What makes a long tail short? Testing Allen's rule in the toque macaques of Sri Lanka

Allen's rule (1877) predicts ecogeographical anatomical variation in appendage proportions as a function of body temperature regulation. This phenomenon has been tested in a variety of animal species. In macaques, relative tail length (RTL) is one of the most frequently measured appendages to test Allen's rule. These studies have relied on museum specimens or the invasive and time-consuming capturing of free-ranging individuals. To augment sample size and lessen these logistical limitations, we designed and validated a novel noninvasive technique using digitalized photographs processed using LibreCAD, an open-source 2D-computer-aided design (CAD) application. This was used to generate pixelated measurements to calculate an RTL equivalent, the Tail to Trunk Index (TTI) = (tail [tail base to anterior tip] pixel count/trunk [neck to tail base] pixel count). The TTI of 259 adult free-ranging toque macaques (Macaca sinica) from 36 locations between 7 and 2,087 m above sea level (m.a.s.l.) was used in the analysis. Samples were collected from all three putative subspecies (M. s. sinica, aurifrons, and opisthomelas), at locations representing all altitudinal climatic zones where they are naturally distributed. These data were used to test whether toque macaque tail length variation across elevation follows Allen's rule, predicting that RTL decreases with increasing elevation and lower temperature. Our results strongly supported this prediction. There was also a statistically significant, negative correlation between elevation and annual average temperature. The best predictor for the TTI index was elevation. Significant subspecies differences in RTL are linked in part to their ecological and altitudinal niche separation, but overall the variation is seen as the species' adaptation to climate. The method developed for the quick morphometric assessment of relative body proportions, applicable for use on unhabituated free-ranging animals, widens the range of materials available for research studying morphological characteristics and their evolution in primates.     

Recognition of gluconeogenic enzymes; Icl1, Fbp1, and Mdh2 by Gid4 ligase: A molecular docking study

The pro/N‐degron pathway is an evolved protein degradation pathway through the ubiquitin‐proteasome system. It is a vital pathway to attain protein homeostasis inside the liver cells with varying glucose levels. N‐terminal proline exists in more than 300 proteins in Saccharomyces cerevisiae, but only three of them are the gluconeogenic enzymes; isocitrate lyase (Icl1), fructose‐1,6‐bisphosphatase (Fbp1), and malate dehydrogenase (Mdh2). The present in silico study aims to structurally illustrate the binding of Icl1 enzyme to Gid4 ligase concerning its peers; Fbp1 and Mdh2. Based on the molecular docking scores and interactions, one can attribute the binding stability of Gid4 with degrons, to peptides of length six up to eight from the N‐terminal. Moreover, the percent change in the docking score provides a rationale for the unique Gid4‐Icl1^1‐4 interaction. The present study provides insights on the binding attitude of Gid4 ligase to degrons of different lengths, so one will consider in designing peptidomimetics to target Gid4 ligase.     

Morphological divergence in giant fossil dormice

Insular gigantism—evolutionary increases in body size from small-bodied mainland ancestors—is a conceptually significant, but poorly studied, evolutionary phenomenon. Gigantism is widespread on Mediterranean islands, particularly among fossil and extant dormice. These include an extant giant population of Eliomys quercinus on Formentera, the giant Balearic genus †Hypnomys and the exceptionally large †Leithia melitensis of Pleistocene Sicily. We quantified patterns of cranial and mandibular shape and their relationships to head size (allometry) among mainland and insular dormouse populations, asking to what extent the morphology of island giants is explained by allometry. We find that gigantism in dormice is not simply an extrapolation of the allometric trajectory of their mainland relatives. Instead, a large portion of their distinctive cranial and mandibular morphology resulted from the population- or species-specific evolutionary shape changes. Our findings suggest that body size increases in insular giant dormice were accompanied by the evolutionary divergence of feeding adaptations. This complements other evidence of ecological divergence in these taxa, which span predominantly faunivorous to herbivorous diets. Our findings suggest that insular gigantism involves context-dependent phenotypic modifications, underscoring the highly distinctive nature of island faunas.     

Effects of thermal and oxygen conditions during development on cell size in the common rough woodlice Porcellio scaber

During development, cells may adjust their size to balance between the tissue metabolic demand and the oxygen and resource supply: Small cells may effectively absorb oxygen and nutrients, but the relatively large area of the plasma membrane requires costly maintenance. Consequently, warm and hypoxic environments should favor ectotherms with small cells to meet increased metabolic demand by oxygen supply. To test these predictions, we compared cell size (hindgut epithelium, hepatopancreas B cells, ommatidia) in common rough woodlice (Porcellio scaber) that were developed under four developmental conditions designated by two temperatures (15 or 22°C) and two air O₂ concentrations (10% or 22%). To test whether small‐cell woodlice cope better under increased metabolic demand, the CO₂ production of each woodlouse was measured under cold, normoxic conditions and under warm, hypoxic conditions, and the magnitude of metabolic increase (MMI) was calculated. Cell sizes were highly intercorrelated, indicative of organism‐wide mechanisms of cell cycle control. Cell size differences among woodlice were largely linked with body size changes (larger cells in larger woodlice) and to a lesser degree with oxygen conditions (development of smaller cells under hypoxia), but not with temperature. Developmental conditions did not affect MMI, and contrary to predictions, large woodlice with large cells showed higher MMI than small woodlice with small cells. We also observed complex patterns of sexual difference in the size of hepatopancreatic cells and the size and number of ommatidia, which are indicative of sex differences in reproductive biology. We conclude that existing theories about the adaptiveness of cell size do not satisfactorily explain the patterns in cell size and metabolic performance observed here in P. scaber. Thus, future studies addressing physiological effects of cell size variance should simultaneously consider different organismal elements that can be involved in sustaining the metabolic demands of tissue, such as the characteristics of gas‐exchange organs and O₂‐binding proteins.     

Do microbes have macroecology? Large‐scale patterns in the diversity and distribution of marine benthic ciliates

Aim The biogeography and global distribution of protists has long been disputed, with two primary, opposing views. To test these two sets of views in greater detail, we have compiled the available data for marine benthic ciliates and assessed the general patterns of their diversity and distribution compared with Metazoa. Location World‐wide. Methods A comprehensive database (1342 species, over 350 sources) was used to analyse the diversity, distribution, species occurrences and range size distribution of free‐living ciliates that inhabit marine sediments in 17 geographical regions. Results Twenty‐five per cent of the species have been found in a single region only, whereas 18% are widespread (they occur in more than half the regions covering both hemispheres). Only 5–7% of regional faunas are endemic, which is much lower than for macroorganisms. Regional diversity depends neither on total area nor on coastline length and does not show any obvious latitudinal trends, but correlates highly with the investigation effort expended in a region and (negatively) with the average salinity. A comparison of species composition reveals distinctions between the Arctic Area (the White, Barents and Kara seas), Laurasian Area (north Atlantic, north Pacific and European seas), Gondwanian Area (Southern Ocean) and the Antarctic. No clear geographical correlations are found for faunistic composition at the genus or family levels. There is the tendency to narrow the latitudinal ranges for species found at high latitudes (reversal of Rapoport's rule). Main conclusions Undersampling and data insufficiency are the key factors affecting the observed diversity and distribution of microorganisms. Nevertheless, marine benthic ciliates demonstrate certain patterns that generally agree with the ‘moderate endemicity’ model ( Foissner, 2004, 2008 ), but consistently contradict the regularities commonly observed for multicellular taxa. Thus, ciliates do have a biogeography, but their macroecological patterns may be different in some respects from that of macroorganisms.     

Environment predicts repeated body size shifts in a recent radiation of Australian mammals*

Closely related species that occur across steep environmental gradients often display clear body size differences, and examining this pattern is crucial to understanding how environmental variation shapes diversity. Australian endemic rodents in the Pseudomys Division (Muridae: Murinae) have repeatedly colonized the arid, monsoon, and mesic biomes over the last 5 million years. Using occurrence records, body mass data, and Bayesian phylogenetic models, we test whether body mass of 31 species in the Pseudomys Division can be predicted by their biome association. We also model the effect of eight environmental variables on body mass. Despite high phylogenetic signal in body mass evolution across the phylogeny, we find that mass predictably increases in the mesic biome and decreases in arid and monsoon biomes. As per Bergmann's rule, temperature is strongly correlated with body mass, as well as several other variables. Our results highlight two important findings. First, body size in Australian rodents has tracked with climate through the Pleistocene, likely due to several environmental variables rather than a single factor. Second, support for both Brownian motion and predictable change at different taxonomic levels in the Pseudomys Division phylogeny demonstrates how the level at which we test hypotheses can alter interpretation of evolutionary processes.     

Inflorescences: concepts,function, development and evolution

Background

Inflorescences are complex structures with many functions. At anthesis they present the flowers in ways that allow for the transfer of pollen and optimization of the plant''s reproductive success. During flower and fruit development they provide nutrients to the developing flowers and fruits. At fruit maturity they support the fruits prior to dispersal, and facilitate effective fruit and seed dispersal. From a structural point of view, inflorescences have played important roles in systematic and phylogenetic studies. As functional units they facilitate reproduction, and are largely shaped by natural selection.

Scope

The papers in this Special Issue bridge the gap between structural and functional approaches to inflorescence evolution. They include a literature review of inflorescence function, an experimental study of inflorescences as essential contributors to the display of flowers, and two papers that present new methods and concepts for understanding inflorescence diversity and for dealing with terminological problems. The transient model of inflorescence development is evaluated in an ontogenetic study, and partially supported. Four papers present morphological and ontogenetic studies of inflorescence development in monophyletic groups, and two of these evaluate the usefulness of Hofmeister''s Rule and inhibitory fields to predict inflorescence structure. In the final two papers, Bayesian and Monte-Carlo methods are used to elucidate inflorescence evolution in the Panicoid grasses, and a candidate gene approach is used in an attempt to understand the evolutionary genetics of inflorescence evolution in the genus Cornus (Cornaceae). Taken as a whole, the papers in this issue provide a glimpse of contemporary approaches to the study of the structure, development, and evolution of inflorescences, and suggest fruitful new directions for research.