Like the dinosaurs 65 million years ago, humanity now finds itself in the midst of a mass extinction: a global evolutionary convulsion with few parallels in the entire history of life. But unlike the dinosaurs, we are not simply the contemporaries of a mass extinction - we are the reason for it. John Tuxill, Chris Bright (Ref. 1)
Until recently, biodiversity was a subject of purely academic discussions in narrow scientific circles.
But the signing of the Convention on Biological Diversity by more than 190 countries at the Earth Summit in Rio de Janeiro in 1992 put this subject at the top of international environmental agenda and brought a sense of urgency to the issue of biological conservation.
Indeed, the value of biodiversity must never be underestimated.
We completely agree with the following statements:
Biodiversity ... is not only fundamental to the quality of human life. It is essential for human survival. (Ref. 2)
The future of biodiversity signifies the future of humankind. Its pathways to restoration or destruction are for humans to choose. By being cognisant, and by being morally alive, humanity can work to save its own body and soul. (Ref. 3)
Before looking further into the subject of biodiversity loss, let's first try to define the term "biodiversity".
The most common definition of biodiversity agreed upon by many experts in the field is:
Biodiversity is the variety of all life forms including animals & plants that can be found either in just one location, or on the whole planet.
It is also very common to define biodiversity in terms of a number of species present in a particular environment, or in total in the world.
Biodiversity is the variety of plant and animal species present in the natural environment. (Ref. 4)
Biodiversity is the number of species in a given habitat. (Ref. 5)
Because of that, biodiversity is used interchangeably with the term species diversity as well.
Having said that, it is very important to note that the concept of biodiversity is much wider than that.
All in all, biodiversity encompasses three main factors, that is:
As you can see, we also have genetic & ecosystem dimensions alongside the species dimension.
From this perspective, the following formulation of the concept of biodiversity appears to be a good one:
Biodiversity is the variety and variability of living organisms and the ecological patterns of which they are a part. (Ref. 6)
We analyze the species, genetic & ecosystem types of biodiversity in more detail in the section below.
Although species, genetic & ecosystem dimensions can be classified as distinct types of biodiversity, they are closely related and should be analyzed alongside each other.
Species diversity is a measure of variety of all living species in a given habitat.
A general encyclopedic definition of this term usually includes two aspects (Ref. 7):
Species richness is a simple tool that helps us compare several communities in respect of their species' numbers.
While species richness is a straightforward count of identified living species in a certain community, species abundance goes further than that to determine the weighted presence of each species within this community.
Here is a good example in order to describe this idea better:
Two communities may be equally rich in species but differ in relative abundance. For example, each community may contain 5 species and 300 individuals, but in one community all species are equally common (e.g., 60 individuals of each species), while in the second community one species significantly outnumbers the other four. (Ref. 8)
So which community is more species-diverse?
The answer is: The one that is equally rich in species and equal in relative abundance.
In other words, the community with 5 species of 60 individuals each is more species-diverse than the one that has one species significantly outnumbering the other four.
Up to now, only about 1.8 million species have been identified throughout the world. (Ref. 9)
All these species are further categorized into the following kingdoms of living organisms (Ref. 10):
Scientists estimate that the number of species yet to be described ranges from 4 million to 40 million. (Ref. 11)
This lack of complete knowledge about the number of species on Earth makes it harder for us to understand the rates of biodiversity loss & species extinction.
Now let's take a look at another type of biodiversity - genetic diversity.
Genetic diversity defines a number of genetic parameters which are present in a certain species and which determine all possible genetic variations within this species.
While species diversity looks externally at each species as a member of a bio-community, genetic diversity looks internally at the species' chemical composition to understand how good this species potentially is at adapting to changes in its environment.
Yes, that's correct. It is the genetic diversity that determines how well a species will do to protect itself from external dangers, such as bacterial invasions.
For example, a genetically-poor plant is much more likely to be destroyed by a certain type of bacteria than a genetically-rich one.
This is because the bacteria can adapt better to a simpler genetic makeup of the genetically-poor plant than to a more complicated genetic nature of the genetically-rich species.
Genetic and species types of diversity are closely related to each other, and the loss of one may ultimately lead to the loss of the other.
Let's also remember that living organisms don't exist in a vacuum but rather become genetically-rich by being part of their bio-diverse ecosystems.
For the purposes of this article, we offer the following definition of an ecosystem:
An ecosystem is "a terrestrial or aquatic environment whose ecological and biological functions are independent of other systems." (Ref. 12)
Ecosystem diversity usually refers to a variety of such environments found on our planet, including among others the following types (also often referred to as biomes):
Each ecosystem creates a unique living environment for certain kinds of species which may only be found within that specific ecosystem.
In a way, such a macro-ecosystem defines species & genetic diversity of a certain geographical area as it effectively forms the basis of all life of that region.
If some ecosystems start disappearing for one reason or another, this process will inevitably lead to the loss of species & genetic diversity as well.
It is impossible to put an exact number on global extinction rates. But it is possible, and very important indeed, to look at the big picture and understand the trend.
Species extinction is usually treated as one of the most important components of biodiversity loss.
Many experts are worried that the current species extinction rates are much higher than historically recorded (background or natural) ones.
Here is how John Tuxill and Chris Bright describe this:
Species declines and extinctions have always been a natural part of evolution, but there is something disturbingly different about current extinction patterns.
Examinations of the fossil record of marine invertebrates suggest that the natural or "background" rate of extinctions - the rate that has prevailed over millions of years of evolutionary time - claims approximately one to three species per year.
In stark contrast, most estimates of the current situation are that at least 1,000 species are lost a year - an extinction rate 1,000 times the natural rate even with the most conservative assumptions. (Ref. 13)
So what kinds of species are most vulnerable to this threat?
Some estimates suggest that 25% of all mammal species may become extinct in the near future. As many as 50% of primates, 37% of hoofed mammals (ex., rhinos, horses, deer) and 26% of bats and carnivores (ex., bears & raccoons) are currently at high risk of total disappearance.
Although, as of 1996, only about 11% of all identified bird species were officially classified as threatened with extinction, the trend for birds isn't encouraging - more and more of them are clearly in decline throughout the world.
As for the fish, they are not doing better than other species - it has been assessed that 30% of all known fish species are now threatened with extinction as well.
We observe a similar pattern with other species such as reptiles (20% threatened) and amphibians (25% threatened).
So what causes such dramatic rates of potential extinction of different life forms?
Causes of biodiversity loss have become all too apparent and it is really painful to realize that we - the human race - are one major problem as far as biodiversity preservation is concerned.
We covered this topic to a certain degree in our Animal Extinction article, and we also summarize the main points below.
Habitat loss is not only a physical destruction of natural treasures, it is also an egregious violation of animal rights.
We cannot describe it better than the following statements:
Habitat loss is by far the leading factor [of biodiversity loss]: At least three-quarters of all threatened bird species are in trouble because human activities have transformed and fragmented unique habitats. Forests, wetlands, and grasslands have been altered by intensive agriculture, heavy livestock grazing, commercial plantation forestry, and suburban sprawl. ...
[As an example, migratory songbirds] winter in coffee plantations, where coffee bushes have traditionally been grown under a shady canopy of native forest trees. Unfortunately, this habitat is disappearing as plantations intensify and replant with higher-yielding, sun-tolerant coffee varieties that do not require shade. The result is that neotropical migrants must search even harder to find suitable wintering territory. ...
More than 40,000 large dams and hundreds of thousands of smaller barriers plug up the world's rivers, altering water temperatures, sediment loads, seasonal flow patterns, and other river characteristics to which native fish are adapted. Levees disconnect rivers from their floodplains, eliminating backwaters and wetlands that are important fish spawning grounds. Engineering projects alter river inflows, and agricultural and industrial pollution of waterways further reduces fish habitat.
Deforestation is of course a big part of the habitat loss issue since forests are homes to thousands and thousands of animal & plant species.
We single this problem out because rainforests are by far the biggest and most important storages of our planet's natural treasures - learn more about rainforest biodiversity here.
Rainforests are complex ecosystems which sustain numerous relationships of all types of life forms between each other. Losing rainforests means losing this incredible wealth that the nature has endowed us with.
It is interesting to note that while the indigenous peoples were "guardians" of tropical rain forests for many centuries - up to the end of the 19th - beginning of the 20th century, the forest cover didn't show any significant signs of degradation.
But the advent of new technologies, explosions in population numbers and a seemingly insatiable human demand for natural resources have accelerated the process of tropical deforestation and certainly led to high levels of biodiversity loss in different parts of the world.
Excessive exploitation of wildlife by humans is truly a sad reality of our times.
Wild animals, especially those inhabiting rainforests, are exploited for pet trade, bushmeat trade, for their furs and body parts and for biomedical research. Read some more about international wildlife trade here.
Orangutans - among the most endangered animal species on Earth - have fallen victim to such humans actions as well as. Not only is their habitat being consistently destroyed, orangutans are also illegally traded as pets to satisfy the whims of the unaware (or quite simply uncaring) public.
In another shocking example, boa constrictor snakes had been used for both drug and wildlife smuggling when they arrived from Colombia to Miami Airport in 1993 and were found to carry inside them 39 kg of cocaine. All of the snakes subsequently died.
Species which are taken from one habitat and introduced into another (i.e. alien species) often end up exterminating some native species that were present there before.
A very good example of that is an infamous extinction of the dodo - a bird native to the island of Mauritius in the Indian Ocean.
Historians claim that many alien species, ex. dogs, pigs, cats and Macaques, that were introduced to the island by humans, plundered the dodo nests thus causing dodo populations to collapse and ultimately become extinct.
The same may happen to many other native species living in different habitats.
Although effects of environmental pollution on animals have not been measured in as much detail as its effects on humans, we are pretty safe to assume that animals suffer just as much from pollution as the human populations.
For example, fish and other aquatic animals have been severely affected by acid rain during the last decades of the 20th century, although this issue is now mostly under control. (Ref. 16)
While excessive ultraviolet radiation coming through the ozone layer in the upper atmosphere can cause skin cancer in animals, ozone in the lower atmosphere may damage their lung tissues. (Ref. 17)
Extreme pollution cases, as well as slow but steady rates of pollution, may also unfortunately lead to biodiversity loss and animal extinction.
While we attempt to assess the effects of biodiversity loss (with the emphasis on rainforest biodiversity), let's also have a look at the value and benefits that we all derive from biodiversity.
Rainforests - the biggest storages of Earth's biodiversity - are extremely important global climate regulators.
Rainforests act as pollution filters by absorbing carbon dioxide from the atmosphere. Carbon dioxide (CO2) is a powerful air pollutant which contributes to global warming and therefore to the de-stabilisation of climate patterns throughout the world.
By removing carbon dioxide from the atmosphere, rainforests help keep the global climate stable and functioning properly.
But it is exactly a full spectrum of animal & plant diversity within the rainforests which sustains these complex ecosystems and maintains their health.
In other words, rainforest biodiversity is the basis without which the rainforests simply cannot exist.
So what happens when this biodiversity is lost?
Effect of biodiversity loss:
Rainforests become weaker, disintegrate and lose their capacity to absorb carbon dioxide leading to more global warming and other climate change problems.
It is the rainforest biodiversity that provides us with a vast array of foods which have become our true favorites over the last several decades.
We cannot imagine our lives without products such as cacao (used to make chocolate), coffee, tea, bananas, sugar, pineapples, avocados, and the list goes on and on.
Nowadays, consumers in many countries are also offered even more exotic foods originating from rainforests including such popular ones as maca, guarana, lucuma, acai berries and a lot more.
So what happens if this food biodiversity is lost?
Effect of biodiversity loss:
The variety of foods that we consume will be significantly reduced which may ultimately lead to poorer health as well.
We completely agree with the following statement:
"Let the food be your medicine, and medicine be your food"
and the fact that the rainforest foods we mentioned above are full of super nutrients essential for human & animal health.
But we also know that rainforest biodiversity provides us with a huge variety of medicinal / therapeutical plants & herbs which are always there for us to use when our bodies get into a state of disease for one reason or another and require further help from the nature.
Biodiversity is almost a limitless source of such natural remedies and cures.
Until now, we have discovered and studied only a small percentage of these natural treasures, much of it is still unknown.
So what happens if biodiversity - known and unknown - is lost?
Effect of biodiversity loss:
The variety of natural remedies we rely upon will be greatly reduced inevitably leading to poorer health and "ill-being".
Quite simply, we don't have the right to destroy something which is beautiful and has the right for peaceful existence just because it is.
We, the human race, must stop thinking that we own the nature and can use it and abuse it for someone's economic or financial benefits.
We have a moral obligation to leave this world a better place than the one we inherited from our parents and grand-parents, and make it even more beautiful for our children to admire.
In other words, we have an ethical responsibility to preserve the natural beauty of our planet.
So what happens if biodiversity is lost?
Effect of biodiversity loss:
Natural beauty will vanish and future generations may never be in a position to appreciate the nature's wonders.
According to many experts, Genetic Modification of living organisms which has unfortunately been gaining more traction presents a real danger to biodiversity as no one can really predict how genetically-modified species will behave and what sorts of (negative) effects they will have on other, organic (i.e. non-modified) organisms.
Bioprospecting & Biopiracy are some other highly controversial issues.
Some corporations have been accused of stealing knowledge on local biology from native people living in biodiverse regions and then trying to patent such "discoveries" as their own it - all in the name of more profits. Consequent over-exploitation of such "patented" resources can also lead to biodiversity loss.
Some authors have recently coined a new term - Geodiversity - to draw our attention to the fact that purely geological factors, ex. soil, fossils, minerals and landforms, play a very important role in biodiversity conservation in general.
They define geodiversity as: (Ref. 18)
"The natural range (diversity) of geological (rocks, minerals, fossils), geomorphological (landforms, processes) and soil features. It includes their assemblages, relationships, properties, interpretations and systems."
"The link between people, landscapes and culture; it is the variety of geological environments, phenomena and processes that make those landscapes, rocks, minerals, fossils and soils that provide the framework for life on Earth."
So it becomes clear that "without the variation in topography, physical processes and geological materials, there would be much less biodiversity" (ref. 19) and that geodiversity degradation can ultimately lead to biodiversity loss as well.
We would like to finish off by quoting two renowned authors - John Tuxill and Chris Bright - and their take on the importance of biodiversity to us all:
The loss of species touches everyone, for no matter where or how we live, biodiversity is the basis for our existence.
Earth's endowment of species provides humanity with food, fiber, and many other products and "natural services" for which there is simply no substitute.
Biodiversity underpins our health-care systems: One-fourth of drugs prescribed in the United States include chemical compounds derived from wild organisms, and billions of people worldwide rely on plant- and animal-based traditional medicine for their primary health care.
Biodiversity also supplies a wealth of genes essential for maintaining the vigor of our crops and livestock.
It provides pollination services, mostly in the form of insects, without which we could not feed ourselves.
Frogs, fish, and birds control pests; mussels and other aquatic organisms cleanse our water supplies; plants and microorganisms create our soils.
But these essential natural goods and services constitute a minor part of the picture.
Most of what we are losing is still a mystery to us.
As the noted Harvard University biologist Edward O. Wilson puts it, we live on an unexplored planet. We have barely begun to decipher the intricate ecological mechanisms that keep natural communities running smoothly.
We do not know - even to a rough order of magnitude - how many species there are on earth.
|Written by:||Irina Gray of Tropical-Rainforest-Animals.com|
|Publication Date:||April 2012|
© Irina Gray & Tropical-Rainforest-Animals.com