descent with modification: a darwinian view of life chapter 22
Post on 19-Dec-2015
227 Views
Preview:
TRANSCRIPT
HISTORICAL CONTEXT
Carl Linnaeus (1707-1778) – founder of taxonomy (scientific name) grouped similar species into same genus
Georges Cuvier (1769-1832) – catastrophism – different species in layered rock due to catastrophic events like floods
James Hutton (1726-1797) – gradualism – profound change is a cumulative product of slow but continuous process; ex. Rivers making canyons
Charles Lyell (1797-1875) – uniformitarianism – geological process have not changed throughout Earth’s history
Jean Baptiste Lamarck (1744-1829)- thought acquired characteristics can be passes on to offspring
CHARLES DARWIN (1809-1882)
Worked on the HMS Beagle in 1830’s
Observed and collected thousands of different species
Galapagos Islands (west of S. America) most interesting
“The Galápagos tortoise (or Galápagos giant tortoise), is the largest living tortoise, endemic to nine islands of the Galápagos archipelago. Adults of large subspecies can weigh over 300 kilograms (660lb) and measure 1.2 meters (4 ft) long. Although the maximum life expectancy of a wild tortoise is unknown, the average life expectancy is estimated to be 150-200 years.”Source: en.wikipedia.org/wiki/Gal%C3%A1pagos_tortoise
Darwin read Lyell’s Principles of Geology and felt age of earth was much older than previously thought
1844 Darwin wrote essay on the origin of species
1858 – Alfred Wallace sends manuscript to Darwin about Natural Selection
Lyell presented Wallace’s paper as well as Darwin’s 1844 essay to scientists
1859 The Origin of Species published by DarwinDescent with modificationNatural selection (the
mechanism)
DARWIN’S OBSERVATIONSPopulation size can lead to
struggle for existenceIndividuals who inherited
characteristics best fit for environment are likely to have more offspring than less fit individuals
Leads to gradual change in a population
NATURAL SELECTION
A population evolves, not an individual!
Acquired characteristics may be adaptable but are not inherited!!
The environment does not create a best fit characteristic, but selects for it!
AP:April. 29, 2005 ST. THOMAS, Barbados - It's male. But what is it? A zonkey? A deebra? That's the debate in Barbados since a zebra gave birth to a foal sired by a donkey.
Goldendoodle and a liger
EVIDENCE OF EVOLUTIONBiogeography – geographical
distribution of speciesEx. Islands with similar species
to mainlandFossil record – transitional
formsComparative Anatomy –
homologous structures among different organisms
Vestigial organs –marginal, if any importance, remnants of structures that once served a functionWhale pelvis and leg bones and
human appendixComparative Embryology – most
vertebrates share common early development (gill slits)
Molecular Biology – similar overall DNA, similar proteins (ex. Cytochrome c)
top related