Dispersal-induced social stress prolongs gestation in wild meerkats.

In the majority of mammals, gestation length is relatively consistent and seldom varies by more than 3%. In a few species, females can adjust gestation length by delaying the development of the embryo after implantation. Delays in embryonic development allow females to defer the rising energetic costs of gestation when conditions are unfavourable, reducing the risk of embryo loss. Dispersal in mammals that breed cooperatively is a period when food intake is likely to be suppressed and stress levels are likely to be high. Here, we show that pregnant dispersing meerkats (Suricata suricatta), which have been aggressively evicted from their natal group and experience weight loss and extended periods of social stress, prolong their gestation by means of delayed embryonic development. Repeated ultrasound scans of wild, unanaesthetized females throughout their pregnancies showed that pregnancies of dispersers were on average 6.3% longer and more variable in length (52-65 days) than those of residents (54-56 days). The variation in dispersers shows that, unlike most mammals, meerkats can adapt to stress by adjusting their pregnancy length by up to 25%. By doing so, they potentially rearrange the costs of gestation during adverse conditions of dispersal and enhance offspring survival.

Potential for climate effects on the size-structure of host-parasitoid indirect interaction networks.

Communities of insect herbivores are thought to be structured mainly by indirect processes mediated by shared natural enemies, such as apparent competition. In host-parasitoid interaction networks, overlap in natural enemy communities between any pair of host species depends on the realized niches of parasitoids, which ultimately depend on the foraging decisions of individuals. Optimal foraging theory predicts that egg-limited parasitoid females should reject small hosts in favour of future opportunities to oviposit in larger hosts, while time-limited parasitoids are expected to optimize oviposition rate regardless of host size. The degree to which parasitoids are time- or egg-limited depends in part on weather conditions, as this determines the proportion of an individual's lifespan that is available to foraging. Using a 10-year time series of monthly quantitative host-parasitoid webs, we present evidence for host-size-based electivity and sex allocation in the common secondary parasitoid Asaphes vulgaris. We argue that this electivity leads to body-size-dependent asymmetry in apparent competition among hosts and we discuss how changing weather patterns, as a result of climate change, may impact foraging behaviour and thereby the size-structure and dynamics of host-parasitoid indirect interaction networks.

Local anesthesia in hair transplantation.

BACKGROUND: Safe and effective use of local anesthesia is essential in hair transplantation. OBJECTIVE: To review the agents and techniques of local anesthesia as applied to hair transplantation. METHODS: Information was retrieved from texts, journal articles found by MEDLINE searches, and related references. RESULTS: Agents, vasoconstrictors, maximum dosages, toxicity, and techniques are discussed. CONCLUSION: Effective local anesthesia can be maintained throughout hair transplantation. Care must be exercised to minimize discomfort through proper technique and to minimize toxicity through judicious use of vasoconstrictors and nerve blocks and by monitoring total dosage. Constant monitoring for toxicity is required, as is early intervention in the unlikely event that warning signs should appear.