Conservation

Reasons for extinction

Extinction is when a species comes to an end or dies out

Extinction is a natural biological process that happens on planet Earth and studies of fossils and ancient DNA have shown that million of species have gone extinct in the past

Mass extinction events have also occurred in the past where a very large number of species went extinct at one time

The rate of extinction during these periods are very high

Past mass extinctions were likely caused by major and sudden shifts in the environment such as an Ice Age or an asteroid hitting the Earth

Scientists have been studying the current rates of extinction in recent years and many believe that the Earth is undergoing a current mass extinction with humans being the main cause

Possible reasons for extinction include:

• Climate change

• Competition

• Hunting by humans

• Degradation and loss of habitats

Climate change

The large scale burning of fossil fuels by humans in recent years has led to a large increase in the levels of carbon dioxide in the atmosphere, creating the greenhouse effect

The increased carbon dioxide concentration in the atmosphere has had several knock-on effects on ecosystems around the world

There has been an increase in the mean global temperature

Sea levels are rising

Ocean temperatures and acidity are rising

Ice caps are melting

These knock-on effects have massively changed the habitats of some species, so much so that some are no longer able to survive in the new environmental conditions

For example, polar bears are struggling to survive as more of their habitat melts away earlier each year. The earlier melting of the ice caps means they have to swim further to reach seal populations that they hunt for food

Competition

When there is a limited supply of resources within an area competition between individuals for the same resource can occur

The resources could be food, water, habitat and reproductive mates

Competition can exist within species and between species

Competition reduces the population size of a species

For example, millions of years ago there were many different species of wild dog that lived in North America

When several cat species spread from Asia into North America there were high levels of competition between these carnivores

As a result, there are only nine species of wild dog that exist in North America today

Competition with humans has become a major problem for some species in the last 100 years as humans have taken their food, water and habitat

Introduction of species

When humans colonised new land they would often exchange animal and plant species between their home country and the new land

These introduced species are non-native

Non-native species can be highly problematic as they often have no natural competitors, predators or pathogens that help limit population growth

Without these natural population checks, non-native species can massively increase in number

The large numbers of non-native species can negatively affect the native species through factors such as competition and disease

Grey squirrels have led to the decimation of the red squirrel population in the UK

Grey squirrels were introduced to the UK in 1876

They quickly grew in numbers

The larger grey squirrels compete with red squirrels for food

They also carry and transmit a disease known as squirrelpox which is fatal to red squirrels

Hunting by humans

In the past humans would have hunted, killed and eaten wild animal species in order to survive

Nowadays most of the meat that humans consume comes from domesticated livestock like cattle, sheep and chicken

The evolution of livestock has negated the need for many humans to hunt wild animals

Some humans in underdeveloped countries still have to hunt animals for survival

The hunting of wild animals is still common and has become a sport for some individuals

The rarer and more vulnerable species are often more desirable for a sport hunter

If too many individuals within a species are killed then the population can become so small that it is no longer able to survive

Degradation and loss of habitats

This is the main cause of species extinction

Over recent years humans have aggressively destroyed animal habitats by cutting down forests, draining wetlands and polluting the water, soil and air

This is highly problematic because species are adapted to survive within their specific habitat, under particular environmental conditions

Without their habitat, organisms will not get the resources they need to survive

When their habitat area becomes reduced, a species will:

Search for other suitable habitats

Compete with others for the remaining habitats

Eventually, the range of a habitat can become so small or non-existent that a species is not able to survive and goes extinct

Examiner Tips and Tricks

All of the factors above explain how the population of a species can dramatically decrease and become very small. It is worth thinking about why small populations are so much more vulnerable to extinction. Several things are happening at the genetic level. A smaller population has increased levels of inbreeding, which reduces the genetic variation in the population. Genetic drift has a larger impact on a small population leading to an even further decrease in genetic variation. As we know from natural selection genetic variation is important as it allows a species to adapt and survive environmental change; it improves its fitness. So a small population has a lower fitness meaning increased mortality and decreased reproduction.

Reasons for maintaining biodiversity

Biodiversity is the range and variety of genes, species and habitats within a particular region

It is made up of three components:

• Genetic diversity

• Species diversity

• Ecosystem diversity

Global biodiversity has a major impact on humans and all other species on the planet

There are many reasons for maintaining biodiversity:

• Ecological

• Economic

• Aesthetic

• Social

• Moral/ethical

• Environmental

• Agricultural

Ecological reasons

Biodiversity has a major effect on the stability of an ecosystem

A more diverse ecosystem is better able to survive and adapt to environmental changes or threats

For example, if the temperature of a species rich lake rises due to global warming:

Some species of fish in the ecosystem are unable to cope with the change while others can

The fish that are able to cope will survive, reproduce and keep contributing to the ecosystem

Within communities there are keystone species that have a larger impact on the ecosystem than others

When these species are lost there are several consequences

Bush elephants in the African savannah is a keystone species

They graze in a very extreme way, knocking over and eating several species of tree

This destruction of vegetation actually helps to maintain the ecosystem

Elephant dung also provides a habitat for many important fungi and insect species

When elephants were legally hunted for their ivory in large numbers, their populations reduced and scientists observed a major negative impact on the savannah

Economic reasons

Ecosystems have a high economic value

Many of the medicines used today have originated from plants, fungi and bacteria

For example the cancer fighting drug paclitaxel is sourced from Pacific and Himalayan yew trees

The Himalayan Yew has declined in numbers due to over harvesting for fuel and medicine

Due to the large number of drugs that have already been sourced from Nature it is reasonable to assume that there are other drugs, yet to be found in Nature, that could be used in the future

Ecotourism a major source of income for many countries

Many tourists travel to and spend money in National Parks so they can see wildlife

Increased tourism in a country contributes to the economy and provides jobs

Ecosystems have also made major contributions to the field of science and technology

The specific enzyme used in DNA sequencing was first discovered in thermophilic bacterium found in a hot spring in Yellowstone National Park, USA

Aesthetic reasons

Humans find great joy and pleasure in the beauty of Nature

It provides inspiration for creatives such as photographers, writers, musicians and artists

There is a strong argument for preserving biodiversity because of its aesthetic benefits

Social reasons

Many people enjoy spending time in the natural environment

There are many activities that people can do together in nature, eg. birdwatching, walking, climbing

Such environments may be lost if they are not conserved, with the loss of the social benefits that they can bring

Moral and ethical reasons

Many people believe that humans have a moral obligation to prevent the loss of biodiversity that results from human activities

Humans share the planet with millions of others species and they have no right to cause the extinction of other species

As humans are the most intelligent species on the planet the responsibility falls upon their shoulders to protect and value all of the organisms on the planet

Environmental reasons

Humans need diverse ecosystems because of the essential environmental services they provide

Plants absorb carbon dioxide from the atmosphere and help to reduce the greenhouse effect and climate change

Microorganisms digest and break down the masses of organic waste that are produced by larger organisms

Humans have irrigation and drinking water thanks to the transpiration of plants and their contribution to the water cycle

Different fungi and bacteria species are a major part of the nutrient cycle that allows for nutrients to reenter the soil for further plant growth

Plants are producers in food webs; they are both a direct and indirect energy source for humans through fruit, vegetables and meat

Agricultural reasons

Most of the crops that humans grow are very uniform with low genetic diversity

The wild relatives of crops can provide a source of genetic diversity to rescue crops that are affected by disease or other disasters

Many of the wild relative species are under threat due to habitat destruction and climate change

All of the world's potato crop comes from a single species (Solanum tuberosum)

This lack of species diversity makes the crop highly susceptible to disease

There are over 100 species of wild potato that grow in the Andes

These Andean species act as a source of alleles for disease resistance

These alleles have been introduced to the potato crop through gene technology and interbreeding

Methods of conservation

An endangered species is a species that is being threatened with extinction

Conservation of endangered species can be approached in several different ways

Ideally a species should be kept in their natural habitat as all the support systems they need to maintain life already exist there

National parks and marine parks are examples of conservation methods that do this

When it is not possible to do this endangered species can be captured and placed in captivity for conservation efforts

Zoos and botanical gardens take part in conservation programmes

Scientists have also come up with several methods to try and ensure the long-term survival of endangered species through frozen zoos and seed banks

Conserved areas

National parks are areas within countries where the wildlife and environment are protected

Governments control these areas and pass legislation to ensure their protection

There are several restrictions

Humans access is strictly controlled

Industrial activities such as agriculture and building are tightly regulated

Hunting is limited or completely prohibited

Marine parks are protected areas of water that have been set up for the conservation of endangered marine ecosystems and species

They also have restrictions to prevent overfishing and pollution

Public engagement with conservation efforts is important for long term success:

National and Marine parks can attract thousands of tourists each year which provides money and increases awareness of the conservation effort

Involving members of the local community in the management of protected areas can provide jobs and increase acceptance of the parks

Some of the profits made from parks can be used to improve the health and education standards in the nearby communities to illustrate the benefits of having such areas nearby

Conservation in captivity

Zoos can also contribute towards the conservation of endangered animal species

Captive breeding programmes can breed individuals of a species so their offspring can be released into the wild

Zoos are an invaluable resource for scientific research

Scientists are able to closely study animal’s genetics, behaviours and habitat needs

There are some problems with zoos and their role in conservation:

Captive breeding of small species populations can reduce genetic diversity

Certain animal species will not breed in captivity

Not all zoos can provide adequate habitats for animals with specific needs

There are stories of both success and failure when it comes to zoos and conservation:

The oryx is an antelope-like species that was saved from extinction and reintroduced into the wild in Africa thanks to zoos and captive breeding programmes

Pandas have been in captive breeding programs for over 60 years and not a single panda has been reintroduced into the wild

Botanic gardens are the plant equivalent of zoos

They use cuttings and seeds collected from the wild to establish a population of the endangered species in captivity

Methods of tissue culturing and cloning can also be used to obtain large numbers of plants from a small sample size

The captive population can be used in the future for reintroduction into habitats where they have become rare

Research is a major role of botanic gardens

They investigate reproduction and growth in different plant species so that they can be grown in captivity

If the plants original habitat no longer exists they try to find suitable new habitats

Both zoos and botanic gardens are instrumental to education

They help to raise awareness of vulnerable, endangered species and conservation efforts worldwide

Storing genetic material for Conservatio

If a species becomes extinnct in the wild then traditional conservation methods are no longer useful

New technology has provided ways of storing the genetic material of endangered species so that it is not lost forever

Frozen zoos store genetic material from animals (eggs, sperm, tissue samples etc) at very low temperatures so that they can be kept for a very long time

Ideally samples are collected from different individuals of the same species to maintain the gene pool

The temperature used is roughly -196oC

A large amount of genetic material can be stored in a relatively small space

In the future genetic materials from extinct animal species could be used to breed and reintroduce a species through IVF and genetic engineering

The San Diego Zoo in the USA has frozen zoo facilities

A seed bank is a facility that conserves plant diversity by drying and storing seeds in a temperature controlled environment

Usually, seeds of the same species are collected from different sites to maintain the gene pool

If the plant species goes extinct then the seeds can be used to grow them again

Seeds can only be stored for so long. After a certain period of time the stored seeds are grown into plants and fresh seeds for storage are taken from those plants

The Svalbard Global Seed Vault in Norway has almost 1 million species of plant seed. It is located in the Arctic Circle with ideal environmental conditions

Many organisations send seeds from crop plants to be stored there for safekeeping

Some plants have seeds that can not be frozen such as coffee and cocoa plants

In order to preserve the genetic diversity of these plants successive generations must be grown or tissue cultures taken

Examiner Tips and Tricks

Remember all of the conservation efforts made to stop a species going extinct is pointless if they don't have a natural habitat to return to. Conserving whole ecosystems is essential for the long term survival of species.

Areas like tropical rainforests and coral reefs have exceptional biodiversity but they are currently under threat from industrial development, pollution and exploitation.

Assisted reproduction

Endangered mammals tend to have small and isolated populations

Small populations are prone to inbreeding and inbreeding depression

Inbreeding depression is the reduction in fitness of a population due to breeding between closely related individuals and the resulting increased homozygosity

When populations are isolated it can also be difficult for individuals to find suitable reproductive mates

Previously large mammals were transported between zoos in captive breeding programs

Advantage: Humans were able to monitor the health of the mother and foetus

Disadvantage: It was highly expensive and unreliable as sometimes individuals would refuse to mate

Science has come up with several solutions for inbreeding and the lack of reproductive mates in endangered mammals

IVF

In vitro fertilisation involves the fertilisation of an egg outside of the female body

For example in a test tube or petri dish

Method:

A needle is inserted into the female’s ovaries and eggs are extracted

The eggs are kept in a culture medium for a short amount of time

Male semen is mixed with the eggs so fertilisation can occur

Several zygotes form and develop into embryos

The embryos are placed in a culture for several days

The embryos are transferred either into the mother, or another female

IVF is advantageous over natural mating because it allows humans to control and confirm fertilisation of the embryo

Embryo transfer

Pregnancies are high risk for females; complications can arise which in some cases prove fatal

Since the population numbers of an endangered species are already very low each reproductive female is of very high value and importance

Embryo transfer can be used to avoid the risks of pregnancy for the vulnerable female so that she can provide many eggs for multiple offspring

Method:

An egg belonging to a female of the vulnerable species is fertilised by the sperm belonging to a male of the same species

A zygote forms which develops into an embryo

After fertilization, the embryo is taken from the uterus of the female and transferred to a surrogate female

The embryo develops to full term and the offspring is born

The surrogate mother can be from another non-vulnerable species

This technique has been used to try and conserve populations of several different species of African antelope

Surrogacy

A surrogate is any female that becomes pregnant with the embryo from another female and carries the embryo to full term

Surrogate mothers require hormone treatment before they receive an embryo

The hormones ensure that her uterus is in the right condition for the embryo to embed

There are multiple ways in which the embryo might have been conceived:

Naturally

Artificial insemination (semen from the male is injected into the uterus of the female)

IVF

A surrogate female can be the same or different species to the biological mother of the embryo

If it is a different species it needs to be closely related to ensure compatibility of the embryo and uterus

Examiner Tips and Tricks

IVF is most commonly discussed as a human technique for treating infertility. However, make sure to recognise its importance in conservation of endangered (non-human) species.

Controlling invasive species

A species that has moved into an ecosystem where it was previously unknown is an invasive species

An invasive species can occur naturally as a result of a species migrating or expanding their habitat but most recorded incidents of invasive species have been caused by humans

In the past humans have:

Knowingly collected and traded species between countries via ships

Unknowingly provided transport for invasive species to a new ecosystem

Introduced alien species deliberately as biological control for pests

Problems with invasive alien species

The biological process of evolution often brings balance to an ecosystem

Through evolution the environment a species lives in strongly influences the adaptations that the species evolve to live in that environment

A non-native invasive species will have evolved adaptations for survival in different environmental conditions so when they are introduced into the new ecosystem this can upset the balance

In a new ecosystem invasive species will have few or none of the natural population controls that existed in their previous ecosystem:

They will have no natural predators or competitors

As a result they are able to increase in number at a rapid rate

This can affect the processes within an ecosystem

Competition may occur between invasive species and native species that occupy a similar niche with the native species getting displaced or pushed to extinction. It could be competition for things such as prey, soil nutrients, light and space

Many invasive species can be over successful predators causing a massive decline in their prey species

Invasive species can introduce new diseases, to which the native species have no natural immunity

The biodiversity of an ecosystem is impacted which reduces its productivity

Humans can also feel the knock-on effects of an invasive species taking over an ecosystem

The spread of novel diseases and irritants of the skin / breathing system directly affect human health

The economy of a country can be severely impacted by the costs of trying to control invasive species and their negative effects

In the past travel has been brought to a standstill by invasive species, with some plant species prone to blocking up waterways

Role of IUCN & CITES in conservation

International cooperation is essential if conservation is to be successful

There are several agreements and authorities that exist within and between countries with the aim of protecting and conserving species worldwide

IUCN

The International Union for the Conservation of Nature (IUCN) is described as “The global authority on the status of the natural world and the measures needed to safeguard it”

One of the duties that the IUCN carries out is assessing the conservation status of animal and plant species around the world

The IUCN has its own classification system

There are several different categories and levels that a species can fall into depending on their population numbers and the threats and risks to those populations

Scientists use data and modelling to estimate which category each species should be in

Animals that are on the IUCN Red List of Threatened Species™ can be seen online as this list is made public

Flowchart of IUCN species assessment: All species split into 'Assessed' and 'Not Assessed'. Assessed divides into 'Sufficient' or 'Insufficient Data', leading to threat levels.

The IUCN classification system of species—scientists are continually updating and reviewing the conservation status of species

CITES

The Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) is a global agreement that has been signed by over 150 countries

Its aim is to control the trade of endangered species and their associated products

For example, elephants and their ivory tusks

CITES categorises endangered and vulnerable species into three appendices:

Appendix I : species that are endangered and face the greatest risk of extinction (for example, the red panda)

Appendix II: species that are not currently endangered or facing extinction, but will be unless trade is closely controlled (for example, the venus fly trap)

Appendix III: species included at request of the country that is regulating trade of the species and trying to prevent its overexploitation (for example, the two-toed sloth in Costa Rica)

There are different trading regulations that apply to each appendix:

For species in appendix I: all trade in the species and their associated products is banned

For species in appendix II: trade is only granted if an export permit has been issued by the involved countries

For species in appendix III: permits are required for regulated trade. Permits are easier to come by for species in this appendix

Scientists are continuously adding new species and reviewing the status of species already in the database

There are several concerns about the efficacy of CITES listings

When the trade of a certain endangered species becomes illegal, its price increases

The increased economic value of the species can be a major incentive for people to break the law