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(^11) Today’s Outline Ecology (BIOL 250 ) Lecture 11 : Social Relations Announcements Mate Choice Radish^ Nonrandom Mating Among Wild Sociality Cooperative Breeders Green Woodhoopoes African Lions Eusociality (^22)
Introduction
!Behavioral Ecology: Study of social relations. "Interactions between organisms and the environment mediated by behavior. !Sociobiology: Branch of biology concerned with study of social relations. !Fitness: Number of offspring (genes) contributed by an individual to future generations. (^33) !Fundamental Question: "What is male and female? !Females produce larger, more energetically costly gametes. (e.g., eggs) !Males produce smaller, less energetically costly gametes. (e.g., sperm) "Female reproduction thought to be limited by resource access. "Male reproduction limited by mate access.
Introduction
(^44) !Hermaphrodites "Exhibit both male and female function. "Most familiar example is plants.
Introduction
(^55)
Mate Choice
!Sexual Selection "Differences in reproductive rates among individuals as a result of differences in mating success. !Intrasexual Selection: Individuals of one sex compete among themselves for mates. !Intersexual Selection: Individuals of one sex consistently choose mates among members of opposite sex based on a particular trait. (^66) Mate Choice and Sexual Selection
- in Guppies !Given a choice, female guppies will mate with brightly colored males. "Brightly colored males attract predators. "Color characteristics that have been shown to confer mating advantage: !Brightness !Number of spots !Total pigmented area
(^77) ! Endler performed natural selection study to test color pattern in guppies. "When freed from predation, average number of spots of male guppies increased. ! Kodric-Brown reported reproductive success was determined by a combination of male attractiveness and dominance status. "Observed attractive males tend to be dominant, court more, and have brighter colors. Mate Choice and Sexual Selection
Mate Choice
- Scorpionflies !Adult scorpionflies (genus Panorpa ) feed on dead arthropods in the forest understory. "Dead arthropod supplies are often limited. ! Thornhill found that male Panorpa will take possession of, and guard, dead arthropods. - Larger males are more successful. (^99)
Nonrandom Mating Among Wild Radish
!Wild radish flowers have both male (stamens) and female (pistils) parts, but cannot self-pollinate. ! Marshall found non-random mating in wild radish populations. (^1010)
Sociality
!Evolution of sociality is generally accompanied by: "Cooperative feeding "Defense of the social group. "Restricted reproductive opportunities. !Cooperation generally involves exchanges of resources or other forms of assistance. (^1111) !Eusociality "More complex level of sociality. !Three major characteristics:
- Individuals of more than one generation living together.
- Cooperative care of young.
- Division of individuals into non-reproductive and reproductive castes.
Sociality
(^1212)
Cooperative Breeders
!Species living in groups often cooperate in rearing offspring. "What benefit do helpers gain? !Inclusive fitness: Improve survival and reproductive rates of family members.
- Inherited territory: May increase helper’s probability of future reproduction and recruiting helpers. # Kin Selection
