

Superimposed layers of rocks that fossils lie within

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5
Q

Paleontology

A

The study of fossils

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6
Q

Adaptations

A

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments

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7
Q

Natural selection

A

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than those that don’t

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8
Q

Artificial selection

A

Selecting and breeding individuals that possess desired traits

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9
Q

Homology

A

Similarity resulting from shared ancestry; not necessarily similar function

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10
Q

Homologous structures

A

Structures that represent variations on a structural theme that was present in a common ancestor

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11
Q

Vestigial structures

A

Remnants of features that served a function in the organism’s ancestors

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12
Q

Evolutionary tree

A

A diagram that reflects evolutionary relationships among groups of organisms

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13
Q

Convergent evolution

A

The independent evolution of similar features in different lineages

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14
Q

Analogous

A

Share similar feature because of convergent evolution; features share similar function, but not common ancestry

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15
Q

Biogeography

A

The scientific study of the geographic distributions of species

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16
Q

Pangaea

A

The single large continent 250 million years ago

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17
Q

Endemic

A

Found no where else in the world

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18
Q

Microevolution

A

A change in allele frequencies in a population over generations

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19
Q

Genetic variation

A

Differences among individuals in the composition of their genes or other DNA sequences

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20
Q

Neutral variation

A

Differences in DNA sequence that do not confer a selective advantage or disadvantage

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21
Q

Mutation

A

A change in the nucleotide sequence of an organism’s DNA

22
Q

A point mutation

A

The change in as little as one base in a gene; can have significant impact on phenotype

23
Q

Gene variability

A

Genetic variation at the whole gene level

24
Q

Nucleotide variability

A

Genetic variation at the molecular level of DNA

25
Introns
Non-coding segments of DNA
26
Exons
The regions retained in mRNA after RNA processing
27
Population
A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
28
Gene pool
All copies of every type of allele at every locus in all members of the population
29
Locus
A specific place along the length of the chromosome where a given gene is located
30
Hardy-Weinberg Equilibrium
In a population that is not evolving, allele and genotype frequencies will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles is at work
31
5 conditions of Hardy Weinberg Equilibrium
1. No mutations 2. Random mating 3. No natural selection 4. Extremely large population size 5. No gene flow
32
Adaptive evolution
A process in which traits that enhance survival or reproduction tend to increase in frequency over time
33
Genetic drift
Chance events that can also cause allele frequencies to fluctuate unpredictably from one generation to the next, especially in small populations
34
Founder effect
When a few individuals become isolated from a larger population and this smaller group establishes a new population whose gene pool differs from the source population
35
Bottleneck effect
A sudden change in the environment that drastically reduces the size of a population (ex. Flood, fire)
36
Summary of the effects of genetic drift
1. Genetic drift is significant in small populations 2. Genetic drift can cause the allele frequencies to change at random 3. Genetic drift can lead to a loss of genetic variation within populations 4. Genetic drift can cause harmful alleles to become fixed
37
Gene flow
The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes
38
Relative fitness
The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
39
Directional selection
When conditions favor individuals exhibiting one extreme of a phenotypic range
40
Disruptive selection
Occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes
41
Stabilizing selection
Acts against both of the extreme phenotypes and favors intermediate variants
42
Sexual selection
A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates
43
Sexual dimorphism
A difference in secondary sexual characteristics between males and females of the same species
44
Intrasexual selection
Selection within the same sex; individuals of one sex compete directly for mates of the opposite sex
45
Intersexual selection
Mate choice; individuals of one sex are choosy in selecting their mates from the other sex; choice usually depends on the showiness of appearance or behavior
46
Balancing selection
Includes frequency dependent selection and heterozygote advantage
47
Frequency Dependent selection
Fitness of a phenotype depends on how common it is in the population
48
Heterozygote advantage
When individuals who are heterozygous at a particular locus have greater fitness than do both kinds of homozygotes
49
Pseudogene
A DNA segment that is very similar to a real gene but does not yield a functional product; a DNA segment that formerly functioned as a gene but has become inactivated in a particular species because of mutation
50
3 mechanisms of evolution
1. Natural selection 2. Genetic drift 3. Gene flow
51
Phenotype
The product of an inherited genotype and many environmental influences

Biology 1306 (1 decks)

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