Biology 311: Chapter 56: Conservation Biology and Global Change: Reading Guide Flashcards

Ecologists are particularly concerned about the impact of human activities on which four processes of the biosphere?

Trophic structures, energy flow, chemical cycling, and natural disturbance.

What is conservation biology?

Conservation biology integrates ecology, physiology, molecular biology, genetics, and evolutionary biology to conserve biological diversity at all levels.

Genetic diversity

If one population becomes extinct, then a species may have lost some of the genetic diversity that makes microevolution possible. This erosion of genetic diversity in turn reduces the adaptive potential of the species.

Species diversity

As more species are lost to extinction, species diversity de creases. Many species that are threatened could potentially provide food, fibers, and medicines for human use, making bi odiversity a crucial human resource. Additionally, each loss of a species means the loss of unique genes, some of which may code for enormously useful proteins.

Ecosystem diversity

There is growing evidence that the functioning of ecosystems, and hence their capacity to perform services, is linked to bio diversity. As human activities reduce biodiversity, we are re ducing the capacity of the planet's ecosystems to perform processes critical to our own survival.

Extinction is a natural phenomenon that has been occurring since life first evolved. What aspect of extinction is of concern to scientists today? Cite data to support this concern.

Because of the many interactions between members of different species in an ecosystem, the extinction of populations of one species can have a negative impact on other species in the ecosystems (see Figure 54.20). For instance, bats called "flying foxes" are important pollinators and seed dispersers in the Pacific Islands, where they are increasingly hunted as a luxury food (Figure 56.4). Conservation biologists fear that the extinction of flying foxes would also harm the native plants of the Samoan Islands, where four-fifths of the tree species depend on flying foxes for pollination or seed dispersal.

Explain the difference between an endangered species and a threatened species.

An endangered species is one that is in danger of extinction throughout all or a significant portion of its range.

A threatened species is one that is considered likely to become endangered in the near future.

Make a list of five ways healthy ecosystems and biodiversity benefit humans.

1. Healthy ecosystems purify our air and water.

2. Healthy ecosystems detoxify and decompose our wastes.

3. Health ecosystems reduce the impacts of extreme weather and flooding.

4. Healthy ecosystems pollinate our crops, control pests, and create and preserve our soils.

5. The biodiversity of a healthy ecosystem allows our planet's ecosystems to perform processes critical to our own survival.

Habitat loss

When no alternative habitat is available or a species is unable to move, habitat loss may mean extinction. The IUCN implicates destruction of physical habitat for 73% of the species that have become extinct, endangered, vulnerable, or rare in the last few hundred years.

Introduced species

Free from the predators, parasites, and pathogens that limit their population in their native habitats, such transplanted species may spread rapidly through a new region, often disrupting their new community by preying on native organisms or outcompeting them for resources. Introduced species contribute to approxi mately 40% of extinctions recorded since 1750.

Overharvesting

Overharvesting endangers species in restricted habitats or with slow reproductive rates, thus decreasing biodiversity

Global change

This threat to biodiversity alters the fabric of Earth's ecosystems at regional to global scales. Changes in climate, atmosphere, chemistry, and broad ecological systems reduce the capacity of Earth to sustain life.

1. Brown tree snake

Since its introduction, 12 species of birds and 6 species of liz ards that the snakes ate have become extinct on Guam, which had no native snakes.

2. Kudzu

Has taken over large areas of landscape in the southern United States. Climbs to the top of very tall trees, and blankets them and eventually may kill them. Aggressive competi tor for light and water.

3. European starling

Quickly spread across North America, where its population ex ceeds 100 million, displacing many native songbirds

4. Chestnut blight

Destroyed the American chestnut, which was the dominant tree species of the temperate forests of the eastern United States

5. Multiflora rose, privet, Asian honey suckle, Bradford pear

These are some of the aggressive species that are crowding out native plants in the eastern United States. They out-compete for resources and provide poor-quality food for species depending on the native plants.

What do conservation biologists who adopt the small-population approach study?

Conservation biologists who adopt the small-population approach study the processes that cause extinctions once population sizes have been severely reduced.

What is an extinction vortex? Use Figure 56.11 to label the processes driving an extinction vortex.

An extinction vortex is when a small population is vulnerable to inbreeding and genetic drift, which can draw the population into a downward spiral. The population continues to shrink and, unless the spiral is reversed, it will become extinct.

In Figure 56.11, the small population will have a loss of genetic variation that can enable evolutionary responses to environmental change, such as the appearance of new strains of pathogens. Both inbreeding and genetic drift can cause a loss of genetic variation and their effects become more harmful as a population shrinks. Inbreeding often reduces fitness because offspring are more likely to be homozygous for harmful recessive traits. As the population continues to spiral downward, lower reproduction rates and higher mortality rates occur until the size of the population becomes so small that extinction will occur.

In conservation biology MVP does not stand for Most Valuable Player. What does it stand for and why is it important?

MVP stands for minimum viable population. This is important because it is the minimal population size at which a species can sustain its numbers and not be vulnerable to start down an extinction vortex

Why is the total number of individuals in a small population not a good measure of its reproductive potential?

The total size of a population may be misleading because only certain members of the population breed successfully and pass their alleles on to offspring. Therefore, a meaningful estimate of minimum viable population requires the researcher to determine the effective population size, which is based on the breeding potential of the population.

What role can a loss of critical habitat play in threatened and endangered populations? Frame your answer using the case study of the red-cockaded woodpecker.

A loss of critical habitat can cause threatened and endangered populations to show a downward trend, even if the population is far above its minimum viable population size. A case study on the decline of the red-cockaded woodpecker can be used as to explain the role of a loss of critical habitat. The red-cockaded woodpecker, an endangered species, is found only in the southeastern United States. These birds require mature pine forests for nesting, preferably ones dominated by the longleaf pine. A critical-habitat factor for the red-cockaded woodpecker is that there must be low undergrowth of plants around the pine trunks. Breeding birds tend to abandon nests when vegetation among the pines is thick and higher than about 4.5 m. Periodic fires in the longleaf pine forests, have maintained the low undergrowth. Nesting for the red-cockaded woodpecker occurs only in ma ture, living pine trees. Small holes are drilled around the entrance to its nest cavities which causes resin from the tree to ooze down the trunk. The resin seems to repel predators, such as corn snakes, that eat bird eggs and nestlings. The red-cockaded woodpecker is on the decline because of the destruction or fragmentation of suitable habitats by logging, fire suppression, urban development and other human activities. The longleaf pine forests have declined by 3% of its original area and the covered area has not increased since 2004. This has been one factor in the decline of the red-cockaded woodpecker species.

What is landscape ecology and why is it important in biodiversity?

Landscape (or seascape) is a mosaic of connected ecosystems. Landscape ecology focuses on the factors controlling exchanges of energy, materials, and organisms across multiple ecosystems. The biodiversity of a given landscape is heavily influenced by its physical features, or structure. Understanding landscape structure is critically important in conservation because many species use more than one kind of ecosystem, and many live on the borders between ecosystems.

Describe how the increase in cowbirds is related to forest fragmentation and the creation of edges.

The brown-headed cowbird (Molothrus ater) is an edge-adapted species that lays its eggs in the nests of other birds, often migratory songbirds. Cowbirds need forests, where they can parasitize the nests of other birds and open fields, where they can forage for insects. Thus, their populations are growing where forests are being cut and fragmented, creating more edge habitat and open land. Increasing cowbird parasitism and habitat loss are correlated with declining populations of several of the cowbird's host species. 16. What are potential positive and negative effects of movement corridors?Movement corridors can promote dispersal and reduce inbreeding in declining populations and are especially important to species that migrate seasonally. However, a corridor can also be harmful—for example, by allowing the spread of disease.

Explain the concept behind a zoned reserve.

A zoned reserve is an extensive region that includes areas relatively undisturbed by humans surrounded by areas that have been changed by human activity and are used for economic gain. The key challenge to the zoned reserve approach is to develop a social and economic climate in the surrounding lands that is compatible with the long-term viability of the protected core.

Why is urban ecology a growing interest among ecologists? Do you know of urban ecology projects in your area?

Urban ecology examines organisms and their environment in urban settings. As cities expand in number and size, protected areas that were once outside city boundaries become incorporated into urban landscapes. Ecologists are now studying cities as ecological laboratories, seeking to balance species preservation and other ecological needs with the needs of people.

How has agriculture affected nitrogen cycling? Explain three negative consequences of nutrient enrichment.

Nitrogen is a main nutrient lost through agriculture. (Figure 55.14). Plowing mixes the soil and speeds up the decomposition of organic matter, releasing nitrogen that is then removed when crops are harvested. Fertilizers containing nitrates and other forms of nitrogen that plants can absorb are used to replace the nitrogen that is lost. However, after crops are harvested, few plants remain to take up nitrates from the soil. As shown in Figure 55.15, without plants to absorb them, nitrates are often leached from the ecosystem.

Three negative consequences of nutrient enrichment concern the use of industrial fer tilizers. When the nitrogenous minerals in the soil exceed the critical load, leaching into the groundwater or run off into freshwater and marine ecosystems, cause contamination of water supplies and cause eutrophication in aquatic ecosystems. The nitrate concentrations in groundwater are increasing in most agricultural regions, sometimes reaching levels that are unsafe for drinking. Many rivers contaminated with nitrates and ammonium from agricultural runoff and sewage drain into the Atlantic Ocean, with the highest impact coming from northern Europe and the central United States. The Mis sissippi River carries nitrogen pollution to the Gulf of Mexico, fueling a phytoplankton bloom each summer. When the phytoplankton die, their decomposition by oxygen-using organisms results in an extensive "dead zone" of low oxygen levels along the coast. When this occurs, fish and other marine animals disappear from some of the most economically important waters in the United States. In lakes, eutrophication can occur. The bloom and subsequent die-off of algae and cyanobacteria and the ensuing depletion of oxygen are similar to what occurs in a marine dead zone. Such conditions threaten the survival of many organisms.

Explain the process of biological magnification. Discuss at least one example.

Accumulated toxins become more concentrated in successive trophic levels of a food web. This phenomenon is referred to as biological magnification and it occurs because the biomass at any given trophic level is produced from a much larger biomass ingested from the level below. For example, biological magnification of PCBs has been found in the food web of the Great Lakes, where the concentration of PCBs in herring gull eggs, at the top of the food web, is nearly 5,000 times that in phytoplankton, at the base of the food web.

What are microplastics? Why is plastic waste a growing concern? (The interview with Chel sea Rochman concerns plastic waste. It is just before Chapter 52 on p 1163 or can be found in Mastering Biology.)

Microplastics are plastic particles less than 5 mm in size. There is growing concern be cause data suggests that plastic waste can persist in the environment for hundreds to thousands of years. Plastic waste can infiltrate every level of the food chain and affect marine life at every level of biological organization. They are even found in foods that humans eat, water we drink, and in dust and air surrounding us.

Use Figure 56.30 to explain the greenhouse effect. At each number on the figure explain what events are occurring.

Carbon dioxide and other greenhouse gases in the atmosphere absorb heat emitted from Earth's surface and then radiate much of that heat back to Earth. The events of this process are as follows:

1. Some of the incoming solar radiation is reflected back to space, but most passes through the atmosphere to reach Earth's surface.

2. Of the radiation that reaches Earth's surface, some is reflected back to space. Much of the rest is absorbed, warming Earth's surface.

3. Some of the energy that warms the surface is then emitted from Earth as heat.

4. Of the heat emitted from Earth, some escapes to space. Much of the rest is absorbed by greenhouse gases and radiated back toward Earth, thereby trapping heat and increasing the temperature of our planet.

What are the primary sources of the great increase in atmospheric carbon dioxide over the past 170 years?

Burning fossil fuels and deforestation are the primary sources of increased concentration of carbon dioxide in the atmosphere.

What two trends can be determined from Figure 56.29 in your text?

As the concentration of carbon dioxide (ppm) has steadily increased since 1958, the average global temperature (oC) has also increased.

Explain why the ecosystems of the far north, particularly northern coniferous forests and taiga, are experiencing the greatest climate change. Frame your response in the context of a positive feedback loop.

Coniferous forests in western North America have been hard hit by a combination of higher temperatures, decreased winter snowfall, and a lengthening of the summer dry period. Since the later half of the 20th century, otherwise healthy forests have experienced a steady increase in the percentage of trees that die each year. Higher temperatures and more frequent droughts also increase the likelihood of fires (see Figure 55.8). In boreal forests of western North America and Russia, fires have burned twice the usual area in recent decades, again leading to widespread tree mortality. Overall, increases in temperature amplifies the likelihood of fires.

How is atmospheric ozone depleted? What are projected effects of this depletion?

The destruction of atmospheric ozone results primarily from the accumulation of chlorofluorocarbons (CFCs), chemicals once used widely in refrigeration and manufacturing. Decreased ozone levels in the stratosphere increase the intensity of UV rays reaching Earth's surface. The consequences of ozone depletion for life on Earth may be severe for plants, animals, and microorganisms. Some scientists expect increases in both lethal and nonlethal forms of skin cancer and in cataracts among humans, as well as unpredictable effects on crops and natural communities.

Explain the concept behind the phrase sustainable development.

Sustainable development is the concept of economic development that meets the needs of people today without limiting the ability of future generations to meet their needs

Climate change is having an effect on all levels of biological organization, from cells to ecosystems. The Make Connections Figure 56.31, p 1280 in your text, makes a compelling case for the disruption caused by global climate change. Use the examples in the figure to explain the effects of climate change at each of the following levels of biological organization.

a. Effects on cells: Temperature affects the rates of enzymatic reactions, and as a result, the rates of DNA replication, cell division, and other key processes in cells are affected by rising temperatures. Global warming has impaired some organism's defense responses and shortened how long it takes for other organisms to mature and reproduce. For example, in the vast coniferous forests of western North America, climate change has reduced the ability of pine trees to defend themselves against attack by the mountain pine beetle (Dendroctonus ponderosae). Pine defenses include specialized resin cells that secrete resin that can entrap and kill mountain pine beetles. Less resin is secreted in trees that are stressed in rising temperatures and drought conditions. When beetles overwhelm a tree's cellular defense, large numbers of beetle offspring tunnel the wood causing extensive damage. Rising temperatures have shortened how long it takes beetles to mature and reproduce, resulting in even more beetles and damage to the coniferous forests.

b. Effects on individual organisms: Global warming has increased the risk of overheating in some species, leading to reduced food intake and reproductive failure. For instance, an American pika (Ochotona princeps) will die if its body temperature rises just 3oC above its resting temperature. With the increased temperatures, American pikas are spending more time in their burrows to escape the heat. Thus, they have less time to forage for food and this will cause mortality rates to increase and birth rates to drop. Some pika populations have dwindled, some to the point of extinction.

c. Effects on populations: Climate change has caused some populations to increase in size, while others have declined. As the climate has changed, some species have adjusted when they grow, reproduce, or migrate- but others have not, causing their populations to face food shortages and reduced survival or productive success. An example is a documented link between rising temperatures and declining populations of caribou (Rangifer tarandus) in the Arctic. Caribou populations migrate north in the spring to give birth and to eat sprouting plants. As a result of climate change, the plants that the caribou rely on have started to emerge earlier in the spring. The caribou have not made similar changes in the timing of when they migrate and give birth. Consequently, the caribou have a shortage of food and offspring production has dropped fourfold.

d. Effects on communities and ecosystems: Climate change has caused hundreds of spe cies to move to new locations, in some cases leading to dramatic changes in ecological communities. Climate change has also altered primary production and nutrient cycling in ecosystems. Rising temperatures have enabled a sea urchin (Centrostephanus rodgersii) to expand their range to the south and invade southern regions along the coast of Australia. Here, high-density kelp communities have been destroyed.