Welcome to the Jimenez Lab!
Comparative Animal Physiology

Animal life-history traits fall within limited ecological space, a continuum referred to as a “slow-fast” life-history axis. Differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Dogs seem to be an anomaly to the typical correlations within this life-history trade-offs, with smaller dogs having higher metabolic rates and longer lives compared with larger dogs. Thus, dogs provide a unique system to examine physiological consequences of life-history trade-offs. For example, small dogs tend to have longer lifespans, fewer pups per litter, faster but shorter growth trajectories, higher metabolic rates and, in general, larger metabolically active organs compared with large dogs.  The mechanistic and metabolic consequences, at the cellular level, of this seemingly contradictory relationship between body mass and lifespan in this species has not been previously addressed. Our lab is now mostly focused on addressing questions related to this model system.

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There is ample evidence that the earth is warming, likely as a result of anthropomorphic activity. Because of this, we have the critical task to identify the characteristics of species that make them either resilient or susceptible to increases in their natural thermal regime. Birds are important bio-indicators of detrimental effects of global climate change. Temperatures not only affect the metabolic rate of birds, but also exert other indirect and direct effects on their behavioral patterns. These effects include earlier breeding, changes in timing of migration, reduction in egg size, lowered breeding success, alterations in population sizes, and changes in population distributions. The implications of climate change for birds have only recently begun to be addressed and there is already compelling evidence some of these animals have been affected by recent climate change. Using this study model, we now seek to focus on questions related to the impacts of thermal physiology on a bird's whole-animal physiology.

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Our lab's current National Science Foundation (NSF) grant addresses "Costs and Trade-offs of Phenotypically Flexible Responses to Winter Temperature Variability in Birds" in collaboration with Dr. Yufeng Zhang, and Dr. David Swanson.