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Does the amount of UV light reaching the Earth vary in a predictable manner

15. Which niche was most diverse? Why do you think this is the case?


Biol 1100L Population Ecology Lab 2

Name:_______________________________ Section:____

Part 1. Population Study

A summary of mortality, survivorship, and ex- pectation of further life by age, is called a life table. The most straight forward type of life ta- ble starts with a cohort of young organisms and follows their fortunes through their lives, until the last one dies. Because cohort data are usu- ally difficult to obtain, most life tables are calcu- lated using other kinds of information. If we can obtain mortality rates by age of a population we can, after the appropriate assumptions and cal- culations, construct a life table (called a time- specific table, versus the age-specific cohort table). A frequent approach, and the one used here, is to use age at death to estimate mortal- ity rates and calculate the other vital statistics from that. Tables produced in this way are age- specific, even though the cohort is composite, made up of individuals that started life in differ- ent years. The study of human populations is called de- mography and is a branch of science called population ecology. A population is defined as a species (interbreeding individuals) within a de- fined area. In this lab, we will be exploring the Idaho Falls population. Using the data that was collected from the Rose Hill Cemetery of Idaho

Table 2-1. Life table of the Idaho Falls population pre-1930 and post-1970. Where x is the beginning age of the age class, nx is the number alive (survivors) at age x, lx is the proportion of survivors at age x, dx is the number dying (mortality )within the age class x, and qx is the mortality rate (that is, dx/nx).

Table 2-2. Data collected from the Idaho Falls Rose Hills Cemetery during Spring 2010. Also known as mortality (dx) pre-1930 and post-1970 of the Idaho Falls popula- tion.

Falls (Table 2-1), the life table (Table 2-2), and the survivorship curves (Fig. 2-1) constructed you will answer a few questions.


Biol 1100L Population Ecology Lab 2

1. Look at circle A on Figure 2-1. Why do you think there is a steep decrease in survivorship for the pre-1930 population?

2. Comparing pre-1930 and post-1970 populations, has the proportion of people surviving through an age class increased or decreased for the Idaho Falls population (excluding the last two age classes)?

3. What has changed since pre-1930 to make an increase in survivorship possible?

4. Do you think this is similar for the entire US population?

Figure 2-1. Proportion (as a percentage) of survivors (lx) at age x of the Idaho Falls population pre-1930 and post-1970.



Biol 1100L Population Ecology Lab 2

Part 2. Ecological Footprint

Lifestyle in advanced nations like the US depends significantly on the direct or indirect burning of fossil fuels. Many people in less developed nations, however, do not depend on large-scaled burning of fossil fuels. Imagine a subsistence farmer in an undeveloped country living in a mud hut without electricity or running water. The family is fed from the small herd of animals and crops adjacent to its dwelling. The family does not own a car, and travel to the next village requires an ox and a cart. The family does not own any electrical appliances or electronic media. Consider another family in a more developed part of the world but less developed than North America or Western Europe. The family has electricity in its small home, but it does not own a car and has just bought its first TV. The father rides his bike to a nearby village for work. The mother walks to the local village market three times a week for local produce and meat. The atmospheric CO2 level was approximately 280 parts per million (ppm) before the industrial revolu- tion and is now 393 ppm (in 2005 it was 387 ppm). A greenhouse gas, CO2, is emitted from a variety of sources, many of them associated with the burning of fossil fuels. For example, when you drive a car, the exhaust emissions include CO2. When you heat or cool your home the required energy often comes from the burning of fossil fuels in power stations. But have you ever stopped to think that your diet may play a role in CO2 emissions? If you eat meat and shop for it at a supermarket chain, there is strong chance that the source of your T-bone steak is a distant slaughterhouse. In winter, the lettuce that makes up the bulk of the salad you eat may be shipped from tropical locations. Your steak and lettuce than travel by truck to reach your supermarket delicatessen or produce counter, contributing to CO2 emissions along the way. In 2007 the biosphere had 11.9 billion hectares of biologically productive space corresponding to roughly one quarter of the planet’s surface. These 11.9 billion hectares of biologically productive space include 2.4 billion hectares of ocean and inland water and 9.1 billion hectares of land. The land space is composed of 1.6 billion hectares of cropland, 3.4 billion hectares of grazing land, 3.9 billion hectares of forest land, and 0.3 billion hectares of built-up land.

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