Week 7 Flashcards
What is cryptic female choice?
Female mediated morphological, behavioural or physiological mechanisms that bias fertilisation toward sperm of specifc males
What was a study that had thought to have proven cryptic female choice?
H.nigriceps (Highland streaked tenrec) males offered prey of blow fly (Lucilla cuprina)
Larger fly meant long mating duration = higher fecundity
What was an issue with the idea that H.nigriceps females undergoing cryptic female choice?
Not confirmed to be female choice
Males influencing sucess by catching bigger prey, so male prey can influence sperm
When does cryptic female choice occur?
Opportunities for cryptic female choice occur when females mate polyandrously
What was an experiment were they tested for the importance of cryptic female choice?
In atlantic cod (Gadus morhua)
9 males and 8 females
Performed every cross combination (monogamously) (n=72)
Calculated survival for each cross
What was the average survival of the female atlantic cod offspring when they mated monogomously?
The offspring had a 1/3 chance of survival
What was the average survival of the female atlantic cod offspring when there were two males to choose from?
Survival for female offpsring increased to 0.45
What was the average survival of the female atlantic cod offspring as the number of males to choose from increased?
There was an increase in the survival rate everytime an additional male was added
When 9 males were reached offspring surival rate was 0.55, almost doubeled surival rate of offspring
What are the benefits of cryptic female choice?
If females could encourage fertilisation by the best of all the males- there are big gains to be made
What are the problems with provinf cryptic female choice?
Difficult to dissect apart male effects from female choice because often females benefit form being fertilised by the best male
What is an example that question cryptic female choice?
Why might big antlers win more fertilisations?
Cryptic female choice for males with big antlers or males with big antlers have more competitive sperm/get more matings/ better times matings
How did they try to prove cryptid female choice in arctiid moth (Utetheisa ornatrix)?
Mated female with a larger and smaller moth and then tracked paternity
Bigger male moths had more offspring so was seen as female choice for bigger male to fertilise more eggs
What was wrong with the experiment trying to prove cryptif female choice in arctidd moth?
The bigger male was more competitive sperm meaning it isnt cryptid female choice
How did they prove that it wasnt cryptic female choice in arctidd moths?
Virgin male spermatophore was bigger than mated spermatophore
Small male was virgin and large male was mated
More small males had more offspring, male size is irrelevant, the spermatophore size is what counts
What is an example of cryptic female choice in guppies?
Females prefer brighter males
Male guppies stripped of gametes
Sperm numbers equalised
Sperm mixed from two males
Females inseminated
Paternity tracked in relation to male colour
What were the results of testing for cryptic female choice in guppies?
Both orange and blue males there was an increase in relative paternity the brighter the colour the guppy was
This is potentially CFC as no males were involved removing mating behaviour and they controlled movement was sperm
What is potentially a reason for why guppies do not undergo cryptic female choice?
Do brighter males have better sperm meaning it is male sexual selection not CFC
What are potential opportunities for cryptic female choice?
Disrupt/encourage sucessful copulation/ insemination
Differential sperm transport
Differential sperm storage
Differential sperm-egg compatibility
Selective ovulation/oocyte/embryo reabsorption
What are potential oppotunities for cryptic female choice?
Complex mating behaviour
Complex female tracts and sperm management
Sperm ejection
What are an example of complex mating behaviours for cryptic female choice?
Male fly stratch eyes of females potentially to influence CFC by suggesting high quality but could be sexual reproduction
What are an example of complex female tracts and sperm management influencing for cryptic female choice?
Chelmorpha alterans (tortoise beetle). Inserted in bursa then have to travel to the spermatheca which is a long distance away so favours higher quality sperm
What are an example of sperm ejection influencing cryptic female choice?
Wild fowl low ranking males had a higher probability of sperm rejected after mating compared to high ranking males which had less probability of sperm rejection
What is a benefit of CFC to increase diversity?
Females want enough genetic difference that offspring are diverse eg lots of heterozygosity so they are more likely to survive
Though not so genetically distant that they mate with another species which can led offspring to not survive to birth or be infertile
How did they show CFC preventing incest?
Pair female to two different males (crickets) in a sequence, one of which is more compatible but only to her then measure reproductive fitness
What mating pairs did they set up to show CFC on preventing incest in crickets?
Female x Brother 1 then Brother 2
Female x Unrelated 1 then unrelated 2
Female x Brother 1 then unrelated 2
Female x Unrelated 1 then brother 2
In crickets what was the difference between proportion of eggs hatching between sib + sib and non + non?
Sib + sib hatch proportion was 0.33
Non + non hatch proportion was 0.55
What was the expected proportion of eggs hatched with 1 related and 1 not related male if no CFC?
Around 0.45, half of eggs fertilised by each so it will come to be in between the two proportions
What were the results of related + non related breeding pairs with cricket females?
Sib then non had a hatch proportion of 0.58
Non then sib had a hatch proportion of 0.51
As both are higher than expected then it shows that there is some CFC
How can female crickets avoid inbreeding?
Can be done through sperm storage, promiscuous females avoid inbreeding by having a higher proportion of sperm in spermatheca of non related males
With sperm storage having a direct correlation on ferilisation sucess
What is a conspecific cross with salmon and trout?
Salmon sperm x salmon eggs or trout sperm x trout eggs
What is a hybrid heterospecific cross with salmon and trout?
Salmon sperm x trout eggs or trout sperm x salmon eggs
How did they show that salmon and trout can cross breed?
Both species are external ferilisers so they took eggs and sperm from both and mixed it up. This saw that both trout eggs and salmon eggs had a high chance of being fertilised by trout sperm or salmon sperm
What is the competitive nature of conspecfic and heterospecific cross with trout and salmon sperm and eggs
Conspecific sperm are always more competitive with eggs of the same species –> seen in both salmon and trout
Roughly 70% conspecific to 30% heterospecific
How did they test for what decides the preference for conspecific sperm in trout and salmon?
Tested whether it was the egg itself that was prefered or the environment eg ovarian fluid
How did they test for the importance of ovarian fluid?
Salmon sperm + trout sperm with salmon eggs and salmon ovarian fluid
Salmon sperm + trout sperm with trout eggs and salmon ovarian fluid
Salmon sperm + trout sperm with salmon eggs and trout ovarian fluid
Salmon sperm + trout sperm with trout eggs and salmon ovarian fluid
What was the results of changing the ovarian fluid with the species of egg?
Fertilisation was fully dependant of ovarian fluid identity
In salmon ovarian fluid salmon sperm had a higher reproductive success than trout sperm for both species eggs
This was seen but in the reverse with trout sperm doing better in trout ovarian fluid