A6 Ethology Flashcards
Define ethology.
The scientific study of animal behaviour under natural conditions (i.e. observational not experimental).
What are the main principles of ethology?
- Natural selection can change the frequency of an observed animal behaviour.
- Behaviour that increases the likelihood of survival and reproduction will become more prevalent in a population.
- Learned behaviour can be spread through a population or be lost from it entirely more rapidly than innate behaviour.
Give an example of how learned behaviour can be lost from a population.
At the start of the 20th century, blue tits would feed on cream from milk bottles. They learnt how to penetrate the foil lids and siphon cream. The ability to pierce the seals and siphon the cream has since been lost from the blue tit population as milk is no longer delivered and is now capped with a plastic lid so the situational context is no longer present.
Give an example of how natural selection can affect animal migratory behaviour.
Blackcap birds breed during summer in Germany and historically have migrated to Spain for winter. However as global temperatures have increased the migratory patterns of blackcaps have changed due to natural selection. Some blackcaps now migrate to the UK for winter as survival rates have improved there because of the warmer temperatures.
Define altruism.
Behaviour which benefits another individual at the cost of the performer. It reduces the potential for the altruistic individual passing on their genes. However, it improves the chances of the other individual passing on genes into the same gene pool.
What are the types of altruism?
Kin selection: Enhancing the reproductive success of relatives who share common genes.
Reciprocal altruism: Organisms that live in social clusters will also promote the conservation of altruistic genes.
Describe a type of altruism in nature.
Vampire bats commonly regurgitate blood to share with unlucky roost mates who were unable to gain independent sustenance. They cannot survive multiple successive days without food and food can often be difficult to find. The small cost of sharing blood (lost time until starvation) is less than the benefit received (time gained). Hence sharing blood improves the fitness of the entire brood (via reciprocal altruism), increasing the occurrence of altruism.
Define foraging.
The act of searching for (and potentially finding) food resources in nature.
Describe the optimal foraging strategy.
Animals will adopt strategies that:
- Minimise the cost of foraging (i.e. the amount of energy used to capture and consume prey).
- Maximise the benefits to the consumer (i.e. the amount of energy yielded by a particular food source).
How do shore crabs demonstrate optimal foraging?
Shore crabs demonstrate selectivity in the type of mussel foraged when the mussel population is abundant. They will ignore smaller mussels (as the energy yield is less than that obtained from larger mussels) and larger mussels (difficult to crush, also risks potential damage to the crab’s claws). Instead they will selectively identify and feed on mid-sized mussels (provided the mussel supply is in abundance).
How do breeding strategies in Coho salmon demonstrate how behaviour affects survival and reproduction?
Male coho salmon form two different breeding populations, jacks or hooknoses. They employ different breeding strategies in order to successfully reproduce with female coho salmon.
- Jacks sneak out from and attempt to stealthily mate with a female.
- Hooknoses swim within the open water and fight aggressively amongst one another for the opportunity to mate.
Having two breeding pathways improves the rates of successful reproduction and also increases levels of genetic variation.
Define courtship.
A set of behavioural patterns whereby potential mates inform each other of a readiness to reproduce.
Describe how courtship in birds is an example of mate selection.
Whereas females appear drab, male birds of paradise will have bright plumage and display fancy behaviours to demonstrate their virility. While these features make them a target for predators, they improve chances of attracting female attention (mate selection). Any exaggerated trait that improves reproductive fitness will become more prominent in future generations (sexual selection).
Describe how synchronised oestrus in female lions is an example of innate behaviour increasing survival and reproduction of offspring.
Male lions leave their birth group at a young age and in order to reproduce must replace males in existing prides. Upon establishing dominance within a pride, a male lion will kill all cubs already present.
The loss of cubs triggers an innate, synchronised response whereby all lionesses enter a period of oestrus. This increases the number of offspring the male lion can produce,
allows for shared lactation and nursing of cubs within the pride and makes it easier for the lionesses to hunt and defend the pride as all cubs are of a comparable age.
