Special reading- post copulation sexual selection 2 - cryptic female choice for nuptial gifts Flashcards
1
Q
Background info
A
In species which nuptial gifts facilitate meeting , females may gain indirect benefits through preferential storage of sperm from gift-giving males (if the gift signals male quality). This hypothesis was tested in the spider (pisaura mirabilis) by counting the number of sperm stored in response to copulation with male with/without a nuptial gift
2
Q
what is the hypothesis?
A
nuptial gift is a male signal under positive selection from females through cryptic sperm storage
3
Q
what is the methods?
A
- 3 groups - NG males - no gift and allowed to copulate with no interruption, GT males - offered a gift but had copulation times that matched NG males, G males - gifts and allowed to perform uninterrupted copulations
- also analysed number of sperm transferred, fecundity and egg hatching success
- froze half of the females to check sperm and let other half live to measure fecundity and hatching success
4
Q
what are the results for sperm count?
A
- Number of sperm in females spermatheca differed significantly among the 3 groups
- sperm count significantly lower in NG group compared with GT group - females in uninterrupted matings in G group stored significantly higher amounts of sperm compared to NG and GT
5
Q
results for hatching success?
A
- success differed significantly among groups
- lower in NG compared with GT group
- females in G group experienced higher hatching success than NG and GT
- positive correlation between copulation duration and hatching success
6
Q
meaning of results
A
- copulation duration is the biggest indicator of sperm storage and fertilisation success
i. e nuptial gift behaviour is very helpful - nuptial gifts in spiders is the males way of combating sperm competition
