Asking questions and testing hypotheses in animal behaviour Flashcards
Natural selection. Definition.
It’s the name for consistent difference in offspring production by different classes of reproducing entities, either phenotipically different organisms or genes. This leads to adaptation.
Adaptation
Adaptation is the evolutionary process whereby an organism becomes better able to live in its habitat or habitats. Increases fitness.
Evolution
is the change in frequency of heritable variants from generation to generation.
Tinbergen’s four questions about behaviour. (4)
- Adaptive function. Current function / utility in nature - Evolution. Evolutionary history - Immediate causation. What triggers the behaviour? physiological processes - Ontogeny. How does it develop? genetic, experience & developmental processes
Say if it is proximate or ultimate.
ultimate ultimate proximate proximate ultimate proximate or ultimate proximate ultimate
How do ants build the bivouac? prox/ult?
Ants link together using their feet. Proximate
What is the adaptive function of building bivouacs? prox/ult?
Bivouacs stabilise temperature and humidity. Ultimate
Why build bivouacs instead of permanent nests?
Army ants have many larvae to feed. Temporary nests allow them to move regularly with the larvae to find new food sources. Ultimate
Black headed gulls (Schwarzkopfmöwe) leave the nest undefended to take eggshells away. What is the function/ adaptive value of this behavious?
Eggshell removal reduces predation.
Optimality
Optimality is defined as the point where the difference between benefits and costs for a behavior is maximized, which can be done by graphing the benefits and costs on the y-axis and a measure of the behavior on the x-axis.
Optimality and natural selection
Natural selection leads to adaptations that maximise fitness benefits in relation to fitness costs.
Parental survival is affected by clutch size(amount of eggs laid). Yes/No?
Yes.
Enlarged clutch size decreases parental survival. Yes/No?
Yes.
What is the Comparative approach?
Phylogenetic comparative methods (PCMs) use information on the historical relationships of lineages (phylogenies) to test evolutionary hypotheses.
Asking proper questions. (4)
- Question - Hypothesis - Null hypothesis - Prediction
Null hypothesis. When do we accept/reject it?
We reject the null hypothesis if the probability of obtaining the results in the sample when the null hypothesis is true is less than 5%.
Null hypothesis testing
- Assume for the moment that the null hypothesis is true, and there is no relationship between the variables in the population. - Determine how likely the sample relationship
Null hypothesis testing (3)
- Assume for the moment that the null hypothesis is true, and there is no relationship between the variables in the population. - Determine how likely the sample relationship would be if the null hypothesis were true. Need statistics! - If the sample relationship would be extremely unlikely, then reject the null hypothesis. If it would not be extremely unlikely, then retain the null hypothesis.
Drawbacks of the null hypothesis. (2)
-5% false positives is a lot! (rejecting the null hypothesis when it is true) - the larger the sample the likelier it is to find a difference from zero
What kind of evidence do we use for hypothesis testing? (3)
- Correlations - Experiments - Models
Correlations is the same as Causation. Yes/No
NO! Correlation is not the same as Causation! Be careful!
Experiments to test causality. Explain
Test the effect of X on Y. Manipulate only one variable (X), keeping everything else as equal as possible. - need appropriate treatment groups and controls - Random allocation by experimenter to treatment or control group - Avoid experimenter prejudice/bias
