Chapter 14: Interactions in the Ecosystem

Niche versus Habit? Habitat Niche Includes Food Abiotic conditions describes all of the abiotic and biotic factors in the area where an organism lives 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

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

It decreases and then the prey decrease 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

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

Mutualism Both benefit from the interaction

Commensalism One organism benefits from the relationship and the other is unharmed

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

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

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

What follows the Natural Disaster? 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 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 Final community is the CLIMAX community which are large trees like Oaks and Pines

Climax species Pioneer species

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

Climax species Pioneer species