Transcript Adaptation, Natural Selection and Evolution

Adaptation, Natural
Selection and Evolution
Natural Selection
•
Response: Natural selection has
no intentions or senses; it
cannot sense what a species
“needs.” If a population happens
to have the genetic variation
that allows some individuals to
survive a particular challenge
better than others, then those
individuals will have more
offspring in the next generation,
and the population will evolve. If
that genetic variation is not in
the population, the population
may still survive (but not evolve
much) or it may die out. But it
will not be granted what it
“needs” by natural selection.
Survival of offspring that have favorable traits
Developing Theories of Evolution
• Jean Baptiste de
Lamarck was one of the
first to develop a
theory of evolution
• Lamarck hypothesized
that giraffes had short
necks and as grasses
died their necks had to
stretch to eat tree
leaves, passing on that
trait to offspring
• Lamarck did not have
enough evidence and was
eventually proven wrong
Charles Darwin - 1831
• Sailed on the HMS
Beagle on a 5 year
expedition of S.
Pacific and S.
America where he
discovered 13
different species of
Finches and
different species of
tortoises on every
island.
• Why did Darwin think
the finches may have
had a common ancestor?
• Why were the beaks
shaped differently?
Natural Selection is a term used to describe the theory
of evolution. Nature favors the organism best suited
for their environment.
The theory includes the following ideas.
• Overproduction – species produce more than can survive and not
all survive because of lack of food and living space
• Struggle for Existence – Offspring compete and only a few will
live long enough to reproduce
• Variation- The offspring of each generation differ, they are not
exactly the same. Some are stronger or faster. Individuals in a
species differ/vary
• Survival of the Fittest- some variation make organism better
suited to survive and pass on their genetic traits/reproduce
• Evolution of a species – The passing on of favorable traits, make
the unfavorable traits disappear creating over time a new
species
Environment affects Natural Selection
• Insufficient resources, like living space, food and
water – when organism compete the stronger, faster
will survive to pass on their traits
• Human Activities such as hunting and construction can
use up the resources or cause extinction
• Pollution caused the black peppered moths to blend
into the soot covered trees in England, so the gray
ones were eaten, now England cleaned up its soot and
the gray moth population has risen
• Extinction occurs when organisms can not adapt to
their environment and they die out with out
reproducing and passing on their traits. Over hunting
and fishing by humans can cause this also.
Humans have changed over time
• Anthropology the study of the development
of man and society.
• Human like fossils have been discovered
dating back 3.5 million years old.
• Fossil evidence shows related species date
back 6 million years.
• All modern humans are Homo sapiens
• Earlier man are called Neanderthals ( sloping
foreheads and heavy brow ridges, 130,000 –
35,000 years ago) and Cro- Magnons ( look
like modern man, 35,000 – 10,000 years ago)
Man Changes
Neanderthal