Species interactions Symbiosis

Symbiosis Symbiosis is the term used to describe close interactions between two or more different species

Species interactions can be described as either Interspecific Eg.Competition between members of different species for resources such as food,etc. This is usually less intense Remember Gause’s competitive exclusion principle! Intraspecific eg. competition between members of the same species for resources such as food, breeding sites , territories etc. This is usually intense.

Exploitation Predation- predators and prey One species benefits at the expense of another it can be divided into:- Predation- predators and prey Herbivory- animals eat or graze on plants Parasitism- Ecto parasites live outside the hosts body. Endo parasites live inside the hosts body.

Predator / Prey interactions predators and prey often regulate each others populations. They often mirror each other when there is not much prey swapping. When there are lots of hares , there are lots of lynx.

Herbivory The cows benefit and the grass suffers harm. Animals eat plants as primary consumers The cows benefit and the grass suffers harm.

Parasitism One organism benefits and the other one suffers The body louse gets food protection, warmth and the human suffers with itchy bites blood loss and feeling lousy!

competition Two species compete for the same resources. Both organisms suffer. Hyena and lions both compete for the wildebeast

Mutualism Both organisms benefit The zebra gets ticks eaten off it skin and the Oxpecker gets a free ride and dinner!

Commensalism One organism benefits whilst the other is not effected The cattle churn up the mud and the egret benefits because it uncovers insects which it can eat.

Amensalism One organism suffers harm and the other organism is not affected Water birds trample and kill vegetation around the ponds edge

Antibiosis – a special type of amensalism One organism is unaffected but the other is killed or harmed by chemical secretions

A food chain shown which way the energy flows

Food webs and food chains are arranged in trophic levels

the amount of Energy decreases with each tropic level so there are always less predators than prey