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Ecology Chapter 10: social behaviors

Terms in this set (38)

Social behaviors
Interactions with members of one's own species
Social behaviors have a _________ ________ & are
subject to ____________ ____________
genetic basis; natural selection
Selection has favored what social behaviors?
cohesive groups &
constrained antagonism
example of Other organisms than animals exhibit social
"behaviors"
- Bacteria & protists secrete chemicals to sense each other to react in "friendly" or "aggressive" ways
- damaged plants emit volatile chemicals that warn other plants
Group benefits
Dilution effect:
Lek:
Many individuals searching for food may be able to find rare food
more easily
Dilution effect
Reduced probability of predation to a single animal when in a group
More individuals watching for predators ---> each individual spends less time watching & more time feeding
lek
Location of an aggregation displaying
males that attract the opposite sex
lek example
Larger leks of ruffs attract more females
resulting in an increased probability of
successful copulations
Group costs
- Groups of animals are more conspicuous to predators
- The risk of parasitic infection increases in groups
High densities can increase the rate at which diseases spread
-food must be shared
Territory:
- Area defended by one or more individuals against the intrusion of others
- can be temporary or relatively permanent
Dominance hierarchy:
Social ranking among individuals in a group, typically determined
through contests such as fighting, displays, or contests over food
dominance hierarchy occurs when
species density is relatively high & not feasible to defend resources against all conspecifics
Donor:
Individual who directs a behavior toward another individual
Recipient:
individual who receives the behavior of a donor
Every interaction between 2 individuals has the potential to affect the fitness of
both individuals; positively or negatively
Cooperation:
Donor & recipient of a social behavior both experience increased fitness from interaction (e.g., pride of lions kill prey)
Selfishness
Donor experiences increased fitness & recipient experiences
decreased fitness (e.g., competition for food)
Spitefulness:
Social interaction reduces the fitness of
both donor & recipient (does not occur in
natural populations?)
Altruism:
Social interaction increases recipient
fitness & decreases the fitness of the
donor (rare or does not occur in nature)
Direct fitness:
Fitness gained by parents passing on copies of genes to offspring
Indirect fitness:
Fitness an individual gains by helping relatives (donor & recipient
have shared genes) pass on copies of their genes
Inclusive fitness:
Direct fitness + indirect fitness
Direct selection
Selection that favors direct fitness
Kin selection (indirect selection)
selection favoring indirect fitness
apparent altruism example
Example:
Male turkeys display to females alone or
in a coalition
When a coalition displays, only the
dominant male gets copulations
Cooperative Breeding
Helping non‐offspring appears to be altruistic
Helpers benefit others while incurring costs
- some mammals and birds
Eusocial animals
1. Adults living together in a group
2. Overlapping generations of parents and offspring
3. Cooperation in nest building & brood care
4. Reproductive dominance by one or a few individuals & presence
of sterile individuals
examples of eusocial animals
Insects, snapping shrimp, naked mole rat & Damaraland mole rat
Caste:
Individuals within a social group - have a specialized form of behavior
Ants, bees, and wasps sons and daughters of queen
Sons = unfertilized eggs; daughters = fertilized eggs (haplodiploid)
sex determination system of Ants, bees, and wasps
one sex is haploid & other is diploid
Nonreproductive progeny of a queen
gather food & care for young
Termite colonies
massive structures dominated by a mated
pair (king & queen)
King & Queen termites offspring production
- produce sons & daughters by sexual reproduction; both serve as workers.
- Offspring remain sexually immature unless the king or queen dies
Mole rats reproduction
Single queen & several kings are responsible for all reproduction
Dominant female mole rat strategey
Dominant female harasses
offspring to increase stress, decrease sex hormones , & makes workers
less motivated to breed
Being haplodiploid favors...
the evolution eusociality; but not required
Eusocial behavior can evolve if...
the cost of leaving a colony is high due
low survival (constraints)
THIS SET IS OFTEN IN FOLDERS WITH...