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Biology 3051 & 3052 SPECIATION > BIO 3052 EVOLUTION PROCESSES > Flashcards

BIO 3052 EVOLUTION PROCESSES Flashcards

1
Q

Species

A
  • transcend time, not populations or individuals
  • a group of actually, or potentially, interbreeding natural populations that are reproductively isolated from other such groups
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2
Q

Hybrids

A

The result of a cross between individuals of two different species or subspecies

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3
Q

Population

A

Refers to individuals of the same species living in a particular area and sharing the same gene pool

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4
Q

Gene pool

A

All alleles of a gene within a population

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5
Q

Crossing over

A

The exchange of genetic material between homologous chromosomes

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6
Q

Inheritance

A

Characteristics that pass from one generation to the next

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7
Q

Interbreeding

A

Each individual that lives in a species carries a unique combination of genotypes, and every time sexual reproduction takes place, there is a mixing of genetic material. Interbreeding means exchanging genetic material (species context)

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8
Q

Give examples of hybrids

A

-crosses between two closely related species
-dog with dingo, grey wolf, coyote
-rarer for animals and a product of circumstance, eg, no other potential mates nearby or being held captive
-often, (plants & animals) hybrids may be sterile which means genes will be lost from gene pool when they die

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9
Q

Ring species

A

-type of cline

-connected series of neighboring populations, each of which can interbreed with closely sited populations, but no interbreeding occurs anymore between individuals from the two ‘ends of the ring’

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10
Q

Cryptic species

A

-Morphology of individuals is very similar or identical, so they look alike but no inbreeding.
-Gene pools are not shared so dealing with different species
-When analysing DNA, conclude that there was only one species.
-CRYPTIC SPECIES (hidden or obscure)

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11
Q

Explanations of cryptic species

A

Speciation has already broken down interbreeding but not enough time has passed for this to have become apparent as different phenotypes.

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12
Q

Deme

A

Local population that can interbreed with another population and therefore share the same gene pool

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13
Q

Speciation

A

Formation of new species

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14
Q

Gene pool of large Māhoe population.

A
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15
Q

North and South island saddlebacks
Barriers to interbreeding :

A
  • Geographic : North island vs South island
  • Different calls
  • Different plumage
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16
Q

Hector’s and Māui’s dolphins
Barriers to interbreeding :

A
  • Geographic : North island vs South island
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17
Q

Barriers to interbreeding

A

-pre-zygotic barriers (favoured over) & could be a key factor in stopping interbreeding between different species
-post1zygotic barriers

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18
Q

Pre-zygotic barriers

A

-Habitat isolation : organisms within a population become physically seperated

-Temporal isolation : being active at different times of the day, breeding at different times of the year

-Behavioural isolation : like courtship behaviour in birds, songs and calls, beak size, brightest plumage ( if anything is not right mating will not occur)

-Mechanical isolation : incompatibility of sexual organs prevents mating

-Gametic isolation : gametes of one individual do not survive inside the body of the other individual, or gametes fail to fuse properly

-Geographic isolation : isolation where there are physical barriers between closely related species such as mountains, rivers, the sea or altitude

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19
Q

Post-zygotic barriers

A

-Reduced hybrid viability : hybrids form but die (offspring die young or does not develop)

-Reduced hybrid fertility : hybrids form but are sterile

-Hybrid breakdown : hybrids may be fertile and reproduce successfully, but then their offspring are either infertile or they die young

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20
Q

Geographic isolation

A

•Physical barriers such as mountains, rivers, sea and altitude- important driver of speciation
•distinguis between sympatric speciation and allopatric speciation
•Speciation occurs because because of demes becoming geographically isolated.

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21
Q

Sympatric speciation

A

-two seperate species form from one species in the same place
-arise when vacant niches in habitat can be exploited as selected from different alleles in parents population.
-seasonal, behavioural, and mechanical isolation are most likely causes

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22
Q

Allopatric speciation

A

When populations of one species become isolated from each other and change into seperate species over time

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23
Q

Allele frequency

A

Proportion of all copies of a gene being of a particular type/version

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24
Q

What does loss of alleles mean

A

Loss of alleles means loss of genetic variation.
Can affect long-term survival chances that a population and species might have

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25
Q

Hardy-Weinberg equilibrium

A

The allele frequencies of the dominant and recessive alleles of any particular gene, remain the same from one generation to the next. It implies that there is no preference for, and no selection towards any allele.

Put to use in medical genetics and efforts to conserve biodiversity.

26
Q

Hardy-Weinberg equilibrium can only be upheld if

A

-large population size
-mating is random
-no natural selection
-no mutations
-isolated population

27
Q

What will happen if the Hardy-Weinberg equilibrium is maintained

A

-population will not evolve
-no allele is favored over any other

28
Q

Explain recombination in short

A

It brongs together new allele combinations which increases genetic variation in offspring.
Sexual reproduction is thereby helping to maintain or enhance genetic variation.

29
Q

What does fertilization mean as it re-establishes cells with homologous pairs

A

Alleles have a history, they have continuity over time whereas genotypes do not have continuity, they fall apart as a result of meiosis

30
Q

Why does non-disjuntion take place

A

Because the spindle fibres did not form or function properly.
Result in gametes containing the full set of chromosomes.
If two such gametes fused, result would be a zygote with double numbers of chromosomes compared to either parents.

31
Q

Polyploidy might help with…

A

Survival in habitats with greater environmental extremes such as temperature fluctuations in higher altitude regions. Far more common in plants

Can be responsible for instant speciation

32
Q

Polyploidy is caused by…

A

…non-disjunction of chromosomes to their advantage. They do this by exposing plant cells to chemicalsthat prevent the formation of these spindle fibres

33
Q

How can speciation occur

A

Polyploidy can be responsible for instant speciation
Allopolyploidy and autopolyploidy are ways in which speciation can occur

34
Q

Gove one way through which alleles are shared between and within gene pools

A

Sexual reproduction is one way through which alleles are shared between and within gene pools

35
Q

Mutations

A

Unrepaired change to the sequence of bases in the DNA
It introduce new alleles into the gene pool

36
Q

Explain in more depth, mutations

A

Mutations are random unrepaired changes to the sequences of bases in DNA. It adds genetic variation to the gene pool by creating new alleles.
Mutation, combined with natural selection, increases genetic variation and therefore the evolutionary potential of species. It is a potent evolutionary force.

37
Q

Explain mutations combined with natural selection

A

It is a potent evolutionary force. This is because mutations provide new sources of genetic variation, and natural selection provides the selection pressure which determines the resulting allele frequencies. It is genetic variation that allows evolution to take place

38
Q

How does mutations happen

A

Mutations happen randomly caused by mutagens such as high energy radiation, chemicals and viruses. They can affect one gene of the whole chromosome.

39
Q

Neutral mutations

A

Have no effect on the individuals phenotype

40
Q

Harmful mutations

A

Has harmful effect and cause organism to stand out clearly in its habitat. This means that predators can easily spot these individuals so chances for survival to breeding age are limited. No offspring means alleles and mutations will be lost from the gene pool

41
Q

Examples of harmful mutations

A

Humans :
- huntingtons disease
- cystic fibrosis
- muscular dystrophy

Animals :
- naked mouse
- white kiwi chick

42
Q

Natural selection can be

A

Stabilising
Directional
Disruptive

43
Q

Why is natural selection important, elaborate

A

-It is an important driving force of evolution
-It favours certain alleles over others
-Implies that the resulting allele frequencies reflect an adaptive advantage.
-It can change the allele frequencies of a gene : preferential survival of offspring

44
Q

How are certain individuals favored in natural selection

A

Changes in the environment could favour individuals with particular phenotypes, which in turn are a refelction of underlying allele combinations (genotype). These favored individuals would then be more likely to pass on their characteristics (alleles) to successive generations

45
Q

Natural selection definition

A

The process by which organisms that are better adapted to their environment can survive and produce more offspring than less well adapted individuals. It is not random and the diversity of life is not just a random stroke of luck. Certain genotypes could be favored.

46
Q

Selection pressure

A

The environment in which individuals live exerts a selection pressure. Intensity and direction of pressure can vary in time and space.

47
Q

Three types of selection operating in a population

A

Stabilising
Directional
Disruptive

48
Q

Give evidence in support of natural selection

A

-Natural selection provides a way in which allele frequencies can change in a population.
-With natural selection a change in allele frequency reflects and adaptive advantage.
-End result of disruptive selection could be formation of two demes
-two demes could still interbreed, each deme would show clear genetically determined different phenotypes. (Polymorphism)

49
Q

Immigration can increase …

A

… genetic variation

50
Q

Emigration could mean…

A

… reduction of genetic variation

51
Q

Explain genetic drift

A

It is the result of chance events having an impact, which is greatest in small populations.
It is not a result of natural selection, instead it reflects a population’s life history rather than evolution.

52
Q

What does the founder and bottleneck effect have in common?

A

Both refer to a small number of individuals alive to carry on the new or existing population.

53
Q

Explain gene flow

A

Gene flow among populations is a cohesive force that maintains the connectedness between seperated populations. This ensures that all populations remain a single species.
In small populations chance events can start to effect the allele frequencies of genes in this gene pool (genetic drift)

54
Q

Explain genetic drift

A

It implies that the allele frequencies can change abruptly from one generation to the next.

55
Q

Compare gene flow with genetic drift

A

Gene flow maintains genetic homogeneity and genetic drift can cause demes to become genetically distinct.

56
Q

Explain the founder effect

A

It refers to potentially having a limited representation of all the alleles in a gene pool because only a small number of individuals have established a new population .

57
Q

Explain bottleneck effect

A

Reduction in variety of alleles in a population is when the population suddenly loses many of its members.
Can be caused by natural disasters, habitat destruction, overexploitation, or introduced predators.

58
Q

Relationship between bottleneck and founder effect

A

Both are moments in time when there are only a few individuals representing the alleles held within the gene pool.

59
Q

Explain evolution

A

It has led to an incredible level of biodiversity.
Evolution is a process that happened in the past and is taking place right now and shaping our future biodiversity.

60
Q

What is maintaining biodiversity about

A

It is about preventing the extinction of species and their genetic diversity. Species survival does not only rely on the number of individuals (population size).

Maintaining the highest level of genetic diversity (allelic diversity) within a species provides it the greatest chance to evolve in response to environmental change.

Large genetically connected populations will be invariably more stable than small isolated populations

Biology 3051 & 3052 SPECIATION (5 decks)

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