CAMPBELL & REECE:CHAPTER 22

Descent with Modification: A Darwinian View of Life

3 key observations about life1. Striking ways

organisms are suited to their environment

2. Unity of living things(so many common features)

3. Rich diversity of life

EVOLUTIONDESCENT WITH

MODIFICATION

EVOLUTION A CHANGE in the GENETIC COMPOSITION of a POPULATION from GENERATION to GENERATION

EVOLUTION CAN BE VIEWED IN 2 WAYS1. A PATTERN

OBSERVATIONS FROM NATURAL WORLD

2. A PROCESS MECHANISMS THAT PRODUCED

THE OBSERVED PATTERNS

ARISTOTLE(384 – 322 BCE)

DID NOT BELIEVE ORGANISMS CHANGED OVER TIME (some Greeks did)

Viewed organisms as fixed: could be arranged on ladder from least complex most complex

SCALAE NATURAE

CAROLUS LINNAEUS(1701 – 1778)

DEVELOPED BINOMIAL NOMENCLATURE

WITH A “NESTED” CLASSIFICATION SYSTEM

http://www.google.com/imgres?q=classification+of+life&start=109&hl=en&biw=1366&bih=429&addh=36&tbm=isch&tbnid=sNYuY9oEm9XeZM:&imgrefurl=http://fso2.wordpress.com/2011/07/04/a-writing-exercise/&docid=s4nrtq0D4-MX3M&imgurl=http://fso2.files.wordpress.com/2011/07/classification.jpg&w=295&h=298&ei=Z9wNUMHzOcfq0gGc3M2RDQ&zoom=1&iact=hc&vpx=459&vpy=67&dur=2404&hovh=226&hovw=223&tx=125&ty=133&sig=102733850649124752380&page=6&tbnh=121&tbnw=120&ndsp=22&ved=1t:429,r:17,s:109,i:135

LINNAEUS CLASSIFICATIONSYSTEM

PALEONTOLOGY STUDY OF FOSSILS GEORGES CUVIER (1769 –

1832)OLDER THE STRATUM OF

SEDEMENTARY ROCK THE OLDER & MORE DISSIMILAR THE FOSSILS WERE TO CURRENT LIFE

NEW SPECIES APPEARED, SOME DISAPPEARED

GEORGES CUVIER

CATASTOPHISM: EVENTS IN THE PAST OCCURRED SUDDENLY & WERE CAUSED BY DIFFERENT MECHANISMS THAN SEEN NOW

JAMES HUTTON(1726 – 1797)

Scottish Geologist Explain geologic features by

gradual mechanisms still going on now

CHARLES LYELL(1797 – 1875)

Principle of UniformitarianismMechanisms of

change are constant over time

Hutton & Lyell’s ideas influenced Darwin

Both indicated Earth had to be much older than previously believed

Darwin reasoned: slow & subtle processes could produce biological changes

Lamarck’s Hypothesis of Evolution

1st to propose mechanism of evolutionParts of body used the most become larger, stronger; parts not used deteriorate

Inheritance of Acquired Traits

LAMARCK(1744 – 1829)

EVOLUTION HAPPENS BECAUSE ORGANISMS INATELY WANT TO BECOME MORE COMPLEX

http://www.google.com/imgres?q=evolution+cartoons&num=10&hl=en&biw=1366&bih=429&tbm=isch&tbnid=XfuKw6D7Dpp4WM:&imgrefurl=http://www.cartoonstock.com/directory/o/origin_of_species.asp&docid=WBX_ljRekPQCKM&imgurl=http://www.cartoonstock.com/newscartoons/cartoonists/mly/lowres/mlyn190l.jpg&w=392&h=400&ei=Lq8nUL7SIIGg9QSepoGYDg&zoom=1&iact=hc&vpx=321&vpy=73&dur=4058&hovh=227&hovw=222&tx=94&ty=153&sig=102733850649124752380&page=4&tbnh=121&tbnw=112&start=67&ndsp=24&ved=1t:429,r:18,s:67,i:410

CHARLES DARWIN(1809 -1882)

VOYAGE of the BEAGLE1831 - 1836

Darwin’s Observations

Plants & animals in temperate zones of SA closely resembled plants & animals of temperate regions of Europe

Fossils in SA resembled living organisms in SA

GALPÁGOS

Darwin’s Observations: Descent with Modification Took note of

many adaptations saw adaptations & the origin of a new species as closely related processes

Darwin’s Finches 14 different

species each clearly adapted to a specific niche

all similar to finches on mainland SA (common ancestor)

http://www.google.com/imgres?q=Darwin's+finches&hl=en&biw=1366&bih=429&tbm=isch&tbnid=CSIbLKEGt1kFUM:&imgrefurl=http://www.historum.com/general-history/20991-charles-darwin.html&docid=r0cHf6YLgCyPHM&imgurl=http://lams.slcusd.org/pages/teachers/saxby/wordpress/wp-content/uploads/2010/02/Darwins-finches-3.jpg&w=595&h=425&ei=BLQnUJ0misz1BNiqgNgO&zoom=1&iact=hc&vpx=1049&vpy=117&dur=3786&hovh=190&hovw=266&tx=122&ty=99&sig=102733850649124752380&page=1&tbnh=81&tbnw=114&start=0&ndsp=20&ved=1t:429,r:19,s:0,i:196

Darwin’s Theory Proposed that

natural selection over long periods of time could cause an ancestral species to give rise to 2 or more descendant species

Natural Selection: a process in which individuals with certain inherited traits tend to survive & reproduce at higher rates than other individuals without those traits

The Origin of the Species by Means of Natural

Selection Darwin provided massive amounts

of evidence that descent with modification by natural selection explains :

Unity of LifeDiversity of LifeMatch between Organisms & their Environment

NATURALSELECTION

ARTIFICIALSELECTION

Darwin’s ReasoningOBSERVATIONS INFERENCES

1. There are variations of traits in populations

1. Individual with variations that are favorable will leave more offspring than one without those traits

Darwin’s ReasoningOBSERVATION INFERENCE

2. Species produce more offspring than can survive

2. overpopulation leads to competition, those with traits that will help them survive reproduce more passing along favorable traits

SURVIVAL of the FITTEST

Over time natural selection increases the

match between organisms & their environment

When the environment changes natural selection may result in adaptations that give

rise to a new species

Natural Selection in response to invasive species

BALLOONVINE

GOLDENRAIN TREE

SOAPBERRY BUGS SEEDS BURIED

DEEPER IN PODS OF NATIVE PLANT, BALLOON VINE

BUGS THAT FEED ON INVASIVE GOLDENRAIN PODS NOW HAVE SHORTER BEAKS

CONCLUSION CHANGING THE

ENVIRONMENT CAN RESULT IN EVOLUTION BY NATURAL SELECTION FOR MATCHING BEAK SIZE

DRUG-RESISTANTBACTERIA

Normal for 1 out of 3 people to have Staph aureus on skin

MRSA (methicillin-resistant staph

aureus)Can be fatal

Developing drug-resistance

Rise of MRSA hospital acquired infections 1993 - 2005

From study done in Atlanta area in 2006

Soapberry bug & MRSA both examples of

1. natural selection does not “create” it “selects” for variants already present in population

2. natural selection depends on time & place

HOMOLOGY SIMILARITY RESULTING FROM

COMMON ANCESTORS

Homologous Structures: Embryology

Similarities in early stages of development suggest common ancestryAt some point in development

all vertebrates have a tail

VESTIGIAL STRUCTURES REMNANTS OF

FEATURES THAT WERE IMPORTANT IN EVOLUTIONARY ANCESTOR

Molecular Homologies All life forms use DNA & RNA Genetic code is universal Some human genes code for

exact same protein as bacterial gene +/- have same function

Some organisms carry “vestigial genes”

Evolutionary Tree Can organize organisms with

shared characteristics in nested groups Deepest layer all living things

share Each successive smaller group

have their own unique homologies

Evolutionary Trees are

hypotheses that summarize our current understanding of patterns of descent

Convergent Evolution The independent evolution of

similar features in different lineages

http://www.google.com/imgres?q=convergent+evolution+examples&hl=en&biw=1366&bih=429&tbm=isch&tbnid=aV20EqZxxZu_pM:&imgrefurl=http://socraticmama.com/secular-parenting/evolution&docid=E7ORy6M3AJkg1M&imgurl=http://socraticmama.com/wp-content/uploads/2012/02/converg2.gif&w=327&h=178&ei=RhMpULKOIOO-0AG1u4GADA&zoom=1&iact=hc&vpx=619&vpy=158&dur=8658&hovh=142&hovw=261&tx=102&ty=120&sig=102733850649124752380&page=1&tbnh=68&tbnw=125&start=0&ndsp=20&ved=1t:429,r:5,s:0,i:101

http://www.google.com/imgres?q=convergent+evolution+examples&hl=en&biw=1366&bih=429&tbm=isch&tbnid=ys2WDW0vzh7-8M:&imgrefurl=http://www.duq.edu/sepa/regmed/evolution/aspects.shtml&docid=yMWHLXVwLJgXAM&imgurl=http://www.duq.edu/sepa/regmed/images/Human-Octopus-eye.png&w=400&h=288&ei=RhMpULKOIOO-0AG1u4GADA&zoom=1&iact=hc&vpx=406&vpy=117&dur=10181&hovh=190&hovw=265&tx=108&ty=142&sig=102733850649124752380&page=2&tbnh=123&tbnw=180&start=20&ndsp=21&ved=1t:429,r:2,s:20,i:156

Analogous Features are seen in

species that share similar structures but not common ancestry

The Fossil Record Shows:1. past organisms differ from

current ones2. many species have become

extinct3. the evolutionary changes that

have occurred in various groups of organisms

BIOGEOGRAPHY The GEOGRAPHIC DISTRIBUTION

of ORGANISMS Influenced by:

Continental Drift 250 million yrs ago all land masses joined Pangea

200 million yrs ago split began 20 million yrs ago looked close to what we have today

Continental Drift Understanding

continental drift scientists look for fossil evidence explained by the movement of land masses

Summary: 4 Types of Evidences for Evolution

1. Direct Observations1. Effect of invasive species2. Drug-resistance in bacteria

2. Anatomical Similarities1. Homologous & Vestigial Structures2. Universal Genetic Code

3. Fossils4. Biogeography