Ch 17 Evidence for Common Ancestry in Genetics and Molecular Biology

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Questions and Answers

What was the primary focus of Darwin's theory of biological evolution?

Describing the ecology of different species globally

Proposing how modern organisms evolved through descent from common ancestors (correct)

Classifying the 68 species of beetles he collected

Explaining the diversity of species within a local area

What was the significance of Darwin collecting fossils during his voyage?

To study the ecology of extinct species

To compare the characteristics of fossils with those of living species

To collect specimens of living species

To provide evidence for his theory of biological evolution (correct)

What pattern of diversity did Darwin observe when comparing species globally?

Different species varied in their characteristics over time

Different species had distinct ecological roles within a habitat

Different yet ecologically similar species inhabited separated, but ecologically similar, habitats around the globe (correct)

Different species occupied different habitats within the local area

What was the purpose of Darwin's five-year voyage on the HMS Beagle?

To conduct a comprehensive survey of the natural world Signup and view all the answers

What was Darwin's observation about the local plants and animals he encountered during his voyage?

They were well suited to their environment Signup and view all the answers

What was the significance of Darwin's observation that different species occupied different habitats within a local area?

It showed that species are adapted to their local environment Signup and view all the answers

What did Darwin's collection of 68 species of beetles demonstrate?

The diversity of species within a local area Signup and view all the answers

What was the underlying theme of Darwin's observations during his voyage?

The diversity of species is a result of common ancestry Signup and view all the answers

What is a key aspect of the genetic code that provides evidence of common descent?

The code is nearly identical in almost all organisms Signup and view all the answers

What is the primary function of Hox genes?

To determine the destiny of body parts Signup and view all the answers

What is the significance of the wide distribution of homologous Hox genes?

It indicates that these genes have been inherited from ancient common ancestors Signup and view all the answers

What is the result of small changes in Hox genes?

Dramatic changes in the size and shape of the structures they control Signup and view all the answers

What is the significance of the Galapagos finch study?

It shows that species can change over time through natural selection Signup and view all the answers

What is the primary mechanism by which organisms have descended from a common ancestor?

Natural selection Signup and view all the answers

What is the significance of the molecular homology of Hox genes?

It indicates that these genes have been inherited from ancient common ancestors Signup and view all the answers

What is the result of relatively minor mutations in an organism's genome?

Dramatic changes in the size and shape of the structures they control Signup and view all the answers

What was the main concern of Thomas Malthus regarding population growth?

That there wouldn't be enough living space and food for everyone Signup and view all the answers

What did Darwin realize about population growth?

That population growth applies to other organisms even more than humans Signup and view all the answers

What is the result of the struggle for existence?

Many die and only a few survive and reproduce Signup and view all the answers

What is known as differential reproductive success?

The phenomenon where some individuals reproduce more successfully than others Signup and view all the answers

What is an example of artificial selection?

Farmers selecting for breeding only trees that produce the largest fruit Signup and view all the answers

What is the result of artificial selection over time?

Trees producing even bigger fruit and cows producing even more milk Signup and view all the answers

Why did farmers select for breeding only certain trees and cows?

Because they wanted to take advantage of inherited variation Signup and view all the answers

What is the main difference between natural and artificial selection?

Natural selection is a natural process, while artificial selection is a human-induced process Signup and view all the answers

What is the purpose of tagging the infant birds in the Grants' study?

To add them to their list of known individuals Signup and view all the answers

What is the significance of the device created by the Grants to measure seed hardness?

It helps them understand the birds' adaptation to different food sources Signup and view all the answers

What is the key observation that led Darwin to hypothesize about natural selection?

The varying shapes and sizes of Galapagos finch species' beaks Signup and view all the answers

What is the significance of the Grants' documentation of natural selection in wild finch populations?

It provides evidence for the theory of evolution Signup and view all the answers

What is the broader significance of evolutionary theory in biological and biomedical sciences?

It is vital to all biological and biomedical sciences Signup and view all the answers

What is the implication of the Grants' study on our understanding of evolutionary theory?

It provides evidence that evolution is an ongoing process Signup and view all the answers

What were the birds that Darwin thought were wrens, warblers, and blackbirds actually species of?

Finches Signup and view all the answers

Who proposed important hypotheses about the age of the Earth?

James Hutton and Charles Lyell Signup and view all the answers

What was the conclusion of Hutton and Lyell's research?

The Earth is extremely old and geological processes are still occurring Signup and view all the answers

What did Hutton recognize connections between?

Geological processes and features Signup and view all the answers

What did Hutton propose happens to rock layers?

They are pushed upward, tilted, or twisted by forces beneath the Earth's surface Signup and view all the answers

What was the implication of Hutton and Lyell's research for the age of the Earth?

The Earth is much older than a few thousand years Signup and view all the answers

What was the significance of Hutton and Lyell's research?

It challenged the idea of a young Earth Signup and view all the answers

What was the main idea that influenced Darwin's thoughts on evolution?

The idea of a changing Earth Signup and view all the answers

Study Notes

Evidence for Common Ancestors

Genetics provides strong evidence for common ancestry through:
- Overwhelming similarities in the genetic code of all organisms
- Homologous genes and molecules
Life's common genetic code:
- All living cells use information coded in DNA and RNA to carry information from one generation to the next and direct protein synthesis
- Nearly identical in almost all organisms
Molecular homology:
- Hox genes determine the destiny of body parts
- Small changes in these genes can produce dramatic changes in the size and shape of the structures they control
- Wide distribution of homologous Hox genes indicates inheritance from ancient common ancestors

Testing Natural Selection

Galapagos Finches:
- Grants regularly captured, identified, and measured every individual bird on the island
Darwin's Journey:
- Joined HMS Beagle on a five-year voyage
- Developed theory of biological evolution, proposing how modern organisms evolved through descent from common ancestors
Observations from the Voyage:
- Collected 68 species of beetles
- Noted how well-suited local plants and animals were to their environment
- Wanted to explain the diversity he observed
Patterns of Diversity:
- Species vary globally (different yet ecologically similar species inhabit separated, but ecologically similar, habitats around the globe)
- Species vary locally (different, yet related, species occupy different habitats within the local area)
- Species vary over time (in addition to collecting living species, Darwin also collected fossils, noting that the fossil record included many extinct animals similar to, yet different from, living species)

Influences on Darwin's Ideas

Ancient, Changing Earth:
- Geologists James Hutton and Charles Lyell proposed important hypotheses on the age and geological processes of the Earth
- Concluded that the Earth is extremely old, and that processes that changed the Earth in the past are the same processes that operate in the present
Population Growth:
- Thomas Malthus noted that human population growth was exceeding the rate of death, causing overcrowding
- Darwin realized that if Malthus's reasoning applied to humans, it applied even more to other organisms
Artificial Selection:
- Farmers selectively breed animals with desired traits, leading to changes in offspring
- Artificial selection can lead to significant changes over time

Natural Selection

Differential Reproductive Success:
- In the struggle for existence, many die, and only a few survive and reproduce
Natural Selection in Wild Finch Populations:
- Grants documented that natural selection takes place in wild finch populations frequently, and sometimes rapidly
- Darwin hypothesized that natural selection had shaped the beaks of different bird populations as they became adapted to eat different foods

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Description

This quiz explores the evidence for common ancestry in genetics and molecular biology, highlighting similarities in genetic code and homologous genes and molecules across all organisms.