Living Things in Ecosystems

Everything is connected…

What is an Ecosystem? Includes all the different organisms living in a certain area, along with their physical environment Biotic Factors – the living parts of an ecosystem The animals, plants and microorganisms Abiotic Factors – the nonliving parts of the ecosystem Temperature, sunlight, water, soil, etc.

Levels of Organization Organism – one individual living thing Species – a group of organisms that are able to produce fertile offspring Population – a group of individuals of the same species living the same place Community – a group of interacting populations of different species

Levels of Organization

Niche and Habitat Habitat – the actual place where an organism lives Lion – savanna Cactus - desert Niche – an organism’s way of life When and how often an organism reproduces What time of day it’s most active What it eats and what eats it

Evolution by Natural Selection Charles Darwin proposed his theory of natural selection to explain how organisms adapt to their environment Natural selection – the unequal survival & reproduction that results from the presence or absence of certain traits Evolution – the change in the traits of populations from one generation to the next

Evolution by Natural Selection

Darwin’s Theory All organisms produce more offspring than can possibly survive The environment contains things that kill organisms (struggle to survive) Individuals vary, or differ, in their traits Some variations give an organism an advantage Those with advantages survive and have more offspring

Evolution by Natural Selection

Coevolution When two or more species evolve in response to each other Snails developed thicker shells, so crabs evolved stronger claws Plants produce poisonous chemicals, herbivores evolved the ability to detoxify these chemicals

Adaptation An inherited trait that increases an organism’s chance of survival and reproduction in a certain environment.

Artificial Selection The selective breeding of organisms by humans for specific characteristics. Fruits, grains and veggies too = shape, size, sweetness, visual appeal

Resistance The ability of one or more organisms to tolerate a particular chemical designed to kill it. Bacteria Insects Humans, etc.

Species Interactions Ways in which the biotic components affect each other… Predation Competition Parasitism Mutualism Commensalism

Predation One organism kills and eats another organism Prey – the organism that is eaten Predator – the one that does the eating

Predation The predators and prey affect each other’s population ↑ prey → ↑ predator → ↓ prey → ↓ predator

Competition When two or more organisms of the same or different species attempt to use the same limited resource Hyenas competing with lion’s for an animal carcass Ants fighting for territory Birds competing for a mate Flowers competing for pollinators

Competition

Parasitism When one organism benefits from the relationship and the other is harmed Parasite – organisms that live in or on another organisms and feed on it Tick, flea, tapeworm Host – the organism the parasite takes its nourishment from Parasites will not usually kill their host

Parasitism

Mutualism A relationship between two organisms in which both organisms benefit The bacteria in your intestines Insects and flowers

Commensalism A relationship in which one species benefits and the other is neither harmed nor helped