PubMed · 14783485
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S BACHI. 1950. [Does adaptation tonsillitis exist?].. https://pubmed.ncbi.nlm.nih.gov/14783485/
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Understanding the genetic bases and modes of adaptation to current climatic conditions is essential to accurately predict responses to future environmental change. We conducted a genome-wide scan to identify climate-adaptive genetic loci and pathways in the plant Arabidopsis thaliana. Amino acid-changing variants were significantly enriched among the loci strongly correlated with climate, suggesting that our scan effectively detects adaptive alleles. Moreover, from our results, we successfully predicted relative fitness among a set of geographically diverse A. thaliana accessions when grown together in a common environment. Our results provide a set of candidates for dissecting the molecular bases of climate adaptations, as well as insights about the prevalence of selective sweeps, which has implications for predicting the rate of adaptation.
Intermittent hypoxia (IH) induces alterations in respiratory control that reflect various types of ventilatory plasticity. In freely behaving rats, acute exposure to IH elicits enhancements in normoxic minute ventilation (VE), termed ventilatory long-term facilitation. Exposure to longer time periods of IH induces unique ventilatory adaptations to intermittent hypoxia (VAIH). We hypothesized that long-term IH-induced ventilatory plasticity may be developmentally regulated and thus, IH exposures at progressively later post-natal ages may elicit differential effects on the magnitude of VAIH. To examine this issue, male Sprague-Dawley rats were exposed to 30 continuous days of IH beginning at post-natal ages 1, 10, 30, 60, 180, 360, and 540 days. Control animals were exposed to normoxic conditions with room air. Normoxic VE was significantly higher in IH-exposed rats (p < 0.01) except for the group in which IH was initiated at post-natal age 540 days (p = NS). The magnitude of VAIH was greatest in rats exposed in the immediate post-natal period and gradually diminished with advancing post-natal age. Enhanced normoxic VE was due to significant contributions from both frequency (p < 0.01) and tidal volume (p < 0.01), and could not be accounted for by changes in metabolic rate. We conclude that the magnitude of IH-induced ventilatory plasticity is age-dependent with progressive declines becoming apparent with advancing post-natal age.
Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment by regulating their body temperature and by modifying physiological and biochemical rates. Phenotypic flexibility (reversible phenotypic plasticity, acclimation, or acclimatisation in rate functions occurs in all major taxonomic groups and may be considered as an ancestral condition. Within the Reptilia, representatives from all major groups show phenotypic flexibility in response to long-term or chronic changes in the thermal environment. Acclimation or acclimatisation in reptiles are most commonly assessed by measuring whole animal responses such as oxygen consumption, but whole animal responses are comprised of variation in individual traits such as enzyme activities, hormone expression, and cardiovascular functions. The challenge now lies in connecting the changes in the components to the functioning of the whole animal and its fitness. Experimental designs in research on reptilian thermal physiology should incorporate the capacity for reversible phenotypic plasticity as a null-hypothesis, because the significance of differential body temperature-performance relationships (thermal reaction norms) between individuals, populations, or species cannot be assessed without testing that null-hypothesis.