RESUMEN
PREMISE OF THE STUDY: Leaf area is a key trait that links plant form, function, and environment. Measures of leaf area can be biased because leaf area is often estimated from dried or fossilized specimens that have shrunk by an unknown amount. We tested the common assumption that this shrinkage is negligible. METHODS: We measured shrinkage by comparing dry and fresh leaf area in 3401 leaves of 380 temperate and tropical species and used phylogenetic and trait-based approaches to determine predictors of this shrinkage. We also tested the effects of rehydration and simulated fossilization on shrinkage in four species. KEY RESULTS: We found that dried leaves shrink in area by an average of 22% and a maximum of 82%. Shrinkage in dried leaves can be predicted by multiple morphological traits with a standard deviation of 7.8%. We also found that mud burial, a proxy for compression fossilization, caused negligible shrinkage, and that rehydration, a potential treatment of dried herbarium specimens, eliminated shrinkage. CONCLUSIONS: Our findings indicate that the amount of shrinkage is driven by variation in leaf area, leaf thickness, evergreenness, and woodiness and can be reversed by rehydration. The amount of shrinkage may also be a useful trait related to ecologically and physiological differences in drought tolerance and plant life history.
Asunto(s)
Clima , Hojas de la Planta/anatomía & histología , Hojas de la Planta/fisiología , Investigación/normas , Sesgo , Ecología , Magnoliopsida/anatomía & histología , Magnoliopsida/clasificación , Magnoliopsida/fisiología , Modelos Biológicos , Hojas de la Planta/efectos de los fármacos , Especificidad de la Especie , Agua/farmacologíaRESUMEN
We have reviewed records for patients under 2 years of age who presented at our hospital with mild closed head injuries and nondisplaced skull fractures, specifically to examine methods utilized for spine clearance, associated cervical injuries, involvement and findings of child protective services and delayed complications. Of 42 patients included in the series, none were found to have cervical spine injuries. Child protective services were involved in 12 cases with confirmatory findings and subsequent placement occurring in 2 cases. There were no serious delayed complications in this series of patients. AP and lateral plain films of the cervical spine are nonetheless recommended until larger prospective studies suggest otherwise.