Chapter 14 - Evolution And Natural Selection

Front 1

Evolution

Back 1

- Genetic change in a population of organisms over time (generations)

- Darwin proposed that natural selection was the mechanism of evolution

Front 2

Adaptation

Back 2

Any peculiarity of structure, physiology or behavior that promotes the likelihood of an organism's survival and reproduction in a particular environment

Front 3

Variation

Back 3

- Enters a population through mutation

- Without variation, a population cannot evolve

- Selection, artificial or natural, can only work on variation that exists in a population

Front 4

Fossil

Back 4

- The preserved remains, tracks, or traces of once-living organisms

- Created when organisms become buried in sediment

- Most fossils are skeletons

- Contains the most direct evidence of evolution

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Sedimentary Rock

Back 5

- Organisms are fossilized when they are buried in sediment

- We don't have fossil remains of many organisms because they were never buried in sediment

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Molecular Clock

Back 6

A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules

Front 7

Vertebrate

Back 7

- A backbone made of bony segments called vertebrate (found in animals)

- All vertebrate embryos, including humans, have pharyngeal pouches (these develop into gill slits in fish) and a rudimentary tail (in humans all that remains of this tail is the coccyx

- Similar bone structure is seen in different species of vertebrates

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Embryo

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- Formed by the division of the fertilized egg

- All vertebrates have similar embryos, indicating that the instructions for early development are critical and have not evolved major differences

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Homologous Structure

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- A human arm and a bat wing are “homologous”

- Have different functions but similar structures as a result of descending from a common ancestor

- Homology due to descent from a common ancestor is the result of “divergent” evolution

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Analogous Structure

Back 10

- Similar structures due to parallel evolution

- When organisms evolve in the same environment, they may evolve structures that have similar functions

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Vestigial Organ

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- Organs that are genetically determined, but have lost much of their ancestral function in a given species, but have nonetheless retained those processes through evolution

- Examples include the human appendix and the pelvis of a whale

Front 12

Convergent Evolution

Back 12

- Parallel evolutionary adaptations to similar environments

- Results in analogous structures

Front 13

Mutation

Back 13

- A permanent change in the dna of an organism

- Occurs in DNA

- Will lead to alterations in a protein

Front 14

Migration

Back 14

The movements of individuals or alleles into or out of a population

Front 15

Allele Frequency

Back 15

Refers to how many people in a population carry a particular allele

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Genetic Drift

Back 16

- Random loss of alleles which can cause drastic changes in a small population

- If only a few members of the population carry certain alleles, and they die or are lost or fail to reproduce, then these alleles are lost from the population

Front 17

Founder Effect

Back 17

Occurs when a few individuals leave one population and become the foundation of a new population

Front 18

Nonrandom Mating

Back 18

- Individuals mate with each other preferentially in a nonrandom way

- Occurs in populations where, either by choice or geographic isolation, there is little mating outside the population

- Can cause an unusually high allele frequency for specific alleles in a population

Front 19

Natural Selection

Back 19

A natural process whereby the conditions in the environment determine which organisms survive and reproduce

Front 20

Artificial Selection

Back 20

Intentional selection of breeding partners based on desired characteristics

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Species

Back 21

A group of organisms that can breed successfully in nature and produce fertile offspring

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Population

Back 22

- Consists of all the organisms in an area that are of the same species

- In a population, more individuals are produced than can survive

- Members of a population compete for limited resources

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Isolating Mechanism

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- Make it difficult/impossible for organisms of same species to breed

- Over time (with unique processes of natural selection occurring in different groups) this leads to speciation

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Speciation

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- Involves successive change: first, local populations become increasingly specialized

- If they become different enough, natural selection may act to keep them that way

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Reproductive Isolation

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- Populations whose members do not mate with each other or who cannot produce fertile offspring

- Belong to different species

Front 26

Prezygotic Isolating Mechanism

Back 26

Mechanisms that prevent the formation of a zygote (fertilized egg)

Front 27

Geographic Isolation

Back 27

Members of a species are physically separated and cannot breed

Front 28

Ecological Isolation

Back 28

Members of a species in an area are localized to a particular part of the habitat, and so do not breed

Front 29

Behavioral Isolation

Back 29

Courtship and mating rituals may differ and prevent breeding

Front 30

Temporal Isolation

Back 30

Different breeding seasons prevent breeding

Front 31

Mechanical Isolation

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Structural differences between organisms prevent them from breeding

Front 32

Sickle-Cell Anemia

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- Hereditary disease

- The sickle cell allele causes abnormal red blood cells

- Homozygous for the sickle cell allele – usually die

- Heterozygous – make enough normal red blood cells (normal hemoglobin) to function

- Very common in parts of Africa

Front 33

Stabilizing Selection

Back 33

Selects the heterozygote advantage (heterozygotes are resistant to malaria)

Front 34

Disruptive Selection

Back 34

- Acts to eliminate the intermediate phenotype

- The intermediate phenotype is less able to survive

Front 35

Directional Selection

Back 35

- Acts to eliminate one extreme

- Genes for this extreme become less available... phenotypic range shifts

Front 36

What type of evolution is a MAJOR EPISODE OF EXTINCTION?

Back 36

Macroevolution

Front 37

What type of evolution is THE APPEARANCE OF A NEW SPECIES?

Back 37

Macroevolution

Front 38

What type of evolution is NATURAL SELECTION RESULTING IN ALLELE FREQUENCY CHANGE IN POPULATION?

Back 38

Microevolution

Front 39

What is a trait that gives an organism a survival advantage over other organisms?

Back 39

Adaptation

Front 40

How do most adaptations arise?

Back 40

As random, spontaneous mutations

Front 41

How does the theory of punctuated equilibrium differ from the theory of gradualism when considering the pace of evolution?

Back 41

Punctuated equilibrium proposes that evolutionary events occur in spurts, while gradualism proposes that evolution is a gradual, ongoing process

Front 42

Which theory includes the idea that there may be long periods of time without evolution?

Back 42

Punctuated equilibrium

Front 43

What are the preserved remains of dead organisms called?

Back 43

Fossils

Front 44

Fossils are created when an organism becomes buried in .....

Back 44

Sediment

Front 45

Which layer of rock is the oldest in sedimentary rock?

Back 45

The bottom layer

Front 46

How does sedimentary rock allow the dating of fossils?

Back 46

Determines the age of the rock

Front 47

What is a molecular clock?

Back 47

A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules

Front 48

In a molecular clock, will organisms that are closely related have A FEW or MANY AMINO ACID DIFFERENCES in their proteins?

Back 48

Few

Front 49

Did organisms that are closely related diverge RECENTLY or DISTANTLY?

Back 49

Recently

Front 50

What types of structures are similar in structure but not in function?

Back 50

Homologous

Front 51

What types of structures are similar in function but not in structure?

Back 51

Analogous

Front 52

What types of structures are a result of covergent evolution?

Back 52

Analogous

Front 53

What term describes organs that are remnants of a useful organ in a previous ancestor?

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Vestigial

Front 54

The wing of a bat and the arm of a human are ______________.

Back 54

Homologous

Front 55

The flippers of penguins and dolphins are ______________.

Back 55

Analogous

Front 56

The human appendix is an example of a ____________________.

Back 56

Vestigial organ

Front 57

What is the definition of a mutation? Does a mutation occur in DNA or in proteins?

Back 57

A permanent change in the DNA of an organism; a mutation occurs in DNA, but will lead to alterations in a protein

Front 58

List 4 mechanisms that can cause a change in the allele frequency of a population

Back 58

- Migration

- Genetic drift

- Nonrandom mating

- Selection

Front 59

The movement of individuals into or out of a population is called _____________

Back 59

Migration

Front 60

List and describe two types of genetic drift

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- Founder effect occurs when a few individuals leave a population and become the foundation for a new population

- Bottleneck effect occurs when many individuals in a population die and a few individuals survive to form the basis of the next generation

Front 61

The amish community marries preferentially within their own community, limiting their gene pool and increasing the allele frequencies of several negative traits. This behavior is called ________________

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Nonrandom mating

Front 62

How does artificial selection differ from natural selection? Which type of selection has had the greatest influence on evolution?

Back 62

- Artificial selection occurs when organisms are intentionally chosen for breeding because of their traits; in natural selection organisms with advantageous traits are not chosen, but have a better chance to survive and therefore to reproduce.

- Natural selection