theories of evolution
Post on 09-Jan-2017
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Evolution and Adaptation
Early Theories, Darwin & Natural Selection
Jean-Baptiste Lamarck(France - 1744-1829)
Based theories on observations of similarities between ancient fossils and modern animals, vestigial structures and passing on of desired traits by selective breeding
Proposed than an individual gains or loses traits during its lifetime which are then passed on to its offspring.
Believed evolution is a constant process striving toward greater complexity and perfection.
Jean-Baptiste LamarckMechanisms of Change:
Law of Use and Disuse Body parts most frequently used become stronger and
more developed and parts used less are reduced. Ex. Penguins wings – Small due to disuse.
Transmission of Acquired Characteristics Qualities acquired during an organisms life time are
passed down to offspring Ex. Parents who develop strong muscles will pass strong
muscles down to offspring
Jean-Baptiste LamarckImportant contributions to evolutionary theory:Organisms change over timeOrganisms adapt to their environmentTraits found in parents are passed to offspringWhat Lamarck got wrong:Evolution tends towards perfection & complexityOrganisms are constantly evolving Acquired characteristics are passed on
Pre-Darwinian Ideas About Evolution:
Life has existed on Earth for a long timeOrganisms have changed since the dawn of lifeMany extinctions have happened since life
beganFossil evidence, embryology and comparative
anatomy show similarities between related species and suggest a common ancestor.
Mendel’s work with genetics showed how genetic elements are passed through generations
Charles Darwin(England 1809-1882)
Naturalist 1831: Embarked on 5 year
around the world voyage aboard the HMS Beagle.
Studied the diversity of life with a particular focus on the Galapagos Islands
Returned home to continue his research
1859: Published On the Origin of Species
Voyage of the Beagle
Galapagos IslandsGroup of Volcanic Islands off the coast of South
AmericaDarwin observed variation between the animals
species on each of the islands and the mainlandFamously, he observed, collected and measured
the many different species of finches found on the islands
Darwin’s Finches
Darwin’s FinchesNoticed huge variation in beak type and sizeBeak type correlated with the type of food
source on each islandHypothesized the beak type had adapted to the
type of food available in the finch habitatLed to theory of Natural Selection
Alfred Russell WallaceDarwin wasn’t the only one putting all the pieces
together…https://www.hhmi.org/biointeractive/origin-speci
es-making-theory
(30 min)
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