BIOL 1543 Lecture Notes - Lecture 17: Chloroquine, Homo Erectus, Long Expedition
23 Aug 2016
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DOWNLOAD 17 - EVOLUTION IN POPULATIONS
textbook reading: 13.1-13.16
MALARIA AND MOSQUITOS
anopheles the mosquitos that transmit malaria
malaria
caused by a eukaryotic parasite that is passed between mosquitoes and humans
1 million people die each year
3.2 billion people at risk
mosquitoes and evolution
in the 1960’s, WHO began campaign to eradicate malaria, by eradicating
Anopheles mosquitoes with DDT
mosquito population plummeted as did malaria cases
mosquitoes evolved resistance to DDT and malaria came back
now some mosquitoes are resistant to the 4 major classes of insecticides
in the 1950’s, chloroquine was introduced and used widely against malaria
now resistant strains to chloroquine and other antimalarials are found in many
parts of the world
populations of mosquitoes evolved resistance to DDT and populations of
Plasmodium parasites evolved resistance to drugs
CHARLES DARWIN
born February 2, 1809
did not create the concept of evolution
collected and prescribed many specimens
took 5 year voyage on the Beagle
a voyage which helped Darwin frame his theory of evolution
at the age of 22, Darwin took a position on HMS Beagle, a survey ship
preparing for a long expedition to chart poorly known stretches of the
South American coast
Darwin was the ship’s naturalist (field biologist)
spent most of his time on shore collecting thousands of specimens
of fossils and living plants and animals
kept detailed journals of his observations
particularly intrigued by the geographic distribution of organisms on
the Galapagos Islands
marine iguanas
giant tortoises
Islands are like experiments in evolution
important Darwin books
An Essay on the Principle of Population by Thomas Malthus
human population grows quickly until limiting factors, war, famine, disease,
birth control, abortion, later marriage, prostitution, decrease it
Principles of Geology by Charles Lyell
evidence for a very old earth
ADAPTATION OVER EONS
Darwin observed many organisms and saw their adaptations
he reasoned that they were all related to a common ancestor and they spread over the
earth
concluded that populations of organisms change over time to fit their environments
believed that his ideas would upset people, so he did not write until…
DARWIN AND WALLACE
Alfred Wallace a biologist exploring Indonesia
sent Darwin a letter which outlined a similar idea for evolution to
Darwin's
they published papers simultaneously in 1858
the following year, Darwin published On the Origin of Species by Natural
Selection
THE STUDY OF FOSSILS
fossils
the imprints or remains of organisms that lived in the past
documented differences between past and present organisms
reveal that many species have become extinct
Homo erectus someone that lived 1.5 millions years ago in Africa
fossil formation
conditions of formation almost always include quick burial and an accumulation
of sediments
hard parts are more likely preserved than soft parts
bone, teeth, wood, pollen, shells
after being buried in sediment and hardened into rock, organic material slowly
washes away
if air space remains - mold
if silica fills space - cast
provides strong evidence for evolution
fossil record the chronicle of evolution over millions of years of geologic
time engraved in the order in which fossils appear in rock strata
fossil record is incomplete
many of Earth’s organisms did not live in areas that favor
fossilization
fossils that did form were in rocks later distorted or destroyed by
geologic processes
not all fossils that have been preserved are accessible to
paleontologists
fossils of transitional forms support Darwin’s theory of evolution
in The Origin of Species, Darwin predicted the existence of fossils of
transitional forms linking very different groups of organisms
if his hypothesis that whales evolved from land-dwelling mammals
was correct, then fossils should show a series of changes in a
lineage of mammals adapted to a fully aquatic habitat
besides whales, many transitional series have been discovered
whales are cetaceans, a group that also includes dolphins and
porpoises
they have forelimbs in the form of flippers but lack hind limbs
if cetaceans evolved from four-legged land animals, then
transitional forms should have reduced hind limb and pelvic
bones
HOMOLOGIES
provide strong evidence for evolution
evolution is a process of descent with modification
characteristics present in an ancestral organism are altered over time by natural
selection as its descendants face different environmental conditions
evolution is a remodeling process
related species can have characteristics that have an underlying similarity yet
function differently
similarity resulting from common ancestry is known as homology
examples of homologous forelimbs
molecular comparison between diverse organisms have allowed biologists to develop
hypotheses about the evolutionary divergence of major branches on the tree of life
Darwin’s oldest hypothesis was that all life-form are related
molecular biology provides strong evidence for this claim
all forms of life use the same genetic language of DNA and RNA
the genetic code — the way RNA triplets are translated into amino
acids — is universal
homology helps explain why
early stages of development in different animal species reveal similarities not
visible in adult organisms
at some point in their development, all vertebrate embryos have
a tail posterior to the anus
