Functional and ecological correlates of ecologically-based dimorphisms in squamate reptiles

Sexual dimorphism in phenotypic traits associated with the useof resources is a widespread phenomenon throughout the animalkingdom. While ecological dimorphisms are often initially generatedby sexual selection operating on an animal's size, natural selectionis believed to maintain, or even amplify, these dimorphismsin certain ecological settings. The trophic apparatus of snakeshas proven to be a model system for testing the adaptive natureof ecological dimorphisms because head size is rarely undersexual selection and it limits the maximum ingestible size ofprey in these gape-limited predators. Significantly less attentionhas been paid to the evolution of ecological dimorphisms inlizards, however, which may be due to the fact that lizards’feeding apparatus can be under both sexual and natural selectionsimultaneously, making it difficult to formulate clear-cut hypothesesto distinguish between the influences of natural and sexualselection. In order to tease apart the respective influencesof natural selection and sexual selection on the feeding apparatusof squamates, we take an integrative approach to formulate twohypotheses for snakes and lizards, respectively: (1) For gape-limitedsnakes, we predict that natural selection will act to generatedifferences in maximum gape, which will translate into differencesin maximum ingestible prey size between the sexes. (2) For lizardswhich mechanically reduce their prey, we predict that the degreeof dimorphism in head size should be positively correlated tothe degree of dimorphism in bite force which, in turn, shouldbe correlated to dimorphism in aspects of size or hardness ofprey. Finally, we predict that functional differences in thefeeding apparatus of these animals will also be linked withdifferences in sex-based feeding behavior and with selectionof prey.     

Open syntaxin docks synaptic vesicles

Synaptic vesicles dock to the plasma membrane at synapses to facilitate rapid exocytosis. Docking was originally proposed to require the soluble N-ethylmaleimide–sensitive fusion attachment protein receptor (SNARE) proteins; however, perturbation studies suggested that docking was independent of the SNARE proteins. We now find that the SNARE protein syntaxin is required for docking of all vesicles at synapses in the nematode Caenorhabditis elegans. The active zone protein UNC-13, which interacts with syntaxin, is also required for docking in the active zone. The docking defects in unc-13 mutants can be fully rescued by overexpressing a constitutively open form of syntaxin, but not by wild-type syntaxin. These experiments support a model for docking in which UNC-13 converts syntaxin from the closed to the open state, and open syntaxin acts directly in docking vesicles to the plasma membrane. These data provide a molecular basis for synaptic vesicle docking.     

Using unmanned aerial vehicle‐based multispectral,RGB and thermal imagery for phenotyping of forest genetic trials: A case study in Pinus halepensis

The assessment of genetic differentiation in functional traits is fundamental towards understanding the adaptive characteristics of forest species. While traditional phenotyping techniques are costly and time‐consuming, remote sensing data derived from cameras mounted on unmanned aerial vehicles (UAVs) provide potentially valid high‐throughput information for assessing morphophysiological differences among tree populations. In this work, we test for genetic variation in vegetation indices (VIs) and canopy temperature among populations of Pinus halepensis as proxies for canopy architecture, leaf area, photosynthetic pigments, photosynthetic efficiency and water use. The interpopulation associations between vegetation properties and above‐ground growth (stem volume) were also assessed. Three flights (July 2016, November 2016 and May 2017) were performed in a genetic trial consisting of 56 populations covering a large part of the species range. Multispectral (visible and near infrared wavelengths), RGB (red, green, blue) and thermal images were used to estimate canopy temperature and vegetation cover (VC) and derive several VIs. Differences among populations emerged consistently across flights for VC and VIs related to leaf area, indicating genetic divergence in crown architecture. Population differences in indices related to photosynthetic pigments emerged only in May 2017 and were probably related to a contrasting phenology of needle development. Conversely, the low population differentiation for the same indices in July 2016 and November 2016 suggested weak interpopulation variation in the photosynthetic machinery of mature needles of P. halepensis. Population differences in canopy temperature found in July 2016 were indicative of variation in stomatal regulation under drought stress. Stem volume correlated with indices related to leaf area (positively) and with canopy temperature (negatively), indicating a strong influence of canopy properties and stomatal conductance on above‐ground growth at the population level. Specifically, a combination of VIs and canopy temperature accounted for about 60% of population variability in stem volume of adult trees. This is the first study to propose UAV remote sensing as an effective tool for screening genetic variation in morphophysiological traits of adult forest trees.     

Split-enzyme fragment as a single affinity tag that enables protein expression,purification, and functional assays

Expressing, isolating, and characterizing recombinant proteins is crucial to many disciplines within the biological sciences. Different molecular tagging technologies have been developed to enable each individual step of protein production, from expression through purification and characterization. Monitoring the entire production process requires multiple tags or molecular interactions, because no individual tag has provided the comprehensive breadth of utility. An ideal molecular tag is small and does not interrupt expression, solubility, folding or function of the protein being purified and can be used throughout the production process. We adapted and integrated a split-luciferase system (NanoBiT®, Promega ®) to perform the range of techniques essential to protein production. We developed a simple method to monitor protein expression in real time to optimize expression conditions. We constructed a novel affinity chromatography system using the split-luciferase system to enable purification. We adapted western blot analysis, enzyme-linked immunosorbent assay, and cell-based bioassay to characterize the expressed proteins. Our results demonstrate that a single-tag can fulfill all aspects needed throughout protein production.     

Do phytogeographic patterns reveal biomes or biotic regions?

We present the largest comparative biogeographical analysis that has complete coverage of Australia's geography (20 phytogeographical subregions), using the most complete published molecular phylogenies to date of large Australian plant clades (Acacia, Banksia and the eucalypts). Two distinct sets of areas within the Australian flora were recovered, using distributional data from the Australasian Virtual Herbarium (AVH) and the Atlas of Living Australia (ALA): younger Temperate, Eremaean and Monsoonal biomes, and older southwest + west, southeast and northern historical biogeographical regions. The analyses showed that by partitioning the data into two sets, using either a Majority or a Frequency method to select taxon distributions, two equally valid results were found. The dataset that used a Frequency method discovered general area cladograms that resolved patterns of the Australian biomes, whereas if widespread taxa (Majority method, with >50% of occurrences outside a single subregion) were removed the analysis then recovered historical biogeographical regions. The study highlights the need for caution when processing taxon distributions prior to analysis as, in the case of the history of Australian phytogeography, the validity of both biomes and historical areas have been called into question.     

Ancient DNA analysis of Fremont Amerindians of the Great Salt Lake Wetlands

Skeletal remains of 47 individuals from the Great Salt Lake Wetlands, affiliated principally with Bear River (A.D. 400—1000) and Levee Phase (A.D. 1000—1350) Fremont cultural elements, were assessed for four mitochondrial DNA (mtDNA) markers that, in particular association, define four haplogroups (A, B, C, and D) widely shared among contemporary Amerindians groups. The most striking result is the absence of haplogroup A in this Fremont series, despite its predominance in contemporary Amerindian groups. Additionally, haplogroup B, defined by the presence of a 9bp deletion in region V, is present at the moderately high frequency of 60%. Haplogroups C and D are present at low frequencies. An additional haplotype, "N, observed in some modern populations and two other prehistoric samples, is also present in this Fremont skeletal collection. © 1996 Wiley-Liss, Inc.     

Climate alters the movement ecology of a non‐migratory bird

Global climate change is causing increased climate extremes threatening biodiversity and altering ecosystems. Climate is comprised of many variables including air temperature, barometric pressure, solar radiation, wind, relative humidity, and precipitation that interact with each other. As movement connects various aspects of an animal''s life, understanding how climate influences movement at a fine‐temporal scale will be critical to the long‐term conservation of species impacted by climate change. The sedentary nature of non‐migratory species could increase some species risk of extirpation caused by climate change. We used Northern Bobwhite (Colinus virginianus; hereafter bobwhite) as a model to better understand the relationship between climate and the movement ecology of a non‐migratory species at a fine‐temporal scale. We collected movement data on bobwhite from across western Oklahoma during 2019–2020 and paired these data with meteorological data. We analyzed movement in three different ways (probability of movement, hourly distance moved, and sinuosity) using two calculated movement metrics: hourly movement (displacement between two consecutive fixes an hour apart) and sinuosity (a form of tortuosity that determines the amount of curvature of a random search path). We used generalized linear‐mixed models to analyze probability of movement and hourly distance moved, and used linear‐mixed models to analyze sinuosity. The interaction between air temperature and solar radiation affected probability of movement and hourly distance moved. Bobwhite movement increased as air temperature increased beyond 10°C during low solar radiation. During medium and high solar radiation, bobwhite moved farther as air temperature increased until 25–30°C when hourly distance moved plateaued. Bobwhite sinuosity increased as solar radiation increased. Our results show that specific climate variables alter the fine‐scale movement of a non‐migratory species. Understanding the link between climate and movement is important to determining how climate change may impact a species’ space use and fitness now and in the future.     

Evidence for the emergence of β-trefoils by ‘Peptide Budding’ from an IgG-like β-sandwich

As sequence and structure comparison algorithms gain sensitivity, the intrinsic interconnectedness of the protein universe has become increasingly apparent. Despite this general trend, β-trefoils have emerged as an uncommon counterexample: They are an isolated protein lineage for which few, if any, sequence or structure associations to other lineages have been identified. If β-trefoils are, in fact, remote islands in sequence-structure space, it implies that the oligomerizing peptide that founded the β-trefoil lineage itself arose de novo. To better understand β-trefoil evolution, and to probe the limits of fragment sharing across the protein universe, we identified both ‘β-trefoil bridging themes’ (evolutionarily-related sequence segments) and ‘β-trefoil-like motifs’ (structure motifs with a hallmark feature of the β-trefoil architecture) in multiple, ostensibly unrelated, protein lineages. The success of the present approach stems, in part, from considering β-trefoil sequence segments or structure motifs rather than the β-trefoil architecture as a whole, as has been done previously. The newly uncovered inter-lineage connections presented here suggest a novel hypothesis about the origins of the β-trefoil fold itself–namely, that it is a derived fold formed by ‘budding’ from an Immunoglobulin-like β-sandwich protein. These results demonstrate how the evolution of a folded domain from a peptide need not be a signature of antiquity and underpin an emerging truth: few protein lineages escape nature’s sewing table.