Ecology Lecture: Neisseria Gonorrhoeae, Evolution, Photosynthesis, Extinction - Prof. Lawr | Study notes Ecology and Environment

Ecology Lecture Outline and Study Guide Morehouse College BIO 320

217

Key to Section I Problems and Sample Examination Questions

1. The sexually transmitted disease, gonorrhea, is caused by the bacterium Neisseria

gonorrhoeae. This disease used to be treatable with the antibiotic penicillin. Penicillin was widely

prescribed for that purpose and was even dispensed to individuals thought to be at risk of infection

who were not actually infected. In 1970, the first strains of penicillin resistant Neisseria were

isolated from patients with gonorrhea. In 1985, the percentage of gonorrhea cases in the United

States caused by penicillin resistant Neisseria was 1% (9000 cases of penicillin resistance) but by

1990 the percentage had increased to almost 9% (59,000 cases of penicillin resistance). The

percentage of Neisseria infections that are resistant to penicillin continues to increase.

Describe the roles of mutation and natural selection in the phenotypic change observed in Neisseria

gonorrhoeae.

Mutation is the source of the initial variation in Neisseria that resulted in one or more cells becoming

resistant to penicillin. The use of penicillin, which selectively eliminates penicillin sensitive cells and leaves the

resistant cells is the form of natural selection that has caused the frequency of penicillin resistant Neisseria infections

to increase.

What kind of selection occurred in Neisseria gonorrhoeae populations? Draw a frequency

histogram to illustrate your answer.

Exposure to penicillin causes directional selection in Neisseria populations in which there is heritable

variation in sensitivity to penicillin. The shaded area of the population frequency distributions for penicillin

sensitivity represent that part of Neisseria populations that are subject to the strongest negative selection. The

vertical line indicates the mean for the population alive at time 1, and provides a reference for the change occurring in

the population.

List and describe the requirements for evolution by natural selection.

Phenotypic variation: differences between the phenotypes of individuals in a population.

Differential survival and reproduction: individuals with different phenotypes have different probabilities of surviving

and reproducing. These differences are caused by natural selection.

Heritability: phenotypic variation must be caused by underlying genetic variation if selection is to result in

evolutionary change.

Differential production of descendants: this must be the outcome of differential survival and reproduction of

individuals in a population.

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Key to Section I Problems and Sample Examination Questions

1. The sexually transmitted disease, gonorrhea, is caused by the bacterium Neisseria

gonorrhoeae. This disease used to be treatable with the antibiotic penicillin. Penicillin was widely

prescribed for that purpose and was even dispensed to individuals thought to be at risk of infection

who were not actually infected. In 1970, the first strains of penicillin resistant Neisseria were

isolated from patients with gonorrhea. In 1985, the percentage of gonorrhea cases in the United

States caused by penicillin resistant Neisseria was 1% (9000 cases of penicillin resistance) but by

1990 the percentage had increased to almost 9% (59,000 cases of penicillin resistance). The

percentage of Neisseria infections that are resistant to penicillin continues to increase.

Describe the roles of mutation and natural selection in the phenotypic change observed in Neisseria

gonorrhoeae.

Mutation is the source of the initial variation in Neisseria that resulted in one or more cells becoming resistant to penicillin. The use of penicillin, which selectively eliminates penicillin sensitive cells and leaves the resistant cells is the form of natural selection that has caused the frequency of penicillin resistant Neisseria infections to increase.

What kind of selection occurred in Neisseria gonorrhoeae populations? Draw a frequency

histogram to illustrate your answer.

Exposure to penicillin causes directional selection in Neisseria populations in which there is heritable variation in sensitivity to penicillin. The shaded area of the population frequency distributions for penicillin sensitivity represent that part of Neisseria populations that are subject to the strongest negative selection. The vertical line indicates the mean for the population alive at time 1, and provides a reference for the change occurring in the population.

List and describe the requirements for evolution by natural selection.

Phenotypic variation: differences between the phenotypes of individuals in a population. Differential survival and reproduction: individuals with different phenotypes have different probabilities of surviving and reproducing. These differences are caused by natural selection. Heritability: phenotypic variation must be caused by underlying genetic variation if selection is to result in evolutionary change. Differential production of descendants: this must be the outcome of differential survival and reproduction of individuals in a population.

2. Extinction is a macroevolutionary process in which all individuals in a given group (species)

stop leaving descendents, and eventually disappear. Is this an important phenomenon in the

history of life on earth? Explain.

Yes, extinction is an important phenomenon. There have been six geological periods of mass extinction in which as much as 50% of animal families and as much as 95% of species have gone extinct. Life would look very different today if the mass extinctions had not occurred.

Name five factors that may increase the likelihood of extinction.

rarity, poor dispersal ability, high degree of specialization, high population density variability, trophic status as a top level consumer, poor longevity, low intrisic rate of population growth

2. What is the function of photosynthesis specializations such as C 4 photosynthesis and CAM

in some plant species? Explain your answer.

Both these photosynthesis specializations are means of conserving water by minimizing the loss of water from the stomata in leaves. In C 4 photosynthesis, there is a spatial separation of carbon dioxide capture and the Calvin Cycle. In CAM photosynthesis, there is a temporal separation of carbon dioxide capture and the Calvin Cycle.

4. Name and describe Darwin’s Hostile Forces of Nature. What is the relationship between the

Darwin’s Hostile Forces and ecological limiting conditions and resources? What is the role of the

Hostile Forces and limiting factors in the process of Natural Selection?

The Hostile Forces of Nature are: Predators, organisms that consume and often kill their prey; Parasites and Diseases, these are also predators, often symbionts, that consume and may kill their host; Climate, long-term patterns in abiotic environmental conditions and resources; Weather, short-term patterns in abiotic environmental conditions and resources; Resource Shortages, any resource that is necessary to an organism that is in short supply, including mates for sexually reproducing organisms. The Hostile Forces of Nature are the ecological limiting conditions and resources. The Hostile Forces of Nature are the causes for differences between individuals in survival and reproduction. The Hostile Forces of Nature are the limiting conditions and resources that cause Natural Selection.

5. What is the compensation point in photosynthesis? Under what circumstances in nature would

photosynthetic organisms be at the compensation point? Draw a fully labeled graph showing the

rates of photosynthesis and respiration (as dependent variables) to help illustrate your answer.

The compensation point is the light intensity at which the photosynthetic rate equals the rate of cellular respiration. In nature, the compensation point may be reached at the water depth defining the bottom of the euphotic zone, or in the understory of a very dense forest.

Oxygen gas is essential for cellular respiration in most organisms yet this gas is readily available in terrestrial environments. In terrestrial environments, oxygen can therefore be considered: a. a limiting resource b. a required resource

c. a biotic condition

d. an abiotic condition

Ecology Lecture: Neisseria Gonorrhoeae, Evolution, Photosynthesis, Extinction - Prof. Lawr, Study notes of Ecology and Environment

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Download Ecology Lecture: Neisseria Gonorrhoeae, Evolution, Photosynthesis, Extinction - Prof. Lawr and more Study notes Ecology and Environment in PDF only on Docsity!

Key to Section I Problems and Sample Examination Questions

1. The sexually transmitted disease, gonorrhea, is caused by the bacterium Neisseria

gonorrhoeae. This disease used to be treatable with the antibiotic penicillin. Penicillin was widely

prescribed for that purpose and was even dispensed to individuals thought to be at risk of infection

who were not actually infected. In 1970, the first strains of penicillin resistant Neisseria were

isolated from patients with gonorrhea. In 1985, the percentage of gonorrhea cases in the United

States caused by penicillin resistant Neisseria was 1% (9000 cases of penicillin resistance) but by

1990 the percentage had increased to almost 9% (59,000 cases of penicillin resistance). The

percentage of Neisseria infections that are resistant to penicillin continues to increase.

Describe the roles of mutation and natural selection in the phenotypic change observed in Neisseria

gonorrhoeae.

What kind of selection occurred in Neisseria gonorrhoeae populations? Draw a frequency

histogram to illustrate your answer.

List and describe the requirements for evolution by natural selection.

2. Extinction is a macroevolutionary process in which all individuals in a given group (species)

stop leaving descendents, and eventually disappear. Is this an important phenomenon in the

history of life on earth? Explain.

Name five factors that may increase the likelihood of extinction.

2. What is the function of photosynthesis specializations such as C 4 photosynthesis and CAM

in some plant species? Explain your answer.

4. Name and describe Darwin’s Hostile Forces of Nature. What is the relationship between the

Darwin’s Hostile Forces and ecological limiting conditions and resources? What is the role of the

Hostile Forces and limiting factors in the process of Natural Selection?

5. What is the compensation point in photosynthesis? Under what circumstances in nature would

photosynthetic organisms be at the compensation point? Draw a fully labeled graph showing the

rates of photosynthesis and respiration (as dependent variables) to help illustrate your answer.

c. a biotic condition