1.2 Interdependence All species rely on many others for

survival

Symbiosis – The relationship between individuals of two different species over time.

Types of Symbiosis Commensalism – one organism

benefits while the other is unaffected.– Barnacles attach to a whale to move to

other areas…the whale is unaffected.

Mutualism – both species benefit– Cow birds sit on backs of cows and eat

the bugs off them…the birds get food while the cows get cleaned.

Parasitism – one organism benefits while the other is harmed.– Tapeworm attaches to the intestines of a

human. The tapeworm gets nutrients from food in intestine, leaving little food for the human.

Symbiotic relationships are examples of extreme interdependence.

Predator/Prey relationships are also a form of interdependence!!– E.g. Lynx and Hare

Niches – role of an organism in an ecosystem

Interspecies competition – when two or more species need (compete for) the same resource.

This is one type of interaction between species where neither species benefits.– E.g. two species competing for the same

food source will both have less food=starvation in the population.

COMPETITION

Interspecies competition puts limits in the size a certain population will be.

So How do so many species exist together in the same place?

They all have specific NICHES!!!– What it eats, what eats it, its habitat,

nesting site, range(how far does it roam), its effect on populations around it and its environment…

Niches vary from population to population.– The niche a population occupies may

change over time. E.g. frog tadpole – aquatic environment

– Adult Frog – aquatic AND terrestrial environment

Resource Partitioning

Division of a resource among two or more coexisting species so that the niche of each species differs slightly.

Homework

Page 19 Questions 1,2,3,4