these traits are often substantial [e.g., Coltman et al. (2003)]. Garel et al. (2007) found similar patterns in morphology and life history resulting from trophy ram hunting in Europe.
Understanding the response of consumers and hunters to perceived rarity is vital for predicting the impact of intervention strategies that seek to minimize extinction risk.
Hall et al. (2008)
Another human activity that can impose exploitative selection on wild populations is specimen collecting, whether for private, commercial, or scientific use. The actions of collectors, which most commonly target vertebrates, such as tropical fishes, and invertebrates, such as arthropods and gastropods, could impose selection on wild populations through the removal of specimens conspicuous by their large size and appearance. Such selection is likely to be effective when populations are rare, phenotypes are dramatic, and opportunity for harvest by humans is substantial. Highly selective collection practices could affect the sustainability of these trades and the conservation of rare species (Slone et al., 1997; Hall et al., 2008).
Terrestrial snails are one of the most imperiled groups in the world, and overcollecting has been one of the major threats to many of these species. For example, collecting of live tree snails (Liguus and Orthicalus spp.) found on isolated hardwood hammocks in the Florida Everglades began in the early 19th century and peaked in the 1940s before regulations were enacted because of conservation concerns (Humes, 1965). The loss of prized forms led collectors to translocate valuable morphs to places unknown to other snail collectors (Humes, 1965). In addition, collection of especially attractive morphs was competitive so that some attractive morphs were purposefully overcollected because they were more valuable when they became rare. Similarly, major snail collecting took place in the late 19th and early 20th centuries in Hawaii, focusing on the brightly colored and variable Achatinellinae tree snails. Overcollecting did lead to extinctions, but it is unknown if there was any differential selective effects on morphs (Hadfield, 1986). In Moldova, Andreev (2006) compared land snail (Helix pomatia) characteristics from exploited and unexploited sites and found that sites where land snails were exploited for food had much lower densities and a higher proportion of adult snails than sites that were not exploited. Specimen collecting can therefore provide an opportunity for selection that might reduce population viability.