Calibrating phylogenetic trees is a difficult problem for data with a patchy taxonomic sampling and markers with heterogeneous patterns of molecular evolution.
First, it is difficult to see how saturated markers and patchy cohorts within sampling locations could generate statistically significant patterns of IBD over the whole distributional range [ 39].
Finally, Maes et al. [ 34] suggested that, given the random factors affecting spawning success in the open ocean, a sweepstake strategy [ 56] might explain genetically patchy recruitment in sampling locations across Europe [ 57], leading to a weak but significant isolation-by-time (IBT) signal.
Although, VA may be patchy and biopsy samples without atrophy may be misinterpreted as atrophic by the pathologist if the samples are wrongly oriented, earlier validation has shown that the vast majority (90%) of intestinal biopsies with VA are correctly classified by Swedish pathologists (Table 3).
The coccoids (∼0.5 to 2 μm diameter) were present both in chains and individually throughout the silica- and iron-rich bands, while the filamentous remnants (∼1 3 μm diameter, and up to 200 μm length) were localized and patchy in the sample.
Four biopsy specimens were excluded from further analysis according to the pre--specified exclusion criteria: (1) extremes of patchy fibrosis (n=2); (2) sample too superficial and included mainly endocardial tissue (n=2).
"Sampling a patchy environment, you may not necessarily hit the patches," he said.
Since benthic microalgal distribution can be patchy, we used composite samples to increase the likelihood that the benthic chl a concentrations represented the entire surface sediment in each mesocosm tank.
The observation of a bryozoan morphotype in one of our Urania samples suggests patchy distributions of this ctenostome taxon.
Another consideration is that Hp bacterial density may be patchy, and only using samples from the gastric antrum may be inadequate.
