Biology

1. Cluster of events at the more resent end of the timeline.Few, widespread events at the deep time end of the timeline.

1. Geological events preceded biological events.

1. Plant events preceded animal events.

Evolution – Change in the characteristics of a population over many generations. It can NOT happen in one generation (that would be a mutation).

Mutation – Sudden alteration in the genetic make–up (chromosome structure or number) of one individual.

Variation – Difference between individuals.

Some of Darwin’s sketches of Finches while aboard the beagle Note the variation in

beak size and shape How do you think

these variations helped the finch?

Some of the Finch specimens Darwin collected. What other

variations do you see?

Adaptation – Inheritable and beneficial traits that better equip an individual to survive in a particular environment.

Fitness – Ability of an organism to reproduce and pass it’s genes on to the next generation. An animal with a higher fitness will reproduce more than other animals in the same environment.

A polar bear is well adapted to life in the arctic.

What are some adaptations?

A polar bear is well adapted to life in the arctic.

What are some adaptations? Thick fur and blubber

to stay warm White fur helps them

to camouflage Large feet acts like

snow shows for walking on ice

Charles Darwin – Spent five years aboard the HMS Beagle observing a variety of species in a wide variety of habitats.

Darwin observed that each type of organism was well suited for the environment in which it lived, yet seemed to be related to other organisms in other parts of the world.

Published On the Origin of Species in 1859 to explain his theory of descent with modification.

Alfred Wallace – Published his paper first, but is not often recognized. Darwin’s theory was

more detailed. Darwin’s paper

contained more extensive evidence.

Darwin proposed a mechanism for change over time.

Natural selection – Mechanism used to explain the theory of evolution.

Natural environmental pressures select the best adapted individuals in a population to survive longer and reproduce more. Thus, passing on their beneficial traits to the next generation.

Examples of environmental pressures for a plant include temperature, sunlight, water, minerals in the soil

If the environment changes, other traits may be selected for.

1) The members of a population have heritable variations.• size, coloration, strength, behavior

2) In each population, many more individuals are produced each generation than the environment can support.

3) Some individuals possess adaptations that enable them to survive and reproduce more than other individuals.

4) An increasing number of individuals in succeeding generations possess the adaptation.

5) The result of natural selection is a population adapted to its local environment.

1) Variation within a population

2) Struggle for existence3) Survival of the fittest4) Descent with modification5) Change over time