MT Animal Behaviour Flashcards
1
Q
what are the 4 proximate and ultimate strategies underpinning animal behaviour
A
proximate (causal): mechanism and developmental
* what physiological signals drive one behaviour over another
* developmental: how does this behaviour develope? innate or learnt
Ultimate (evolution):
* adaptation/function: how does this behaviour affect fitness
* phylogeny: what is this role in phylogeny
2
Q
what are cues, what are signals? what are the differences between the two?
A
- Cues: When the receiver uses some feature of the sender to guide their behaviour, but this fearture has not evolved for that purpose.
* E.g: A cue such as carbon dioxide released by a mammal. This CO2 acts as a cue to mosquitoes indicating presence of source of blood from mammals. However, the mammal did not produce CO2 in order to signal their blood presence to mosquitoes, as they would rather not get bitten - Signals: acts or structures produced by sender that alters the behaviour of the receriver. They evolved because of that effect and are effective because the receiver’s response to that signal also evolved.
3
Q
Define signal, and its 2 consequences
A
- A signal is an act or structure that alters the behaviour of another organism, which evolved because of that effect and which is effective because the receiver’s response has also evolved.
Has 2 important consequences:
1. The receiver has to be evolved to respond to signal. Hence for a respose to be evolved, the response must be ‘on average’ beneficial to receiver. On average because sometime dishonest signals evolve to produce deceptive signals, which exploit the honest signalling of others.
2. 2nd consequence: the signal it evolved must evolve independently of the feature they carry information about.
4
Q
what is an example of the 2nd consequence of signalling?
A
- 2nd consequence: signals must be able to evolve independently of the feature they carry information about
- E.g: Funnel Web spiders differed in weights. Research found that smaller spiders retreated rather than fighting over attack site
- this is NOT because spiders can self assess and judge the weight of other spiders, so that larger spiders with better fighting ability would fight
- But because an INDEPENDENT signalling method evolved. Which is the spiders would all signal their size by vibrating the web
- the signal here ‘vibrating web’ evolved independently, as vibrating the web is irrespective of their weight.
5
Q
what is the problem with signal reliability?
A
- using an example such as sexual conflict and sexual selection
- indian peafown choose to mate with the males which have the most eyespot on their tail
- the numner of eyespot is a reliable signal of genetic quality of males.
- Why don’t males deceive and trick females into mating with them by producing more eyespots on their tail.
- that is the problem with dishonesty, animals selfishness should prioritise themselves and produce deceitful signalling, but why don’t they?
6
Q
3 possibilities to solve signal reliability
A
- an index signal: a signal that cannot be faked. Size of tail is constrained by size of male. Hence poor quality males just are not big enough to carry more eyespot
- Handicap signal: a costly signal to fake. Poor quality males can produce fake signals and extra eyespots, but this would be very costly. They would have to take resources from elsewhere to invest in these eyespots. If they reallocate investment into immune system into eyespots, this may cause them to die quicker sue to more likelihood of severe infection.
- signalling can be honest if the sender and receiver have same interest (common interest signals): i.e male and female more both interested in male eyespot as it could mean that they are more genetically matched.
7
Q
summary of 3 possible reasons to ensure honest signalling
A
- Index: dishonesty is not possible
- handicap: dishonesty is too costly
- common interest: dishonesty is possible, but unprofitable to both sender and receiver
8
Q
What are the common indices signal/cues?
A
- used in fightingindividuals use a sequence of various displays to assess each other’s fighting ability
- where poor quality individual backs of rather than fights
- these are indices signals as they cannot be faked
9
Q
what is an example of indices signalling? Please be detailed
A
- in red deer stags: males compete for females
- a male’s fighting ability is related to its reproductive ability: better fighting ability = stronger more likely to survive offsprings
- males won’t actually fight with each other as this is severely harmful and causes injuries
- hence they assess each other’s fighting ability by roaring signals, and if the roaring signals turned out to be equal, then they would fight
- Red deers used format frequency to signal stag’s body sizes
- Bigger and larger body deers would have lower frequency roars
- frequency of roar is constrained by their body size
- this frequency does cause receiver to respond as well, as they would roar back with a lowered roar to make themselves sound bigger/
- Also lower freq roars fif attract females more
10
Q
what is sequenial assessment in indices signalling/fighting?
A
- would carry out multiple repeats of indices signalling to help receiver better assess signal of fighting
- much like statistical sampling, to increase sample size to decide and assess more accurately the fighting ability of others
11
Q
How did lower roar frequencies evolve in red deers?
A
- red deers produce roars which have a much lower freq than other mammals and females
- this is supposed that in evolutionary history: a male deer evolved ability to roar at lower freq than others, and hence showed a reproductive advantage by producting a ‘dishonest’ signal
- However, this indices signal then slowly spread and fixated due to its huge advantage
12
Q
How can extravagent signals be favored by natural selection: such as the costly extravagent feathers on male peacocks
A
- displayed favored because they are costly, which makes them reliable
- Alan Grafen showed handicap principle of natural selection would only work if the fitness cost of producting the costly signal is more costly to lower quality individuals than higher wuality individuals?
- Both high and low quality individuals can produce these costly signals, but it would be extremely more costly for lower quality individuals, and this cost would outweigh the benefits it brings
- whereas, altho still costly for high qualuty individuals, the benefit it brings outweighs the cost
13
Q
What is the difference between handicap signals and indices
A
has a strong condition dependence* in handicap signals: has a strong condition dependence: if strong quality males = facoured to produce strong quality signals. high quality individuals shoudl be favored to produce the signal, whereas low quality individuals should not
* indices is much more varied and gradual with quality, indices signal HAS to occur, but the quality of the signal is what differs and defines individuals
14
Q
what is an example of handicap?
A
- in stalk eyed flies
- males with wider eye span are chosen more by females
- when given less food, flies decreased significantly more in eye span, than any other body feature in males
- hence concluded that high quality males allocate more resources to sexual signal of eye span
15
Q
what is another cost of faking quality or status signals
A
- sometimes handicap signals of quality are not costly and easy to produces
- such as in certain bird species
- dominant birds with a ‘badge of status’ had better food supplies, these badges of status is not costly to produce, so why dont subordinates produce them too?
- this is because there is a SOCIAL cost in doing so
- punishement and increased agression is what stops them form producing dishonest signals
16
Q
what are the costs of handicap, common interest, and index?
A
- all split into efficacy costs and strategic costs
- efficiacy cost: is the cost that ensures the signal is reliably received by the receiver. Such as energy produced in roars in red deer (indices)
- strategic costs: applies more to handicap, it is the cost required to maintain the honesty of a handicap signal - this often is about the content: how much cost are you going to strategically put in to signal your content?
- all forms of signals have efficacy cost, but the cost varies.
- ONLY handicaps have a strategic cost
17
Q
what is an example of common interest
A
- waggle dance in honeybees
- performs waggle dance to communicate and signal other workers where the food source is
- the common interest here is because of kin selection
- similarly in quorem sensing of bacteria. Bacteria produce signalling molecules or exoproduct released into environment to benefit other bacterial cells from growth and ability to attack host
- cooperation between bacterial cells is due to kin selection, especially in a higher density cell culture as it allows nutrients to be used by neighbouring and related bacterial cells before dispersing
- other examples include alarm calls by meerkats which is a type of altriusm and kin selection showing common interest
18
Q
how is dishonestly avoided in human language?
A
- honesty in human labnguage is maintained by social cost of lying and common interest
19
Q
what is a dishonest signal?
A
- a dishonest signal is when the sender does something that manipulares the behaviour of the receiver to benefit the sender and detriment the receiver
20
Q
what are some questions about dishonest signalling
A
- is the balance between dishonest and hosnest signal an equillibirum, or is the signalling system breaking down
- and if its a stable equillibirum, then what prevents dishonest signals spreading?
21
Q
what is an example of dishonest signalling and how is it prevented or kept as an ESS?
A
- In Drongos, they make deceptive alarm calls to the meerkats
- this causes meerkats to flee and leave the food, for drongos to steal
- meerkats are responsive to this deceptive call as there is no difference in the type of alarm call drongos make between true and false calls
- however, this false alarm call doesn’t occur all the time, but if the meerkats ignores a true alarm call, the cost is huge
- however, meerkats also evolved against this type of dishonesty by less likely to flee when drongos make an alarm call and predators are absent
- meerkats also judge and observe predators for themselves instead of only relying on drongos alarm calls
- hence dishonest signals only maintained if occurs at a low frequency, or if the cost of ignoring a true signal outweighs the cost of responding to a fake signal
22
Q
what is economy of effort in signalling
A
- allows signals their effect without direct force
- i.e instead of figthing red deer stags will roar to symbolize their physical strength
23
Q
what are the 4 problem and solution when it comes to experimental design for animal signalling?
A
- problems:
1. background noise
2. signal degredation
3. confusion with other signals
4. correct recognition of response - Solution
1. Conspicuousness
2. repetition and redundancy
3. stereoptype and distinctiveness
4. intensity
24
Q
what are 3 properties which contribute to a signal’s efficacy?
A
- detectability: is it easy to detect
- discriminability: its difference to other signals
- memorability
25
Q
what is the red queen hypothesis of evolution
A
- the non ending continuous run of evolutionary arms race
- where predator and prey or host and parasite keep evolving as a response to each others evolutionary adaptations to ensure they can keep up with their rivals
26
Q
what are some examples of predator prey adaptation and counter adaptations
A
*
27
Q
what are 2 questions important in predator prey interactions
A
- ensuring that our hypothesis about adaptation counter-adaptation are verified by experiment testing and not just storytelling
- how does an arms race begin?
28
Q
what is crypsis
A
- The ability of an organism to conceal itself especially from a predator by having a color, pattern, and shape that allows it to blend into the surrounding environment.
29
Q
what is aposematism
A
the use of warning coloration to inform potential predators that an animal is poisonous, venomous, or otherwise dangerous.
30
Q
what is an examples of crypsis?
A
- an experiment where they showed blue jays slides which either had a moth, or didnt have a moth
- the background of the slide were either crypsis of conspicuous
- and the blue jays were taught in advance to peck on a key if they think no moth is present, ot pecking at the slide when they think a moth is present and rewarded a worm
- when the blue jay made a mistake: either pecked at the slide when no moth is present or pecked at the key when a moth is present, blue jay is punished
- results showed that blue jay made more mistakes when moth was presented on a cryptic background rather than a conspicuous background
- this provides supporting evidence about crypsis in that it may help preys avoid predation via camouflage
31
Q
what is a ‘search image’
A
- it is when the predator improves its ability to see cryptic preys over time via a process called ‘adopting a specific searching image’
- experiment on domestic chick pecking on rice grains mixed with cryptic stone grains showed an improvement in accurately finding rice grains over time
- and a better eye for finding cryptic prey/food
32
Q
what is polymorphic cryptic colouration?
A
- it is when the rarer phenotype due to polymorphism cryptic colouration is the most advantage
- this causes apostatic selection: where individuals of rare prey morphs were more likely to be overlooked
- preys which had a rarer morph would not be identified easily by predators as they are not within their ‘image searching process’
- causes a disruptive selection of common phenotypes and maintains multiple phenotypes in population
33
Q
what is the ‘sartle effect’ ?
A
- the existence of brightly coloured wings or signals to warn off predators
- example is jays which are trained by grey colored hindwing moths were startled and slightly delayed in their attack when then exposed to brightly colored hindwings of moths. But did not startle when the other way around, showing bridght colors startled and delayed attack time of jays
34
Q
what is an example of perception instead of mimicry?
A
- butterflies have eye spots on their wings, which expose when disturbed, causing predator to cease in attack
- experiments of peacock butterflies show that birds are more likely to attack butterflies which have thei eyespots covered than when they are exposed
- this is NOT because these butterflies are untastefukl
- THIS IS ALSO NOT BECAUSE: eyespots mimic the eyes of predator’s enemies such as owls
- an experiment which used artificial moths (mimicked by worms w paper wings) showed that there was no significant change in a bird’s predation when they had bars compared to when they had eye-shaped wing spots
- this showed that eyespots worked simply to alert the predator that the prey is aware of the predator
35
Q
what is an experiment which shows how camouflage and counter-adaptations ocurred initially?
A
- experiment showed that even a slight concealment/camouflage to begin with provided a very large benefit and advantage to preys
- great tits were presented with 3 options of food: an inedible twig in an opaque glass (to mimic the large edible cryptic prey); a large worm in an opaque glass; and an easily distinguishable short worm in clear glass.
- the great tits chose the more easily distinguished short worm to maximize rate of energy intake; instead of spending a few seconds more to distinguish between the 2 larger worms
- this shows even a slight concealment can provide survivial advantage for preys
36
Q
what is disruptive coloration
A
- a type of crypsis where the coloration of the body is broken up by bold contrasting patterns on periphery
- this would break up the body outline
- in moths: this was shown to be very effective in increased survivals rates and more effective than just using crypsis
37
Q
what is countershading?
A
- a type of crypsis
- because under sunlight, a shadow of the prey will appear obvious to predators
- some preys evolved countershadowing where the dorsal-sun facing side is dark and hence merges and combines with the shadow of the prey, making it not obvious under sunlight
- experiment showed higher survivals rate in preys which used countershadowing than ones which did not
38
Q
what is masquerade?
A
- resemblance of inedible objects suck as twigs, bird droppings, leaves or stones
- IT IS NOT CRYPSIS: as it is identified but just as a different object
39
Q
what is the difference between masquerade and crypsis?
A
- masquerade + crypsis both are types of camouflage
- crypsis is when the prey is not at all identifies
- byt masquerade is when the prey is identified, just as a different object
40
Q
what is an example where cryptic and aposematism is used?
A
- desert locust
- during juvenile solitary phase: it uses crypsis: it is small and green to avoid detection
- however under high population density these juveniles develop into large and brightly colored red, yellow, black and have a more active foraging style
- experiments show that predators learn to not attack brightly colored conspicuous preys faster than avoiding cryptic green. Hence a shift to aposematism in high density areas sreduced predation
41
Q
what are the 2 theories for the evolution of warning colors?
A
- aposematism includes distastefulness and conspicuousness. It is thought that conspicuousness evolved first as a strategy used for mate attraction, but as this colouration also made predators aware of their existence, it then evolved distastefulness to avoid prefation
- the second idea is fisher’s hypothesis where the evolution of warning colors evolved through their effect on survival of relative in the same group, to ensure that even though one is killed its relatives containing the same gene for warning colors can reproduce, and that this warning gene doesn’t go extinct
42
Q
what was fisher’s solution to the evolution of aposematism?
A
- fisher suggested that brightly colored insects usually clumped in family groups so that if a rare mutation or phenotype occured for aposematism, even tho a naive predator would eat that rare individual
- its family which potentially has similar genes can repeat this in the next generation
- challenges:
- phylogenetics analysis showed that actually aposematism occured before gregarious families, and hence it was more likely that aposematism was more advantage to family instead of the other way around
43
Q
what is the tradeoff between aposematism and predation
A
- cost os conspicuousness in increasing the probability of attack by naive predators
- vs benefits of increased protection by experiences predators through more memorable and detectable signalling
44
Q
what are the 2 types of mimicry
A
- mullerian mimicry: replleant species look aline
- batesian mimicry: palatable species mimic distasteful species (a type of dishonest signallingO
45
Q
what is mullerian mimicry, and how did it evolve?
A
- it is when color patterns of different repellent and distasteful species look similar
- evolution: Species B has a pattern which decreases predator attack than Species A. And species B has a larger population
- given that a predator need to attack a certain amount of species to learn distastefulness associated w a pattern, species A would extinct before this occurs due to small population
- however, if species A resembles species B is will be under the greater umbrella of protection, giving them a big advantage, as the predator doesnt have to attack and learn again
- rarer morphs evolve to mimic commoner morphs
46
Q
what is batesian mimicry and how did it evolve?
A
- cheating and dishonest signal.
- palatable species mimic distasteful species
- example: hoverflies mimic wasps; harmless snakes mimic venomous snakes
47
Q
what are the trade off in prey defences
A
- cost of aposematism:
* costly to wear: cost of thermoregulation. wood tiger moth which has black and orange colors. black parts have effected their ability for thermoregulation
* costly to produce: requires mor eenergy allocated to producing these colors - trade-off in crypsis vs conspicuousness?
* cost of being crypsis is that it wont be able to guard territory, and cant get male attantion
* benefit of being crypsis: escape predators
48
Q
what are the fundamental differences between the sexes
A
- their gamete sizes
- females produce large, immobile, food rich gametes - eggs
- male gamese are small, mobile - sperm
49
Q
what is an example of isogamous sexual reproduction?
A
- where 2 gametes fuse during sex are of similar or equal size
- i.e in sexual reproduction of paramecium
50
Q
what is sexual reproduction anisogamou sex
A
- when the larger egg fuses with a smaller sperm
- occurs in most multicellular plants and animals
51
Q
how did anisogamy evolve?
A
- anisogamy evolved from isogamy
- assume survival of zygote depends on its size
- larger zygote - more food to sustain its development and so the better chance at surviving
- larger gametes will be favored bys election if this increase in survival compensated the fact that larger gametes are produced in smaller quantities
- once larger gametes evolve, there will hence be immediate selection on smaller gametes to seek out larger gametes to fuse with, in order to parasitize their food reserve
- over time larger gametes evolve to resist smaller ones fusion, but this ultimately fails as small gametes are produced in such numbers
- moreover, the cost of a large gamete not resisting a small gamete’s attack is much less than the cost of a small gamete not finding a large gamete to fuse with
- this shows the ancient evlutionary arms race, of producing few large gametes and a lot of small gametes. Medium sized gametes lost during this race as they have neither the advantage of both sides
- this is shown w the comparative study of volvocales. in this family, unicellular algae where food reserves in zygote are unimportant show isogamy, whereas in multicellular algae where food reserve is important are anisogamy
52
Q
what is sexual reproduction?
A
- biparental mating - meiosis, recombination, segregation syngamy
1. 2 genomes fuse (syngamy) then separate (meiosis) giving rise to different combinations of genes becaus eof recombination and segregation
2. recombinayion changes how alleles at different loci on the same chromosome are organized
3. segregation changes how alleles on homologous chromosomes are packaged into individuals
4. sexual eproduction alters association and linkages among alleles
53
Q
the evolution of sexual reproduction in eukaryotes
A
- sexual reproduction is common and evolutionarily successful in eukaryotes -> giving them rise to different genetic combinations
- asexuality in eukaryotes is rare and evolutionarily recent, as they evolved again from sexual lineages
- recomination is not necessarily couple with sex as it evolved before sexual reproduction did
- biparental symmetrical sexual reproduction is unique to eukaryotes
54
Q
what is an example demonstrating sexual reproduction is common adn evolutionarily successful?
A
- cellular processes involved in sexual reproduction (such as syngamy, meiosis, and gametogenesis) are very complex and rely on a large number of genes.
- The example given is the nematode Caenorhabditis elegans, which has 1,416 nuclear genes identified in relation to these processes - which is a lot given that c elegans only have 20,000 protein coding genes
- suggests that sex is not something that just happened suddenly (or sporadically) in evolutionary history; rather, it has been a consistent part of eukaryotic life for a very long time.
55
Q
problems of sexual reproduction, male are useless
A
- Males are seemingly useless in population growth in both sexual and asexual scenarios
- In sexual scenarios: Females contribute more to population growth
- Females which bear offspring are more critical for population growth because they make babies
- At carry capacity sexual females can replace herself by producing one more offspring and maintaining the carrying capacity
- In Asexual females will produce multiple offsprings, and not just simple replacement, hence problem arises that if asexuality can directly contribute to population growth, and females can reproduce themselves to contribute to population growth, whatis the point of men??
- Male are very beneficial because of their ability to produce diversity giving efficacy of selection and red queen hypothesis
56
Q
what is the benefits of sex?
A
- spatial heterogeneity
- diversity
- efficacy of selection
- red queen hypothesis
57
Q
what is the 2 fold cost of sexual reproduction
A
- sexual reproduction is less efficient than asexual reproduction because it requires two individuals to create offspring, and typically only half of those offspring will be capable of further reproducing (in species where males do not give birth).
- while a sexual female will just replace herself in terms of population, an asexual female can more than replace herself, leading to a potentially faster population growth in asexual populations
- an asexual mutant theoretically should spread and outcompete sexual individuals because of the twofold cost of sex.
- however although the costs, the benefits of sex such as genetic diversity to allow populations to adapt in changing environments and against disease more effectively
58
Q
what are other costs of sexual reproduction
A
- apart from the obvious two fold cost of sex
- the cost of meiosis: recobination can bring beneficial new genetic combinations, but can also break apart combinations of genes which are well adapted to their environment
- The costs of mating: Costs of searching for mates and the costs of engaging in mating (intrasexual competition, intersexual conflict), including increased risk of predation or infection by a sexually transmitted disease
59
Q
what is the paradox of sex
A
- the fact that despite the costs associated with sexual reproduction
- it remains a prevalent form of reproduction
- when consideringa bout the potential adaptive benefits such as linkage disequillibrium…etc this benefit can offset the costs associated with it
60
Q
what are some of the considerations of adaptive benefits of sex?
A
- Linkage disequillibrium: if D>0 it the combination of 2 alleles occur more than expected in HW equillibrium
- Epistasis: positive epistasis: combine effect of mutations is mor ebeneficial than the sum of the effects of each individual mutation, negative epistasis: combined effect more detrimental
- the origin of sex evolved from asymmetric DNA transfer of DNA in bacteria. However the mechanism that maintains sex in eukaryotes is due to its benefits
- short term vs Long term: increasing variance may not seem too beneficial in the short term (given that it will only b beneficial in short term if it provides a very extreme benefit in fitness) however, it the long term, it is beneficial to allow more rapid adaptations
- linkage disequillibrium may break up advantageous combinations. However, it can also break up any current disadvantage associations and provide immediate benefits by creating more advantageous allele combinations
61
Q
what are some benefits of evolution of sex accoridng tor ed queen hypothesis
A
- antagonistic coevolution: parasites selected to infect the most common host genotype
- co-evolving parasites adapt to infect the locally common clonal genotypes, hence producting a negative frequency selections (common phenotypes are selected against)
- this causes the genetic combinations to change more rapidly depending on environment and responding to parasite infection
62
Q
what is an example of benefit of sexual reproduction according to red queen hypothesis
A
- P.antipodarum has both asexual reproduction and sexual reproduction
- when they are in shallow waters where co-evolving parasites are common, sexual reproduction is also common, as it provides diversity
- when in depper waters w fewer parasites, asexual reproduction is more common
- Moreover in anothe rresearch: showed that female flies infected by bacteria or parasitized by wasps produce mor recombinant offsprings compared to uninfected controls
- these show in parasitic threats, there is a selective advantage for organisms to sexually reproduce for more genetic diversity
63
Q
what is spatial heterogeneity
A
- the variation in environmental conditions and selective pressures across different geographic areas
64
Q
what is negative and positive epistasis and why does it matter
A
- negative epistasis means the current combination of genes is more negative to fitness compared to its additive effect (essentially 1+1>2)
- in this case, it would be better to break up these combination, as although it would lead to an extreme benefit, it does relieve the negative
65
Q
how is postive diequillibrium generated and what are its effects?
A
- positive disequillibrium is generated when some sites experience strong selection than other sites,
- OR when alleles are favorable in some locations and not favorable in others
- it is caused by migration mostly or sudden change in selective pressure
- when new alleles from a migrant come into populatuon, they create a disequillibrium which doesnt align with the genetic combination predicted and favored by local selection pressures
- when positive disequillibrium occurs which disrupts the local genetic associations, it is a short term advantage for sexual reproduction, to break down mis matches and create new combinations more favourable in local environment
66
Q
what is an experimental ecidence for spatial effects and spacial heterogeneity?
A
- species of rotifers can both reproduce sexually and asexually (facultative sexual species)
- in spatially heterogenous (different conditions in different spaces) the tendancy of sexual reproduction is higher
- whereas in homogeneous environments, rate of sexual reproduction evolves towards 0
- hence concludes spatial heterogeneity promotes and maintains evolution of sexual reproduction
67
Q
what is the william’s lottery model?
A
- an evolutionary theory describing advantage of sexu over asexual
- bet hedging strategy: by producing genetically diverse offsprings is ‘betting’ on some of their offsprings survive unpredictable environments
- sexual reproduction would be more common in temporally variable environments and asexual reproduction would be more common in stable environments
- also arguments from Bell 1982 against the model statingL asexual reproduction is found in unpredictable and temporary habitats
68
Q
what is the tangled bank hypothesis?
A
- another theory which tries to explain the maintenance of sexual reproduction
- in spatial heterogeneity locations: genetic polymorphism could be beneficial
- this theory refers to sexual reproduction is beneficial by reducing intraspecific competition in a constant environment. This is because, by producing genetically diverse offsprings in a contsant environment, it will allow them to sought out different niches and food sources and avoiding direct intraspecific competition, hence being advantageous even in constant environments
69
Q
what is the ruby in the rubbish hypothesis?
A
- a hypothesis which suggests that sexual reproduction is favored because it is easy to allow beneficial alleles to be separated from deleterious alleles due to recombination
- in asexual populations: beneficial mutations can be lost if it is surrounded by deleterious mutations, as it would be difficult to remove the deleterious mutatiosn without also removing the beneficial one
- whereas in sexual populations, this can be done faster by recombinations
70
Q
what is the pluralist approach of sexual reproduction?
A
- each hypothesis which tries to explain why sexual reproduction is maintained focus on certain conditions hence is not an overall approach
- these hypthesis are not mutually exclusive
- by using pluralist approahc which is combining and integrating multiple mechanisms better explain certain observations as sexual reproduction is not a single factor contributing to it
71
Q
what is the hill robertson interference, how is it solved by sexual reproduction
A
- hill robertson interference suggests that due to linkage disequillibrium, multiple loci are inherited together
- when multiple natural selection pressures act of linked loci genes, it decreases the efficiency of selection, and harder for beneficial alleles to be selected for if it is linked with a deleterious mutationbs
- sexual reproduction solves this as recombination reduces these interferences
72
Q
what is the fisher muller hypothesis?
A
- it is a hypothesis that suggests sexual reproduction allows beneficial alleles from different individuals to come together. This increases the chances that offspring will have combination of alleles that rae more advantagoues than those of either parent
- separates beneficial alleles from different background and uniting them into same genome
- when environmental changes are rapid and severe, the fitness benefits of being able to rapidly adapt may overcome the costs of sex
73
Q
what are some experimental evidence for fisher muller hypothesis?
A
- suggests that outcrossing using a facultative sexual algae
- alllowed faster adaptation to new medium than compared to asexual population
- and this is much more efficicent oin larger populations which have more chances to produce genetically variable offsprings
74
Q
what are some caveats about evolution of sex?
A
- Most hypotheses for sex are based on the notions that sex promotes genetic variation because segregation and recombination break down genetic associations, and that genetic variation is beneficial
- However…
- Sex doesn’t necessarily increase genetic variation
- Genetic variation isn’t necessarily beneficial
- Evolution doesn’t necessarily promote genetic exchange, even when genetic exchange does increase genetic variability and variability is favourable
- recombination evolved before sex, so why did sex need to evolve if recombination can solve these problems altogether?
75
Q
parental investment and parental care across animals
A
- in anisogamous sexual reproduction, females produce larger and fewer gametes, and hence once an offspring forms, the egg contributes more to offspring development
- in mammals females take up majority of offspring care from pregnancy to lactation
- in birds biparental care is norm, but females invest more into the care
- in other taxa normally female care is more than male care such as in invertebrates and reptiles
- and only in fish is male care more common: this is only because males can attract mates whilst guarding egg, and hence doesnt have to suffer cost of losing mating opportunities compared to other animals
76
Q
what is the link between parental investment and sexual competition?
A
- the parent which puts less care into the offspring will compete amongst themselves to mate with a member which invests more into offsprings
- hence sex which puts least parental investment has a greater rate of reproduction: males can fertilize eggs at a much faster rate than a female can to produce an offspring
77
Q
what is the sexual conflict between males and females in reproduction?
A
- females increase her reproductive success by rate of converting resources into eggs and offspring supply
- males increase reproductive success by increasing number of females it fertilizes, the more number the better
- hence male repro is limited by access to females
- and females repo is limited by resources
- therefore a conflict of interest occurs: as females want to choose a male who offers best resources or genes, whereas males simply want to exploit female investment and mate with as many females as possible even though they may not have the best resources
- this is an asymmetry in parental investment giving rise to sexual conflict, and hence sexual selection in behaviour and physiology
97
Q
what are the types of conflict which exist in a family?
A
- 3 types of conflict
1. parent offspring conflict: between generations: parents future vs current fitness
2. sibling conflict: within and across generations (resource allocation, selfishness)
3. sexual conflict: male and females
99
Q
what and how to determine optimal parental investment?
A
- how much should an individual parent care for an individual offspring
- depends on 2 factors
1. the trade off between size-number trade off. This can be modelled using optimality model. And this can vary depending on environment and type of organism. whether viviparous?
2. future vs current reproduction trade off. Again, this is highly variable depending on whether the organism is semelparous or iteroparous? and depending on how challenging or variable the environment is
102
Q
what is intra-brood conflict and inter brood conflict
A
- between generations of siblings and within the same brood generation of siblings
- now vs future and within current brood
114
Q
what is the hawks and dove game, how is it used in aggression
A
- it is a game theory
- The population can maintain both hawks and doves as long as the costs of fighting (for hawks) exceed the value of the resource. If the cost of fighting is low, or the value of the resource is very high, it always pays to be aggressive (a hawk).
- Frequency-Dependent Selection: Hawks and doves are maintained at equilibrium frequencies by frequency-dependent selection. This means the fitness of a strategy depends on how common it is. If there are too many hawks, they are more likely to fight each other, which is costly and reduces their fitness compared to doves. If there are many doves, hawks can exploit this and win resources without the cost of fighting.
- Equilibrium Frequencies: There’s an equilibrium point where the fitness of hawks equals the fitness of doves. If the proportion of hawks goes above this equilibrium, they are likely to fight other hawks, and the cost reduces their fitness below that of doves. If the proportion of doves is too high, hawks can always win resources without fighting, making their fitness higher than that of doves.
138
Q
graph of semelparity and iteriparity
A
- when reproductive costs/effort is high, should prioritise semelparous
139
Q
the iteroparous strategy
A
140
Q
semelparous strategy
A
155
Q
what is GSI and SSI
A
- GSI: gametophytic: it is when S-haplotypes are co-dominant in pistil, as long as one allele of the diploid on pistil, matches the haploid allele on pollen, then incompatible
- SSI: dominance exists: in pollen the parent’s genotype will determine which allele it has, and the pistil will also presen the dominant type
