Chapter 10: Life history and reproductive strategies Flashcards
Name some general life history traits
- 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
sexual maturity traits
- 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
Parental care
males contribute little or nothing
male competitions
- contest
- endurance
- scramble
- mate Choice
- sperm comp
basic male mating strategies
- 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)
basic female mating strategies
- 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
what are pinniped receptivity themes?
- synchronously receptive
- spatial separation
- suitable land/ice for breeding
why are most marine mammal so large?
what is another reason?
- 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
most marine mammals reproduce at sea. which are the exceptions?
- pinnipeds
- otters
- polar bears
why is it important to store large amounts of blubber?
reproduction requires fasting.
what is embryonic diapause? why does it exist?
- 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
what species has the longest gestation period?
beaked whale
how does density affect age of maturity?
low density pops have lower age of maturity
when is the potential for males to fertilize multiple mates highest?
when females are moderately asynchronous and spatially clumped.
of marine mammals, who are the most synchronous in timing of receptivity?
pinnipeds (harp and hooded seal, 10-15 days)
what is the most important factor underlying high synchrony?
the spatial difference between aquatic food resources and limited suitable land or ice habitats for giving birth
who are the most asynchronous for receptivity?
what makes this situation easier for the population?
sirenians. 6 months.
- there are a small group of females which are available year round.
mysticetes’ synchronosity is linked to what? what is the outfall?
climatic season
impossible for males to monopolize several females.
what are four reasons for female clustering?
CHECK OUT THIS IN BOOK: TABLE 10.2
- marginal male * LOOK UP THIS IN THE BOOK*
- selfish herd
- male harassment
- thermoregulation
what is the spatial distribution theme of female odontocetes?
- groups vary in size between 1-2 river dolphins to 10 000 pelagic dolphins
- communal care for young
- hierarchal groups
what is the female special distribution of sirenians?
dugongs and manatees are normally a mother with their calves, though aggregate at food patches.
what is the female dispersion summary for terrestrial breeding pinnipeds?
- annual reproduction
- synchronous reception
- spatially aggregated
- males compete heavily to monopolize access to females
what is the female dispersion summary for aquatic mating pinnipeds?
- synchronized, but mobile and more dispersed
- males less competition for females
what is the female dispersion summary for sirenians and mysticetes?
- females solitary
- multiyear reproductive cycles
- least competition by males
what is the female dispersion summary for odontocetes?
- females in social groups
- males compete to monopolize females, but less effective due to large home ranges, multiyear cycles, and extended breeding periods.
what are male mating strategies for terrestrial mating pinnipeds?
- 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
how does it work when the reproductive strategy is that male pinnipeds do not reach the breeding grounds until females do?
they do not defend territorial resources, but defend the females directly, moving as the females do.
what are male mating strategies for aquatically mating pinnipeds?
roving, defense of single females, clustered males advertising vocally to females
what are the male mating strategies for cetaceans?
-humpys sing songs, compete directly and escort females
why do we believe humpys sing songs?
- attract females
- lek
- space between males
- establish dominance.
define ‘lek’
A lek is an aggregation of males that gather to engage in competitive displays that may entice visiting females who are surveying prospective partners
what is the male mating strategy of right whales?
- sexually active all year
- gestation 1 yr
- huge testes
- multiple males mate with one female, sperm comp.
what is the male mating strategy of bottlenose dolphins?
- males form alliances with other males
- capture females
- aggressive herding
- temporary courtship w/o aggression
- females cycle multiply and associate with several males
which species has the shortest lactation period? which has the longest?
- hooded, 4 days
- sperm, >7 years
which group of animals continue to suckle after lactation ends for social reasons?
odontocetes
do odontocetes fast while maternal?
no, they have no fast, no long migrations
how is milk composition related to length of lactation?
shortest lactation equals fattest milk
