BIOC51H3 Lecture : Readings 14 notes
11 Aug 2010
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Readings 14
Pg. 401-425 (refer to Figures 11.5 and 11.6, pg425, and iguana example)
-sexual dimorphism is the difference between the males and females of a species
-ZZ}Ç}(À}oµ]}vÇvµoo]}vv[Æo]vÁZÇ(uovuodifferent
or why certain traits exist
-if there is heritable variation in a trait that affects the ability to obtain mates, then variants
conducive to success will become more common over time
-mothers typically make a larger parental investment in each offspring than fathers
-parental investment is referred to as the energy and time expanded both in constructing an
offspring and in caring for it
-parental investment increases the reproductive success of the offspring receiving it but
decreases the remaining reproductive success in future additional offspring
-(uo[}v]o}µ]ÀµÁ]ooo]ÀoÇuoovZo]Ì
reproductive success is limited more by the number of eggs she can make than by the number
of mates
-uo[}v]al reproductive success will be relatively large and his realized reproductive
success is likely to be limited more by the number of females he can convince to mate with
him than the number of ejaculates made
-sexual selection is a more potent force in the evolution of males than in females
-heritable traits associated, in males, with failure to mate will tend to disappear, while heritable
traits associated with mating success will become more common
-when sexual selection is strong for one sex and weak for the other:
x Members of the sex subject to strong sexual selection will be competitive
x Members of the sex subject to weak sexual selection will be choosy
-not all males try to mate with as many females as possible and not all females are choosy for
certain reasons
-members of the competitive sex fight amongst themselves for direct control of mates, control
of a resource vital to mates, or to just fight for the sake of it
-intrasexual selection is the form of sexual selection in which the key event that determines
the reproductive success involves interactions among the members of a single sex
-fighting between members of the single sex is a form of intrasexual selection
-intersexual selection is a form of sexual selection in which the key event that determines
reproductive success involves an interaction between members of the two sexes
-males displaying colours, dancing or singing to females is a form of intersexual selection
-outright combat is the most obvious form of male-male competition for mates
-large body size, weaponry, and armor are morphological traits that are favoured as well as
tactical cleverness
-male-male combat can also lead to the evolution of alternative male mating strategies
-Zou]vv}(uo[u]vPµ]vdent on whether his sperm fertilizes
eggs
-sperm from different males will be in competition to fertilize the egg
www.notesolution.com
