Chapter 14: Interactions in the Ecosystem

Niche versus Habit? Habitat Habitat – describes all of the abiotic and biotic factors in the area where an organism lives Niche Niche – All the biotic and abiotic factors that a species will need to survive and reproduce Includes – Food – Abiotic conditions – Behavior

Habitat versus Niche

What kind of interactions can organisms in the same community have ? Think of how you interact with people you know. What kind of interactions are they? Friendship Competitor Enemy No relationship

1.Competition – Two organisms fight for the same limited resources Food Space Mates Oxygen and Sunlight Community Interactions

2.PredatorPreyRelationship 2.Predator – Prey Relationship – One species captures and feed on another – What happens when the prey population increases to the predator population? – What happens when the predator population increases to the prey population? The two are directly proportional to each other It increases also It decreases and then the prey decrease

3.Symbiosis – Close relationship between two or more organisms of different species which interact with each other

a)Mutualism – Both benefit from the interaction

b)Commensalism – One organism benefits from the relationship and the other is unharmed

c)Parasitism – One organism benefits and the other is harmed

Carrying Capacity Is the maximum number of individuals of a particular species which the environment could support When year did the population first reach carrying capacity? What is the carrying capacity for this population size? What is your prediction for population size immediately following WWII? ~1850 ~1.6 million people It will decrease

What ecological factors limit population growth? 1.Density- Dependent limiting factors – Limiting factors that are affected by the population’s size Competition – limited resources causes a struggle for survival (Darwin!!) Predation Predation – as the predator’s population increases, the prey population decreases Parasitism and disease Parasitism and disease – the three things that control a population’s size are war, disease and famine!! (Malthus!!)

2.Density – Independent limiting factors – Factors in the environment that limits a population’s growth that have nothing to do with the size of the population Weather Natural disasters Human activity

Density dependent or density independent factors? 1.Competition between members of population. 2.Predation. 3.A hurricane drowning many earthworms 1.Disease 2.Burning of a forest 3.A very cold winter Density Dependent Density Independent

What follows the Natural Disaster? Succession Succession – A sequence of biotic changes that regenerates a damaged community or a bare, new area – What follows a forest fire? – What happens after a volcano? – What occurred after the asteroid hit the earth?

Primary Succession bare rock Primary Succession starts from bare rock Pioneer species are the first to inhabit the area – Lichens and mosses Break down minerals in rock to allow for soil to build up Soil gets thicker and now grasses can start to grow. Next comes small shrubs then trees CLIMAX community Final community is the CLIMAX community which are large trees like Oaks and Pines

Pioneer species Climax species

Usually occurs in areas that have been disturbed – Bulldozed or cleared area – Fire – Flood – Hurricane Secondary Succession Secondary Succession starts from soil

Pioneer species Climax species