Community Ecology Chapter 54 Community Interspecific interactions v

Community Ecology Chapter 54

Community Interspecific interactions v Interactions with different species v Competition v Predation v Herbivory v Symbiosis v

Interspecific Competition Two species compete for resources v Competitive exclusion: v One species utilizes resources more efficiently v Eliminates the other v

Paramecium

Niche Species use of resources in its environment v Abiotic & biotic v Fundamental niche: v Area that a species is capable of utilizing v Realized niche: v Actual resources the species utilizes v

Resource Partitioning Species use similar niches v Subdivide available resources v Warbles (small bird)-spruce trees v Lizards in Dominican republic v Character displacement: v Sympatric species diverge more than allopatric species v

Barnacles

Resource partitioning

Predation v Consuming of one organism by another

Predators

Animal defenses Hide or run v Chemicals (bees, wasps, scorpions, spiders) v Snakes, lizards, frogs v Coloration v Aposematic: warning v Cryptic: blending v

Aposematic

Cryptic

Animal defenses Mimicry v Batesian: v Harmless animals mimic harmful animals v Mullerian: v Several harmful animals look the same (safety in numbers) v

Batesian mimicry

Mullerian mimicry

(a) Mechanical defense (b) Chemical defense ▶ Porcupine ▶ Skunk (c) Aposematic coloration: warning coloration (d) Cryptic coloration: camouflage ◀ Poison dart frog (e) Batesian mimicry: A harmless species mimics a harmful one. ▶ Canyon tree frog (f) Müllerian mimicry: Two unpalatable species mimic each other. ▲ Venomous green parrot snake ◀ Nonvenomous hawkmoth larva ◀ Yellow jacket ◀ Cuckoo bee

Mimic octpus (a) Mimicking a sea snake (b) Mimicking a flounder (c) Mimicking a stingray

Herbivory Organism eats part of a plant v Thorns, spines, prickles v Chemicals v Mustard oils, milkweed, nicotine v

herbivore

Symbiosis v v v v 2 or more organisms interact in a permanent relationship Lichen Mycorrhizae Types of symbiosis Commensalism Mutualism Parasitism

Commensalism Interaction benefits one organism v But neither harms nor helps the other v Fish & sea anemones v Egrets & cattle v

Commensalism

Commensalism

commensalism

Mutualism Interactions benefit both species v Flowers and bees, birds or bats v Ants and acacias (plant) v

Mutualism

mutualism

Mutualism

Parasitism One organism benefits at the cost of its host organism v Parasite is usually smaller than host v Ectoparasites (external) v Ticks. lice v Endoparasites (internal) v Tapeworms v

Parasitism

Community structure v v v How these interspecific interactions work all together 1. Predation reduces competition 2. Parasitism vs competition 3. Indirect effects (rodents and ants) 4. Keystone species Species that has a strong effect on the composition of a community

Keystone species

Succession Communities change from simple to complex over time v Secondary succession: v New community arises where an old community was disturbed v Primary succession: v New community arises on bare lifeless substrate (glacier receding) v

Primary succession

Secondary succession