“The earth is our home. Unless we preserve the rest of life, as a sacred duty, we will be endangering ourselves by destroying the home in which we evolved, and on which we completely depend.”
– Edward O. Wilson
Simply put, biodiversity is the variety of life. But what exactly is this variety of life, and how is it represented in the natural world?
To date, science has described around 1.5 million species which have evolved since Earth’s last mass extinction event around 65 million years ago. The true number of species, however, could be upwards of 10 million, a figure which reflects the truly extraordinary diversity of life on Planet Earth. One of these species is the Tomato frog (Dyscophus antongilii), found only in Madagascar.
But why are there so many species?
Biodiversity is fundamentally about difference. The evolutionary process of adaptation, which allows an organism to survive in a particular environment, brings with it divergences both between and amongst species and indeed between different ecosystems. Amazing examples can be found aplenty, from the luminescent fleshy growths (esca) which grow from the heads of anglerfish in the deep seas, to the flaps of skin (patagia) which allow flying squirrels to glide across the forest canopy.
Biodiversity reflects the responses of organisms to their different environments. In certain places where the environment presents unique challenges and populations experience geographic isolation, for example on islands, in isolated forest valleys or around deep sea thermal vents, new species evolve which can be found in no other environment. Madagascar, the home of the tomato frog with its distinctive colouration, is one particularly striking example of such a place.
Madagascar was isolated from the African continent approximately 88 million years ago, allowing an astonishing variety of unique species to evolve in its geographically and climatically diverse environment. Around 90 per cent of the plants, mammals, reptiles and amphibians found on the island are endemic, existing nowhere else on the planet.
Biodiversity is not just about the variety of species, but also the genetic diversity which exists within each one. As discussed in the first blog in this series, we are not just facing a loss in species diversity, but also in species abundance, and as numbers erode so too does genetic diversity. Genetic adaptations have evolved over many millennia, and in this way biodiversity loss also curtails the evolutionary process. This loss in intra-species diversity in turn reduces the potential for a species to adapt to uncertainties and changes to its future environment and thus reduces resilience, thereby increasing their vulnerability to extinction, particularly in the current context of unprecedented rates of environmental change.
So what? Why should we be worried about biodiversity?
In the first instance there are some utilitarian arguments, and they make good sense. Recently there has been an acknowledgement of the value of ecosystems, of which biodiversity is the cornerstone. Ecosystems remove carbon dioxide from the atmosphere; purify drinking water; take toxins and pollutants out of the environment; provide an array of medicinal products; defend us from natural hazards and disease – the list goes on. Ecosystems are also often viewed in terms of their monetary value, a perspective which can misleadingly imply that they could be replaced by other forms of capital.
The fact is, Earth is our life support system, and by allowing species to go extinct, or upsetting the balance of species within particular ecosystems, we start to disrupt and destroy this system. Human ‘development’ is not tied to the extinction of species and destruction of habitats. Indeed, in the long run, quite the opposite is true.
Biodiversity is in some ways akin to a gigantic, dynamic and constantly moving jigsaw, where each piece is constantly changing shape as the environment and the other components of the jigsaw change. Remove a piece, and the knock-on effects can be profound, and even where the reward for conserving a species is not immediately obvious, our understanding of the natural world as being composed of such systems confers a value to each component. For example, the value of a bolt is not really clear until it is understood within the context of an aircraft’s engine.
Whilst nature and biodiversity undoubtedly provide vital economic services or functions, they are fundamental to human wellbeing in other, less utilitarian ways. In many communities nature remains an integral component of culture and belief systems, and even in societies where aspects of culture have long been removed from the natural environment, people still uphold a fundamental emotional connection with wild spaces, which inspire us with a sense of awe and wonder, and their loss still fills most with sadness and melancholy.
Humans can never be totally isolated from nature. But even if we do somehow remove ourselves from the equation, surely other species have the same fundamental rights to survive and prosper on this planet as we do? Each species has evolved to fit into the web of life, but many of these same species are being destroyed in an extinction crisis which is not blind: in the main we know how and why biodiversity is decreasing, and in almost all cases there is something we can do about it. Indeed if we can put even a small fraction of the effort and ingenuity invested in the activities driving this loss of biodiversity into saving these species, then surely we can sustain the amazing diversity of life which has evolved alongside us on this planet. Preserving unique and incredible biodiversity hotspots like Madagascar and allowing species like the Near Threatened tomato frog to continue to thrive for generations to come must surely be a priority for our own and future generations to come.