The Biology of Ecosystems

"When we try to pick out anything by itself, we find it hitched to

everything else in the universe." John Muir

What would happen if all the lions on an African savanna were killed or removed? Flora and Fauna?

Ecosystem -- all the different organisms that live in a certain area (the biotic), along with the abiotic factors.

Often times these systems do not have clear boundaries.

Organisms and Species -- An organism is an individual living thing. A species is a group of organisms that are able to produce fertile offspring and share common genes. For Example: Mr. Black-Organism, Homo Sapiens-Species; Fido-Organism, Canine Domesticus-Species.

Population - is a group of individuals of the same species living in a particular place. (Humans living in New Castle)

Community- a group of interacting populations of different species.Examples: pond community, desert community, forest community, etc.

Niche - an organism’s way of life. All of its relationships with its environment.

Environment consists of what?

•All living things (biotic)

•All nonliving things (abiotic)

A Habitat - the actual place that an animal lives. 

What is the difference between a Habitat and a Niche?

What is the job of a lion?

•Control the population of prey

What is the job of a gazelle?

•Food source for predators

•Control the plant growth on the savanna

Does a lion serve a purpose for its prey?

Refining gene traits.

•Faster prey will survive

•Those with better camouflage will avoid becoming prey

•Those who don’t need to move around much more often

Ecological Interactions

How Species Interact With Each other

I. Predation - when one organism kills and eats another organism  Predator does the eating. Prey is eaten.

Natural Selection- only animals that are the fastest, strongest and healthiest are able to live on and reproduce. Thereby increasing desirable gene traits in their offspring

II. Competition - occurs when two or more organisms of the same or different species attempt to use the same limited resources. List examples:

sunlight, scavengers, exotic species, vines (kudzu), Pandas.  Can happen even if they never come into contact: (Pollinators and nocturnal and daytime feeders.)

III. Parasitism - the relationship when organisms live in or on another organism without immediately killing the organism. (Gee-- I wonder Why?)

A Host - the organism that the parasite gets its nourishment from.

Most organisms are negatively affected by parasites. They may be weakened by parasitic relationships hence making them more vulnerable to predators. List Examples:

IV. Mutualism - is a cooperative partnership between two species in which both benefit.

List Examples:

Our intestines have millions of bacterium living inside. They help us digest food and produce Vitamin K that aids in blood clotting.  We provide living arrangements and food .......they help us digest food. 

V. Commensalism - is a relationship in which one species benefits and the other is neither helped nor harmed.

Remoras are fish that attach themselves to sharks and eat the scraps food that float around a shark when it is eating. The Remora benefits and the shark is neither harmed of helped.

Why is it advantageous for a parasite to not kill its host? How could you show a suspected case of mutualism is not commenselism?

Adapting to the Environment

 

Adapting to the environment occurs in three ways

• I. Evolution through Natural Selection

• II. Co-evolution

• III. Extinction

I. Evolution by Natural Selection:

1. All organisms have the ability to produce more offspring than can possibly survive. Ex.: Fish and frogs lay millions of eggs. Most do not survive or there would be millions of fish and frog offspring from one individual.

2. The environment contains things that kill organisms. The environment is often hostile: hot/cold dry/flooded. Predators are common - competition limits resources. Darwin called this a “struggle for existence”

3. Individuals vary in their traits. They may differ in size color, speed, resistance to disease and many other traits. This may be an inherited factor to influence natural selection. 

4. Some inherited traits may give individuals an advantage in coping with environmental challenges. This allows them to survive longer and produce more offspring. They are naturally selected for survival

5. More species with advantageous traits have more offspring; each new generation has more offspring with the advantageous traits than the previous generation. Gradually, over many generations, that species evolves by natural selection…

This is a form of adaptation - an inherited trait that increases an organism’s chance of survival.

II. Co-evolution

When two species evolve in response to each other. Predator/ Prey relationships often spur this type of co-evolution.

Why?

Plants and herbivores - plants cannot move hence they develop toxic responses. Over time the herbivore develops a resistance to the toxicity.

Crabs and snails: The stronger the claws get on a crab, the harder the shell gets on the snail.

Why?

III. Extinction

The species simply ceases to exist.

Evolution is the change over time and adaptation is the trait that is changed