CHAPTER TEN
EVOLUTION BY NATURAL
SELECTION
HYPOTHESIS AND THEORY
● Observations made and facts analyzed during discovery inquiry which lead
to generalizations via inductive reasoning
● Explanatory inquiry allows scientists to try to find explanations for
those generalizations. These are the hypotheses.
● Deductive reasoning is used during hypothesis testing
● Laws are large generalizations. The fact-based explanation for these
laws is referred to as the theory.
EVOLUTION
● The theory of evolution states that all things, living and nonliving, of
today arose from things in the past
● Biological evolution refers to the changes of living things from a
common ancestor.
● ‘Descent with modification’
DIVERSITY OF LIFE AND EVOLUTION
BIODIVERSITY: a wide range of species and organisms making up those species
GEOLOGICAL TIME SCALE: an established scale that deals with the long periods
of time of the earth
EXTINCTION: a natural occurrence in which a total species dies off. Usually
matches the rate of occurrence of a new species.
● Major animal groups appeared during the Cambrian Period
● Mass extinctions are when more than 50% of species vanish over a few
million years
, VARIATION
SPECIES: Similar organisms which interbreed to produce fertile offspring
POPULATION: A group of species in the same location
VARIATION: Differences within a population
SOURCES OF VARIATION
1. MUTATIONS
2. CROSSING-OVER (MEIOSIS)
3. RANDOM ARRANGEMENT (MEIOSIS)
4. RANDOM FERTILIZATION
CONTINUOUS VARIATION
● Has a range of phenotypes for one particular characteristic
● Many genes are working together
● Polygenic inheritance
● Often affected by environmental influences
● Eg milk yield
DISCONTINUOUS VARIATION
● Does not have a range of phenotypes for one particular characteristic
● Can’t be measured across a complete range
● The characteristic is either there or it is not
● Controlled by alleles of a single gene
● Environment has no effect
EVIDENCE FOR EVOLUTION
● Based off of major assumption
● The assumption is that species change through the forces of natural
selection and the evidence is that different species are related
EVOLUTION BY NATURAL
SELECTION
HYPOTHESIS AND THEORY
● Observations made and facts analyzed during discovery inquiry which lead
to generalizations via inductive reasoning
● Explanatory inquiry allows scientists to try to find explanations for
those generalizations. These are the hypotheses.
● Deductive reasoning is used during hypothesis testing
● Laws are large generalizations. The fact-based explanation for these
laws is referred to as the theory.
EVOLUTION
● The theory of evolution states that all things, living and nonliving, of
today arose from things in the past
● Biological evolution refers to the changes of living things from a
common ancestor.
● ‘Descent with modification’
DIVERSITY OF LIFE AND EVOLUTION
BIODIVERSITY: a wide range of species and organisms making up those species
GEOLOGICAL TIME SCALE: an established scale that deals with the long periods
of time of the earth
EXTINCTION: a natural occurrence in which a total species dies off. Usually
matches the rate of occurrence of a new species.
● Major animal groups appeared during the Cambrian Period
● Mass extinctions are when more than 50% of species vanish over a few
million years
, VARIATION
SPECIES: Similar organisms which interbreed to produce fertile offspring
POPULATION: A group of species in the same location
VARIATION: Differences within a population
SOURCES OF VARIATION
1. MUTATIONS
2. CROSSING-OVER (MEIOSIS)
3. RANDOM ARRANGEMENT (MEIOSIS)
4. RANDOM FERTILIZATION
CONTINUOUS VARIATION
● Has a range of phenotypes for one particular characteristic
● Many genes are working together
● Polygenic inheritance
● Often affected by environmental influences
● Eg milk yield
DISCONTINUOUS VARIATION
● Does not have a range of phenotypes for one particular characteristic
● Can’t be measured across a complete range
● The characteristic is either there or it is not
● Controlled by alleles of a single gene
● Environment has no effect
EVIDENCE FOR EVOLUTION
● Based off of major assumption
● The assumption is that species change through the forces of natural
selection and the evidence is that different species are related
