Chapter 9 Evolution Barron’s Book
Mar 26, 2015
Chapter 9 Evolution
Barron’s Book
Microevolution
House sparrows have adapted to the climate of North America, ]
mosquitoes have evolved in response to global warming,
and insects have evolved resistance to our pesticides.
These are all examples of microevolution — evolution on a small scale.
Macroevolution
Anagenesis vs. Cladogenesis
Evidence for Evolution
We will discuss FIVE
Fossil Record Transitional fossils
Comparative Anatomy
Homologous
Analogous
Vestigial
Comparative Embryology
Comparative Embryology
Comparative Embryology
Molecular Biology
Cytochrome C – polypeptide (amino acid sequence)
Biogeography
Biogeography
Most of the 140 species of marsupials in Australia are found nowhere else in the world.
Worldwide Distribution of the Order Marsupiala
Common NamesScientific
Name
No. Genera
No. Species
Distribution
Oppossums Didelphidae 12 70 Americas
Marsupial Mice, Marsupial Cats, Tasmanian Devil
Dasyuridae 14 50 Australasia
Tasmanian WolfThylacinida
e1 1 Tasmania
Numbats/Banded AnteatersMyrmecobii
dae1 1 Australia
BandicootsPeramelida
e8 18 Australasia
Shrew OppossumsCaenolestid
ae3 7 South America
Possums, Cuscuses, Gledero, Ringtails
Phalangeridae
13 40 Australasia
Noolkanger or Honey PossumTarsipedida
e1 1 Australia
KoalasPhoscolarat
idae1 1 Australia
Wombats Vombatidae 2 4 Australia
Kangaroo/Wallabies, Potoroos, Rat Kangaroos
Macrophodidae
15 47 Australasia
Bi-nomial nomenclature Homo sapiens Lizardus Dominicanus
Cuvier
Hutton and Lyell
Lamarck“acquired characteristics”
Alfred Wallace
Published an essay discussing natural selection, prompting Darwin to publish his book
Charles Darwin
Early 1840’s theory is worked out Publishes “On the origin of
Species” in 1859
4 tenets of natural selection
Over population
Advantageous traits
Types of Selection
Stabilizing
MRSA - The deadliest form of Staph MRSA stands for methicillin-resistant staphylococcus aureus Staph bacteria that are resistant to the action of methicillin and related
antibiotics are referred to as MRSA MRSA are not only resistant to all penicillin-like antibiotics, but they are often
resistant to many other types of antibiotics as well. Infections with MRSA can be costly and difficult to treat because of limited
antibiotic options. The proportion of staph infections that are methicillin-resistant has been steadily
increasing, especially in the last 15-20 years. By 2003, the percentage of MRSA among all staph isolates had risen three-fold to
38.6%. Almost 40% of staph found is MRSA now! MRSA is spread by physical contact, person to person, or person to contaminated
object MRSA symptoms for the most part, not different from any other staph infection Diagnosis is confirmed by identifying the bacteria grown in a laboratory culture
from a sample. The sample may be from a sterile site, such as blood or cerebrospinal fluid (CSF), or from a non-sterile site such as a draining lesion or a swab of the back of the nose.
Sexual Selection
sexual dimorphism bestows upon the females a large, pink, pillowy buttocks sexual dimorphism bestows upon the females a large, pink, pillowy buttocks
Artificial Selection
Sources of Variation in Population
100’s of breeds of dogs…1 species, demonstrates the tremendous potential for variation
…extent of variability, is a major determinant of capacity for evolution
Balanced Polymorphism
Two phenotypes in one species, each better for its own environment
Mutations
Provide new alleles in gene pool Adaptations
Sexual Reproduction
Provides variation
Independent assortment of chromosomes
Crossing Over
Random Fertilization A zygote is formed
by the random union of independently-produced gametes.
For humans, the number of different gametes is 223 * 223, or 8,388,6082, giving 70,368,744,177,664 (70 trillion) possible combinations.
Outbreeding
Mating organisms that are not closely related….
Is that bad or good?
Promotion of Outbreeding
Flowering plants..male and female parts mature at different times
Lions---dominant male chases away young maturing males…
Diploidy 2n condition, whole other set of
genes that could be an advantage when conditions change
Heterozygote superiority
Hybrids have an advantage ** Population retains greater variation Ex sickle cell anemia Ss- no sickle cell, and resistance to
malaria SS no sickle cell, die from malaria ss has sickle cell, and may die from
that
Frequency Dependent Selection Minority advantage Decrease frequency of
more common phenotypes Ex.) Search
image….predators are used to chasing prey that looks a certain way, if you look different you and your young will survive…
Evolutionary Neutral Traits
Bloodtype Fingerprint variation Where from? Why? Function? ….all unknowns
Causes of Evolution
Genetic Drift: change due to chance Bottleneck effect (fire, earthquake,
flood)…
Founder effect
Small population breaks away from a larger one. Rarer alleles are over represented…..
Amish 1770’s German population, extreme isolation, and intermarriage
Gene Flow
Movement of alleles in or out of population
Migrations
Mutations
Changes in genetics material
Nonrandom mating
Individuals chose mates for a specific reason
http://www.pbs.org/wgbh/evolution/library/01/6/quicktime/l_016_08.html
Natural selection
Environment changes Those who are better adapted to it “are selected for” They survive They reproduce and those genes
are passed on…
Sources of Stability in populations
Hardy and Weinberg Stable population would require 5
things large Isolated No mutations Mating random No natural selection
This is purely hypothetical, it CANNOT exist
Hardy Weinberg Equation
Calculate frequencies of alleles in population
P dominant allele Q recessive allele Problems 1, 2, 3 – go over together
Speciation
To be of the same species…. Potential to interbreed in nature Produce fertile viable offspring
Allopatric speciation
Caused by geographic isolation
Sympatric Speciation
Polyploidy- more than 1 set of chrom
Habitat isolation- Behavioral isolation Temporal isolation Reproductive isolation
Plants that are polyploidy CANNOT breed with plants that have the normal number of chromosomes
Habitat Isolation
Behavioral Isolation
Temporal Isolation
Reproductive Isolation
Anatomical incompatibility Small male dog and large female
dog cannot mate Prezygotic barriers- prevent
mating Postzygotic barriers- mating occurs
but offspring is infertile
Patterns of Evolution
Divergent
Convergent
Convergent
Parallel Evolution
Coevolution
Adaptive Radiation
Macroevolution
Gradualism- organisms descended from a common ancestor gradually, in a linear and branched fashion.
Prob: A lot of missing links haven’t been found
Punctuated Equilibrium
Gould and Eldridge- new species appear suddenly after long periods of stasis…
See figures page 183
Origin of Life
Earth age 4.6 billion years Ancient atmosphere, had many
gases but lacked free oxygen UV rays and lightening Mimicking early Early Earth….
Mitochondrial DNA, is inherited from the mother…..