PCB 4674: EVOLUTION EXAM 1

All living organisms on Earth are related through

Common Ancestry

Five-year voyage around the world. This ship sailed from England, around the tip of South America, to the Galápagos Islands, around the southern coast of Australia and Africa, and back to England. During this journey, Darwin collected thousands of samples: plants, animals, fossils, and rocks. He made careful and important observations about the organisms he encountered.

HMS Beagle

Darwin surmised that birds with certain physical features, those that allowed them to eat certain foods in their environment, survived and reproduced. Through reproduction, they could pass on these physical features to their offspring, thus increasing the frequency of these features in the overall population of birds. In different environments, different physical features would be favored and would be "selected."

Natural Selection

Driver of evolution called natural selection. Darwin refereed to it as

Descent With Modification

The 13 different finch species that currently live on the Galápagos is a kind of rapid and prolific speciation known as an _______ _______. An evolutionary pattern in which many species evolve from a single ancestral species.

Adaptive Radiation

Common scientific views before Darwin

The earth is young, species divinely created, and species are unchangable

Emerging scientific views before Darwin

The earth is old, the earth's surface, plants, and anaimals havechanged over time

Study of Earth

Geology

Study of Fossils

Palentology

Study of classification and relationships of organisms

Taxonomy & Systematics

Study of populations

Demography

Study of organisms and their changes over time

Evolutionary biology

How old is the earth

4.6 Billion Years

Scottish geologist who lived in the 18th century and who recognized that wind and rain caused erosion and formed sand, small rocks, and soil. Discovered the strata and uniformitarianism.

James Hutton

Particles could then be redeposited and form the layered pattern of rock we call

Strata

Hutton's ideas of geological strata and time depth rely on the assumption that the processes that occur today are the same ones that have occurred in the past. This is known as ____________, an idea that is widely accepted in all scientific fields today.

Uniformitarianism

Hutton's ideas were soon tested by the great geologist _______ ______ , who confirmed that it would take millions, not thousands, of years for Earth's geological strata to form. Who lived in the late 18th, early 19th centuries.

Charles Lyell

He invented the microscope and examined fossil wood under his new device. He noted that the cellular structure of the fossil wood was the same as the wood that exists today. He lived in the 17th century.

Robert Hooke

He proposed that fossils were from organisms that no longer existed. He also discovered that different fossils could be found in different geological strata. He also proposed that different layers of strata represent groups of organisms that had been wiped out in a series of catastrophic events. He lived in the 18th/19th century.

Georges Cuvier

Cuvier proposed evolution happened catastrophically, others proposed it happened slowly and gradually. Although many lineage extinctions are not dramatic, there is growing evidence that there have been ______ _______ events.

Mass Extinction

One mass extinction event happened 65 million years ago; it marks the end of the dinosaurs and the beginning of the reign of ______.

Mammals

In 1991, researchers discovered a massive crater, partially underwater, on the ________ _____________ in modern-day Mexico. It has been dated to about 65 million years and preserves a high concentration of iridium, an element that is exceptionally rare on Earth but common in meteors and comets. A comet or meteor, roughly 6 miles wide, struck Earth 65 million years ago, with the force of 100 million megatons. To put this in perspective, the current arsenal of nuclear weapons stockpiled by the United States military is 1,400 megatons. This means we would need to set off our entire nuclear arsenal 70,000 times in a row to equal the force of this impact. This was a catastrophic event; it is remarkable that anything survived.

Yucatán Peninsula

Prior to Cuvier's work on fossils, the great Swedish naturalist ________ ________ devised a system for naming and classifying all living organisms. His system is still used today, and allows scientists from all over the world, speaking different languages, to understand one another. Lived in 18th century. He proposed that each species should receive a unique name composed of a genus and a species.

Carolus Linnaeus

Genus/Species of Humans, Chimpanzees, Boa constrictor, and Gorilla:

Homo sapiens, Pan troglodytes, Boa constrictor, Gorilla, gorilla

Linnaeus also devised a ___________ __________ scheme in which all living organisms could be placed within a kingdom, phylum, class, order, family, genus, and, finally, species. The Linnaean system of classification reveals that living organisms, including humans, are clustered in distinct ways- ways that could only be explained if these living organisms shared a common ancestor.

Hierarchical Classification

Humans are the only living species in the genus

Homo

We are members of the family ________ and the superfamily hominoidea. However, we are not alone in this superfamily. Chimpanzees, gorillas, orangutans, and gibbons are also in the superfamily hominoidea. They are in this superfamily because they share features with us like large brains, mobile shoulders, and an upright posture. These other animals reside in our superfamily because we share a common ancestor with them.

Hominidae

Thomas Malthus, an economist, wrote An Essay on the __________ ___ _________, a book that laid the foundation for many of Darwin's ideas. Malthus observed that humans often have more than two offspring. If parents (two people) continued to have more than two children, then the population of humans would grow. In fact, Malthus argued that the growth could be exponential, resulting in billions and billions of humans in a short period of time.

Principle of Population

Malthus stated that populations are limited by their resources. Therefore, there is a _________ ___ ______, with only certain individuals surviving and reproducing. Notice how this observation by Malthus, combined with Darwin's recognition that there is considerable variation in a population, forms the basis for natural selection.

Struggle For Existence

The idea that living organisms have changed over time was already around by the time Darwin came along. Most notably, the French scientist ________ ____________ _________ argued that plants and animals had changed over time, or evolved. He proposed the mechanism of evolution known as "Inheritance of Acquired Characteristics" his mechanism was wrong!

Jean-Baptiste Lamarck

Giraffes once had a short-necked ancestor. In order to reach higher and higher branches, giraffes stretch their necks. Adult giraffes who have stretched out their necks will pass on this acquired feature of a long neck to their offspring. Over time, necks get longer and longer in the giraffe lineage.

Larmack's Mechanism of Inheritance of Acquired Characteristics

What Darwin contributed to science was not just the evidence that life on Earth had evolved. He proposed a mechanism for how this can happen: ______ ________

Natural Selection

There is variation in an ancient giraffe population, with some individuals having longer necks than others. They all feed on high branches. Those with longer necks eat, survive, reproduce, and pass on the trait of a long neck to the next generation. Those with shorter necks cannot reach as much food, are weak, and may even starve to death. The frequency of long-necked individuals in the population increases over time.

Darwin's Mechanism of Natural Selection

Lyell & Hutton's contributions to Darwin's realizations

Earth is old, Gradualism

Cuvier's contributions to Darwin's realizations

Fossils resemble living forms

Malthus' contrubitions to Darwin's realizations

Ideas about reproduction, populations, and variation

Linnaeus & Lamarck's contrubitions to Darwin's realizations

Species related and can change

After his voyage on the Beagle, Darwin spent the next several decades on an intellectual voyage. Unlike his first trip, this one took place almost entirely in one place: the study in his home, Down House, in Kent, England (shown on the left). There, Darwin did many experiments, collected vast amounts of evidence, and eventually organized his thoughts into a book, __ ___ ______ __ ________. In this book, Darwin proposed natural selection as the mechanism for evolution.

On the Origin of Species

Darwin's 2 realizations from reading the work of other scientists and creating his own conclusions

1) All life on Earth is related through common ancestry. More-related organisms share a more recent common ancestor.

2) The mechanism for evolutionary change is natural selection. All he had to do now was publish these ideas.

In 1858, Charles Darwin received a startling letter from the naturalist Alfred Russel Wallace. Like Darwin, Wallace made wonderful observations about the natural world and wondered why living organisms looked as they did. Also like Darwin, Wallace made many of his observations on islands—in Wallace's case the Indonesian archipelago. Wallace collected many samples, read the works of Lyell and Cuvier, and thought deeply about the mechanism of evolutionary change. In 1858, Wallace wrote to Darwin and proposed a mechanism for evolution that was strikingly similar to Darwin's own ideas. They agreed to jointly present their findings to the Linnaean Society of London in July 1858. However, it is Darwin who went on to write On the Origin of Species, which presented the details of natural selection and the evidence for evolution, the following year (the handwritten title page is shown at the bottom right). The fact that two scientists, working independently and on opposite sides of the world, both came up with the same mechanism for evolution is robust evidence that natural selection is a powerful tool for explaining the pattern of life.

Charles Darwin & Russel Wallace

Natural selection can only operate if there is ________. This is the fundamental tenet of natural selection. If every member of a species is the same size, or the same color, or has the same sized beaks, then how can certain individuals survive over others?

Variation

During Darwin's time, it was thought that offspring were a 50-50 blend of their parents. This idea, known as _______ ________, was quite a problem for natural selection because it would dilute favorable adaptations, limiting the power of selection to cause evolutionary change.

Blended Inheritance

Gregor Mendel's _____ ______ experiments laid the foundation for modern genetics. Mendel bred over 28,000 ^^ and very carefully mapped how traits like flower color and position, pea color and shape, and plant height passed from generation to generation.

Pea Plant

Mendel discovered that traits were inherited discretely, through units ultimately called ________.

Genes

Genes come in different versions, called _____.

Alleles

Often one version of allele could exert ________ over another version that would be called recessive. The two versions, one from the mother and one from the father, did not blend.

Dominance

Cross-Breeding Experiment Model is called a

Punnett square

Mendel breeds a tall pea plant with a short one. According to the ideas of blending inheritance, all of the offspring should be intermediate in height. But that is not what Mendel found. Imagine that the tall plant has two versions of the tall allele, which we'll call BIG T. The small plant has two versions of the small allele, which we'll call little t. When these plants reproduce, one allele is passed on from the maternal line and another from the paternal line. This would result in all possible offspring having the same combination of alleles: one BIG T and one little t. But instead of these being plants of intermediate height, Mendel found all these plants to be tall. The allele BIG T is dominant over the little t. Now let's breed these plants together and examine all of the different combinations of alleles in the offspring. One will have a BIG T from the mother plant and a BIG T from the father plant. Two plants will have a mixture of alleles: one BIG T and one little T. And one plant will have two little t alleles. Mendel bred thousands of plants and found that the ratio was always 25% two dominant BIG alleles, 50% mixed alleles, and 25% two little recessive alleles. But Mendel could not see the alleles themselves; all he could see was their effect on the organism. What he saw was that three out of every four plants (75%) were tall, and 25% were small. There was no in-between. Tall—which we call the phenotype—had the allele combination of either TT (two BIG T's) or Tt (one BIG T and one little t), which we call the genotype. The small ones could only have the genotype tt (two little t's), because little t is recessive. We'll go into this more in a later chapter, but the point here is that Mendel's work showed how inheritance works. Unfortunately, Mendel's work went unnoticed until after his death, when three botanists independently rediscovered Mendel's work and replicated his findings.

Dominant/Recessive Genes

Mendel's work on inheritance provides an understanding of how variation arises and is passed from generation to generation. Darwin's work provides an understanding of how that variation leads to differential survival and reproduction. Together, these two big ideas of inheritance and natural selection can be combined into an _______ ________. An understanding of both genetics and evolutionary processes.

Evolutionary synthesis

This question led to the field of population genetics.

How do the total sum of genetics vary within and cross populations?

Thomas Hunt Morgan worked with fruit flies and was particularly interested in their ___________.

Chromosomes

Morgan discovered that a gene could change spontaneously—something called a _______. This could lead to a new variant, like the different eye colors, or the four-winged fly. If beneficial, this could spread to future generations, making this an important cause of evolutionary change.

Mutation

In addition to natural selection and mutation, two other processes can cause a change in a population over time (in other words, evolution). These processes are called

Gene Flow and Genetic Drift

Spread of genes from one gene pool to another; it is also known as admixture. This process can introduce variants into a population that were previously either quite rare or absent altogether. For instance, the gene that causes sickle-cell anemia is more common in people from the western part of Africa (~10% have the gene) than in people from northern Europe (~0% have it). In the last few hundred years, the United States has been populated by people from both parts of the world, and these populations have had children. The sickle-cell gene has flowed between populations, resulting in about 5% of African Americans and white Americans having the sickle-cell gene.

Gene Flow

Occurs when populations are quite small and gene frequencies change because of a random drifting effect. For example, there are two populations of fish: a small (sparsely populated) one and a large one. The small population happens to have a single red fish along with five gold fish. The larger population has a more even mixture of the different fish, with about one-third of the total colored red. Imagine that, just by chance, the two populations of fish lose a red individual. The large population will change very little, going from a frequency of 33.3% to 32.8%. However, the smaller population has a dramatic change in the gene pool, going from a 16.6% red representation to zero. The only way to get a red fish back into that population would be through mutation and subsequent selection or gene flow from the larger pool. If these two populations become separated from each other, they may very well evolve into different fish species: one with a red variant, the other without.

Genetic Drift

_____ are discrete units packaged on things called chromosomes, which reside in the nucleus of your cells. They are simply codes for making proteins.

Genes

Chromosomes are made in part of ___________. Which all of life contains.

Deoxribonucleic Acid (DNA)

In 1953, the British scientists _______ ________ and Francis Crick, using detailed microscopic images taken by Rosalind Franklin, discovered the structure of DNA, and it is the structure that helps reveal how DNA works.

James Watson

The father of modern taxonomy

Carolus Linnaeus

The belief God created everything including evolution

Special Creation

These two geologists put up the concept that the earth is very old

Hutton and Lyell

A principle that states that geologic change occurs suddenly

Catastrophism

Founder of vertebrate paleontology

Cuvier

This hypothesis is that species change over time as they interact with their rneivonrment

Lamarck

Lamarck's hypothesis was based on (and was wrong)

Use and disuse and inheritance of acquired characteristics

Organisms have descended from a common ancestor and have accumulated adaptations to their environment over time

Darwin's theory of Descent with Modification

Members of a population often vary in their inherited traits and that all species can produce more offspring than their environment can support

Darwin's observations

The smallest unit in nature that can evolve

Population

Individuals whose inherited traits give them a higher probability of surviving and that this unequal ability of individuals to survive and reproduce lead to accumulation of favorable traits.term-29

Darwin's inferences

What are the five evidences of evolution

Fossil record, homologous/vestigial structures, patterns of development, biogeography, and biochemistry

A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

Species

All of the alleles in all the individuals that make up a population

Gene Pool

A change in the relative frequencies of alleles

Microevolution

Frequency is Measured on on this scale

0.00 - 1.00

What are the five Hardy-Weinberg Equilibrium criteria requirements?

Large Population, Isolated Population, No Net Changes from Mutations, Random Mating, No Natural Selection

Hardy-Weinberg Equation

p² + 2pq + q² = 1.00

What are the causes of Microevolution?

Genetic Drift, Gene Flow, Mutations, Non-Random Mating, and Natural Selection

The only adaptive cause of microevolution

Natural Selection

Genetic Drift is a ___ population

Small

Chance events cause allele frequencies to change in small populations

Genetic Drift

Small individuals colonize a new area

Founder Effect

Population size is drastically reduced and diversity is decreased

Bottleneck Effect

Migration of individuals between populations

Gene Flow

Mutation equates to the origin of

All new alleles

Individuals are not equal in reproductive success (fitness)

Natural Selection

Natural selection operates on

Genetic Variation

The three types of variation within populations are

Quantitative characters, discrete characters, and polymorphism

Measurable characteristic (i.e. height)

Quantitative Characters

Exact characteristic (i.e. attached/unattached)

Discrete Characters

A population in which 2 or more forms of a discrete character (morphs) are present

Polymorphic Population

A graded change in a character along a geographic axis

Cline

Heterozygotes "protect" deleterious recessive alleles

Diploidy

Natural selection favors diversity (i.e. sickle cell)

Balancing Selection

This type of balancing selection is when ONE sickle cell anemia allele protects you from malaria, but having both alleles will give you sickle cell.

Heterozygote Advantage

This type of balancing selection is when fish learn to avoid a parasitic type of fish, the parasitic fish evolves with the hosts behavior.

Frequency Dependent Selection

Name the three types of natural selection

Stabilizing Selection, Disruptive Selection, and Directional Selection

Intermediates are favored in this type of natural selection

Stabilizing Selection

One extreme is favored over another in this type of natural selection

Directional Selection

Extremes are favored in this type of natural selection

Disruptive Selection

Changes in chromosome number leads to reproductively isolated plants

Polyploidy