Species Interactions Section 2-1

Species Interactions Species within a community develop close interactions, known as symbiosis. –“Sym” means together –“Bio” means life –Symbiosis means “living together” and describes the close relationships developed between species. Symbiotic relationships will always benefit at least one organism involved.

Species Interactions There are 5 major types of symbiotic relationships: –Predation –Parasitism –Competition –Mutualism –Commensalism

Predation Predation is a relationship where one organism captures and consumes another. –Predator – organism doing the capturing –Prey – organism being captured A predator’s survival depends on its ability to catch its prey. –Ex: rattlesnake venom, spider web, etc. A prey’s survival depends on its ability to avoid being caught. –Camouflage, mimicry, physical/chemical defenses

Prey Defenses Mimicry – a defense where one organism resembles another that is dangerous or poisonous There are two types of mimicry: –A harmless organism closely resembles a dangerous one Known as Batesian mimicry Predators learn to avoid both species Ex: King snake and coral snake –Two harmful organisms resemble one another Known as Mullerian mimicry Added advantage to their already harmful adaptations Ex: Bees and wasps have similar striping

Prey Defenses Plants have also developed adaptations to protect them from predators. –Physical defenses make them difficult to eat Ex: Spines, thorns, tough leaves –Can produce secondary compounds Secondary compounds are synthesized from products of the plant’s metabolism Usually poisonous, irritating, or bad-tasting Ex: Poision ivy and poison oak

Parasitism Parasitism – symbiotic relationship where one organism is harmed and the other is helped –Parasite feeds on the host organism –Unlike predation, it does not result in the immediate death of the host Ex: tapeworms can live in human digestive tract for long periods of time

Parasitism There are 2 different types of parasites: –Ectoparasites External parasites – live on the outside of the host Ex: ticks, fleas, mosquitoes –Endoparasites Internal parasites – live inside the host’s body Ex: bacteria, protists, tapeworms

Competition Competition – the use of the same limited resource by two or more species in the same place at the same time –Resource = anything necessity of life (water, nutrients, light, food, or space) Competition may cause the development of different niches or physical characteristics.

Competition Competitive Exclusion Principle –No two species can occupy the same niche in the same habitat at the same time –Ex: Paramecia Two species of paramecia will thrive separately, but when put together, one species is eliminated

Competition Organisms may develop physical differences because of competition for resources. Character Displacement – evolution of anatomical differences that reduces competition –Happens most where ranges of competitors overlap –Ex: Darwin’s finches Species found in separate locations have the same beak size The same species found together have different beak sizes –allows them to feed on different seeds and reduces competition

Competition Organisms may develop differences in niches because of competition for resources. Resource Partitioning – species coexist by using only part of the available resources –Ex: some birds eat the same insects, but hunt for them in different places

Mutualism Mutualism is a symbiotic relationship where both organisms are helped in some way. Ex: Plants and their pollinators –Pollinators feed on the plants and pollen gets stuck to them. –Pollen is deposited on the next plant, allowing the plants to reproduce sexually.

Commensalism Commensalism is a symbiotic relationship where one organism benefits and the second is neither harmed nor helped. Ex: Clownfish and sea anemone –The clownfish uses the anemone as shelter –The anemone receives no benefit, but is not harmed either –animationanimation

Name the Symbiotic Relationship… A eagle hunting a mouse. –Predation A tick feeds on the blood of its host and may carry disease –Parasitism The flower lives on a tree and absorbs the water from runoff and the tree is unaffected. –Commensalism Two different types of finches feeding on seeds. –Competition An ant protects a caterpillar from predators and the caterpillar produces a sweet liquid for it to drink. –Mutualism