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BIO102 > Ch. 16, 17, 18 Evolution > Flashcards

Ch. 16, 17, 18 Evolution Flashcards

1
Q

how do we know evolution exist?

A

by studies in anatomy, embryology, molecular biology, and biogeography

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2
Q

how evolution leads to natural selection

A
  • some traits of an individual are more adaptive to changing environment
  • more offspring are produced with favorable genes so the resources, reproduction and survival are limited
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3
Q

Charles Darwin

A

along with Wallace, came to the idea of natural selection around 1858
- published a controversial “On the Origin of Species”

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4
Q

adaptation

A

a heritable trait that helps the survival and reproduction of an organism in its present environment

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5
Q

the basis of variation

A

genetic variation

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6
Q

types of genetic variation

A
  • dimorphic

- polymorphic

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7
Q

dimorphic trait

A

traits with 2 distinct forms: white or purple flowers on pea plants

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8
Q

polymorphic trait

A

traits with more that 2 distinct forms: ABO blood type in humans

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9
Q

basis of genetic variation

A

mutation (change in DNA pattern)

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10
Q

mutation types

A
  • neutral: no effect on survival or reproduction
  • lethal: ends in death
  • beneficial: gives slight advantage toward survival and reproduction
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11
Q

sources of mutations

A
  • random genetic changes
  • crossing over in Meiosis I
  • independent assortment in Meiosis I
  • fertilization
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12
Q

gene pool

A

sum of all genes in a population

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13
Q

allele frequency

A

rate at which a specific allele is present within a population

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14
Q

microevolution

A

change in allele frequency in gene pool

-always occurring in natural populations due to mutations and/or natural selection

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15
Q

macroevolution

A

large scale evolutionary pattern above the species level

-ex. land plants evolving from algae, extinction of dinosaurs

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16
Q

the two main evolution types

A
  • divergent evolution

- convergent evolution

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17
Q

divergent evolution

A

changes in body or form from a common ancestor

ex. homologous structures (limbs of vertebrate animals)
- flight in birds and bats
- flippers in penguins and porpoises

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18
Q

homologous structures

A

structures in organisms that share the same basic form

  • same genes direct their development
  • may be used for different purposes
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19
Q

vestigial structures

A

structures that exist in organisms but seem to have no apparent function

  • -appear to be residual parts from a past common ancestor–
  • ex. appendix in humans, pelvis on snakes, goosebumps
20
Q

convergent evolution

A

when traits evolve similarly in species that do not appear to have a common ancestor
-have analogous structures
due to similar selection pressures
-may perform the same function because of environment pressures

21
Q

analogous structures

A

structures that look alike but evolved independently

22
Q

transitional soforms

A

an intermediate form of an organism linking two other organisms together

23
Q

patterns of natural selection

A
  • directional selection
  • stabilizing selection
  • disruptive selection
24
Q

directional selection

A

an extreme trait is more favorable

25
Q

stabilizing selection

A

an intermediate trait is more favorable

26
Q

disruptive selection

A

extremely different traits are more adaptive and favorable

27
Q

natural selection and diversity

A

sexual dimorphism different looking male and females
- due to sexual selection: traits to better attract mates
females either choose mate(s) or males compete for a group of females

28
Q

balanced polymorphism and the heterozygote

A

two or more alleles continue circulating at a relatively high frequency in a population

  • arises in nature favoring the heterozygotes
    ex. sickle cell anemia and malaria resistance
29
Q

the level of genetic variance

A
  • are best maintained with sexual reproduction as genetically different parents create diverse children
  • best to avoid asexual reproduction which leads to clones
30
Q

non-selective evolution (evolution by “chance”)

A
  • genetic drift

- fixed allele

31
Q

genetic drift

A

random chance in allele’s frequency over time, brought by chance alone
-by chance to be in the right place at right time or wrong place wrong time

32
Q

type of genetic drifts

A
  • bottleneck: results in large part of the population getting wiped out
  • founder effect: small group establishes a new population
33
Q

fixed allele

A

individuals for allele are all homozygous

-common among small populations

34
Q

gene flow

A

movement of alleles between populations

-can result in change or stabilization of allele frequencies

35
Q

speciation

A

evolutionary process in which new species form

  • occurs when populations cross breed (not interbreed)
  • increase the number of genetic variation/differences
  • over time they become so different we call them different species
36
Q

types of speciation

A
  • allopatric speciation
  • parapatric speciation
  • sympatric speciation
37
Q

allopatric speciation

A

arises from physical separation between populations

  • reproductive isolation
  • geographic isolation
38
Q

reproductive isolation

A

biological/physical barrier gene flow

  • influenced by how an organism reproduces
  • can prevent interbreed–even if populations meet again
  • -have pre-zygotic and post-zygotic factors
39
Q

geographic isolation

A

physical geographical barriers to gene pool

*influenced by how species travel

40
Q

hybrid

A

cross between 2 different species that are similar

41
Q

sympatric speciation

A

populations inhabiting same regions with no physical barriers between them
- can occur in single generations when chromosome number multiplies
-also occurs with no number change
more common in plants

42
Q

parapatric speciation

A

adjacent populations speciated despite being in contact across common borders

  • divergences spurred by local pressures are reinforced
    ex. velvet walking worm
  • hybrids that are formed in contact zone are not better fit
43
Q

adaptive radiation

A

organisms that do not go extinct may go under adaptive radiation

  • key innovation
  • co-evolution
44
Q

key innovation

A

new trait that allows one organism to exploit a habitat more effectively

45
Q

co-evolution

A

two species evolve jointly because of close ecological connection

BIO102 (4 decks)

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