A team led by ecologist Pieter Johnson found that only a trematode called Ribeiroia that burrows into tadpoles' limbs seems to cause the range of malformations seen in the field, although chemicals may make frogs more vulnerable to the worm (ScienceNOW, 29 April 1999, 12 July 2002).
However, whether these mutations are sufficiently severe to cause the range of aging effects has been questioned [ 24].
There was a suggestion that certain socioeconomic factors, most notably leaving fulltime education at age 19+, caused the range of scale values to widen, leaving attribute impacts unchanged.
Second, it is possible that changes in environmental factors, such as climate, might cause the ranges of both species to move in the same direction, thus also causing the hybrid zone to move [e.g., 12].
Therefore we can conclude that there could indeed be a large inter-individual variation causing the broad range of baseline BPND values.
But Ruiz-Carrascal's team is finding evidence that the circulation patterns that deliver this moisture are changing, causing the upper ranges of the tropical Andes to warm up and dry out very quickly.
The scaled contraction of g(t - τ, σ) causes the relevant range of τ to become more localised around t as f increases.
One of the prominent theories of ADHD proposes that a core deficit of response inhibition underlies the development of broader deficits in executive function, which in turn cause the wide range of dysfunctional behaviours in ADHD [ 12].
"As with similar ophthalmic incident clusters there is no clear single cause for the range of problems our patients appear to have experienced.
Climatic cooling and drying that began about 65.5 million years ago and continued throughout the Cenozoic Era caused the geographic range of the dawn redwood to contract to its present relic distribution.
