– Adaptations –….organisms have adapted to environmental changes
and have also changed through time. CHANGE = Evolution
– Evolution (Darwinian and its modern synthesis) = a scientific revolution
Darwin’s Contribution - Darwinian Evolution
– Change over time is an old idea
– The voyage of the Beagle
o Observations that changed biology
– Populations of organisms unique to certain parts of the world (biogeography)
– armadillos and sloths of South America
Darwin’s Contribution - Darwinian Evolution
• The Galápagos Islands - a living laboratory of evolution
• Key Observations
– organisms which share a common ancestor
– morphological adaptations to occupy certain niches
– finches and tortoises
Darwin’s Contribution - Darwinian Evolution
– Natural Selection (The Origin of Species, 1859)
– Darwinian Evolution– Natural Selection: organisms that are the
most fit survive to pass on traits to offspring
– variation among offspring
– adaptations – fitness
– Darwing didn’t understand the mechanisms
Modern Synthesis – Genes, DNA, and Chromosomes
- discovery of the particles (genes) that made up the molecule DNA
- double helix structure - each 3 bases along the DNA form a gene; triplet code:
codes for a particular amino acid
- Genes can be altered – change in the code during replication = point
mutations = source of variation
• What Darwin didn’t get
– Sex
– Recombination and mutation