Research Training Program

Andrew Farke
South Dakota School of Mines and Technology
Rapid City, South Dakota

Jonathon A. Coddington, Ph.D.
Supervising Scientist
Department of Entomology

"I have expanded my scientific horizons beyond what I ever thought possible."

Estimating the number of species in a clade (a branch on the tree of life) is a hot topic in global ecology. Such figures can be important in stimulating conservation efforts and offer a standard with which to gauge diversity. Until now, they have been derived through extrapolation or polling expert opinion. Our research investigated the feasibility of applying richness estimators to this problem. Richness estimators consider the number of species observed in a random sample, especially proportion of rare species (those known from only one or two specimens or localities), and estimate how many species would be found if the population was exhaustively sampled. Richness estimators are often used in ecology to estimate the number of species in a locality or region, but they have not been applied to clades. Using published and unpublished museum data, we calculated clade richness for taxa ranging from spiders to snakes to hominids. The results indicate that some clades are better known than others are. For instance, 37 species of South American Bombus (bumblebee) are known, and the calculated richness values are very close to this (a maximum value of 38). Consequently, it appears that this group is quite well sampled. However, sphecozonoid spiders (a clade of small, neotropical genera) appear to be a very poorly sampled group. Fifty-six species are currently identified, with estimator values of 88 to 132 species. The majority of analyses were somewhere between. Fossil hominids, for example, have a total of 14 observed species with a maximum estimated number of 18. Based on our analyses, we feel that richness estimators have great potential for estimating the size of a clade, and can help assess the completeness of the knowledge of a group.

This research was supported by a grant from the Alice Eve Kennington Internship Endowment.