1. Evolution and Natural Selection
Unit 7a
Evolution and Natural Selection

2. Charles Darwin Traveled on board the HMS Beagle 1831-1836
Using observation and insight, proposed the theory of evolution by natural selection (gradualism)
Organisms will change genetically over time
Suggests that present day organisms descended from a common ancestor

3. Evolution Definition:
The process of cumulative change in the heritable characteristics of a population
Changes must be passed on genetically from one generation to the next
Can result in a new species
Cannot interbreed with ‘old’ species
Heritable – the changes mused be passed on from one generation to the next, does not happen overnight
Cumulative – one change is usually not enough to have a major impact on the species
Population – changes do not effect just one individual

4. Speciation Rates How fast/when evolution occurs
Punctuated Equilibrium:
Step-like pattern of gradual changes that occur

5. Evidence of Evolution Fossil Record Artificial Selection
The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock
Evidence of the appearance, change, and disappearance of species
Artificial Selection
Selective breeding allows breeders to create unique combinations of characteristics
Homologous anatomical structures
Similar in form and function
Found in seemingly dissimilar species

6. Mechanism for Evolution
Natural Selection
Example: antibiotic resistance in bacteria
Due to too many offspring/not enough resources
Results in competition for key resources
Those organisms with favorable traits survive and reproduce
These traits get passed on to the next generation
“Survival of the fittest”
Concept of natural selection is not always true
Example: Extinction of the dinosaurs

7. Causes of Variety Choice of mate Mutations in DNA Sexual reproduction
Can lead to disease
Can produce an advantageous characteristic
Example - Slightly faster growing tree
Sexual reproduction
Powerful source of variation in a population
Thousands of genes are mixed and combined
Meiosis / Fertilization

8. Allele frequency and gene pools
Definition: all of the genetic information present in the reproducing members of a population at a given time
Allele frequency
Definition: a measure of the proportion of a specific variation of a gene in a population
Example:
25% of all chromosomes in a population have a certain allele
¼ of the loci for that gene are occupied by that allele

9. Evolution and Alleles
After many generations, allele frequency changes due to:
Immigration
Emigration
Mate choice (reproduction)
Advantageous alleles are more frequent
Disadvantageous alleles are not passed on
No change in allele frequency = no evolution
Big change in allele frequency = evolution has occurred

10. Barriers between Gene Pools
Geographical isolation
Physical barriers prevent males and females from finding each other
Temporal isolation
Incompatible time frames
Behavioural isolation
Lifestyle and habits of on population is not compatible with another
Hybrids
Most are infertile

11. Unit 7b
Classification

12. Classification Putting living organisms into groups Purpose
Trying to make sense of the biosphere
Showing evolutionary links
Predicting characteristics shared by members of a group

13. Modern Classification
Compares
External/internal structures
Geographical distribution
Genetic make-up
Feeding habits
Habitat
Daily activity
Risk
Anatomy

14. All organisms results from a common ancestor
Domains
There are 3 domains
Bacteria / Archaea / Eukarya
All organisms results from a common ancestor

15. Five Kingdoms Animalia Plantae Fungi Protista Eubacteria
76% of all species
Plantae
15% of all species
Fungi
5.6% of all species
Protista
2.8% of all species
Eubacteria
0.3% of all species
Archeabacteria
0.03% of all species

17. Binomial Nomenclature
Consolidated and popularized by Carl Linnaeus (1735)
System of names organisms using two names
‘Bi’ means two / ‘nomial’ means name
‘nomenclature’ refers to a system used to name things
First name
Capitalized
Refers to the genus
Second name
Begins wish a small letter
Refers to the species
Written in italics when typed
Underlined when written by hand
Most are of Greek or Latin origin

18. Taxonomy
Branch of Biology that groups and names organisms based on studies of their different characteristics (living and extinct)
Example: Bangle Tigers and Saber-tooth tigers
Taxon(singular)/Taxa (plural)
Seven taxa
Domain / kingdom / phylum / class / order / family / genus / species

19. Taxonomic Rankings Taxa range from wide-ranging to narrow
There are more organisms found in KINGDOM than in PHYLUM
Wide-ranging taxa include:
general characteristics
more species
Ex. The phylum chordata contains any creature that has a backbone
Narrow taxa include:
Specific characteristics
Fewer species
Ex. The species, Cardinalis cardinalis, will only contain Cardinals

20. Dichotomous Keys Method of classification
Used to reveal the identity of an organism based on certain characteristics