Behavioral Ecology

behavior

the correspondence of behavioral traits and the environmental circumstances (both ecological and social) in which they are expressed

2 types of behavioral studies

1. mechanisms of behavior — HOW behaviors occur

2. evolution of behavior — WHY behaviors occur

secondary sexual characters

genetic modifications of entire species manifest in ONE SEX ONLY — ex: sexual dimorphism in body size, fur/feather characteristics, color, canine development, and horns

sexual selection

produces traits of organisms that have interactions with social environments — special component of natural selection that depends on the SOCIAL environment (driving force is social competition for reproductive advantages)

limiting sex

the sex in short supply during the mating season (most often females, the opposite sex is the limited sex)

sex role reversal 

components of sexual selection are reversed such that males are the limiting sex (seahorses)

2 components of sexual selection

1. intrasexual competition

2. epigamic selection

intrasexual competition

competition among same-sex individuals for opposite sex individuals to mate with

epigamic selection

selection of mates by the limiting sex

mating system

general behavioral strategy employed in obtaining mates

6 characteristics of mating systems

1. number of mates

2. manner of mate acquisition

3. presence/characteristics of any pair bonds

4. patterns of parental care provided by each sex

5. patterns of parentage

6. sex ratio of receptive/active males and females

4 general types of mating systems

1. monogamy: 1 male, 1 female

2. polygyny: 1 male, more than or 2 females

3. polyandry: more than or 2 males, 1 female

4. polygynandry: more than or 2 males, more than or 2 females

battle of the sexes

males and females have conflicting evolutionary interests over mating — males prefer to mate with as many females as possible — females concerned about critical resources needed for reproduction (ex: food, nest sites, space, quality of mates) 

3 principles for variations in mating systems 

1. environmental conditions limit the number of mates that males can obtain

2. environmental conditions limit the ability of males to monopolize mates

3. when males cannot monopolize mates, females can choose their mates or the number of mates

2 types of monogamy in mammals

1. facultative

2. obligate

facultative monogamy

WEAK pair bond, poorly developed parental care, mates only co-occur for breeding

obligate monogamy

STRONG pair bond, well developed parental care, frequent co-occurrence of mates

lek

dominance hierarchies on a display ground formed by males — females gather to choose mates

3 reasons to form groups

1. aggregate on common resource — food, breeding sites

2. group foraging — ex: lions and wolves

3. defense against predators — ex: ground squirrels

4 mechanisms of defense against predators

1. geometry for the selfish herd — minimize the domain of danger (organisms form into a shape)

2. dilution effect — random chance of predation (ex: 1/3 in small group but 1/6 in large group)

3. detection — ground squirrels and meerkats

4. defense — species like muskox forming a defensive ring