Chapter 10 Part 3

Question 1

Inbreeding avoidance hypothesis

Answer 1

in the context of mating, females mate polyandrously to avoid inbreeding with their social partner

Question 2

Avian examples providing evidence for inbreeding avoidance hypothesis

Answer 2

red-backed fairy-wren: females paired with genetically similar males most likely to produce offspring with extra pair males that were more heterozygous than offspring produced with pair mate

purple-crowned fairy wren: highly incestuous species; limited dispersal opportunities forces pair-bonding with ones own offspring if pair-mate dies; these relationships lead the female to have extra-pair copulations and resulting extra pair offspring (43% of incestous pairs resulted in extra pair offspring vs. only 3% of nonincestous pairs)

Question 3

Direct benefits of polyandry can be explained by what three hypothesis?

Answer 3

additional resources hypothesis, additional care hypothesis, and infanticide reduction hypothesis

Question 4

Additional resources hypothesis

Answer 4

females mate polyandrously to gain access to additional resources from their partner

Question 5

Examples providing support for the additional resources hypothesis

Answer 5

female red-winged blackbirds - can forage for food on territories of male they’v have extra pair relations with

bees - can collect nectar and pollen if they’ve mated with extra pair males; also seminal fluid from males may combat dehydration in females

insect species - nutritious spermatophores - more mates, more of these

polyandrous butterfly species - more protein in spermatophores, may be up to 15% of males body weight (good gift!); the more males they mate with the greater output of eggs

Question 6

Additional care hypothesis

Answer 6

females mate polyandrously to gain more caregivers to help rear young

Question 7

Examples providing support for the additional care hypothesis

Answer 7

Dunnock (european songbird) - encourage subordinate males to stick around by copulating with them when their pair-mate dominate males are away; can mate 12x/hour and may mate hundreds of times before laying a clutch of eggs; then utilizes parental care from both alpha and beta males

superb starling - unpaired males that mate with a paired female will help raise brood

Question 8

infanticide reduction hypothesis

Answer 8

females mate polyandrously to create greater uncertainty about the paternity of offspring in order to reduce the risk of infanticide

Question 9

Examples providing support for the infanticide reduction hypothesis

Answer 9

hanuman langur - males ignore the baby if they’ve previously mated with the mother

Question 10

Polygyny = multiple mating by ______

Answer 10

males

Question 11

What four hypotheses help explain polygyny in males?

Answer 11

female defense polygyny hypothesis, resource defense polygyny hypothesis, lek polygyny hypothesis, and scramble competition polygyny hypothesis

Question 12

What is the most common mating system in nature?

Answer 12

polygyny

Question 13

Female defense hypothesis

Answer 13

hypothesis explaining polygyny; when resources are evenly distributed in space but females form groups to better access those resources or to help dilute the risk of predation, males will follow and guard a group of females

Question 14

Resource defense hypothesis

Answer 14

hypothesis explaining polygyny; when resources are clumped, attract multiple females, and are easily defensible, males will guard the resources - and by extension the females - by setting up a territory

Question 15

lek hypothesis

Answer 15

hypothesis explaining polygyny; when resources are distributed heterogeneously and females are widespread and do not form groups, males will wait for females to come to them

Question 16

scramble competition hypothesis

Answer 16

hypothesis explaining polygyny; when resources are distributed heterogeneously and females are widespread and do not form groups, males will seek out females

Question 17

Evidence for female defense polygyny

Answer 17

siphonoecetine amphipods - females with elaborate cases may be glued to male (up to 3)

male lions - pride of females that have gathered together to defend permanent hunting territories and protection against infanticidal males

Montezuma oropendola (tropical blackbird) - nesting females group nests; dominant male can secure up to 80% of matings if he drives other potential mates away

plains zebra - females practice harem defense polygyny; females form groups to defend against risk of predation and advances of bachelor males; makes it easy for males to monopolize the entire group; females associated with dominate males are able to feed 10% longer/day

Question 18

social monogamy (frequently, always, never) occurs in mammal species in which females form groups

Answer 18

never

Question 19

in most polygynous species, the behavior of the ________ dictates the behavior of the _______ and ultimately the type of mating system

Answer 19

1) female

2) male

Question 20

Grevy’s zebra and resource defense polygyny

Answer 20

females do not group together nor are overseen by males; females tend to be found in locations where food resources are scarce and unevenly spread; males dominate the resource rich areas (water) where receptive females tend to be

Question 21

African cichlid fish and resource defense polygyny

Answer 21

males acquire a midden (batch) of empty snail shells that females use to lay their eggs in: the more shells he has the more females he will have

Question 22

black-winged damselflies and resource defense polygyny

Answer 22

defend floating vegetation that serves as safe location for eggs (and a defensible resource)

Question 23

antlered flies and resource defense polygyny

Answer 23

fight for rot spots on fallen trees that serve as nesting locations for females

Question 24

neotropical harvestman spider and resource defense polygyny

Answer 24

males parental care, shown if he already has eggs in his burrow, and the resource of the burrow itself leads to additional female

Question 25

When resources were experimentally redistributed among a dunnock songbird populations territory..

Answer 25

females given extra resources began to have reduced ranges and fewer social mates and female polyandry was replaced by female monogamy (males were also better able to monitor females kept in smaller territories)

Question 26

Lek polygyny

Answer 26

lek = display area used to attract females; not necessarily full of any useful resources

Ex. white-bearded manakin; preferred males occupy central locations within the lek and engage in more aggressive displays

high reproductive skew is standard among lekking species (high inequalities in male mating success)

Ex. Topi lek; older males are preferred mates centered in the middle of the lek

Ex. west African hammer-headed bat; 6% of the males accounted for 80% of matings

Question 27

Lekking evolves when..

Answer 27

other mating tactics do not pay off for males, typically due to a wide and even distribution of females

Question 28

Hypothesis explaining lekking behaviors

Answer 28

hotspot hypothesis, hotshot hypothesis, and female preference hypothesis

Question 29

hotspot hypothesis

Answer 29

males cluster in places (called “hotspots”) where the routes frequently traveled by receptive females intersect

Question 30

hotshot hypothesis

Answer 30

subordinate males cluster around highly attractive males to have a chance to interact with females drawn to these “hotshots”

Question 31

female preference hypothesis

Answer 31

males cluster because females prefer sites with large groups of males, where they can more quickly, or more safely, compare the quality of many potential mates

Question 32

Evidence in support of the hotshot hypothesis

Answer 32

removal of a preferred male in the great snipe sandpiper led to dispersion of subordinate males away from that area

Question 33

evidence in support of the hotspot hypothesis

Answer 33

indian peacocks gather in locations where females would have increased presence; tropical manakins are located in areas rich in resources that are attractive to females

Question 34

evidence in support of the female preference hypothesis

Answer 34

minimal support

Question 35

Scramble Competition Polygyny

Answer 35

when the costs of establishing territories exceed the benefits, males may simply seek scarce receptive females

Question 36

Examples of scramble competition polygyny

Answer 36

photinus firefly; thirteen-lined group squirrels

Question 37

explosive breeding assemblage

Answer 37

the temporary formation of a large group of mating individuals

Ex. horseshoe crab, wood frog

Question 38

Polygynandry

Answer 38

tends to occur in species that form social groups; driven by density of the species and of resources

Question 39

Examples of polygynandry

Answer 39

dunnocks (who display all types of mating systems) - most groups are made up of 2 males and 2 females

alpine accentor - typically made up of 1 dominant male, 1-3 subordinate males, and 2-4 females

Question 40

Promiscuity

Answer 40

most common in species lacking parental care

Question 41

examples of promiscuity

Answer 41

great tinamou - young are precocial requiring minimal parental care and enhanced parental freedom (females are the promiscuous sex)

marine snail - both sexes mate freely and frequently and only the females provide parental care only until eggs hatch

seaweed fly - no parental care is provided by either sex (convenience polyandry)

Question 42

convenience polyandry

Answer 42

a form of polyandry in which a female will struggle with a male but acquiesces t his mating attempts in order to save time and energy