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
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
