Case Study: Corridors
Part 1
1. Why is it more difficult for top carnivores to obtain sufficient energy resources than it is for animals lower on
the food chain?
Carnivores choose to only eat meat. Most of the meat is in the higher trophic levels and the plants are at the bottom. The higher trophic levels have less energy than the lower ones due to the 10% rule which is why they have difficulty obtaining sufficient energy resources.
2. What sorts of genetic changes are more common in smaller populations than large ones? Are these problematic
and, if so, how?
Genetic drift generally occurs within a smaller population. The drift is problematic due to the fact that the population WILL get larger, so large that the drift will not be able to occur anymore.
3. What term or concept is used to describe the population size of breeding animals (not the total population
size)? What factors discussed above might reduce the number of breeding jaguars below the total number?
This concept would be the effective population size. Some factors reducing the number of breeding jaguars are borders making them not able to get food.
4. Is it important for people to try to protect endangered species?
Many endangered species are beneficial to humans and some are even keystone to their ecosystem making them worth of a value of importance.
1. Why is it more difficult for top carnivores to obtain sufficient energy resources than it is for animals lower on
the food chain?
Carnivores choose to only eat meat. Most of the meat is in the higher trophic levels and the plants are at the bottom. The higher trophic levels have less energy than the lower ones due to the 10% rule which is why they have difficulty obtaining sufficient energy resources.
2. What sorts of genetic changes are more common in smaller populations than large ones? Are these problematic
and, if so, how?
Genetic drift generally occurs within a smaller population. The drift is problematic due to the fact that the population WILL get larger, so large that the drift will not be able to occur anymore.
3. What term or concept is used to describe the population size of breeding animals (not the total population
size)? What factors discussed above might reduce the number of breeding jaguars below the total number?
This concept would be the effective population size. Some factors reducing the number of breeding jaguars are borders making them not able to get food.
4. Is it important for people to try to protect endangered species?
Many endangered species are beneficial to humans and some are even keystone to their ecosystem making them worth of a value of importance.
Part II
1. What does island biogeography theory suggest about the ideal design of a nature preserve? (Think of a preserve
as a habitat island.)
This suggests that the bigger reserves are technically better than the smaller ones due to the fact that they have to be connected together with corridors.
2. What are some reasons why the number and size of nature preserves are limited? In your answer, consider what
you know about both local and international pressures (social, economic, and political).
Those factors are limited because the amount of funding, the industry, and legality are also limited to support the preserves.
3. What are some examples of corridors that already exist where you live? Th ey may not go by this name, but still
serve the same function. Th ink about areas where typical land use changes. For example, if you live in a farming
community, are there unfarmed areas that could serve as corridors? If you live in a city, which areas are not built
up and could they be corridors
One corridor around my community is the Tecelote Canyon which is very dangerous for humans to enter as animals like snakes take shelter there.
1. What does island biogeography theory suggest about the ideal design of a nature preserve? (Think of a preserve
as a habitat island.)
This suggests that the bigger reserves are technically better than the smaller ones due to the fact that they have to be connected together with corridors.
2. What are some reasons why the number and size of nature preserves are limited? In your answer, consider what
you know about both local and international pressures (social, economic, and political).
Those factors are limited because the amount of funding, the industry, and legality are also limited to support the preserves.
3. What are some examples of corridors that already exist where you live? Th ey may not go by this name, but still
serve the same function. Th ink about areas where typical land use changes. For example, if you live in a farming
community, are there unfarmed areas that could serve as corridors? If you live in a city, which areas are not built
up and could they be corridors
One corridor around my community is the Tecelote Canyon which is very dangerous for humans to enter as animals like snakes take shelter there.
Part III
1. How and why might animals move between habitat patches?
Some animals can walk on foot, some can fly such as birds. The reason as to why these animals move are probably because of the lack of resources in their last habitat patch.
2. How and why might plants move between habitat patches?
Plants might move through the movement of their seeds to be able to get more sunlight to provide food for themselves.
3. As Haddad et al. point out, we often think of forests as “good” habitat (ideal for corridors), when they could be a
barrier. What sorts of species might Haddad and colleagues be studying for which pine forest can serve as a barrier?
The forests provide a barrier for predators to reach their prey.
4. What can you predict about the species Haddad and colleagues wanted to study, based on the size and
vegetation of the habitat patches and corridors they used?
The size of the corridor will affect the movements and actions of the species.
5. Examining habitat patches 14, 15, and 16, can you predict the type of comparison Haddad and his colleagues
would make to determine whether corridors were important to the species studied? Specifically, what type of data
would you collect, and in which patches, to determine whether corridors had an influence on the species of interest?
Movement between the animals in the corridors will help determine if the corridors are important to the species. The data that you would collect would be the length of the lives of the species and their movement.
1. How and why might animals move between habitat patches?
Some animals can walk on foot, some can fly such as birds. The reason as to why these animals move are probably because of the lack of resources in their last habitat patch.
2. How and why might plants move between habitat patches?
Plants might move through the movement of their seeds to be able to get more sunlight to provide food for themselves.
3. As Haddad et al. point out, we often think of forests as “good” habitat (ideal for corridors), when they could be a
barrier. What sorts of species might Haddad and colleagues be studying for which pine forest can serve as a barrier?
The forests provide a barrier for predators to reach their prey.
4. What can you predict about the species Haddad and colleagues wanted to study, based on the size and
vegetation of the habitat patches and corridors they used?
The size of the corridor will affect the movements and actions of the species.
5. Examining habitat patches 14, 15, and 16, can you predict the type of comparison Haddad and his colleagues
would make to determine whether corridors were important to the species studied? Specifically, what type of data
would you collect, and in which patches, to determine whether corridors had an influence on the species of interest?
Movement between the animals in the corridors will help determine if the corridors are important to the species. The data that you would collect would be the length of the lives of the species and their movement.
Part IV
1. Briefly describe the overall pattern you see in the data.
The animals seem to be using the linked corridors more.
2. For which species are the results significant?
The species with significant results are plants
3. Does your answer to Question #2 suggest any patterns among species types? For example, are plants different
from animals or are butterflies different from bees? Describe the patterns and try to explain them according to
the characteristics of the taxa involved.
Plants seem to move faster than the rest. Many of the animals are using the connected corridors.
4. Haddad and colleagues conclude that “In our study, we lack data on population viability and genetic diversity,
and our dramatic increases in movement to connected patches strongly suggest, but do not demonstrate, the
value of corridors.”
(a) Do you think this statement (“suggest, but do not demonstrate”) is a fair assessment of their study? Explain
your answer.
No because this is not based on facts but on assumptions.
(b) What other data are the researchers suggesting they need to conclusively demonstrate the importance of
corridors? Do you think they are right? For example, does knowing the level of genetic variability answer
questions about long-term population survival?
The suggested data is finding biodiversity and the populations. They are right due as it shows that the corridors are protective.
(c) How could researchers collect these data? Give suggestions for several of the species in their study.
Using the technique of quadrats, they can find the spread of the species.
5. Based on what you know from the Haddad et al. study, what would be the effects of a border fence on the
population of jaguars mentioned in Part I? Explain your thinking. Specify any additional information you need
in order to make sound predictions.
The fence will cut the jaguar's movements towards their food sources making a decrease in population. As their population decreases, then the prey will increase.
1. Briefly describe the overall pattern you see in the data.
The animals seem to be using the linked corridors more.
2. For which species are the results significant?
The species with significant results are plants
3. Does your answer to Question #2 suggest any patterns among species types? For example, are plants different
from animals or are butterflies different from bees? Describe the patterns and try to explain them according to
the characteristics of the taxa involved.
Plants seem to move faster than the rest. Many of the animals are using the connected corridors.
4. Haddad and colleagues conclude that “In our study, we lack data on population viability and genetic diversity,
and our dramatic increases in movement to connected patches strongly suggest, but do not demonstrate, the
value of corridors.”
(a) Do you think this statement (“suggest, but do not demonstrate”) is a fair assessment of their study? Explain
your answer.
No because this is not based on facts but on assumptions.
(b) What other data are the researchers suggesting they need to conclusively demonstrate the importance of
corridors? Do you think they are right? For example, does knowing the level of genetic variability answer
questions about long-term population survival?
The suggested data is finding biodiversity and the populations. They are right due as it shows that the corridors are protective.
(c) How could researchers collect these data? Give suggestions for several of the species in their study.
Using the technique of quadrats, they can find the spread of the species.
5. Based on what you know from the Haddad et al. study, what would be the effects of a border fence on the
population of jaguars mentioned in Part I? Explain your thinking. Specify any additional information you need
in order to make sound predictions.
The fence will cut the jaguar's movements towards their food sources making a decrease in population. As their population decreases, then the prey will increase.