Phylogenetic, ecological and intraindividual variability patterns in grass phytolith shape

Grass silica short cell (GSSC) phytoliths appear to be the most reliable source of fossil evidence for tracking the evolutionary history and paleoecology of grasses. In recent years, modern techniques have been used to quantitatively assess phytolith shape variation. This progress has widened opportunities with respect to the classification of grass fossil phytoliths. However, phylogenetic, ecological and intraindividual variability patterns in phytolith shape remain largely unexplored. The full range of intraindividual phytolith shape variation (3650 2D outlines) from 73 extant grass species, 48 genera, 18 tribes, and 8 subfamilies (with special attention paid to Pooideae) was analysed using the geometric morphometric analysis based on the semilandmarks spanning phytolith outlines. Although we showed that 2D phytolith shape is mainly driven by deep-time diversification of grass subfamilies, a closer look uncovered distinct phytolith shape variation in early-diverging lineages of Pooideae. The phylogenetic pattern in phytolith shape was successfully revealed by applying geometric morphometrics to 2D phytolith shape outlines. This finding strengthens the potential of phytoliths to track the evolutionary history and paleoecology of grasses. Moreover, geometric morphometrics of 2D phytolith shape proved to be an excellent tool for analysis requiring large sums of phytolith outlines, making it useful for quantitative palaeoecological reconstruction.

MetaDamage Tool: Examining post-mortem damage in sedaDNA on a metagenomic scale

<p>Authentication of ancient sedimentary DNA (sedaDNA) remains central to the interpretation of the proxy for wider understanding of palaeoecological archives. Distinguishing between in-situ, endogenous sedaDNA from that of contamination or modern material also allows for a wider understanding of taphonomy in the deposition and post-depositional process in the formation of the sedaDNA archive. At current, tools for authentication are reliant on single-taxon input and require a significant number of input sequences to identify an established cytosine deamination rate consistent with ancient DNA. We present the MetaDamage tool: a tool that examines cytosine deamination on a metagenomic scale. In this paper we outline the process of and testing of the MetaDamage tool using both authentic sedaDNA sequences and simulated data in order to demonstrate the resolution in which MetaDamage can observe deamination levels consistent with the presence of ancient DNA. The MetaDamage tool offers a method for initial assessment of the presence of ancient sedaDNA and provides a method for a wider understanding of key questions of preservation for palaeoecological reconstruction.</p>

The best of all possible coexistence

The writings of Gottfried Wilhelm Leibniz (1646–1716) provide a window on early evolutionary thinking of a kind interestingly different from the roots of modern evolutionary theory as it emerged in the years following the French Revolution. Here we relate aspects of Leibniz’s thinking to methods of modern palaeoecology and show that, despite a different terminology and a different hierarchic focus, Leibniz emerges as a strikingly modern theoretician, who viewed the living world as dynamic and capable of adaptive change. The coexistence approach of palaeoecological reconstruction, developed by Volker Mosbrugger and collaborators, with its core assumption of harmoniously co-adapted communities with strong historical legacy, represents, in a positive sense, a more Leibnizian view than functionally based and theoretically history-free approaches, such as ecometrics. Recalling Leibniz’s thinking helps to highlight how palaeoecological reconstruction is about much more than reliably establishing the ecological and climatic situation of a given fossil locality. While reliable reconstructions of past conditions are certainly of great value in research, it is arguably the need to think deeply about how the living world really works that keeps palaeoecological reconstruction such a long-running and central aspect of evolutionary science. And while we struggle to understand the coexistence and dynamic interaction of endless levels of living agents of the living world, simultaneously large and small, global and local, the coexistence approach of palaeoecological reconstruction remains both an outstandingly operational method and part of a philosophical tradition reaching back to the very earliest evolutionary thinking.

Palaeoenvironmental significance of a late Miocene benthic foraminifera fauna from Apostoli Formation, Central West Crete, Greece

The palaeoenvironmental and palaeoecological reconstruction of the Apostoli Basin (Crete, Rethymnon Region) during early Late Miocene by means of benthic foraminifers is given. Biologically important factors, such as oxygen and nutrient content of sea-water, played a great role in the evolution of the palaeoecosystem. A gradual deepening took place during the deposition of the Apostoli Formation. The sediments of the lower part of the formation document a shallow-marine environment with vegetation in the neighborhood. In the middle part of the formation sediments are characterized by intermediate oxygenated conditions, whereas the upper part of it is characterized by the establishment of a restricted envrironment, where organic matter accumulates and infaunal opportunistic species capable of surviving in stressed conditions dominate, being favoured by abundant nutrients.

Moa diet fits the bill: virtual reconstruction incorporating mummified remains and prediction of biomechanical performance in avian giants

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowledge about niche partitioning, feeding mode and preference among moa species is limited, hampering palaeoecological reconstruction and evaluation of the impacts of their extinction on remnant native biota, or the viability of exotic species as proposed ecological ‘surrogates'. Here we apply three-dimensional finite-element analysis to compare the biomechanical performance of skulls from five of the six moa genera, and two extant ratites, to predict the range of moa feeding behaviours relative to each other and to living relatives. Mechanical performance during biting was compared using simulations of the birds clipping twigs based on muscle reconstruction of mummified moa remains. Other simulated food acquisition strategies included lateral shaking, pullback and dorsoventral movement of the skull. We found evidence for limited overlap in biomechanical performance between the extant emu ( Dromaius novaehollandiae ) and extinct upland moa ( Megalapteryx didinus ) based on similarities in mandibular stress distribution in two loading cases, but overall our findings suggest that moa species exploited their habitats in different ways, relative to both each other and extant ratites. The broad range of feeding strategies used by moa, as inferred from interspecific differences in biomechanical performance of the skull, provides insight into mechanisms that facilitated high diversities of these avian herbivores in prehistoric New Zealand.