Chapter 10: Life history and reproductive strategies

Question 1

Name some general life history traits

Answer 1

• forage at sea
• aqatic m. mamms reproduce and spend life at sea
• amph m. mamms reproduce, rest & molt on land/ice
• large variation in body size
• large animals: long lived, grow slow, delay sex,
• large animals: few offspring, invest heavily
• usually one offspring
• gestation 7-17 months
• embryonic diapause in pinnipeds and otters

Question 2

sexual maturity traits

Answer 2

• delayed, trade off investing energy in Growth vs. reproductoin
• pinniped are 3-7yrs
• mysticetes are >7yrs
• odontocetes are 2-20 years
• sexual bimaturation
• density dependent changes ( low sex mat after Heavy whaling)
• birth intervals 1-7yrs

Question 3

Parental care

Answer 3

males contribute little or nothing

Question 4

male competitions

Answer 4

• contest
• endurance
• scramble
• mate Choice
• sperm comp

Question 5

basic male mating strategies

Answer 5

• defend territories containing Resources used by females
• defend non-Resource based territories, behave to attract females ** double check this one in book*
• follow or defend one or more females directly
• search for receptive females, spendig little tie With them to mate (search for sluts)

Question 6

basic female mating strategies

Answer 6

• Accept males that attempt to mate With them
• investigate and choose males based on benefits
• mate promiscously, promotes sperm compititoin
• incite male-male aggressive encounters and mate With winner

Question 7

what are pinniped receptivity themes?

Answer 7

• synchronously receptive
• spatial separation
• suitable land/ice for breeding

Question 8

why are most marine mammal so large?

what is another reason?

Answer 8

• b/c of thermoregulation needs as well as the need of large lipid stores to enable the animal to survive a long time w/o food
• larger animals have greater capacity to spend longer time under water

Question 9

most marine mammals reproduce at sea. which are the exceptions?

Answer 9

• pinnipeds
• otters
• polar bears

Question 10

why is it important to store large amounts of blubber?

Answer 10

reproduction requires fasting.

Question 11

what is embryonic diapause? why does it exist?

Answer 11

• when there is a delay in development of the blastocyst after fertilization.
• the need to synchronize the timing of breeding, common with highly seasonal breeders when males and females are spatially separated outside the breeding season

Question 12

what species has the longest gestation period?

Answer 12

beaked whale

Question 13

how does density affect age of maturity?

Answer 13

low density pops have lower age of maturity

Question 14

when is the potential for males to fertilize multiple mates highest?

Answer 14

when females are moderately asynchronous and spatially clumped.

Question 15

of marine mammals, who are the most synchronous in timing of receptivity?

Answer 15

pinnipeds (harp and hooded seal, 10-15 days)

Question 16

what is the most important factor underlying high synchrony?

Answer 16

the spatial difference between aquatic food resources and limited suitable land or ice habitats for giving birth

Question 17

who are the most asynchronous for receptivity?

what makes this situation easier for the population?

Answer 17

sirenians. 6 months.

- there are a small group of females which are available year round.

Question 18

mysticetes’ synchronosity is linked to what? what is the outfall?

Answer 18

climatic season

impossible for males to monopolize several females.

Question 19

what are four reasons for female clustering?

CHECK OUT THIS IN BOOK: TABLE 10.2

Answer 19

• marginal male * LOOK UP THIS IN THE BOOK*
• selfish herd
• male harassment
• thermoregulation

Question 20

what is the spatial distribution theme of female odontocetes?

Answer 20

• groups vary in size between 1-2 river dolphins to 10 000 pelagic dolphins
• communal care for young
• hierarchal groups

Question 21

what is the female special distribution of sirenians?

Answer 21

dugongs and manatees are normally a mother with their calves, though aggregate at food patches.

Question 22

what is the female dispersion summary for terrestrial breeding pinnipeds?

Answer 22

• annual reproduction
• synchronous reception
• spatially aggregated
• males compete heavily to monopolize access to females

Question 23

what is the female dispersion summary for aquatic mating pinnipeds?

Answer 23

• synchronized, but mobile and more dispersed

- males less competition for females

Question 24

what is the female dispersion summary for sirenians and mysticetes?

Answer 24

• females solitary
• multiyear reproductive cycles
• least competition by males

Question 25

what is the female dispersion summary for odontocetes?

Answer 25

- females in social groups - males compete to monopolize females, but less effective due to large home ranges, multiyear cycles, and extended breeding periods.

Question 26

what are male mating strategies for terrestrial mating pinnipeds?

Answer 26

- Otariids: polygyny - male territorial resource based defense of birth places and thermoregulation places - males arrive first on breeding places - establish boundaries to other males - exclusive access to females in their territories

Question 27

how does it work when the reproductive strategy is that male pinnipeds do not reach the breeding grounds until females do?

Answer 27

they do not defend territorial resources, but defend the females directly, moving as the females do.

Question 28

what are male mating strategies for aquatically mating pinnipeds?

Answer 28

roving, defense of single females, clustered males advertising vocally to females

Question 29

what are the male mating strategies for cetaceans?

Answer 29

-humpys sing songs, compete directly and escort females

Question 30

why do we believe humpys sing songs?

Answer 30

- attract females - lek - space between males - establish dominance.

Question 31

define 'lek'

Answer 31

A lek is an aggregation of males that gather to engage in competitive displays that may entice visiting females who are surveying prospective partners

Question 32

what is the male mating strategy of right whales?

Answer 32

- sexually active all year - gestation 1 yr - huge testes - multiple males mate with one female, sperm comp.

Question 33

what is the male mating strategy of bottlenose dolphins?

Answer 33

- males form alliances with other males - capture females - aggressive herding - temporary courtship w/o aggression - females cycle multiply and associate with several males

Question 34

which species has the shortest lactation period? which has the longest?

Answer 34

- hooded, 4 days | - sperm, >7 years

Question 35

which group of animals continue to suckle after lactation ends for social reasons?

Answer 35

odontocetes

Question 36

do odontocetes fast while maternal?

Answer 36

no, they have no fast, no long migrations

Question 37

how is milk composition related to length of lactation?

Answer 37

shortest lactation equals fattest milk