Chapter 22 – Descent with ModificationAP BIOLOGY – BRETHREN CHRISTIAN HS

MS. WHIPPLE

1. Who is Charles Darwin? Describe how the events of his life contribute to his development of the theory of Natural Selection?

Charles Darwin (1809–1882) was born in western England. As a boy, he developed a consuming interest in nature.

When Darwin was 16, his father sent him to the University of Edinburgh to study medicine.

Darwin left Edinburgh without a degree and enrolled at Cambridge University with the intent of becoming a clergyman. At that time, most naturalists and scientists belonged to the clergy

and viewed the world in the context of natural theology.

Darwin received his B.A. in 1831. Section 22.2

1. Who is Charles Darwin? Describe how the events of his life contribute to his development of the theory of Natural Selection?

After graduation Darwin joined the survey ship HMS Beagle as ship naturalist and conversation companion to Captain Robert FitzRoy.

FitzRoy chose Darwin because of his education, and because his age and social class were similar to that of the captain.

Field research helped Darwin frame his view of life.

The primary mission of the five-year voyage of the Beagle was to chart poorly known stretches of the South American coastline.

Darwin had the freedom to explore extensively on shore while the crew surveyed the coast.

He collected thousands of specimens of the exotic and diverse flora and fauna of South America.

Section 22.2

1. Who is Charles Darwin? Describe how the events of his life contribute to his development of the theory of Natural Selection?

Darwin noted that the plants and animals of South America were very distinct from those of Europe.

Organisms from temperate regions of South America more closely resembled those from the tropics of South America than those from temperate regions of Europe.

Further, South American fossils, though different from modern species, more closely resembled modern species from South America than those from Europe.

While on the Beagle, Darwin read Lyell’s Principles of Geology.

He experienced geological change firsthand when a violent earthquake rocked the coast of Chile, causing the coastline to rise by several feet.

He found fossils of ocean organisms high in the Andes and inferred that the rocks containing the fossils had been raised there by a series of similar earthquakes.

These observations reinforced Darwin’s acceptance of Lyell’s ideas and led him to doubt the traditional view of a young and static Earth.

Section 22.2

1. Who is Charles Darwin? Describe how the events of his life contribute to his development of the theory of Natural Selection?

Darwin’s interest in the geographic distribution of species was further stimulated by the Beagle’s visit to the Galapagos, a group of young volcanic islands 900 km west of the South American coast. Darwin was fascinated by the unusual organisms found there.

After his return to England, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland.

He hypothesized that the islands had been colonized by plants and animals from the mainland that had subsequently diversified on the different islands.

Section 22.2

Fig. 22-5

NORTHAMERICA

EUROPE

AFRICA

AUSTRALIA

GREATBRITAIN

SOUTHAMERICA

ATLANTICOCEAN

PACIFICOCEAN Cape of

Good Hope

Tierra del Fuego

Cape HornTasmania

NewZealand

An

des

Equator

TheGalápagosIslands

Pinta

MarchenaGenovesa

SantiagoDaphneIslands

PinzónFernandina

IsabelaSan

Cristobal

SantaFe

SantaCruz

Florenza Española

Section 22.2

2. What are adaptations? How did the observation of these adaptations help Darwin develop his theory?

In reassessing his observations, Darwin perceived adaptation to the environment and the origin of new species as closely related processes

From studies made years after Darwin’s voyage, biologists have concluded that this is indeed what happened to the Galápagos finches Section 22.2

Fig. 22-6

(a) Cactus-eater (c) Seed-eater

(b) Insect-eater Section 22.2

3. What is the theory of Natural Selection as explained by Darwin?

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individual because of those traits (or the interaction of traits)

Section 22.2

4. Describe your understanding of Descent with Modification?

Darwin developed two main ideas:

Descent with modification explains life’s unity and diversity

Natural selection is a cause of adaptive evolution

The phrase descent with modification summarized Darwin’s perception of the unity of life

The phrase refers to the view that all organisms are related through descent from an ancestor that lived in the remote past

In the Darwinian view, the history of life is like a tree with branches representing life’s diversity

Darwin’s theory meshed well with the hierarchy of Linnaeus (Taxonomy)

Section 22.2

Fig. 22-8

Hyracoidea(Hyraxes)

Sirenia(Manateesand relatives)

Moeritherium

Barytherium

Deinotherium

Mammut

Elephas maximus(Asia)

Stegodon

Mammuthus

Loxodontaafricana(Africa)

Loxodonta cyclotis(Africa)

010425.52434

Millions of years ago Years ago

Platybelodon

Section 22.2

5. Scientists estimate that over ______________ of all species that have ever lived are now extinct.

98% of all species that have ever lived are now extinct. WAY TO GO HUMANS…we made the 2% still living!!

Section 22.2

6. What is Artificial Selection? Give me one example.

Darwin noted that humans have modified other species by selecting and breeding individuals with desired traits, a process called artificial selection

Dogs, Broccoli, Corn, Bananas, Cows, Chickens, Turkeys, Horses, Pigs, Donkeys, Cauliflower, Mice, Apples, Oranges, Cats, Guinea Pigs, Hamsters, Potatoes, Carrots, Brussel Sprouts…so many more!!!

Section 22.2

Fig. 22-9

Kale

Kohlrabi

Brussels sprouts

Leaves

Stem

Wild mustard

Flowersand stems

Broccoli

Cauliflower

Flowerclusters

Cabbage

Terminalbud

Lateralbuds

Brassica olerasia

var. capitata var. gemmifera

var. acephala

var. botrytis

var. italica var. gogylodesSection 22.2

7. Write your understanding of Darwin’s two observations and two inferences. Observation #1: Members of a population often vary greatly in their traits. Observation #2: All species can produce more offspring than their

environment can support and many of these offspring fail to survive and reproduce.

Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals "The higher chances of survival, the more offspring they have"

Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations "Those that survive will bring the favorable traits with them"

Section 22.2

Fig. 22-UN1

Observations

Over time, favorable traitsaccumulate in the population.

Inferences

and

Individuals in a populationvary in their heritable

characteristics.

Organisms produce moreoffspring than the

environment can support.

Individuals that are well suitedto their environment tend to leave

more offspring than other individuals

The End

8. What is meant by the phrase “Individuals do not evolve, populations do”

Individuals do not evolve; populations evolve over time

Natural selection can only increase or decrease heritable traits in a population. Each individual is stuck with the heritable traits (genes) they were born with, an individual cannot generally change their genes over their lifetime.

Adaptations vary with different environmentsSection 22.2

1. Explain how rapid evolution was shown with the Soapberry bugs of in central and southern Florida.

Native to southern US In Florida, native host plant is balloon vine

which occurs primarily on southern tip of Florida, on the Florida Keys, and less commonly, in central Florida

Bugs feed by piercing the fruit with beak and inserting it into the seeds

Flat-podded golden rain tree introduced to central Florida in 1926

This new Rain tree fruits are much thinner than balloon vine fruits.

Soapberry bugs in Central Florida started using rain trees as a host plant

Populations of bugs living on thin-fruited rain trees evolved shorter beaks

Soapberry bugs in c. Florida started using rain trees as a host plant

Populations of bugs living on thin-fruited rain trees evolved shorter beaks

1. Explain how rapid evolution was shown with the Soapberry bugs of in central and southern Florida.

Fig. 2.1(a) Evolutionary change in soapberry bugs

Fig. 2.1(b) Evolutionary change in soapberry bugs

2. How do drug-resistant pathogens show ongoing Natural Selection in our society?

Antibiotic resistance is an evolutionary phenomenon of tremendous clinical significance.

Early in the 20th century, a variety of antibiotics, used to treat bacterial diseases, were developed. An understanding of evolution is helpful to understand where these antibiotics come

from to begin with…many, such as penicillin, were evolved by fungi, over millions of years, to kill off their bacterial competitors.

Humans have co-opted them for our own purposes. Since the 20th century, the bacterial pathogens have evolved resistance to

our antibiotics, because extensive use of these drugs has caused very strong natural selection in favor of mutations which favor antibiotic resistance. For instance, many MRSA strains are resistant to many common antibiotics.

3. Describe your understanding of the following key concepts of Natural Selection:

“Natural selection is a process of editing, not a creative mechanism”

“Natural selection depends on time and place”

4. What is Homology? How is this used in the study of evolution?

Homology is similarity resulting from common ancestry

Studying Homology can give us insight into evolutionary relationships between organisms.

5. What are Homologous Structures? How is the mammalian forearm an example?

Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Humerus

Radius

Ulna

Carpals

Metacarpals

Phalanges

Human Cat Whale Bat

5. What are Homologous Structures? How is the mammalian forearm an example?

EXTRA!! Comparative embryology reveals anatomical homologies not visible in adult organisms

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Pharyngealpouches

Post-analtail

Chick embryo (LM) Human embryo

6. What are Vestigial Structures? What are two examples.

Vestigial structures are remnants of features that served important functions in the organism’s ancestors.

Some examples are the leg bones in a whales hind end and possibly the human appendix.

7. What is an evolutionary tree? How is this made?

The Darwinian concept of an evolutionary tree of life can explain homologies

Evolutionary trees are hypotheses about the relationships among different groups

Evolutionary trees can be made using different types of data, for example, anatomical and DNA sequence data

Fig. 22-19

Hawks andother birds

Ostriches

Crocodiles

Lizardsand snakes

Amphibians

Mammals

Lungfishes

Tetrapod limbs

Amnion

Feathers

Homologouscharacteristic

Branch point(common ancestor)

Tetrapo

ds

Am

nio

tes

Bird

s

6

5

4

3

2

1

8. What is Convergent Evolution? Give me one example.

Convergent evolution is the evolution of similar, or analogous, features in distantly related groups

Analogous traits arise when groups independently adapt to similar environments in similar ways

Convergent evolution does not provide information about ancestry

9. Describe Analogous Structures. Give me one example.

Analogous structures are structures that have the same function but not the same evolutionary descent.

Fig. 22-20

Sugarglider

Flyingsquirrel

AUSTRALIA

NORTHAMERICA

10. Describe the evidence for evolution that comes from Biogeograpy? What is Pangea?

Darwin’s observations of biogeography, the geographic distribution of species, formed an important part of his theory of evolution

Islands have many endemic species that are often closely related to species on the nearest mainland or island

Earth’s continents were formerly united in a single large continent called Pangaea, but have since separated by continental drift

An understanding of continent movement and modern distribution of species allows us to predict when and where different groups evolved

11. Endemic species in an area are:

An Endemic Species is one that is only found in that region and nowhere else in the world.

Sources:

http://jan.ucc.nau.edu/~pservice/bio435_660/bio435_660_chap2.ppt

http://www.google.ca/url?sa=t&rct=j&q=&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.uic.edu%2Fclasses%2Fbios%2Fbios101%2FEvidence%2520for%2520Evolution.ppt&ei=NbX4VMyFIoHuoATTrYHACw&usg=AFQjCNHesK8-Zaq9ubm0UFOI2_jwrlArHg&bvm=bv.87611401,d.cGU