reproductive success, family size, home range size, patterns of association with conspecifics, and even parasite load (Boydston and others 2003; Engh and others 2003; Holekamp and others 1996, 1997a).
Most scientists work on animals in the laboratory rather than in the wild precisely to minimize the kind of variation I have described herein. Then why worry about it? My response is that naturally occurring variation is important to those regulating laboratory animal care because this variation suggests that even for a single species there is often likely to be an entire range of conditions under which the species will thrive in the laboratory.
In summary, classical ethology and modern behavioral ecology have taught us that every animal comes into the laboratory with an evolutionary past and a set of traits shaped by natural selection. These include an Umwelt, a normal repertoire of behaviors, and an ability to survive and reproduce under a range of conditions. These traits should factor into our decision making about laboratory animal care guidelines. Given the diversity of conditions under which most species exist in nature, it seems reasonable to expect that a heterogeneous array of husbandry conditions can be utilized in the laboratory without compromising our ability to maintain a homogeneous set of ethical standards for the treatment of these animals.
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