Predation Muzvondiwa J.V.

Outline There are a variety of antipredator adaptations, which suggests that predation is important in nature Predator–prey models can explain many outcomes Field data suggests that predators have a large impact on prey populations

Outline Experiments involving the removal or introduction of exotic predators provide good data on the effects of predators on their prey Field experiments involving the manipulations of native populations show predation to be a strong force

Predation Traditional view: carnivory Differences from herbivory Herbivory is nonlethal Differences from parasitism In parasitism, one individual is utilized for the development of more than one parasite Predator–prey associations

Antipredator Adaptations

Aposematic or warning coloration Advertises an unpalatable taste Ex. Blue jays and monarch butterflies Caterpillar obtains poison from milkweed Blue jays suffer violent vomiting from ingesting caterpillar Ex. Tropical frogs Toxic skin poisons

Camouflage Blending of organism into background color Ex. Grasshoppers Ex. Stick insects mimic twigs and branches Ex. Zebra stripes: blend into grassy background

Mimicry Animals that mimic other animals Ex. Some hoverflies mimic wasps

Types of mimicry Müllerian mimicry – Fritz Müller, 1879 – Unpalatable species converge to look the same Reinforce basic distasteful design Ex. Wasps and some butterflies Mimicry ring: a group of sympatric species, often different taxa, share a common warning pattern Batesian mimicry – Henry Bates, 1862 – Mimicry of unpalatable species by palatable species Ex. hoverflies resemble stinging bees and wasps

Displays of intimidation Ex. Toads swallow air to make themselves appear larger Ex. Frilled lizards extend their collars to produce the same effect

Polymorphism Two or more discrete forms in the same population Color polymorphism – Predator has a preference (usually the more abundant form) – Prey can proliferate in the rarer form – Ex. leafhopper nymphs (orange and black) – Ex. Pea aphids (red and green) Reflexive selection – Every individual is slightly different – Examples: brittle stars, butterflies, moths, echinoderms, and gastropods – Thwart predators’ learning processes

Prey phenologically separated from predator Ex. Fruit bats – Either diurnal or nocturnal – Only nocturnal in the presence of predatory diurnal eagles

Chemical defense Used to ward off predators Ex. Bombardier beetles – Possess a reservoir of hydroquinone and hydrogen peroxide – When threatened, eject chemicals into "explosion chamber" – Mix with peroxidase enzyme – Mixture is violently sprayed at attacker

Masting Synchronous production of many progeny by all individuals in population Satiate predators Allows for some progeny to survive Common to seed herbivory