mating systems and sexual selection

Question 1

46 years ago…

Answer 1

thought 93% of passerines where monogomous, with polyandry unknown
-today it has been prove different

Question 2

extra-pair copulations and extra-pair paternity common

Answer 2

-genetics has shown that extra-pair offspring are found in 90% of species

Question 3

why have extra-pair copulations?

Answer 3

-increased genetic quality of offspring
-increased genetic variation
-social benefits of having multiple males to protect and care for the nest
dominant males get more paternity, while subordinate males make the best of what they get

Question 4

social monogamy

Answer 4

• one female and one male at nest, though EPC are still common
• few examples of mate fidelity seen with albatross and penguins

Question 5

polygyny

Answer 5

one male, multiple females, sometimes based on resource control, as in red-winged blackbirds

• extreme polygyny expressed in lekking species, ie. grouse
• 2% species overall do polygyny

Question 6

polyandry

Answer 6

• one female, multiple males, males incubate eggs and raise young
• in these cases females are often brightly coloured and defend territory, and initiate courtship
• present in less than 1 % of species

Question 7

polygynangry

Answer 7

• promiscuous, anything goes and/or communal mating

- seen in woodpeckers, ostriches

Question 8

cooperative breeding

Answer 8

-groups, often extended fammilies work together to raise young
cause by kin selection, ecological factors that encourage group living, ie. scare resources
-helpers can gain experience, inherit territory, and may sire their own offspring

Question 9

sexual selection

Answer 9

-advantage some individuals have over others of the same sex and species solely with respect to reproduction

Question 10

extreme sexual selection of bower birds

Answer 10

-mating displays of collected coloured items. the nicer the display and better colours, the more they are selected by females

Question 11

theory of sexual selection

Answer 11

different selection pressures on males and females leads to sexual dimorphism

• femaleshave higher investment in eggs, and more certainty of maternity, so usually they maximize fitness by taking care of eggs
• males, with small investment and less certainty maximize fitness by attracting more females

Question 12

intra-sexual selection

Answer 12

-male-male competition leads to elaborate signals, large body size, as honest indicators of ability to fight competitors

Question 13

inter-sexual selection: why do females choose elaborate signals

Answer 13

• honest indicators of direct benefits, such as ability to provide food, ie. carotenoids or songs, healthier=better songs
• honest signal of good genes through signs of health and self-handicapping to show they can survive with a predator attacting signal/display

Question 14

not all signals may be honest

Answer 14

• sensory bias/explotation can occur
• novelty is sometimes preferred, as it draws attention regardless of indication of quality or not
• optimal signal depends on receiver preference, and those preferences depend on variation in signals, not necessarily gene quality