What is Extinction?
Extinction is the end of a group of organisms (taxon), normally a species. The moment of extinction is generally considered to be the death of the last individual of the group (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "re-appears" (typically in the fossil record) after a period of apparent absence.
Many factors are driving an unprecedented rate of extinction of plant and animal species world wide. Although extinction is a natural process, the rate at which current extinction is taking place is clearly not, and all scientific evidence indicates that the activities of man kind are the primary engine behind most recent and present extinction events.
Major causes of extinction include:
Destructive change to environments or landscapes, either through natural phenomena (such as floods, volcanoes, hurricanes etc.), or human processes (such as construction, deforestation, changing landuse for agriculture, artificial land drainage etc.), is the single greatest threat to the biodiversity of Planet Earth, and the greatest cause of extinction in our world. When a plant or an animal does not have a habitat, and cannot adapt to a different environment, it will become extinct.
Unregulated or Illegal Killing, Hunting or Poaching
Hunting and poaching rare plants and animals is a human cause of extinction that may represent a major, or dominant factor in the decline of certain species, particularly those that are endemic to a small geographic area, or have a small or slow-regenerating population overall.
Unfortunately, across the world, various socio-economic factors drive hunting and poaching of endangered plant and animal species, and where this occurs at unregulated, unsustainable levels, vulnerable species may be pushed towards extinction (i.e. Nepenthes clipeata in Ark of Life’s Rare Nepenthes Project).
Although regulations and legislation may exist at a national or international level (i.e. the Convention on International Trade in Endangered Species), often sufficient infrastructure, awareness or resources are in place for any effective impact (as was this case for Nepenthes clipeata).
Sometimes killing of endangered plants and animals is due to ignorance or misconceived stereotypes, as is often the case of bats, snakes and arachnids that are commonly, but incorrectly perceived to be aggressive or necessarily dangerous.
The introduction of plant and animal species that are not endemic to a given locality is both a natural and human process that often has disastrous knock-on consequences for local biota, often including extinction of native taxa. Introduction of species that are not native to a given area may occur through regular dispersal processes over short geographic distances (i.e. seed being blown in the wind, or in the crop of a bird), but the incidence of such processes occurring naturally is low. Artificial or accidental introduction of non-native plant and animal species occurs much more commonly, particularly as humans travel more extensively and frequently across the globe. Seeds are rapidly transported by humans on their clothes and shoes, and or rats on board ships. Both natural and anthropogenic introduction of non native plant or animal taxa may profoundly upsets the balance of the local ecosystem of a given locality and push the most vulnerable native taxa towards extinction, particularly those that are endemic to a small geographic area, or have a small or slow-regenerating population overall.
Pollution may be a natural or human cause of extinction, and can take many forms. Natural pollution events may result from cataclysmic geographic processes (volcanic eruptions, floods, earthquakes, etc.), or from over-population of ecosystems by specific species (red tide) or other processes. natural pollution events commonly cause local extinction events, but rarely are sufficiently wide scale to cause complete extinction of significant numbers of plant and animal taxa. human pollution can take many forms, but usually arises when toxic substances are dumped, either advertently or inadvertently, into biologically diverse areas of our planet. Anthropogenic pollution may have knock-on consequences, for example, eutrophication. Large scale anthropogenic pollution events (i.e. oil spills) may have the scope to cause the complete extinction of plant and animal taxa, particularly those that are endemic to a small geographic area, or have a small or slow-regenerating population overall. Pollution may impact entire ecosystems, including humans, for example the pesticide DDT, which was used against arthropods up until the 1970s, but causes catastrophic impacts at all ecological levels, from the water and soil, through water feeders, ground arthropods, predators, and humans.
Ongoing evolutionary processes are driven by competition, and over (usually) long periods of time, plant and animal taxa that are unable to adapt may be out competed and naturally displaced from their habitat, and pushed towards extinction.
The spread of disease may be both a natural and human factor behind extinction. Naturally occurring diseases that afflict specific plant or animal taxa may be inadvertently spread by humans with disastrous consequences, for example, Dutch elm disease, which is a fungal disease of elm trees spread by the elm bark beetle. Although believed to be originally native to Asia, the disease has been accidentally introduced into North America and Europe, where it has devastated native populations of elms which had not had the opportunity to evolve resistance.
Many other factors contribute to the extinction of plant and animal taxa of Planet Earth. Much of the destruction to our world’s biota can be avoided with responsible, balances and long-sighted management of the enduring natural areas.
Ark of Life is set up as a pragmatic approach to stop the complete extinction of species that no longer occur in the wild (or practically so). Our collections, or “arks” maintain the genetic diversity of imperiled plants and animals and aim to ensure that a sufficient gene pool persists in artificial culture so that reintroduction into the wild is retained as a viable option for the future, should habitat regeneration take place.