In Alberta, we identify eleven subspecies in the General Wildlife Regulation of the Wildlife Act. What does this mean for law enforcement and the courts? What does it mean for wildlife managers? There are diverse and strongly held opinions about this. Without agreement among scientists, how can the lay public understand right and wrong, legal and illegal. How can wildlife officers or the courts know what is expected of them? How should wildlife legislation be modified to alleviate confusion and to make the law more pragmatic and functional?
Subspecies listed in Alberta's General Wildlife Regulation
Big Game Cervus elaphus manitobensis Manitoba elk Cervus elaphus nelsoni Rocky Mountain elk Cervus elaphus nannodes Tule elk Cervus elaphus roosevelti Roosevelt elk Ovis canadensis canadensis Rocky Mountain Bighorn sheep Endangered Species Rangifer tarandus caribou Woodland caribou Rangifer tarandus groenlandicus Barrenground caribou Bison bison athabascae Wood bison Upland Game Birds Meleagris gallopavo merriami Merriam's turkey Excluded Meleagris gallopavo gallopavo Domestic turkey Bison bison bison Plains bison
In the Cervus and Rangifer examples, each subspecies is listed in the same category of wildlife. They are distinguished from other subspecies not present naturally in Alberta which would be recognized as exotic by default under the Wildlife Act, section 1(1)(d). Bison and Meleagris subspecies are split between different items of Schedule 1 under the regulations. In each case a "domestic" form is excluded and not subject to restrictions that apply to the other subspecies. The intent is to allow unrestricted private ownership and commercial enterprise with excluded subspecies and is radically different than the implied intent for endangered subspecies like wood bison (B. b. athabascae) or even upland game birds (M. g. merriami). In recent years there have been bitter legal conflicts about subspecies taxonomy. Logic suggests that judicial sympathy would be on the side of any person brought before the court under subspecies regulations and that it would apply the most permissive interpretation in its judgement. Most difficulty arises from the imperfect and frequently arbitrary field of taxonomy. Taxonomy is a science only in a liberal sense. It was intuition and not experimental method upon which taxonomy was founded in 1758 by Linneaus.
He described a system of binomial nomenclature upon which we base the study of taxonomy today. It has only one tentative principle upon which to base its claim as a science. The 'Biological Species Concept' (BSC) is the criterion for recognizing species and was not defined until 1940 by Mayr (182 years after Linneaus). Still the field of taxonomy relies heavily upon taxonomic intuition but the BSC remains as the best criterion for defining species. Until 1940, taxonomists sought a definition of species but had only an intuitive idea that species really existed in nature and many doubted that species were more than artificial units. One might assume, because it took so long to define species, perhaps in due course precise criteria to identify subspecies will be found. That is not possible because the definition of the species precludes such a possibility. A species is the smallest unit of reproductive isolation. Any variants below the species will be nondiscrete. Hybrids will be common and morphological variation and DNA variation will be continuous and unreliable to assign individual animals to subspecies with absolute certainty.
Taxonomy and wildlife legislation are confounded by interspecific and intraspecific hybrids. Not only is it difficult for the law to recognize hybrids but very seldom have wildlife managers clearly determined what their objectives for hybrid animals should be. Hybrids between subspecies are difficult to recognize and the management of such hybrids is confused at best. Hybrids of two species are a bit easier to recognize and to manage.
WHAT IS A SPECIES?
The BSC says "that groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups are a species." What do we mean by "reproductive isolation" when we define the BSC. It does not imply, as many people often suggest, that cross fertility between two individuals is the definitive test of conspecifics (same species). The BSC recognizes many isolating methods in nature. Behavioural and ecological differences may be just as important in reproductively isolating similar species that are sympatric (occupy the same range) or occupy adjacent ranges (allopatric) and have an opportunity to interbreed. Nor does it mean to say that individuals producing fertile offspring in an artificial setting are of the same species.
In practice it is difficult to test the validity of the biological species concept between individuals. There is a large degree of subjectivity in assessment of potentially interbreeding populations. Fortunately, reproductive isolation confers upon most species, morphological discontinuity related to specialized ecological niches and recognition of conspecifics for mates and as territorial competitors. In other words, each species usually looks different from other species and can usually be distinguished by other species. These differences become the tools of the taxonomist. Morphometric differences are measurements of homologous body parts between individuals or the ratio of measurements of several homologous parts. Differences between species range from subtle to profound. Thus it is usually possible to describe species by their morphological differences. In most cases these are apparent at long distances in the field. Moose, elk and caribou are easily distinguished by any person who is familiar with their differences even at long distances. However, other species such as white-tailed deer and mule deer have more subtle differences and require more careful examination to make a distinction. In some species the distinction is very subtle and animals must be examined in hand to make a conclusive determination.
One difficulty with morphological characters that taxonomists have had to work around, is that they are not entirely determined by heritable genetic factors. This is the familiar "nature versus nurture" argument. Nutrition, climate, photoperiod or stress may affect morphological characters in individuals in ways that are not inherited. Today, taxonomists have begun to use a more direct measure of heritable differences that are not affected by environmental factors. DNA analysis reveals polymorphisms (multiple forms) at the molecular level that may distinguish individuals, populations and species. The advantage of DNA analysis is that it reflects very closely the heritable differences between animals, it may reveal relationships between closely related populations (phylogeny) and it may tell us how long populations have been apart or the extent of cross fertilization between populations. The disadvantage of DNA analysis is that it is not normally possible to ascribe DNA types to functional, ecological or morphological differences. Many people have assumed that DNA analysis is a more sensitive method to determine differences but that is not necessarily true. Mitochondrial DNA relationships often conflict with those indicated by traditional species or subspecies designations, that is they do not have phylogenetically distinct DNA (Cronin 1993).
Pre-Darwinian biologists believed that species were fixed unmutable entities. Post-Darwinian biologists began to question the meaning of species and some were convinced that "species" was an expression of opinion, not fact (Gregory 1932). The eminent taxonomist and evolutionist, Thomas Huxley, predicted in 1880 that "it may be as well to give up the attempt to define species and content oneself with recording the varieties..." (from Gregory). This belief arose from confusion and frustration about the difference between species and races. Without the benefit of the BSC, persistent efforts were made to delimit species by the sterility of hybrids. Although taxonomists of that era were moving in the right direction, they were confused by numerous exceptions of fertile interspecific hybrids and sterile intraspecific hybrids.
The Biological Species Concept certainly has not eliminated confusion. It has significantly reduced confusion and it has given biologists and taxonomists confidence that species are a fact and not merely an expression of opinion.
Thomas Henry Huxley
WHAT ARE SUBSPECIES AND POPULATIONS?
Within any species there may exist a range of morphological variation. Although species can be identified by their physical appearance, they are not all exactly alike. Any subset of individuals within a species may exhibit characteristics that are unlike those of other such populations of the same species. We believe them to be the same species because we have evidence of natural interbreeding where their breeding range coincides or we simply doubt there is substantial reproductive isolation between them. Within a population most individuals may exhibit characters that distinguish the population but there are usually individuals within a population that have a few or even many characters of other populations. Therefore, we may say, a population of a species is largely distinct but it is impossible to assign any individual to a population with absolute certainty.
In their lucid but much neglected article, Wilson and Brown (1953) quoted Moore (1949) who said, "there is no generally accepted and easily applied criterion for recognizing subspecies." Forty-five years later no one has yet described general criteria to recognize subspecies. Wilson and Brown concluded "the subspecies concept Is the most critical and disorderly area of modern systematic theory." They emphasized the geographic component of variation within a species. They encouraged taxonomists to classify geographic races and to reject classical taxonomy below the species level. No one to my knowledge, has provided sound criticism of Wilson and Brown's arguments against subspecies as a taxonomic entity. Wilson and Brown wrongly predicted the demise of trinomial, subspecies taxonomy. They foresaw an end to "the ponderous subspecies lists gravely entered in a thousand catalogues, (and) the awkward labeling of masses of intergrade specimens." In spite of their prediction, subspecies taxonomy has endured and even expanded, not because their concerns have been discredited but because they have been ignored. Countless careers and research grants have been founded upon fallacious diversions on subspecies taxonomy. Endangered species lists have been needlessly inflated with taxonomically described subspecies to increase alarm and therefore program funding. There are clear but questionable motives to ignore the concerns of Wilson and Brown. These are not consciously deceptive motives but nor are they informed about the consequences of taxonomic applications below the species level. The profusion of subspecies diverts management effort and protection from true species.
WHAT IS A HYBRID?
Every plant and animal that is a product of sexual reproduction is a hybrid. When we use the word "hybrid" however, it is usually in the narrower context of a cross between different species, races or genetic types. When the word is used to refer to crosses between two species some might think this is a contradiction of the biological species concept. In Alberta we have an excellent example of interspecies hybrids in white-tailed deer and mule deer (Wishart 1980). The occurrence of hybrids is not inconsistent with the BSC nor does it imply that two species are one species. To be considered one species, two forms must produce fertile and viable offspring in every sense. Hybrids of white-tailed and mule deer may be fertile but their fitness is reduced. The combination of intermediate characters and behaviours of the two species has not produced offspring competitively adapted to a specific niche in Alberta. There may be gene mixing between the two species but they continue to be widely divergent in morphology and behaviour. Reproductive isolation between these species persists.
For now hybridization is a long way from breaking down reproductive isolation and morphological distinction between them. In the future, hybridization may become more common and species barriers between mule deer and white-tailed deer could break down. On the other hand, reproductive isolation between these species may generate greater divergence and hybrids would no longer occur. Hybrids between full species are rare in nature and we seldom have to deal with them in wildlife management. Hybrids between geographic races or subspecies are abundant and this is why it is inappropriate to attempt to define laws for subspecies. Experts may be able to assign individual specimens to a subspecies by circumstance if the point of origin is known. We almost always return to geographic origin when we speak of subspecies. Extreme variations between subspecies may be apparent but variations between any subspecies and a hybrid are not. The U.S. Fish and Wildlife Service had a Hybrid Policy under its Endangered Species Act that discouraged protection for hybrids between species but was also applied to hybrids between subspecies (O'Brien and Mayr). Thus there was doubt that any individual was not a hybrid of two or more subspecies and protection was diminished for all subspecies. At the time of writing the U.S. Fish and Wildlife Service is drafting a revised Hybrid Policy that is to be released in December of 1993.
WHERE DO THE LAWS FIT?
If ignorance of the law is no excuse, than the law surely must be widely comprehensible and unambiguous. In law, we should avoid the assertion that "some experts agree . . . " if we expect the public to understand and follow the law. The dependence upon DNA analysis, or other expert opinion, to legally define similar populations is not practical. Expert opinion will continue to be necessary for species in a few cases. Two recent articles have looked at the implications of modern taxonomy for wildlife legislation and enforcement (O'Brien and Mayr 1991 and Geist 1992). Neither of these articles acknowledge the recommendations of Wilson and Brown. Both articles persist in recognizing taxonomic structure below the species level. Both recognize severe problems when subspecies are given legal status, but neither proposes a practical solution.
O'Brien and Mayr said subspecies are "populations that differ taxonomically from other subdivisions of the species". This is an open-ended definition that does not provide criteria to define or identify subspecies. Geist rejects traditional taxonomic methods using comparative morphometrics because he says this method is fatally flawed. He says that every morphological character "conceals genetic, epistatic, environmental and statistical variation," a truth which taxonomists have long recognized, but he does not propose a practical alternative to replace morphometrics as a taxonomic tool. His position is confusing because he persists in using subspecies and he rejects traditional morphometric taxonomy upon which they are based. Geist has recognized the critical problem of taxonomy in law but in rejecting comparative morphometrics he has not revealed a system for more practical legislation.
Except for reindeer (Rangjfer tarandus tarandus), classified as domestic, British Columbia has avoided the use of subspecies in its wildlife regulations. The B.C. Wildlife Act uses the broadest taxonomic groups wherever possible in its legislation and thereby has avoided many problems. Alberta, Ontario and the U.S. Fish and Wildlife Service each have legislation and regulations that widely recognize subspecies. In Ontario, Bill 162, an Act to amend the Game and Fish Act proposes schedules that include 26 subspecies (mostly reptiles and amphibians) and the Endangered Species Act of Ontario lists seven subspecies. The Endangered Species Act of the U.S. Fish and Wildlife Service includes 186 subspecies in its list of 814 endangered or threatened species (about 23%). Each of these implies that it will defend the identity of a subspecies in a court of law if required to do so. And yet, in forty years, no one has provided a satisfactory rebuttal for the arguments of Wilson and Brown, who tell us that there is no validity for defining subspecies. A clever cross-examining lawyer could discredit any expert witness who attempts to defend the taxonomic identity of any subspecies in any court. What witness can provide non-arbitrary criteria for defining subspecies? There are none. Consequently, there is no validity to the argument that an individual animal must be from a particular subspecies because it has a particular set of morphological features typical of that population. It could be equally valid to propose that it belongs to an alternate population, that it is an exception within a population or that it is a hybrid between two populations.
Many jurisdictions have drafted legislation to control activities associated with captive wildlife in toes, game farms, breeding facilities and recovery centers. In these facilities the point of origin may be impossible to determine particularly for subsequent generations born in captivity. The use of subspecies taxonomy is not a solution in this case either. The same problems persist. Certainly, captive wildlife problems should not be used as an excuse to retain nonfunctional taxonomy in legislation. The primary purpose of wildlife legislation must be to protect and enhance free wildlife for the benefit of citizens.
WHAT IS THE FUTURE FOR TAXONOMY IN LAW?
It should be evident that laws cannot be applied unless words used in the laws can be precisely understood. Subspecies should be struck not only from all environmental and wildlife law but from all scientific usage. This does not mean that managers must forget about managing populations, ecotypes or geographic races. Nor does it mean that laws cannot be drafted to protect these populations. In the future, legislation to protect populations should be defined with respect to geographic origin of an individual through zoning regulations. Convictions under
this legislation would be based upon proof of the point of origin and not an obscure and arbitrary taxonomic identity. In most cases an expert witness today would rely upon knowledge of the point of origin to assist his identity of a subspecies. Why not give the public the same benefit when drafting legislation by using expert knowledge to define protection zones for geographic races in advance. Other jurisdictions might do well to consider British Columbia's wildlife regulations and British Columbia might do well to reconsider its single exception, reindeer (Rangifer). Wildlife managers manage populations of animal species.
Wildlife managers are concerned about protecting the genetic diversity of animal species and diminishing the excessive influence of man and his enterprises on natural populations of wildlife (COSEWIC c1991). Wildlife managers depend, in part, upon the law to help them in their effort. However, the law does not and cannot deal at the same level as wildlife managers. The law deals with individual cases and individual animals and not populations.
To improve understanding of the law and the implementation of the law, wildlife acts and regulations must, in the future, follow the principles of taxonomy as described by Wilson and Brown. They must not rely upon formal taxonomy below the species level. Management zones can be described that include the known range of geographic races within which restrictions can be applied. Law enforcement personnel must recognize that they cannot rely upon experts to distinguish individuals of subpopulations upon morphometric or any other character of the animal. The only distinction can be the point of origin. The law should recognize the expertise of wildlife managers to identify geographic zones that contain important populations and their ranges but it should also recognize that experts cannot assign individual animals to that population without knowledge of the point of origin.
There may be circumstances in which, for tactical reasons, managers prefer to use taxonomic subspecies designation in regulation on a temporary basis. Such exceptions should be discouraged so that functional taxonomy becomes the normal practice in law and that laws are divested of indefensible subspecies as soon as possible. This will diminish another problem in law and that is hybrid status. Hybridization between species is far less common than between subspecies. Hybridization between species, such as white-tailed deer and mule deer is not a problem where both species are given similar protection by law. Hybrids can be specifically protected as well. In this example, legislation should be drafted to protect all individuals of the genus Odocoileus which would include hybrids.
O'Brien and Mayr describe four natural fates, over time, for subspecies (geographic races).
- go extinct;
- exchange genes with another subspecies and become a "mixed" species;
- by genetic drift, selection, subdivision, or other demographic processes change its genetic character to become one or more new subspecies;
- become a new species by acquiring reproductive isolation.
An uninformed response to the fates listed above is that only (4) is desirable and that should be the goal of wildlife management. This view rejects the role of natural selection and imposes our preference for saving everything in nature (essentialist conservation). The more pragmatic (and functionalist) approach is to limit, within reason, the impact that man has on populations and to allow fate and animal fitness to make the choice equally between all four of the options above. The impact of man will always be present (as long as man is) and we would be naive to expect to eliminate it entirely. Man is part of nature and the modern environment. We should however, attempt to diminish man's dominance in nature by conserving functional and diverse ecosystems. The law can best serve that objective by protecting species described taxonomically and populations described geographically.
COSEWIC. c1991. Recommendations of the COSEWIC populations subcommittee: Guidelines for listing groups below the species level. report of the Population Subcommittee to COSEWIC. 5pp.
Cronin, M.A. 1993. Mitochondrial DNA in wildlife taxonomy and conservation biology: cautionary notes. Wildl. Sec. Bull. 21:339-348.
Geist, V. 1992. Endangered species and the law. Nature 357:274-276.
Gregory, J.W. 1928. The nature of species. in Creation by Evolution. (ed. F. Mason) The Macmillan Co. N.Y.
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Mayr, E. 1940. Speciation phenomena in birds. Amer. Nat. 74:249-278.
Mayr, E. 1963. Animal species and evolution. Harvard University Press. Cambridge, Mass. p 797.
Moore, J.A. 1949. Geographic variation in Rana pipiens Schreber of eastern North America. Bull Am. Mus. Nat. Hist., 82:349-369. (from Wilson and Brown).
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Wishart, W.D. 1980. Hybrids of white-tailed deer and mule deer in Alberta. J. Mammal., 6(4):716-720.