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Biology 1 > Evolution > Flashcards

Evolution Flashcards

1
Q

Gene pool

A
  • All copies of every type of allele at every locus in all members of population
  • If only one allele exists for a particular locus in a population, that allele is fixed in the gene pool
  • If at least 2 alleles for a particular locus exists, individuals can be heterozygous or homozygous
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2
Q

Fixed genes

A

All individuals in a population is homozygous for that allele

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3
Q

Allele frequency

A

Proportion in a population

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4
Q

Hardy-Weinberg equilibrium principle

A

Frequencies of alleles and genotypes in a population will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work

  • Only works if there is no natural selection
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5
Q

H-W equilibrium equation

A

p^2 + 2pq + q^2 =1

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6
Q

Conditions to be in H-W

A
  1. No mutations
  2. Random mating
  3. No natural selection
  4. Extremely large population size
  5. No gene flow
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7
Q

Natural selection

A
  • Individuals with certain traits tend to survive better in the wild
  • Non- random mating
  • Differential fertility
  • Environment
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8
Q

Genetic drift

A
  • Present especially in small populations
  • Chance events cause allele frequencies to fluctuate unpredictably from one generation to the other
  • Lead to loss of genetic diversity
  • Cause deleterious alleles to become fixed

ex. Some flowers get stepped on by a moose so they cannot produce offspring and their genes are lost

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9
Q

Types of genetic drift

A

1) Founder effect

2) Bottle neck effect

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10
Q

Founder effect

A
  • A few individuals isolated from a bigger population and start a population of their own
  • Gene pool of new population depend on the gene pool of the isolated individuals
  • Isolation must be by chance

ex. Storm, colonization,

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11
Q

Bottleneck effect

A
  • Size of population drastically reduced due to natural disaster or human action
  • Surviving population is no longer representative of original population
  • Has to be by chance
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12
Q

Gene flow

A
  • Transfer of alleles into or out of population due to movement of fertile individuals or their gametes
  • Reduces genetic differences between population and lead to two populations combining into one
  • May transfer alleles that improve ability of a population to adapt to local conditions
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13
Q

Evolution

A
  • Descent with modification
  • Living species are descendants of ancestral species that were different from the present-day ones
  • Also defined more narrowly as the change in the genetic composition of a population from generation to generation
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14
Q

Types of evolution

A
  1. Microevolution
    - Evolutionary change below the species level
  2. Macroevolution
    - Evolution change above the species level

Populations are the smallest unit of organism that can evolve, therefore, individuals cannot evolve

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15
Q

Adaptations

A

Inherited characteristics of organisms that enhance their survival and reproduction

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16
Q

Inferences

A

1) individuals whose inherited traits give them higher probability of surviving and reproducing tends to leave more offspring than other individuals
2) The unequal ability of individuals to survive and reproduce will lead to the accumulation of favourable traits in the population over generations

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17
Q

Homology

A

Similarity in characteristics resulting from a shared ancestry

18
Q

Artificial selection

A

Breeding controlled by humans to create a more favourable individual or species for consumption

19
Q

Divergent evolution

A
  • Population becomes separated from rest of the species
  • Different selection pressures and evolutionary patterns
  • The result of divergent evolution is homology
20
Q

Convergent evolution

A
  • Organisms occupy similar environments
  • Evolve similarities, but do not share a common ancestry
  • The result of convergent evolution is analogy
21
Q

Analogy

A

Similarity but not from common ancestry

22
Q

Cryptic colouration

A

Camouflage

23
Q

Aposematic colouration

A

Warning coloration

24
Q

Batesian mimicry

A
  • Harmless species mimics harmful species colour or physical traits
25
Q

Mullerian mimicry

A
  • 2 or more unpalatable or harmful species resemble each other to end a signal to potential predators that they cannot be eaten
26
Q

Relative fitness

A
  • Contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

types:

  1. directional
  2. disruptive
  3. stabilizing
27
Q

Directional Selection

A

Occurs when conditions favour individuals exhibiting one extreme of a phenotypic range

28
Q

Disruptive Selection

A

Occurs when conditions favour individuals at both extremes of a phenotypic range

29
Q

Stabilizing Slection

A

Acts against both extreme phenotypes and favours intermediate variants

Reduces variation

30
Q

Speciation

A

Process by which one species split into 2 species

31
Q

Biological species concept

A

Group of populations whose members have the potential to interbreed in nature to produce viable and fertile offspring

32
Q

Reproductive isolation

A
  • Existence of biological factors that impede members of 2 species from interbreeding and producing viable and fertile offspring
  • Barriers may be pre-zygotic (block fertilization) or post-zygotic (reproductive isolation after hybrid is formed)
33
Q

Pre-zygotic barriers

A

Habitat isolation:
- Two species occupy different habitats in same area encounter one other

Temporal isolations:
- Species breed during different times of day/years/seasons

Behavioural isolation:
- Coutship rituals and other behaviours may be unique to species so they cannot recognize each other as potential mates

Mechanical isolation:
- Morphological differences prevent mating from completing

Gamteic isolation
- Sperm of one species may not be able to fertilize egg of another species (sperm may not survive in reproductive tract of female OR sperm cannot penetrate membrane surrounding egg)

34
Q

Post-zygotic barriers

A

Reduced hybrid viability:
- Hybrids may not develop completely or are very frail

Reduced hybrid fertility:
- Hybrid may survive well, but is sterile and cannot produce gametes

Hybrid breakdown:
- First generation hybrid may be viable and fertile but when hybrids mate with each other or with either parent species, next generation is frail or sterile

35
Q

Causes of speciation

A
  • Allopatric

- Sympatric

36
Q

Allopatric

A
  • Gene flow interrupted when populations are isolated geographically
37
Q

Sympatric

A

Occurs in populations that live in same geographic area

Types:

  • Poluploidy
  • Habitat differentiation
  • Sexual selection
38
Q

Polyploidy

A
  • Accident during cell division that results in extra sets of chromosomes
  • More common in plants than animal
39
Q

Habitat differentiation

A
  • Genetic factors enable subpopulation to exploit habitat or ressources not used by parent population
40
Q

Sexual selection

A

2 closely related sympatric species differ mainly in colour breeding males

Biology 1 (11 decks)

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