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Bio 100 > Evolution > Flashcards

Evolution Flashcards

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Biology 101 flashcards
1
Q

What theory of classification did Aristotle propose?

A

Scala Naturae:
-Species are fixed
-arranges species on a scale of increasing complexity

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2
Q

What two principles did Lamarck propose?

A
  1. Use and disuse: body parts used extensively become
    larger and stronger, unused parts deteriorate
  2. Inheritance of acquired characteristics: modifications
    acquired in one’s lifetime can be passed to offspring(not true)
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3
Q

Descent with modification

A

all of life is connected by common ancestry and
descendants have accumulated adaptations to
changing environments over vast spans of time.

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4
Q

Key features of natural selection

A
  • Individuals with certain heritable traits survive and reproduce at a higher rate than other individuals
  • Natural selection increases the frequency of adaptations that are favorable in an environment
  • If the environment changes, natural selection may drive adaptation to new conditions, giving rise to new species
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5
Q

4 key points about evolution by natural selection

A
  1. individuals do not evolve as it is the population, the
    group of organisms, that evolves over time.
  2. natural selection can amplify or diminish only
    heritable traits.
  3. evolution is not goal directed; it does not lead to
    perfectly adapted organisms.
  4. selection happens by the environment/ ecosystem,
    not by the individuals themselves
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6
Q

How have we come across our current understanding of evolution?

A

Fossils: understanding of similarities, species come and
go
* Homology: similarities in form, behaviour etc.
* Molecular biology: biochemical assays on ancient and
modern samples
* Genomics: sequencing of ancient and modern genomes,
and looking for genetic changes

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7
Q

Homology

A

Similarity resulting from common ancestry

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8
Q

Vestigial structures

A

remnants of features that served important
functions in the organism’s ancestors

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9
Q

What similarities are looked for in molecular biology that can link species’ evolutionary relationships?

A
  • Similarities/ differences in
    protein structure
  • Similarities in cell structure
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10
Q

Genome Sequencing

A

is a laboratory procedure that determines the order of bases in the genome of an organism in one process. Can determine how genetically similar a species is to another.

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11
Q

Phylogeny

A

The evolutionary history of a species or group of species

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12
Q

Systematics

A

classifying organisms and determining their evolutionary
relationships
-includes taxonomy

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13
Q

Convergent evolution

A

occurs when similar
environments and natural selection produce similar
adaptations in organisms from different evolutionary lineages

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14
Q

Analogy

A

Similarity due to convergent evolution

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15
Q

Difference between homology and analogy

A

-Similarity resulting
from common
ancestry is known
as homology.
-Analogy: similar environments
and natural selection produce
similar adaptations

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16
Q

Molecular systematics

A

uses molecular comparisons to build phylogenetic trees.

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17
Q

Steps in the analysis before drawing a phylogenetic tree

A

1.organize the data: count the number of traits each species has
2.rank the species from lowest to highest number of traits.
3.identify the outgroup, the group with the fewest traits in the table
4.draw a phylogenetic tree, starting with the species with the least traits
5.indicate for each branching point which trait is developed.

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18
Q

Mutation

A

can occur due to errors in DNA replication (S-phase!)

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19
Q

mixing existing alleles arise every generation from which three random components of sexual reproduction?

A
  1. crossing over,
  2. independent orientation of
    homologous chromosomes at
    metaphase I of meiosis, and
  3. random fertilization.
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20
Q

Gene pool

A

consists of all copies of every type of allele, at every locus, in all members of the population.

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21
Q

Microevolution

A

Changes in the traits of a group of organisms within a species that do not result in a new species.

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22
Q

Macroevolution

A

Large-scale evolution occurring over geologic time that
results in the formation of new species and broader
taxonomic groups.
– the development of new groups of organisms through
speciation events
– the impact of mass extinctions and recovery on the
diversity of life

23
Q

Main causes of evolutionary change:

A
  1. natural selection,
  2. genetic drift
  3. gene flow
24
Q

Genetic drift

A

random events that drive genetic change of a population

25
Q

Fixation

A

rise to 100% percent frequency of other alleles

26
Q

Bottleneck effect

A

sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities

27
Q

Founders effect

A

when a few individuals
colonize an island or other new habitat

28
Q

Gene flow

A

Organisms and gametes that enter a population may have
new alleles, or may bring in existing alleles but in different
proportions than those already in the population.

29
Q

Stabilizing selection

A

favours intermediate phenotypes. For example in number of offspring or birthweight.

30
Q

Directional selection

A

individuals at one of the
phenotypic extremes. shifts the overall makeup of the population by acting
against individuals at one
of the phenotypic extremes. Examples: sickle cell anemia in malaria areas, shorter extremities in cold areas.

31
Q

Disruptive selection

A

both ends of a phenotypic
range over individuals with intermediate phenotypes. typically occurs when environmental
conditions vary in a way that
favors individuals at both ends of a phenotypic range over
individuals with intermediate
phenotypes. Examples: Peppered moths in polluted vs. non-polluted areas.

32
Q

Sexual selection

A

a form of natural selection in which individuals with certain characteristics are more likely than other individuals to obtain mates

33
Q

Intrasexual selection

A

individuals compete directly
with members of the same
sex for mates

34
Q

Intersexual selection

A

individuals of one sex (usually
females) are choosy in
selecting their mates.

35
Q

What constraints are placed on evolution?

A
  1. Selection can act only on existing variations. New,
    advantageous alleles do not arise on demand.
  2. Evolution is limited by historical constraints. Evolution
    co-opts existing structures and adapts them to new
    situations.
  3. Adaptations are often compromises. The same
    structure often performs many functions.
  4. Chance, natural selection, and the environment
    interact. Environments often change unpredictably
36
Q

Speciation

A

the process by which one species splits into two or more species

37
Q

Biological species

A

– a species is a group of populations whose members
can interbreed in nature and
– produce fertile offspring with each other but not with
members of other species.
– reproductive isolation.

38
Q

Morphological species concept

A

based on observable physical traits and can be applied to asexual organisms and fossils

39
Q

Ecological species concept

A

defines a species by its
ecological niche and focuses on unique adaptations to
particular roles in a biological community

40
Q

Phylogenetic species concept

A

defines a species as
the smallest group of individuals that share a common
ancestor and thus form one branch of the tree of life

41
Q

Allopatric speciation

A

Geographically separated from other populations,
a small population may become genetically unique
as its gene pool is changed by
– natural selection,
– mutation, or
– genetic drift.
Habitat differentiation and sexual selection, usually
involving mate choice, can lead to sympatric and allopatric speciation.

42
Q

Sympatric speciation

A

occurs when a new species arises within the same geographic area as its parent species. Habitat differentiation and sexual selection, usually
involving mate choice, can lead to sympatric and allopatric speciation.

43
Q

Polyploidy

A

duplication of the chromosome number due to errors in
cell division.

44
Q

What are the mechanisms of macroevolution

A
  • Plate tectonics
  • Gene flow, genetic drift, selection, adaptation, isolation à
    Speciation
  • Mass extinctions followed by adaptive radiation
45
Q

Pangea

A

About 250 million years ago, plate movements brought all the previously separated landmasses together into the
supercontinent

46
Q

Ordovician-silurian extinction

A

440 million years ago.
– Small marine organisms
– Continental drift and subsequent climate change

47
Q

Devonian extinction

A

365 million years ago.
– Tropical marine organisms
– Lack of oxygen in the oceans, quick cooling of air temperatures, volcanic
eruptions and/or meteor strikes

48
Q

Permian-triassic extinction

A

250 million years ago.
– Range of species, including vertebrates
– Cause unknown—possibly asteroid strikes, volcanic activity, climate change, and microbes
-The Permian extinction is linked to the effects of
extreme volcanic activity.

49
Q

Triassic-jurassic extinction

A

210 million years ago.
– other vertebrates; allowed dinosaurs to flourish
– Major volcanic activity with basalt flooding, global climate change, and changing pH and sea levels of the oceans

50
Q

Cretaceous-tertiary

A

65 Million Years Ago.
– Mass extinction of large land dinosaurs, allowed development of birds and mammals
– Extreme asteroid or meteor impact
-The Cretaceous extinction, which included most large
dinosaurs, caused by the impact of an asteroid.

51
Q

Adaptive radiations

A

periods of evolutionary change in which many new species evolve from a common ancestor.

52
Q

evolutionary developmental biology “Evo-devo”

A

combines evolutionary and developmental
biology.
-New forms can evolve by changes in the
number, sequences, or regulation of
developmental genes.

53
Q

Development of novel traits

A

complex structures may evolve in stages from simpler versions
with the same basic function
– or from the gradual adaptation of existing structures to new
functions.

Bio 100 (13 decks)

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