Understandings:
● An indicator species is an organism used to assess a specific environmental condition.
● Relative numbers of indicator species can be used to calculate the value of a biotic index.
● In situ conservation may require active management of nature reserves or national parks.
● Ex situ conservation is the preservation of species outside their natural habitats.
● Biogeographic factors affect species diversity.
● Richness and evenness are components of biodiversity.
Applications and skills:
● Application: Case study of the captive breeding and reintroduction of an endangered animal species.
● Application: Analysis of the impact of biogeographic factors on diversity limited to island size and edge effects.
● Skill: Analysis of the biodiversity of two local communities using Simpson’s reciprocal index of diversity.
Guidance:
● The formula for Simpson’s reciprocal index of diversity is: D = N(N – 1)/∑ n(n – 1)
In an ecosystem, some species are very sensitive to environmental change. They are called indicator species.
Some indicator species: A common indicator species is lichen. Lichens live on rocks and trees and are a reliable indicator of air quality. They are very sensitive to pollution in the atmosphere. Lichens are not usually found on trees in a city because the air is too polluted for them. Because lichens also retain metal in their tissues, they can show the presence of lead or mercury in the air.
Freshwater indicator species have various levels of pollution tolerance. Organisms like leeches and aquatic worms are not very sensitive and can live in water with low oxygen levels and high amounts of organic matter. Organisms like the larvae of alderfly and damselfly are moderately sensitive, whereas the larvae of the mayfly and caddisfly are very sensitive to pollution. The very sensitive organisms must have high levels of oxygen and little organic matter in the water in order to survive. The cleaner the water, the higher the number of sensitive organisms present.
Biotic index
When you perform a river or stream study,
you count the number of macroinvertebrates collected in each sample and record the data on a stream study form. The number of organisms in each group is multiplied by a factor that is determined by how sensitive the organism is to pollution. The presence of sensitive organisms is multiplied by a higher number. The more sensitive organisms you have in the sample, the higher the quality of the water in the river or stream. The total number is called the biotic index.
Richness and evenness are components of biodiversity
Biological diversity can be described in two ways: evenness and richness. The number of different organisms in a particular area is the richness. Evenness is how the quantity of each organism compares with the other. Richness only takes into account the kinds of species present in the ecosystem, while evenness take abundance into account.
Analysis of the biodiversity of two local communities
A measure that takes into account both richness and evenness is the Simpson diversity index.
To calculate the Simpson diversity index, we need the formula:
D = N(N – 1)/sum of n(n – 1)
where
D = diversity index
N = total number of organisms in the ecosystem n = number of individuals of each species
So, for each community we need to know the number of organisms present and the number of individuals of each species present. This information is found by sampling the two areas with quadrats as follows:
• record the number of plant species in each quadrat
• count the number of individuals of each species
• record the data for each area in tables.
Management of conservation areas
In order to keep the beauty and diversity of a nature reserve, it is important to manage it effectively. Nature reserves cannot just be left to nature. Active intervention is required to restore areas and protect native species. There are several methods that can be implied in order to conserve areas:
- Restoration
Restoration attempts to return the land to its natural state. To restore land on which vegetation has been destroyed may require managers to use active management techniques such as scrub clearance, cutting or burning, and replanting.
- Recovery of threatened species
Threatened species are usually helped when we restore their habitat. Active management maintains the areas needed for the habitat of the endangered species. In a Florida nature reserve, the habitat of the endangered gopher tortoise is being restored. This tortoise lives in deep burrows in a sandhill ecosystem. As many as 350 other animal species live in the burrow with the gopher tortoise. Restoration of the sandhill ecosystem is necessary for the existence of all these species, not just the gopher tortoise.
- Removal of introduced species
Most of the alien species (species that are not native to an area when it is introduced) that are introduced into an area die out because they do not have adaptations for the local ecosystem. However, when an exotic species can survive and takes over, it can have devastating results.
- Legal protection against development or pollution
Nature reserves protected by the government or private organizations can prohibit activities that might harm the native animals and plants. Such activities might be extraction of minerals, development of recreational facilities, hunting of animals, or over-use by the public. Active management measures include posting warning signs and using security personnel to ensure the nature reserve is protected from harmful human activities.
- Funding and prioritizing
Increasing public awareness of reserves can help provide the funds needed to support the reserves. Management of nature reserves requires a balance between the health of the ecosystem, maintenance of diversity, and the costs involved.
In situ conservation methods
Nature reserves help endangered species by maintaining their habitat and preventing competition from invasive species. Keeping these organisms in situ means putting them in the ecosystem where they belong. Organisms have adapted over hundreds of years to a certain set of conditions. These conditions include the other species present in the ecosystem as well as abiotic factors. It is the goal of in situ conservation to allow the target species to continue to adapt to conditions in the reserve without interference from outside influences, such as invasive species and human incursions.
Reserves can be terrestrial (land-based) and aquatic (water-based). Terrestrial reserves can be found in most communities. Lake and pond areas are also common.
In situ conservation aims to achieve the following:
On occasion, the in situ area is unable to protect the targeted species. For example:
Ex situ conservation methods
Ex situ methods are usually used as a last resort. If a species cannot be kept in its natural habitat safely, or the population is so small that the species is in danger of extinction, then ex situ methods of conservation are used. There are three methods: captive breeding of animals, cultivation of plants in botanic gardens, and storage of seeds in seed banks
1. Captive breeding: The goal of captive breeding is to try to increase the reproductive output of a species and ensure survival of the offspring. Here are some of the techniques used:
- Artificial insemination. If the animals are reluctant to mate, semen is taken from the male and placed into the body of the female.
- Cryogenics. Eggs, sperm cells, and embryos can be frozen for future use.
-Human-raised young. If a mother is not interested or able to care for her young, then staff can hand-raise the young in the nursery of the zoo.
One problem with captive-breeding programs is that the introduction into the wild of captive-bred individuals can spread disease to a non-infected wild population. When some captive-bred desert tortoises were introduced to their native habitat, they infected the wild population with a respiratory disease. Another problem is that animals bred in captivity have not experienced the process of in situ learning that their wild relatives undergo. This may put them at a severe disadvantage in the wild.
2. Botanical gardens
Plants are easily kept in captivity. They have simple needs and usually breeding them is not difficult. About 80 000 plant species are grown in private gardens, arboretums, and botanical gardens all over the world. It is much easier to take care of and breed plants outside their natural setting than it is to take care of and breed animals. One problem with the collections of botanical gardens, however, is that the wild relatives of commercial crops are underrepresented. These plants may have genes that confer resistance to diseases and pests. Adding these wild plant relatives to collections at botanical gardens would provide gene banks for commercial crops.
3. Seed banks
Seeds in a seed bank are kept in cold, dark conditions. Under these conditions, the metabolism of the seed slows down and prevents it from germinating. Seed can be kept this way for decades. Some seeds are grown, allowed to mature, and their new seed collected. Currently, seeds from 10 000 to 20 000 plant species from all over the world are stored in seed banks.
The impact of edge effect on diversity
Edge effect describes what occurs at habitat boundaries where two bordering communities influence each other. Factors that affect the edge can be:
• abiotic, such as more or less sunlight or moisture at the edge of a forest
• biotic, such as the presence of certain predators at the edge.
Some species thrive only at the edges of a habitat because they depend on unique resources that are not present in the interior environment of the habitat. Other species thrive only in the interior environment. High habitat diversity, which includes both the interior and the edge of a habitat, promotes species richness in an ecosystem.
Edge effect plays an important role in the habitat suitability of the western meadowlark and other grassland birds. A study of how the edge effect affects the presence of the western meadowlark provided evidence that species diversity could be increased in
the ecosystem if woody plant encroachment was curtailed so that populations of grassland bird species that live at the edge of the woodland could be maintained. A consistent decline in grassland bird populations because of woody plant encroachment decreases species diversity.
● An indicator species is an organism used to assess a specific environmental condition.
● Relative numbers of indicator species can be used to calculate the value of a biotic index.
● In situ conservation may require active management of nature reserves or national parks.
● Ex situ conservation is the preservation of species outside their natural habitats.
● Biogeographic factors affect species diversity.
● Richness and evenness are components of biodiversity.
Applications and skills:
● Application: Case study of the captive breeding and reintroduction of an endangered animal species.
● Application: Analysis of the impact of biogeographic factors on diversity limited to island size and edge effects.
● Skill: Analysis of the biodiversity of two local communities using Simpson’s reciprocal index of diversity.
Guidance:
● The formula for Simpson’s reciprocal index of diversity is: D = N(N – 1)/∑ n(n – 1)
- D = diversity index, N = total number of organisms of all species found, and n = number of individuals of a particular species.
In an ecosystem, some species are very sensitive to environmental change. They are called indicator species.
Some indicator species: A common indicator species is lichen. Lichens live on rocks and trees and are a reliable indicator of air quality. They are very sensitive to pollution in the atmosphere. Lichens are not usually found on trees in a city because the air is too polluted for them. Because lichens also retain metal in their tissues, they can show the presence of lead or mercury in the air.
Freshwater indicator species have various levels of pollution tolerance. Organisms like leeches and aquatic worms are not very sensitive and can live in water with low oxygen levels and high amounts of organic matter. Organisms like the larvae of alderfly and damselfly are moderately sensitive, whereas the larvae of the mayfly and caddisfly are very sensitive to pollution. The very sensitive organisms must have high levels of oxygen and little organic matter in the water in order to survive. The cleaner the water, the higher the number of sensitive organisms present.
Biotic index
When you perform a river or stream study,
you count the number of macroinvertebrates collected in each sample and record the data on a stream study form. The number of organisms in each group is multiplied by a factor that is determined by how sensitive the organism is to pollution. The presence of sensitive organisms is multiplied by a higher number. The more sensitive organisms you have in the sample, the higher the quality of the water in the river or stream. The total number is called the biotic index.
Richness and evenness are components of biodiversity
Biological diversity can be described in two ways: evenness and richness. The number of different organisms in a particular area is the richness. Evenness is how the quantity of each organism compares with the other. Richness only takes into account the kinds of species present in the ecosystem, while evenness take abundance into account.
Analysis of the biodiversity of two local communities
A measure that takes into account both richness and evenness is the Simpson diversity index.
To calculate the Simpson diversity index, we need the formula:
D = N(N – 1)/sum of n(n – 1)
where
D = diversity index
N = total number of organisms in the ecosystem n = number of individuals of each species
So, for each community we need to know the number of organisms present and the number of individuals of each species present. This information is found by sampling the two areas with quadrats as follows:
• record the number of plant species in each quadrat
• count the number of individuals of each species
• record the data for each area in tables.
Management of conservation areas
In order to keep the beauty and diversity of a nature reserve, it is important to manage it effectively. Nature reserves cannot just be left to nature. Active intervention is required to restore areas and protect native species. There are several methods that can be implied in order to conserve areas:
- Restoration
Restoration attempts to return the land to its natural state. To restore land on which vegetation has been destroyed may require managers to use active management techniques such as scrub clearance, cutting or burning, and replanting.
- Recovery of threatened species
Threatened species are usually helped when we restore their habitat. Active management maintains the areas needed for the habitat of the endangered species. In a Florida nature reserve, the habitat of the endangered gopher tortoise is being restored. This tortoise lives in deep burrows in a sandhill ecosystem. As many as 350 other animal species live in the burrow with the gopher tortoise. Restoration of the sandhill ecosystem is necessary for the existence of all these species, not just the gopher tortoise.
- Removal of introduced species
Most of the alien species (species that are not native to an area when it is introduced) that are introduced into an area die out because they do not have adaptations for the local ecosystem. However, when an exotic species can survive and takes over, it can have devastating results.
- Legal protection against development or pollution
Nature reserves protected by the government or private organizations can prohibit activities that might harm the native animals and plants. Such activities might be extraction of minerals, development of recreational facilities, hunting of animals, or over-use by the public. Active management measures include posting warning signs and using security personnel to ensure the nature reserve is protected from harmful human activities.
- Funding and prioritizing
Increasing public awareness of reserves can help provide the funds needed to support the reserves. Management of nature reserves requires a balance between the health of the ecosystem, maintenance of diversity, and the costs involved.
In situ conservation methods
Nature reserves help endangered species by maintaining their habitat and preventing competition from invasive species. Keeping these organisms in situ means putting them in the ecosystem where they belong. Organisms have adapted over hundreds of years to a certain set of conditions. These conditions include the other species present in the ecosystem as well as abiotic factors. It is the goal of in situ conservation to allow the target species to continue to adapt to conditions in the reserve without interference from outside influences, such as invasive species and human incursions.
Reserves can be terrestrial (land-based) and aquatic (water-based). Terrestrial reserves can be found in most communities. Lake and pond areas are also common.
In situ conservation aims to achieve the following:
- protect the target species by maintaining the habitat
- defend the target species from predators
- remove invasive species
- have a large enough area in the reserve to maintain a large population
- have a large enough population of the target species to maintain
genetic diversity.
On occasion, the in situ area is unable to protect the targeted species. For example:
- the species is so endangered that it needs more protection
- the population is not large enough to maintain genetic diversity
- destructive forces cannot be controlled, such as invasive species, human incursion, and natural disasters
Ex situ conservation methods
Ex situ methods are usually used as a last resort. If a species cannot be kept in its natural habitat safely, or the population is so small that the species is in danger of extinction, then ex situ methods of conservation are used. There are three methods: captive breeding of animals, cultivation of plants in botanic gardens, and storage of seeds in seed banks
1. Captive breeding: The goal of captive breeding is to try to increase the reproductive output of a species and ensure survival of the offspring. Here are some of the techniques used:
- Artificial insemination. If the animals are reluctant to mate, semen is taken from the male and placed into the body of the female.
- Cryogenics. Eggs, sperm cells, and embryos can be frozen for future use.
-Human-raised young. If a mother is not interested or able to care for her young, then staff can hand-raise the young in the nursery of the zoo.
One problem with captive-breeding programs is that the introduction into the wild of captive-bred individuals can spread disease to a non-infected wild population. When some captive-bred desert tortoises were introduced to their native habitat, they infected the wild population with a respiratory disease. Another problem is that animals bred in captivity have not experienced the process of in situ learning that their wild relatives undergo. This may put them at a severe disadvantage in the wild.
2. Botanical gardens
Plants are easily kept in captivity. They have simple needs and usually breeding them is not difficult. About 80 000 plant species are grown in private gardens, arboretums, and botanical gardens all over the world. It is much easier to take care of and breed plants outside their natural setting than it is to take care of and breed animals. One problem with the collections of botanical gardens, however, is that the wild relatives of commercial crops are underrepresented. These plants may have genes that confer resistance to diseases and pests. Adding these wild plant relatives to collections at botanical gardens would provide gene banks for commercial crops.
3. Seed banks
Seeds in a seed bank are kept in cold, dark conditions. Under these conditions, the metabolism of the seed slows down and prevents it from germinating. Seed can be kept this way for decades. Some seeds are grown, allowed to mature, and their new seed collected. Currently, seeds from 10 000 to 20 000 plant species from all over the world are stored in seed banks.
The impact of edge effect on diversity
Edge effect describes what occurs at habitat boundaries where two bordering communities influence each other. Factors that affect the edge can be:
• abiotic, such as more or less sunlight or moisture at the edge of a forest
• biotic, such as the presence of certain predators at the edge.
Some species thrive only at the edges of a habitat because they depend on unique resources that are not present in the interior environment of the habitat. Other species thrive only in the interior environment. High habitat diversity, which includes both the interior and the edge of a habitat, promotes species richness in an ecosystem.
Edge effect plays an important role in the habitat suitability of the western meadowlark and other grassland birds. A study of how the edge effect affects the presence of the western meadowlark provided evidence that species diversity could be increased in
the ecosystem if woody plant encroachment was curtailed so that populations of grassland bird species that live at the edge of the woodland could be maintained. A consistent decline in grassland bird populations because of woody plant encroachment decreases species diversity.