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Evolution and Behaviour > Lectures 1-3 > Flashcards

Lectures 1-3 Flashcards

1
Q

Lab Work using captive Great tits

A
  • Nikolaas Tinbergen
  • 1974
  • meal worms between two patterns on a light box
  • Meal worms represent the body of flying insects—>most can survive without sections of wings
  • Great tit startled when light box turned on and the patterned flashed
  • Unclear if it is the pattern, colour or the sudden presence of them that caused startling
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2
Q

Cause of eyespots

A

How?

  • specialised hairs that look like scales
  • some iridescent

Why?
- defend against predators/startle them or even to redirect where attack is most likely to be

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3
Q

Ultimate reason for adaptation

A

Adaptive value of the adaptation

why is it more likely to survive and reproduce with this trait

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4
Q

Historical background of Evolution

  • who x2
  • when together
  • what published
  • Inspiration
A

Darwin and Wallace
then presentation of both works to linnean society
roughly a year later
Origin of species in 1859
but 1837 was when first evidence of evolutionary trees in notebooks
spent much time gathering evidence—>including Beagle voyage

Inspiration came from Malthus=economist
population growth increase then so does strain on resources
Darwin said it works for natural world
The ones that died before reproducing was not random

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5
Q

Definition of natural selection

- before and after modern synthesis

A

Before=
- the differential survival and reproduction of individuals with favourable traits

After=
- differential survival of alternative alleles

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6
Q

3 conditions necessary for natural selection

-include definitions before and after modern synthesis

A

Heredity

  • Before=Individuals resemble parents
  • After=Genes replicated and passed onto offspring

Variation

  • Before=Individuals vary in their characteristics
  • After=within population many genes occur in multiple alternative forms=alleles

Fitness Differences

  • Before=relationship between the characteristic possessed and the individuals ability to survive—>its fitness
  • After=different alleles have differential effect on fitness—>individuals ability to survive and reproduce
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7
Q

Why doesn’t blending genetics model work

- what is this theory mainly associated with

A

No matter how advantageous or favourable the trait it is rapidly lost/diluted when individuals mate with other members of population
- generally associated with Lamarckism where the body must be copied generation to generation

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8
Q

When did the modern synthesis occur

A

The rediscovery of Mendel’s work in 1900
Mainly incorporated with evolution 1940-1950
- gave the method of inheritance as fundamental units of information passed on
- mendelian genetics gives reasons for rise in allele (characteristic) frequencies rather than a dilution of them
- Conclusion that the body is only the carrier and representative of its genes

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9
Q

Natural Selection on Molecules

  • Name
  • Overview of experiment
A
  • ribozyme of protozoan Tetrahymena
  • ribozyme remains attached to substrate for a time
  • found successful ribozymes by removing those attached to the substrate and copying them
  • normally catalysed on medium with Mg2+ ions
  • changed to Ca2+ ions and over 12 generations with only the ribozymes that carried out the catalysation selected for—>almost to the rate of that in Mg2+ ions
  • 7 substitution event
  • variation in original structure so natural selection on molecules
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10
Q

Evidence of natural selection in the wild

- Peter and Rosemary Grant

A
  • Daphne island in Galapagos
  • almost all Medium ground finch recorded with multiple measurements—>but most importantly=beak size
  • drought between 1976-1978
  • beak size increased
  • drought killed plants and small seeds went first so larger seeds left
  • birds with larger beaks could eat the food left
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11
Q

Origin of variation

A

mutation

- mutation is random but the selection of them isn’t

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12
Q

Genetic Drift

- plus 2 examples

A

changes in allele frequency caused by chance rather than by natural selection

  • founder effect= population founded by a small number of individuals will have a fraction of the diversity of the large parental population
  • bottleneck effect=a lot of the population dies off suddenly and the population goes through a period of low numbers before expanding again
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13
Q

Why did darwin have a problem with small increment changes

-give example explaining why he didnt need to

A

Each change would have to be advantageous, not just the final structure as there is no foresight in evolution

  • for example the eye
  • evolved twice, vertebrate and mollusc eyes
  • also species existing with the separate stages required to develop a complex eye and each are adapted to their environments
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14
Q

Study that showed that a computer can evolve the eye

A
  • 1% changes in anatomy/structure of the eye as well as other parameters to allow for relatively accurate natural selection pressures
  • like they have to be advantageous
  • the computer programme gave a fully evolved eye in juts 100,000 years
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15
Q

two categories of evolution

A

asexual and sexual

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16
Q

Types of sexual reproduction

A
  1. Isogamy- Where the gametes are the same size
  2. Anisogamy- The gametes are different sizes depending on sex and usually the female is one large but males is many small.
    Sexual reproduction is meiosis
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17
Q

Types of asexual reproduction

A
  1. budding
  2. fission
  3. runners
  4. parthenogenesis
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18
Q

Earliest known sexually reproducing organisms

A

Red alga roughly 1.2 billion years ago.

Known because they share many characteristics with red alga that sexually reproduce in present day

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19
Q

Different types of sexual lifetime cycles

A
  • haplontic life cycle-where dominant is haploid
  • diplontic - dominant is diploid (humans)
  • haploid-diploid life cycle—>all plants where both diploid and haploid parts are multicellular
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20
Q

How could anisogamy evolved from isogamy and what does this predict about the number of sexes

A

Gametes were originally the same size and then two selection pressures arose
1. Numerical productivity
2. Zygote fitness
So division into small number of large gametes (eggs for females) and large number of small gametes (sperm for males)
This suggests why there are typically two sexes as there is only the evolutionary advantage for two different types as an intermediate would not be advantageous

21
Q

The two-fold cost of sex

A

males make little to no contribution. Only genetic material not individuals when sexually reproducing and so females ‘waste’ half their individuals producing males which do not contribute. However, asexual individuals can give double to grandoffspring.

22
Q

What are the two reasons why sex has evolved

A
  1. sex can speed up evolution
    - favourable mutations can be combined horizontally through population—>horizontal gene transfer.
    - asexual reproduction is linear and so combinations of mutation occur over a longer time period
  2. Sex allows deleterious mutations to be weeded out
    - MULLER’S RATCHET
    - asexual lineages can only remove bad mutations through back mutations and so can have multiple deleterious mutations over time

GRAPH

23
Q

parthenogenetic taxa

A

secondarily asexual
are rare and have patchy distribution across phylogenetic trees and are usually at the tips which suggests that they are not able to persist for long evolutionary time
EXCEPTION- order Bdelloidea

24
Q

Problems with the group-level ideas for the evolution of sex are?
x2

A
  1. rely on the rates of asexual reproduction arising in populations being very low
  2. facultatively asexual species—>different points in their lifecycle they switch between sexual and asexual reproduction
25
Q

Red Queen model of sex

A

sex provides an advantage for individuals
- ecological arms races such as
1. predators and prey
2. parasites and hosts
3. males and females
constant change required and so advantageous to be different from parents

26
Q

Example of red queen model

A

Fresh water snail species Potamopyrgus antipodarium
sexual and asexual population in multiple different lakes and there is a correlation between the higher levels of parasites present and increased levels of sexually reproducing individuals

27
Q

How have Bdelloid rotifers stay asexual with their fungal pathogens present

A

They cannot escape by continual coevolved gene shuffling and so they completely desiccate and disperse as tiny propagules to establish new populations

28
Q

Why are the majority of species in a sex ratio of 1:1?

A

Apart from the fact that it might be because of mechanistic constraint such as XY sex determination

  • only evolutionarily stable sex ratio
  • as the population becomes more biased to a sex the opposite sex will become more successful in having grandoffspring and so the selection will be against the bias and then vice versa once the sex that previously had less numbers has higher occurance
29
Q

Why is it generally males that seek out and compete for access to females

include two exceptions

A

because the sex that has the greater potential reproductive rate, which is usually males, will be under strong selection to seek out and compete for access to the other sex, usually females.
The sex that makes a bigger investment in the gametes/young will be expected to be more choosy.
Exceptions-
1. Kittimake gull- monogamous and so no specific choosy behaviour
2. Pipefish where females have a greater maximum offspring number during their lifetime as the males are the main egg guarders

30
Q

The two interactions that cause differing strategies for maximising lifetime success

A
  1. male-male fighting

2. female choosiness

31
Q

Male-male fighting

x3 main

A
  1. physical fighting and therefore development of defences—>antlers or horns
  2. Sperm competition—>some males remove sperm of previous matings—>dragonflies
  3. Mate guarding after sex
32
Q

Female choice

A
  1. Direct benefits such as food or evidence of caring father (if the male is involved in offspring development)
    EXAMPLE- Nursery web spider presents nuptial gifts and the larger the gift the longer mating
    Also if female is starving and the male does not have a gift then the female will eat him
  2. May choose for certain traits which have 2 main reasons
    a) Indicator mechanisms/ handicap principle where the ornaments indicate vitality and stronger males and therefore stronger offspring
    b)Fisherian or runaway selection where the female preference for the trait is passed on with the male trait and so the females become more choosy and so the males match that choosiness.
    THESE ARE NOT MUTUALLY EXCLUSIVE
33
Q

Example of indicator mechanisms

A

Male Great tits with larger stripes are more likely to survive the winter (Norris, 1993)
- And this association was seen with biological father rather than their foster fathers and therefore it was definitely a genetic advantage

34
Q

What determines which traits are first used in mate choice?

x1 and example

A
  1. sensory bias for particular traits or signals—>like they look like a food
    Australian grass finches where they added crests of different colours and white crests were favoured over no crests and those of different colours.
35
Q

How can natural selection explain male lions killing infants

A

Research shows that infanticide levels rise after a pride has been taken by a new male. By killing the existing cubs, not only does it reduce competition for his own offspring but gets the females ready to bear young much more quickly

36
Q

Why do we have a recurrent laryngeal nerve

A

Loops under the aorta due to the fact that the neck has elongated and the heart set back from when we were fish

37
Q

What are the advantages of cooperation?

x 7

A
  1. Dilution effect
  2. Increased vigilance
  3. Confusion effect
  4. Shared defence
  5. Group hunting
  6. Shared information
  7. Shared body heat
38
Q

Why does apparent altruism present a paradox?

A

Natural selection would not select for behaviour that improved the reproductive rates of others if it caused a loss in reproductive success within the actor

39
Q

The two hypothesises for altruism

A
  1. Group Selection

2. Kin Selection

40
Q

What is the group selection hypothesis

A

The altruistic behaviours increase the reproductive success of the group overall. e.g. smaller litter sizes would mean that the resources would not be outstripped
HOWEVER—> requires many parameters including isolation from other populations as moving can encourage selfish behaviours

41
Q

Kin Selection

A

Altruism can occur provided the actor and recipient share genes. So they are related and therefore the genes associated with this behaviour get passed on

42
Q

What is inclusive fitness

A

Helping close relatives to reproduce in order to pass on genes through them. In 1:1 sex ratio, diploid populations, you are equally related to your siblings and offspring

43
Q

Hamilton’s Rule

A

(r2/r1)b - c > 0

where:

r1=relatedness of the altruist to the beneficiary’s offspring
r2=relatedness of altruist to its own young
b= benefit, increase in B’s young due to altruism
c= cost, so the decrease in A’s young due to its actions in helping B

44
Q

Relatedness (r) (and how to calculate it)

A

The probability that a genes in one individual is an identical copy, by decent, of a gene in another individual
- to calculate this draw out a pedigree In diploid populations this is usually 0.5 fro each step. Total this to get r

45
Q

Carpenter Bee example

A

Example of faculative altruism
- The chance that the daughters will stay to help guard their siblings depends on how likely they are to keep their own nest

46
Q

What is the extended phenotype?

A

May be functionally important consequences of gene differences outside the body in which the gene sits.

47
Q

an example of extended phenotype

A
  1. Cuckoo

- manipulates host by laying eggs that resemble those of the host bird. Young also mimic calls of multiple young

48
Q

Explanation and example of constraints on adaptation

A

Natural selection does not start from scratch and so there are multiple examples of ‘imperfect design’

Example: the vertebrate eye has to have a blind spot because the photoreceptor nerves come from the retina side of the receptors. However, mollusc eyes do not have this problem and are ‘wired the right way’ so no blind spot

Evolution and Behaviour (8 decks)

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