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Question 1.

Our first criterion is that the species name and status must be valid systematically. This statement indicates that we are using standard rules of nomenclature, and that for this survey we are interested in counting organisms on the level of species. We have chosen "species" as the basic unit to count for practical reasons. It is the most widely accepted and recognized biological unit, particularly in terms of having the greatest acceptance and practical value to conservation policy. Thus, we are not counting subspecies or populations. If we include these units, we risk producing lists that are too confusing and complicated to be understood or used by relevant consuming groups. Do you agree or disagree with this rationale?

If you disagree, what species concept do you think works best for this kind of study, and why?

  • Comments by CREO Chairman, Ian Harrison, have been added to some of the responses below -- in underlined text.

    Amphibians Advisory Panel

    Comment 1: it may be useful to categorize extinction geographically (eg., extinct in the UK) because:

    1) detailed information is better in some geographic areas than others.

    2) we are interested in causes of extinctions and geographical information can be very illuminating about causes. (Will this create difficulties in terms of deciding what regions you select for study? For example, islands are easy because they are self-contained; but continental studies tend to be biased by political boundaries rather than geographic ones so they become meaningless in any biological explanation. Also, CREO then starts dealing with extant species which are being thoroughly analyzed by IUCN etc and we risk a significant duplication of effort.)

    Related to this, extinction studies may be useful at the subspecies level. Many subspecies have distinct ranges e.g. islands, so their status is informative about the causes of extinctions. Many subspecies later become classified as species through genetic research.

    Comment 2: agrees with rationale as stated in Question 1.

    Comment 3: agrees with rationale as stated in Question 1.

    Comment 4: Categorizing available species names as extinct in a milieu of a poor taxonomic framework will artificially amplify the number of "extinct" species. Therefore, it is important to assess the validity of species names according to reliable taxonomic principles (e.g. ICZN).

    Subspecies tend to be used arbitrarily among some groups of animals and it is important to assess whether these subspecies should be considered -- where they are supposedly well understood (e.g., birds). The increasing application of DNA techniques is giving rise to a new 'subspecies concept' where genetically distinct but morphologically indistinguishable populations are being described or recognized as subspecies. A possible solution to the problem of whether or not to recognize subspecies would be to recognize those that have been validated in taxonomic works in the past 25 years. Disregarding subspecies might result in a large and important measure of diversity being neglected.

    Although populations are inconvenient units to handle, they are very important in conservation consciousness and planning. Population extinctions should be accommodated in the CREO criteria at least at the level of national extirpations: a population extirpated in one country can never be replenished from that of another. (Although CREO criteria could easily be applied to evaluating individual populations, and global extinctions effectively start with local extinctions, we should be careful not to overlap too much with the existing work of SSC etc., and provide conflicting or confusing assessments of extant species.)

    Birds Advisory Panel

    Comment 1: agrees with taxonomic criteria and biological species concept.

    Comment 2: in general accepts a biological species concept but would accept subspecies because there would not be too many subspecies to deal with; or would accept a moderately expanded species concept that would include highly distinct subspecies.

    Comment 3: phylogenetic species concept is imperative.

    Comment 4: agrees with the use of species and not subspecies, but the "definition" of species — the concept used — must be uniform. Prefers the phylogenetic species concept, because if the species is diagnosable, then it should be recognized. This applies especially to allopatric forms of birds. At present, there is much diversity that is not taxonomically recognized. Questions of infertility are too difficult to judge.

    Comment 5: agrees with the use of species as the rank for analysis and equates this most closely with the phylogenetic species concept. States that, in practice, this equates diagnosably distinct taxa, in morphologically based phylogenetic analyses, with species.

    Coleoptera Advisory Panel

    Comment 1: species are the elemental units for this kind of work. Although regional, intra-specific protection programs are valid and necessary, theirs does not fall within the purview of extinction study per se. Although controversial, there's really no cogent alternative to adopting the phylogenetic species concept, because it is character based and is rooted in direct observation of characters on organisms. Under this usage, subspecies become justifiably irrelevant - if they are diagnosable, they are phylogenetic species.

    Comment 2: the species rank is the only suitable rank to be used. Application of the phylogenetic species concept is compatible with this approach; i.e., only sets of population samples diagnosable from others should be considered a datum for preservation.

    Comment 3: agrees with the rationale.

    Comment 4: agrees - species level is the most objective.

    Fishes Advisory Panel

    Comment 1: agrees with the proposed use of 'biological species' but not subspecies. But would include undescribed species which meet the biological species criteria sensu Mayr and are given an official vernacular name.

    Comment 2: likes to use the phylogenetic species concept, recognizing subspecies as full species where they are diagnostic. Also, does not entirely agree with the criteria that both the species name and status should be valid systematically. A species' systematic status can be valid without the species having a name at all. There are many cases where species exist which have not been described for a variety of reasons; some of these may already be extinct, irrespective of whether they have a formal name, and it is very misleading to list them as unresolved.

    Comment 3: partly disagrees. There are cases where subspecies are incipient species. This may cause problems in, for example, desert communities where there is a very rapid evolution rate. In these cases, we should give subspecies the same emphasis as species.

    Lepidoptera Advisory Panel

    Comment 1: with relatively few exceptions, precise specific identification of Lepidoptera may be difficult to apply retrospectively to taxa for which voucher material is unavailable. Much of the recent concern has devolved on subspecies or other local 'forms' and, in general, many of these are accepted sufficiently for valid use as equivalent to 'species.'

    Mammals Advisory Panel

    Comment 1: agrees with taxonomic criteria but notes that taxonomy is changeable and criteria must account for this; e g., subspecies later become elected as full species.

    Comment 2: a species need not be taxonomically named; a manuscript name, genus name + museum registration number + opinion from a recognized expert should be acceptable. (This is covered by MacPhee and Flemming category III - perhaps these should be recognized more clearly, as pre-50 year and post 50-year extinctions, i.e., treat them as regular species. Other panelists have suggested recognizing undescribed species as separate from invalid ones).

    Comment 3: should we account for all species that have been officially described, or only those reviewed by experts for the group; eg. a species can be described according to standard rules of nomenclature and then rejected by others who don't know the group and have not seen specimens.

    Comment 4: agrees with working on species level, but the problem is deciding whether subspecies should be accepted as full species, because many species were first described as subspecies and then elevated to species level. Perhaps accept any taxon that has, within the last 50 years, been referred to in scientific literature at least once as a full species.

    Molluscs Advisory Panel

    Comment 1: argues against the exclusion of subspecies, given the complete lack of any firm dividing line between taxa treated as species and subspecies. It is often just matter of opinion as to whether allopatric taxa are called subspecies or species and often both levels of classification can be in use at any one time. Strongly recommends that subspecies be included.

    Reptiles Advisory Panel

    Comment 1: agrees. Subspecific differences are often practically difficult to assess on the basis of the limited material that is usually available for extinct taxa. Population level extinctions are too difficult to track and are not necessarily important to the species as a whole.

    Comment 2: agrees but questions which "standard" list should be used as the basis for judging taxonomic validity. There is an ASC list for amphibians, and one in press for snakes; Iverson's list of turtles (now being updated); and King and Burke list for crocodilians. However, there is no global listing of the lizards of the world, although one volume of a promised series by Bauer and Henle lists the Australasian species. (The best taxonomic source should be the most contemporary revision for each particular taxon - this may be an individual species description or revision, not necessarily a taxonomic list. But it should also be a publication that is viewed as widely accepted according to the Advisory Panel. Taxonomy is constantly being reviewed and refined and so perhaps we must accept that some judgement calls must be made. In cases where there are unresolvable differences of opinion over taxonomy, which would affect the way a species is categorized, species could be placed in one of the categories that accommodates taxonomically problematic species.)

    Comment 3: agrees with rationale as stated in Question 1.

    Comment 4: agrees. Use species, not subspecies.

    Comment 5: only systematically valid species should be used. Species are, for now, the best unit of conservation and thus should be targeted accordingly. (Clearly what we all hope to preserve when we provide protection for a given species is habitat for other endangered, and potentially endangered species. Protection, and subsequent proliferation of endangered species clearly can only come about in habitats with many non-endangered species).