Interpretation of Plasma Selenium Data in Huemul: Response to Flueck et al

Osteopathology and selenium deficiency co-occurring in a population of endangered Patagonian huemul (Hippocamelus bisulcus)

“…The alternative interpretation [ 23 ] of the first-ever study on Se status in huemul from RNLC related to the conclusion by Chihuailaf et al [ 22 ] that “Se values were within the interval reported for white-tailed deer”, and that Se concentrations from huemul were “within reference intervals calculated for other deer”, referring to the study by [ 24 ]. However, the review by [ 24 ] was not based on data from deer “in one area” as asserted by Chihuailaf and Corti [ 44 ], but provided results from 8 different populations with means differing by up to 542%. These results certainly cannot serve as reference intervals, but mainly because [ 24 ] mentioned deer and livestock in their study areas as having been diagnosed with white muscle disease, and 50% of the deer were severely deficient and 75% had less than the critical concentration by livestock standards.…”

“…More importantly, we questioned the removal of 36% of data points from the analysis by [ 22 ], based on the claim that these were outliers. In response, Chihuailaf and Corti [ 44 ] only mention that Friedrichs et al [ 45 ] suggest the removal of outliers to minimize error when establishing reference intervals. However, according to Friedrichs et al definition of outliers we must ask: were these eliminated data points considered not to belong to the underlying distribution of the overall data set?…”

“…Chihuailaf and Corti [ 44 ] further suggested that “North America, where acid rain produces soils low in selenium”, would be problematic for their wildlife, as opposed to southern South America which “lacks chronic atmospheric pollution”. This assertion does not hold up, first because only limited parts of North America with low soil Se are impacted by acid rain.…”

“…The argument that huemul have survived since the Pleistocene in habitats dominated by volcanic soils lacking in Se [ 44 ] needs qualification. First, during glaciation events, including the last glacial maximum, the area of the remaining extant huemul groups was under an ice cap reaching 1,800 m in thickness.…”