Lecture 4 - Feeding, foraging, anti-predatory behaviours

broad groups of species

generalists = humans ie have teeth that will shear, bite & grind and so our dentition tells us we should have a broad diet

specialists = pandas ie herbivores which is weird from evolutionary perspective as they are a bear (carnivore). clumsy as energy intake from bamboo is low

differing volume of food consumed

selector = selects specific parts of food for nutritious content ie giraffes

bulk feeder = quantity over quality ie elephants

differing basal metabolic rate (BMR)

high - means need to meet demand regularly

low - means they have a lower energy demand

differing conformity

some conform to prevailing conditions ie frog, ectothermic

some are regulators and have precise control over internal physiology ie brown bears, endothermic

choosing food by colour

- red & black (common); highly conspicuous but does not indicate nutritional content

- less common fruit colours indicate nutritional content; proteins, carbohydrates

what not to eat

- avoid sickness inducing foods

- generalists may encounter different food types so may be unaware if food is sickness inducing

- specialists have no facultative response

optimal foraging theory

trade-off between energy gain & expenditure

- larger item = more energy available, more cost in time/energy to find/process

- ie crabs the time to process mussel shells takes long but they gain more energy

primary defences

reduce probability of an attack. examples

- remaining hidden (being inconspicuous)

- pretending to be dangerous (mimicry)

- reducing selection off (group living, dilution effect)

forms of mimicry

1. mullerian = honest signals where phenotype is true reflection of internal characteristics (monarch butterfly)

2. batesian = dishonest signal ie milk snake

group benefits

- dilution

- confusion

- selfish herding

- vigilance

should join a group of an optimum size to maximise investment in the group 'deal'

secondary defences

reduce likelihood of a successful attack

- distraction

- alarm calls

- mobbing

- showing off