sex allocation

Question 1

sex-determination is

Answer 1

genetic
environmental

Question 2

fishers theory

Answer 2

equal investment

Parents pass on genes to future generations via both sons and daughters, so parental fitness (proportional contribution) is W = f/F + m/M

Negative frequency dependence keeps populations at equilibrium

Only at equilibrium does every sex ratio offer equal fitness to parents

Question 3

sex ratios of danis

Answer 3

expected 0.96 males : 1 female
actual 1.07 males : 1 female

Question 4

Assumptions in Fisher’s model

Answer 4

Infinite population with random mating and equal dispersal of the sexes

Relax dispersal assumption

Question 5

Local Resource Competition

Answer 5

relatives of the same sex compete for the same local resource

Question 6

Local Resource Enhancement

Answer 6

non-dispersing offspring
cooperate rather than compete

seychelles warbles

Question 7

Local Mate Competition

Answer 7

Relax random mating assumption

When offspring mate on a local patch before dispersing, the equilibrium sex ratio becomes a function of number of egg- laying females

Question 8

Ovipositing females are very good in estimating…

Answer 8

… how many other females lay eggs

Question 9

what do seychelles warbles sex ratios suggest

Answer 9

pre-ovulation female control

(NB – females are the heterogametic sex (ZW) in birds)

Question 10

Alternative mating phenotypes

Answer 10

Males either eclose with sexual ornaments (ample resources as larvae and grew big)

or they eclose without to become satellite

Switch expected and observed when having horns starts to pay-off in fitness

Genetic threshold body siz

Question 11

Sex allocation in variable environments

Answer 11

Lifetime reproductive success of sons increases more steeply with condition than LRS of daughters
- depends on maternal condition during pregnancy

Females mated to males with brighter colors (UV) produced more son

Question 12

Environmental sex determination

Answer 12

environment that allows the best growth conditions will produce the sex that benefits most from growing up under optimal conditions

Same principles in species that change sex

Question 13

Sex ratio conflicts

Answer 13

When relatedness to offspring of different sexes is different

When transmission of other ”interested parties” is dependent on the sex of offspring

Question 14

Imprinted genes

Answer 14

”remember” the parent that contributed them
- under selection to bias parental investment when the maternal and paternal interests differ

Genes on sex chromosomes

Question 15

Other interested parties

Answer 15

Extrachromosomal genes, genes in organelles, or in endosymbionts

if uniparentally inherited (male killing, feminisation, loss of sex)