Biodiversity - WordPress.combiodiversity.notebook April 30, 2012 Biodiversity •the variety of forms of life on Earth •the study of the processes that create and maintain diversity,

biodiversity.notebook April 30, 2012

Biodiversity


Biodiversity• the variety of forms of life on Earth• the study of the processes that create and maintain diversity, and variation within populations

Recall that the more diverse an ecosystem is, the more stable it is.

Likewise... the more variation that occurs in species, the greater its chance of survival!


The individuals in the population of a highly adapted species will all have similar traits, and if conditions change, they may be threatened with extinction.

If a species exhibits a large number of natural variations in its characteristics, the odds of some individuals having the traits that will help them survive changing conditions increases.

Hmmmm...Populations are stable when living conditions are stable, but what happens if living conditions change?


So, sexual

reproduction is

GOOD!

Variety in genetic traits

increases survival

of a population!!!

This means trouble for all living things,

including us!!!

Decreased biodiversity threatens the stability of the biosphere!!!

Extinction

threatens

the levels

of biodiver

sity on

Earth!!!!

1 2

3

45


SexualReproduction

Remember Sexual reproduction is necessary to create genetic diversity

(variation) in a species.

Asexual reproduction creates offspring that are identical to their parent no diversity.

Sexual reproduction creates unique offspring because of the random combination of genetic traits from

both parents.

Meiosis???


Natural Selection Well, I'll be a monkey's uncle!

Charles Darwin

Charles Darwin proposed the theory of Natural Selection; a scientific explanation for the diversity we see on Earth.

Natural Selection: Survival of the FittestOrganisms that are best suited to the environment they live in are the most fit, and so have the best chance of reproducing and passing on their traits to offspring.

Over time, (many generations), the traits individuals in a population have begin to vary considerably from the initial parents. Sometime variations are so extreme that a new species is created!


This process of slowly changing the traits of a species over time is called....

EVOLUTION!


If individuals in a species are unable to adapt to the changes in their environment, the species will eventually become extinct.

Sometimes variations in a species, such as colour, can become the saving trait in a changing environment.


What will this hungry bird find to eat?


Which colour variant is most fit to the "grey" environment?

Which colour variant will be more successful at reproduction?

How do you think the population will look after several generations?


A case just like this was documented in the species Biston betularia, the peppered moth, in England.

There were two colour variants of the species: light (common) and dark (rare).

The light variant once camouflaged

well against tree bark.

After the Industrial Revolution, the tree trunks were darkened by soot. The dark variant, once easily preyed upon, now camouflaged better against tree trunks.

This is a classic example of the importance of genetic variability in adapting to changing or new environments.

Over time, the dark variant became more common, but the species survived because it was able to adapt.

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Biodiversity - WordPress.combiodiversity.notebook April 30, 2012 Biodiversity •the variety of forms of life on Earth •the study of the processes that create and maintain diversity,