Health Sciences 1001A/B Study Guide - Final Guide: Parapatric Speciation, Allele Frequency, Sympatric Speciation

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Published on 19 Apr 2013
School
Western University
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Health Sciences
Course
Health Sciences 1001A/B
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Bio Midterm 2 Review
Dr. Waugh Content
Lec. 1
The Theory of Evolution Key Concepts
- What is a theory?
- Historical development of evolutionary thought
- Darwinian evolution
- Road map for the evolution course
What is a theory?
common vernacular: an untested idea or opinion; speculation
scientific definition: explanation of a set of natural phenomena, based upon proven or testable hypotheses
and observations
Examples of scientific theories: Natural Selection, Cell Theory, Big Bang Theory
Early evolutionary thought
static classification and characterization
- Aristotle (384-322 BCE) & the Scala natura: The ladder of natural things (how close an organism is to
perfection / gods)
- Natural Theology (1700s)
- Carl von Linne & the Linnean system (1707-78): Involved in the classification of species (based on the
reproductive structure) - Developed the taxonomic Hierarchy
Taxonomic hierarchy = Family Orders Classes Phyla Kingdoms - Domains, all life is divided into
three domains
- le Comte de Buffon (1707-1788) but…vestigial traits are traits that seem to be useless (lost
throughout evolution) Appendix
Transformational theory of evolution
Jean-Baptiste Lamarck (1744 1829)
- Species evolve better fir their environment
- Refer to diagram in notes
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Geological patterns
Georges Cuvier (1769 1832)
- Believed in fixity of species
- Changes in fossil forms a result of repeated catastrophic events and new creations
(catastrophism)
Charles Lyell (1797 1875)
- Natural agents currently at work have been at throughout earth’s history (uniformitarianism)
- (earth has been gradually changing throughout time)
Darwinian Evolution
Charles Darwin (1809 1882)
- Evolution by natural selection: species gradually change over time due to interactions between
individuals’ traits and their environment
Lec. 2
Natural Selection Key Concepts
- Investigating evolution by natural selection: Periwinkle snails simulation = the survival of the fittest (
red snails prevailed while the yellow snails were killed off quickly)
- fitness (definition & calculations)
- adaptation (definition & constraints)
- microevolution (link to genetics & definition)
- READING: Darwin’s observations and inferences
Heritability of phenotype
- Heritability of phenotype: proportion of phenotypic
variation in a population due to variation in genes.
- H= Vg/Vg+Ve
- Where: H=variation in phenotype, Vg= Variation in
genotype, Ve= Variation in environment
- Problems with this correlation: doesn’t give you context of a
cause (fixation WILL NOT equal causation)
-
Investigating Evolution by Natural Selection
- Thickest shells survived and the thin shelled snails were killed off quickly
Importance of Heritability of traits:
- Heritable characteristics will produce NO change
- Similar variation and mean
- Average will not change and therefore evolution did not occur (this means heritable traits that
include variation will cause natural selection)
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Evolution by natural selection
- Variation is necessary for evolution
- Heritability of variation is also necessary
- Survival and reproduction my vary, according to the traits
Natural Selection
Definition: Defferential survival and reproduction of individuals in a population due to the current
environmental fitness
Evolution by natural selection is OBSERVALBLE
Ex:
- Antibiotic resistance in bacteria
- Pesticide resistance in insects
- Heavy metal tolerance in plants
- Beak size in Darwin’s finches
Fitness
Definition: The degree to which an individual contributes offspring (genes / alleles) to future generations
- Absolute fitness (W): number of offspring
- Relative fitness (w): relative to others in the population
BEST GENOTYPE ALWAYS HAS A RELATIVE FITNESS EQUAL TO 1
Adaptations
Definition: traits that increase the probability that an individual with that trait will survive or
reproduce in a particular environment
Constraints on adaptations:
- Available variation for selection to act upon
- Changing environments over time
- Conflict between selection pressures (trade-offs in fitness)
(micro)Evolution
Definition: small-scale changes in genetic make-up of a population
- Refer to diagram in notes