Game

If you got lost on an island who would you rather be stuck on the island with?

The island is completely remote and you will be the only two on the island.

Goal is to survive!

Left or Right? Bear Grylls

Left or Right?

Left or Right?

Left or Right?

Your mom or dad?

If you are on fire, what do you do?

Is this evolution?

EvolutionChapter 14

What do you think about when you hear the word evolution?

Evolution:

All the changes that have been transformed life over an immense time. Or gradual change over time.

Adaptation:

Inherited characteristic that improves an organism’s ability to survive and reproduce in an environment.

Story

In 1831, a young man at 22 years old volunteered to set sail on a voyage to visit different countries.

The ship was meant to charter the South American coastline for the British navy.

This man did not want to fight or be in the navy.

He wanted to observe nature.

Who am I talking about?

Charles Darwin

14.1 Darwin developed a theory of evolution

There were two theories about life before Darwin.

1. Species were all fixed, or permanent. (Creationism)

2. The Earth is only 10,000 years old and still not changing.

Which do you agree with, are they correct?

True or False

Kangaroos powerful hind legs were the result of ancestors strengthening their legs by jumping and then passing the acquired leg strength to their offspring.

False

Giraffes physically stretched their necks to be able to reach tall trees for food.

False

In the 1700s, French naturalist Georges Buffon came up with the idea that Earth is much older than a few thousand years.

In the 1800s, Jean Baptiste Lamarck proposed that life evolves.

He thought that by using certain body parts, organisms develop certain characteristics, and these characteristics would be passed to offspring.

Darwin’s voyage

English naturalists

In 1831-1836 traveled to South America from England on the HMS Beagle.

Big stop was the Galapagos islands.

Founding father for evolution.

5 year voyage

Darwin’s observations

Large # of species

Organisms are well adapted to their environments

Organisms do not necessarily appear in same ecosystems / locations

Collected fossils

Galapagos Islands Each island had different climate and vegetation Observed different but similar species on the different

islands EX: tortoises, finches, marine iguanas

Giant Tortoises of the Galapagos

Pinta Island

Hood Island

Isabela Island

Darwin’s Finches

Depending on the location, Darwin noticed variations in tortoises and finches.

Some tortoises had long necks (eat tall shrubs) while other had short necks ( eat food off the ground).

Some finches had long beaks ( eat bugs), while others had short beaks (eat nuts).

Ideas from geology

Geologist Charles Lyell proposed that geological processes such as erosion could explain the physical features of todays Earth.

Darwin learned that the slow process of mountains suggested that the Earth is very old.

These slow and gradual changes occurred over long periods of time.

Erosion

In 1844 after doing further research and support from other scientists, Darwin wrote a 200 page essay that outlined his ideas, but did not release it to public.

After gathering more research in 1859 he released his book The Origin of Species.

Why did Darwin wait so long to release his book?

Didn’t want to slander his fathers name, going against the church.

Darwin’s two main points 1.

Believed that organisms today descended from ancestral species.

Descent with modification:

Early organisms spread out into different environments and over millions of years the organisms changed or adapted.

Hare- two different environments

The jackrabbit with dark fur blends in to the desert, while the jackrabbit with light fur blends in to the snow.

Darwin’s two main points 2

Natural selection:

Process by which individuals with inherited characteristics well-suited for its environment will leave more offspring.

14.2 Evolution has left much evidence

What are some evidence for evolution?

Fossil Record

Geographic Distribution

Similarities in Structure

Similarities in Development

Molecular Biology

Fossils

Fossils:

Preserved remains or markings left by organisms that lived in the past.

Fossil record:

Chronological collection of life’s remains in the rock layers, recorded during the passage of time.

Extinct:

Species no longer exists

Paleontologist found fossils from 3.8 billion years ago!

FOSSIL RECORD

Transitional Forms

Common Ancestor

Modern Whale

Geographic distribution

Some species now living on different continents may have descended from common ancestors.

Geographic Distribution Spotted Owl

Similarities in Structure

Homologous structures:

Similar structures in species sharing a common ancestor, but with different function.

Analogous structures:

Different structure but similar function.

Vestigial structure:

Remnants of important structures from ancestral species, but serve no current function.

Similarities in Development

Many embryos of vertebrates look very similar during certain stages of development.

Which is more closely related?

Molecular Biology

DNA/Protein in closely related species are more similar.

Humans /chimps – Only 1 amino acid difference (Closely related)

Humans /dogs – 11 amino acid differences

Humans /rattlesnakes – Approx. 20 amino acid differences (Distant relatives)

14.3 Darwin proposed natural selection as the mechanism of evolution

Population:

Group of individuals of the same species.

Suppose we take a single species and colonized them on different islands.

What will happen over time?

Each organism will change depending on the environment.

Darwin’s Finches

Darwin asked how did these different beaks arise?

His idea…

Darwin’s Idea of Natural Selection

All species tend to produce excessive numbers of offspring, called overproduction.

As we produce more offspring, resources become limited.

This leads to a struggle of existence.

The best adapted organisms will survive and reproduce. This is called survival of the fittest.

What makes organisms different is called variation.

Variation:

Differences among members of the same species.

Natural Selection Giraffes

Natural Selection College

Artificial selection:

Selective breeding of domesticated plants and animals to produce offspring with genetic traits that humans value.

Ex.

Farmers want plants to produce more grain.

People have been dog breeding certain types of dogs.

Nova and Luna

Natural selection in action

What do you spray on your grass to kill insects?

Pesticides

With the first spray of pesticide on your yard you can kill 99% of the insects.

If you use that same pesticide are you going to kill the same amount the next time you spray?

Most likely not.

Why?

The insects who resisted the first spray now reproduced with more offspring that are resistant to the pesticide.

14.4 Microevolution is a change in a population’s gene pool

Gene pool:

Consists of all alleles (alternative forms of genes) in all the individuals that make up a population.

Changes in gene pools

Microevolution:

Evolution on the smallest scale.

Frequency of alleles:

How often certain alleles occur in a gene pool. Generation to generation change in frequencies of alleles.

Hardy-Weinberg equilibrium:

Condition that occurs when the frequency of alleles in a particular gene pool remain constant over time.

Changes in gene pools

Remember alleles are letters. Depending on these letters certain traits will be expressed.

Applying the Hardy-Weinberg

Equilibrium allows us to see if the

alleles in a population are changing.

Genetic Drift

Genetic drift:

A change in gene pool of a population due to chance.

All populations are subject to genetic drift.

The smaller the population is, the more impact of genetic drift has on the population.

When you flip a coin 10 times how many heads would you expect?

5

But if you flipped a coin 10 times and heads came up 7 times, would that be reasonable?

Probably

What if you flipped a coin 1000 times and heads came up 700 times? Would that be reasonable?

Probably not.

As sample size increases, the likely percentage should level out, ie heads 50% and tails 50%.

Within a small population you are more likely to see genetic drift.

Bottleneck effect

Disasters such as earthquakes, floods, droughts, and fires may drastically reduce the size of a population and lower the genetic variation. Reducing the size of a population, also reduces the size of its gene pool.

Just because some organisms are better suited for the environment does not mean that can survive a natural disaster. Due to chance.

Bottleneck Effect

Founder Effect

When a few individuals colonize an isolated island, the smaller the colony the less its genetic makeup will represent the gene pool of the larger population from which the colonists came. Due to chance.

Gene flow and mutation

Gene flow:

The exchange of genes with another population.

Occurs when fertile individuals or their sex cells migrate between populations.

Gene flow example

Suppose only white flowers live in a field.

Wind takes the pollen of the white flowers

and lands on a population of red flowers.

Now the genes of each flower

are being mixed.

Mutation

Recall a mutation is a change in an organisms DNA.

Albinism can happen in many species.

When can albinism be helpful in an environment?

If it snows the organism can

blend in.

What could happen to the

population of the albino organism?

Review

Genetic drift, gene flow, and mutations can cause microevolution or change in allele frequencies but it is by chance that these changes would be adaptations.

Fitness:

Contribution that an individual makes to the gene pool of he next generation compared to the contributions of other individuals.

If you are the biggest, strongest animal in your specie, are you always going to be fit?

Remember even if the biggest, strongest, lion in the jungle has zero fitness if it is sterile.

A return to the Galapagos

What is happening with this picture regarding finches beak length and passing of time?

Depending on the season, when it’s wet season food is plentiful for all finches, but when it’s dry season the finches with long beaks are more prevalent.

14.5 Evolutionary biology is important in health science

In some African populations, sickle cell disease affects 1 out of 25 individuals.

Sickle cell is a disease of the abnormal shape of red blood cells which weakens the body, causes pain, and damage to organs.

Caused by a recessive allele, so if your genotype is aa you have sickle cell, if your genotype is Aa you do not have sickle cell, but you are a carrier.

If you are a carrier Aa, you are immune to malaria.

Areas in Africa where malaria is common, the benefits outweigh the risks of having sickle cell allele in a population.

Example.

In some places 4% of the population is homozygous for sickle cell, however 32% of the population is heterozygous and protected from malaria.

Evolution of antibiotic resistance in bacteria

What does the word antibiotic mean?

Anti= opposite bio= life

Antibiotic= killing life.

Antibiotic:

Medicines that kill or slow the growth of bacteria.

When you take an antibiotic, some bacteria stays alive and becomes immune. Those bacteria will reproduce and now resistant to the original antibiotic.

Example

Tuberculosis.

Doctors now do not want to

prescribe antibiotic because

bacteria is becoming resistant.

What are some abiotic things that have gone extinct? Why?