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BIO 202 > CH 23 & 25: Evolution > Flashcards

CH 23 & 25: Evolution Flashcards

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Biology 101 flashcards
1
Q

What is evolution?

A

Heritable change in one or more characteristics from one generation to the next

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2
Q

What is microevolution?

A

changes in a single gene in a population over time

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3
Q

What is macroevolution?

A

formation of new species or groups of species

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4
Q

What influence did the Uniformitarianism hypothesis from geology have on Darwin’s theory of evolution?

A
  • Slow geological processes lead to substantial change

- Earth was much older than 6,000 years

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5
Q

What did Darwin call his theory of evolution?

A

Descent with modification

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6
Q

What influence did Thomas Malthus, an economist, have on Darwin’s theory of evolution?

A

Only a fraction of any population will survive and reproduce

Population growth limited by:
•Famine
•War
•Disease

Survival & reproduction are key components of natural selection

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7
Q

What is descent with modification, evolution, based on?

A

Variation within a given species
•Traits heritable –passed from parent to offspring
•Genetic basis was not yet known

Natural selection
•More offspring produced than can survive
•Competition for limited resources
•Individual with better traits flourish and reproduce

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8
Q

What animal did Darwin study on the galapagos that influenced his theory of evolution?

A

Finches and their beak size

  • finches from south american mainland flew to galapagos with variety of beak sizes (ie. variation)
  • natural selection weeded out beak sizes that weren’t conducive to eating galapagos seed and nuts
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9
Q

What evidence is there for the theory of evolution?

A

-Fossil record
-Biogeography
-Convergent evolution
-Selective breeding
-Homologies (morphology/DNA)
•Anatomical
•Developmental
•Molecular

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10
Q

What is the evidence of evolutionary change in the fossil record?

A
  • Evolution of the horse ~ ex of how evolution involves adaptation to changing environments
  • changes in size, foot anatomy, and tooth morphology
  • Changes because natural selection producing adaptations to changing global climates
  • Large dense forests replaced with grassland
  • Run faster, eat tougher food
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11
Q

What is the evidence of evolutionary change in biogeography?

A

Study of the geographical distribution of extinct and modern species
•Isolated continents and islands evolve their own distinct plant and animal communities
•Closely related species living in isolation become divergent
•Endemic–naturally found only in a particular location

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12
Q

What is the evidence of evolutionary change in convergent evolution?

A

Two different species, without common ancestor, show similar characteristics because they occupy similar environments
•Suggests adaptation to the environment

Examples:
•Antifreeze proteins in different, very cold water fish

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13
Q

What is the evidence of evolutionary change in Selective breeding?

A

Programs and procedures designed to modify traits in domesticated species
•Also called artificial selection
•Nature chooses parents in natural selection while breeders choose in artificial selection
•Made possible by genetic variation

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14
Q

What is the evidence of evolutionary change in homology?

A

Fundamental similarity due to descent from a common ancestor

Homology may be any inherited type of character
•Anatomical
•Developmental
•Molecular

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15
Q

What is the evidence of evolutionary change in anatomical homology?

A

Same set of bones in the limbs of modern vertebrates has undergone evolutionary change for many different purposes
•Homologous structures are derived from a common ancestor
•Vestigial structures are anatomical structures that have no function but resemble structures of ancestors

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16
Q

What is the evidence of evolutionary change in developmental homology?

A

Species that differ as adults have similarities during embryonic stages
•Presence of gill ridges in human embryos indicates humans evolved from an aquatic animal with gill slits
•Human embryos have long bony tails

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17
Q

What is the evidence of evolutionary change in molecular homology?

A

Similarities in cells at the molecular level show that living species evolved from a common ancestor
•same type of gene is often found in DNA of diverse organisms
•Sequences of closely related species tend to be more similar to each other than to distantly related species

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18
Q

What are Homologous Genes?

A

Two genes derived from the same ancestral gene

19
Q

What are Orthologs?

A

Genes in different species that evolved from a common ancestral gene by speciation
-The genes have similar functions

20
Q

What is a Gene Family?

A

A set of Several similar genes formed by duplication of a single original gene

21
Q

What is a Paralog?

A

two or more homologous genes derived from the same ancestral gene at different locations
-The genes do different functions

22
Q

When does a homologous gene become an ortholog?

A

When mutations accumulate enough so the two genes are not identical anymore

23
Q

What is Macroevolution?

A

evolutionary changes that create new species and groups of species

24
Q

What is a species?

A

Group of organisms that maintains a distinctive set of attributes in nature

25
Q

What characteristics are commonly used to identify a species?

A

1) Morphological Traits
2) Ability to Interbreed (reproductive isolation)
3) Molecular Features
4) Ecological Factors
5) Evolutionary Relationships

26
Q

What are Morphological Characteristics? What are the drawbacks to using it to identify a species?

A
  • Physical Characteristics of organism

- How many traits to consider? Same species can look different. Different species can look similar.

27
Q

What is the ability to interbreed? What are the drawbacks to using it to identify a species?

A
  • Reproductive isolation prevents one species from successfully interbreeding with another species
  • Difficult to determine in nature, some species’ can interbreed but don’t, Doesn’t apply to asexual species, can’t be applies to extinct species
28
Q

What are Molecular Features? What are the drawbacks to using it to identify a species?

A

Compare features to identify similarities/differences among different populations

  • DNA sequences within genes
  • Gene Order along chromosomes
  • Chromosome structure
  • Chromosome Number

Difficult to draw the line when separating groups

29
Q

What are Ecological Factors? What are the drawbacks to using it to identify a species?

A

Factors related to organism’s habitat

  • Different species display similarities in habitat
  • Same species display differences in habitat
30
Q

What are the different species concepts?

A

Biological Species Concept: species can interbreed

Ecological Species Concept: Each species occupies ecological niche

Evolutionary Lineage Concept: Species based on separate evolution of lineages

31
Q

What is speciation?

A

formation of a new species

32
Q

What is the cause of speciation?

A

accumulation of genetic changes that cause enough differences to create a separate species

33
Q

What are the mechanisms of speciation?

A

Reproductive Isolation

  • Prezygotic Barriers: prevent formation of zygote
  • Postzygotic Barriers: block development of viable zygote
34
Q

What are the types of Prezygotic barriers?

A

Habitat Isolation: Geographic barrier prevents contact

Temporal Isolation: Reproduce at different times of the day or year

Behavioral Isolation: Behaviors important in mate choice

35
Q

What are the types of Postzygotic barriers?

A

Hybrid Inviability: Fertilized egg can’t proceed past early embryo

Hybrid Sterility: Interspecies hybrid viable but sterile

Hybrid Breakdown: Hybrids viable and fertile but have genetic abnormalities

36
Q

How does Speciation occur?

A

Cladogenesis: Division of a species into two or more species

-Requires gene flow between populations to be interrupted

37
Q

What are the types of Cladogenesis?

A

Allopatric Speciation
-When some members of species become geographically separated. Most Common.

Sympatric Speciation
-Members of specie diverge into two or more different species even though there are no physical barriers to interbreeding

38
Q

How can allopatric speciation occur when a small population moves to a new location that is geographically separated?

A

Natural selection
-Alters genetic composition of population leading to adaptation to new environment

Adaptive Radiation
-Single species evolves into array of descendants that differ greatly

39
Q

What are the mechanisms of Sympatric Speciation?

A

Polyploidy
-Automatic b/c extra genes cause sterility

Adaptation to Local Environment
-geographic area may have variation so members diverge to occupy different local environments

Sexual Selection
-Eventually don’t want to mate with other members of your species that vary slightly from yourself

40
Q

What is a hybrid zone?

A

zone where two population can interbreed
-geographic separation is not complete

Once gene flow though hybrid zone is greatly diminished, the two populations are reproductively isolated

41
Q

What are the two main hypotheses for the pace of speciation?

A

Gradualism and Punctuated Equilibrium

42
Q

What is Gradualism?

A

Each new species evolves continuously over long spans of time
-Large phenotypic differences due to accumulation of many small genetic changes

43
Q

What is Punctuated Equilibrium?

A

Tempo of speciation more sporadic

-long periods of equilibrium and the short rapid bursts of change

44
Q

Do species evolve slowly or quickly?

A

Both, fossil records provide evidence for both

-Generation time influences speed of evolution (ie. microbial vs. humans)

BIO 202 (21 decks)

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