Species Of Similar Size Research Articles

Revisiting Molossus (Mammalia: Chiroptera: Molossidae) diversity: Exploring southern limits and revealing a novel species in Argentina

Abstract Understanding species diversity and delineating their boundaries are crucial for effective management and conservation efforts. In the case of bats, species identification holds particular importance from an epidemiological standpoint. The genus Molossus (Chiroptera: Molossidae) encompasses 15 species distributed across the Neotropics, ranging from the southeastern United States to Argentina. This genus exhibits two contrasting patterns of variation: some species are cryptic, while others are morphologically distinct yet genetically similar. This study explores the diversity of Molossus in Argentina through a molecular phylogenetic approach. We analyzed sequences from three molecular markers (cyt b, COI, and FGB) along with morphology data obtained from a sample of 64 individuals. Uni- and multivariate analyses of external and cranial measurements were conducted, alongside comparisons of external and cranial characteristics among species. Based on molecular and morphological differences, we describe a new species within the Molossus genus. This newly discovered species exhibits a broad distribution spanning the Paraná River basin across three distinct ecoregions. It is noteworthy that this species is pseudo-cryptic with respect to similar-sized species such as M. molossus and M. melini. Additionally, it is important to mention that all species in Argentina have overlapping distribution ranges. In summary, this study provides valuable insights into the diversity and distribution of Molossus bats in Argentina, employing molecular and morphological analyses. The discovery of a new species underscores the ongoing importance of comprehensive research efforts in understanding and conserving bat populations in the Neotropics.

Variability and influence of fisheries acoustic echogram annotations on machine learning applications

High-frequency echosounders are the workhorse in fisheries and marine ecological surveys. Due to the inherent complexity of biological aggregations and ambiguity in interpreting echoes from species of similar size and anatomical compositions, echogram annotation typically requires combining spectral information referencing scattering physics, biological ground-truth from nearby net-trawls, and empirical school morphology of specific fish species. Here, we investigate the variability of echogram annotations and its influence on machine learning applications using data from the biennial Pacific hake acoustic-trawl survey. Compared to many other fish species, hake tend to possess less defined school boundaries with variable acoustic features and often form mixed-species aggregations in the mesopelagic. Nonnegative matrix factorization and hierarchical clustering of volume backscattering strength (Sv) distributions across the 18, 38, and 120 kHz channels revealed a spectrum of annotation region types that reflect differences in morphological and acoustic features as well as differences in annotator style. This variability likely contributes to the observed variable segmentation behavior of deep learning models trained using this dataset. These results highlight the importance of considering the diversity of echogram annotation, its connection to scattering physics and the underlying aggregation composition, and the incorporation of such information in developing machine learning models.

Goliath is not the enemy: Fiddler crab species of similar size are stronger competitors than their larger adversaries in the climate change context

Many intertidal species are expanding their distribution limits towards the poles as a consequence of increased temperature due to climate change. At the same time, some intertidal habitats have been reduced due to rising sea levels. Fiddler crabs inhabit mangroves, and different species occupy well-established zones. Due to the restricted mangrove areas and consequent latitudinal expansion of the species, the distribution and density of fiddler crabs may be subject to change. The overlap forces several species to cohabit in a smaller territorial space. Fiddler crab species can vary in size, which could decisively affect territorial competition. Using Leptuca urguayensis as a reference, we tested how competing species of different sizes (larger size: L. thayeri and Minucapanema; similar size: L. cumulanta and L. leptodactyla) might interact in future climate change scenarios. First, we showed that within the territory of L. uruguayensis, the species L. cumulanta and L. thayeri occurred mainly in the lower mesolittoral zone, while L. leptodactyla and M.panema predominated in the upper mesolittoral zone. In a laboratory experiment, we evaluated whether the density and size of the heterospecific competitors could alter the agonistic behavior of Leptuca uruguayensis. Our results indicated that increasing the density can increase the agonistic behavior of L. uruguayensis with a greater intensity against species of a similar size. In a second field experiment, we demonstrated that the presence of a burrow enhances the intensity of agonistic interactions between L. uruguayensis and species of similar size. Therefore, in a scenario of territorial expansion of fiddler crabs due to climate change, it is expected that similarly sized species represent a greater competitive threat to populations of L. uruguayensis.

Spatial and temporal coexistence of medium-sized felines and their potential preys in Sierra Madre del Sur of Guerrero, México

Two species of similar size and trophic niche could not coexist in the same space and time unless the resources are diverse, abundant, and can be shared. In the Sierra Madre del Sur, Guerrero, Mexico, three felines of similar size coexist, Herpailurus yagouaroundi, Leopardus pardalis, and Leopardus wiedii. The objective of this research was to identify the spatiotemporal patterns that allow the coexistence of three felines and their potential preys, as well as to evaluate how the presence of humans and livestock influence their use of space and time. We hypothesized that the three felines coexist due to a differential use of time and space. Therefore, low or moderate overlap is expected, as well as a positive relationship with prey richness but negative regarding the presence of humans and livestock. Between 2009 and 2019, information was obtained on how the three feline species and their potential prey use time and space in eight landscapes with wide environmental variation using camera trapping. With a total sampling effort of 27,014 days/trap in 1,170 km2, 362 independent records of felids and 2,287 of 12 potential preys were obtained. Overlap in daily activity patterns (Δ) was estimated, and spatial co-occurrence was calculated using epsilon (Ɛ) values. Our results show that jaguarundi displayed a diurnal activity pattern and had an overlap of Δ = 0.22 with ocelot and Δ = 0.26 with margay; ocelot and margay were nocturnal with an activity overlap of Δ = 0.87. The spatial co-occurrence between the three felid species was positive: Ɛ = 2.61 between ocelot and margay, Ɛ = 3.22 between ocelot and jaguarundi; and Ɛ = 6 between jaguarundi and margay. The temporal overlap and spatial co-occurrence among felines showed a similar use of resources, and their distribution coincide with the one of some of their potential preys, may be related to predation strategies. Temporal overlap and spatial co-occurrence alone do not limit the coexistence of species; but the environmental differences of the landscapes do influence the variation and temporal dynamics of the felines studied in the Sierra Madre del Sur de Guerrero.

A bird's‐eye view: Evaluating drone imagery for the detection and monitoring of endangered and invasive day geckos

AbstractSpecies monitoring can be strongly limited by terrain accessibility, impeding our understanding of species ecology and thus challenging their conservation. This is particularly true for species living in the canopy, on cliffs or in dense vegetation. Remote sensing imagery may fill this gap by offering a cost‐effective monitoring approach allowing to improve species detection in inaccessible areas. We investigated the applicability of drone‐based monitoring for a Critically Endangered insular gecko (Phelsuma inexpectata) and two invasive alien gecko species representing a risk for the former (P. grandis and P. laticauda). We determined the approach distance before inducing behavioural response caused by the drone's presence. All three study species showed no escape behaviour to the drone's presence until very close distances (mean distance for P. inexpectata: 33.8 cm; P. grandis: 21.9 cm; P. laticauda: 26.4 cm). We then performed horizontal and vertical approaches with the drone, taking photos every meter starting at 10 m away from the canopy edge to determine an optimal distance for detection while ensuring species‐level identification. We examined a total of 328 photos. We found a bimodality in the number of detected geckos for two species, with different individuals recorded between short and intermediate distances. Therefore, we recommend taking photos at two distances of 2–2.5 and 5 m away from the canopy, ideally facing away from the sun and in low wind conditions. We encourage the application of our methodology for Phelsuma spp., but also for other species of similar size and ecology to improve detection in inaccessible areas.Abstract in French is available with online material.

Factors affecting gestation periods in elasmobranch fishes.

ABSTRACTGestation periods vary greatly across elasmobranch species. Differences in body size and body temperature (i.e. major determinants of metabolic rates) might explain such variation. Although temperature effects have been demonstrated for captive animals, body size effects remain undocumented. Moreover, whether metabolic rates of mothers or those of embryos affect gestation periods remains unclear. Because biological times generally scale with mass1−β, where β is metabolic scaling exponent (0.8–0.9 in fishes), we hypothesized that elasmobranch gestation periods would scale with mass0.1–0.2. We also hypothesized that regionally endothermic species with elevated metabolic rates should have shorter gestation periods than similar-sized ectothermic species if the metabolic rates of mothers are responsible. We compiled data on gestation periods for 36 elasmobranch species to show that gestation periods scale with M0.11 and m0.17, where M and m are adult female mass and birth mass, respectively. Litter size and body temperature also affected gestation periods. Our findings suggest that the body-mass dependence of metabolic rate explains some variations in elasmobranch gestation periods. Unexpectedly, regionally endothermic sharks did not have shorter gestation periods than their ectothermic counterparts, suggesting that the metabolic rates of embryos, which are likely ectothermic in all elasmobranch species, may be responsible. This article has an associated First Person interview with the first author of the paper.

A new species of Molossus (Chiroptera: Molossidae) from Argentina

Abstract Fourteen species of bats in the genus Molossus currently are recognized in the Neotropical region; only three are known from Argentina. Here, we describe a new species based on specimens collected in the province of Santa Fe, Argentina, in the Pampa ecoregion. The new species can be distinguished from its congeners by its general strong orange coloration, forearm length > 41 mm, dorsal hairs bicolor and long (~5 mm), infraorbital foramen laterally oriented, and long and forward-projected (pincer-like) upper incisors. The external and cranial morphology of the new species are described and comparisons made with other species of similar size and with those present in its distributional area. Wilcoxon tests and multivariate analyses (nonmetric multidimensional scaling ordination and PERMANOVA) were carried out to determine the morphometric differences between the new species and other seven species of Molossus. The species tree, estimated by *BEAST from the concatenation of mitochondrial and nuclear genes, suggests that Molossus sp. nov. is basal within the clade formed by {{M. aztecus, M. rufus}, {{M. currentium, M. pretiosus}, M. sinaloae}} with a posterior probability of 0.82.

Metal‐ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes

AbstractReversible dissociation of H−X bond (M−L+H−X→M(X)‐L(H); ) is an important step during pre‐activation, catalysis and possible deactivation of acid‐base cooperative pincer based transition metal catalysts (M−L). Herein we carried out a high‐throughput computational investigation of the thermodynamic stability of different adducts in various functionalized Mn(I) based pincer complexes. We used a combination of density functional theory (DFT) and density functional tight binding (DFTB) calculations to analyze of >700 (M(X)‐L(H)) intermediates based on functionalized variants of four pincer type ligand scaffolds derived from PCP, CNC, PNP and SNS ligands. We discovered linear scaling relations between of various species. Strongest correlations were found between species of similar size and chemical nature e. g. correlated best with and worst with . Such scaling relations can be useful for property based screening of catalysts and selection of (co)solvent/substrate/base for optimized reaction conditions. We also investigated the influence of the ligand backbone and the functionalization of donor and backbone sites in the ligand. Our analysis reveals the crucial role of the second coordination sphere functionalization for the reactivity of the complexes with impact in some cases exceeding that of the variation of the functional groups directly attached to the donor atoms.

Morphological and genetic analyses of Ostreopsis (Dinophyceae, Gonyaulacales, Ostreopsidaceae) species from Vietnamese waters with a re-description of the type species, O.siamensis.

Identification of species of the dinoflagellate genus Ostreopsis is difficult because several species have been poorly described, others misidentified in the literature, and the type species, O.siamensis, has not been described by contemporary taxonomic methods. In the present study, it is argued that Ostreopsis sp. 6 as described by previous authors is similar to the type species, and we offer an emended description of O.siamensis by LM, SEM, and molecular analyses of nuclear LSU and ITS rDNA based on material collected a few hundred kilometers from the type locality in the Gulf of Thailand and along the Vietnamese east coast. Ostreopsis siamensis is genetically different from the species reported as O.cf.siamensis in the literature and the latter should be described as a separate species. It is also concluded that with the poor knowledge of the morphological variability of many species of Ostreopsis, O.siamensis may not be distinguished from other similar-sized species by its morphological features, and hence molecular data are needed for reliable identification. The species Ostreopsis lenticularis and Ostreopsis cf. ovata were also found and described.

Locomotion and righting behavior of sea stars: a study case on the bat star Asterina stellifera (Asterinidae)

Introduction: The locomotion behavior of an organism involves the integration of aspects like body symmetry, sensory and locomotor systems. Furthermore, various ecological factors seem to be related to locomotion characteristics, such as foraging strategy, migration trends, response to predators and competitors, and environmental stress. Objective: To analyze locomotion and the influence of body symmetry in the crawling and righting movements of the sea star Asterina stellifera. Methods: We carried out laboratory experiments in aquariums in the presence/absence of water current and on a horizontal and vertical surface. Results: The speed is similar to speed in other species of similar size. Both the speed and linearity of displacement were independent of individual body size. A water current leads to faster crawling and straight paths, but there is no rheotaxis: streams do not affect locomotion. Speed and linearity of displacement were independent of individual body size. The displacement pattern described here may be an adaptation of organisms that present dense populations in communities with high prey abundance, as is the case of A. stellifera. Conclusions: Like other asteroids, this species did not show an Anterior/Posterior plane of symmetry during locomotion, or righting movement: it does not tend to bilaterality.

Can we use a functional trait to construct a generalized model for ungulate populations?

Ecologists have long desired predictive models that allow inference on population dynamics, where detailed demographic data are unavailable. Integral projection models (IPMs) allow both demographic and phenotypic outcomes at the level of the population to be predicted from the distribution of a functional trait, like body mass. In species where body mass markedly influences demographic rates, as is the rule among mammals, then IPMs provide not only opportunity to assess the population responses to a given environment, but also improve our understanding of the complex interplay between traits and demographic outcomes. Here, we develop a body-mass-based approach to constructing generalized, predictive IPMs for species of ungulates covering a broad range of body size (25-400kg). Despite our best efforts, we found that a reliable and general, functional, trait-based model for ungulates was unattainable even after accounting for among-species variation in both age at first reproduction and litter size. We attribute this to the diversity of reproductive tactics among similar-sized species of ungulates, and to the interplay between density-dependent and environmental factors that shape demographic parameters independent of mass at the local scale. These processes thus drive population dynamics and cannot be ignored. Environmental context generally matters in population ecology, and our study shows this may be the case for functional traits in vertebrate populations.

Factors influencing the activity patterns of two deer species and their response to predators in two protected areas in Indonesia

Facing change of environmental conditions, the activity rhythm of animals may habituate. Remote cameras were used to quantify Bawean deer and red muntjac activity patterns and to examined differences by season, sex and lunar cycle to respond predator presence, in Bawean Island and Ujung Kulon National Park, Indonesia. Photographs of Bawean deer (n = 118) were taken during March to November 2014 and for red muntjac (n = 4,142) were taken during January 2013 to July 2014. Data were analyzed by using Generalized Additive Models (GAMs) to test the relationship between activity patterns and the lunar cycle, further, the pattern of daily activity overlap between deer and their predators calculated by kernel density estimation. The number of captures by camera trapping were less for both sexes of both deer in wet season. Male and female Bawean deer were active throughout the day and night during all seasons, with several activity peaks during the 24h period, while male and female red muntjac show diurnal activity levels with higher peaks 1h after sunrise until 1h before sunset. There was no significant difference in activities between males and females for both deer. The amount of nocturnal activity corresponding to differences in nocturnal luminosity for Bawean deer varied, but not for the red muntjac. Free-roaming dog and Bawean deer presented opposite peak activities, while dhole as (the predator of the red muntjac) and red muntjac were both cathemeral. The differences between the two similar-sized species could be closely related to reduction of predation risk and increasing foraging success.

Activity patterns in a feline assemblage in south-west Mexico, and their relationship with prey species

AbstractSeveral species of neotropical felines are morphologically and ecologically similar, and are sympatric along large areas of their distribution. This requires mechanisms to allow their coexistence, such as temporal segregation of their activities. The aim of this study was to evaluate the relation between activity patterns of felines and their prey using camera trapping data and their seasonal variation in two tropical environments in south-western Mexico. ExceptingPuma concolor, activity patterns for each feline species did not differ significantly between seasons nor between vegetation types. Activity patterns did not differ significantly between species of similar size: mid-sized species had high activity pattern overlaps in the medium forest while large-sized species overlapped to a lesser extent in the cloud forest.Leopardus wiediidiffered from large-sized predators in its activity patterns. We recorded a relatively high temporal overlap between felines and their main prey species, particularly in the periods of maximum activity. We found no evidence of temporal segregation between the felines of the Sierra Norte region of Oaxaca and we suggest their coexistence is mediated by the selection of prey with different activity patterns.

Coexistence between wildlife and livestock is contingent on cattle density and season but not differences in body size.

Many studies on the coexistence of wildlife with livestock have focused primarily on similar-sized species. Furthermore, many of these studies have used dietary overlap as a measure of potential competition between interacting species and thus lack the important link between dietary overlap and any negative effects on a particular species–a prerequisite for competition. Consequently, the mechanisms that drive interspecific interactions between wildlife and cattle are frequently overlooked. To address this, we used an experimental setup where we leveraged different cattle stocking rates across two seasons to identify the drivers of interspecific interactions (i.e. competition and facilitation) between smaller-bodied oribi antelope and cattle. Using direct foraging observations, we assessed dietary overlap and grass regrowth, and also calculated oribi nutritional intake rates. Ultimately, we found that cattle compete with, and facilitate, smaller-bodied oribi antelope through bottom-up control. Specifically, cattle facilitated oribi during the wet season, irrespective of cattle stocking density, because cattle foraging produced high-quality grass regrowth. In contrast, during the dry season, cattle and oribi did not co-exist in the same areas (i.e. no direct dietary overlap). Despite this, we found that cattle foraging at high densities during the previous wet season reduced the dry season availability of oribi’s preferred grass species. To compensate, oribi expanded their dry season diet breadth and included less palatable grass species, ultimately reducing their nutritional intake rates. Thus, cattle competed with oribi through a delayed, across-season habitat modification. We show that differences in body size alone may not be able to offset competitive interactions between cattle and wildlife. Finally, understanding the mechanisms that drive facilitation and competition are key to promoting co-existence between cattle and wildlife.

Rusty Blackbird Habitat Selection and Survivorship during Nesting and Post-Fledging

Rusty blackbird (Euphagus carolinus) populations have declined dramatically since the 1970s and the cause of decline is still unclear. As is the case for many passerines, most research on rusty blackbirds occurs during the nesting period. Nest success is relatively high in most of the rusty blackbird’s range, but survival during the post-fledging period, when fledgling songbirds are particularly vulnerable, has not been studied. We assessed fledgling and adult survivorship and nest success in northern New Hampshire from May to August in 2010 to 2012. We also assessed fledgling and adult post-fledging habitat selection and nest-site selection. The likelihood of rusty blackbirds nesting in a given area increased with an increasing proportion of softwood/mixed-wood sapling stands and decreasing distances to first to sixth order streams. Wetlands were not selected for nest sites, but both adults and fledglings selected wetlands for post-fledging habitat. Fledglings and adults selected similar habitat post-fledging, but fledglings were much more likely to be found in habitat with an increasing proportion of softwood/mixed-wood sapling stands and were more likely to be closer to streams than adults. No habitat variables selected during nesting or post-fledging influenced daily survival rates, which were relatively low for adults over the 60-day study periods (males 0.996, females 0.998). Fledgling survival rates (0.89) were much higher than reported for species of similar size.

Mass-abundance scaling in avian communities is maintained after tropical selective logging.

Selective logging dominates forested landscapes across the tropics. Despite the structural damage incurred, selectively logged forests typically retain more biodiversity than other forest disturbances. Most logging impact studies consider conventional metrics, like species richness, but these can conceal subtle biodiversity impacts. The mass–abundance relationship is an integral feature of ecological communities, describing the negative relationship between body mass and population abundance, where, in a system without anthropogenic influence, larger species are less abundant due to higher energy requirements. Changes in this relationship can indicate community structure and function changes.We investigated the impacts of selective logging on the mass–abundance scaling of avian communities by conducting a meta‐analysis to examine its pantropical trend. We divide our analysis between studies using mist netting, sampling the understory avian community, and point counts, sampling the entire community.Across 19 mist‐netting studies, we found no consistent effects of selective logging on mass–abundance scaling relative to primary forests, except for the omnivore guild where there were fewer larger‐bodied species after logging. In eleven point‐count studies, we found a more negative relationship in the whole community after logging, likely driven by the frugivore guild, showing a similar pattern.Limited effects of logging on mass–abundance scaling may suggest high species turnover in logged communities, with like‐for‐like replacement of lost species with similar‐sized species. The increased negative mass–abundance relationship found in some logged communities could result from resource depletion, density compensation, or increased hunting; potentially indicating downstream impacts on ecosystem functions. Synthesis and applications. Our results suggest that size distributions of avian communities in logged forests are relatively robust to disturbance, potentially maintaining ecosystem processes in these forests, thus underscoring the high conservation value of logged tropical forests, indicating an urgent need to focus on their protection from further degradation and deforestation.

Differential feeding by common heterotrophic protists on four Scrippsiella species of similar size.

The dinoflagellate genus Scrippsiella is known to cause red tides. Mortality due to predation should be assessed in order to understand the population dynamics of Scrippsiella species. However, predation has been explored only in a few species. In this study, we examined feeding by common heterotrophic dinoflagellates Oxyrrhis marina, Gyrodinium dominans, Polykrikos kofoidii, Oblea rotunda, and Pfiesteria piscicida, and a ciliate Strombidinopsis sp., on four Scrippsiella species, of similar size, namely Scrippsiella acuminata, Scrippsiella donghaiensis, Scrippsiella lachrymosa, and Scrippsiella masanensis. All the heterotrophic protists tested could feed on all the four Scrippsiella species. However, the numerical and functional responses of P.kofoidii to the mean prey concentration were apparently different between the Scrippsiella species. With increasing prey concentration, the growth and ingestion rates of P.kofoidii on S.lachrymosa increased rapidly, and then saturated similar to those on S.acuminata, as previously reported, but those on S.donghaiensis continuously decreased. The cells of S.donghaiensis lysed P.kofoidii cells. In contrast, the growth and ingestion rates of P.kofoidii on S.masanensis were not significantly related to the prey concentration. At similarly high mean prey concentration, the growth and ingestion rates of G.dominans were significantly different between the four Scrippsiella species Therefore, differences in the growth and/or ingestion rates of G.dominans and P.kofoidii on the four Scrippsiella species might result in different ecological niches of both the predator and prey species.

Morphological and ecological convergence at the lower size limit for vertebrates highlighted by five new miniaturised microhylid frog species from three different Madagascan genera.

Miniaturised frogs form a fascinating but poorly understood amphibian ecomorph and have been exceptionally prone to taxonomic underestimation. The subfamily Cophylinae (family Microhylidae), endemic to Madagascar, has a particularly large diversity of miniaturised species which have historically been attributed to the single genus Stumpffia largely based on their small size. Recent phylogenetic work has revealed that several independent lineages of cophyline microhylids evolved towards highly miniaturised body sizes, achieving adult snout–vent lengths under 16 mm. Here, we describe five new species belonging to three clades that independently miniaturised and that are all genetically highly divergent from their relatives: (i) a new genus (Mini gen. nov.) with three new species from southern Madagascar, (ii) one species of Rhombophryne, and (iii) one species of Anodonthyla. Mini mum sp. nov. from Manombo in eastern Madagascar is one of the smallest frogs in the world, reaching an adult body size of 9.7 mm in males and 11.3 mm in females. Mini scule sp. nov. from Sainte Luce in southeastern Madagascar is slightly larger and has maxillary teeth. Mini ature sp. nov. from Andohahela in southeast Madagascar is larger than its congeners but is similar in build. Rhombophryne proportionalis sp. nov. from Tsaratanana in northern Madagascar is unique among Madagascar’s miniaturised frogs in being a proportional dwarf, exhibiting far less advanced signs of paedomorphism than other species of similar size. Anodonthyla eximia sp. nov. from Ranomafana in eastern Madagascar is distinctly smaller than any of its congeners and is secondarily terrestrial, providing evidence that miniaturisation and terrestriality may be evolutionarily linked. The evolution of body size in Madagascar’s microhylids has been more dynamic than previously understood, and future studies will hopefully shed light on the interplay between ecology and evolution of these remarkably diverse frogs.

The effect of ground surface rugosity on ant running speed is species-specific rather than size dependent

Foraging is one of the main reasons for ants to walk. Foraging speed is mainly dependent on morphological traits, but also on the surface structure. The size-grain hypothesis (SGH) suggests that (1) relative leg length should increase allometrically with body size, and (2) smaller, shorter legged species have an advantage with increasing habitat complexity in comparison to larger and longer legged species. In general, it is thought that leg length is a good predictor for running speed. We performed morphological analyses and running experiments with differently sized ant species along an artificial gradient of surface rugosity. We measured running speed, number of steps, body size and leg length to answer the question, if morphological traits can be used to predict the running speed of ants in complex habitats, as predicted by the SGH. We found that (1) leg length increased allometrically with body size, and that (2) the largest species were among the fastest and could sustain their speed with increasing surface rugosity. The smallest species with the relatively shortest legs were the fastest on the flattest surface, but their speed decreased rapidly with increasing rugosity. Leg length was not a good predictor for running speed. Similar-sized species responded idiosyncratically to high surface rugosity, which might be related to species-specific habitat preferences. Species-specific behavior or stride frequency influenced running speed strongly, which hampers precise predictions on their running speed, based on morphological traits exclusively.

Doubting dung: eDNA reveals high rates of misidentification in diverse European ungulate communities

Pellet counts are widely used to monitor ungulates but rely on the assumption that pellets of different species are correctly identified in the field. Recent studies question this assumption using DNA barcoding techniques to check field identification rates. For Europe, which is undergoing a rapid shift towards more diverse ungulate assemblages, such an assessment is still missing. Using DNA barcoding on 3889 fecal samples from nine ungulate species in four European countries, we found average field misidentification rates varied from 0.6% for horse (Equus ferus) to 41.1% for roe deer (Capreolus capreolus). Most identification errors occurred between similar-sized species from the same taxonomic family. For a subset of samples from Sweden, we looked at the effect of dung morphometry, observer experience, and season on species identification success. Dung morphometry clearly distinguished moose (Alces alces) but not red (Cervus elaphus), roe, and fallow deer (Dama dama). Experienced observers performed better than novices for red and fallow deer although still making significant identification errors (26% and 17% incorrectly identified). Identification success was higher during spring and winter ( overline{x} = 86%) than summer and autumn ( overline{x} = 74%). We question pellet counts as an accurate monitoring tool where similar-sized species coexist and monitoring relates to the whole community. For this increasingly common situation across Europe, DNA testing or camera traps may be a better alternative. Pellet counts remain useful where only few species with clearly different dung morphology coexist (e.g., moose and roe deer) or when focused on species with distinctive dung morphology (e.g., moose).