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Ecology - Evolution > Mechanisms - Genetic Conflict > Flashcards

Mechanisms - Genetic Conflict Flashcards

1
Q

How can evolution be thought of at the gene levle?

A

A gene enhance its own transmission relative to others, reducing transmission of other genes.

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2
Q

Genetic Conflict

A

This is the antagonistic interactions between DNA sequences or their products within an indivdiuals.

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3
Q

What may cause Genetic Conflict?

A

Meiotic Drive, Cytoplasmic Inheritance, post-segregation disorders and transposable elemnts.

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4
Q

What is an example of GC?

A

Thymes have hermaphroditic flowers whilst others lack anthers(male sterile) or just female.

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5
Q

What causes male sterility in thyme?

A

Cytoplasmic Male Sterility Factors allele in the mitochondria carried in all thyme.

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6
Q

How do hermpagroditic thyme bypass the CMSF?

A

Carry a restorer allele on nuclear chromosome counteracting it.

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7
Q

Why do some hermaphroditic plants carry both genes?

A

Mitochondria are only maternally inherited so any MC allele increasing number of females relative to males increase in frequency relative to one not altering the 1:1 sex ratio.

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8
Q

Why is excess female production disadvantageous to the nuclear genes?

A

Reduction of their transmission by pollen, allowing mutation nulling the effect of CMS to increase in frequency, counteracting the effects of the selfish gene.

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9
Q

How does the CMS gene create conflict?

A

The MC benefits from transmission of the CMS whilst nuclear genome benefits from production of functional mitochdndria.

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10
Q

When is fertility restored in thyme?

A

When a plant carries both CMS trait and suppressor alleles?

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11
Q

Meiotic Drive

A

This is the subversion of meioisis so that particular gene are preferentially transmitted to the progeny.

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12
Q

What is the basis of Meiotic Drive?

A

Two homologs have equal chance of being included in egg or sperm, meiotic drive increasing likelihood for one over the other.

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13
Q

What does meiotic drive result from?

A

Prefernetial segregation of genes disrupting other genes that lack it.

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14
Q

Where might meiotic drive be found?

A

Where progeny sex ratio depends on fertilization proportion of eggs by X/Y bearing-sperm yielding daughters and sons.

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15
Q

What are the mechanics for Meiotic Drive?

A

X-linked genes increasing proportion of successful X-bearing sperm distort sex ratio, increasing in frequency.

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16
Q

What would X-linked gene favourability lead to?

A

Selection of genes RESTORING 1:1 sex ratio to conceal the X-linked favouring gene.

17
Q

What is an example of Meitoic Drive?

A

Seychelles flies having segregation distorter gene on the X-chromosome causing male Y-bearing sperm degenration, with genes also supressing this distortion.

18
Q

What is an example of Meiotic Drive in mice?

A

T-Haploptype biases meiosis in favour of T-bearing sperm, thus in heterozygote offspring it can proliferate

19
Q

Why does fertility reduce in Mouse T-Haplotype?

A

Homozygous carriers by reducing spindle fibre chromosomal cell divsion, so homozygotes have abnormal sperm and eggs reducing fertility.

20
Q

What is an example of GC in TE?

A

Cause deleterious mutations and chromosomal rearrangments like in DNA methylation and INterference RNA reducing this.

21
Q

What is an example of offspring/parental genome conflict?

A

Mothers increasing insulin production in pregnancy

22
Q

Why do mothers increase insulin production?

A

Fetus produces high levels of hPL hormone counteracting insulin, with no alteration of mothers blood glucose concentrations.

23
Q

What is the conflict in the fetus?

A

Promote fetal grwoth whilst maternal genome maintain maternal health and avoid disease.

24
Q

Why does the mother increase insulin production from pancreas?

A

Maintain blood sugar levels as hPL increases demand from mothers body.

25
Q

What is the basis of P-O GC in genetic imprinting?

A

Some genes transcription in the embryo depends on whether they are inherited from the mother or the father.

26
Q

When would a paternal gene benefti?

A

If enhances embryo ability t obtain nourishment.

27
Q

When would maternal genes benefit?

A

Inherited genes tampering embryo ability to obtain nourishment

28
Q

Why would maternal gene benefit from tampering?

A

Improves genes ability to transmit even at expenditure of offspring fitness.

29
Q

When does paternal gene fitness have greatest genic selection?

A

If embryo survives as these genes are not carried by the mother if she mates with another male.

30
Q

Why are maternal genes benefical with tampering of nourishment?

A

Maternal transmitted genes carried by mothers subsequent offspring so inclusive fitness greatest if they prevent mother nurturing current embryo.

31
Q

How is GI seen in IGF-2?

A

Only paternal copy promotes early embryo nutrient acquistion from uterus
IGF-2 degraded by IGF-2r expressed only maternally, IGF-2 levels thus balanced by opposing effects of maternal by paternal genes.

32
Q

What is the principle of TE transmission?

A

Its capacity to replicate faster than the nuclear genome.

33
Q

What is an example of TE GC?

A

Endosymbiotic bacteria with human genome

34
Q

Why is excess endosymbiont growth prohibited?

A

Endosymbiont depends on resources of the host.

35
Q

Horizontal Transmission

A

This is the movement of the genom among indivviduals of the same generation.

36
Q

What does endosymbiont fitness depend on?

A

How many hosts it can infect per generation.

37
Q

Endosymbiosis in horizontal tranmission?

A

Number of new hosts infected proportional to number of stmbionts progeny released from each of old host.

38
Q

Endosymbiosis in vertical transmission?

A

This occurs from mother to daughter, entirely dependent on the host.

39
Q

What does group-level selection favour?

A

Restrained reproduction genoetypes to not lead to the host death by extraction of so many resources before progeny tranmisison

Ecology - Evolution (9 decks)

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