SPECIMENS CAN BE USED IN CONSERVATION
Some people, even university administrators, have questioned the value of maintaining scientific collections in museums. Others view such thinking as shallow. Museums serve as repositories for fossils and recently extinct species as well as common, widely distributed forms, all permanently stored for scientific study. From the standpoint of advancing our knowledge, such a database is critical. Examining biological representatives of past and present species can provide an overview of natural or human-caused change across time and space. A recently published study provides evidence that museums are valuable in yet another way.
Taking an unusual approach to addressing the worldwide decline in reptile species, Robert N. Reed and Richard Shine of the University of Sydney examined 18,000 museum specimens of Australian snakes in the cobra family. The scientists set out to answer a specific question. Why do some species decline rapidly in response to human disturbance whereas others readily exploit disturbed habitats and may actually thrive?
A pressing issue in conservation biology is identifying causes for the global decline in numbers of many groups of animals and plants. Some reasons are obvious: replacing a wetland or forest with parking lots and buildings assures the permanent destruction of native wildlife in that area. Overcollecting a rare plant, such as certain orchids, restricted to a small area can result in annihilation of the population. Polluting a river with toxic chemicals is clearly detrimental to the local fauna and flora. A more difficult task is to ascertain basic, underlying traits that declining species in a group have in common--traits that make them more susceptible to environmental alteration.
Reed and Shine set out to identify ecological factors that could be used to predict how vulnerable any given species of snake was likely to be. The conservation status of most snakes is poorly understood, due to negative public attitudes toward snakes that result in limited funding for inventory and research. In addition, the secretive nature of snakes makes ecological study of them difficult. Hence, verifying that snake populations are declining in a region can be difficult. In Australia, experts had identified approximately a dozen snake species as being of conservation concern. For Reed and Shine, the logical next step was to examine museum specimens and identify traits that were common among threatened species.
With most animals, typical factors associated with endangerment are large body size, low number of offspring, and specialization for particular habitats or diets. Thus giant pandas are the quintessential endangered species: they meet all the traditional qualifications. But based on the study of museum specimens, most of these criteria were judged to be inapplicable to Australian snakes.
Instead, threatened species of snakes were characterized by two primary traits, one related to how they obtained their food; the other, to their mating system. Threatened species were generally ambush predators, meaning they lie in wait, usually camouflaged, until their prey come to where they are. Nonthreatened species were more likely to be active foragers that cover large areas in search of prey. One explanation offered for this relationship between foraging mode and endangerment is that ambush predators do not move long distances in search of prey. Therefore, they may be more dramatically affected when prey densities are reduced by habitat degradation.
regard to the type of mating system, nonthreatened Australian snake
species were more likely to be those in which males engage in combat
with each other during the mating season. Threatened species were less
likely to be those with male combat rituals. In species without male-male
combat, females get appreciably larger; hence they may be more obvious,
and therefore more vulnerable, to mortality by humans. Once humans alter
habitats where snakes live, the added impact of removal of large, reproducing
females may result in further declines of a species.