Phenotypic evolution in a fossil gastropod species lineage: evidence for adaptive radiation?

Detecting speciation in the fossil record is a particularly challenging matter. Palaeontologists are usually confronted with poor preservation and limited knowledge on the palaeoenvironment. Even in the contrary case of adequate preservation and information, the linkage of pattern to process is often obscured by insufficient temporal resolution. Consequently, reliable documentations of speciation in fossils with discussions on underlying mechanisms are rare. Here we present a well-resolved pattern of morphological evolution in a fossil species lineage of the gastropod Melanopsis in the long-lived Lake Pannon. These developments are related to environmental changes, documented by isotope and stratigraphical data. After a long period of stasis, the ancestral species experiences a phenotypic change expressed as shift and expansion of the morphospace. The appearance of several new phenotypes along with changes in the environment is interpreted as adaptive radiation. Lake-level high stands affect distribution and availability of habitats and, as a result of varied functional demands on shell geometry, the distribution of phenotypes. The on-going divergence of the morphospace into two branches argues for increasing reproductive isolation, consistent with the model of ecological speciation. In the latest phase, however, progressively unstable conditions restrict availability of niches, allowing survival of one branch only.

Benthic cover map of Heron Reef derived from a high-spatial-resolution multi-spectral satellite image using object based image analysis

Providing accurate maps of coral reefs where the spatial scale and labels of the mapped features correspond to map units appropriate for examining biological and geomorphic structures and processes is a major challenge for remote sensing. The objective of this work is to assess the accuracy and relevance of the process used to derive geomorphic zone and benthic community zone maps for three western Pacific coral reefs produced from multi-scale, object-based image analysis (OBIA) of high-spatial-resolution multi-spectral images, guided by field survey data. Three Quickbird-2 multi-spectral data sets from reefs in Australia, Palau and Fiji and georeferenced field photographs were used in a multi-scale segmentation and object-based image classification to map geomorphic zones and benthic community zones. A per-pixel approach was also tested for mapping benthic community zones. Validation of the maps and comparison to past approaches indicated the multi-scale OBIA process enabled field data, operator field experience and a conceptual hierarchical model of the coral reef environment to be linked to provide output maps at geomorphic zone and benthic community scales on coral reefs. The OBIA mapping accuracies were comparable with previously published work using other methods; however, the classes mapped were matched to a predetermined set of features on the reef.

Revised age model of DSDP Site 95-612

Alkenone-based Cenozoic records of the partial pressure of atmospheric carbon dioxide (pCO2) are founded on the carbon isotope fractionation that occurred during marine photosynthesis (epsilon [p37:2]). However, the magnitude of epsilon [p37:2] is also influenced by phytoplankton cell size - a consideration lacking in previous alkenone-based CO2 estimates. In this study, we reconstruct cell size trends in ancient alkenone-producing coccolithophores (the reticulofenestrids) to test the influence that cell size variability played in determining epsilon [p37:2] trends and pCO2 estimates during the middle Eocene to early Miocene. At the investigated deep-sea sites, the reticulofenestrids experienced high diversity and largest mean cell sizes during the late Eocene, followed by a long-term decrease in maximum cell size since the earliest Oligocene. Decreasing haptophyte cell sizes do not account for the long-term increase in the stable carbon isotopic composition of alkenones and associated decrease in epsilon [p37:2] values during the Paleogene, supporting the conclusion that the secular pattern of epsilon [p37:2] values is primarily controlled by decreasing CO2 concentration since the earliest Oligocene. Further, given the physiology of modern alkenone producers, and considering the timings of coccolithophorid cell size change, extinctions, and changes in reconstructed pCO2 and temperature, we speculate that the selection of smaller reticulofenestrid cells during the Oligocene primarily reflects an adaptive response to increased [CO2(aq)] limitation.

Digital surface model, hillshade and orthophoto of the world's largest fossil oyster reef, links to GeoTIFFs

The world's largest fossil oyster reef, formed by the giant oyster Crassostrea gryphoides and located in Stetten (north of Vienna, Austria) is studied by Harzhauser et al., 2015, 2016; Djuricic et al., 2016. Digital documentation of the unique geological site is provided by terrestrial laser scanning (TLS) at the millimeter scale. Obtaining meaningful results is not merely a matter of data acquisition with a suitable device; it requires proper planning, data management, and postprocessing. Terrestrial laser scanning technology has a high potential for providing precise 3D mapping that serves as the basis for automatic object detection in different scenarios; however, it faces challenges in the presence of large amounts of data and the irregular geometry of an oyster reef. We provide a detailed description of the techniques and strategy used for data collection and processing in Djuricic et al., 2016. The use of laser scanning provided the ability to measure surface points of 46,840 (estimated) shells. They are up to 60-cm-long oyster specimens, and their surfaces are modeled with a high accuracy of 1 mm. In addition to laser scanning measurements, more than 300 photographs were captured, and an orthophoto mosaic was generated with a ground sampling distance (GSD) of 0.5 mm. This high-resolution 3D information and the photographic texture serve as the basis for ongoing and future geological and paleontological analyses. Moreover, they provide unprecedented documentation for conservation issues at a unique natural heritage site.