A new paper now estimates that there could be up to one trillion species on earth.
Kenneth J. Loceya, and Jay T. Lennona. Scaling laws predict global microbial diversity. PNAS, 2016 DOI: 10.1073/pnas.1521291113
It seems logical to me that for any environment there has to be an optimum (perhaps many possible such) number of species for the sustainability of those species. Biodiversity is not always good and the current “wisdom” that increasing biodiversity is always a good thing, is not just flawed – it is plain stupid. Evolution is highly inefficient (though it has been effective) and produces far more species than are necessary for the sustainability of life. Since over 99% of all species that have ever existed are now extinct, it follows that evolution has failed every one of those extinct species; and failed each to the point of destruction. Mass extinctions are merely the way in which the detritus of failed evolution is cleaned out. Currently probably some 30% of all species need to go extinct.
I have never yet heard a satisfactory explanation of why ever-increasing biodiversity, which is so politically correct, is a good thing. “The good of the eco-system” is often quoted – but what on earth is that? Is it better to have a multitude of species or a multitude of individuals in a fewer number of species? Is it better for external forces to change an environment (long, slow geologic processes or short sharp catastrophic events) or for the species within the environment to change it? There is a mindless worship of biodiversity which is not logical.
It seems almost self-evident to me that, for any given environment there must be an optimum number of species, with particular combinations of characteristics, which allow the ecosystem or biosphere to be in a self-sustaining equilibrium (not growing or declining but self-sustaining). This optimum will vary depending upon the characteristics and interactions between the particular species existing and the available space in the prevailing environment. Then, having fewer than the optimum number of species in that environment would mean that all the complex interdependent, interactions between species that seem to be necessary for sustaining each of the participating species would not be fully developed. I say “seem” because it is not certain that all interdependencies are necessarily of benefit to individual species. “It is the entire ecosystem which benefits” I hear some say, but even that is more an assumption than a conclusion.
The press release from the University of Indiana
Earth could contain nearly 1 trillion species, with only one-thousandth of 1 percent now identified, according to a study from biologists at Indiana University.
The IU scientists combined microbial, plant and animal community datasets from government, academic and citizen science sources, resulting in the largest compilation of its kind. Altogether, these data represent over 5.6 million microscopic and nonmicroscopic species from 35,000 locations across all the world’s oceans and continents, except Antarctica. ……
….. Microbial species are all forms of life too small to be seen with the naked eye, including all single-celled organisms, such as bacteria and archaea, as well as certain fungi. Many earlier attempts to estimate the number of species on Earth simply ignored microorganisms or were informed by older datasets that were based on biased techniques or questionable extrapolations, Lennon said. ……
……. The study’s results also suggest that actually identifying every microbial species on Earth is an almost unimaginably huge challenge. To put the task in perspective, the Earth Microbiome Project — a global multidisciplinary project to identify microscope organisms — has so far cataloged less than 10 million species.
“Of those cataloged species, only about 10,000 have ever been grown in a lab, and fewer than 100,000 have classified sequences,” Lennon said. “Our results show that this leaves 100,000 times more microorganisms awaiting discovery — and 100 million to be fully explored. Microbial biodiversity, it appears, is greater than ever imagined.”
Scaling laws underpin unifying theories of biodiversity and are among the most predictively powerful relationships in biology. However, scaling laws developed for plants and animals often go untested or fail to hold for microorganisms. As a result, it is unclear whether scaling laws of biodiversity will span evolutionarily distant domains of life that encompass all modes of metabolism and scales of abundance. Using a global-scale compilation of ∼35,000 sites and ∼5.6⋅106 species, including the largest ever inventory of high-throughput molecular data and one of the largest compilations of plant and animal community data, we show similar rates of scaling in commonness and rarity across microorganisms and macroscopic plants and animals. We document a universal dominance scaling law that holds across 30 orders of magnitude, an unprecedented expanse that predicts the abundance of dominant ocean bacteria. In combining this scaling law with the lognormal model of biodiversity, we predict that Earth is home to upward of 1 trillion (1012) microbial species. Microbial biodiversity seems greater than ever anticipated yet predictable from the smallest to the largest microbiome.