Title: Lecture 10 BIOL L100 Indiana University Southeast David Partin, Instructor
1Lecture 10BIOL L100 Indiana University
SoutheastDavid Partin, Instructor
2Todays Plan
- Announcements/Questions
- Lecture 10 Evolution
- Video clips
- One Minute Paper
- Introduce Case Studies 3 4
3Evolution Ch 17-18
The modern horse, Equus, and its Oligocene
ancestor, Mesohippus.
4Charles Darwin (1809-1822)
Evolution has 2 components (1) descent from a
common ancestor and (2) adaptation to the
environment
5Pre-Darwinian Theories
- Creationism dominated the school of thought
- Carolus Linnaeus (1707-78)
- taxonomist famous for binomial nomenclature (e.g.
Homo sapiens) - Each species had an ideal structure and a place
in the scala naturae (uncomplicated ?
complicated) - Count Buffon Erasmus Darwin
- Conceded that species do change over time
6Pre-Darwinian Theories
- Georges Cuvier (1769-1832)
- founder of paleontology
- Did not support the idea of evolution
- Catastrophism
- Jean-Baptiste de Lamarck (1744-1829)
- Supported the idea of evolution
- explained evolution with inheritance of
acquired characteristics
7Charles Darwin
- British scientist, also trained at seminary
- At age 22, boarded HMS Beagle and sailed around
the world studying wildlife and geography
(1831-1836) - Began to formulate hypothesis on evolution of
species based on observations during this journey
8Charles Darwin
- Observed geology/fossils
- Agreed with James Huttons ideas on slow, steady
geographical change - If earth is old, then that means there has been
enough time for evolution to take place. - Biogeography
- Animals adapt to their environments through
natural selection.
9Natural Selection
- Members of a population exhibit random but
inherited variations. - Individual struggle for existence encourages
survival of the fittest - These fit individuals have characteristics
allowing them to acquire more resources and to
survive reproduce.
10Think-Pair-Share
- Natural Selection
- Survival of the fittest
- Examples?
- How this works
- Think-1 minute
- Pair-1 minute
- Share
11Artificial selection
12Darwins observations made him think.
His thoughts congealed into his hypothesis of
evolution.
13Evidence for Evolution
- A hypothesis is strengthened when many different
lines of evidence support it. - Darwins evolutionary hypothesis soon became a
scientific theory. - Alfred Wallace deserves credit, too.
14Evidence for Evolution
- Fossil record
- History of life
- Opportunity to trace descent
- Biogeography
- Distribution of organisms on Earth is explainable
by assuming organisms evolve in one locale. - Comparative anatomy
- Similarities/differences in structure can
indicate relatedness - Comparative biochemistry
- All organisms have certain biochemical molecules
in common - Differences indicate degree of relatedness
15Glyptodon, seen only in fossil remains is
structurally very similar to the living armadillo.
Archaeopteryx- transitional fossil between birds
and reptiles.
16Evolutionary history of Equus
Information obtained through fossil record
17The pace of evolution
18Biogeographical evidence
All the marsupials in Australia presumably
evolved from a common ancestor. Each type is
adapted to a different way of life.
19Anatomical evidence
Homologous structures anatomically similar
because they are inherited from a common ancestor.
Human embryo
20Anatomical evidence
Analogous structures serve the same function, but
they are not constructed similarly, nor do they
share a common ancestry.
21Anatomical evidence
- Vestigial structures
- Retained, but useless
- Humans have a tailbone, but no tail
- Bird species with reduced wings
- Some snakes have remnants of legs
- Hind leg bones in whales
- http//www.livescience.com/animalworld/top10_vesti
gial_organs.html
22Biochemical evidence
23Cause of evolution
- Genetic mutations
- Gene flow (or gene migration)
- Nonrandom mating
- Genetic drift
24Gene Flow
25Only certain members of a population reproduce,
passing on their genes. The gene pool in the
next generation may be significantly different
from the previous generation.
26Founder Effect
Non-random mating (inbreeding) can result in
genetic drift.
27Natural selection is connected to genetics.
28Despite natural selection, variation is
maintained. Mutations occur, as well as gene
flow. Heterozygotes are a repository of
recessive alleles. In sickle cell disease, the
heterozygote is more fit (normal hemoglobin and
malaria protection) so both homozygotes are
maintained in the population.
29Speciation
- 1 species becomes 2 or more
- No longer able to interbreed
- A species is defined according to interbreeding.
With few exceptions, a member of a species will
only mate with a member of the same species.
30In order to be considered distinct species,
individuals must lose the ability to successfully
interbreed. This can be accomplished by several
different methods.
31Temporal isolation
322 types of speciation (1) Allopatric speciation
requires a geographical barrier (2) Sympatric
speciation no geographic barrier
33Adaptive radiation resulting from allopatric
speciation
Hawaiian Honeycreepers
34Human Evolution
- Keep an open mind.
- Observe the evidence objectively, leaving
opinions for another time. - Try to put the evolution conflict in perspective.
35These characteristics especially distinguish
primates from other mammals
- Opposable thumb (and in some cases, big toe)
- Nails (not claws)
- Single births
- Binocular vision
- Expanded, complex brain
- Emphasis on learned behavior
36Evolution of Primates
37Monkey skeleton compared to Proconsul skeleton.
The apelike Proconsul, which was prevalent in
Africa during the Miocene epoch, is believed to
be ancestral to todays hominoidsapes and
humans.
Comparison of a monkey skeleton with that of
Proconsul shows various dissimilarities,
indicating that Proconsul is more related to
todays apes than to todays monkeys.
38Adaptations for standing. (a) Human skeleton
compared to (b) chimpanzee.
39Fossils in the genus Homo have larger brains than
those in the genus Australopithecus. Also, their
jaws and teeth are more humanlike, and various
examples of their tools have been found. The
length of time each species existed is indicated
by the vertical gray lines. Notice that there
have been times when two or more hominids existed
at the same time. Therefore, human evolution
resembles a bush rather than a single branch.
It is not known whether A. afarensis or A.
africanus is the direct ancestor of humans.
Human Evolution
Lucy! 3.18 million years old.
40Evolution of modern humans. (a) The
multiregional continuity hypothesis proposes that
Homo sapiens evolved separately in at least three
different places Asia, Africa and Europe.
Therefore, continuity of genotypes and phenotypes
is expected in each region, but not between
regions. (b) The out-of-Africa hypothesis
proposes that Homo sapiens evolved only in
Africa then this species migrated and supplanted
populations of Homo in Asia and Europe about
100,000 years ago.
41(A) Neanderthals. This drawing shows that the
nose and mouth of Neanderthals protruded from
their faces, and their muscles were massive.
They made stone tools and were most likely
excellent hunters.
A
(B) Cro-Magnons are the first to be designated
Homo sapiens. Their tool-making ability and
other cultural attributes, such as their artistic
talents, are legendary.
B
(C) (a) Modern human ethnic groups. Some of the
differences between the three prevalent ethnic
groups in the United States may be due to
adaptations to the original environment. (b) The
Massai live in East Africa. (c) Eskimos live near
the Arctic Circle.
C
42Human Variation
- Skin color
- Darker skin protects against UV radiation from
the sun - Lighter skin ensures vitamin D production in the
skin when the UV intensity is low - Body build
- Cold-dwelling animals bulkier build, shorter
limbs and digits (e.g. Eskimo) - Hot-dwelling animals slighter build, elongated
limbs and digits (e.g. Massai) - Intelligence no significant disparity among
ethnic groups
43Human Variation
- Comparative study of mitochondrial DNA among 7
major geographical groups - Caucasians, black Africans, mongoloids, south
Asian Aborigines, Amerinds, Oceanians, and
Australian Aborigines - 85 of genetic variation occurs among individuals
of the same ethnic group, rather than between
ethnic groups. - Genetic variations due in part to adaptations to
local environments.
44Conclusion
- We are one species! All humans! All Homo sapiens!
- All ethnic groups evolved from the same single,
ancestral population. This probably occurred
within the last one million years.
45Thanks for your attention!Any questions?
46Video Clips
- Evolution documentary
- Walking with Cavemen
47- Case Study 3 Ethics in Science
- Movie GATTACA (1997)
- Starring Ethan Hawke and Uma Thurman
- Choose a controversial topic in science pros vs
cons - Case Study 4 The Darwin Debate
- Article discusses evolution vs. intelligent
design debate - Movie Inherit the Wind (1960)
- Starring Spencer Tracy
- Based on true events
48Preparation for Lecture 11
- Read/Skim chapters 19-21
- Keep up with Oncourse quizzes!