Bu recent article in the American Naturalist has taken a second look at some of the famously inflated species estimates, kimi bəzi gedən yüksək 100 milyon (Erwin, 1988). Müəllifləri tərəfindən keçirilmiş hesablamalar göstərir ki, yuxarıda proqnozlar 30 milyon ehtimallar var <0.00001. Onların təxmin sıra arasında daha çox 2.5 və 3.7 million species (ilə 90% confidence). This seems somewhat reasonable given that these extraordinary estimates were based heavily on extrapolation. There are clearly many difficulties in assessing diversity based on tropical arthropod surveys – this paper again uses phytophagous (plant-eating) beetles for estimates. They are careful to point out that these methods do not account for non-phytophagous insects, but assume that they will follow traditional biogeographic patterns of diversity. This is somewhat of a new concept given that when I was in college I was taught that parasitoids are counterintuitively not more diverse in tropical regions. Bu fərziyyə, daha dəqiq müasir taksonomik metodologiyanın işığında daha tez-tez yalan olduğunu sübut edir.. Əksinə qürurla bir rol oynamağa kömək etdim parazitoid layihəsi UIUC-da. Qısa, Mikroqastrin Brakonidləri kimi sürətlə şüalanan qruplar arasında gizlənmiş yüzlərlə sirli növün olduğu tropik mühitlərdə ev sahibinin spesifikliyi daha ekstremaldır. (Hymenoptera) – eyni şey oxşar taksonlara da aiddir.
Kağızla bağlı maraqlı qeydlərdən biri də Lepidoptera çəmənlik birləşmələrinə əsaslanan ikinci dərəcəli qiymətləndirmənin daxil edilməsidir.. Onlar güman edirdilər ki, a) bütün Lepidoptera örtüdə tapıla bilər və b) ki, bütün lepslər fitofaqdır. Bu, açıq-aydın çox mühafizəkar bir qiymətləndirmədir, nəzərə alsaq ki, bütün Lepidopteralar örtüdə tapılmır və hamısı fitofaq deyildir.. Nömrələrim əlimdə olmadığı halda, a certain percentage of lep diversity must have been excluded from these estimates. I will also go out on a limb and assume that the authors (Novotny 2002) did not include microlepidoptera morphospecies – and most likely estimated abundances with our current taxonomic understanding. However I do not have access to this 2002 paper, so I may be incorrect. Using these Lepidoptera numbers (from the same survey as the Coleoptera) a global diversity was estimated by Hamilton et. al. at around 8.5 millions arthropod species.
While I agree that extraordinary estimates of tens of tens (or hundreds) of millions of arthropod species are probably ridiculous; I am of the camp that current research is indicating that estimates of the lower tens of millions of species are possible. The authors have failed to include research that counterbalances their premise that tropical species exhibit a lower beta diversity (Novotny 2002, 2007). In the same journal, Təbiət 2007, Dyar et. al. have indicated that the American tropics exhibit a higher beta diversity than previously assumed. Either it can be said that estimates of beta diversity in the australasian tropics are incorrect, or they are incompatible with species assemblages of neotropical forests. All of this speaks to the difficulty in extrapolating estimations of species across all tropical regions. These estimates are based on comprehensive insect surveys of New Guinea, perhaps they do not accurately reflect the true diversity of American tropical forests, and these number ranges are low.
As a final thought, most assesments are focused on tropical arthropods. It seems all too possible that the total number of all species, including bacteria and archaea, can easily exceed tens of millions. But extrapolating those numbers is even more precarious than arthropods, given the extreme lack of knowledge we have.
