bio lecture 3 - Lecture 3 Origins of the Species I I....

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Lecture 3 – Origins of the Species I I. Review: Geologic timescale - 4.5 - 3.9 BYA – First cells - 3.9-3.5 BYA – First prokaryotes - 2.7 BYA – Oxygen Revolution - 2 BYA – Eukaryotes - 1.5 BYA – Multicellularity - ~700 MYA – first animals - 540 MYA Paleozoic Era - 540 MYACambrian – Explosion of animal diversity - 488 MYA Ordovician – colonization of land by small plants and animals - 444 MYA Silurian – Evolution of vascular plants (e.g. forests) - 416 MYA Devonian – colonization of land by tetrapods (i.e. vertebrates) - 250 MYA – Mesozoic Era (age of dinosaurs) - 65 MYA – Cenozoic Era (age of mammals) II. What is Evolution? A. Evolution - change in allele frequency in a population over time 1. Locus - specific location of a gene / DNA sequence on a chromosome 2. Allele - variant of DNA sequence / locus 3. Population - a group of interbreeding individuals 4. Gene pool - total aggregate of alleles in a population III. How do populations evolve? A. Mechanisms that cause allelic change
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bio lecture 3 - Lecture 3 Origins of the Species I I....

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