L3 - Sexual Selection Flashcards
Define intrasexual selection
Intrasexual selection is where members of the same sex within a species compete with each other in order to gain opportunities to mate with others
Define intersexual selection
Often known as female choice, it is the process where the female choses the male based on certain ornaments
Describe the natural costs between sperm and eggs
Eggs are costly, scarces and immobile - females generally produce 1 a month
Sperm are produced all the time - millions a month
Give 2 ways in which selection could act against medium sized gametes?
1) They aren’t mobile enough compared to small ones
2) They don’t provide enough resources for the developing zygote compared to a large one
Describe the direct benefits of female choice
genetic predisposition to choose mates that provide resources beyond good genes - such as food or a nuptial gift
Bringing large nuptial gifts is time consuming and dangerous - shows a good male
Describe the influence of finding a male with good genetics for a females choice in sexual partner
Females receive an indirect benefit of passing good genes onto their offspring
the larger the harem of the father
What is the handicap principle in terms of female selection of males?
Handicap principle - as cost increases, fake-ability should decrease
What is Runaway selection?
The loci for 2 traits is found in males and females but only expressed in the appropriate sex
an sensory or a pre-existing bias affect a females choice in males?
Preference emerges for a trait as a consequence of the neurological response
E.g.: females prefer red berries –> red feathered males preferred (colour vision pre-ceded colourful plumage/skin)
How do male birds learn their songs?
Males: learn their songs from their parents/foster parents
Females pick males that sing songs like their parents
What is interference competition?
Bigger males scare away smaller ones
Females protest if subordinate males try to mate
What does larger harem’s in a population indicate?
Dimorphism - indicates intense male competition and this impacts on male size
