Thursday, 2 November 2017

‘For the survival of the species’: The mismatch between evolutionary biology and conservation biology...and 'taxonomic inflation'

'Jock' Marshall
from here
In the 1960s there was a board for newspaper clippings, notices and other ephemera on the corridor wall of the old zoology floor in the now-demolished Northcote Science Building at the University of Hong Kong. At the top was a cutting from an Australian newspaper reporting an interview with the larger-than-life Professor Alan John ‘Jock’ Marshall (1911-1967) then at Monash University in Melbourne. The clearly shocked journalist reported words to the effect that Marshall did not care what happened to individual animals; what did concern him was conserving species and if that meant some individuals dying in the process then so be it.

That, in a nutshell, describes the fundamental mismatch between evolutionary biologist’s view of species compared with that of the early conservation movement and hence, because of the publicity given to conservation activities, that of the public. So we have, on the one hand, biologists wincing when they hear ‘for the survival of the species’ in terms of natural selection while at the same time conservationists talk of their work ‘for the survival of the species’.

Early conservation efforts were seen as direct threats to large animals and in terms of getting the public and politicians engaged with he problem there is nothing so persuasive as a member of the charismatic megafauna. The World Wildlife Fund’s choice the Giant Panda is the most famous example. While there were—and still are—direct and major threats to the survival of individual species, the poaching of rhinoceroses being a prime example, the question of preserving habitats (or whole ecosystems, although I hate the term because it is misleading) tended to be put to one side. If you can conserve the large species, then there will be sufficient habitat for the smaller ones to be protected as well.

However, when it came to national conservation politics legal protection was often based on a species and not on a habitat. Across a wide geographical area, local extinctions from habitat loss or hunting were possible because the species there were either not sufficiently endangered or represented a very small proportion of the total population of the species. So, the pressure was on to increase the number of species by elevating geographical variants (often termed, probably unwisely, as subspecies) to the status of full species. But not only do conservation efforts benefit (if only at first sight) by increasing the number of species. Birders of the tick-list variety just thrive on species being ‘split’ and the tour companies are always at pains to point out the chances of seeing a a new ‘split’ in a particular area. The tourism industry also loves a distinctive name for their familiar animal. ‘This is Thornicroft’s giraffe, madam’ said the guide in Zambia who was surprised when madam replied, ‘Just a giraffe with a geographically distinctive pattern’.

The whole process of increasing the number of species by deviating from the biological species concept has been called ‘taxonomic inflation’. The increase is not new; some taxonomists of old split species ad nauseam but after dismissing the nonsensical claims there were reckoned to be 4,659 mammals in 1993. By 2005 that number had risen to 5,418, not as explained by Shai Meiri and Georgina Mace in their 2007 paper, by an increase in the discovery of new species but by the splitting of existing species. With mammals, that splitting has occurred to the greatest extent in Africa where a species may have a widespread distribution.

Meiri & Mace continued:

Most of these recently described species are allopatric or parapatric (i.e., with ranges that abut but do not overlap) populations, separated by barriers such as rivers. Given a barrier to gene flow, the accumulation of genetic and morphological differences is expected and may be of limited biological importance. It seems, however, that many recent taxonomic studies regard the presence of allopatric populations as an indication that speciation has occurred. We suggest that stronger evidence is needed to show that populations are sufficiently distinct to merit specific status. This evidence should be capable of discriminating genuine ecological and evolutionary distinctiveness from minor differences that could result from geographic isolation.

I am not going into the various species concepts here but the taxonomists who do such splitting rely on using genetic analyses to identify different lineages. Some—the ‘splitters’—then argue that if groups of animals show distinct genetic lineage then they should be treated as different species, regardless of the fact that morphological differences are minor or that members of one lineage recognised those of anther as being of the same kind and would breed with them if given the chance and do do so in captivity.

While ‘new’ species may at first sight be an attractive proposition for those seeking the input of conservation resources, Meiri & Mace argued that with limited funding, resources could be diverted from a really important projects and that splitting species does not necessarily have conservation value. They also supported the policy of supporting species ‘across their ranges, perhaps favoring phenotypically distinct populations or geographically isolated subsets so as to fully conserve variation’.

Have those lessons so well spelt out by Meiri and Mace been learnt? Was madam right about Thorncroft’s giraffe?

Meiri S, Mace GM. 2007. New taxonomy and the origin of species. PLoS Biol 5(7): e194. doi:10.1371/journal.pbio.0050194