Chapter 22: Introduction to Evolution (Part 1, Week 1)

Question 1

What is a heritable change in a population of organisms from one generation to the next?

Answer 1

Evolution

Question 2

What are the two different scales of evolution and how are they defined?

Answer 2

Microevolution - Changes in a population’s gene pool, such as changes in allele frequencies or single gene, from generation to generation.

Macroevolution - Evolutionary changes that produce new species and groups of species.

Allele = one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Question 3

How do biologists define a species?

Answer 3

As a group of related organisms that share a distinctive form and are capable of interbreeding.

Question 4

Who proposed the development of evolutionary thought and some of the basic tenets of evolution in the mid-1800s?

Answer 4

British Naturalist Charles Darwin

Question 5

What did the Ukrainian-born American geneticist Theodosius Dobzhansky, an influential evolutionary scientist of the 1900s, once say?

Answer 5

Nothing in biology makes sense except in the light of evolution

Question 6

Why is evolution called a theory?

Answer 6

Because it is supported by a substantial body of evidence and because it explains a wide range of observations hence why it is viewed as scientific knowledge.

Question 7

What is the process of evolution at the level of genes and proteins?

Answer 7

Molecular Evolution

Question 8

When did scholars in Europe begin a revolution that created the basis of empirical and scientific thought?

Answer 8

The 1600s

Question 9

What is empirical thought?

Answer 9

It relies on observation to form an idea or hypothesis rather than trying to understand life from a nonphysical or spiritual point of view.

Question 10

Who in the mid - to - late 1600s was the first scientist to carry out a thorough study of the living world that developed an early classification system for plants and animals based on anatomy and physiology?

He also established the modern concept of a species, noting that organisms of one species do not interbreed with members of another, and used it as the basic unit of his classification system.

Answer 10

English Naturalist John Ray

Question 11

What was the belief towards “human perfection?”

Answer 11

That all living things evolved in a continously upward direction, Evolutionary changes that produce new species and groups of species.

Question 12

Bottom line: The systemic classification of John Ray and the Swedish Naturalist, Carolus Linnaeus, did not propose evolutionary change leads to the formation of new species but helped scholars do what?

Answer 12

It helped scholars of this period PERCIEVE the similarities and differences among living organisms.

Question 13

In the late 1700s, French Zoologist Georges Buffon, proposed what but hide his views in a 44-volume series of books in natural history?

Answer 13

He suggested that life-forms are not fixed and unchanging.

Question 14

(1700s) Who was the French naturalist who suggested an intimate relationship between variation and evolution and by examining fossils, he realized that some species had remained the same over a millenia and others had changed?

Answer 14

Jean-Baptiste Lamarck. This proposal was an evolutionary change over many generations in response to the environment.

Question 15

Who was a contemporary of Buffon and Lamarck, and as a physician was an advocate of evolutionary change?

Answer 15

Erasmus Darwin, the grandfather of Charles Darwin.

Question 16

Who played a central role in developing the theory that existing species have evolved from pre-existing ones?

Answer 16

Charles Darwin

Question 17

How was Darwin’s unique perspective and his ability to formulate evolutionary theory shaped?

Answer 17

Several different fields of study such as his time in geology and population growth as well as his own observations.

Question 18

(2) What were the two main hypotheses from Geology that helped shape Darwin’s view of the world?

Answer 18

Catastrophism and uniformitaranism.

Between the great catastrophies that shaped the geological structure of the Earth and the changes that resulted from reoccuring events must have taken a GREAT deal of time!

This helped Darwin postulate that evolution were changes of large periods of time and changes that were a product of great ecological changes.

Question 19

How was Darwin’s thinking influenced by a paper published in 1798 called “An Essay on the Principle of Population” by Thomas Malthus?

Malthus asserted that the population size of humans, can at best, increase linearly due to increased land usage and improvements in agriculture, whereas our reproductive potential increases exponetionally (doubling each generation).

He argued that famine, war, and disease, especially among the poor, keep population growth within existing resources.

Answer 19

This helped Darwin believe that not all members of any population will survive and reproduce.

Question 20

What was Darwin’s mission abord the HMS Beagle from 1831 to 1836?

Answer 20

To map the southern coastline of South America and take oceanographic measurements. He also recorded information about the weather, geological feautures, plants, animals, fossils, rocks, minerals, and indigenous people.

Question 21

When did Darwin formulate his theory of evolution?

Answer 21

1840s

Question 22

What type of biological creature did Darwin decided to study for himself and become an expert on?

Answer 22

The barnacle.

Question 23

Who was also working on a manuscript, as well as Darwin, a British naturalist working in the East Indies on the same ideas concerning evolution?

Answer 23

Alfred Wallace

Question 24

How did Darwin express his concept of evolution as?

Answer 24

The theory of descent with modifications through variation and natural selection.

Question 25

What does the term evolution denote?

Answer 25

Change

Question 26

What are the two factors that allows evolution to occur from generation to generation?

Answer 26

Genetic variation and natural selection.

Question 27

T/F The genetic basis for variation was understood at the time Darwin proposed his theory of evolution?

Answer 27

False.

It was not known at the time that variation is due to different types of genetic changes such as random mutations in genes

He did however observe that offspring resembled their parents more so then an unrelated individuals. Therefore, he did assume that some traits are passed from parent to offspring.

Question 28

In each generation, many more offspring are usually produced than will survive and reproduce.

Why is this often the case? And what governs this?

Answer 28

Resources in the environment are limiting for an organism’s survival.

The process of NATURAL SELECTION, individuals with heritable traits that make them better suited to their native environment tend to flourish and reproduce, whereas other individuals are less likely to survive and reproduce. As a result of natural selection, certain traits that favor reproductive success become more prevalent in a population over time.

Question 29

What is an example of natural selection with finches, their beak size, and migrating to an island with bigger seeds?

Answer 29

Variations exists in beak sizes among the migrating birds. The seeds at the distant island are bigger than what is on the mainland.

The birds, with larger beaks, would be able to acquire food more easily than the birds that migrated with smaller beaks. Therefore, the finches with smaller beaks, would have a smaller survivable rate to reproduce with the smaller beak trait. The finches with the bigger beak would be the more dominant variation of finch and would ultimately result in a new species.

Question 30

The phrase “an organism evolves” is incorrect. Explain why.

Answer 30

A single organism does not evolve. Populations may evolve from one generation to the next due to differences in reproductive success.

Question 31

How do antibiotics like streptomycin, tetracycline, and amoxicillin inhibit bacterial growth?

Answer 31

They interfere with processes such as the synthesis of the cell wall, bacterial translation, or vital metabolic pathways.

Question 32

What are the two ways a strain of bacteria becomes antibiotic resistant?

Answer 32

• A new mutation in a bacterium may render the antibiotic ineffective.

Ex. Suppose an antibitoic blocks bacterial growth by binding to a protin that is needed for cell wall synthesis and inhibiting its function. A mutation could occur in the bacterial gene that encodes this protein, altering the protein’s structure in a way that prevents the antibiotic from binding.

• A bacterium may acquire a gene that confers antibiotic resistance via horizontal gene transfer.

Ex. A bacterium may acquire a gene that encodes an enzyme that breaks down the antibiotic, thereby rendering it ineffective.

Question 33

What does MRSA stand for and what has it become much more resistant to?

Answer 33

Methicillin-resistant S. aureus (MRSA) strain. This is a type of bacterium called Staphylococcus aureus. Methicillin is a antibiotic used to combat staph but in the last 20 years, but now roughly

Question 34

What features of Daphne Major make it a suitable field site for studying the effects of natural selection?

Answer 34

The island has a moderate level of isolation but is located near enough to the mainland to have some migrants. The island is an undisturbed habitat, so the researchers would not have to consider the effects of human activity on the study. Finally, the island had an existing population of ground finches that would serve as the subjects of the study over many generations.

Question 35

Why is beak depth in finches a good trait for a study of natural selection? What environmental conditions were important to allowing the Grants to collect information concerning natural selection?

Answer 35

First, the researchers were able to show that beak depth is a genetic trait that has variation in the population. Second, the depth of the beak is an indicator of the types of seeds the birds can eat. The birds with larger beaks can eat larger and drier seeds; therefore, changes in the types of seeds available could act as a selective force on the bird population.

During the study period, annual changes in rainfall occurred, which affected the seed sizes produced by the plants on the island. In the drier year, fewer small seeds were produced, so the birds would have to eat larger, drier seeds.

Question 36

Analyze the results of the Grants’ study, and explain what they mean with regard to natural selection and evolution.

Answer 36

The researchers found that following the drought of 1977, the average beak depth in the finch population increased.

This indicated that birds with larger beaks were better able to adapt to the environmental changes due to the drought and produce more offspring. This is direct evidence of the phenomenon of natural selection.

Question 37

How were the Grants able to observe changes in a finch population?

Answer 37

Because of a drought and the growth of bigger seeds as a result.

Question 38

Historically, where did the first evidence of biological evolution come from?

Answer 38

Studies of fossil records, the distribution of related species on the planet, selective breeding experiments, and the comparison of similiar anatomincal features in different species.

Question 39

What is biogeography?

Answer 39

The study of the geographic distribution of extinct and living species.

Ex. Unique species found on islands and other remote areas have arisen because the species in these locations have evolved in isolation from the rest of the world

Question 40

What are another two types of evidence of biological evolution not previously captured?

Answer 40

Convergent evolution (two different species from different lineages sometimes become anatomically similiar because they occupy similar environments) and homologies (anatomical, developmental, and molecular similarities like structure, embryonic development, and DNA sequences from common ancestors)

Question 41

What are fossils and what do they provide biologists?

Answer 41

Preserved remains of past life. They provide evidence and create extensive records AND provide detailed information regarding evolutionary change in a series of related organisms.

Question 42

What is an organism that provides a link between earlier and later forms in evolution?

Answer 42

Transitional form like the T. roseae (fishapod)

Question 43

What refers to species that are naturally found only in a particular place or region?

Answer 43

Endemic species

Question 44

What is an example of an endemic island species?

The study of the geographic distribution of extinct and living species. Concept Check.

Hint: California, Santa Barbara channel, Channel islands

Answer 44

The island fox, which lives on the Channel islands is a small fox. The island fox evolved from the mainland grey fox.

18,000 years ago, the channel froze and some of the mainland gray foxes made their way to the Channel islands. After the ice age, the foxes were stranded on the island and eventually evolved into the island fox.

This is an example of island dwarfing, a phenomenon in which the size of large animals on an isolated island shrinks dramatically over many generations. Also a result of natural selection.

Question 45

Give an example of isolated continents and two types of animals not found elsewhere.

Answer 45

The first placental mammals, which have a long internal gestation and give birth to well developed offspring, evolved much later after continental drift.

Hence why austrailia, other than a few bats and rodents, lack any of the larger, terrestrial placental mammals. However, they have a large population (more than 100 species) of kangaroos, koalas, and other marsupials, most of which are not found anywhere else.

Their offspring are born very premature and are raised in a pouch where the mammary glands exist.

Question 46

What is the similarity that results in the process of natural selection where the study of plants and animals have similiar characteristics but are not closely related evolutionarily?

Answer 46

Convergent evolution.

Question 47

What is an example of convergent evolution?

Answer 47

Both the giant ant eater in S. AMerica and the echidna, in Austrailia, have a long snout and tongue. Both species independently evolved these adaptations that enable them to feed on ants.

The giant anteater is a placental mammal, wheres the echidna is an egg-laying mammal known as a monotreme, so they are not closely related evolutionarily.

Question 48

Fun Fact: What enables certain fish species to survive the subfreezing temperatures of Artic and Antartic waters by inhibiting the formation of ice crystals in body fluids?

Answer 48

Antifreeze proteins

Question 49

What is a structure that is the result of convergent evolution? Such structures have arisen independently, two or more times, because species have occupied similar types of environments on Earth.

Answer 49

Analogous structure, or convergent traits.

Question 50

What are programs and procedures designed to modify traits in domesticated species?

Answer 50

Selective breeding, or artificial selection, is related to natural selection

Question 51

Fun Fact: What was Charles Darwin’s observations influenced by?

Answer 51

Pigeon Breeders

Question 52

Fun Fact: American geneticists were able to indicate that the size of dogs may be determined by alleles in the Igf1 gene that encodes what growth hormone?

Answer 52

Insulin-like growth factor 1

Question 53

What does the term homology mean in Biology?

Answer 53

Refers to a similarity that occurs due to descent from a common ancestor.

Question 54

With anatomical homologies, what in vertebraes have a strikingly similiar pattern of bone arrangements?

What are these similar structures called?

Answer 54

The forelimbs.

Homologous structures

Question 55

What are the different functions that the forearm has developed amoung various vertebrates?

Answer 55

Grasping, walking, flying, swimming, and climbing.

Question 56

What is an anatomical feature that has no current function but resembles a structure of a presumed ancestor?

Give some examples.

Answer 56

Vestigial structures.

Humans and the bony tail in embryo and muscles to wiggle ears in adults.

Whales and skeletal remains of a pelvis.

Manatees and their fingernails on the flippers.

Question 57

What two-word phrase captures the similarities of two different species during the embryonic stages even though when adults, they have nothing in common?

What is an example between fish and humans?

Answer 57

Developmental Homologies

Ex. In human emrbyonic development, several feautures are seen in the embryo that are not present at birth.

Human embryos have rudimentary gill ridges like a fish embryo, even though humans recieve oxygen from the umbilical cord. This indicates that humans evolved from an aquatic species that had gill slits.

Human embryos also have bony tails. An ancestor of the human lineage possessed a tail.

Question 58

What are the similarities at the molecular level that indicate that living species evolved from a common ancestor or interrelated group of ancestors?

Answer 58

Molecular homologies

Question 59

What two molecular homology does the majority of species have?

Answer 59

All species use oxygen meaning that have similair proteins that together make up an electron transport chain and ATP synthase.

Nearly all living organisms can break down glucose via a metabolic pathway.

Question 60

What checkpoint protein of the cell cycle that can initiate DNA repair has commonalities between 5 mammals, one bird, and three fish?

This evidence highlights the interrelatedness from a common ancestor of many different species of organisms.

Answer 60

The p53 gene, that encodes the p53 protein, a checkpoint protein of the cell cycle.

More Info: The two monkey amino acid sequences have a 95% to humans while the three fish, with 40% - 50% similarity with humans, are almost identical among the three fish species.