2.1 Intro to Population Ecology

Question 1

What is a population?

Answer 1

a group of individuals of the same species, in the same area, and at the same time

Question 2

What is population density?

Answer 2

the total number of organisms in an area compared to the volume they occupy

Question 3

What is population distribution?

Answer 3

the spatial relationship between members of a population within a habitat

Question 4

What is a uniform distribution? Why are some populations in this type of distribution?

Answer 4

A uniform distribution is one in which the individuals are mostly spaced equidistantly. This type of distribution is common in areas with scarce resources, which causes animals to become very territorial.

Question 5

What are some examples of uniform distributions?

Answer 5

Sage plants secrete a toxin that kills all plants in their radius, causing them to be equally spaced in a field. Tigers are also an example of a uniform distribution, they hunt and travel alone, and they are highly territorial over their land and resources.

Question 6

What is a clumped distribution? Why are some populations in this type of distribution?

Answer 6

Clumped distributions are found in clusters. They are in fact clumped, as the name suggests. This type of distribution can be found in individuals who value social interactions. For example, some individuals are usually found in herds or flocks. Predators also gravitate toward areas with more prey and resources, which causes the population to become more clumped.

Question 7

What are some examples of a clumped distribution?

Answer 7

Herds of bison are found in clumps. Packs of wolves are also examples of a clumped distribution. Also, some plants have seeds that drop directly to the ground, which forms clumps around the original plant.

Question 8

What is a random distribution? Why are some populations in this type of distribution?

Answer 8

Random distributions are just as the name implies, random. This means that you can find these individuals sporadically in their habitat. Uniform distributions are usually found in areas with abundant resources, without many social interactions between individuals.

Question 9

What are some examples of a random distribution?

Answer 9

Dandelions are found in a random distribution. This is because their seeds are carried by the wind, so they land in random spots throughout a field.

Question 10

List the three types of population distributions from least common to most common.

Answer 10

Random, Uniform, Clumped

Question 11

What are some of the common factors that affect the population?

Answer 11

sunlight, temperature, water, soil, nutrients, and other living organisms in the area

Question 12

What is the goal of population ecology?

Answer 12

to understand factors that influence size and populations, and to be able to to manage and control these populations.

Question 13

What is the optimal distribution used for random sampling? Why?

Answer 13

Random sampling is best used for uniform population distributions. This is because the individuals will be spread evenly across the habitat, making getting more accurate samples and a more precise population size estimate easier.

Question 14

Explain how to calculate population size using quadrats.

Answer 14

1. calculate the sum of the individuals in the samples that you took
2. divide by the total area that the samples take up
3. multiply by the total area of the field

Question 15

Calculate population size using the following data points (pretend that I have a graph, and it is organized in quadrants):
Each square measures 2m x 2m, there are 100 squares in total
10, 6, 8, 15, 13

Answer 15

1. 10 + 6 + 8 + 15 + 13 = 52
2. 52 / 20 = 2.6
3. 2.6 x 100
   population density: 2.6 ind / 1m^2
   population size: 260

Question 16

Explain how to calculate population size using the mark and recapture technique.

Answer 16

total number of marked / total population size

marked in recapture / total recaptured

Question 17

Calculate population size in the mark and recapture technique:
A biologist originally marked 50 butterflies in Central Park. Over a week-long period butterfly traps caught 150 butterflies. Of those 150, 10 were found to have tags.

Answer 17

x = population size
50 originally marked / x
10 marked in recapture / 150 recaptured
population size: 750 butterflies

Question 18

True or False:
Animals found in the uniform distribution have abundant resources.

Answer 18

False. Animals found in uniform distributions usually have scarce resources, causing them to become very territorial.

Question 19

True or False:
Direct Counting is a method used very rarely to count a population size.

Answer 19

True. Direct counting involves a biologist physically going out into the field and counting every individual. This is impractical, and it is rarely done.