nerve activates contraction - st. johns county school...

The Pieta

Who made this one???

Arches National Park

And who made this one???

Science is WHAT?? 3 min.

http://www.youtube.com/watch?v=9Cd36WJ79z4&feature=player_embedded

How did you get here?

• Let’s check someone’s family tree.

• Is this how you got here?

• Is there another way to answer the question?

• Has it always been answered this way?

• Pick another explanation from here.

http://www.bigmyth.com/2_eng_myths.html

The evolution of intelligent life on earth:

•Man learns to use

simple machines –

Part 1

../Animations/Brother.wmv

Let’s listen to Ken Miller, an evolutionary

biologist from Brown University

• Go here to the 2006 Informal

Lectures and select section 2 – 6

(12 min.) or 9. Here he explains

why this is such an important

topic, and it all goes back to the

nature of what science is and

isn’t.

http://www.hhmi.org/biointeractive/fossils-genes-and-mousetraps

• On November 24, 1859, Charles Darwin published On

the Origin of Species by Means of Natural Selection.

• Darwin made two points in The Origin of Species:

• Today’s organisms descended from ancestral

species.

• They have changed over time.

• Natural selection is the mechanism by which these

changes occur.

Introduction

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

What evolution is NOT…

• Evolution is not the study of the ORIGIN of life

on earth,

• although

• This also involves evolution, in a sense, but an

evolution of chemicals. Let’s watch… if time.

4 min.

http://www.pbs.org/wgbh/nova/evolution/origins-life.html

Why, why, why…

• Why would anyone, Darwin or otherwise, have

any reason to think that living things may have

changed as time has gone by?

• What evidence would make them think this?

• Let’s get our hands on some.

• Darwin’s views were influenced by fossils, the relics

or impressions of organisms from the past,

mineralized in sedimentary rocks.

• How do fossils form??? Check it out. 2m

• Such fossils were largely undiscovered

until the 1700’s.


Fig. 22.2 Fig. 22.4

http://www.youtube.com/watch?v=oZcv45wPF2g

• Paleontology, the study of fossils,

was largely developed by Georges

Cuvier, a French anatomist.

How can we use isotopes to tell

how old these fossils are? Let’s

do some math.


• Fossils show a pattern of change that is supported by other evidence, like DNA comparisons.

• Special creation explanations state that life has not changed from the time of its creation.

• This is not what paleontologists actually observe. Life has changed a lot!!

• Here’s the scoop from some dino poop…


• What are “transition fossils”?

• Here’s a whale of a tale… 1:20

• Now let’s take a closer look.


Fig. 22.17

http://www.youtube.com/watch?v=8cn0kf8mhS4&feature=related

And here is Archeopteryx, still the king of

transition fossils. New video from HHMI 18:00

https://www.youtube.com/watch?v=z4nuWLd2ivc&feature=youtu.be

And here is the hoatzin, a modern bird with

claws on its wings, like Archeopteryx!

• What’s the best explanation? That is why this is

evidence for how evolution works!

Wrap it up

• Let’s revisit this science and religion issue

(notice I didn’t say “science vs. religion”) one

more time. 4:00 Can there be another

explanation for what you just heard? Can

science and intelligent design coexist?

• Here is the short version of animal evolution.

http://www.youtube.com/watch?v=XzMh7gEKNmM

https://www.youtube.com/watch?v=OIWde6OpVZU

Quick fossil summary

• Fossils show us two things

• Change has happened. Living things are not like they

used to be. Evolution has occurred.

• In many cases, the fossil record tells us exactly what

kind of changes have occurred, as in those transition

fossils.

• Soooooooo, since the fossil record agrees with the

explanation for the history of life on earth that we call

the process of evolution, the fossil record qualifies as

proof that this process is how change comes about.

• When you see two people who look very much

alike, you assume they are related. The more alike

they look, the more closely related you think they

are.

• Why does your mind come to this conclusion?

• And do you have the same thoughts when you look

at your dog?

• A pine tree? The mold on your shower curtain?

2. Homology - similarity suggests

relatedness; the study of real estate


• Similarities in characteristics resulting from

common ancestry is known as homology.

• There are three main categories of similarities:

• Big structures like arms and legs.

• The way that a thing develops after it is

conceived.

• Little structures (molecules) like DNA and

ATP and the reactions they are involved in.


• For example, the forelimbs of human, cats, whales,

and bats share the same skeletal elements, but

different functions because they diverged

from the ancestral tetrapod forelimb.

• Homologous structures. Classic example.


Fig. 22.14

• The whale’s flipper is not a new

structure, it is a remodeled leg.

• Tinkering?

• Such structures are often not perfect.

• How good are your knees and

back??

• How about a plant example??


• Vestigial organs are great proof.

• For example, the skeletons of some

snakes and of fossil whales retain

vestiges of the pelvis and leg bones of

walking ancestors.

• Do you have any vestigial structures?


• Sometimes, homologies that are not obvious in

adult organisms become evident when we look

at embryonic development.

• Hey swimmers, have you ever wished that

you had gills?

• Let’s look at some neat video of embryonic

development. 5:00


http://www.youtube.com/watch?v=h3Lkac890c0

• And how about molecules???

• Do you have any molecules that

are homologous to chemicals in

related organisms?


• If two species have genes and proteins

with sequences that match closely, the

sequences have probably been copied

from a common ancestor.

• Comparing chemicals agrees with fossil

and other evidence in terms of how the

history of life has played out.

• How about a worksheet??? A

cladogram? Now the whale activity!


3. Actual documented examples of

evolution happening in a short time.


• The evolution of resistance to insecticides in hundreds

of insect species is a classic example of evolution by

natural selection in action.

• Is this “smoking gun” evidence???


Fig. 22.12

Another example:

• The use of antibiotics has resulted in a

tremendous increase in the number of bacteria

which are resistant to their deadly action. This

is also a great example of why it is important

to understand how evolution works – it

allows to have a better chance to fight such

disease causers as this tuberculosis bacteria.

6:20

• Here’s another – experimental evidence! 5:40

• And another – Cats evolving before our eyes.

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_6.html

http://www.youtube.com/watch?v=LBv6-XORcLg&feature=related

../Animations/Violence_on_TV.wmv

• Category 4: - the geographical distribution

of species - biogeography - first suggested

evolution to Darwin. “Where are the

rabbits?”, he once wondered while looking

out on the plains of Argentina.

• How do you catch a unique rabbit???


• For example, while the sugar glider and flying

squirrel are similar, they are not closely related.

• The sugar glider from Australia is more closely related to

other marsupial mammals from Australia than to

the flying squirrel, a placental mammal from North

America. What’s the best explanation???

• The resemblance

between them is an

example of

convergent

evolution.

• Divergent???


Fig. 22.15

Alfred Wallace is the father of

biogeography. Here’s Wallace’s Line

Here’s what the Line means

• He noticed that organisms on one side of the line

were totally different than those on the other side,

even on islands that were only 20 miles apart. He

hypothesized that islands on each side must have

been connected in the past. Most notable were

big placental mammals on the west side of the

line and marsupials on the east.

• The best explanation for why this is is the

evolutionary one, thus this is support for that

explanation/theory.

That evolution occurs, then, is proven by

four great categories of evidence:

• The fossil record.

• Similarities in different existing organisms that suggest descent from common ancestors.

• Actual, documented examples, such as resistence in insects and bacteria, as well as long term studies such as one on Darwin’s finches that is ongoing.

• Biogeography

• James Hutton, a Scottish geologist, proposed a theory of

gradualism.

• Later, Charles Lyell, proposed a theory of

uniformitarianism.

Theories of geological gradualism helped

clear the path for evolutionary biologists


• Paleontology, the study of fossils, was largely

developed by Georges Cuvier, a French anatomist.

• Instead of evolution, Cuvier advocated

catastrophism.


• These ideas greatly influenced Darwin.

• First, if geological changes result from slow, continuous

processes, rather than sudden events, then the Earth

must be far older than the 6000 years assigned by

theologians from biblical inference.

• Second, slow and subtle processes persisting for long

periods of time can add up to substantial change.


• In 1809, Jean Baptiste Lamarck published a

theory of evolution based on his observations of

fossil invertebrates in the Natural History

Museum of Paris.

• Lamarck was convinced new forms evolved from

common ancestors, just like Darwin and many others

did. His work added much evidence to the fossil

record.

• But he missed the boat when he guessed the reason for

the change. Or did he?

Lamarck placed fossils in an evolutionary

context


• Central to Lamarck’s theory on why these

changes have occurred were the concepts of

use and disuse of parts and of inheritance of

acquired characteristics.

• He thought giraffes did what????


• However, the reasons he gave for why things

change was off - there is no evidence that

acquired characteristics can be inherited.

• Acquired traits (e.g., bigger biceps, longer

necks) do not change the genes transmitted by

gametes to offspring.

• Or do they…? Science is at it again.


• Charles Darwin (1809-1882) was born in western England.

• He studied to be a doctor.

• Then a clergyman.

Introduction


• Darwin received his degree in 1831.

• After graduation Darwin was recommended to be

the conversation companion to Captain Robert

FitzRoy, preparing the survey ship Beagle for a

voyage around the world.

• The world would never be the same.


• Imagine the adventure of five years at sea.

1. Field research helped Darwin frame

his view of life


Fig. 22.5

• Darwin noted that the plants and animals of

South America were very distinct from those

of Europe.

• Organisms from temperate regions of South

America were more similar to those from

the tropics of South America than to those

from temperate regions of Europe.

• Further, South American fossils more

closely resembled modern species from that

continent than those from Europe.


• The origin of the fauna of the Galapagos, 900

km west of the South American coast,

especially puzzled Darwin.

• On further study after his voyage, Darwin

noted that while most of the animal species

on the Galapagos lived nowhere else, they

resembled species living on the South

American mainland.

• It seemed that the islands had been

colonized by plants and animals from the

mainland that had then diversified on the

different islands.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

• While on the Beagle, Darwin read Lyell’s

Principles of Geology.

• Lyell’s ideas and his observations on the

voyage lead Darwin to doubt the

common view that the Earth was static

and only a few thousand years old.

• Instead, he was coming to the

conclusion that the Earth was

• (1) very old and

• (2) constantly changing.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

• Finches became one of his famous examples.

• These are from Cornell’s Ornithology Lab.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 22.6

• Why did Darwin hesitate to publish his theories??

• Who was Alfred Wallace??

• Why is Darwin more famous??


• Darwinism has a dual meaning.

• It refers to evolution as the explanation for life’s

unity and diversity.

• It also refers to the Darwinian concept of natural

selection as the cause of organisms changing over

time..

On The Origin of Species has two main

points: evolution occurs, and natural

selection is its mechanism


• Central to Darwin’s view of the evolution of life

is descent with modification.

• All present day organisms are related through

descent from common ancestors, like whales

and hippos from Mesonychids.

• Descendents have modifications which have

allowed them to survive in their environments.

• The history of life is like a tree.

• Closely related species, the twigs of the

tree, shared the same line of descent until

their recent divergence from a common

ancestor.


Copyright © 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 22.7

• This evolutionary tree of the elephant family is

based on evidence from fossils.

• Let’s practice some cladograms like this, if we

haven’t already.

• The second major point that Darwin

made is that natural selection is the

reason for changes.

• Ernst Mayr, an evolutionary

biologist, has dissected the logic of

Darwin’s theory into three inferences

based on five observations.

• (Be able to explain this logic)


• Observation #1:All species, not just ones like the fungus

below, have such great potential to reproduce. Examples?

• Observation #2: Populations tend to remain stable in size.


• Observation #3: Environmental

resources are limited.

• Logical conclusion: 1, 2 and 3

lead to a struggle for existence.

Not all offspring are going to

make it.

Fig. 22.8


• How about that essay by

Thomas Malthus in 1798.

•Jonathon Swift wrote a

famous reply to Malthus.

•Let’s look at some

population ecology…

• If B = D then there is zero population

growth (ZPG).

• Under ideal conditions, a population

grows slowly at first (the lag phase),

because there are few reproducing

individuals, then very rapidly.

• Exponential population growth is

said to be happening.


Fig. 52.9


• Typically, unlimited resources are rare.

• Population growth is therefore

regulated by carrying capacity (K),

which is the maximum stable

population size a particular

environment can support.

2. The logistic model of population growth

incorporates the concept of carrying

capacity


• This is the pattern - lag, exponential growth, then a

limiting factor (food, space, water, pedators, etc.)

slows it down to logistic growth and keeps the

population around the carrying capacity.

Fig. 52.11



• Observation #4: Great variety exists.

• Observation #5: Much of this variation is heritable.

Fig. 22.9


• Logical conclusion #2: Survival in the struggle for

existence is not random, but depends in large part

on what traits an individual has.

• Those individuals whose inherited characteristics best fit

them to their environment are likely to leave more

offspring than less fit individuals.

• Logical inference #3: This unequal ability of

individuals to survive and reproduce will lead to a

gradual change in a population, with favorable

characteristics accumulating over the generations.

If only redheads were allowed to have more than

one child, what would you notice as time passed?

• Is Michael Phelps the most “fit”?

• Does it mean Ultimate Fighting???

• Could more subtle and passive factors be involved?

How about that “Survival of the Fittest” thing?


• Darwinian fitness is the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

• So who is most fit - ?

•

• Fitness = reproductive success.



• Darwin fooled around with pigeons!!!

How did this influence him???

Fig. 22.11


• Darwin’s ideas can be summarized in three points.

• Natural selection is differential success in reproduction

(unequal ability of individuals to survive and reproduce).

• Natural selection occurs through an interaction between

the environment and the variations among the individual

organisms making up a population.

• The product of natural selection is the adaptation of

populations of organisms to their environment, they didn’t

TRY to make it happen.

• More redheads is a product of their being selected to

reproduce more.

• For example, related species of insects called

mantids have diverse shapes and colors that evolved in

different environments.


Fig. 22.10

What separated Darwin from others is

his conclusion that variations occur

• AT RANDOM!!!

• Not because of a desire or a need, and not because of a special creation of a mystical nature (a supernatural explanation).

• Given enough time, he argued, random changes acted on by the selection process can result in magnificent adaptations, possibly appearing to be the result of some intelligent design. Monkeys with typewriters?

• If the design is indeed intelligent, he argued, it came about through the process of natural selection, not supernaturally, but naturally. This, he argued, was the creator’s method! Science can explain this – the HOW.

• In each generation, environmental factors favor

some variations over others.

•An organism receives variations from its parents

randomly. The selection process itself, however, is

not random at all.

•It depends on how a trait fits in with its environment.

• This increase in the frequency of the

favored traits in a population is how

the population changes; it is, by

definition, evolution.


• Darwin envisioned the diversity

of life as evolving by a gradual

accumulation (Hutton’s idea) of

minute changes through the

actions of natural selection

operating over vast spans of

time (Lyell and the geologists’

idea).

The process of Natural Selection in a nutshell:

• More things are born than can live to reproduce, because the earth’s resources are not infinite. This creates competition –Darwin’s “struggle to survive”.

• These organisms have differences that are heritable. These variations occur by chance; they are random.

• Some of these variations are adaptive, they “match up” with aspects of the environment (selection pressures) that allow those that have them to reproduce more. This “match up” is not at all random.

• The average characteristics of a group are those that have been passed on more (selected for) and the group changes as this process continues.


• While natural selection involves interactions

between individual organisms and their

environment, it is not individuals, but

populations that evolve. Individuals do what?

• Populations are defined as a group of interbreeding

individuals of a single species that share a common

geographic area. Example?

• Evolution is measured as the change in relative

proportions of variation in a population over a

succession of generations (longer average neck

length as time goes by - not for each giraffe, but for

the group as a whole).

Bottom Line:• Groups of organisms (populations) change their

average characteristics (evolve) as a result ofgoing through this process by which the characteristics which lead to reproductive success (are adaptive) get passed down more often.

• They don’t change because they need to, want to, or have to so that they can survive. If they could do this, no populations would ever become extinct.

Here, I think, is what leads to many

misconceptions…

• We commonly say that organisms adapt to their

environment. Biology textbooks even list this as a

characteristic of life – the ability to adapt to its

environment, along with metabolism, growth,

reproduction, etc.

• When people first start to learn this, they seem to

naturally infer that the organisms are DOING this

“adapting” thing themselves, just like they DO

metabolism, growth, reproduction, etc. Can you

understand that living groups become adapted by having

the process happen to them, not by doing it??

If YOU are asked to explain Natural Selection:

• Explain that these three facts set the table for the process to occur:

1. More things are born than can live to reproduce.

2. The earth’s resources are not infinite.

3. These organisms have differences that are heritable. These variations occur by chance; they are random.

Then explain the result when the situation is as described above:

• Some of the variations “match up” with aspects of the environment (selection pressures) that allow those that have them to reproduce more. This is not at all random.

• As the generations go by, more and more individuals have the adaptive traits passed to them, and in this way the average characteristics of the group change – the group evolves.

So don’t use the terms…“need to”, “want to” or “have to” to explain why populations evolve, and don’t say that things change “so that” they can survive, live, eat the leaves from the tops of trees, etc.

• This is called Lamarckian thinking.

• All these terms suggest organisms change on purpose, either by their own will or that of a higher power. Neither explanation holds up to scientific scrutiny. If a higher power is at work (a religious question), it is working through the process of natural selection.

• Let’s watch an example, rock pocket mice. (11 min.).

• And now – a worksheet!

http://www.hhmi.org/biointeractive/shortfilms/

And here is a famous biologist (on the

right), Sean Carroll.

• Arguments by individuals dismissing the Darwinian view as “just a theory” suffer from two flaws.

• First, it fails to separate Darwin’s two claims: (1) that modern species evolved from ancestral forms and, (2) that natural selection is the main mechanism for this evolution.

• The conclusion that life has evolved is supported by an abundance of evidence, as we have seen.

• This is fact, not theory. The theory explainsthese facts.

4. What is theoretical about the Darwinian

view of life?


• The “just a theory” arguments concern only

Darwin’s second point, his theory of natural

selection as the reason for the fact of evolution.

• Here lies the second flaw, as the term theory in

colloquial use is closer to the concept of a “hypothesis”

in science.

• In science, a theory is more comprehensive than a

hypothesis.

• A theory, such as Newton’s theory of gravitation or

Darwin’s theory of natural selection, accounts for many

facts and attempts to explain a great variety of

phenomena and is supported by a great deal of

evidence. (Notice I didn’t say “proven”).


• By attributing the diversity of life to natural causes

rather than

to supernatural

creation, Darwin

gave biology a

sound, scientific

basis.

• As Darwin said,

“There is grandeur

in this view of life.”


Fig. 22.18

A population of termites initially consists of

darkly colored and brightly colored members. After several

generations, the termite population consists almost entirely of

darkly colored members because the brightly colored

termites are easier for a predatory species of insectivores to

locate. This situation is an example of :

A. The evolution of a new species

B. Natural selection

C. Artificial selection

D. Adaptive radiation

Scientists use the similarities and differences among

species to determine how they are related. Which of

the following is NOT used by scientists to determine

relationships among species?

A. Analogous structures

B. Vestigial structures

C. Cellular structures

D. Homologous structures

Many species of animals use hemoglobin to transport oxygen

from their lungs to their cells, but they have some differences

in their hemoglobin molecules. The hemoglobin molecule in

humans is very similar to the hemoglobin in gorillas, and very

different from the hemoglobin in mice. Which inference is

best supported by these observations? A. Gorillas are closely related to mice, but humans are not

B. Humans and gorillas are closely related to each other but not to mice

C. Large animals need a specific kind of hemoglobin to transport oxygen throughout their large bodies

D. Humans and gorillas have similar hemoglobin because they are adapted to eat similar foods

For centuries, dog breeders have chosen to breed particular dogs to pass

on, or even enhance, desirable traits. This is an example of:

A. Speciation

B. Artificial selection

C. Natural selection

D. Sexual selection

How is natural selection in the evolution

of long necks in giraffes best explained?

A. Shorted-necked giraffes were killed by long-

necked giraffes

B. B. Giraffe necks grew longer because of the

bone structure of the animals.

C. Giraffes with longer necks survived because

they were better suited to the environment

D. Long-necked giraffes mated only with other

long-necked giraffes

Of the following, which best illustrates natural

selection?

A. An organism with favorable genetic variations

will tend to survive and breed successfully

B. A population monopolizes all of the resources in

its habitat, forcing other species to migrate

C. A community whose members work together

utilizes all existing resources and migratory routes

D. The largest organisms in a species receive the

only breeding opportunities

If a paleontologist finds fossils of many different species existing in

the same area at approximately the same time, the paleontologist

can conclude that the ecosystem in this area had a high degree of:

A. Climatic variation

B. Episodic speciation

C. Biological diversity

D. Geographic isolation

Which of the following is true, because of

comparative embryology?

• A. a frog embryo resembles an adult frog.

• B. Both turtle and human embryos have a tail.

• C. the embryos of all animals appear different.

• D. male and female eagle embryos have wings.

Within a species of fish, variations exist in color, size & the

speed at which individuals can swim. Which variation would

be the least likely to be passed on to future generations of the

species?

• A. color of marking which aid in camouflage

• B. reproduction by laying large numbers of

eggs

• C. swimming speed which is less than that of

predators

• D. size which enables hiding among small

rocks & in rock crevices

Which of the following statements about natural

selection is true?

• A. Natural selection works on individuals,

rather than a population of organisms

• B. All organisms within a species are

genetically identical.

• C. Offspring can inherit traits of an organism

which that organism develops during its life

• D. Organisms which survive to reproduce can

pass favorable variations on to offspring

A population of termites initially consists of

darkly colored and brightly colored members. After several

generations, the termite population consists almost entirely of

darkly colored members because the brightly colored termites are

easier for a predatory species of insectivores to locate. This

situation is an example of :

A. The evolution of a new species

B. Natural selection

C. Artificial selection

D. Adaptive radiation

For centuries, dog breeders have chosen to breed particular

dogs to pass on, or even enhance, desirable traits. This is an

example of:

A. Speciation

B. Artificial selection

C. Natural selection

D. Sexual selection

What 2 processes result in variations that commonly

influence the evolution of sexually reproducing species?

• A. mitosis and natural selection

• B. extinction and natural selection

• C. mutation and genetic recombination

• D. environmental selection and selective

breeding

How is natural selection in the evolution of

long necks in giraffes best explained?

A. Shorted-necked giraffes were killed by long-

necked giraffes

B. B. Giraffe necks grew longer because of the

bone structure of the animals.

C. Giraffes with longer necks survived because

they were better suited to the environment

D. Long-necked giraffes mated only with other

long-necked giraffes

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