Community Ecology Chapter 54

Community Interspecific interactions Interactions with different species Competition Predation Herbivory Symbiosis

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

Paramecium

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

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

Barnacles

Resource partitioning

Predation Consuming of one organism by another

Predators

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

Aposematic

Cryptic

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

Batesian mimicry

Mullerian mimicry

(a) Mechanical defense (b) Chemical defense ▶ Porcupine ▶ Skunk (c) Aposematic coloration: warning coloration (d) Cryptic coloration: camouflage ◀ Poison dart frog ▶ Canyon tree frog (e) Batesian mimicry: A harmless species mimics a harmful one. (f) Müllerian mimicry: Two unpalatable species mimic each other. Figure 54.5 Examples of defensive adaptations in animals ▲ Venomous green parrot snake ◀ Yellow jacket ◀ Nonvenomous hawkmoth larva ◀ Cuckoo bee

(a) Mimicking a sea snake Mimic octpus (a) Mimicking a sea snake (b) Mimicking a flounder Figure 54.6 The mimic octopus (c) Mimicking a stingray

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

herbivore Figure 54.7 A West Indian manatee (Trichechus manatus) in Florida

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

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

Commensalism

Commensalism

commensalism Figure 54.9 A possible example of commensalism between cattle egrets and African buffalo

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

Mutualism

mutualism Figure 54.UN08 Test your understanding, question 14 (interspecific interactions)

Mutualism

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

Parasitism

Community structure 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 Secondary succession: New community arises where an old community was disturbed Primary succession: New community arises on bare lifeless substrate (glacier receding)

Primary succession

Secondary succession