Transcript Slide 1
In conclusion, there are 3 scenarios that may lead to Polygyny: (1) Females have no other choice but to mate with a mated male (2) Females may be deceived (3) Males control access to resources, but also Females may actively assess the consequences of their decisions and make an adaptive choice ....let
’ s examine this relationship between resources and females more closely in mammals....
Understanding variation in Mammalian mating systems is best understood in terms of what leads to a high or low POLYGYNY potential E.g., Female reproductive success is limited by access to resources, thus the distribution of females depends on
resource dispersion
(1) If females are
clumped
in space or
predictable
in time there is a higher POLYGYNY potential than if not clumped or predictable (2) If males can
defend
a territory or access to females either directly or indirectly via competition for resource rich sites there is a higher POLYGYNY potential than if defense is not possible
A Comparative Survey of Mating Systems in Mammals
Even distribution of resources, little polygamy potential Patchy distribution of resources, high polygamy potential
Females solitary and range defensible by males : In 60% of mammalian species the female is solitary and the male defends a territory that overlaps one or more female ranges - If female ranges are small relative to the area a male can defend – polygyny - If female ................ large ............................................................ - monogamy In the latter, usually the male deserts after mating, but in ~3% they stay to give parental care.
Marmosets carry young African wild dogs – coop. hunting, feeding Klipspringer - defense
Females solitary and range
not
defensible by males: Temporary, and wandering, association during estrus - monogamous
Orangutan Moose
Females
social
and range defensible by males: Can lead to permanent harem attached to male ’ s territory Several males (often relatives) may defend larger groups more successfully and increase length of tenure of a harem Colobus monkeys Hanuman langurs
Females social, range
not
defensible, but Female movements are predictable: Males defend small ranges and
wait
for females to pass through on the way to predictable routes...
...on the way to the waterhole...
...or to rich feeding grounds
Females social, range
not
Female movements
not
defensible, predictable Males
follow
females Elephants – small female groups
Seasonal Harems Seasonal estrus (predictability in time) – allows males to build up energy reserves for mating season and aggressively defend harems for the one month females are fertile. Permanent Harems when females do not all come into estrus at the same time ( unpredictability ) –
Summary: in mammals, mating systems are determined from the complex relationships between female range size, movement, sociality, predictability in time and space, and the male ’ s ability to defend a range solitary defensible range small: Mono large: Polygyny social Polygyny (harems) non-defensible Monogamy Polygyny of various sorts (including harems) depending on predictability of female movement and estrus
♀
= 5.0
♂
= 5.0
♀ ♀
β
= 3.8
= 3.8
♂
= 7.6
Lastly, multiple mating systems can occur within a single species, sometimes driven by environmental circumstances ♀
= 6.7
♂
= 3.7
♂
β