This document discusses Darwin's theory of evolution by natural selection. It explains that Darwin observed greater diversity of species during his travels than in his native country, which led him to propose that all species gradually change over time and descend with modification from other species. Modern understandings incorporate genetics, showing how mutations in DNA can provide variation for natural selection to act upon. Fossil evidence also documents how life has changed over time.

1. Presented by Noor ul huda
Department MLT

2. Evoulution and theory.
Darwan’s observations.
Modern understandings.
Natural selection of evoulution
Evidences
Geographical distributions.
Summary

5. Change over time
It’s a gradual change in a species over time

6. A well supported testable
explanation of phenomena that
have occurred in the natural world

8. Darwin saw far more diversity during his
travels than he saw in his native country

9.  The physical and behavioral changes that make
natural selection possible happen at the level of
DNA and genes. Such changes are called
mutations. "Mutations are basically the raw
material on which evolution acts," Pobiner said.
 Mutations can be caused by random errors in DNA
replication or repair, or by chemical or radiation
damage. Most times, mutations are either harmful
or neutral, but in rare instances, a mutation might
prove beneficial to the organism. If so, it will
become more prevalent in the next generation and
spread throughout the population.

10.  Darwin didn't know anything about genetics,
Pobiner said. "He observed the pattern of
evolution, but he didn’t really know about the
mechanism." That came later, with the
discovery of how genes encode different
biological or behavioral traits, and how genes
are passed down from parents to offspring.
The incorporation of genetics and Darwin's
theory is known as "modern evolutionary
synthesis."

11. Darwin proposed that each living
species has descended, with
changes from other species over
time
He called this Descent with
Modification

12. Darwin was convinced that a
process like artificial selection
occurs in nature
High birth rates and a shortage for
resources would force organisms
into a competition for resources

13. By comparing fossils from older
rock layers with fossils from
younger layers, scientists could
document the fact that life on
Earth has changed over time

15. Many species share similar
characteristics because
they inhabit similar
environments

17. 1. Individual organisms in nature differ from one
another. Some of this variation is inherited
2. Organisms in nature produce more offspring
than can survive, and many of those that
survive do not reproduce.
3. Because more organisms are produced than
can survive, members of each species must
compete for resources.
4. Because each organism is unique, each has
different advantages and disadvantages in the
struggle for existence.

18. 5. Individuals best suited to their environment survive and
reproduce most successfully. The characteristics that
make them best suited to their environment are passed
on to offspring. Individuals whose characteristics are not
as well suited to their environment die or leave fewer
offspring.
6. Species change over time. Over long periods, natural
selection causes changes in the characteristics of a
species, such as in size and form. New species arise,
and other species disappear.
7. Species alive today have descended with modification
from species that lived in the past.
8. All organisms on Earth are united into a single tree of life
by common descent.