Effects of consumer preferences for rarity on the harvest of wild populations within a species

Abstract

Economic theory predicts that exploitation of a species alone is unlikely to result in extinction because of escalating costs involved in finding increasingly rare individuals of a declining species. However, a recently proposed hypothesis, the Anthropogenic Allee Effect (AAE), proposes that if people place disproportionate value on rare species, this may result in a cycle whereby increased exploitation reduces the population size, thus increasing its value and ultimately leading to its extinction in the wild. We tested this hypothesis using data collected on wild harvests, preferences of pet keepers and sale prices of different populations of green pythons (Morelia viridis) and hypothesized that the AAE could occur among population within species, not just between them. The rarity of populations of green pythons was strongly positively correlated with price and negatively correlated with harvest levels. The two populations that were deemed most desirable by pet collectors exhibited abnormal coloration and were found to be suffering from the effects of over-exploitation for the pet trade. Adequate regulation and enforcement are needed to reduce the effects of demand on illegal harvesting and conservationists and government bodies should be aware of the effects of disclosing the rarity of a species and its populations.