Evolutionary theory and empirical studies suggest that many animals, including humans, have a genetic predisposition to acquire and retain property This is hardly surprising because survival is closely bound up with the acquisition of things: food, shelter, tools and territory But the root of these general urges may also run to quite specific and detailed rules about property acquisition, retention and disposition The great variation in property-related behaviours across species may mask some important commonalities grounded in adaptive utility Experiments and observations in the field and laboratory suggest that the legal rules of temporal priority and possession are grounded in what were evolutionarily stable strategies in the ancestral environment Moreover, the preferences that humans exhibit in disposing of their property on their deaths, both by dispositions made in wills and by the laws of intestacy, tend to advance reproductive success as a result of inclusive fitness pay-offs

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The property 'instinct'.

In international relations, unlike the natural sciences, there are few fundamental principles or laws. The world map, however, reveals at least one iron law of global politics: human territoriality. Almost every inch of the globe is partitioned into exclusive and bounded spaces that “belong” to specific groups of humans. Any that is not—such as Kashmir, Jerusalem, and the South China Sea—remains hotly contested. Throughout history, territory has led to recurrent and severe conflict. States are prepared to go to war, and individuals are prepared to die, even over land with little intrinsic value. While such behavior presents a puzzle for international relations theory, a broader evolutionary perspective reveals that territorial behavior has the following three characteristics: (1) it is common across the animal kingdom, suggesting a convergent solution to a common strategic problem; (2) it is a dominant strategy in the “hawk-dove” game of evolutionary game theory (under certain well-defined conditions); an...

Grounds for War: The Evolution of Territorial Conflict

Influence of physical stress, distress cues, and predator kairomones on the foraging behavior of Ozark zigzag salamanders, Plethodon angusticlavius

Parasites have been shown to impair the behaviour of their hosts, compromising the host's ability to exploit and compete for resources. We conducted two experiments to determine whether infestation with an ectoparasitic mite (Hannemania eltoni) was associated with changes in aggressive and foraging behaviour in the Ozark zigzag salamander, Plethodon angusticlavius. In a first experiment, male salamanders with high parasite loads were less aggressive overall than males with low parasite loads during territorial disputes. In addition, males with high parasite loads were more aggressive toward opponents with high parasite loads (symmetric contests) than toward opponents with low parasite loads (asymmetric contests). In contrast, males with low parasite loads did not adjust their level of aggression according to the parasite load of the opponent. In a second experiment, foraging behaviour of females was tested in response to ‘familiar’ (Drosophila) prey and ‘novel’ (termite) prey. Latency to first capture was significantly longer for parasitized than non-parasitized females when tested with ‘familiar’ prey, but not for ‘novel’ prey. Our results suggest that parasite-mediated effects may have profound influences on individual fitness in nature.

Parasitized Salamanders are Inferior Competitors for Territories and Food Resources

We used radio-telemetry data (28,560 positional fixes) collected on 153 black-footed ferrets (Mustela nigripes) to (1) reexamine the assumed obligate relationship of these ferrets to prairie dogs (Cynomys spp.), (2) investigate habitat preferences of ferrets at a small scale ( 1 year (P = 0.048). Also, preference was stronger for wild-born young ferrets than for young captive-born ferrets released to augment the wild population (P = 0.040). This additional evidence for competition among ferrets, and for an advantage of prior residency, raises conservation concerns. The energetics-based model commonly used to predict ferret densities at reintroduction sites does not consider competition, which likely leads to overestimation of the densities of ferrets attainable in high-quality habitat. During sequential releases of ferrets, prior residency may handicap success of newcomers, even though the latter may have higher potential fitness. Although the manner of initial colonization of available habitat by blackfooted ferrets, and their subsequent competition for it, was suggestive of an ideal despotic distribution, we did not assess effects of prey density or burrow density on fitness.

Habitat preferences and intraspecific competition in black-footed ferrets

Once territories become established residents often have a high probability of successfully defending their territories against intruders. This advantage often can be explained by intrinsic qualities (e.g., size, body condition, experience) that make residents superior competitors. In addition, residency status can confer an advantage that is independent of fighting ability. We used a laboratory experiment to examine the effect of residency status on aggressive behavior by adults of the Ozark zigzag salamander (Plethodon angusticlavius), a small terrestrial salamander found under rocks and logs on the forest floor. We controlled for intrinsic effects by testing each individual as both a resident and an intruder in random order. Males and females were tested in same-sex contests in separate experiments. Based on an index that incorporated the frequency of aggressive and submissive postures, both males and females were significantly more aggressive as residents than as intruders. Bites were perform...

Kimberly A. Medley

Papers

The Influence of Residency Status on Agonistic Behavior of Male and Female Ozark Zigzag Salamanders Plethodon angusticlavius