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BIOL 103 Lecture Notes Feb 25

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BIOL 103
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Week of February 25 [email protected] Homework:  Watch video  Read article Terminology Evolution:  Accumulation of inherited changes in populations over time leading to related species  An accepted fact in science Darwinian Fitness  Individual’s ability to survive and reproduce relative to other members of population Population  Group of individuals of one species living in one geographical area, sharing the same gene pool Species  Group of populations composed of organisms with common ancestry, sharing similar structures, functions, behaviours, etc. and able to freely interbreed in nature Community  Group of species that live together and interact in a given area Ecosystem  An interactive system composed of one or more communities and their abiotic (physical) environment Biosphere  All Earth’s ecosystems taken together Theory of Evolution by Natural Selection Proposed by Darwin and Wallace  A dominant mechanism for evolution; acknowledges that other processes contribute to evolutionary change Based on: 1. Variation in phenotype exists among individuals (size, shape, behaviour) 2. High reproductive potential means populations increase geometrically 3. Individuals compete for limited resource 4. Fit offspring with characteristics (phenotypes) matching current environment are more likely to survive and reproduce Assumptions:  NS acts on phenotypes within generation; variation must be at least partly heritable for natural selection to result in evolutionary change between generations (mechanism of inheritance was a mystery to Darwin)  Small evolutionary changes in populations occur rapidly, but complex adaptations require accumulation of multiple changes over thousands of generations – Earth’s massive age makes this reasonable (earth is much older (billions of years) than thought) Lecture 2: February 27 Evidence Supporting Evolution:  Fossil Record – stratigraphic sedimentary geology along highways represent ancient sea beds containing fossils; can see how one form had transformed into another (fossils embedded at heights of 13,210 feet)  Biogeography – distribution of life forms around earth  Selective Breeding – breeding for particular traits  Convergent Evolution – independent evolution of similar features in species of different lineages (creates analogous structures with similar form/function that was not present in previous ancestors)  Homologies – similarities o Anatomical – similarities between characteristics in different species of organisms o Developmental – a common embryotic trait o Molecular – similarities of nucleotide sequences of DNA or RNA molecules or amino sequences of proteins Fossils & Geology: Evolution Evidence  Fossils seen in layered sediments  Shows progression from unicellular organisms to today’s organisms  Shows evolution of earth’s age  Darwin spent a lot of time on expedition in South America (came across raised beach in Andes where he found many fossils) Fossil Intermediates: Example: evolution of whales – whales and hippos evolved parallel from ancient artiodactyls (cloven hoofed mammals)  Whales are evolved from terrestrial ancestors (not aquatic), ca
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