Biology Exam 2 Review

Front 1

What are species?

Back 1

Groups of organisms that interbreed and share a suite of genetic and morphological attributes, and are reproductively isolated from other such groups.

Front 2

What is speciation?

Back 2

The divergence of biological lineages and the emergence of reproductive isolation between lineages, creating separate species.

Front 3

What are the three major classes of species concepts?

Back 3

Morphological, biological, and lineage.

Front 4

What does the morphological species concept state?

Back 4

A species comprises individuals that look alike and that individuals that do not look alike belong to different species.

Front 5

Why does the morphological species concept work?

Back 5

Members of the same species share alleles that code for the same morphological features.

Front 6

What are the two limitations of the morphological species concept?

Back 6

1. Members of the same species do not always look alike, like the males, females, and young individuals.

2. Cryptic species, which look exactly the same and indistinguishable, do not interbreed.

Front 7

What does the biological species concept state?

Back 7

Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.

Front 8

What is reproductive isolation?

Back 8

A state in which two species can no longer exchange genes.

Front 9

What are the three limitations of the biological species concept?

Back 9

1. Does not work with closely related individuals.

2. Does not apply to organisms that reproduce asexually.

3. Limited to a single point in evolutionary time.

Front 10

What does the lineage species concept state?

Back 10

Species split into two descendant species which thereafter evolve as distinct individuals and are considered over evolutionary time.

Front 11

What is a lineage?

Back 11

An ancestor-descendant series of populations over time.

Front 12

What is the most important idea for the origin of species?

Back 12

Reproductive isolation

Front 13

What is the Dobzhonsky-Muller Model?

Back 13

A mode that explains how reproductive isolation results from accumulation of genetic incompatibilities following a splitting of an ancestral population, interrupting gene flow.

Front 14

By the Dobzhonsky-Muller Model, what would happen to the offspring of the two genetically incompatible individuals (looking at alleles)?

Back 14

The hybrid offsprings alleles would be either functionally inferior or lethal causing death.

Front 15

T/F:

Greater geneteic differences and incompatibilities lead to increased reproductive isolation, and thus speciation.

Back 15

True

Front 16

What is allopatric speciation?

Back 16

Speciation resulting when a population is divided by a physical barrier.

Front 17

What is the dominant and most common mode of speciation?

Back 17

Allopatric speciation

Front 18

Whta is sympatric speciation?

Back 18

Speciation without a physical barrier causing reproductive isolation.

Front 19

Whate are the two ways sympatric speciation occurs?

Back 19

1. Disruptive Selection where individuals have preference for distinct microhabitats where mating takes place.

2. Polyploidy where there is a duplication of sets of chromosomes.

Front 20

What is the most common way sympatric speciation occurs?

Back 20

Polyploidy

Front 21

What is autoploidy?

Back 21

Chromosome duplication in a single species, so internal.

Front 22

What is alloploidy?

Back 22

Chromosomes combining from two species, so external kinda.

Front 23

How does autoploidy occur accidentally?

Back 23

If two diploid genes combine, resulting in a tetraploid individual. When the tetraploid and diploid mate, a triploid is made that is sterile. Therefore, tetraploid can only self-fertilize or mate with another teraploid.

Front 24

Why is polyploidy important in plant evolution?

Back 24

70% of flowering species and 95% of fern species are the result of polyploidization because many plants can self-fertilize.

Front 25

What are reinforcement mechanisms?

Back 25

If hybrids are less fit than non hybrids, selection will favor parents that do not produce hybrid offspring. This reinforcement prevents hybridization.

Front 26

What are prezygotic isolating mechanisms?

Back 26

Mechanisms that prevent hybridization from occuring before fertilization.

Front 27

What are postzygotic isolating mechanisms?

Back 27

Mechanisms that reduce fitness of hybrid offspring, selecting against hybrizization.

Front 28

What are the five prezygotic isolating mechanisms?

Back 28

1. Mechanical

2. Behavioral

3. Gametic

4. Temporal

5. Habitat

Front 29

What is mechanical isolation an what is an example?

Back 29

Isolation caused by differences in size and shape of reproductive organs that make mating impossible. For example, orchids pollinators.

Front 30

What is temporal isolation and what is an example?

Back 30

Isolation where mating periods do not develop because the species have different mating seasons. For example, 3 closely related frogs that live in the same habitat breed at different times of year.

Front 31

What is behavioral isolation and what is an example?

Back 31

Isolation due to the fact that individuals reject or fail to recognize potential mating partners. For example, breeding calls of male frogs quickly diverge between related species, so the female frogs ignore calls from other species.

Front 32

What is habitat isolation?

Back 32

Isolation where when two closely related species evolve preferences for living or mating in different habitats, causing them to never come into contact during mating periods.

Front 33

What is gametic isolation?

Back 33

isolation where th eggs of one species do not have appropriate chemical signals for sperm of another species; or sperm is not able to attach to and penetrate the egg.

Front 34

What are the 3 postzygotic isolating mechanisms?

Back 34

1. Low hybrid zygote viability where hybrid zygotes fail to mature normally or have severe abnormalities causing death.

2. Low hybrid adult viability where hybrid offspring may have lower survivorship than nonhybrids.

3. Hybrid infertility where hybrids may mature into infertile adults.

Front 35

What are hybrid zones?

Back 35

When, unless reproductive isolation is complete, closely related species may hybridize in areas where their ranges overlap.

Front 36

What are the 4 factors that can influence rates of speciation across groups?

Back 36

1. Diet specialization

2. Pollination

3. Sexual selection

4. Dispersal ability

Front 37

What is diet specialization and what is an example?

Back 37

When populations with specialized diets are more likely to diverge. For example, herbivorous bugs specialize on one or a few plant species.

Front 38

T/F:

Herbivorous beetle groups contain many more species than the related predatory species do.

Back 38

True

Front 39

What does pollination do for speciation?

Back 39

Speciation rates are higher in animal-pollinated than wind-pollinated plants.

Front 40

What does sexual selection do for speciation and what is an example?

Back 40

The mechanisms of sexual selection result in high rates of speciation. For example, the birds of paradise in New guinea.

Front 41

How does dispersal ability affect speciation and what is an example?

Back 41

Speciation rates are likely to be faster in species with poor disperal abilities because they can be separated by even narrow barriers. For example, land snails with many species may be restricted to a single valley.

Front 42

Rapid speciation can lead to evolutionary radiation. What is evolutionary radiation?

Back 42

Proliferation of many species from a single ancestor.

Front 43

What is adaptive radiation and what is an example?

Back 43

If the resulting species from evolutionary radiation live in a wide array of environments. For example, the Haiwaiian Islands and the 10,000 native species of insects that are believed to have evolved from 400 immigrant species.

Front 44

What is a genome?

Back 44

An organisms full set of genes plus noncoding regions of DNA.

Front 45

T/F:

In Eukaryotes, some DNA is in the mitochondria and chloroplasts.

Back 45

True

Front 46

What is molecular evolution?

Back 46

The process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations.

Front 47

What 3 ideas does molecular evolution include?

Back 47

1. Mechanisms and consequences of macromolecule evolution.

2. Relationships between gene structure and proteins and organism function.

3. using molecular variation to reconstruct evolutionary history.

Front 48

What does homologous mean?

Back 48

Shared by two species or inherited from a common ancestor.

Front 49

What is sequence alignment and its technique?

Back 49

Aligning amino acid sequences and determing insertion and deletion events that have occured since the two species diverged.

Front 50

What is a similarity matrix?

Back 50

A computer algorithm matrix that gives a measure of the minimum number of changes that have occured since the divergence of each pair of organisms.

Front 51

What is a limitation of a sequence alignment?

Back 51

The count provided of the changes in DNA underestimates the actual number of changes that have occurred since the sequences diverged.

Front 52

What are multiple substitutions?

Back 52

More than one change has occurred at a given position between the ancestral sequence and at least one of the observed sequences.

Front 53

What are coincident substitutions?

Back 53

At a given position, different substitutions have occurred between the ancestral sequence and each observed sequence. Basically, different substitutions in different descendants.

Front 54

What are parallel substitutions?

Back 54

The same substitution has occurred independently between the ancestral sequence and each observed sequence.

Front 55

What are back substitutions?

Back 55

Also known as reversions. After a change at a given position, a subsequent substitution has changed the position back to the ancestral state.

Front 56

What is a transversion change?

Back 56

Purines are replaced by a pyrimidine and vice versa.

Front 57

What is a transition change?

Back 57

Changes between the two purines A to G, or changes between pyrimidines C to T and vice verse. More common than transversions.

Front 58

What is the start codon for methylene?

Back 58

AUG

Front 59

What are some stop codons?

Back 59

UAA, UAG, and UGA

Front 60

What is a synonymous or silent mutation?

Back 60

Substitutions that do not change the encoded amino acid.

Front 61

What is are the two nonsynonymous substitutions?

Back 61

Misense substitutions and nonsense substitutions.

Front 62

What are misense substitutions?

Back 62

Changes in a specified amino acid.

Front 63

What are nonsense substitutions?

Back 63

Produces a stop codon and terminate the protein.

Front 64

What is positive selection in terms of substitutions?

Back 64

A replacement that confers an advantage to the organism.

Front 65

T/F:

Nonsynonymous substitutions are likely to be deleterious but may be selectively neutral if protein shape and function are not altered.

Back 65

True

Front 66

What are pseudogenes?

Back 66

Copies of genes that are no longer functional (and so not subject to strong selection). Has a much higher rate of substitution than regular genes.

Front 67

What does the neutral theory state?

Back 67

The majority of mutations are selectively neutral and accumulate through genetic drift, not positive selection.

Front 68

How are molecular clocks used?

Back 68

Used to calculate evolutionary divergence times between species if mutation rates are constant.

Front 69

T/F:

There is some correlation between genome size and organism complexity but larger does not always equal more complex.

Back 69

True

Front 70

What are 3 possible roles of non coding DNA?

Back 70

1. Regulatory functioncontrolling timing of gene expression.

2. Pseudogenes that are raw material for evolution.

3. Transposable elements that reproduce faster than the host genome.

Front 71

What are retrotranspons?

Back 71

Transposable elements that copy themselves through an RNA intermediate. Commonly carry long terminal repeats.

Front 72

T/F:

The number of orphaned LTRs (long terminal repeats) equals the number of retrotranspons that have been lost.

Back 72

True

Front 73

What is lateral gene transfer?

Back 73

Genes, organelles, or gene fragments moving horizontally from one lineage to another, seen commonly in plants.

Front 74

What are two advantages to lateral gene transfer?

Back 74

1. genes that have antibioticresistance are transmitted among bacteria species.

2. Increases genetic variation, providing new material for evolution.

Front 75

T/F:

Lateral gene transfer is relatively uncommon among most eukaryote lineages but endosymbiosis can be viewed as lateral transfer technically.

Back 75

True

Front 76

What are 4 possible fates for when gene duplications give rise to new protein functions?

Back 76

1. Both copies retain original function with more product created.

2. Both copies retain original function but expression diverges in different tissues or at different times.

3. Once copy accumulates deleterious substitutions and becomes either pseudogenes or eliminated.

4. Once copy accumulates substitutions that allow it to perform a new function.

Front 77

What are gene families?

Back 77

Genes created from successive rounds of duplication and mutation, like the globin gene family.

Front 78

T/F:

In polyploidy organisms, the whole genome is duplicated, allowing new functions to arise like with jawed fish.

Back 78

True

Front 79

What are the two forms of homology in genes since members of gene families have similar sequences?

Back 79

1. Orthologs

2. Paralogs

Front 80

What are orthologs?

Back 80

Homologous genes traced back to speciation events (external).

Front 81

What are paralogs?

Back 81

Homologous genes related through duplication events (internal).