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…..