Download Adaptations Over Time - St. Thomas the Apostle School

Adaptations
Over Time
Chapter 6
Ideas about Evolution
Evolution-changes in inherited characteristics of a
species over time.
-A species is a group of organisms that share similar
characteristics and can reproduce among themselves.
Jean Babtiste Lamarck
• Developed a hypothesis to explain how species change over time.
• He traveled through the Galapagos Islands collecting data on species
of animals and their acquired traits.
Charles Darwin- model of Evolution
• In December 1831 Charles Darwin, a young naturalist, sailed from
England on a journey to South America on the HMS Beagle. He
recorded observations on plants and animals.
• He was amazed by what he found on the Galapagos Islands.
• He observed the beaks of finches are related to its eating habits.
• He also noticed the finches were similar to a finch species he had
seen on the South American Coast.
• He found they had to compete for food, and those with beak shapes
that allowed them to eat available food survived.
Darwin’s model of Evolution
• He hypothesized that plants and animals on islands off the coast of
South America originally came from central and South America.
• He observed that the species of finches on the islands looked similar
to a mainland finch species.
• He reasoned that members of a population best able to survive and
reproduce will pass their traits to the next generation; over time.
Differences can result in separate species.
• He published - THE ORIGIN OF SPECIES in 1859
Darwin’s hypothesis became known as the the theory
of evolution by NATURAL SELECTION-organisms with
traits best suited to their environment will more likely
survive and reproduce
How do Lamarck’s theory and Darwin’s theory
differ?
VARIATION- an inherited trait that makes an
individual different from other members of its
species
• Adaptation- a variation that makes an organism better suited to its
environment.
• Many environmental factors can cause change in the source of genes.
Geographic Isolation- can make two populations
so different they become different species.
Two models explain the speed of
evolution
1. Gradualism- describes evolution as a slow, ongoing process
2. The Punctuated Equilibrium model says gene mutation can result in
a new species in a relatively short time.
CLUES ABOUT EVOLUTION
Fossils found in Sedimentary rock show evidence that living things
evolved.
Fossil age can be determined by two basic methods.
1.Relative dating- looks at the fossil location in a particular layer
or rock; older rock layers are under newer rock layers.
• 2. Radiometric Dating- compares the amount of radioactive element
with the amount of nonradioactive element in a rock
Fossil records have gaps.
• Incomplete rock record; most organisms do not become
fossils
• Enough fossils have been discovered for scientists to
conclude that complex organisms appeared after simpler
ones.
• Most organisms that have ever existed are now extinct
Direct evidence- such as the development of antibiotic resistance in
bacteria; support evolution.
Indirect evidence supporting evolution:
1. Embryology- the study of embryos and their development, shows
similarities amongst all vertebrate species
2. Homologous body parts- body parts that indicate two or
more species share common ancestors
3. Vestigial structures- structures that don’t seem to have a
function but might have once functioned in an ancestor.
DNA can provide evidence about how closely
related organisms are.
THE EVOLUTION OF
PRIMATES
PRIMATES- groups of mammals with:
• 1. Opposable thumbs
• 2. binocular vision
• 3. flexible shoulders
Hominids- appeared 4 to 6 million years ago
and had larger brains then apes.
• Fossils such as Australopithecus, point to Africa as the origin of
Hominids.
• Homo-habilis and Homo erectus are thought to be early human
ancestors
Lucy
Lucy- australopithicus
Homo- Sapiens- Began evolving 400,000 years
ago
Neanderthals – had short heavy bodies with thick bones, small
chins, and heavy brow ridges.
• Disappered about 30,000 years ago
• Not thought to be direct ancestors of modern humans
Cro –Magnon fossils date from around 10,000 to 40,000 years ago;
are thought to be direct ancestors of early Homo Sapiens.