Lecture 1: Introduction.docx
Course CodeBIO SCI 94
ProfessorNancy Aguilar- Roca
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Lesson 1: Introduction Pg. 11-25
•evolution: the idea that the organisms living on Earth today are the modified descendants of
•From smallest to greatest:
Species Genus Family Order Class Phylum Kingdom Domain
Three Domains of Life:
1. Domain bacteria: prokaryotes; has multiple kingdoms
2. Domain Archaea: prokaryotes; lives in extreme environments, such as extreme salty lakes and
boiling hot springs; has multiple kingdoms
3. Domain Eukarya: All the eukaryotes (organisms with eukaryotic cells); includes 3 kingdoms of
multicellular eukaryotes: kingdom Plantae, Fungi, and Animalia.
Charles Darwin and the Theory of Natural Selection
-“descent with modification”
-came up with theory through observations:
•individuals in a population vary intheir traits, many of whichseem to be heritable
(passedon from parents to off-spring)
•a population can produce far moreoffspring than can surviveto produce offspring of
theirown, making competition inevitable
•species generally suit their environment—they adapt.
The Tree of Life
Darwin proposed that over long periods of time, natural selection could cause ancestral species to
give rise to two or more descendant species
Example: if one population fragmented into several subpopulations isolated in different
environments. In those separated areas of natural selection, one species could gradually radiate
into multiple species as the geographically isolated population adapted over many generations to
different sets of environmental factors.
In studying nature, scientists make observations and then form and test hypotheses:
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