Transcript Charles Darwin. - Teaching Biology Project

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Charles Darwin’s
Theory of Evolution
Charles Darwin explored the world on the Beagle
for 5 years collecting specimens for the
Museum of Natural History in London.
Charles Darwin
Galapagos Islands: a wide range of finch
species descended from a single species.
Different species adapted to different feeding
niches (seeds, fruits, insects).
Life Nature
Library 1971
Charles Darwin
• Published his theory of evolution
based on natural selection in 1859.
Natural selection
The increased reproduction of individuals
that have traits (features / characters) better
suited to survive and reproduce in an
environment.
Traits
Characters or features that are genetically
inherited.
They may be obvious, e.g. eye colour and
height.
They may be less obvious, e.g. aggression,
speed, memory.
• Evolution is the change in genetic
make-up (traits) of populations
through time (e.g. modern humans
becoming taller).
• Population: members of a species
that occupy a specific region and which
come together to mate.
Biological species concept
A group of interbreeding organisms that can
produce fertile offspring.
e.g. Homo sapiens – modern humans
We can mate with anybody from anywhere in the
world, and our children can have children. This
makes us all ONE species.
Darwin observed:
That all over the
world, geological
sequences
contained simpler,
more primitive
forms lower down.
Genes are not the only factor that
determine an organism’s appearance.
• Environmental influences: A person
with a dominant gene for height could
end up short due to poor diet and living
conditions.
• Mutation: random change in an
individual’s genes.
E.g. of a useful mutation:
A lamb born with short, bent legs that
prevented it from jumping fences.
Used in breeding to establish short-legged sheep.
Traits that may ensure the survival of the
fittest animal in a specific environment
could include for example:
An eagle that has inherited
1. very good eye sight for hunting
2. an ability to fly well
3. a means of attracting a lot of mates
for reproducing with, e.g. a song.