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122 Cards in this Set

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Adaptive Radiation
Adaptive radiation describes the rapid speciation of a single or a few species to fill many ecological niches. This is an evolutionary process driven by mutation (heritable/genetic variation) and natural selection.

Contents [hide]
1 Causes of adaptive radiation
1.1 Opportunity
1.2 Extinction
2 Adaptive radiation in popular culture
3 References

[edit] Causes of adaptive radiation

[edit] Opportunity
Isolated ecosystems, such as archipelagos and mountain areas, can be colonized by a species which, upon establishing itself, undergoes rapid divergent evolution. Monotremes and marsupials are examples of geographic isolation. Monotremes evolved before the evolution of placental mammals, and they are found today only in Australia, an island. Marsupials, which also evolved before the appearance of placental mammals are also common in Australia. In Australia, marsupials evolved to fill many ecological niches that placental mammals fill on other continents.
Artificial Selection
Artificial selection is the intentional breeding of certain traits, or combinations of traits, over others. It was originally defined by Charles Darwin in contrast to the process of natural selection, in which the differential reproduction of organisms with certain traits is attributed to improved survival and reproductive ability in the natural habitat of the organism. Artificial selection that produces an undesirable outcome from a human perspective is sometimes called negative selection (but note that this term has a better-established meaning as a type of natural selection).

Charles Darwin originally coined the term as an illustration of his proposed wider process of natural selection. He noted that many domesticated animals and plants had special properties that were developed by intentionally encouraging the breeding potential of individuals who both possessed desirable characteristics, and discouraging the breeding of individuals who had less desirable characteristics.
Behavioral Isolation
Sexual attraction between males and females of a given species may be weak or absent. In most animal species, members of the two sexes must first search for each other and come together. Complex courtship rituals then take place, with the male often taking the initiative and the female responding. This in turn generates additional actions by the male and responses by the female, and eventually there is copulation, or sexual intercourse (or, in the case of some aquatic organisms, release of the sex cells for fertilization in the water). These elaborate rituals are specific to a species and play a significant part in species recognition. If the sequence of events in the search-courting-mating process is rendered disharmonious by either of the two sexes, then the entire process will be interrupted. Courtship and mating rituals have been extensively analyzed in some mammals, birds, and fishes and in a number of insect species (see reproductive behaviour).
Bottle Neck Effect
The bottleneck effect is a genetic drift resulting from reduction of a population, typically by a natural disaster, so that the surviving population is no longer genetically representative of the original population.
Comparative Biochemistry
Comparative biochemistry is the study of differences in chemical (metabolic) processes among species of animals. For example, the difference between carnivorous species of animals and herbivores is included in comparative biochemistry.

Comparative biochemistry is used by scientists studying Charles Darwin's theory of evolution. Comparative Biochemistry may be used as evidence for Darwin's theory of evolution if the two animals being compared share similarities, as that would indicate a common ancestry.
Comparative Embryology
All vertebrate embryos follow a common developmental path due to their common ancestry. All have a set of very similar genes (the homeobox genes) that define their basic body plan. As they grow, the differences that will distinguish the embryos as adults become more and more apparent. The study of this development can yield insights into the process of evolution.
Who is Cuvier?
Catastrophism - 1800. Fossils were relics or impressions of the past. The earth has had a succession of flora & fauna, but no change has occurred.

Without a doubt, Georges Cuvier possessed one of the finest minds in history. Almost single-handedly, he founded vertebrate paleontology as a scientific discipline and created the comparative method of organismal biology, an incredibly powerful tool. It was Cuvier who firmly established the fact of the extinction of past lifeforms. He contributed an immense amount of research in vertebrate and invertebrate zoology and paleontology, and also wrote and lectured on the history of science.
What is the Darwinian Theory?
Natural selection is the evolutionary process by which favorable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavorable traits that are heritable become less common. Natural selection acts on the phenotype, or the observable characteristics of an organism, such that individuals with favorable phenotypes are more likely to survive and reproduce than those with less favorable phenotypes. If these phenotypes have a genetic basis, then the genotype associated with the favorable phenotype will increase in frequency in the next generation. Over time, this process can result in adaptations that specialize organisms for particular ecological niches and may eventually result in the emergence of new species.

Natural selection is one of the cornerstones of modern biology. The term was introduced by Charles Darwin in his groundbreaking 1859 book The Origin of Species[1] in which natural selection was
What is DNA Recombination?
Genetic recombination is the process by which combinations of alleles at different loci move position within a genome. This commonly occurs during meiosis, leading to offspring having different combinations of genes from their parents. Such shuffling is usually the result of recombination within two different copies of a chromosomes (crossing over). As genes are widely-spaced within most genomes, recombination occurs frequently. However, as recombination is random, it will occasionally bring together parts of different genes, resulting in the production of a novel allele through the rearrangement of existing genetic variation. In evolutionary biology, genetic recombination is thought to have many advantages including that of allowing sexually reproducing organisms to avoid Muller's ratchet.
Directional Selection
Directional selection is a natural selection that favors extreme over intermediate phenotypes
Disruptive Selection
Disruptive selection is a type of evolution that simultaneously favors individuals at both extremes of the distribution. When disruptive selection operates, individuals at the extremes contribute more offspring than those in the center, producing two peaks in the distribution of a particular trait.

Suppose there is a population of rabbits. The color of the rabbits is governed by two incompletely dominant traits: black fur represented by “B” and white fur represented by “b”. A rabbit with the genotype of “BB” would have a phenotype of black fur, a genotype of “Bb” would have gray fur (a display of both black and white) and a genotype of “bb” would have a phenotype of white fur.

If this population of rabbits were put into an area that had very dark black rocks as well as very white colored stone, the rabbits with black fur would be able to hide from predators amongst the black rocks and the white furred rabbits would be able to hide in the white rocks, but the gray furred rabbits would stand out in both of the habitats and thus would not survive. Disruptive Selection is believed to be the driving force behind sympatric speciation.

Disruptive selection is of particular significance in the history of evolutionary study, as it is involved in one of evolution's "cardinal cases", namely the finch populations observed by Darwin in the Galápagos.

He observed that the species of chav finches were similar enough to ostensibly have been descended from a single species. However, they exhibited disruptive variation in beak size. This variation appeared to be adaptively related to the seed size available on the respective islands (big beaks for big seeds, small beaks for small seeds). Medium beaks had difficulty retrieving small seeds and were also not tough enough for the bigger seeds, and were hence maladaptive.
What is evolution?
Strictly speaking, biological evolution is the process of change over time in the heritable characteristics, or traits, of a population of organisms. Heritable traits are encoded by the genetic material of an organism (usually DNA). Evolution generally results from three processes: random mutation to genetic material, random genetic drift, and non-random natural selection within populations and species.
What is a Fossil?
Fossils (from Latin fossus, literally "having been dug up") are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa (phylogeny) are some of the most important functions of the science of paleontology.
Founder Effect
The founder effect was defined by Ernst Mayr in 1963 to be the effect of establishing a new population by a small number of individuals, carrying only a small fraction of the original population's genetic variation. As a result, the new population may be distinctively different, both genetically and phenotypically, from the parent population from which it is derived. In extreme cases the founder effect is thought to lead to the speciation and subsequent evolution of new species. The founder effect is a feature that can also occur in memetic evolution.

In the figure shown, the original population has nearly equal numbers of blue and red individuals. The three smaller founder populations show that one or the other color may predominate (founder effect), due to random sampling of the original population. A population bottleneck can also cause a founder effect even though it isn't strictly a new population.

In addition to founder effects, the new population is often very small and shows random genetic drift, and an increase in inbreeding due to small population size. Furthermore, the new population is often characterized by low genetic variation, due to the population bottleneck. This can be observed in the limited gene pool of Easter Islanders and those native to Pitcairn Island.
Gene Flow
In population genetics, gene flow (also known as gene migration) is the transfer of alleles of genes from one population to another.

Migration into or out of a population may be responsible for a marked change in allele frequencies (the number of individual members carrying a particular variant of a gene). Immigration may result in the addition of new genetic material to the established gene pool of a particular species or population, and conversely emigration may result in the removal of genetic material.

There are a number of factors that affect the rate of gene flow between different populations. One of the most significant factors is mobility, and animals tend to be more mobile than plants. Greater mobility of an individual tends to give it greater migratory potential.

Maintained gene flow between two populations can also lead to a combination of the two gene pools, reducing the genetic variation between the two groups. It is for this reason that gene flow strongly acts against speciation, by recombining the gene pools of the groups, and thus, repairing the developing differences in genetic variation that would have lead to full speciation and creation of daughter species.
Who is Wallace?
Alfred Russel Wallace, OM, FRS (January 8, 1823 – November 7, 1913) was a British naturalist, explorer, geographer, anthropologist and biologist. He did extensive field work first in the Amazon River basin, and then in the Malay Archipelago, where he identified the Wallace line dividing the fauna of Australia from that of Asia.

He is best known for independently proposing a theory of natural selection which prompted Charles Darwin to publish his own more developed and researched theory sooner than he had intended. He was also one of the leading evolutionary thinkers of the 19th century who made a number of other contributions to the development of evolutionary theory, including the concept of warning colouration in animals. Wallace was also considered the 19th century’s leading expert on the geographical distribution of animal species and is sometimes called the "father of biogeography".
Vestigial Organ
Vestigial structures are anatomical structures of organisms in a species, which have lost much or all of their original function through evolution. They are typically in a degenerate, atrophied, or rudimentary condition. They are often called vestigial organs, although not all of them are actually organs.
Transitional Form
A transitional fossil or transitional form is the fossilized remains of a life form that illustrates an evolutionary transition. It can be identified by having certain primitive (plesiomorphic) traits in comparison with its more derived relatives, such as defined in the study of cladistics. "The Missing Link" is a popular term used for transitional forms.
Natural Selection
Natural selection is the evolutionary process by which favorable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavorable traits that are heritable become less common. Natural selection acts on the phenotype, or the observable characteristics of an organism, such that individuals with favorable phenotypes are more likely to survive and reproduce than those with less favorable phenotypes. If these phenotypes have a genetic basis, then the genotype associated with the favorable phenotype will increase in frequency in the next generation. Over time, this process can result in adaptations that specialize organisms for particular ecological niches and may eventually result in the emergence of new species.
Temporal Isolation
Populations may mate or flower at different seasons or different times of day. Three tropical orchid species of the genus Dendrobium each flower for a single day; the flowers open at dawn and wither by nightfall. Flowering occurs in response to certain meteorological stimuli, such as a sudden storm on a hot day. The same stimulus acts on all three species, but the lapse between the stimulus and flowering is 8 days in one species, 9 in another, and 10 or 11 in the third. Interspecific fertilization is impossible because, at the time the flowers of one species open, those of the other species have already withered or have not yet matured.
Stabilizing Selection
Stabilizing selection, also known as purifying selection or negative selection, is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. Put another way, extreme values of the character are selected against. This is probably the most common mechanism of action for natural selection.

A classic example of this is human birth weight. Babies of low weight lose heat more quickly and get ill from infectious disease more easily, whereas babies of large body weight are more difficult to deliver through the pelvis. Interestingly, it has been demonstrated that the optimum birth weight (i.e. that which gives highest probability of survival) has shifted upwards as the Caesarian section has become readily available.

Stabilizing selection operates most of the time in most populations. This type of selection acts to prevent divergence of form and function. In this way, the anatomy of some organisms, such as sharks and ferns, has remained largely unchanged for millions of years.

Stabilizing selection can sometimes be detected by measuring the fitness of the range of different phenotypes by various direct measures, but it can also be detected by a variety of tests of molecular sequence data, such as Ka/Ks ratios, changes in allele frequency distributions and the McDonald Kreitman test.
Speciation is the evolutionary process by which new biological species arise. There are four modes of natural speciation, based on the extent to which speciating populations are geographically isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry or laboratory experiments. Observed examples of each kind of speciation[1] are provided throughout.
Sedimentary Rock
Sedimentary rocks are laid down in layers called beds or strata. Each new layer is laid down horizontally over older ones in a process called superposition.There are usually some gaps in the sequence called unconformities. These represent periods in which no new sediments were being laid down, or when earlier sedimentary layers were raised above sea level and eroded away.

Sedimentary rocks contain important information about the history of the Earth. They contain fossils, the preserved remains of ancient plants and animals. The composition of sediments provides us with clues as to the original rock. Differences between successive layers indicate changes to the environment which have occurred over time. Sedimentary rocks can contain fossils because, unlike most igneous and metamorphic rocks, they form at temperatures and pressures that do not destroy fossil remnants.
Reproductive Isolation
An important concept in evolutionary biology, reproductive isolation is a category of mechanisms that prevent two or more populations from exchanging genes. The separation of the gene pools of populations, under some conditions, can lead to the genesis of distinct species. Reproductive isolation can occur either by preventing fertilization, or by the creation of a degenerate or sterile hybrid, such as the case with the common mule and the hinny.
Punctuated Equilibrium
Punctuated equilibrium (or punctuated equilibria) is a theory in evolutionary biology which states that most sexually reproducing species will show little to no evolutionary change throughout their history. When evolution does occur, it happens sporadically (by splitting) and occurs relatively quickly compared to the species' full duration on earth.

For this reason, the theory is sometimes called "evolution by jerks". (Ghiselin, 1986) Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism ("evolution by creeps"), which hypothesizes that most evolution occurs uniformly and by the steady and gradual transformation of whole lineages (anagenesis).
Who is Hutton & Lyell?
Helped scientists recognize that the earth is many millions of years old.
Macro Evolution
Macroevolution refers to evolution that occurs at or above the level of species, in contrast with microevolution[attribution needed], which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. The process of speciation may fall within the purview of either, depending on the forces thought to drive it. Paleontology, evolutionary developmental biology, and comparative genomics contribute most of the evidence for the patterns and processes that can be classified as macroevolution. An example of macroevolution is the appearance of feathers during the evolution of birds from one group of dinosaurs.
Population dynamics. 1798.

Thomas Robert Malthus, FRS (February 13, 1766 – December 23, 1834), usually known as Thomas Malthus, although he preferred to be known as "Robert Malthus", was an English demographer and political economist. He is best known for his highly influential views on population growth.
Population dynamics
Micro Evolution
Microevolution is the occurrence of small-scale changes in allele frequencies in a population, over a few generations, also known as change at or below the species level.

These changes may be due to several processes: mutation, natural selection, gene flow, genetic drift and nonrandom mating.

Mutations provide the raw material which other organisms of microevolution use. Mutation is the rarest potential cause of evolutionary change.

Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance.

Microevolution can be contrasted with macroevolution; which is the occurrence of large-scale changes in gene frequencies, in a population, over a geological time period (i.e. consisting of lots of microevolution). The difference is largely one of approach. Microevolution is reductionist, but macroevolution is holistic. Each approach offers different insights into the evolution process.
In biology, mutations are changes to the base pair sequence of genetic material (either DNA or RNA). Mutations can be caused by copying errors in the genetic material during cell division and by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can occur deliberately under cellular control during processes such as meiosis or hypermutation. In multicellular organisms, mutations can be subdivided into germline mutations, which can be passed on to descendants, and somatic mutations. The somatic mutations cannot be transmitted to descendants in animals. Plants sometimes can transmit somatic mutations to their descendants asexually or sexually (in case when flower buds develop in somatically mutated part of plant).

Mutations create variation in the gene pool, and the less favorable (or deleterious) mutations are removed from the gene pool by natural selection, while more favorable (beneficial or advantageous) ones tend to accumulate, resulting in evolutionary change. For example, a butterfly may develop offspring with a new mutation caused say by ultraviolet light from the sun. In most cases, this mutation is not good, since obviously there was no 'purpose' for such change at the molecular level. However, sometimes a mutation may change, say, the butterfly's color, making it harder for predators to see it; this is an advantage and the chances of this butterfly surviving and producing its own offspring are a little better, and over time the number of butterflies with this mutation may form a large percentage of the species. Neutral mutations are defined as mutations whose effects do not influence the fitness of either the species or the individuals who make up the species. These can accumulate over time due to genetic drift. The overwhelming majority of mutations have no significant effect, since DNA repair is able to mend most changes before they become permanent mutations, and many organisms have mechanisms for eliminating otherwise permanently mutated somatic cells.
Why is Macro Evolution controversial?
Macroevolution is controversial in two ways:

It is disputed among biologists whether there are macroevolutionary processes that are not described by strictly gradual phenotypic change, of the type studied by classical population genetics. Within the Modern Synthesis school of thought, microevolution is thought to be the only mode of evolution (i.e. what is sometimes thought of as "macroevolution" actually consists of the compounded effects of microevolution - the only difference between them is one of time and scale).
A misunderstanding about this biological controversy has allowed the concept of macroevolution to be coopted by creationists. They use this controversy as a supposed "hole" in the evidence for deep-time evolution.
Give an example of a Vestigial Organ
What year did Charles Darwin publish the Origen of Species?
Who was Lamarck?
Evolution (1809) theory of acquired characteristics.

Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. Over time this process led to change in species
Who was Malthus?
Population dynamics (1798)

Reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.
Population dynamics
What's aritificial selection?
Nature provides the variation among different organisms, and humans select those variations that they find useful.
True or false
Does natural selection result in changes in inheritied characteristics of a population?
Darwin argued that living things have been evolving on Earth for millions of years. Any proof?
Fossil record, the geographic distribution of living species, homologous structures of living organisms, and similarities in early development.
How many sources of genetic ariation are there? Name them.
Two. Mutations and the genetic shuffling that results from sexual reproduction.
What is the number of phenotypes that a given trait depends on?
Depends on how many genes control the trait.
True or False.
2 phenotypes determine a given trait?
False. Depends on how many genes control the trait.
True or False.
Natural selection on single-gene traints can lead to changes in allele frequency.
Can changes in allele frequency lead to evolution?
Name the three ways that natural selection can affect the distributions of phenotypes.
1. Directional selection
2. Stabilizing selection
3. Distributive selection
What are the five conditions required to maintain genetic equilibrium from generation to generation?
1. Random mating
2. large population
3. no movement into or out of the population
4. no mutations
5. no natural selection
True or false.
As new species evolve, populations become reproductively isolated from each other.
How did speciation in the Galapagos finches occur?
1. Founding a new population,
2. geographic isolation, changes in the new populations gene pool,
3. reproductive isolation, 4. and ecological competition.
Genetic Equilibrium
In theory, genetic equilibrium is a state in which a population is not evolving.

[edit] Assumptions For Genetic Equilibrium
No gene mutations
Large population size
Isolated population (away from other populations of the same species)
Gene of interest has no effect on survival or reproduction
Mating is random
Rarely, if ever, do all five conditions prevail at the same time in nature. Gene mutation is infrequent but inevitable. Three processes may drive a population away from genetic equilibrium--natural selection, gene flow, and genetic drift.

Deer and mice have high amounts of genetic equilibrium.

When a population has reached genetic equilibrium, that means that the species will stop evolving and will stay in its present form.

Compare to: Hardy-Weinberg equilibrium
Gene Pool
The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction.
What other name is Genetic Equilibrium know as?
the Hardy-Weinberg law
What does the Hardy-Weinberg law state?
It states that genotypes, the genetic constitution of individual organisms, exist in certain frequencies that are a simple function of the allelic frequencies—namely, the square expansion of the sum of the allelic frequencies.
What three processes can drive a population away from genetic equilibrium?
1. natural selection,
2. gene flow,
3. and genetic drift.
Gradualism is the belief that changes occur, or ought to occur, slowly in the form of gradual steps
Homologous Organs
Vestigal organs
Lamarkian Theory
Lamarckism or Lamarckian evolution is a theory put forward by the French biologist Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck, based on heritability of acquired characteristics, the once widely accepted idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring.
Who proposed the Lamarkian Theory?
Jean-Baptiste Lamarck.
Who is Mendel?
Published work on inheritance in the 1860s. It was not recognized as important until after 1900.
Did Darwin know genentics?
Did Darwin understand how inherited traits were passed from generation to generation?
No. He did not understand genetics.
True or False.
When scientists determine whether a population is evolving, they may look at the sum of the populations alleles.
What is the sum of a populations alleles known as?
Gene pool.
True or False
Darwin' work was about how life changes over time?
Salamanders need a moist environment to survive?
From the following which word is the subspecies?
Ensatina eschscholtzii croceater?
In E.e. croceater (15; brown), what does the 15 represent? What does the brown represent?
15 is the total number of individuals. Brown is the
In E.e. croceater (15; brown) 32/R, what does the 32/R represent?
Where one or more specimens were collected.
Is the current consensus that the genus Ensatina (salamander) that it is comprised of one polytypic species or 7.
1 species with 7 subspecies.
Sometimes the salamander is referred to as a ring species. What does it mean by ring species.
Ring species refers to a species whose subspecies form a ring around the Great Central Valley of California.
Describe the salamanders preferred habitat.
In the North forest clearings and wooded areas. In the south north-facing slopes of canyons, oak woodland, mixed grassland Also - close to streams and ponds where the soil is moist.
What was the name of the ship that Darwin sailed on?
HMS Beagle 1831.
What year did Darwin sail?
1831 on the HMS Beagle.
In Darwin's On the Origin of Species by Means of Natural Selection, what were the main points?
1. Organisms produce more individuals than can survive.
2. No two individuals are exactly the same.
3. The best adapted survives.
4. Survivors reproduce and pass traits on to future generations.
5. Descent with modification.
What role do fossils play in supporting the evolution theory?
Transitional forms and migration paths / timing.
Give an example of a homologoous organ.
From Thiel's notes: Birds wing. Other's include whales pelves, moles eyes.
What is the amount of dna shared between an human and a chimp?
What can you think of when thinking of Artificial Selection?
Charpaez dog
What can you think of when thinking of Geographic Distribution?
Deer family.
Explain Embryological Similarities.
Similarities exist between fish, salamanders, turtles, chickens, rabbits, and humans as the embryo develops.
Punctuated Equilibrium
Punctuated equilibrium (or punctuated equilibria) is a theory in evolutionary biology which states that most sexually reproducing species will show little to no evolutionary change throughout their history. When evolution does occur, it happens sporadically (by splitting) and occurs relatively quickly compared to the species' full duration on earth.

For this reason, the theory is sometimes called "evolution by jerks". (Ghiselin, 1986) Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism ("evolution by creeps"), which hypothesizes that most evolution occurs uniformly and by the steady and gradual transformation of whole lineages (anagenesis).
How might an evolutionary biologist determine if a species is evolving?
From slide 7 of Thiel's notes.
What is Industrial Melinism?
A classic case demonstrating natural selection is referred to as industrial melanism. A change occurred in a number of moth species populations in the late 1800’s in industrialized areas of England and the United States. Prior to this period, moth populations were primarily composed of light colored mottled moths with occasional mutant dark colored (melanic) moths. During this period, over a number of generations, the populations changed such that the majority of moths were dark colored. This could be explained by a change in the bark of trees in the woods surrounding the industrial areas. The bark had gone from being whitish in color to a soot-covered black. Moths rest on bark during the day. Light colored moths were now conspicuous to birds whereas dark moths were not. Dark colored moths therefore had higher fitness and left more offspring for the next generation.
Bottleneck Effect
Population size dramaticaly reduced by:
1. Natural disaster
2. Disease
3. Excessive hunting

Leaving a small surviving population wiht gene frequencies nothing like the ancestral population.
Founder effect
A small number of individuals leave the population and establishes a new population in another area. The new population has allele frequencies much different than the ancestral population.
Gene flow
Genes move into or leave a population as a result of a migration.
Mutation / Natural Recomgination & Natural Selection
Formation of new genetic code or combinations of genetic code can lead to natural selecting forces cuasing a significan change in allelic frequencies.
Go over salamander map.
Ask questions.
Describe human evolution and migration.
See Thiel's chart.
What percentage of DNA is identical in humans.
How often do mutations in mitochondrial dna and the Y chromosome happen?
Once every 1,000 to 10,000 years.
In the case of a mutation in the mitochondrial dna and the Y chromosome, will all offspring carry the same mutation?
Yes. Example is 3 million men descendents from Irish.
What is homo floresiensis?
3 foot tall men around 18,000 years ago. Nicknamed Hobbits. Brain roughly 1/3 our size.
Selecting foreces can have one of three effects on phenotypes in a population.
1. Disruptive selection
2. Stabilizing selection
3. Directional selection
Changes in frequencies extended over a great deal of time may lead to the development of a new species.
Can an expanding population moving into environments that have a different combination of selecting forces lead to a new species?
Yes. Page 15 of Thiel's notes.
What is Geographic Isolation?
Isolation evident in islands promotes significant speciation.
Does isolation enhance speciation?
Yes. Page 16 of Thiel's slides.
Can a mountain range, a canyon, a river, or a freeway cause Geographic isolation?
Yes. Think Grand Canyon.
Describe Behavioral Isolation.
Examples are courtship rituals, nesting preferences, territoriality. This can prevent two genetically compatable species from breeding allowing additional change to take place over time.
Preserved remains of ancient organisms.
True of False

The shape of a tortoises shell cound determine which island it lived on.
True. Page 371.
How did tortoises and birds differ among the islands of teh Galapagos?
Shell shapes, beaks. Why?
True or false.
Most people in Darwin's time believed that the Earth and all life had existing for a couple of thousand years?
True. (page 373). They also thought that nothing had changed.
James Hutton
1795. Proposed that the Earth had to be much older than thought.

He proposed layers of rock form very slowly. Some rocks are moved up. Others are buried. Some pushed from sea floor to form mountains.
Wrote Priciples of Geology. Earth millions of years old. Same process exist today.
Did Darwin write his before or after the Boston Tea Party?
Boston Tea Party 1773. Darwin sets sail 1831. 1859 publishes On the Origin of Species.
Who wrote Essay on the Principle of Population?
Thomas Malthus. (1798) The human population will grow faser than the space and food needeed to sustain it.
Who is Alfred Wallace?
Writes to Darwin speculating on evolution by natural selection. (1858)
Did Darwin publish his Origin of Species before or after the United States Civil War?
Before (1859 vs. 1861).
Who used a crab with a bigger right claw as an example of passing characteristics to offspring?
Lamarck (1809). This was later found to be incorrect. He proposed that selective use or disuse of organs would cause someone to lose certain traits. These traits could be passed on to offspring.
Are strips on Zebras an example of natural variation in a species?
Yes. (page 378)
Natural variation
Differences amoung individuals of a species. Found in all types of organisms.
Artificial selection
Humans selected the variations that they found useful.

Darwin observed English farmers and breeders. Biggest hogs, fastest horses, etc.
Natural Selection =
Survival of the fittest.
Natural Selection
Results in changes in teh inherited characteristics of a population. This changes increase a species' fitness.
Decent with Modifications
Darwin proposed that over long periods of time, natural selection produces organisms that have different structures, establish different niches, or occupy different habitats. Each living species has decended from other species. This implies that all living organisms are related to one another.
The principle of common descent.
All species living and dead were derived from common ancestors.
Geographic Distribution of living species.
Main point is that derived from different ancestors.
Homologous body structures.
Similarity of body parts of animals with backbones.
Are homologous structures evidence of evolution?
Yes. (Page 384)
Relative frequency
The number of times that allele occures in a gene pool compared with the number of times other alleles occure. Often expressed as percents.
Can sexual reproduction change the relative frequency of alleles in a population.
No. Page 395.
Name an example in humans of a single gene trait.
Widow's peak.