Sex Differences in Aggression: Female Hermit Crabs Initiate Few Fights against Males and Lose Most of Those.

AbstractIndividuals with similar biological requirements frequently compete for resources. Males and females have evolved different reproductive strategies in which females invest more in fecundity and males in intrasexual competition for mates. Although less common than within-sex competition, intersexual contests may occur to obtain resources.

Physiological thermal responses of three Mexican snakes with distinct lifestyles.

The impact of temperature on reptile physiology has been examined through two main parameters: locomotor performance and metabolic rates. Among reptiles, different species may respond to environmental temperatures in distinct ways, depending on their thermal sensitivity. Such variation can be linked to the ecological lifestyle of the species and needs to be taken into consideration when assessing the thermal influence on physiology.

Flexibility in thermal requirements: a comparative analysis of the wide-spread lizard genus Sceloporus.

Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness, especially in ectotherms, which rely heavily on environmental temperatures for thermoregulation. Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change. The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats.

Avoiding the effects of translocation on the estimates of the metabolic rates across an elevational gradient.

Body maintenance costs are often considered a proxy for performance in fitness traits. Maintenance energy requirements are measured as minimal metabolic rate of inactive, postabsorptive individuals in the laboratory. For mountain-dwelling species, translocation to the laboratory often means that they are also moved to another elevation.

Resting metabolic rates increase with elevation in a mountain-dwelling lizard.

Individuals that inhabit broad elevational ranges may experience unique environmental challenges. Because temperature decreases with increased elevation, the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort. The resting metabolic rate (RMR) of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits.

Feeling the heat: Extreme temperatures compromise constitutive innate humoral immunity and skin color in a desert dwelling lizard.

Environmental temperature, particularly in habitats with extreme temperature fluctuations, may shape selection pressures on life history traits. Especially in ectotherms, temperature affects performance, physiology, and in some species, skin color. Skin color can be a sexual ornament signaling the bearer's ability to resist infections, when only high-quality individuals are able to invest both in high immune defense and elaborate ornament expression.

Environmental temperature alters the overall digestive energetics and differentially affects dietary protein and lipid use in a lizard.

Processing food (e.g. ingestion, digestion, assimilation) requires energy referred to as specific dynamic action (SDA) and is at least partially fuelled by oxidation of the nutrients (e.