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BS 162 > Exam 2 > Flashcards

Exam 2 Flashcards

0
Q

Bottleneck Effect?

A

occurs when some event reduces the pop to a really small size. Genetic Drift.

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1
Q

What are the 5 requirements for the Hardy-Weinberg Equilibrium?

A
  1. A Small Population causes genetic drift (changes in allele freq dur to chance) ex Bottleneck Eff and Founder Eff
  2. Non-Isolated pop causes gene flow (reduces genetic diff b/n pops- when individuals move from one pop to another)
  3. Mutations cause new alleles to be introduced into pop
  4. Nonrandom mating causes more expression of recessive phenotypes. Ex Inbreeding and Assortative mating. (recessive genes more likely to pair up so recessive pheno)
  5. Natural selection causes the expression of successful alleles
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2
Q

Founder Effect?

A

Occurs when a few individuals colonize a new area. Genetic Drift

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3
Q

Assortative mating?

A

Individuals choose partners like themselves. Makes recessive phenotypes more likely.

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4
Q

What does it mean when the Hardy-Weinburg Equilibrium is met?

A

No evolution occurs.
Five standards must be met: pop must be v large, pop must be isolated from other pops (no immigration or emigration), no mutations, random mating, no natural selection.
No change in allele freq

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5
Q

Macroevolution?

A

Major evolutionary changes over time. Origin of new types of organisms from previously existing but diff ancestral types. New species created.Change in MANY gene freq resulting in new species creation.

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6
Q

Microevolution?

A

Changes of organism within a specific group. Trait within a specific species is found to be preferable to natural selection and this trait prevails. Exists by recombining existing genetic info within the group.
Change in gene freq for one or two traits.

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7
Q

How/why Genetic Drift affects allele freq?

A

Smaller gene pools increase probability of deviations from normal. Loss of genetic variation.

  1. significant for small pops
  2. can cause allele freq to change at random
    >unlike natural selection where allele freq is predictable from year to year, genetic drift is unpredictable, changes and varies over time.
  3. can lead to a loss of genetic variation
  4. can cause harmful alleles to be more likely
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8
Q

Artificial vs Natural selection

A

In artificial selection, humans select for the traits they desire in plants or animals. In natural, they are more likely to reproduce because of this particular trait.

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9
Q

Sexual Dimorphism?

A

Diff between the two sexes in secondary sex characteristics due to sexual selection.

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10
Q

Intrasexual Selection?

A

members of one sex compete directly for mates of the opposite sex. One male guards a bunch of females from other males and fights to mate.

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11
Q

Intersexual Selection?

A

“mate choice” individuals of one sex (usually the females) are choosy in selecting their mates of the other sex. Females prefer male traits that are correlated with “good genes”

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12
Q

Heterozygous Advantage?

A

if individuals who are heterozy at a particular locus have greater fitness that do both kinds of homozy. Defined in terms of genotype NOT phenotype. If hetero for beta polypep subunit of hemoglobin, oxy carrying protein of RBCs, less sickle cells in sickle cell disease. Also, protected against malaria.

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13
Q

Benefits to heterozygous MHC?

A

more resistant to parasites than homozygous MHC. More capable of recognizing a wider range of pathogens and therefore inciting a specific immune response against a greater number of pathogens.

More likely to reproduce/more desirable

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14
Q

Logical basis of Natural Selection

A

Species have a high reproductive potential, however- pops tend to remain stable because resources are limited. Individuals vary in a pop. Most variation is inherited. Differential survival and reproduction: fittest survive and reproduce, leads to a gradual change in pop over time.

Populations NOT individuals adapt to their environment

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15
Q

Darwin influenced by

A

Lyell’s principles of geology. Uniformitarianism: old Earth with gradual changes.

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16
Q

Alfred Russel Wallace influenced by

A

Lyell and uniformitarianism. Malthus: survival of the fittest. Human pops about the same despite potential to reproduce- famine and wars kept pop the same.

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17
Q

Sources of Variation in a Pop?

A

Non-Heritable Variation: environment induced differences (some survival traits effected by environmental change)

Heritable Variation: Polymorphism- distinct forms of traits in pop like human’s diff blood types.

Geographic Variation: Individuals adapt to local environment

Mutation: Changes in DNA, fundamental reason for variation.

Sexual recombination: meiosis (ind assortment and crossing over)

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18
Q

Ways that variation is preserved in a pop?

A

Diploidy: alleles can hide in a heterozygote

Variable selection: sometimes one thing is beneficial, sometimes other thing is.

Balanced Polymorphy: Heterozygote advantage- hetero do better than homo. why pure bred dogs don’t do as well as mutts.

Freq Balanced selection: both morphs do better when two morphs are present.

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19
Q

Directional Natural Selection?

A

Occurs when conditions favor individuals exhibiting one extreme of a phenotypic range. Shifts curve in one direction or the other.

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20
Q

Disruptive Natural Selection?

A

Occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes. Goes from bell curve to “M”

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21
Q

Stabilizing selection?

A

Acts against both extreme phenotypes and favors intermediate variants. Maintains the status quo for a particular phenotypic character. Bell curve becomes more pointed.

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22
Q

Biological Species Concept

A

A species is a group of pops whose members have the potential to interbreed in nature and produce viable offspring. Thus, members of a species are united by being reproductively compatible.

23
Q

Prezygotic Barriers

A

block fertilization from occuring. Before sperm can get to ovum to fertilize it. part of reproductive isolation that supports the biological species concept.

24
Q

Postzygotic Barriers

A

What stops different species from making offspring after ovum is fertilized by sperm. Ex: developmental errors or problems after birth that may cause hybrids to be infertile etc

25
Q

Habitat Isolation

A

Prezygotic barrier. two species occupy diff habitats within same area but never encounter each other. not isolated by physical barriers though. Ex one species in water and other in trees

26
Q

Temporal Isolation

A

Prezygotic Barrier. Species breed during diff times of the day, seasons, or diff years cannot mix their gametes.

27
Q

Behavioral Isolation

A

Prezygotic Isolation. Mate recognition behaviors are different so that they don’t recognize the other animal as viable mates

28
Q

Mechanical Isolation

A

Prezygotic Isolation. Mating is attempted but morphological diff prevent its successful completion.

29
Q

Gametic Isolation

A

Prezyotic Isolation. Sperm of one species may not be able to fertilize the eggs of another species.

30
Q

Reduced Hybrid Viability

A

Postzygotic Barrier. Genes of diff parent species may interact in ways that impair the hybrid’s development or survival in environment

31
Q

Reduced Hybrid Fertility

A

Postzygotic Barrier. Hybrid is sterile

32
Q

Hybrid Breakdown

A

Postzygotic Barrier. Some of first gen of hybrids are viable and fertile but when they mate with one another or parent species, offspring of next gen are feeble or sterile

33
Q

Allopatric Speciation

A

Gene flow is interrupted when a pop is divided into geographically isolated subpops

34
Q

Sympatric Speciation

A

Speciation occurs in pops that live in the same geographic area. Gene flow reduced by polyploidy, habitat differentiation, and sexual selection.

35
Q

Autopolyploidy

A

an individual that as more than 2 chromosomes sets that are all derived from a single species. Increases the ploidy of offspring. Can lead to sympatric speciation.

36
Q

Punctuated Equilibrium

A

periods of stasis in evolution punctuated by sudden change. Counterpart= graduated equilibrium which is constant small changes in evolution over time

37
Q

Four Eras?

A

Archaean, Proterozoic, Paleozoic, Mesozoic, Cenozoic

38
Q

Archaean Era Key Facts

A

Prokaryotes appear, oldest known rocks on Earth appear. 4600 to 2500 million years ago. End of it was when atmospheric oxygen began to increase.

39
Q

Proterozoic Era Key Facts

A

Oldest fossils of Eukaryotes appear.diverse algae and soft bodied invertebrates. 2500 to 542 million years ago

40
Q

Paleozoic Key Facts

A

542-251 million years ago. Sudden increase in diversity of many animal phyla. Cambrian Explosion! Prior to this explosion all animals were soft bodied: lots of grazers, suspension feeders, or scavengers. No hunters. This explosion brought hunters. Vascular plants develop. Reptiles develop. Extinction of many marine and terrestrial organisms at the end of this period due to the Permian Extinction.

41
Q

Permian Extinction

A

In Permian part of Paleozoic era which marks end of this era and beginning of Mesozoic. Due to lots of volcanic eruptions around Siberia. Lots of volcanic ash and stuff raised earth’s temp, decrease oxygen, and carbon dioxide. Warmed oceans. Killed a hella lot of animals.

42
Q

Mesozoic Key Facts

A

251 to 65.5 million years ago.Cone bearing plants appeared, dinosaurs (rawr), origin of mammals, flowering plants. Dinosaurs became extinct at the end of this period. This era ended by Cretaceous mass extinction.

43
Q

Cretaceous Mass Extinction

A

Marks end of Mesozoic and beginning of Cenozoic era. Wiped out all dinos and lots of other animals. Due to meteorite. Blocked sun and severely disturbed the global climate for several months.

44
Q

Cenozoic era Key Facts

A

Beginning marked by Cretaceous Mass Extinction 65.5 million years ago to present day. Origin of many primates, angiosperm dom increases, origin of genus Homo

45
Q

Radiometric Dating

A

is actual dating in years. parent isotope decays to daughter isotope at a fixed rate. Rate of decay= half life, the time required for 50% of the parent isotope to decay

46
Q

Plate Technotics: History of continental drift

A

Paleozoic Era: Pangea supercontinent
Mesozoic Era: mid mesozoic- pangea split into two landmasses
End of Mesozoic: Today’s continents
Cenozoic: 45 million years ago, Himalayas began to form. The continents continue to drift today

47
Q

HOX Genes

A 
Homeobox (HOX) Genes
Master reg genes
depends on what segment cels are in
specify what appendage is coded for
head--->antennae
thorax--->legs
hox genes are repeated on many chromosomes
many homologies in animal phyla
Used to tell history of evolution
48
Q

Rules of Cladistics

A

assumes monophyletic groups
each group has a single, common ancestor
any two species, somewhere in their line have a common ancestor
Dichotomous branching: single forks
if mult forks, then phylogeny uncertain
Uses parsimony (=Occams’s razor)
William of Occam: 1300s Franciscan monk
Bertrand Russell: “It’s vain to do with more than what can be done with fewer”
Principal of parsimony: fewest explanations
tree with fewest evolutionary steps is best

49
Q

Monophyletic

A

signifying that a taxon consists of an ancestral species with all of its descendants

50
Q

Paraphyletic

A

consists of an ancestral species and some but not all of its decendants

51
Q

polyphyletic

A

includes taxa with different ancestors

52
Q

Convergent Evolution

A

evolution of similar traits or characteristics from different lineages- animals not related at all

53
Q

Divergent Evolution

A

Formation of differences between the group which can lead to new species

54
Q

Synapomorphy

A

In cladistics, a synapomorphy or synapomorphic character state is a trait that is shared by two or more taxa and inferred to have been present in their most recent common ancestor, whose own ancestor in turn is inferred to not possess the trait.

55
Q

Synplesiomorphies

A

In cladistics, a symplesiomorphy or symplesiomorphic character is an ancestral trait shared by two or more taxa. No relationship of characteristic. Ex: Humans have hair binocular vision and canines but so do monkeys

BS 162 (1 decks)

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