Lecture 6 Flashcards
What is swarming used for?
bringing together the sexes, usually above a landmark
leks - substrate based
males aggregate and one female selects
What are pheromones used for in insects?
bringing together the sexes
How are pheromones sensed?
through the antennae females can sense from very far away
How many compounds are in pheromones?
3-7 compounds
What is the cost to releasing pheromones?
other bugs can release the same pheromones and attract the insects and then eat them, females can release the pheromones, and then parasitic wasps smell the pheromone and parasitize her eggs
What is a cost to sexual selection?
if females select males, some traits will be exaggerated if the female continues to choose the males with that trait until the trait becomes so exaggerated that it is unmanageable and then the process reverses
What are the steps to mating?
- mounts female
- arrest the female - once accepted by the female, stops moving
- Nod head, lick antennae, she bends open her abdomen and mate, after head nod to release pheromones so that she doesn’t mate with another male
- Some bugs can give toxins to the females, and they will be protected from predation and the female can put it on the eggs as well to protect them
- Mating plug – closes the genital opening so that other males cannot mate and is also protein rich for the female and egg development
What is a nuptial gift?
- Nuptial gift: Presenting a gift to the female, if she accepts the gift she will eat it and then he has a chance to mate with her
What are spermatophores?
Spermatophores: tiny stocks of sperm on a plant for females to find (must be quickly so that they don’t dry out)
What can males transfer during mating?
transfer a substance that makes female unreceptive, cost benefit ratio to the male, the more the male remates with other females, the less time the unreceptiveness of the females he mates to will last
What is mate guarding?
investment of time
ensuring fertilization
cost-benefit anaylsis for how long to guard
penis with bristles on the end: empty genital oviduct from the sperm of another male, therefore now the other males must guard the female
What are some characteristics of honeybee mating?
- during flight
- after mating the dying male is disconnected, penis has hooks so once he disconnects, leaves penis with seminal vesicles behind
- this hinders next mating
- females must remove penis to ovipost
- sperm storage can last for years
What is the summary of the war of the sexes?
Males produce:
- sperm
- anti-aphrodisiacs
- nutrients
- toxins
males compete in sperm competition
Females:
- select males
- restrict access to spermatheca
What is traumatic insemination?
in bed bugs, stab female in the abdomen with penis
What is mating like for parasitoids?
- males wait for females
- perception of pheromone
- immediate mating
What is oviposition?
the laying of eggs
What is a special feature of insect eggs?
have a glue that protects eggs from plants, however plant changes volatiles which attracts parasitic wasps to the eggs
How might some insects care for eggs?
carry them on their back
How do aphids give birth?
to live larvae
What is the difference between homomorphic sex chromosomes and hetermorphic sex chromosomes?
homomorphic - X and Y chromosomes exhibit few differences from each other in size and gene content, difficult to distinguish
hetermorphic - X and Y chromosomes are very different from one another
What are sex chromosomes like in insects?
Fruit flies have the same as humans, but some fruit fly species have X and nothing else for the males
Grasshoppers are the same, where the males have only X
What is special about sex chromosomes in insects?
Haplodiploidy - Haploid (n) male and diploid (2n) female, there are no heteromorphic chromosomes
What is complementary sex determination?
HETEROZYGOUS: The only way for a female to be born is if the haploid allele from the male and one (heterozygous) allele from female come together
If one allele from male and female come together but they are the same allele (homozygous), it will be an non viable male gamete
HOMOZYGOUS: Viable male gametes can be produced when either allele from the female is used for a haploid gamete thus resulting in a male (n)
What is the cost for diploid males?
low survivorship (less fit)
sterile
