Download Evolution

Descent with modification
 A. Change in species over time
 B. Change in gene frequencies from
generation to generation
 C. A Process of change
 A. Natural Selection – Requires
 1. Genetic diversity
 2. differential reproduction by individuals
with the most fit genes
 3. Increase in those genes within population
 A. Carolus Linnaeus (1707-1778)
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1. Binomial Nomenclature Genus species
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2. nested groupings into increasingly
specific categories based on morphology
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3. K P C O F G S
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4. Kingdom, phylum, class, order, family,
genus, species
5. now we have added Domains
 B. Stratification –
 1. rock laid down in layers
 2. oldest at bottom
 3. fossils in strata show when organisms lived
 order of appearance (now isotopic dating)
 4. Older fossils more dissimilar to modern
 5. species appear and disappear
 6. Cuvier (1769-1832) catastrophism
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a. catastrophes destroyed species in an area
new species moved in
 C. Lamarck (1744-1829)
 1. one of many to propose that life evolves as
environments change
 2. first to propose mechanism
 3. compared fossils showing lines of descent
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a. chronological fossils show gradual change
b. leading to modern species
c. use and disuse
d. inheritance of acquired characteristics
 A. Charles Lyell ( 1797 – 1875)
1. Geologist
 2. Theory of Uniformity
 3. Natural processes observed today are the
same as processes acting in the past
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4. The rate of processes today mirror those of
the past
5. contradicted young earth theory
 B. Thomas Malthus: economist
1. war and famine result from human
overpopulation
 2. Other organisms also produce more
individuals than can survive
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 C. Alfred Wallace (1823-1913)
1. first to publish Natural Selection as a
mechanism for evolution
 2. ideas nearly identical to Darwin’s
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 D. Charles Darwin ( 1809 – 1882)
1. Origin of Species
 2. extensive evidence of
natural selection
3. Lylle, Darwin & Wallace
convinced most scientists with in 10 years
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 Three Main Ideas
 1) Unity of Life: shared characteristics
attributed to shared common ancestor
 2) Diversity of Life: due to descent with
modification
 3) Match between organisms and
environments: due to adaptation
 Observations in blue
 Followed by associated Inference
 Inferences in yellow
 A. Artificial selection: selective breeding
can produce visible change over a life-time
 A. If artificial selection can produce rapid
change….then natural selection could produce
dramatic change given enough time
 * Lyell suggested a time line of millions of years
 B. Organisms produce more offspring than can
survive (Malthus)
 B. Survival most likely for those best fit to their
environment.
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 C. members of a population vary in Inherited
traits
 C. If only some organisms can survive then
 those with best traits are more likely to survive
 So good genes accumulate in population…
 Genetic make-up of population ∆ over time =
 Evolution!
Mammal neck bones =7
Bird neck bones 13-25
 Giraffe neck vertebrae
 Birds with short neck
are each elongated…
 No new bones added
have curve in neck
vertebrae…
 not fewer vertebrae
 A. Fitness:
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ability to pass on its genes
1. survive
2. mate
3. fertile offspring live to reproduce
 B. Adaptation: inherited traits that improve
fitness in a given environment
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1. individuals can NOT adapt its genetic!!
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2. only populations adapt over generations
 A. speciation – one species branches into 2 new
species (ancestral species gone)
 B. Adaptive radiation –1 species gives rise to
many species (common after mass extinctions)
 1. individuals disperse to new environments
 2. adapting to new environment causes them to
change
 C. Universal Common Ancestor – all started
from some single celled organisms
 1. ‘the unity of life’
 2. universal genetic code DNA, RNA
 3. shared genes (homeotic genes)
 4. Semiconservative replication
 5. transcription/translation (Met)
 6. shared proteins(DNA and RNA polymerase)
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 A. Direct observation – species change over time
 1. Bacteria develop antibiotic resistance
 2. Weeds develop resistance to roundup
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Figure 1. Number of weed species with glyphosate resistant populations and number of
states with glyphosate-resistant weed populations.
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Source: Heap, 2009.
 3. Grant’s finch research
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a. recorded beak depth of all finches on an
island over 30 years
 B. Homology: similarities resulting from
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common ancestor
1. Homologous Structures
a. anatomical features
b. same underlying structure
c. may have adapted to different function
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d. embryo homology may be lost in adult
1. pharyngeal arches – all chordates
2. post anal tail – all chordates
 2. Vestigial Structures : inherited from
ancestor but no longer used
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a. explains presence of useless structures
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b. pelvic girdle & femur in whale & snake
 C. Human vestigial structures
 3. molecular homologies: same DNA/ protein
a. all organisms homologous DNA structure
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b. Many homologous DNA genes
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1. some have developed a new function
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2. some still same function
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a. genes for ribosome subunits
homologous between humans and bacteria
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3. some genes vestigial
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 A. document formation of new species by
sequential fossils
 1. Geographic distribution of species
 2. endemic species :
 a. ancestor from mainland
 b. adaptive radiation
 c. island species all share
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1. homologous structures
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2. homologous DNA/proteins
 d. homologies shared with a mainland species
 3. Similar species from different continents not
genetically similar
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(convergent evolution)