A TEX86 surface sediment database and extended Bayesian calibration

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Data 2 (2015): 150029, doi:10.1038/sdata.2015.29.Quantitative estimates of past temperature changes are a cornerstone of paleoclimatology. For a number of marine sediment-based proxies, the accuracy and precision of past temperature reconstructions depends on a spatial calibration of modern surface sediment measurements to overlying water temperatures. Here, we present a database of 1095 surface sediment measurements of TEX86, a temperature proxy based on the relative cyclization of marine archaeal glycerol dialkyl glycerol tetraether (GDGT) lipids. The dataset is archived in a machine-readable format with geospatial information, fractional abundances of lipids (if available), and metadata. We use this new database to update surface and subsurface temperature calibration models for TEX86 and demonstrate the applicability of the TEX86 proxy to past temperature prediction. The TEX86 database confirms that surface sediment GDGT distribution has a strong relationship to temperature, which accounts for over 70% of the variance in the data. Future efforts, made possible by the data presented here, will seek to identify variables with secondary relationships to GDGT distributions, such as archaeal community composition

Smart Moves: Effects of Relative Brain Size on Establishment Success of Invasive Amphibians and Reptiles

Brain size relative to body size varies considerably among animals, but the ecological consequences of that variation remain poorly understood. Plausibly, larger brains confer increased behavioural flexibility, and an ability to respond to novel challenges. In keeping with that hypothesis, successful invasive species of birds and mammals that flourish after translocation to a new area tend to have larger brains than do unsuccessful invaders. We found the same pattern in ectothermic terrestrial vertebrates. Brain size relative to body size was larger in species of amphibians and reptiles reported to be successful invaders, compared to species that failed to thrive after translocation to new sites. This pattern was found in six of seven global biogeographic realms; the exception (where relatively larger brains did not facilitate invasion success) was Australasia. Establishment success was also higher in amphibian and reptile families with larger relative brain sizes. Future work could usefully explore whether invasion success is differentially associated with enlargement of specific parts of the brain (as predicted by the functional role of the forebrain in promoting behavioural flexibility), or with a general size increase (suggesting that invasion success is facilitated by enhanced perceptual and motor skills, as well as cognitive ability)

Brain Deletion of Insulin Receptor Substrate 2 Disrupts Hippocampal Synaptic Plasticity and Metaplasticity

Diabetes mellitus is associated with cognitive deficits and an increased risk of dementia, particularly in the elderly. These deficits and the corresponding neurophysiological structural and functional alterations are linked to both metabolic and vascular changes, related to chronic hyperglycaemia, but probably also defects in insulin action in the brain. To elucidate the specific role of brain insulin signalling in neuronal functions that are relevant for cognitive processes we have investigated the behaviour of neurons and synaptic plasticity in the hippocampus of mice lacking the insulin receptor substrate protein 2 (IRS-2)

Comment: Hierarchical Statistical Modeling for Paleoclimate Reconstruction

The article by Bo Li, Douglas W. Nychka, and Caspar M. Ammann (hereafter, LNA) has several goals. It considers the important problem of reconstruction of past (over a period of more than 1000 Years Before Present) climate from multiproxy data, and it directly recognizes the various uncertainties in this undertaking. These uncertainties are expressed through (conditional) probability distributions in a framework known to readers of this journal as hierarchical statistical modeling. LNA use a physical–statistical model that also includes climate forcings, and their statistical inference is Bayesian. Rather than using actual multiproxy data, LNA simulate their data. Then they design a computer-simulation experiment to assess the value of including the various (simulated) proxies and the forcings. The design of the experiment, its analysis, and the conclusions obtained from it, are intended to guide climate scientists towards more precise inferences when carrying out actual paleoclimate reconstructions. Our discussion of LNA in the sections that follow considers both the scientific and statistical goals summarized above

TEX86 Database Metadata File

<p>This metadata file describes the variables in the TEX86 database and provides the associated references.</p

TEX86 Surface Sediment Database

<p>This file contains a database of modern sediment observations of the TEX86 temperature proxy, an index that describes the relative cyclization of marine archaeal glycerol dialkyl glycerol tetraethers. Please refer to the separate metadata file for a description of the variables. Note that missing values appear as -999. This is database version 1.0.</p