Evolution

How old is the Earth?

3.6-4.2 billion years old. Consisted of CH4 (menthane), H2O (water), NH3 (ammonia), CO (carbon monoxide), SO2 (sulfur dioxide). RNA gave rise to life on Earth.

If the species' DNA differs by 6 base pairs, how much time has passed since they had a common ancestor?

75 million years.

What are allele frequencies?

A number of times an allele appears in a population/how common it is.

How fast can evolution occur?

Evolution occurs both within a species and across the species barrier (macroevolution = speciation??) Evolution via speciation may occur by one of two alternative models: - Gradualism - Punctuated equilibrium

What is a single-gene trait?

A trait controlled by a single-gene. Recessive alleles. Examples: widow's peak, ear lobes, hitchhiker's thumb

What is sexual selection? Sexual dismorphism?

A type of *natural selection* arising through preference by one sex for certain characteristics in individuals of the other sex. Individuals with certain traits are more likely than other individuals to obtain mates. males and females can be different Distinction in appearance. Often manifested in a size difference, but it can also include forms of adornment. Examples: Manes on lions or colorful plumage on birds.

How fast can punctuated equilibrium occur?

According to this, species remain stable for long periods before undergoing abrupt and rapid change (speciation). Speciation is a periodic process (big changes occur suddenly, followed by long periods of no change) This view is supported by the lack of transitional fossils for most species.

What are the proper sequence of events that occurred in this video that exemplifies evolution?

Environment changed, mutation, coloration, predation.

What is macroevolution?

Major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time.

Which effect can greatly reduce the population size and genetic variation?

Both bottleneck and founder effect.

How did domesticating cows (raising them for food) support the evolution of lactase persistence?

Cows were a source of food for humans and became a selecting factor for humans who had the gene for lactase persistence.

If a person does not produce the enzyme lactase, and they drink milk products that contain the sugar lactose, they get sick. What happens to the lactose sugar in a person that does not produce the enzyme lactase?

Bacteria digest the lactose, causing diarrhea, gas and bloating.

What is punctuated equilibrium?

Based on the idea that since you cannot see changes in a species, there must be very long periods when no changes occur. This says that evolution occurs in short bursts followed by long periods of equilibrium. This means that species do not evolve gradually and instead really rapidly with long periods of stability and no change in between. Evolution is caused by a change in the environment that necessitates a need for quick change.

What is artificial selection?

Selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

How fast can gradualism occur?

Speciation generally occurs uniformly, via the steady and gradual transformation of whole lineages Speciation is a smooth and continuous process (big changes result from many cumulative small changes) This is supported by the fossil record of the horse.

What is allele frequency?

The number of times the allele occurs in a gene pool compared to the total number of alleles in a gene.

*What is something important about natural selection?*

The primary mechanism for evolution. However, there are other ways that evolution can occur. One way is called Genetic Drift. Both N.S. and G.D. have the same principles of heritable traits and variation within a specific population. But G.D. does not focus on traits that might be the best "fit" for its environment but rather random changes.

What is coevolution?

The process in which two or more species evolve in response to changes in each other

Which equation is which?

p + q = 1 - allele frequencies, GENE POOL p² + 2pq + q² = 1 - phenotype/genotype, describing, INDIVIDUAL

What is the trend that you usually see with polygenic traits?

There is a small amount of short people, a small amount of tall people and most of the people have the average type of height.

Who were Hardy and Weinberg?

They said that if 5 specific conditions exist together then there would be no evolution

What happens when a mammal stops drinking milk?

They stop producing lactase.

How fast can speciation occur?

Can occur abruptly.

Which of the following is a true when describing how geographic separation leads to formation of separate species population?

Change in allele frequency and no gene flow between the population.

True or False: Genetic drift can reduce or eliminate favorable or unfavorable traits from the population.

True.

Why do individuals pick certain mates?

- To have "good genes" so that their kids have "good genes" as well - Looking for mates that they find attractive - Looking for *more an better mates*

What are the types of speciation?

1. Allopatric - The species is separated by a physical barrier (geographic isolation). 2. Sympatric - A species evolves into a new species without a physical barrier (reproductive isolation)

What are the types of prezygotic barriers?

1. Behavioral - differences in courtship displays or mating rituals. When two populations are capable of interbreeding but have differences in courtship rituals or other types of behavior 2. Temporal - two or more species reproduce at different times. Example: three species of orchid all live in the same rain forest. They release pollen on different days, so they can't reproduce together/pollinate with one another 3. Mechanical - differences in anatomy and reproductive organs 4. Gametic - differences in gametes 5. Habitat - lack of opportunity for mates to encounter each other 6. Geographic - differences in habitat or geographical range. Two populations are separated by geographic borders, such as: rivers, mountains, bodies of water. 7. Reproductive - when the members of two populations cannot physiology mate or producing fertile offspring offspring. At that point, they have separate gene pools. Can isolate the gene pools of species and prevent interbreeding

What are the types of sexual selection?

1. Intr*a*sexual selection - when individuals compete with members of the same sex for mates. Usually in the males 2. Int*e*rsexual selection - individuals of one sex (usually females) are choosy in selecting their mates. This is the more common type of selection. Animals try to flatter their desired mates, for example, peacocks spread their feathers

What are the five conditions that a population in Hardy-Weinberg equilibrium must meet?

1. Large population 2. No migrations 3. No mutations 4. Random mating 5. No natural/artificial selection **Rarely are all 5 conditions met in real populations- so alleles and genotype frequencies often do change. The Hardy-Weinberg principle states that the proportions of alleles and genotypes in a population will remain stable as long as this criteria is satisfied.

What are the types of postzygotic barriers?

1. Reduced hybrid viability - short-lived hybrids 2. Reduced hybrid fertility - sterile hybrids 3. Hybrid breakdown - fertile hybrids with sterile offspring STERILE - lacking the ability to reproduce.

What is genetic drift?

A change in allele frequencies caused by random events by *CHANCE.* It is *RANDOM and for a SMALL population.*

What is the bottleneck effect?

A change in allele frequency following a dramatic reduction in the size of a population. After a *major, catastrophic event. The organisms left may not represent the original.*

What is an allele?

An alternate version of a gene

What are the types of genetic drift?

Bottleneck effect and founder effect.

What are alleles?

Different forms of a gene.

True or False: Natural selection acts on individuals, not on populations.

False.

What are mechanisms of evolution based on random chance?

Founder effect, genetic drift, bottleneck effect.

What is a postzygotic barrier?

Happens after the zygote has formed, prevents hybrid from forming into a viable, fertile adult. AFTER ZYGOTE.

Darwin wanted to understand ____ species changed over time.

How

The number of phenotypes produced for a given trait depends upon ________.

How many genes control the trait.

Which summary of the "genes and culture" hypothesis explains why some human populations became lactase persistent?

Humans who did not tolerate milk and suffered terrible consequences did not survive when periods of famine forced them to only rely on milk for a source of food.

Who were James Hutton and Charles Lyell?

Hutton (1785), Lyell (1833) - Hutton and Lyell helped scientists recognize that the Earth is many millions of years old, and the processes that changed Earth in the past are the same processes that operate in the present.

What does the Hardy-Weinberg equation tell us?

If a population is in Hardy-Weinberg equilibrium, allele and genotype frequencies will remain constant, generation after generation. The Hardy-Weinberg principle tells us that something other than the reshuffling processes of sexual reproduction is required to change allele frequencies in a population.

What is an example of genetic variation?

In this island population, some chicks are born with changes to their genes that make them a little different.

How did analysis of body fats in ancient pot fragments support the evolution of lactase persistence?

Milk fats were found, suggesting ancient people drank milk and therefore made lactase.

*What component of evolution is random? What is not random?*

Mutation - genetic drift, natural selection.

Are mutations good or bad?

Mutations are neither good nor bad-- it depends on the environment the organism lives in.

What are the two single-gene traits that phenotypes have?

One dominant and one recessive.

What is natural selection the competition of?

Passing on genes.

What is the change in the color of the mice being driven by?

Predators.

What is a prezygotic barrier?

Prevents the zygote from ever forming through various isolation patterns - biological isolation. BEFORE ZYGOTE.

____________ isolation prevents the fertilization of eggs while ____________ isolation prevents the formation of fertile offspring.

Prezygotic, postzygotic.

What indicates speciation has occurred?

Produce fertile offspring and failure of interbreeding.

*What is evolution mainly caused by?*

Random mutation, gene flow, genetic drift. Can cause microevolution.

Why do humans have a plica semilunaris?

Small piece of tissue that used to be a third eyelid. Some examples of animals with a third eyelid are sharks, alligators, cats, and hawks.

What type of population will genetic drift have a greater impact on?

Small populations.

What is the founder effect?

Some portion of the population leaves to start a new population in a new location or if a population gets divided by a physical barrier of some kind. In this situation, those individuals are *unlikely to be representative of the entire population.* The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors. Based on traits of those who may have left the original population.

What are the types of natural selection?

Stabilizing, directional, disruptive, and (sexual).

What is gradualism?

States that large changes are actually the build up of very small changes over time. They are long and slow changes that occur over thousands of years. The fossil record is evidence of gradualism. Structural adaptations may also be shown in species as they transform into new species. The geologic time scale helps show how species have changed over the different eras since life began on Earth.

What is an example of reproductive advantage?

The bird born with the long bill is able to get more food, survive better, and raise more young.

What is adaptive radiation?

The diversification of a group of organisms into forms filling different ecological niches.

What is speciation?

The formation of new species because of evolution. The unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over the generations.

The fittest individuals survive, reproduce, and pass on their _______.

Traits - Darwin

The higher the UV index value, the higher ________.

UV intensity when the altitude is higher. Scientists could figure out the general skin tone of people from all over the world and look at the UV intensity.

Is genetic drift on small populations a bigger deal? Why?

Yes. This is because some versions of a gene can be lost due to random chance, and this is more likely to occur when populations are small.

What are polygenic traits?

A trait controlled by several genes. Examples: skin color (3 genes), eye color (3 genes), hair color (5 genes), height (many).

What is a selecting agent?

Any factor, environmental or otherwise, that affects fertility or mortality. Examples: available food sources, local predators, and many other factors in or around a biosphere or individual.

How many genes are polygenic traits controlled by?

Two or more, so many different genotypes and phenotypes.

What is disruptive selection?

Favors individuals at both extremes of the phenotypic range so they have a higher fitness. Natural selection works against individuals in the middle.

What is directional selection?

Favors individuals at one end of the phenotypic range and have a higher fitness than the other end. The range of phenotypes will shift as some individuals fail to survive and the other will thrive.

What are the Hardy-Weinberg equations?

p + q = 1 p² + 2pq + q² = 1 p = dominant q = recessive p² = homozygous dominant q² = homozygous recessive 2pq = heterozygous/hybrid

What is a species?

A group of similar organisms that can mate with each other and produce fertile offspring.

What are factors that can lead to evolution?

- Sexual reproduction - Mutations This causes the genetic variation needed to make the process of evolution present.

Who was Jean-Baptiste Lamarck?

(1744-1829) - He was a French naturalist and zoologist who proposed the inheritance of acquired characteristics. Thought that animals improved themselves throughout their life and passed on their beneficial traits to their offspring.

Who was Charles Darwin?

(1809-1882) - An English naturalist that established that all species over time have descended from a common ancestor. This branching pattern of evolution resulted in a process he called *natural selection.*

What happened on Darwin's voyage?

(1831) - On the HMS Beagle, during the 5 year voyage, he collected hundreds of species: flora, fauna, and fossils while studying scientific books and articles. Read some of Lamarck's books and found them to be different from what he thought. Most significant were those from the Galapagos Islands - many species, especially the finches varied from island to island. He believed that because of their isolation they developed adaptations to each different region. He promoted natural selection as the method of evolutionary changes. He wrote a book called "The Origin of Species." Returned to England and tries to make sense of his collection. The different species varied according to island, and this was a clue that lead Darwin to developing the theory of evolution by natural selection. Hypothesized that descendants of a remote ancestor spread into various habitats over millions of years, they accumulated diverse modifications, or *adaptations,* that fit them to specific ways of life in their environment. *Conclusion: Living beings compete over resources, and only the most fit survive* - natural selection. He also read Hutten, Lyell, and Malthus. Helped formulate his theory.

Who were Stanley Miller and Harold Urey?

(1950s) - Stanley Miller and Harold Urey, University of Chicago, conducted 1st experiments to simulate the first step of the theory proposed by Oparin - early Earth could have been created by energy of lightning causing gaseous molecules. Designed to clarify the chemical reactions that occurred in the primitive Earth. Identified organic molecules that are common in all living things: hydrocarbons, some amino acids. "Primordial soup" -wasn't accepted as a theory to explain how life appeared on Earth b/c was no proof or evidence to support the theory. Proved that biological molecules can form in early Earth-like conditions.

What is the peppered moth?

(Biston betularia) - a common moth found in Europe, Asia, and North America. It is commonly found in two forms, or morphs: a dark morph and a light, speckled morph. Birds are a frequent predator of the peppered moth. Example of NATURAL SELECTION.

What is Lamarck's theory?

*Selective use or disuse of organs or traits acquired or lost during an individual's lifetime.* "Species are not constant, they evolved from pre-existing species" 1. Law of use and disuse - the more the organism uses the body part the stronger it becomes 2. Inheritance of acquired characteristics - trait that is developed through use and disuse could be passed onto the offspring

What are the evidences of evolution?

1. Comparative Anatomy/structural evidence- similarities in bone structures (homologous structures). Homologous structures, analogous structures, vestigial structures 2. The Fossil Record - remains of extinct species resemble those that are alive today. Provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time. Darwin argued that living things have been evolving on Earth for millions of years. 3. Geographical Distribution of Living Species - Darwin realized that similar animals in different locations were the product of evolutionary descent 4. Comparative Embryology - different species have similar stages of development. Early staged reveal similarities not visible in adults. All vertebrate embryos have a tail and pharyngeal (throat) pouches 5. Comparative Biochemistry/DNA sequencing - most significant. The less amino acid, protein differences, the more closely related. Shows common ancestry. **Molecular clock - predicts the rate of mutations every 1,000 years

What are the four main factors that influence the natural selection process?

1. Overproduction - to produce more offspring than can possibly survive Q: Why do fish lay thousands of eggs A: Bottom of the food chain, so need to have many so that some survive. Opposite case for humans. 2. Competition Intraspecific - Competition between one species. A = among, the same. Interspecific - Competition between two different species Example: red tail hawk + golden eagle → mouse 3. Variation - any difference between individuals within a species 4. Selection - the environment "selects" organisms with helpful traits to be the parents of the next generation

What are the types of comparative anatomy?

1. Vestigial structures - traits that no longer have any function in modern day organisms and used by ancestors. Examples: tailbone in humans, leg bones in whales), tonsils, male nipples, nictitating, membrane 2. Analogous structures - features of different species that are similar in function but *not necessarily in structure.* No common ancestor, but live in similar environments and have similar adaptations. Examples: bat wing, bird wing, insect wind 3. Homologous structures - similar in position and structure but *not in function.* Why they can't reproduce - they are not homologous to each other. Show individual variations on a common anatomical theme. These are seen in organisms that are closely related. Examples: bird wing, frog forearm, human arm, dolphin flipper

*What is modern evolution?*

A change in allele frequency over time. Darwin's hypothesis: all life-forms are related. Molecular biology provides strong evidence for this claim. All forms of life use the same genetic language of DNA and RNA. RNA triplets are translated into amino acids- is essentially universal.

What is adaption?

A change/trait that helps an organism survive and reproduce. The unequal ability of individuals to survive and reproduce leads to adaptations in a population.

What is a population?

A group of individuals of the same species that live in the same area and interbreed.

How does a molecular clock work?

A molecular clock is something that uses the mutation rate in DNA of an organism. The purpose is to dictate when organisms diverged, (the length of time that two species have been evolving independently and when they diverged from a common ancestor).

Why did the black mouse appear in the population of light mice?

A mutation occurred that resulted in a new version of a gene for fur coloration.

Lactase persistence becoming common in the population is explained by

A mutation that enables lactase to be made had allowed people to drink milk. People with this mutation survived to reproduce and passed on the trait.

What is overpopulation?

A result of individuals reproducing successfully and sometimes seasonal fluctuations.

What is an organisms' fitness?

Ability of an organism to survive, reproduce, and pass on it's traits to it's offspring in a specific environment.

What is gene flow?

Allele frequencies in a population can also change as a result of gene flow, where a population may gain or lose alleles when fertile individuals *migrate* into or out of a population or when gametes (such as plant pollen) are transferred between populations. Introduces new alleles into the population; can result in a change in the genetic makeup of a population. Tends to reduce differences between populations.

Similar structures show that they have a common _______.

Ancestor

What is transformism?

Assumes that there are no extinctions, a species can change sufficiently to become a new one, but a single species cannot evolve into two new ones, and each species has its own unique ancestor.

What happened as a result of the Industrial Revolution?

Before the 19th century in England, the air was very clean. The bark on trees was usually light in color. Abundant lichens growing on tree trunks also lightened their appearance. The 19th century was the time of the Industrial Revolution in England. Most of the new industries used coal for energy, and the air was polluted with black soot. In forests near factories, the soot coated trees and killed lichens. As a result, tree trunks became darker.

Who was Thomas Malthus?

British economist. Essay on the Principle of Population. Malthus predicts that the human population will grow faster than the space and food supplies needed to sustain it. He said that population grew exponentially but food increases arithmetically, resulting in famine.

How often do the base pairs used in this example mutate?

By 2 base pairs every 25 million years.

What is microevolution?

Change over a period of time with a certain species or a small group of organisms.

What is the difference between convergent evolution and divergent evolution?

Convergent Evolution: Species A and B ----> look like each other Analogous Structures Divergent Evolution: Common Ancestor ----> Environment A and B Homologous Structures

How would Darwin and Lamarck explain the existence of giraffe necks?

Darwin - Darwin would think that giraffes would reproduce and eventually mate with a giraffe with a long neck, which would cause animals with long necks. This could be from the fact that they're not able to survive without a long neck because they need to reach their food. Lamarck - According to Lamarck, animals were well adapted to their environment because they improved themselves throughout their lives, so he would think that giraffes would stretch their necks and use the limbs that they want to improve to be able to reach the leaves and then pass on these traits to their offspring.

What is the summary of Darwin's theory?

Fact 1: All species have such a great potential fertility that their population size could increase exponentially if all individuals that are born reproduce successfully. Fact 2: Most populations are normally stable in size except for seasonal fluctuations. Fact 3: Natural resources are limited. Inference 1: Production of more individuals that the environment can support leads to a *struggle for existence* among individuals of a population, with only a fraction of offspring surviving each generation. Fact 4: Individuals of a population vary extensively in their characteristics; no two individuals are exactly alike. Fact 5: Much of this variation is heritable. Inference 2: Survival in the struggle for existence is not random, but depends in part on the hereditary constitution of surviving individuals. Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than less fit individuals - *survival of the fittest* Inference 3: This unequal ability of individuals to survive and reproduce will lead to a *gradual change in population,* with favorable characteristics accumulating over the generations.

What is absolute dating?

Finding out the age of fossils to the year; more precise. Looking at the half-life or radioactive material C-14 ---------> Nitrogen 5,730 years 10g ----> 5g -----> 2.5g 5,730 5,730

What is relative dating?

Finding out the age of fossils within a few thousand years.

What is a gene pool?

Has all copies of every type of allele at every locus in all members of the population. Genetic information found in an organism of many different organisms of that same species.

What are fossils?

Fossils are the preserved traces or remains of organisms that lived thousands or millions of years ago. Any organism that has died and was preserved in some way. Can be found in mud, rock, sand, amber, ice, stone, tar, etc. Fossilized - preserved in stone.

What evidence did Darwin not know?

Genetics, continental drift or the age of the Earth.

What two monosaccharides (simpler sugars) are formed when the lactase enzyme breaks down lactose?

Glucose and galactose.

In order for a DNA sequence to be a good candidate for a molecular clock, what must be true?

Having multiple genes and fossil data would be good candidates for a molecular clock. They will have more constant rates than others. That way they can help narrow down the dates.

What is a heterozygous (hybrid) organism?

Having two different alleles for a given gene.

What is a homozygous (purebred) organism?

Having two identical alleles for a given gene.

Who was Alfred Russel Wallace?

He was the cofounder of "The Theory of Evolution by Natural Selection" and supporter of Charles Darwin. He also came up with the name (The great Aerial Ocean) to describe the atmosphere. (1858) - Darwin gets a letter from A.R. Wallace. Had similar theory for evolution but focused on his research rather than write a book. "The Theory of Evolution by Natural Selection."

What is variation?

Individual characteristics or traits within a specific species. Individuals of a population are different. No two are exactly alike; this variation is heritable.

How does natural selection affect polygenic traits? What are the three types?

It affects the distributions of phenotypes in any of three ways: - Directional selection - Stabilizing selection - Disruptive selection

What is stabalizing selection?

Individuals near the center of the curve have a higher fitness.

How did Darwin think vs. Lamarck think?

Lamarck: Theories of Inheritance An organism changes during its life in order to adapt to its environment. These changes are passed onto its offspring. Darwin: Decent with Modification Populations change as characteristics that allow individuals to survive are selected for. Over long periods of time, natural selection produces organisms that have different structures, establish different niches, or occupy different habitats. Darwin might give an explanation that includes variations in reproduction and in the environment and organisms with traits that suit the environment being the ones to survive. Lamarck may say that changes happen throughout an organism's life.

As the environment changes,...

Natural selection adapts populations to their environment and the species also change and readapt.

How can natural selection on single-gene traits lead to evolution?

Natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution.

________ modifies the population.

Natural selection. These changes increase a species' fitness in its environment.

Was there a difference in the DNA for the lactase gene in "lactase persistent" and "Lactase NON-persistent" people?

No.

How could natural selection lead to evolution?

The advantageous alleles of this variant organism are passed on to offspring. Over many generations, the process of natural selection leads to evolution occurring. It would result in two specific types of species being the only type to exist rather than more than two, and then those species would mate and form new types and would cause evolution. Can also lead to speciation.

What is a phenotype?

The expressed traits of an organism (what we see).

What is a genotype?

The genetic makeup of an organism (what we can't see).

Why do some people have to get their wisdom teeth removed?

The human jaw is a lot smaller than many of our ancestors, so those teeth don't fit.

What is evolution?

The process by which different kinds of living organisms gradually change over time and are thought to have developed and diversified from earlier forms during the history of the earth.

What is natural selection?

The process by which favorable traits tend to increase in frequency over time. It modifies the population. The surviving individuals have similar characteristics and traits, and therefore they mate and create individuals that's inherited characteristics fit them best to their environment. The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.

What is competition?

The struggle for existence is as a result of there being a large population that is too much for what the environment can handle.

According to Lamarck, animals were well adapted to their environment because... According to Lamarck's idea, what would happen if an animal that used their right limbs more often than their left limbs had offspring? True or False: Lamarck thought that animals passed on their beneficial traits to their offspring.

They improved themselves throughout their lives. They would be born with overdeveloped right limbs. True.

What does descent with modification mean?

Traits are inherited by the offspring without being modified during the life of the parent.

Why do human embryos have gill slits?

We are related to fish. Embryos look the same in the beginning but different as they develop.

How are fossils formed?

When plants and animals die and are quickly buried by clay, sand and other sediments.

What is divergent evolution?

When two or more species sharing a common ancestor become more different over time. The accumulation of differences between groups which can lead to the formation of new species.

What is a homozygous recessive (purebred) organism?

When you have two alleles that are the same and they're both recessive.

What does the Hardy-Weinberg test?

Whether a species is evolving. If allele frequencies changing, you know it's evolving The shuffling of alleles that accompanies sexual reproduction does not alter the genetic makeup of the population. No matter how many times alleles are segregated into different gametes, and united in different combinations by fertilization, the frequency of each allele in the gene pool will remain constant unless other factors are operating.