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Lecture

Chapter 3 – Selection.docx

12 Pages
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Department
Biology
Course Code
BI110
Professor
Matthew Smith

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Chapter 3 – Selection, Biodiversity and Biosphere Biodiversity  Number of species of organisms  Life exists from ocean floor to the atmosphere Why should you care?  Biodiversity of plants, fungi, & bacteria has allowed development of therapeutic drugs Hierarchy of life  What levels of organization are between organism and cell?  What levels of organization are below that of a cell?  Organelle  Macromolecule  Molecule  Atom  Important to keep all levels of organization in mind no matter what level you’re studying  Intergrative  What happens if a perturbation is introduced at one of the levels? Diversity of Life Three Kingdoms  Bacteria  Archaea  Eukaryotes How many different species of microscopic organisms   Approx 1.5 million different species that live on earth (recorded)  Higher plants up to 300,000 (correction)  There is an incredible amount of bacteria living within the human body  There are 500 different types of bacteria living in the human mouth, only half of them are known Grouping organisms by nutrition  Troph = nourishment, Carbon = “backbone” of all organic molecules  Heterotrophs  Obtain organic carbon and energy by consuming other organisms  Humans, mammals  Autotrophs  Synthesize organic carbon molecules using inorganic carbon, CO2  Photosynthetic organisms  Photoautotrophs  Use light as source of energy for photosynthesis  Chemoautotrophs  Use reduced chemicals rich in electrons as an energy source Selection  Occurs when some force or phenomenon affects survival of individual organisms  Key elements in selection of individuals and their genetic traits:  Presence of a selective force (pressure)  Something has to be causing one thing to be selective over another, can be many different things  Genetic variation within a population  Capacity of individuals with selected trait to survive and reproduce, it is not just required tht they survive but that they can reproduce Selection Example: Evolution of Whales  In 2007, Hans Thewissen and colleagues reported evidence of ungulate (hoofed animal) ancestor closely related to whales  Lived an amphibious existence, entering water to avoid predators and going ashore to eat vegetation  At some point, started to eat fish  Explains development of aquatic mammal from terrestrial one, herbivore to piscivore  Key elements:  Genetic variation  Survival of individuals that used water to avoid predation  Selection of individuals that switch diets to fish Numbers of species of microscopic organisms harder to pin down Evolution  Gradual change in characteristics of a population of organisms over time.  Often the result of selection  Explains Unity and Diversity of all life  All organisms descended from common ancestor  share features  Species change over time due to natural selection Darwin’s Theory of Evolution  Individual organisms in a population vary in many traits which are heritable  A population often produces far more offspring than the environment can support  Limited resources means only some survive long enough to reproduce  The subset of individuals that survive and reproduce is not a random sample; individuals with favorable heritable traits are more likely to survive and reproduce, and therefore contribute more offspring to the population  Condensed version: Evolution by natural selection occurs when (1) heritable variation leads to (2) differential success in survival and reproduction  Individuals with traits that give them an advantage in local environment are more likely to survive and reproduce   Selection  Over time, the incidence of the favorable trait(s) will change in the population   Evolution  Selection  Individuals; Evolution  Population Selection Example: Evolution of Whales  In 2007, Hans Thewissen and colleagues reported evidence of ungulate (hoofed animal) ancestor closely related to whales  Lived an amphibious existence, entering water to avoid predators and going ashore to eat vegetation  the original ancestors were fairly small animals  At some point, started to eat fish  Explains development of aquatic mammal from terrestrial one, herbivore to piscivore  Key elements:  Genetic variation  Survival of individuals that used water to avoid predation  Selection of individuals that switch diets to fish  Transitional forms document changes as occurred as whales evolved from terrestrial mammals  All have distinctive ear bones unique to whales  All found in rocks formed only from ocean deposits Adaptive Radiation  Diversification of lineages of life  Organism can move into new adaptive zone after a chance innovation allows it to use environment in unique way  Adaptive radiations occur when an evolutionary breakthrough leads to diversification of life  Oxygenic Photosynthesis  Increase in O2  Allowed for aerobic respiration  Created ozone layer that allowed organisms to colonize more terrestrial environments  Changes led to explosion in diversification  Aerobic prokaryotic cells  Eukaryotic cells  Movement of plants onto land  Opened opportunities for animals Islands  Showcases of evolution and adaptive radiation  Many examples of parallel and convergent evolution  Hawaiian Islands  Violets have become shrubs
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