BIOL 2002 Chapter Notes - Chapter 23: Molecular Evolution, Jean-Baptiste Lamarck, Macroevolution

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5 Feb 2017
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Evolution = describes the heritable change in one or more characteristics of a population from
one generation to the next
- Small scale = microevolution and large scale = macroevolution
- Species = a group of related organisms that share a distinctive form, capable of
interbreeding to form viable offspring
- Population = all the members of a species that live in the same area at the same time
and have the opportunity to interbreed
- Molecular evolution = process of evolution at the level of genes and proteins
23.1 the theory of evolution
- Empirical thought relies on observation to form an idea or hypothesis rather than trying
to understand through a nonphysical or spiritual point of view
- Work of several scientists set the stage for Darwin:
- John Ray = developed an early classification system for plants and animals
based on anatomy and physiology
- Established modern concept of a species
- Carolus Linnaeus - expanded on classification work
- George Buffon - proposed that living things change through time
- Jean Baptiste Lamarck - hypothesized that species change over the course of
many generations by adapting to new environments; organisms alter their
behaviour in response to environmental change
- His idea = inheritance of acquired characteristics
- Darwin suggested that existing species are derived from preexisting species
- The main hypothesis about geological processes in the early 19th century:
catastrophism = only catastrophic events changed the geological structure of earth
- Suggests that earth is only 6000 years old
- Uniformitarian = changes in earth are directly caused by recurring events meaning the
earth is much older than 6000 years
- Darwin’s thinking was influenced by Thomas Malthus who asserted that population size
of humans should increase linearly but it is growing exponentially; not all people can
survive
- Darwin traveled on the Beagle ship and collected information about weather, geological
features, plants, animals, fossils, rocks, minerals and indigenous people
- Natural selection changes populations from generation to generation; it is a theory of
descent with modification through variation and natural selection
- 1. Variation in traits may occur among individuals of a given species; heritable traits are
passed to offspring
- 2. In each generation, many more offspring are produced than will survive and
reproduce (resources are limited) and the process of natural selection allows individuals
with better traits to survive
23.2 evidence of evolutionary change
- Fossils shown successive evolutionary change when compared oldest to youngest
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