Diversity of Life
The Earth has a range of variety of life forms that defies the imagination. There could be as many as a trillion species, and only a tiny number of these have been identified and studied. There have been at least 5 great mass extinctions since the beginning of multicellular life. We are currently provoking a sixth.
Biodiversity of an ecosystem is the diversity of species and the richness of these species.
The diversity of life, and the need to maintain it, is instinctive to our concept of a healthy planet. Biodiversity of an ecosystem is therefore both the diversity of species and the richness of these species. Long-term stability of an ecosystem depends on ensuring that the proportions of population numbers reflect the species' respective roles within the ecosystem, determined primarily by their trophic level.
Officially, Biodiversity is defined as the "totality of genes, species, and ecosystems of a region". The types of diversity involved are:
- Taxonomic (species diversity)
- Ecological (diversity of habitats)
- Morphological (intraspecies genetic diversity)
The recognition of the threats to biodiversity has prompted worldwide efforts to protect species from losing their habitats. Although all species in a habitat are mutually dependent, for practical and political reasons, special focus is given to endangered species.
Living Planet Index LPI
The Living Planet Index, a publication on the "health" of more than 3000 species (species) and more than 10,000 populations, published by the WWF (2014) in the "Living Planet Report", is regarded as a measure for the development of biodiversity.
The 2014 report shows the decline in global biodiversity by over 50% between 1970 and 2010. Freshwater species in the rivers and lakes were 76% lost, through fragmentation and pollution of habitats, and invasions of non-endemnic species.
Land degradation losses are 39%, due to changes in land use, the expansion and intensification of agriculture (monocultures, overcrowding, soil erosion, pesticide use, pollutant inputs by fertilizers), shrinkage and degradation of habitats (e.g. deforestation), urbanization and transport axes (fragmentation of habitats).
Marine species: 39% loss, largest in tropical waters and in the southern oceans. Almost 50% of fish stocks in European waters are considered overfished.
According to the Red List of Endangered Species (2015) drawn up by the IUCN (International Union for Conservation of Nature and Natural Resources), 22,000 species are acutely endangered, including 41% of amphibians, 33% of reef-forming corals, and 25% of all marine fish stocks, 25% of mammals and 13% of birds.
Conservation of Endangered Species
Biodiversity and endangered species are two issues which are often bundled together, especially in NGO public awareness campaigns. However, saving a specific habitat for a single species is not necessarily the same as preserving a region's biodiversity.
CITES, the WWF, and other environmental organisations are concerned with the rapid depletion of biodiversity, and use certain endangered species, like the whale and panda, to promote pubic awareness of the problem. However, combating biodiversity loss does not mean targeting single species, but entails preserving a healthy genetic diversity of all species, populations, and communities, within a healthy, sustainable habitat.
This applies at all scales, whether a local area, a biome, or the planet as a whole.
Since the planet is spherical, the solar energy available for photosynthesis is not equitably distributed, creating zones with greater primary production (vegetation) than others. In addition to the latitude, factors such as location along coasts, precipitation, and altitude play significant roles in determining how rich an area is in terms of biodiversity.
Some conservation movements choose to focus on biodiversity 'hotspots', in order to obtain the greatest possible benefit. Choosing what to try to save is inevitably going to be controversial, in particular since the public, who fund these NGOs, are more likely to respond when the project is about a species with 'marketable' emotional response value.
Extinction is a 'Way of Life'
Ironic as it may sound, the purpose of life is extinction. A somewhat disturbing fact is that nearly all species that have ever lived on the Earth are now extinct. There is a theory that the telomeres, protective 'caps' on chromosomes, do not get passed on perfectly with each generation, leading to an eventual breakdown in a species' genetic robustness. This is particularly prevalent in more complex organisms. Considering that every other hominin species (and there have been more than 20 that we know of) has passed by way of extinction, the human species can expect to have a use-by date stamped somewhere in its genes.
Scientists are finding new species all the time, but estimates put the total of species as between 10 to 14 million. Only 10% of these (1.2 million) have been named. Life is truly diverse and rich.... and short-lived.
There have been a number of periods in Earth's history in which life diversity has taken a dive. Particularly intensive and rapid periods of biodiversity depletion are termed 'Mass Extinction Events'. There have been five mass extinctions that we know of, and we are currently in the sixth.