The Nonconcept of Species Diversity: A Critique and Alternative Parameters

Abstract

Abstract. The recent literature on species diversity contains many semantic, conceptual, and technical problems. It is suggested that, as a result of these problems, species diversity has become a meaningless concept, that the term be abandoned, and that ecologists take a more critical approach to species-number relations and rely less on information theoretic and other analogies. As multispecific collections of organisms possess numerous statistical properties which conform to the conventional criteria for diversity indices, such collections are not intrinsically arrangeable in linear order along some diversity scale. Several such properties or "species composition parameters" having straightforward biological interpretations are presented as alternatives to the diversity approach. The two most basic of these are simply:counters which is interspecific (as opposed to intraspecific), assuming every individual in the collection can encounter all other individuals, and = the expected number of species in a sample of n individuals selected at random from a collection containing N individuals, S species, and Ni individuals in the ith species.Ever since Fisher, Corbet, and Williams ( 1943) proposed the diversity index oc and, more recently, since MacArthur (1955) and Margalef (1958) proposed indices based on information theory, community ecologists have put much effort into the mathematical and statistical refinement of these indices, the devising of new indices, the calculation of diversity for various collections of organisms, and the correlation of diversity with other variables. These efforts have sometimes been at the expense of more substantive approaches to community ecology. The term "species diversity" has been defined in such various and disparate ways that it now conveys no information other than "something to do with community structure"; species diversity has become a nonconcept.The present paper offers a critique of semantic, conceptual, and technical problems in the diversity literature and suggests that ecologists take more direct approaches to the study of species-numbers relations. It treats only empirical measures, i.e., those calculated directly from the observed relative abundances of the species in a collection. Theoretical in-1

Diversity and structure of Ephemeroptera, Plecoptera and Trichoptera (Insecta) assemblages from riffles in mountain streams of Central Brazil

“…The rarefaction curves (HULBERT 1971, SIMBERLOFF 1972 were computed through Monte Carlo permutations. In order to estimate the number of taxa to k individuals, k individuals were randomly taken from the samples and the number of observed taxa was registered.…”

Ephemeroptera, Plecoptera and Trichoptera assemblages in litter in a mountain stream of the Atlantic Rainforest from Southeastern Brazil

“…Richness was evaluated by rarefaction curves (HURLBERT 1971, SIMBERLOFF 1972) using a Monte Carlo permutation method. To estimate the number of taxa for k individuals, k individuals were randomly withdrawn from the sample and the observed number of taxa was recorded.…”

Nucleation in tropical ecological restoration

“…Facilitation plays a significant role in structuring plant communities (Bruno et al, 2003). The positive interspecific interactions (Hurlbert, 1971) and connectance (Williams and Martinez, 2000) among the diverse trophic levels are essential to many organisms' life history strategies. Hence, the theoretical framework of modern ecology should be updated by including the concept of facilitation.…”