AP Biology Chapter 22- Descent with Modification- A Darwinian View of Life

Define evolution broadly and then give a narrower definition, as discussed in the overview.

Evolution: Descent with modification; the idea that living species are descendants of ancestral species that were different from the present-day ones. Also defined more narrowly as the change in the genetic composition of a population from generation to generation

Aristotle and Scala Naturae:

Aristotle viewed species as fixed. Through his observations of nature, Aristotle recognized "affinities" among organisms. He concluded that life-forms could be arranged on a ladder, or scale, of increasing complexity, called the scala naturae. Each form, perfect and permanent, had its allotted rung on this ladder.

The Old Testament:

The Old Testament holds that species were individually designed by God and therefore perfect.

Carolus Linnaeus:

Linnaeus adopted a nested classification system, grouping similar species into increasingly general categories. Linnaeus, adhering to the Old Testament belief that all species were designed by God, did not ascribe the resemblances among species to evolutionary kinship, but rather to the pattern of their creation.

Explain the role of fossils in rock strata as a window to life in earlier times.

Many fossils are found in sedimentary rocks formed from the sand and mud that settle to the bottom of seas, lakes, swamps, and other aquatic habitats. New layers of sediment cover older ones and compress them into superimposed layers of rock called strata. The fossils in particular strata provide a glimpse of some of the organisms that populated Earth at the time that the layer formed

How would Georges Cuvier have explained the appearance of the record of life shown in the rock
strata?

Cuvier opposed the idea of evolution. He advocated catastrophism, the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present. Cuvier speculated that each boundary between strata represented a catastrophe, such as a flood, that had destroyed many of the species living at that time.

James Hutton and Charles Lyell were geologists whose ideas strongly influenced Darwin’s thinking. What were the ideas each of them contributed?

James Hutton : Hutton proposed that Earth’s geologic features could be explained by gradual mechanisms still operating today, such as valley formed by rivers.

Charles Lyell:

Lyell incorporated Hutton’s thinking into his principle of uniformitarianism, which states that mechanisms of change are constant over time. Lyell proposed that the same geologic processes are operating today as in the past, and at the same rate.

What is the importance of the principle of uniformitarianism?
.

If geologic change results from slow, continuous actions rather than from sudden events, then Earth must be much older than the widely accepted age of a few thousand years

7. Jean-Baptiste de Lamarck proposed a mechanism for how life changes over time. Explain the two principles of his mechanism.

use and disuse: – The idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate. inheritance of acquired:- characteristics: This idea states that an organism could pass these modifications of use and disuse to its offspring

Although Lamarck’s mechanism of evolution does not explain the changes in species over
time, his thinking has been influential. What is considered to be the great importance of his
ideas?

Lamarck recognized that the match of organisms to their environments can be explained by gradual evolutionary change rather than special creation.

Charles Darwin proposed that the mechanism of evolution is natural selection and that it explains how adaptations arise. What are adaptations? Give two examples of adaptations.

Adaptations are inherited characteristics of organisms that enhance their survival and reproduction in specific environments. Possible examples include the mottled coloration of a fawn that allows it to blend with its environment, or the sharp talons and beaks of birds of prey so well suited for predation.

10. Explain the process of natural selection.

In the process of natural selection, individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

.11. Summarize Darwin’s observations that drive changes in species over time.
.1)Variations in traits exist.

2. These variations (traits) are heritable

3.Species overproduce.

4. There is competition for resources;
not all offspring survive

1)Variation in color and spot pattern of Asian ladybird beetles 2)Variation in closely related species of elephants; offspring resemble close relatives more than other members of a population 3)Dandelions produce thousands of seeds 4) Not all dandelion seeds germinate or survive to maturity

From these four observations, what two inferences did Darwin make?

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. 2. The unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

13. What can differential reproductive success lead to over time?

Over time, this process will increase the frequency of individuals with favorable adaptations and hence refine the match between organisms and their environment, which may give rise to new species

14. Explain the reasoning behind the phrase "survival of the fittest".

Individuals do not evolve. Populations evolve.

MRSA is in the news today because it is becoming increasingly more common. What is it?

MRSA is methicillin-resistant Staphylococcus aureus, a flesh-eating strain of bacterium

15. Explain how research on soapberry bugs demonstrates observable evolutionary change.

Researchers have studied beak length evolution in soapberry bug populations that feed on plants introduced to Louisiana, Oklahoma, and Australia. In each of these locations, the fruit of the introduced plants is larger than the fruit of the native plant. Thus, in populations feeding on introduced species in these regions, data collected in field studies suggested that natural selection had resulted in the evolution of longer beak length.

How did it become so dangerous? Explain the evolution of MRSA’s resistance to methicillin.

MRSA became dangerous because, over time, doctors used a variety of antibiotics, such as penicillin, to combat MRSA. Each time a new antibiotic was used to fight the disease, some S.aureus populations would develop resistance to the new drug. In 1959, doctors used the powerful antibiotic methicillin. Members of the S. aureus population that were resistant to methicillin reproduced at higher rates, leading to the spread of methicillin-resistant S. aureus (MRSA).

Do antibiotics cause bacteria to become resistant? Explain your response.

No. A drug does not create resistant pathogens; it selects for resistant individuals that are already present in the population

19. Make a list of four evidences for evolution. 1. evolution can be observed directly,

2. homology: similarity resulting from common ancestry, forming a nested pattern

3. fossil record: documents pattern of evolution

4. biogeography: geographic distribution of species

1. such as the evolution of resistant strains of bacteria 2. similarity resulting from common ancestry, forming a nested pattern 3.documents pattern of evolution 4. geographic distribution of species

How does the fossil record give evidence for evolution?

The fossil record documents the pattern of evolution, showing that past organisms differed from present-day organisms and that many species have become extinct

Homologous structures

Structures in different species that are similar because of common ancestry. For example, mammalian forelimbs.

Vestigial structures

A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors. For example, skeletons of some snakes retain vestiges of the pelvis and leg bones.

Analogous structures

Having characteristics that are similar because of convergent evolution, nothomology. For example, the wing of a butterfly and wing of a bat both make flight possible

22. How do homologous structures give evidence for evolution?

.

Homologous structures represent variations on a structural theme that was present in the common ancestors of a species.

23. What is summarized in an evolutionary tree?

An evolutionary tree reflects evolutionary relationships among groups of organisms

Organisms that are only distantly related can resemble each other. Explain convergent evolution, and describe how analogous structures can arise.

Convergent evolution is the independent evolution of similar features in different lineages. In such examples as the marsupials of Australia, in which species share features because of convergent evolution, the resemblance is said to be analogous. Analogous features share similar function, but not common ancestry.

Convergent evolution might be summarized like this: Similar problem, similar solution. Can you give two examples of convergent evolution?

Answers will vary but may include the sugar glider and the flying squirrel, and the evolution of wings in birds and bats.

What is biogeography? How is it affected by continental drift and the presence of endemic
species?

Biogeography is the geographic distribution of species. The geographic distribution of organisms is influenced by many factors, including continental drift, the slow movement of Earth’s movement over time, and the presence of endemic species, species that are found nowhere else in the world