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Life has a history FACTS:

• Extinction is…

• Time lapsed between the extinction of dinosaurs and origin of humans?

• Life has change through time

• Today’s organisms share many features

SCIENTIFIC EXPLANATION:

Descent with modification (evolution)

Independent lines of evidence to support it:

molecular evidence, geographical evidence

fossil evidence, embryonic evidence

Biology professor interviewed in Colbert Report

Misconceptions about Evolution

Evolution is NOT in conflict with any religion

Evolution, as science, looks for natural explanations

to natural phenomena

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Descent with modification within a population

POPULATION is a group of organisms living in an area

That are of of the same species (that can reproduce with each other)

Proportion of the trait in the population has changed over time

But why did this change happen?

1st generation

2nd generation

What has been modified?

the individual?

Mechanism: Mutation

A rare change in the DNA of a gene introducing a new allele

What was the cause for the change in this population?

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What was the cause for the change in this population?

Mechanism: Genetic drift

Changes in the gene pool of a small population due to chance.

Mechanism: Natural selection

Organisms best suited to the environment

have the most resources for survival and reproduction

And

pass their successful traits to offspring.

What was the cause for the change in the population?

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Natural Selection: a closer look • There is variation in a trait

Due to interaction with environment

some organisms with a specific type of trait survive

other organisms without it do not survive

surviving individuals reproduce and

their offspring will inherit the same type of trait

• End result

more advantageous type of trait

will be more common in the population

This type of trait is said to be an adaptation

Hundreds of thousands of Elephant seals

once inhabited the Pacific Ocean.

The Northern population were slaughtered in the 1800s

for their blubber

By 1892, only 50 to 100 individuals were left.

1900 the Mexican and US government decided to protect them

Today, there are approximately 160,000 northern elephant seals.

Is this an example of genetic drift or natural selection

The Northern population of elephant seals

is less genetically diverse than the Southern Population.

Which population of elephant seals has a higher chance of surviving in the future?

Elephant Seals in North Pacific Ocean

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Antibiotic Resistance

Antibiotics become less effective

with successive uses

Insecticides and herbicides

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Natural Selection and Genetic drift can only happen if

there is variation within a population

What is the source of variation?

Mutations

random changes in the DNA

that can have an effect on traits

for good or for bad

A population of organisms experiences random mutations

But natural selection is non-random (one specific mutation is selected)

Natural Selection

results a population better adapted to the environment

(at least momentary)

Which one of the following statements is accurate?

a. Natural selection works on variation

already present in a population.

b. Natural selection works on non-heritable traits.

c. Individuals evolve through natural selection.

d. Organisms evolve structures that they need.

e. None of the statements are true.

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Natural selection explains how populations change through time,

but how did all the species that have ever existed came to being?

What is a species?

- population or groups of populations

- members can potentially interbreed in nature

- AND produce fertile offspring

- appearance is not important

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Fly scenario • An event splits the original

population in two

• Generations later…

• An other event brings the groups

together

But they are not interbreeding!!!

• Speciation has occurred

• Speciation:

process by which new species

come into being

New species originate as modified

descendants of other species

What can cause speciation? Geographical barrier

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Many geological and climatic events can serve as

barriers separating populations and causing speciation

Speciation

over the last 3.6 billions of years

has produced all the species that have ever lived on Earth

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IMPLICATION:

all species

are genetically related

Speciation

over the last 3.6 billions of years

has produced all the species that have ever lived on Earth

Extinction also accounts for today’s biodiversity Extinction

is the disappearance of

an entire species

from the face of the Earth.

99% of species that have existed

are extinct today

Why?

Mass extinction:

events that have wiped out

anywhere from 50% to 95%

of the species living

at that point in time

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Evolution gives us a fuller

appreciation of biodiversity

• Can the same species evolve again?

• Why are specialist species prone to extinction?

• Why should prevent species to become endangered?

• If we want to grow food successfully,

should we plant only one kind of crop?

and only one variety of that crop?

What is biodiversity?

Why is biodiversity important?

What are the treats to biodiversity?

What can be done?

What are hotspots?

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What is Biodiversity? Biodiversity, or biological diversity

Biodiversity exists on several levels:

Genetic diversity

Corn has 300 varieties

Species diversity:

One tree in the rainforest

had 1100 species of beetles

Ecosystem diversity

California has 15 ecosystems

- We do not know the total number of species

that exist today

About 1.5 million species have been described

But many more exist:

Estimates range from 3 million to 100 million

(probably 30 million)

- Why are we still so unsure of the number of species on Earth?

Some areas remain little explored

Recently scientists discovered

27 new animal species living in

Sierra Nevada National Park’s caves!!!

Species Diversity

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Species Diversity -Species are not evenly spread

among different groups

- Species go extinct naturally

-Currently Earth is undergoing 6th mass extinction

the cause is not nature but another species

- Humans have increased the extinction rate by a

factor of 1,000.

What are the threats to biodiversity?

Primary causes spell “HIPPO”:

• Habitat alteration

• Invasive species

• Pollution

• Population growth

• Overexploitation

Threats to biodiversity in

California are real.

We know of at least 21 animal species

and 34 plant species that have become

extinct in recent decades.

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H for Habitat Alteration

The greatest cause of extinction today

Accounts for 85% of

population declines of birds and mammals

Why is habitat change so damaging?

What human activities cause

habitat alteration?

Examples:

I is for Invasive species Aka Introduced species

Accidental or intentional introduction of

exotic species to new areas

Most do not get establish or expand,

but some do

Why?

What human activities

introduce foreign species?

Examples:

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Cost of invasive species to the U.S. economy

• $137 billion spent each year for ALL invasive species.

• Homeowners spend $500 million/year.

• $100 million spent to control aquatic weeds that clog

waterways.

What did it take to eradicate Caulerpa taxifolia

in California?

• $7 million

• 6 years

• Early, multi-disciplinary approach

P is for Pollution

Air and water pollution

from agricultural runoff, industrial chemicals, etc.

Why is pollution not a local but a global problem?

Examples:

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P is for Population growth Human population growth magnifies

The effects of the other elements of HIPPO:

More people means more habitat change,

more invasive species,

more pollution, more overexploitation.

O is for Overexploitation

Includes:

Overharvesting or overconsumption

what activities lead to overexploitation?

And overfishing

Examples:

8 million parrots are

exported every year

Only 10% survive

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In most cases, extinctions occur

because of a combination of factors.

Why is biodiversity important?

Organisms contribute to the welfare of humans

in many different ways

Some benefits can be quantified in economic terms

Less easy to quantify in economic terms but no less important are

ecosystem services (benefits provided by a functioning environment)

Intangible benefits in terms of recreational, aesthetic and spiritual values

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Food security from biodiversity

Many species could be used for food.

There are 50,000 varieties of edible plants

just 15 plants provide 90% of the world's food

Three of them (rice, wheat and corn) are

the staple foods of 4 billion

Quinoa has 2x more protein than rice

and Amaranth has 3x

Medicinal products from biodiversity Ten of our top 25 drugs come directly from wild plants

the rest were developed by studying wild species.

Medicines from the rainforests

Medicine for the treatment of childhood leukemia

(5% to 95%) from periwinkle plant in Madagascar

Medicines from the desert

Byetta is for treatment of diabetes from Gila monster

Medicines from the coral reefs

Yondelis is an experimental cancer drug

from a sea squirt

Powerful new pain medicine from a cone snail

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What can be done?

Conservation biology is the study and protection of biodiversity

Ex situ conservation

captive breeding

In situ conservation

protection and restoration

Which approach is ideal?

Because of limited resources,

conservationists must inevitably make a difficult decision

which ecosystems should we try to preserve?

What are hotspots?

Small area (2.3%)

+

50% plants and 40% vertebrates

Many endemic species

+

High risk of human impact

HOT SPOT

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Our Hot Spot: California Floristic Providence Only 2% of the world area has a Mediterranean climate like California

Can a business protect biodiversity?

• In Papua New Guinea: Butterfly farming

Cultivate plants for the nectar and caterpillar food

on small open garden plots near forest

Income per farmer: $1,000 ($100 average yr/pr)

• In Guatemala: Non-timber forest products

indigenous people harvest: jade palm fronds,

gum latex, allspice from the forest

= $47million yr

• In your supermarket:

Protect biodiversity with wallets

Sun coffee supports 70 bird species

vs. Shade- grown coffee 240 bird species