The Effects of Residency and Body Size on Contest Initiation and Outcome in the Territorial Dragon, Ctenophorus decresii

Empirical studies of the determinants of contests have been attempting to unravel the complexity of animal contest behaviour for decades. This complexity requires that experiments incorporate multiple determinants into studies to tease apart their relative effects. In this study we examined the complex contest behaviour of the tawny dragon (Ctenophorus decresii), a territorial agamid lizard, with the specific aim of defining the factors that determine contest outcome. We manipulated the relative size and residency status of lizards in contests to weight their importance in determining contest outcome. We found that size, residency and initiating a fight were all important in determining outcomes of fights. We also tested whether residency or size was important in predicting the status of lizard that initiated a fight. We found that residency was the most important factor in predicting fight initiation. We discuss the effects of size and residency status in context of previous studies on contests in tawny dragons and other animals. Our study provides manipulative behavioural data in support of the overriding effects of residency on initiation fights and winning them.This study was funded by the Australian Research Council (www.arc.gov.au), the School of Botany and Zoology, and ANU (www.anu.edu.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Genetic and environmental drivers of colour and pattern in the Australian jacky dragon (Amphibolurus muricatus)

The underlying drivers of variation in the colouration (colour and pattern) of animals can be genetic, non-genetic, or more likely, a combination of both. Understanding the role of heritable genetic elements, as well as non-genetic factors such as age, habitat or temperature, in shaping colouration can provide insight into the evolution and function of these traits, as well as the speed of response to changing environments. This project examined the genetic and non-genetic drivers of continuous variation in colouration in a lizard, the jacky dragon (Amphibolurus muricatus). We leveraged a large captive experiment that manipulated parental and offspring thermal environment to simultaneously estimate the genetic and non-genetic drivers of variation in colouration. We found that the overall brightness, the elongation of the longitudinal stripes on the dorsum and the contrast between light and dark patches of the pattern were all heritable. Colouration varied according to the age of the hatchling; however, the thermal environment of neither the parents nor offspring contributed significantly to colouration. It appears that developmental plasticity and maternal effects associated with temperature are not important drivers of variation in our measures of colouration

Predicting species and community responses to global change using structured expert judgement : an Australian mountain ecosystems case study

Conservation managers are under increasing pressure to make decisions about the allocation of finite resources to protect biodiversity under a changing climate. However, the impacts of climate and global change drivers on species are outpacing our capacity to collect the empirical data necessary to inform these decisions. This is particularly the case in the Australian Alps which has already undergone recent changes in climate and experienced more frequent large-scale bushfires. In lieu of empirical data, we used a structured expert elicitation method (the IDEA protocol) to estimate the abundance and distribution of nine vegetation groups and 89 Australian alpine and subalpine species by the year 2050. Experts predicted that most alpine vegetation communities would decline in extent by 2050; only woodlands and heathlands are predicted to increase in extent. Predicted species-level responses for alpine plants and animals were highly variable and uncertain. In general, alpine plants spanned the range of possible responses, with some expected to increase, decrease or not change in cover. By contrast, almost all animal species are predicted to decline or not change in abundance or elevation range; more species with water-centric life-cycles are expected to decline in abundance than other species. While long-term ecological data will always be the gold-standard in informing the future of biodiversity, the method and outcomes outlined here provide a pragmatic and coherent basis upon which to start informing conservation policy and management in the face of rapid change and paucity of data

On the perception, production and function of blue colouration in animals

Bright colouration in animals has long attracted the attention of physicists, chemists and biologists. As such, studies on the functions of colours are interdisciplinary, focusing on the mechanisms of colour production and maintenance, the physical and chemical properties of the colour-producing elements, and visual systems and behaviour of potential receivers. Blue colouration has received a large share of research attention and is fascinating for several reasons: blue has been attributed to a very broad range of functions, blue is achieved by a great variety of mechanisms (although their production and maintenance costs are currently unclear), and the blue part of the spectrum (450-490nm) can be perceived by most taxa. This review explores the breadth of studies that propose a function for blue colouration. In so doing, it discusses the diversity of ways in which blue colours are produced both as pigments and structural colours, and that blue visual pigments are common across a broad range of taxa. This analysis of the current literature emphasizes the importance of multidisciplinary hypothesis testing when attempting to elucidate the function of colours, the need for manipulative over correlative evidence for the function of colours, and, as colour research becomes evermore interdisciplinary, the need for well-defined consistent terminology.14 page(s

Microsatellite Markers for the Chameleon Grasshopper (Kosciuscola tristis) (Orthoptera: Acrididae), an Australian Alpine Specialist

A set of polymorphic loci was characterised using an enrichment library for the Australian alpine specialist, the chameleon grasshopper (Kosciuscola tristis), an atypical grasshopper known for its remarkable temperature-controlled colour change. The number of alleles per locus ranged from three to 20 and observed heterozygosity from 0.16 to 0.76. These are the first microsatellite markers for a non-endangered Australian alpine animal and will inform questions of gene flow across the sky islands of this unique and threatened region

The mothematics of female pheromone signaling: strategies for aging virgins

Although females rarely experience strong mate limitation, delays or lifelong problems of mate acquisition are detrimental to female fitness. In systems where males search for females via pheromone plumes, it is often difficult to assess whether female signaling is costly. Direct costs include the energetics of pheromone production and attention from unwanted eavesdroppers, such as parasites, parasitoids, and predators. Suboptimal outcomes are also possible from too many or too few mating events or near-simultaneous arrival of males who make unwanted mating attempts (even if successfully thwarted). We show that, in theory, even small costs can lead to a scenario where young females signal less intensely (lower pheromone concentration and/or shorter time spent signaling) and increase signaling effort only as they age and gather evidence (while still virgin) on whether sperm limitation threatens their reproductive success. Our synthesis of the empirical data available on Lepidoptera supports this prediction for one frequently reported component of signaling-time spent calling (often reported as the time of onset of calling at night)-but not for another, pheromone titer. This difference is explicable under the plausible but currently untested assumption that signaling earlier than other females each night is a more reliable way of increasing the probability of acquiring at least one mate than producing a more concentrated pheromone plume

Ecological responses to variation in seasonal snow cover

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment. Understanding how individuals, populations, and communities respond to different snow conditions is thus essential for predicting and managing future ecosystem change. We synthesized 365 studies that examined ecological responses to variation in winter snow conditions. This research encompasses a broad range of methods (experimental manipulations, measurement of natural snow gradients, and long-term monitoring), locations (35 countries), study organisms (plants, mammals, arthropods, birds, fish, lichen, and fungi), and response measures. Earlier snowmelt was consistently associated with advanced spring phenology in plants, mammals, and arthropods. Reduced snow depth often increased mortality or physical injury in plants, although there were few clear effects on animals. Neither snow depth nor snowmelt timing had clear or consistent directional effects on body size of animals or biomass of plants. However, because 96% of studies were from the northern hemisphere, the generality of these trends across ecosystems and localities is also unclear. We identified substantial research gaps for several taxonomic groups and response types; research on wintertime responses was notably scarce. Future research should prioritize examination of the mechanisms underlying responses to changing snow conditions and the consequences of those responses for seasonally snow-covered ecosystems.R.S. was supported by an American Australia Association fellowship while completing this wor