Evolution Power Point Notes Name: _________________________Per: ____

How Did Life Begin?When Earth formed, about 4.5 billion years ago, it was a fiery ball of molten rock. Eventually, the planet’s surface cooled and formed a rocky crust. Water vapor in the atmosphere condensed to form oceans. Most scientists think life first evolved in these oceans and that evolution occurred over hundreds of millions years.

Earth’s early atmosphere contained little or no oxygen. It was composed of:- Carbon dioxide - Carbon monoxide - Ammonia- Nitrogen gas - Hydrogen gas - Methane- Hydrogen-containing water vapor

The Mysteries of Life’s Origins?Miller-Urey Model of the origin of life was proposed by chemists Miller and Urey in 1953

They tested the hypothesis that ___________________________ could have been produced for early life on Earth

They put gases that they proposed had existed on Earth into a device and simulated _____________ by providing electrical sparks. After a few days, they found a collection of organic molecules which included some of the

essential building blocks of life: - 21 AA - FA - other hydrocarbons (molecules made up of hydrogen and carbon) These results supported the hypothesis that the basic chemicals of life could be _________________________________________________ _____on primitive Earth and under conditions like those simulated in the experiment.

Evolution Part 1: Natural Selection Charles Darwin (1809 – 1882)

The Father of Evolution Born in 1809 in England Sailed on the HMS Beagle During his voyage, he made observations that led him to his ___________________________________ - a

scientific explanation for the diversity of life, by proposing how modern organism evolved from common ancestors.

5 year unpaid voyage lasted from 1831 to 1836Many of Darwin’s conclusions were based on observations of wildlife in the Many of Darwin’s conclusions were based on observations of wildlife in the __________________________________________________________The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean, directly on the equator. Among other things, Darwin noticed The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean, directly on the equator. Among other things, Darwin noticed there were several types of finches on these islands. there were several types of finches on these islands. In particular, Darwin observed something odd about the finches: they all looked like a bird he had seen on the South American continent.

The most distinct difference among finch species is their The most distinct difference among finch species is their ___________ ___________ which are adapted for the specific diets available on the islands. which are adapted for the specific diets available on the islands. DarwinDarwin hypothesized that some of the birds from South America migrated to the Galapagos. hypothesized that some of the birds from South America migrated to the Galapagos. Once on the islands, the birds must have Once on the islands, the birds must have ______________ over the years. This would explain the numerous species of birds present.______________ over the years. This would explain the numerous species of birds present.

Phylogenetic Tree:A diagram showing the _______________________________________ of a species of an animalHow many major branches does this tree represent? ______

Certhidea olivacea& C. Fusca

Geospiza difficilis

Warbler Finch

Tree Finch

Ground Finch

G. conirostris

G. scandensCactus Finch

(nectar, seeds, blood)

G. agnirostris

Seed-eating Finch

G. fuliginosa G. fortis

Platyspiza crassitrostris

C. heliobates

Cactospiza pallida

Woodpecker-like Finch

Vegetarian Finch

Insect-eating Finch

Camarhynchus pauper

C. sittacula

C. pauper

(seeds & insects)

“Original” Finch

Species Vary Over Time

In addition to observing living species, Darwin also collected _____________ - preserved remains of ancient organisms.Darwin noticed that these fossils included many extinct animals that were similar to, yet different from living species

After returning from the Galapagos and studying all the different types of plants & animals he collected during the voyage, Darwin After returning from the Galapagos and studying all the different types of plants & animals he collected during the voyage, Darwin concluded that organisms change over time…concluded that organisms change over time…Darwin called this… Darwin called this… __________________________________________________ which means which means change in species over timechange in species over timeDarwin called the mechanism for evolution Darwin called the mechanism for evolution _________________________ __ _________________________ __ a.k.a.a.k.a.________________________________________________________. Those . Those individuals that are better fit for their environment have a greater chance to individuals that are better fit for their environment have a greater chance to __________ __________ and mate to __________________ and provide and mate to __________________ and provide offspring. Therefore, the genetic traits of these individuals become more common or offspring. Therefore, the genetic traits of these individuals become more common or ____________________________over time. The genetic traits of less fit individuals become less common or over time. The genetic traits of less fit individuals become less common or frequent over time.frequent over time.

In Darwin’s time, most scientists believed that each species remained unchanged in the form that it was originally created. In Darwin’s time, most scientists believed that each species remained unchanged in the form that it was originally created. Scientists then started to try to find explanations for the origins of fossils…….. Scientists then started to try to find explanations for the origins of fossils…….. In 1809, the French Scientist named Jean ___________________ proposed a hypothesis for how organisms In 1809, the French Scientist named Jean ___________________ proposed a hypothesis for how organisms change over generations. He believed that over the lifetime of an organism, change over generations. He believed that over the lifetime of an organism, ______________________________________________would would ____________________________________________________________________because of either the use or disuse of the feature. because of either the use or disuse of the feature. According to According to Lamarck, these changes would then be Lamarck, these changes would then be ________________ ________________ on to offspringon to offspring, enabling species to change over time, enabling species to change over time

Lamarck had correctly identified that a change is a species is linked to an organism’s Lamarck had correctly identified that a change is a species is linked to an organism’s __________________________________________________________________________________

The key that unlocked Darwin’s thinking about how evolution occurs was an essay written in 1798 by an English economist named The key that unlocked Darwin’s thinking about how evolution occurs was an essay written in 1798 by an English economist named Thomas ___________________. Malthus wrote that if the human population grew unchecked, there wouldn’t be enough living space Thomas ___________________. Malthus wrote that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone. Malthus said that the forces that controlled population growth included: war, disease, natural disasters and and food for everyone. Malthus said that the forces that controlled population growth included: war, disease, natural disasters and famine.famine.

The common ancestor is at the bottom

When Darwin read Malthus’ work he realized that it applied to all organisms as all organisms have the potential to produce more offspring than can possibly survive. If all the descendents of any species survived for several generations, they would overrun the limited natural resources on Earth.

This doesn’t happen as most offspring die before reaching maturity and only a few survivors reproduce. Why was this important? Darwin was convinced that all species _________________ but he needed a scientific explanation. So Darwin began to ask questions:Which individuals survive? And why?

Recipe for Natural SelectionRecipe for Natural Selection

1.____________________________________________________________Every species is different even within itself.Example: some beetles (of the same species) are green and some are brown

2. ____________________________________________________________There is a constant struggle for survival. Examples are: Natural disasters like drought, fire, flood, etc.

Competition for resources like food, space, or mates Other dangers like predation, disease, or parasitism

3. _______________________________________________________________________________________Fit – better adapted; more likely to surviveExample: The surviving brown beetles have brown baby beetles because this trait has a genetic basis.

4. __________________________________________________________________________Conversely, over time, genes for less favored characteristics (green colored beetles) will become less common, but not eliminated (because they’re preserved in the heterozygotes)Example: Brown coloration allows the beetle to have more offspring and becomes more common in the population. If this process continues, eventually almost all individuals in the population will be brown.

How Natural Selection Works1. Natural Selection on Single Gene Traits2. Natural Selection on Polygenetic Traits

When a new pesticide is introduced, it will usually kill most insects. Just by chance, some individuals in the insect population carry genetic variation that allows them to resist that pesticide. Pesticide resistance is an adaption that enables individuals to survive and reproduce to pass these resistant alleles to their offspring. So, over time, the frequency of resistant alleles will increase in the population.

1. Natural Selection on Single Gene TraitsNatural Selection on single gene traits can produce changes in ____________________________ that may result in simple changes in the _______________________________.Example: A population of brown lizards undergoes mutations in a gene that determines body color. The mutation produces black and red lizards.

- Red lizards will be more visible to predators so they will be less likely to survive and reproduce to pass on the red allele- Black lizards will be able to absorb more sunlight and warm up faster on cold days. A high body temperature allows

these black lizards to move faster to avoid predators. The black coloration acts as an adaptation to increase _______________so that the allele for black coloration and the black phenotype will increase in _______________in the lizard population.

2. Natural Selection on Polygenetic TraitsNatural Selection on polygenetic traits can affect the phenotype and produce 3 types of selection:

(a) Directional selection(b) Stabilizing selection(c) Disruptive selection

(a) __________________________________ - when individuals at ______________of the curve have ___________________than individuals in the middle or at the other end. The range of phenotypes will shift towards those individuals with the higher __________________________Example: Only large seeds are available for a food source. Birds with big thick beaks will be able to feed more easily than birds with small beaks. The big beak adaptation produces greater fitness and this will eventually lead to greater reproductive success. Over time, the average beak size of the population will increase.

(b) ___________________________________________ - when individuals near the ____________of the curve have higher fitness than individuals at either end. The center of the curve remains at its current position, but the overall curve becomes more _________________.Example: Very small and underweight wild baby animals are less likely to survive. Extremely large baby animals are more likely to experience difficulty being born. The fitness of the smaller

Example:Green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do.

Directional selection

Stabilizing selection

or larger babies is less than that of the average size baby animal. As a result, birth weight is under the influence of stabilizing selection.

(c) _______________________________________ - when phenotypes at the _________ or ____________lower ends of the curve have higher fitness than individuals near the middle.

Example: A bird population lives in an area wherethe medium sized seeds become less common. Birds with either small or large beaks would eventually have higher fitness.

Summary of Darwin’s Contributions: provided evidence that species evolved In 1859, he proposed the ________________________________________to explain evolution. (Survival of the fittest).

Natural selection depends on an individual’s ability to reproduce and leave offspring. Over time, _______________ within a population leads to the _____________________of old species by new species better

able to adapt to the environment. Some evidence from ______________ supports the theory that species on Earth have evolved from ancestral forms that

are__________________.

Common Ancestry Darwin proposed that living species are descended, with changes over time, from common ancestors – an idea called

________________________________________ _________________________________________________ - all species whether living or extinct, are united by descent from

ancient _____________________________ and show ________________ due to _______________________________ and _________________.

Evolution Part 2: Speciation and Hardy-Weinberg PrincipleWhat is a species?

A species is one or more populations of individuals that can __________________, producing ______________ offspring._______________________ _______________________ is the process by which new species are formed over time. is the process by which new species are formed over time.

How Does Speciation Occur?How Does Speciation Occur?______________________________________________________is when populations of individuals are geographicallyis when populations of individuals are geographically separated which prevents separated which prevents ____________ ____________ with one another. This is calledwith one another. This is called ____________________________. Eventually they will no longer share a common gene pool. ____________________________. Eventually they will no longer share a common gene pool. FFor example, this can be due to the formation of new mountains, canyons, rivers, oror example, this can be due to the formation of new mountains, canyons, rivers, or otherother landforms.landforms.

Over time, ___________________________, due to random mutations that result in adaptationsOver time, ___________________________, due to random mutations that result in adaptations that improve an individual’s ability to reproduce and survive, makes the DNA so different that the populations are no longer able tothat improve an individual’s ability to reproduce and survive, makes the DNA so different that the populations are no longer able to ________________________________________ (mate) with each other. Their chromosomes may not even match up. Once there is no gene flow between the (mate) with each other. Their chromosomes may not even match up. Once there is no gene flow between the populations, mutations start to accumulate differently in each population and the populations populations, mutations start to accumulate differently in each population and the populations _______________ ________________ _ into ______________ into ______________ ________________________. This is called . This is called ____________________________________________________- change on a grand scale leading to - change on a grand scale leading to ___________________ ___________________ and and _______________________._______________________.

Sometimes population ranges of different species overlap, but they still won’t interbreed. Here are some reasons whySometimes population ranges of different species overlap, but they still won’t interbreed. Here are some reasons why ::

Physical incompatibilityPhysical incompatibilityFor obvious reasons, crickets can’t mate with giraffes, for example. They just don’t have a common enough ancestor.For obvious reasons, crickets can’t mate with giraffes, for example. They just don’t have a common enough ancestor.Different mating schedules or locationsDifferent mating schedules or locationsFor example, certain flowers and insects may prefer to mate at different times of day, may bloom at different times of the year, or may For example, certain flowers and insects may prefer to mate at different times of day, may bloom at different times of the year, or may prefer different mating locations. So even if they are not geographically separated, they still won’t mate with someone with a different prefer different mating locations. So even if they are not geographically separated, they still won’t mate with someone with a different schedule.schedule.BehaviorBehaviorAnimals, especially, are picky. Some have elaborate mating rituals or specific traits they look for in a mate. For example, in some Animals, especially, are picky. Some have elaborate mating rituals or specific traits they look for in a mate. For example, in some spiders and mantises, if the rituals aren’t pleasing to the female, she will eat the male.spiders and mantises, if the rituals aren’t pleasing to the female, she will eat the male.

What causes change in a population?Natural selection acts onNatural selection acts on____________________________________; Evolution (the change) is measured in; Evolution (the change) is measured in______________________________________. Individuals don’t . Individuals don’t evolve; they can grow and develop, but they don’t evolve. evolve; they can grow and develop, but they don’t evolve.

Disruptive selection

___________________________ ___________________________ is defined as the change in (gene) allele frequencies in a population over many generations.is defined as the change in (gene) allele frequencies in a population over many generations.

Hardy-Weinberg PrincipleHardy-Weinberg Principle

In 1908, 2 scientists independently came up with a mathematical way to measure if a population is evolving by measuring changes in In 1908, 2 scientists independently came up with a mathematical way to measure if a population is evolving by measuring changes in allele frequenciesallele frequenciesThe Hardy-Weinberg Principle makes predictions for allele frequencies (like Punnett squares) for ____________________ and NOT The Hardy-Weinberg Principle makes predictions for allele frequencies (like Punnett squares) for ____________________ and NOT individuals. Here’s how it works:individuals. Here’s how it works:

Suppose that there are 2 alleles for a gene – Suppose that there are 2 alleles for a gene – AA (dominant) and (dominant) and aa (recessive). A cross of these alleles can produce 3 possible (recessive). A cross of these alleles can produce 3 possible genotypes: __________________________genotypes: __________________________

The frequencies of genotypes in the population can be The frequencies of genotypes in the population can be predicted by the following equation where predicted by the following equation where p p and and q q are are frequencies of the dominant and recessive allelesfrequencies of the dominant and recessive alleles ..

Suppose in one generation, the frequency of the Suppose in one generation, the frequency of the AA allele is allele is 40% (p = 0.40) and the frequency of the 40% (p = 0.40) and the frequency of the aa allele is 60% (q = allele is 60% (q = 0.60). If this population is in genetic equilibrium, chances of an0.60). If this population is in genetic equilibrium, chances of an individual in the next generation having genotype individual in the next generation having genotype AAAA would be would be 16% (p2 = 0.16 or 16%). The probability of the genotype 16% (p2 = 0.16 or 16%). The probability of the genotype aa aa would be 36% (q2 = 0.36). The probability of genotype would be 36% (q2 = 0.36). The probability of genotype Aa Aa would be 48% (2pq = 0.48)would be 48% (2pq = 0.48)If a population doesn’t show these predicted phenotype If a population doesn’t show these predicted phenotype frequencies, evolution frequencies, evolution IS TAKING PLACEIS TAKING PLACE

What causes genetic change in a population?What causes genetic change in a population?4 main factors that cause change of allele frequencies in a population are:4 main factors that cause change of allele frequencies in a population are:

•• ____________________________________________________________ •• ____________________________________________________________ •• ____________________________________________________________ •• ____________________________________________________________

Natural selection – already discussed; adapts a population to its environmentNatural selection – already discussed; adapts a population to its environment Genetic drift is the Genetic drift is the ___________________________________________________________________________________. ___________________________________________________________________________________. InIn

small populations, individuals that carry a certain allele may have more offspring than other individuals. Over a series of small populations, individuals that carry a certain allele may have more offspring than other individuals. Over a series of random occurrences can cause an allele to become more or less common in a population. Two examples of random occurrences can cause an allele to become more or less common in a population. Two examples of GENETIC GENETIC DRIFT: DRIFT:

oo ____________________________________________________________________ – occurs when the size of a population is drastically reduced in size due to– occurs when the size of a population is drastically reduced in size due to a natural disaster. The gene pool of the surviving population may now have allele frequencies that differ from those a natural disaster. The gene pool of the surviving population may now have allele frequencies that differ from those of the original gene pool. [Many alleles are lost completely while others may be over or under represented from what of the original gene pool. [Many alleles are lost completely while others may be over or under represented from what they were in the original population.] Ex: cheetah population is at risk due to a severe reduction of genetic diversitythey were in the original population.] Ex: cheetah population is at risk due to a severe reduction of genetic diversity

oo ____________________________________________________________________ – allele frequencies change as a result of migration of a small subgroup of– allele frequencies change as a result of migration of a small subgroup of a population. These founding individuals may carry alleles that differ in frequencies from those of the parent gene. a population. These founding individuals may carry alleles that differ in frequencies from those of the parent gene. Ex: insects blown from the mainland to an island; humans moving from one continent to another Ex: insects blown from the mainland to an island; humans moving from one continent to another

Gene flow Gene flow – another word for gene flow i– another word for gene flow is_________________s_________________ __ . . WithWith gene flow thegene flow the _______________________ _______________________of a of a population ispopulation is _____________ _____________by individuals moving into (or out of) a population.by individuals moving into (or out of) a population.

Mutation – Mutation – as we have studied in past units, _______________________________________. This is the other factor that as we have studied in past units, _______________________________________. This is the other factor that can change allele frequencies. can change allele frequencies.

Can you inherit all mutations? Can you inherit all mutations? They must occur in the gametes to be passed on to offspringThey must occur in the gametes to be passed on to offspring

Evolution Part 3: Evidence of EvolutionScientific Evidence of Evolution includes:

1. _____________________________ 2. _____________________________ 3. _____________________________

FOSSIL RECORD In order for fossils to form:

Calcium must be ____________________ by harder minerals Burial must occur by ______________________deposited in

swamps, mud, ocean floors, tar pits, areas near volcanoes that spew out volcanic ash, etc. Body of the organism must_________________________. For ex., an animal with a hard

exoskeleton (crab) would have a better chance of becoming fossilized than a soft-bodied organism (worm)

What happens if the organism doesn’t die in sediment? Fossil doesn’t form; decomposition takes What happens if the organism doesn’t die in sediment? Fossil doesn’t form; decomposition takes place. Fossils are how we know that extinct animals used to live here on Earth. place. Fossils are how we know that extinct animals used to live here on Earth.

(frequency of (frequency of AAAA) + (frequency of ) + (frequency of aaaa) = 100 and (frequency of ) = 100 and (frequency of AA) + (frequency of ) + (frequency of aa) = 100 ) = 100

Hardy-Weinberg Principle predicts that five conditions can disturb genetic equilibrium and cause ______________ to occur:1. _________________________________________________________2. _________________________________________________________3. _________________________________________________________4. _________________________________________________________5. _________________________________________________________

One or more of these conditions usually occurs for populations. This means that most of the time in populations, _________________________

EquusEquus – the Modern Horse – the Modern Horse evolved from the dog-sized Hyracotherium. Notice it evolved from a four-toed front foot to the one-toed front foot of the modern horse.____________________says that this happened gradually over millions of years. The evolution of the horse is an example of gradualism. Evidence for gradualism is found in ________________________

What else changed over time according to the diagram (and the fossil record)? Size of the teeth increased. Why? Earth was changing and becoming dryer; grasses were evolving and becoming the primary food source, requiring greater grinding surface. Height increased as being able to see predators over the grass was an advantage. Running on one toe increased the number of joints and therefore, the speed of the animal to run from predators.A hoof instead of a soft pad on the foot provided protection from hard ground and coarse grass

_________________________says that species existed in long periods of stasis (same) interrupted by brief periods of genetic instability that produced changes. This This overall change still happened over millions of years. Evidence for this theory is observed in the ____________________________.

BIOGEOGRAPHYIs the study of the Is the study of the ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________This is what first suggested evolution to Darwin. Species tend to be more __This is what first suggested evolution to Darwin. Species tend to be more __ _____________ _________________________________ ____________________ to other species from the same area than to other species with the sameto other species from the same area than to other species with the same way of life but living in different areas. way of life but living in different areas.

HOMOLOGIES Characteristics that are shared by related species because they have been inherited in some way from a _______________________________

There are 3 main categories of homologies:1. ____________________ – includes:

(a) homologous structures (anatomical homologies)(b) analogous structures(anatomical analogies)(c) vestigial structures

2. ________________________ 3. _________________________

1. (a) Anatomical – Homologous StructuresError: Reference source not found

Anatomical homologies arise from _________________ evolution (adaptive radiation). They come from the same embryological structures._________________________: formation of new species from an existing species adapting to new environments.Homologies are evident.Divergent Evolution Example: All canines have long legs, walk on their toes, have bushy tails, non-retractable claws and a dew claw on the front feet. These and other shared characteristics are due to the fact that they all come from a _________________________. Different populations diverged at different points and created all these species. Sometimes it is called ___________________________

(b) Anatomical – Analogous StructuresThese are structures present in two different organisms that have the _________________________ but are ______________ ___________________ and have _____________________________. For example, the wing of a mosquito and the wing of a bird are both used for flying but these structures are made up of different materials (chitin vs. bone) and originate from different evolutionary pathways.

Homologous structures have the same____________________________, but may have evolved ____________________________________.

For example, the bones on the front fins of a whale are homologous to the bones in a human arm and both are homologous to the bones in a bat wing and cat leg.

All homologous structures have evolved from a common ancestral structure but now these structures are used to do different tasks for each organism

Anatomical analogies often result from________________________; organisms evolve similar features independently, often because they live in similar habitats. These similarities are NOT due to having a common ancestor. Sometimes called _________________________.______________________________: the process by which unrelated species become similar as they adapt to similar environments. Convergent evolution example: Sharks, dolphins, tuna, penguins have streamlined bodies, and fins. These similarities are NOT because they have a common ancestor. Sharks are cartilaginous fish, dolphins are mammals, tuna are bony fish, and penguins are birds. They share similarities because they both adapted to the same _____________________________________ and are all ____________________

(c) Vestigal StructuresVestigial structures are structures that ____________________________________________ and/or are much _______ _______________________than they used to be.

Examples include: whale pelvisappendixgoose bumps tailbonepinky toeshuman canineswisdom teethmuscles to move human earshind limbs on a whalenipples on human males

2. Biochemical Homologies: comparing Genes to show relationshipsIdea is that _____________________________________ ___________________________________ and therefore ______________________________ in common proteins than distantly related organisms. . For example, fish, chimpanzees, and humans all have hemoglobin (protein carrying oxygen in the blood). You would expect the human hemoglobin to be more similar to chimpanzee hemoglobin than to fish hemoglobin since the chimp and the human are more closely related.

3. Developmental Homologies_____________________________________________________________________________________________________________________________________________________________________________________________Similar patterns of embryological development provide further evidence that

Organisms have descended from a common ancestor.

Why are these vestigial structures retained? The presence of the structure doesn’t affect an organism’s survival so natural selection doesn’t act to eliminate it.