Types of interaction

In ecosystems

Interspecific Interactions

• Competition

• Predation

• Herbivory (herbivores eating plants or algae)

• Symbiosis

Competition

• Interspecific – between species

• Competitive Exclusion – local extinction of a population due to direct competition for resources with another species – Example – Barnacles

Competition

• Resource partitioning – differentiation in niches that allows similar species to coexist in a community– Examples

• Warbler species (p. 76 in text) – all feed in different parts of pine tree

• Different species of lizards have different feeding habitats in the same area

Predation

• Predator – kills and eats another

• Prey – the hunted (eaten by the predator)

• They both make adaptations to eat and avoid being eaten through natural selection

Adaptations of Predators

• Acute sense of smell• Claws• Teeth• Fangs• Stingers• Poison• Predators are usually fast or are

camouflaged

Defenses against predation(adaptations of prey)

• Camouflage• Mechanical defenses• Chemical Defenses• Mimicry

– Batesian – a harmless species mimics an unpalatable or harmful model

–Mullerian – two unpalatabel species that inhabit the same community mimic each other.

Camouflage

• Grey tree frog and moth

Mechanical Defenses

• Porcupine’s sharp quills

Chemical Defenses

• Poison Arrow frog

Mimicry

• http://waynesword.palomar.edu/lmexe10b.htm#mimicry

• Batesian – example a snake and a hawkmoth larva

• Mullerian mimicry – example – cuckoo bee and a yellow jacket

• Look up your own adaptations – Bring it in for class tomorrow!!

Keystone Species/Predator

• A species that exerts strong control on community structure because of its ecological role or niche

• Thus, they reduce the number of the strongest competitors in the community, preventing competitive exclusion of weaker competitors

• Examples– Sea Star– Sea otter

Generalized vs. Specialized Species

• Generalized species – eats a variety of food

• Specialized species – eats one or two species only

• What is the advantage to a keystone predator of being specialized to feed mainly on those prey species that are otherwise the most successful amount potential prey species?

Answer

• The most competitive prey species probably represent the most abundant and dependable food source for the predator

Herbivory (herbivores eating plants or algae)

• Plant adaptations to avoid being eaten:

– Chemical toxins• Morphine, nicotine, mescaline, tannins, cinnamon,

cloves, mint

– Spines or thorns

Symbiosis

• Symbiotic Relationship is one between two or more species that live together in direct contact.

• Three Types– Parasitism– Commensalism– Mutualism

Parasitism

• A parasite lives on or inside host and obtains nourishment from the host

• One partner benefits while the other is harmed.

• Examples: tapeworms, ticks, pathogens (microscopic parasites)

Commensalism

• One partner benefits without harming the other

• Examples: algae on sea turtles, barnacles on whales, and birds that feed on insects flushed out by grazing cattle

Mutualism

• Benefits both partners in the relationship

• Examples: – Acacia Tree and ants