16.1 - Predator-Prey Dynamics

predator-prey interactions

form of species interactions where 1 species eats another species

best strategy for predators

maximises their ability to capture and consume prey

• strength and swiftness - actively search for and capture high quality prey e.g. fox and duck

• ability to look inconspicuous so stealth predators to ambush prey when prey passes e.g. wide mouth frog 

best strategy for prey

minimises likelihood of being eaten

• escape by flying or running

• morphological defences

• avoiding detection

• chemical defences

• warning signals

• mimicry systems

• behavioural mechanisms

avoiding detection

camouflage - species resemble objects that their predators consider inedible = not seen by predators

morphological defences

physical adaptations that protect prey e.g. touch skin, shell, spines 

chemical defences

generally used by prey that’s small, weak or immobile to deter predators through toxic substances or distasteful chemicals. Some predators when they ingest their prey’s defence chemicals and use them for own predators

e,g, of predator chemical defence

poisonous dart frog sequesters toxins from their prey (ants and mites). Frogs store these toxins in brightly coloured skin on bacjs and use as defence

warning signals

visual or auditory cues used by prey to indicate toxicity or unpalatability to potential predators, often resulting in avoidance.

mimicry systems

adaptations where one species resembles another to gain a survival advantage - Batesian and Müllerian

behavioural mechanisms

strategies like group flocking and alarm vocalisation - animals that live in groups spread the cost of looking out for predators

e.g. more pigeons in flock = sooner hawk is spotted - lower hawk success 

How do predator-prey cycles arise?

interdependent population dynamics between predators and their prey -when prey increase = predators have more food so they increase. When predator increase they eat more = prey declines. Fewer prey = predators decline = prey can recover - cycle repeats