Organization of life Ch 4

ecosystem – interactions of the abiotic and biotic components of a particular place

Ecosystems Ecosystems need 5 basic items to survive. Energy source Minerals Water Oxygen Living organisms

biotic – refers to organisms, or their remains, in the environment Examples: organisms, dead parts of once living organisms, waste products

abiotic – refers to nonliving things in the environment Examples: air, water, rocks, sand,light

species (both singlular & plural) – unique group of genetically similar organisms which are reproductively isolated, and which can mate and produce viable (living) and fertile offspring  

population - all of the individuals of the same species that live in a particular place at a specific time  

Community A group of various species that live in the same place and interact with each other. Example: A pond environment with different fish, frogs, bugs around pond, and plants in and out of pond.

habitat – place where a particular organism lives in the environment

Evolution evolution = change over time, and considered the process by which modern organisms descended from ancient organisms

On his five-year voyage around the world, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way that life changed over time.

On his trip, Darwin was puzzled not only by where the different organisms lived, but that they seemed remarkably suited to live in what ever environment they inhabited. He also wondered why very similar environments had very different organisms.

Fossils presented another problem Fossils presented another problem. Some looked very similar to organisms alive then, while others were completely different. Why had so many disappeared? How were they related to the organisms presently living?

The volcanic Galapagos Islands were formed about 3 The volcanic Galapagos Islands were formed about 3.3 million years ago, so the organisms found there could have only reached the Islands by flying, swimming, or drifting on floating mats of vegetation.  

There are only 2 species of mammals, 7 kinds of reptiles, and 20 species of birds, most of which are finches, on the Islands.  

Although the body shape of the finches is similar, their beaks are quite different in size and shape—an adaptation to a particular food source—seeds, insects, or fruits.

These different finches probably had a common ancestor which arrived from the western coast of South America about 100,000 years ago.

Since they had little or no competition for food or habitat, the population rapidly expanded and filled various ecological niches.  

niche - the total of an organism’s utilization of the abiotic and biotic resources in its environment—the function/position an organism has in its environment  

Natural selection eliminated the finches least able to utilize the available resources present on the Islands.

Natural selection is an editing process, whereby inherited characteristics provide a wide range of phenotypes, while environmental factors eliminate those that are not well-suited to the environment.  

Natural selection operates on populations, not individuals Natural selection operates on populations, not individuals. It affects the phenotypes which survive and reproduce and which do not.

Darwin’s 5 points Population has variations. Some variations are favorable. More offspring are produced than survive. Those that survive have favorable traits. A population will change over time.

Darwin proposed his theory of natural selection after observing various breeds of pigeons resulting from artificial, or selective breeding.

artificial selection –selective breeding of organisms by humans for specific characteristics (dogs, cats, food we eat) Those genotypes not eliminated by humans/Nature pass their genes on to the next generation.

Resistance Evolution   Resistance is the ability of one or more organisms to tolerate a particular chemical designed to kill it. Give an example of something you know has resistance.

Resistant Bacteria