Variation in courtship rate in the fiddler crab Uca annulipes: is it related to male attractiveness?

We investigated among-male variation in courtship waving inthe fiddler crab Uca annulipes. Wave rate is positively correlatedwith both male carapace size and relative claw size (controlledfor body size), and relative claw size is positively correlatedwith an index of body condition. An experimental reduction inthe availability of food decreased male wave rate. These datasuggest that some of the variation in wave rate among malesis due to variation in male condition combined with energeticcosts to waving (differential costs). However, we also foundthat the correlation between male size and wave rate decreasedover the semilunar cycle. Later in the cycle, smaller malesincrease their wave rate relative to that of larger males. Previouswork has shown that females are more likely to accept a smallermale as a mate later in the cycle. We suggest that smaller malesinvest disproportionately more in courtship later in the cyclebecause the potential benefits are greater due to their increasedattractiveness to females (differential benefits). Alternativeexplanations for the observed temporal trend are also discussed.     

GABA transporters inDrosophila melanogaster: molecular cloning, behavior, and physiology

Molecular cloning of GABA transporter-homologous cDNAs from aDrosophila melanogaster headspecific library was accomplished using a conserved oligomer from a highly conserved domain within the mammalian GABA transporters. Partial DNA sequencing of these cDNAs demonstrated homology with the mammalian transporters, indicating these are ancient, evolutionarily conserved molecules. Although theDrosophila cDNAs had distinct restriction enzyme patterns, they recognized the same locus inDrosophila genomic DNA, suggesting that the multiple isoforms might arise via alternative splicing. Antibodies specific for the mammalian GABA transporters GAT1, GAT2 and GAT3 recognized non-overlapping and developmentally distinct patterns of expression inDrosophila neuronal tissues. Treatment of larval instars with nipecotic acid, a generalized GABA reuptake inhibitor, revealed specific, dose-dependent alterations in behavior consistent with the presence of multiple transporter molecules with differing affinities for this drug. Synaptic current recordings revealed that nipecotic acid treated larvae have an increase in latency jitter of evoked quantal release, resulting in a broader average excitatory junctional current which was manifested in a broader EJP. These results imply that alterations in the development of the CNS occur if GABAergic neurotransmission is protentiated during development. The data suggest that, as in mammals, there are multiple GABA transporters inDrosophila whose expression is differentially regulated.     

Strategies and counterstrategies to infanticide in mammals

I analyse and summarize the empirical evidence in mammals supporting alternative benefits that individuals may accrue when committing nonparental infanticide. Nonparental infanticide may provide the perpetrator with nutritional benefits, increased access to limited resources, increased reproductive opportunities, or it may prevent misdirecting parental care to unrelated offspring. The possibility that infanticide is either a neutral or maladaptive behaviour also is considered. I devote the second half of this article to reviewing potential mechanisms that individuals may use to prevent infanticide. These counterstrategies include the early termination of pregnancy, direct aggression by the mother against intruders, the formation of coalitions for group defence, the avoidance of infanticidal conspecifics, female promiscuity, and territoriality. I evaluate the support for each benefit and counterstrategy across different groups of mammals and make suggestions for future research.     

On the Evolution of Behavioral Heterogeneity in Individuals and Populations

A wide range of ecological and evolutionary models predict variety in phenotype or behavior when a population is at equilibrium. This heterogeneity can be realized in different ways. For example, it can be realized through a complex population of individuals exhibiting different simple behaviors, or through a simple population of individuals exhibiting complex, varying behaviors. In some theoretical frameworks these different realizations are treated as equivalent, but natural selection distinguishes between these two alternatives in subtle ways. By investigating an increasingly complex series of models, from a simple fluctuating selection model up to a finite population hawk/dove game, we explore the selective pressures which discriminate between pure strategists, mixed at the population level, and individual mixed strategists. Our analysis reveals some important limitations to the ESS framework often employed to investigate the evolution of complex behavior.     

Good genes, old age and life-history trade-offs

The possibility of using old age of a mate as an indicator of genetic quality is currently controversial. Early verbal models as well as a recent simulation study noted that female choice for old mates is beneficial because longevity indicates viability in the current environment. In contrast, a quantitative genetic model of the relationship between age and breeding value of fitness casts strong doubts on the mechanism. The present analysis shows, however, that these doubts are mainly the result of assuming that all variation among individuals arises from differences in allocation between components of fitness. This neglects the possibility of variability in condition as a whole. Instead, when allowing for persistent variability in condition and assuming optimal reaction norms in allocation, it is shown that correlations between survival and genetic quality or fitness can easily be established at all ages. On the other hand, the results also suggest that the validity of verbal arguments is limited, and counterexamples can be generated where low-quality individuals should invest more in survival. Therefore, resolution of the old age indicator problem requires specification of the constraints acting on life-history characteristics.     

Energetic costs of territorial boundary patrols by wild chimpanzees

Chimpanzees are well known for their territorial behavior. Males who belong to the same community routinely patrol their territories, occasionally making deep incursions into those of their neighbors. Male chimpanzees may obtain several fitness benefits by participating in territorial boundary patrols, but patrolling is also likely to involve fitness costs. Patrollers risk injury or even death, and patrols may be energetically costly and may involve opportunity costs. Although territorial patrols have been reported at all long‐term chimpanzee study sites, quantitative data on their energetic costs have not previously been available. I evaluated the energy costs of patrolling for male chimpanzees at Ngogo, Kibale National Park, Uganda during 14 months of observation. In 29 patrols and matched control periods, I recorded the distances covered and time spent traveling and feeding by chimpanzees. I found that male chimpanzees covered longer distances, spent more time traveling, and spent less time feeding during patrols than during control periods. These results support the hypothesis that chimpanzees incur energetic costs while patrolling and suggest that ecological factors may constrain the ability of chimpanzees to patrol. Am. J. Primatol. 72:93–103, 2010. © 2009 Wiley‐Liss, Inc.