EVOLUTION
Biological evolution the change in the gene pool of a population during the course of time
by processes such as mutation, natural selection and genetic drift – it is modification by
descent
It is a scientific theory, not just a hypothesis – it has a reliable body of evidence that it has
developed through extensive and repeated observations and experiments to support it
Different lines of evidence that have confirmed the scientific theory of evolution
1. Fossil records/modification by descent
2. Biogeography
3. Genetics
4. Homologies & embryology
o FOSSIL RECORDS/MODIFICATION BY DESCENT
3.5 billion rock record – long enough for evolution to have taken place
Radiometric dating – dates rocks
Increase in complexity over time
Increase in diversity over time
Descent w/ modification, changes occur to the same species over time
Existence of intermediate forms between groups (transitional fossils) – suggests that
one species may have given rise to another. E.g. mammal-like reptiles – between
mammals and reptiles
o EVIDENCE FROM BIOGEOPGRAPHY
DEF: the study of where species occur, and why
Different regions with similar climatic conditions contained very different animals &
plants. Species could evolve without exchanging DNA/competition from similar
species
Species on islands differed slightly but were more closely related to species on the
nearest mainland, despite the different environments – ocean acted as a barrier
which allowed organisms to adapt differently to the environment on each island,
and for them to evolve into a new species
o EVIDENCE FROM GENETICS
Studying chromosomal DNA and mitochondrial DNA
All organisms descended from a common ancestor because they all have DNA &
RNA, there are genes in all organisms that are encoded to make identical proteins
The more DNA sequences shared, closer the relationship, more recently they
diverged from a common ancestor
o HOMOLOGY AND EMRBYOLOGY
DEF: organisms w/ similar structures might have acquired these structures from a
common ancestor & therefore are on the same evolutionary lineage, features are
known as homologies
Similar in structure, position, development – but they do not necessarily perform the
same function
Embryology studying embryos of various organisms and similarities between
species over time
1700 - 1800
Biological evolution the change in the gene pool of a population during the course of time
by processes such as mutation, natural selection and genetic drift – it is modification by
descent
It is a scientific theory, not just a hypothesis – it has a reliable body of evidence that it has
developed through extensive and repeated observations and experiments to support it
Different lines of evidence that have confirmed the scientific theory of evolution
1. Fossil records/modification by descent
2. Biogeography
3. Genetics
4. Homologies & embryology
o FOSSIL RECORDS/MODIFICATION BY DESCENT
3.5 billion rock record – long enough for evolution to have taken place
Radiometric dating – dates rocks
Increase in complexity over time
Increase in diversity over time
Descent w/ modification, changes occur to the same species over time
Existence of intermediate forms between groups (transitional fossils) – suggests that
one species may have given rise to another. E.g. mammal-like reptiles – between
mammals and reptiles
o EVIDENCE FROM BIOGEOPGRAPHY
DEF: the study of where species occur, and why
Different regions with similar climatic conditions contained very different animals &
plants. Species could evolve without exchanging DNA/competition from similar
species
Species on islands differed slightly but were more closely related to species on the
nearest mainland, despite the different environments – ocean acted as a barrier
which allowed organisms to adapt differently to the environment on each island,
and for them to evolve into a new species
o EVIDENCE FROM GENETICS
Studying chromosomal DNA and mitochondrial DNA
All organisms descended from a common ancestor because they all have DNA &
RNA, there are genes in all organisms that are encoded to make identical proteins
The more DNA sequences shared, closer the relationship, more recently they
diverged from a common ancestor
o HOMOLOGY AND EMRBYOLOGY
DEF: organisms w/ similar structures might have acquired these structures from a
common ancestor & therefore are on the same evolutionary lineage, features are
known as homologies
Similar in structure, position, development – but they do not necessarily perform the
same function
Embryology studying embryos of various organisms and similarities between
species over time
1700 - 1800
