1. Evolution
Submitted by:
Nikko Dave Francisco III-1

2. Introduction to Evolution
Humans have undergone major anatomical
changes over the course of evolution. This
illustration depicts Australopithecus afarensis
(center), the earliest of the three species; Homo
erectus (left), an intermediate species; and
Homo sapiens (right), a modern human. H.
erectus and modern humans are much taller
than A. afarensis and have flatter faces and
much larger brains. Modern humans have a
larger brain than H. erectus and an almost flat
face beneath the front of the braincase.

3. Before Darwin
Georges Cuever (1769-1832)
French vertebrate zoologist, comparative
anatomist and paleontologist
names as the "Father of Comparative Anatomy
and Paleontology“
proposed fixity of species and catastrophism

4. Fixity of Species
- no changes occured in the structure of species
due to adaptation
- unable to adapt will result to extinction of the
species
Catasrophism
- belief that periods of catastrophic extinction
occured
- after the mass extinction, repopulation of
surviving species took place, giving the
appearance of change through time

5. Jean Baptiste de Lamarck (1744-1829)
French invertebrate zoologist and botanist
proposed the theory of inheritance of acquired
characteristics

6. Theory of Inheritance of Acquired Characteristics
- belief that characteristics acquired during the lifetime
of an organism can be passed on to the offspring
- classic example he used to explain this theory was the
long neck of giraffe
- he believed that the long neck of giraffe developed
over time because previous generations that stretched
their necks to reach food high in trees passed on their
long necks to their offspring
- this theory was rejected because phenotypic changes
acquired during an organism's lifetime do not results in
genetic changes that can be passed on the next
generations

7. Darwinism
the explanation of evolution proposed by
Charles Darwin in his book The Origin of
Species by means of Natural Selection (1859)

8. Charles Darwin(1809-1882)
British naturalist
born on February 12, 1809 at Shrewsbury, England
finished a BA degree in 1831
joined a 5-year voyage of the HMS Beagle (1831) as naturalist
to study the geology and biology of the journey
published several books such as Zoology of the Beagle (1840),
The Structure and Distribution of Coral Reefs (1842),
Geological Observations on Volcanic Islands (1844), The
Origin of Species by means of Natural Selection (1859), The
Descent of Man (1871)
proposed and formulated the process of evolution in his book
The Origin of Species by means of Natural Selection

9. Concepts of Evolution
The characteristics of living things change with
time. Change in the characteristics of
population over the course of many
generations.
The change is directed by natural selection
process. Changes are in the genetic makeup of
the population.

10. Evidences of Evolution
fossil - a record of the history of life that shows that organisms have
changed over time
biogeography - the study of the distribution of life forms shows that
organisms evolve in one locale and then spread to other regions
comparative anatomy - related organisms share a unity of plan
e.g. all vertebrate forelimbs contain the same sets of bones despite
a similar functions
comparative embryology - related organisms developed similarly, all
vertebrates at some time have paired pharyngeal pouches
bordering gill clefts, yet only fishes and amphibian larvae have gill
comparative biochemistry - almost all living things use the same basic
biochemical molecules, including DNA, ATP, and many identical or
nearly identical enzymes

11. Organic Evolution
defined as change in genetics of a population over time
(generations)
a population refers to all individuals of the same species
living in a defined area at the same time
can be studied at two different levels:
microevolution, which refers to small-scale genetic
changes within populations
macroevolution, which refers to the large-scale results
of genetic changes in population, including the
formation of new species and the evolution of large
scale trends seen across species in what traits they
have

12. Microevolution
- occurs through several mechanisms
- the first of these that was discovered, and the form which is best known, is natural selection by Charles Darwin and Alfred Russel Wallace
- natural selection is evolution that occurs because individuals with some traits survive and reproduce better than do individuals with other traits
- as a result, those traits that result in high survival and reproduction are passed from generation to generation, through reproduction, at a higher
rate than other traits - these traits become increasingly more and more common in populations
- fitness refers to the degree to which individuals with certain traits are expected to survive and reproduce
- natural selection can also be said to occur because of difference in fitness within a population
- adaptation refers either to the process of natural selection, or to a trait that has evolved through natural selection
- there are four properties of a population called as "Darwin's Four Postulates" that, together, result in natural selection; these are:
1. more young are produced each generation that can survive to reproduce; this is generally observed in species; many of the offspring
born to any generation die before reproduction
2. individuals in a population vary in their characteristics; this is also generally observed in species; individuals are not identical to one
another
3. the differences among individuals are based on genetic differences; the genetic basis for many traits in natural populations and often
have observed that the differences among individuals are present because of genetic differences
4. individuals with some characteristics survive and reproduce better (have higher fitness) than do individuals with other characteristics;
this has now been observed in hundreds of populations
- if these four postulates are all true of a population, they result in natural selection
- those individuals with higher fitness end up being the ones who survive each generation, and as a result reproduce more
- since the traits are genetic, they get passed on to the next generation, and therefore become more common than they were in the previous
generation

13. Macroevolution
- evolution within populations (microevolution) can occur through
several other mechanisms
- speciation refers to the formation of new species; it occurs when
one ancestral species evolves into more than one (typically two)
descendant species
- species are typically defined as groups of organisms that are so
similar to each other that they can reproduce and produce healthy
fertile offspring
- the idea is that if organisms belong to the same species then they
can reproduce and their offspring can also survive and reproduce
- if organisms belong to different species, they can't reproduce with
each other or, if they do, their offspring die or are sterile
- since speciation occurs when one species evolves into more than
one new species, it increases the number of species that exist

14. Natural Selection
the mechanism for evolution
proposed by Charles Darwin and Alfred Wallace
in 1858
caused by environmental selection of organism
most fit to reproduce, resulting in adaptation

15. Preconditions of Natural Selection
The members of the population must have
heritable variations.
After each generation, in the population, more
individuals are produced than can survive and
reproduce.
Some individual possessed adaptive
characteristics giving them greater chances of
survival than any other individuals.

16. Results of Natural Selection
Advance body organization and improve species.
Preserve and accumulate small-inherited
modifications that are profitable for the
species.
The favored form increases in number and
generally the less favored decreases and
become rare.

17. Summary
Evolution is a slow process of change by which
organisms have acquired their distinguishing
characteristics.
It has been going on since the Earth was formed
billions of years ago.
The theories of evolution are Lamarck's Theory of
Acquired Inheritance and Darwin's Theory of
Natural Selection.
Natural Selection as proposed by Darwin was the
mechanism for evolution.