Transcript Show Darwinian Natural Selection

DESCENT WITH
MODIFICATION: A
DARWINIAN VIEW OF LIFE
CHAPTER 22
“ Nothing in
Biology makes
sense except
in the light of
evolution”
T.B.
Dobzhansky
Figure 22.2 Fossils of trilobites, animals that lived in the seas hundreds of millions of
years ago
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
Figure 22.3 Formation of sedimentary rock and deposition of fossils from different
time periods
Figure 22.4 Strata of sedimentary rock at the Grand Canyon
Figure 22.18 Charles Darwin in 1859, the year The Origin of Species was published
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
Figure 22.5 The Voyage of HMS Beagle
Figure 22.6 Galápagos finches
“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 Darwin
Descent with modification
Natural selection (the
mechanism)
Figure 22.7 Descent with modification
DARWIN’S OBSERVATIONS
Population size can lead to
struggle for existence
Individuals 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!
Figure 22.9 A few of the color variations in a population of Asian lady beetles
Figure 22.11b Artificial selection: diverse vegetables derived from wild mustard
Goldendoodle and a
liger
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.
EVIDENCE OF EVOLUTION
Biogeography –
geographical distribution of
species
Ex. Islands with similar species
to mainland
Fossil record – transitional
forms
Comparative Anatomy –
homologous structures among
different organisms
Vestigial organs –marginal, if any
importance, remnants of structures
that once served a function
Whale pelvis and leg bones and
human appendix
Comparative Embryology – most
vertebrates share common early
development (gill slits)
Molecular Biology – similar overall
DNA, similar proteins (ex.
Cytochrome c)
Figure 22.12 Evolution of insecticide resistance in insect populations
Figure 22.13 Evolution of drug resistance in HIV
Figure 22.14 Homologous structures: anatomical signs of descent with modification
Table 22.1 Molecular Data and the Evolutionary Relationships of Vertebrates
Figure 22.15 Different geographic regions, different mammalian “brands”
Figure 22.16 The evolution of fruit fly (Drosophila) species on the Hawaiian
archipelago
Figure 22.17 A transitional fossil linking past and present