Data from: X-ray computed tomography and its potential in ecological research: a review of studies and optimization of specimen preparation

Imaging techniques are a cornerstone of contemporary biology. Over the
last decades, advances in micro-scale imaging techniques have allowed
fascinating new insights into cell and tissue morphology and internal
anatomy of organisms across kingdoms. However, most studies so far
provided snapshots of given reference taxa, describing organs and tissues
under “idealized” conditions. Surprisingly, there is an almost complete
lack of studies investigating how an organism´s internal morphology
changes in response to environmental drivers. Consequently, ecology as a
scientific discipline has so far almost neglected the possibilities
arising from modern micro-scale imaging techniques. Here, we provide an
overview of recent developments of x-ray computed tomography as an
affordable, simple method of high spatial resolution, allowing insights
into three-dimensional anatomy both in vivo and ex vivo. We review
ecological studies using this technique to investigate the
three-dimensional internal structure of organisms. In addition, we provide
practical comparisons between different preparation techniques for maximum
contrast and tissue differentiation. In particular, we consider the novel
modality of phase contrast by self-interference of the x-ray wave behind
an object (i.e. phase contrast by free space propagation). Using the
cricket Acheta domesticus (L.) as model organism, we found that the
combination of FAE fixative and iodine staining provided the best results
across different tissues. The drying technique also affected contrast and
prevented artefacts in specific cases. Overall, we found that for the
interests of ecological studies, x-ray computed tomography is useful when
the tissue or structure of interest has sufficient contrast that allows
for an automatic or semi-automatic segmentation. In particular, we show
that reconstruction schemes which exploit phase contrast can yield
enhanced image quality. Combined with suitable specimen preparation and
automated analysis, x-ray CT can therefore become a promising quantitative
3D imaging technique to study organisms´ responses to environmental
drivers, in both ecology and evolution.