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BIO 211 > Intro/Evolution > Flashcards

Intro/Evolution Flashcards

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Biology 101 flashcards
1
Q

List the characteristics of life.

A
  1. Living things contain nuclei acids, proteins, carbohydrates, and lipids
  2. Composed of cells
  3. Reproduction
  4. Use energy and raw materials
  5. Responds (to environment)
  6. Maintains homeostasis
  7. Populations evolve and have adaptive traits
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2
Q

List the levels of biological organization from smallest to largest.

A

Molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere

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3
Q

What usefulness does studying each biological level have?

A

Studying each individual level allowed emergent properties to be better observed.

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4
Q

What are emergent properties?

A

Novel properties that emerge that are absent from the preceding ones due to the arrangement of parts as complexity increases

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5
Q

What is evolution?

A

A process of biological change in which species accumulate differences from their ancestors as they adapt to different environments over time.

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6
Q

What mechanisms by which does evolution occur?

A

Natural selection, mutation, sexual selection (non-random mating), genetic drift, and gene flow

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7
Q

What is natural selection?

A

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits.

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8
Q

What does natural selection lead to and explain.

A

Descent with modification: as species adapt to different environments over time they accumulate differences from their ancestors.

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9
Q

Explain how natural selection works including:
A) what is required for it to take place
B) on what level of biological organization it works
C) the level of biological organization in which the outcome is apparent

A

A) members of the population must vary in trait. Natural selection can only amplify or diminish traits that differ among individuals, so if a population is genetically identical for a trait, natural selection can’t occur.
B) takes place on the phenotype of an organism (cellular technically)
C) the outcome of evolution is apparent only in the population

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10
Q

What is genetic variation?

A

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

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11
Q

How does genetic variation play a role in evolution?

A

In multicellular organisms, genetic variation can be found in gametes that will be passed onto offspring. In single felled organisms, genetic variation through mutations or other processes will be directly passed onto offspring.

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12
Q

What brings about genetic variation?

A

Mutations, gene duplication, sexual reproduction (crossing over, independent assortment of chromosomes, and fertilization) , gene translocation, and gene deletion.

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13
Q

What 4 data types document evolution?

A

Homology, direct observations, fossil record, and biogeography

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14
Q

What is adaptive selection and provide an example?

A

Traits that enhance survival or reproduction tend to increase in frequency over time
Allele frequencies for DDT resistance increased in flies over time but was once rare

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15
Q

What is genetic drift and the types of it?

A

Chance events that cause allele frequencies to fluctuate unpredictable from 1 generation to the next (usually in smaller populations)

Founder effect and bottleneck effect

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16
Q

Explain the founder effect.

A

When few individuals become isolated from a larger population. This smaller group may establish a new population whose gene pool differs from the source population.
Ex. 15 British people moved to an island and 1 had a recessive allele for blindness, which increase the risk of getting it there since they reproduced amongst themselves.

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17
Q

Explain the bottleneck effect.

A

A sudden change in environment that may drastically reduce the population size
Ex. Fire/flood- by chance alone some traits may be under or overrepresented in survivors.

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18
Q

What is gene flow?

A

The transfer of alleles into or out of populations due to the movement of fertile individuals or gametes.

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19
Q

What are the effects of genetic drift?

A
  1. It’s effects are greater in smaller populations
  2. Causes allele frequencies to change at random
  3. Loss of genetic variation in populations (which affects ability to adapt)
  4. Can cause harmful alleles to become fixed
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20
Q

What is an effect of gene flow?

A

It tend to decrease genetic differences between populations.
Ex. Insect pollination introducing genes

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21
Q

What is relative fitness?

A

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

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22
Q

What can lead to greater relative fitness and why?

A

Traits that help an organism survive will lead to greater relative fitness because natural selection leads to certain favorable traits that provides a reproductive advantage either through survival or some other effect.

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23
Q

How does natural selection alter the frequency distribution of heritable traits?

A

Directional, disruptive, and stabilizing selection

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24
Q

What is directional selection?

A

Conditions favor individuals exhibiting 1 extreme of a phenotype rang, thereby shifting a population’s frequency curve for the characteristic in 1 direction.
Ex. Most common during a population migration to a new habitat. Moving to a desert from a forest might make lighter coats in an organism more favorable.

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25
Q

What is disruptive selection?

A

Conditions favor individuals at both extremes of a phenotypic range over individuals with intermediated phenotypes
Ex. Small beak is good for soft seeds, and a large beak is good for hard seeds. However, intermediate beaks are bad for both.

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26
Q

What is stabilizing selection?

A

Acts against both extreme phenotypes and favors intermediate variants.
Ex. Fat and underweight babies have a higher mortality

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27
Q

What is one effect of stabilizing selection?

A

It reduces genetic variation by favoring the intermediate phenotype.

28
Q

What effects do both genetic drift and gene flow have?

A

They enhance survival and reproduction but not consistently.

29
Q

What is sexual selection?

A

A process in which individuals with certain inherited traits are more likely than other individuals of the same sex to obtain mates.

30
Q

What is sexual dimorphism and what causes it?

A

A difference in secondary sexual characteristics between males and females of same species like size, color, ornamentation, and behavior.
Can caused by sexual selection.

31
Q

What is intrasexual selection?

A

Selection within the same sex Ex. Competition among 1 sex for mates

32
Q

What is intersexual selection?

A

Aka mate choice- individuals of 1 sex (usually females) are choosy in selecting their mates
Depends on showiness of male appearance and behavior sometimes

33
Q

What is balancing selection?

A

A selection that may preserve variation at some loci, thus maintaining two plus phenotypic forms in the population

34
Q

What is frequency dependent selection?

A

The fitness of a phenotype depends on how common traits in a population
Ex. Prey guarda more against when left or right mouthed fish are more common

35
Q

What is heterozygous advantage?

A

If individuals who are heterozygous at a particular locus have greater fitness than do both types of homozygous individuals

36
Q

How are balancing selection, frequency dependent selection, and heterozygous advantage defined?

A

Defined in genotype, not in phenotype (unlike natural selection)

37
Q

Why doesn’t natural selection make perfect organisms?

A
  1. Selection only acts on existing variation
  2. Evolution is limited to historical constraints (depends on ancestors too)
  3. Adaptations are often compromises
  4. Chance, natural selection, and the environment interact
38
Q

What is speciation?

A

The process by which 1 species splits into 2 species

39
Q

What does speciation lead to?

A

Leads to diversity and shows the unity of life

40
Q

Define micro evolution?

A

Changes over time in allele frequencies in a population

41
Q

Define macro evolution.

A

The broad pattern of evolution above the species level

42
Q

What is the biological species concept?

A

A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with members of other such groups

43
Q

What can lead to speciation?

A

A reduction of gene flow because it holds populations together genetically since it occurs between different populations of groups and species.

44
Q

What is reproductive isolation?

A

The existence of biological barriers that impede members of 2 species from interbreeding and producing viable, fertile offspring

45
Q

What are prezygotic barriers?

A

Block fertilization from occurring

Ex. Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

46
Q

What is habitat isolation?

A

Occupy different habitats within the same area and encounter each other rarely

47
Q

What is temporal isolation?

A

Breed at different times

48
Q

What is behavioral isolation?

A

Courtship rituals that are unique to a species

49
Q

What is mechanical isolation?

A

Mating attempted but morphological differences make it unsuccessful

50
Q

What is gametic isolation?

A

Sperm of 1 species can’t fertilize the eggs of another

51
Q

What are postzygotic barriers?

A

Contribute to reproductive isolation after the zygote is formed
Ex. Reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

52
Q

What is reduced hybrid viability?

A

Genes of parents interact to impair hybrid development and survival

53
Q

What is reduced hydride fertility?

A

Chromosomes of parents different in structure and number so it can’t produce normal gametes

54
Q

What is hybrid breakdown?

A

If a mate with either parent species produces feeble or sterile offspring

55
Q

What is morphological species concept?

A

Distinguishes species by body shape and other structural features

56
Q

What is ecological species concept?

A

Defines a species in terms of its ecological niche

57
Q

What is allopathic speciation?

A

Gene flow is interrupted when a population is divided into geographically isolated sub populations

58
Q

What leads to reproductive isolation?

A

After gene pools diverge because of different mutations, natural selection, and genetic drift

59
Q

Where is there more likely to be more species?

A

Regions that are isolated or have highly subdivided barriers Ex. Hawaii

60
Q

What is sympatric speciation?

A
  • Occurs in populations that live in the same geographic area
  • less common
  • when gene flow is reduced by factors like polyploidy, sexual selection, and habitat differences
61
Q

Explain sexual selection of chiclids and its effects.

A

Sexual selection based on female preferences for certain male olores has resulted in reproductive sympatric speciation. This has led to the creation of many chiclids (especially within one freshwater lake in the US).

62
Q

What is one prezygotic barrier that can lead to sympatric speciation?

A

Habitat isolation- when a subpopulation exploits a habitat or resource that is not used by the parent population
Ex. Flies- when apple trees were introduced, flies that lived there instead of the thorn trees mated instead. Apple trees also matured faster, so rapid development was favored, which led to temporal isolation.

63
Q

What does sympatric speciation require?

A

The creation of reproductive barriers for isolation (these are not physical barriers but biological barriers)

64
Q

What is punctuated equilibrium?

A

Periods of apparent stasis punctuated by sudden change (once proves of speciation begins, it can be completed quickly)

65
Q

Why can it be hard to find evidence of punctuated equilibrium in the fossil record?

A

sometimes a short period of fossils like say 50,000 years would not allow for an extra layer of sediment to form to show the gradual changes. This makes it seem like all of a sudden the organism as a population changed suddenly.

66
Q

What are some limitations to the biological species concept?

A

It does not apply to asexually reproducing organisms.

67
Q

What are the steps of speciation?

A
  1. Isolation- populations become genetically isolated (usually geographically)
  2. Populations diverge in traits
  3. Reinforcement- reproductive isolation between populations

BIO 211 (5 decks)

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