Summary Behavioural Ecology (BHE-30306)

Behavioural Ecology
Study of the evolution basis for animal behaviour due to ecological pressures
 Ethology (behaviour)
 Ecology (environment)
 Evolutionary biology (gene transfer)


Chapter 1
Natural selection favours individuals who adopt life-history strategies that maximise their gene
contribution to future generations

Plasticity: one can adapt to environment

Chapter 3
Behaviour involves decision making (where to
search, what to eat) which has costs as well as
benefits

Reproduction / survival model 
 Investment in reproduction increases, than
births increases
 However individual survival decreases,
because it invests into offspring




Longer mating constraint re-mating with other
individuals (= more costs) while diminishing returns
(= lower benefits)

,Chapter 2
A rigorous scientific approach to understand the function of behaviour, which involves four stages:
observations, hypotheses, predictions and tests

Tinbergen’s 4 why’s
 Proximate
o Causation/mechanism
 Sight, sound, hormone
o Development/ontogeny
 Genetic, developmental mechanism
 Ultimate
o Function (Survival value)
 Adaptive advantage
o Evolutionary value (phylogeny)
 Way it is evolved

Correlation does not mean causation

Experiment
 Vary variable of interest
 Critical concepts
o Variable manipulated by experimenter
o Test against control group
o Random assignment of individuals to conditions
o Avoid confounding variables
o Suitable sample size
Natural experiment
 Conditions are determined by nature of other factors outside the control of the
experimenters

Comparative study
 Differences between species
 Make broad inferences and predictions about adaptations and evolutionary change

Behavioural ecology studies are built upon
 Clever hypotheses and predictions from models
 Correlations, experiments and comparative studies



Mating systems
Individuals aim to maximise reproductive success

Systems
 Monogamy
o Also extra-pair copulation
 When one of these individuals mates outside of this pairing
o Bi-parental care
 Polygyny
o Males copulating with multiple females
o Female-only care

,  Polyandry
o Female copulating with multiple males
o Male-only care

Sperm is cheap, eggs are expensive, therefore males can fertilise many females

90% of birds are monogamous, while only 5% of the mammals
 In birds species cooperation is needed to raise the offspring
o One protect, one search for food
 In mammals the offspring is lactating, so only female is needed

Main factors defining mating systems
 Dispersion of individuals and food
o Female fitness depends on resources
o Male fitness depends on access to females
o Mating systems is influenced by distribution of females in time and space
o Male strategies
 Defend females
 Follow females
 Defend territorial where females will pass
 Gather with multiple males and attract females (LEKS)
 Sexual conflict
o Cost and benefit of parental care
o Differences between
 Monogamy
 Polygamy

Extra-pair mating in birds
 Costs
o No parental care of male when cuckolded
o Harassment and aggression of conspecifics
o Risk for disease or danger
o However, it is initiated by females
 Benefits
o Males: obtain more offspring
o Female: good genes, fertility insurance (inbreeding avoidance)
 Extra-pair mating is primarily determined by phylogeny
o Explains about 55% of variation
 Access to multiple territories seems to increase extra-pair mating
 Females with a related male seem to increase extra-pair mating