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241 terrestrial Preprints

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terrestrial behavioral ecology genetics ecosystem function invertebrate plants natural history ecosystem ecology description statistical molecular evolution laboratory comparative population ecology method development evolutionary ecology ecosystem selection analysis theory freshwater ecological experiment community ecology sequencing theoretical molecular genetics + show more tags
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Please note: These are preprints and have not been peer reviewed. Data may be preliminary.
Network analyses reveal the role of large snakes in connecting feeding guilds in a sp...
Daniela Coelho
Marcio Martins

Daniela Coelho

and 2 more

January 21, 2021
In ecological communities, interactions between consumers and resources lead to the emergence of ecological networks and a fundamental problem to solve is to understand which factors shape network structure. Empirical and theoretical studies on ecological networks suggest predator body size is a key factor structuring patterns of interaction. Because larger predators consume a wider resource range, including the prey consumed by smaller predators, we hypothesized that variation in body size favors the rise of nestedness. In contrast, if resource consumption requires specific adaptations, predators are expected to consume distinct sets of resources, thus favouring modularity. We investigate these predictions by characterising the trophic network of a species-rich Amazonian snake community (62 species). Our results revealed an intricate network pattern resulting from larger species feeding on higher diversity of prey, promoting nestedness, and specific lifestyles feeding on distinct resources, promoting modularity. Species removal simulations indicated that the nested structure is favored mainly by the presence of five species of the family Boidae, which because of their body size and generalist lifestyles connect modules in the network. Our study highlights the particular ways traits affect the structure of interactions among consumers and resources at the community level.
Multiple coping strategies maintain stability of a small mammal population in resourc...
Anne Polyakov
William Tietje

Ann Polyakov

and 5 more

January 20, 2021
In semi-arid environments, aperiodic rainfall pulses determine cycles of plant production and resource availability for higher trophic levels, creating strong bottom-up regulation. The influence of climatic factors on population vital rates often shapes the dynamics of small mammal populations in such resource-restricted environments. Using a 21-year biannual capture–recapture dataset (1993 to 2014), we examined the impacts of climatic factors on the population dynamics of the brush mouse (Peromyscus boylii) in semi-arid oak woodland of coastal-central California. We applied Pradel’s temporal symmetry model to estimate capture probability (p), apparent survival (φ), recruitment (f), and realized population growth rate (λ) of the brush mouse, and examined the effects of temperature, rainfall, and El Niño on these demographic parameters. The population was stable during the study period with a monthly realized population growth rate of 0.993 ± SE 0.032, but growth varied over time from 0.680 ± 0.054 to 1.450 ± 0.083. Monthly survival estimates averaged 0.817 ± 0.005 and monthly recruitment estimates averaged 0.175 ± 0.038. Survival probability and realized population growth were positively correlated with rainfall and negatively correlated with temperature. In contrast, recruitment was negatively correlated with rainfall and positively correlated with temperature. Brush mice maintained their population through multiple coping strategies, investing in high recruitment during warmer and drier periods and allocating more energy towards survival during cooler and wetter conditions. Although climatic change in coastal-central California will favor recruitment over survival, varying strategies may serve as a mechanism by which brush mice maintain resilience in the face of climate change. Our results indicate that rainfall and temperature are both important drivers of brush mouse population dynamics and will play a significant role in predicting the future viability of brush mice under a changing climate.
Termite mound cover and abundance respond to herbivore-mediated biotic changes in an...
Grace Charles
Corinna Riginos

Grace Charles

and 4 more

January 18, 2021
Both termites and large mammalian herbivores (LMH) are savanna ecosystem engineers that have profound impacts on ecosystem structure and function. Both of these savanna engineers modulate many common and shared dietary resources such as woody and herbaceous plant biomass, yet few studies have addressed how they impact one another. In particular, it is unclear how herbivores may influence the abundance of long-lived termite mounds via changes in termite dietary resources such as woody and herbaceous biomass. While it has long been assumed that abundance and areal cover of termite mounds in the landscape remains relatively stable, most data are observational, and few experiments have tested how termite mound patterns may respond to biotic factors such as changes in large herbivore communities. Here, we use a broad tree density gradient and two landscape-scale experimental manipulations—the first a multi-guild large herbivore exclosure experiment and the second a tree removal experiment– to demonstrate that patterns in termite mound abundance and cover are unexpectedly dynamic. Termite mound abundance, but not areal cover not significantly, is positively associated with experimentally controlled presence of cattle, but not wild mesoherbivores (15-1000 kg) or megaherbivores (elephants and giraffes). Herbaceous productivity and tree density, termite dietary resources that significantly affected by different LMH treatments, are both positive predictors of termite mound abundance. Experimental reductions of tree densities are associated with lower abundances of termite mounds. These results reveal a richly interacting web of relationships among multiple savanna ecosystem engineers and suggest that termite mound abundance and areal cover is intimately tied to herbivore-driven resource availability.
Ethanol resistance in Drosophila melanogaster has increased in parallel cold-adapted...
Quentin Sprengelmeyer
John E Pool

Quentin Sprengelmeyer

and 1 more

January 14, 2021
Understanding the genetic properties of adaptive trait evolution is a fundamental crux of biological inquiry that links molecular processes to biological diversity. Important uncertainties persist regarding the genetic predictability of adaptive trait change, the role of standing variation, and whether adaptation tends to result in the fixation of favored variants. Here, we use the recurrent evolution of enhanced ethanol resistance in Drosophila melanogaster during this species' worldwide expansion as a promising system to add to our understanding of the genetics of adaptation. We find that elevated ethanol resistance has evolved at least three times in different cooler regions of the species' modern range - not only at high latitude but also in two African high altitude regions - and that ethanol and cold resistance may have a partially shared genetic basis. Applying a bulk segregant mapping framework, we find that the genetic architecture of ethanol resistance evolution differs substantially not only between our three resistant populations, but also between two crosses involving the same European population. We then apply population genetic scans for local adaptation within our quantitative trait locus regions, and we find potential contributions of genes with annotated roles in spindle localization, membrane composition, sterol and alcohol metabolism, and other processes. We also apply simulation-based analyses that confirm the variable genetic basis of ethanol resistance and hint at a moderately polygenic architecture. However, these simulations indicate that larger-scale studies will be needed to more clearly quantify the genetic architecture of adaptive evolution, and to firmly connect trait evolution to specific causative loci.
Den characteristics and ecological significance of Marmota himalayana on the Qinghai-...
Shulin Wang
Fujiang Hou

Shulin Wang

and 1 more

January 14, 2021
Dens are places for cavernicolous animals to hibernate, reproduce, and avoid predators and harsh weather conditions, and thus they have a vital impact on their survival. M. himalayana is the main large cavernicolous rodent on the Qinghai-Tibet Plateau. The analysis of den traits and their ecological functions can reveal mechanisms by which marmots have adapted to their environment, which is important for further understanding the ecological significance of this species. From July to August 2019 (warm season), we used unmanned aerial vehicles to fly at low altitudes and slow speeds to locate 131 marmot burrows (45 on shaded slopes, 51 on sunny slopes, and 35 on flat areas) in the northeastern Qinghai-Tibet Plateau. We then measured the physical characteristics (den density, entrance size, first tunnel length, volume, orientation and plant characteristics near the den entrance) of these dens on site. The physical parameters of the M. himalayana dens showed that they function to protect the marmots from natural enemies and bad weather, provide good drainage, and maintain a stable microclimate around the entrance. This is a result of the marmot’s adaptation to the harsh environment (cold and humidity) of the Qinghai-Tibet Plateau.
Effects of landscape context on different groups of cavity-nesting bees, wasps and th...
Károly Lajos
Imre Demeter

Károly Lajos

and 4 more

January 13, 2021
In this study our aim was to assess the diversity and distribution of cavity-nesting solitary bees, wasps and the spider-hunting wasps' prey with regards to the influence of landscape context in a study area with relatively low human disturbance. The study took place between May and August 2018 at eight study sites in the hilly-mountainous central part of Romania, where the majority of the landscape is used for extensive farming or forestry. During the processing of the trap nest material, we recorded several parameters regarding the nests of different hymenopteran groups, the spider prey found inside these nests, and also tested the influence of the landscape structure surrounding the sites on both hymenopteran groups and spider prey. The majority of nests was built by the solitary wasp group of Trypoxylon, followed by Dipogon and Eumeninae. Solitary bees were much rarer, with Hylaeus being most common group. The groups showed partially differing size preferences concerning the diameter of the occupied reed stalks. In the nests of Trypoxylon we predominantly found spider prey from the family of Araneidae, followed by representatives from the families of Linyphiidae and Theridiidae. In contrast to Trypoxylon, the wasp group Dipogon preferred spider prey from the family of Thomisidae. Concerning the hymenopteran groups, significant effects of landscape structure were found on the number of both nests and brood cells of Eumeninae and on the number of brood cells of Hylaeus, Osmia and Trypoxylon. We also found that the diversity of Trypoxylon spider prey was significantly positively affected by an increasing proportion of grassland and negatively by an increasing proportion of woodland. Altogether, our study presents several new aspects concerning the diversity and distribution of solitary bees, wasps and the spider-hunting wasps' prey and also the effects of landscape context on these groups.
Deep learning based evaluation of the nightly behaviour of African ungulates in zoos
Max Hahn-Klimroth
Tobias Kapetanopoulos

Max Hahn-Klimroth

and 3 more

January 13, 2021
1. The description and analysis of animal behaviour over long periods of time is one of the most important challenges in ecology. However, most of these studies are limited due to the time and cost required by human observers. The collection of data via video recordings allows observation periods to be extended. However, their evaluation by human observers is very time-consuming. Progress in automated evaluation, using suitable deep learning methods, seems to be a forwardlooking approach to analyse even large amounts of video data in an adequate time frame. 2. In this study we present amulti-step convolutional neural network system for detecting animal behaviour states, which works with high accuracy. An important aspect of our approach is the introduction of model averaging and post-processing rules to make the system robust to outliers. 3. Our trained system achieves an in-domain classification accuracy of >0.92, which is improved to >0.96 by a postprocessing step. In addition, the whole system performs even well in an out-of-domain classification task with two unknown types, achieving an average accuracy of 0.93. We provide our system at https://github.com/Klimroth/Video-Action-Classifier-for-African-Ungulates-in-Zoos/tree/main/mrcnn_based so that interested users can train their own models to classify images and conduct behavioural studies of wildlife. 4. The use of a multi-step convolutional neural network for fast and accurate classification of wildlife behaviour facilitates the evaluation of large amounts of image data in ecological studies and reduces the effort of manual analysis of images to a high degree. Our system also shows that post-processing rules are a suitable way to make species-specific adjustments and substantially increase the accuracy of the description of single behavioural phases (number, duration). The results in the out-of-domain classification strongly suggest that our system is robust and achieves a high degree of accuracy even for new species, so that other settings (e.g. field studies) can be considered.
Intraspecific variations in life history traits of two pecky rice bug species from Ja...
Kazuhisa Yamasaki
Ken Tabuchi

Kazuhisa Yamasaki

and 7 more

January 11, 2021
The mirid bugs Stenotus rubrovittatus and Trigonotylus caelestialium, which cause pecky rice, have become a threat to rice cultivation in Asia. Damage caused by these pests has rapidly become frequent since around 2000 in Japan. Their expansion pattern is not simple, making it difficult to manage them by prediction. Some insects with wide distributions have locally adapted variations in life-history traits. We performed laboratory rearing experiments to assess the geographical scale of intraspecific variations in life-history traits of S. rubrovittatus and T. caelestialium. These were aimed at increasing the accuracy of occurrence estimates and the number of generations per year. These results were compared with previous research, and differences in development rates were observed between populations of different latitudes, but not of the same latitude. Finally, plotting the timing of adult emergence and the potential number of generations per year on maps with a 5-km grid revealed that they differed greatly locally at the same latitude. These maps can be used for developing more efficient methods of managing mirid bugs in integrated pest management.
History of canids in Chile and impacts on prey adaptations
Benjamín Silva
Meredith Root-Bernstein

Benjamín Silva

and 1 more

January 11, 2021
Artiodactyl prey species of Chile, especially guanacos (Lama guanicoe) are reported to be very susceptible to predation by pack hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack-hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies and hunting behaviour. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviours of guanacos: predator inspection of ambush predators, e.g. Puma concolor, and rushing at and kicking smaller cursorial predators, e.g. Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group-hunting canids east of the Andes, there were no native species creating group-hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.
Past, present and future geographic range of the relict Mediterranean and Macaronesia...
Montserrat Salvà-Catarineu
Angel Romo

Montserrat Salvà-Catarineu

and 7 more

January 07, 2021
Aim The aim of this study is to model the past, current and future distribution of J. phoenicea s.s., J. turbinata and J. canariensis, based on bioclimatic variables using a maximum entropy model (MaxEnt) in the Mediterranean and Macaronesian regions. Location Mediterranean and Macaronesian Taxon Cupressaceae, Juniperus Methods Data on the occurrence of the J. phoenicea complex was obtained from the GBIF, the literature, herbaria, and the authors’ field notes. The bioclimatic variables were obtained from the WorldClim database (http://worldclim.org/) and Paleoclim (http://www.paleoclim.org/). The climate data related to species localities were used for predictions of niches by implementation of MaxEnt and we evaluated the model with ENMeval. Results The potential niches of Juniperus phoenicea during the LIG, LGM and MH covered 30%, 10% and almost 100%, respectively, of the current potential niche. Climate warming could reduce potential niches by 30% and 90% in scenarios RCP2.6 and RCP8.5, respectively. The potential niches of Juniperus turbinata had a broad circum-Mediterranean and Canarian distribution during the LIG and the MH, extending its distribution during the LGM when it was found in more areas than at present; the predicted warming in scenario RCP2.6 and RCP8.5 could reduce the current potential niche by 30% and 50%, respectively. The model did not find suitable niches for J. canariensis during the LIG and the LGM, but during the MH its potential niche was 30% larger than at present. The climate warming scenario RCP2.6 indicates a reduction of the potential niche by 30%, while RCP8.5 does so by almost 60%. Main conclusions This research can provide information to increase the protection of the juniper forest and to try to counteract the phenomenon of local extinctions caused by anthropic pressure and climate changes.
Odor of achlorophyllous plants' seeds drives seed-dispersing ants
Mikihisa Yamada
Masaru Hojo

Mikihisa Yamada

and 2 more

January 06, 2021
Seed dispersal by ants is an important means of migration for plants. Although many 34 myrmecochorous plants have seeds containing elaiosome, a nutritional reward for ants, some 35 non-myrmecochorous seeds without elaiosomes are also dispersed by ant species. However, the 36 mechanism by which seeds without elaiosomes enable efficient dispersal by ants is scarcely 37 investigated. The seeds of the achlorophyllous and myco-heterotrophic herbaceous plant 38 Monotropastrum humile are very small without elaiosomes and require a fungal host for 39 germination and survival. We performed a bioassay using seeds of M. humile and the ant 40 Nylanderia flavipes to demonstrate ant-mediated seed dispersal. We also analyzed the volatile 41 odors emitted from M. humile seeds and conducted bioassays using dummy seeds coated with 42 seed volatiles. Although elaiosomes were absent from the M. humile seeds, the ants carried the 43 seeds to their nests. They also carried the dummy seeds coated with the seed volatile mixture to 44 the nest, and left some dummy seeds inside the nest and discarded the rest of the dummy seeds 45 outside the nest with a bias toward locations with moisture conditions, which might be 46 conducive to germination. We concluded that seeds of M. humile were dispersed by the ants, 47 and that seed odors were sufficient to induce directed dispersal even without elaiosomes. It is 48 probable that the fleshy fruit producing genus Monotropastrum evolved from the related 49 anemochorous genus Monotropa, which produces capsule fruit. This transformation from 50 anemochory to myrmecochory presents a novel evolutionary pathway toward ant-mediated seed 51 dispersal in an achlorophyllous plant.
Historical surveys reveal a long-term decline in muskrat populations
Carrie Sadowski
Jeff Bowman

Carrie Sadowski

and 1 more

January 06, 2021
The muskrat (Ondatra zibethicus) is an iconic species in Canada, valued for both its fur and its integral role in wetland ecosystems, and widely regarded for its perseverance. However, the resilience of this semi-aquatic mammal seems to be in question now as increasing evidence points to widespread population declines. Recent analyses of harvest data across North America suggest a reduction in their numbers, but this has not been widely corroborated by population surveys. In this study we replicated historic muskrat house count surveys at two large Great Lakes coastal wetlands and present confirmation that declines in muskrat harvest correspond to actual declines in muskrat abundance. At the Point Pelee National Park marsh and the Matchedash Bay-Gray Marsh wetland we found that mean muskrat house counts declined by 93% and 91% respectively between historic surveys 40-50 years ago and contemporary surveys over the past five years. The factors responsible for these dramatic declines remain unclear but there may be a relationship with changes in the habitat quality of these wetlands that have occurred over the same time frame. Not only is the loss of muskrats an issue for the resulting loss of the wetland ecosystem services they provide, but it may be an indication of broader marsh ecosystem degradation. As such, a scarcity of muskrats should be considered a red flag for the state of biodiversity in our wetlands. Continued surveys and ongoing research are needed to shed more light on the current status of muskrat populations and their marsh habitats across their native range. Keywords: Fur harvest; Muskrat; Ondatra; Population decline; Typha; Wetlands
Diel timing of nest predation changes across season in a subtropical shorebird
Martin Sládeček
Kateřina Brynychová

Martin Sládeček

and 10 more

January 06, 2021
Predation is the most common cause of nest failure in birds. While nest predation is relatively well studied in general, our knowledge is unevenly distributed across globe and taxa, with for example limited information on shorebirds breeding in sub-tropics. Importantly, we know fairly little about the timing of predation within a day and season. Here, we followed 499 nests of red-wattled lapwings (Vanellus indicus), a ground-nesting shorebird, to estimate a nest predation rate, and continuously monitored 231 of these nests for a sum of 2951 days to reveal how timing of predation changes over the day and season in a sub-tropical desert. We found that 324 nests hatched, 77 nests were predated, 38 failed for other reasons and 60 had unknown fate. Daily predation rate was 0.97% (95%CrI: 0.77% – 1.2%), which for a 30-day long incubation period translates into ~25% chance of nest being predated. Such predation rate is low compared to most other species. Predation events were distributed evenly across day and night, with a tendency for increased predation around sunrise. Predation rate and events were distributed evenly also across the season, although night predation was more common later in the season, perhaps because predators reduce their activity during daylight to avoid extreme heat. Indeed, nests were never predated upon when mid-day ground temperatures exceeded 45°C. Whether the activity pattern of predators indeed changes across the breeding season and whether the described predation patterns hold for other populations, species and geographical regions awaits future investigations.
Watching the days go by: asymmetric regulation of caterpillar development by changes...
Olle Lindestad
Inger Aalberg Haugen

Olle Lindestad

and 2 more

December 23, 2020
Many insects possess the plastic ability to either develop directly to adulthood, or enter diapause and postpone reproduction until the next year, depending on environmental cues (primarily photoperiod) that signal the amount of time remaining until the end of the growth season. These two developmental pathways often differ in co-adapted life history traits, e.g. with slower development and larger size in individuals headed for diapause. The developmental timing of these differences may be of adaptive importance: if pathways diverge late, the scope for phenotypic differences is smaller, whereas if pathways diverge early, the risk is higher of expressing a maladaptive phenotype if the selective environment changes. Here we explore the effects of changes in photoperiodic information during life on pupal diapause and associated life history traits in the butterfly Pararge aegeria. We find that both pupal diapause and larval development rate are asymmetrically regulated: while exposure to long days late in life (regardless of earlier experiences) was sufficient to produce nondiapause development and accelerate larval development accordingly, more prolonged exposure to short days was required to induce diapause and slow down pre-diapause larval development. While the two developmental pathways diverged early in development, development rates could be partially reversed by altered environmental cues. Meanwhile, pathway differences in body size were more inflexible, despite emerging late in development. Hence, in P. aegeria several traits are regulated by photoperiod, along subtly different ontogenies, into an integrated phenotype that strikes a balance between flexibility and phenotype-environment matching.
Investigating carnivore guild structure: Spatial and temporal relationships amongst t...
Pyae Kyaw
David Macdonald

Pyae Kyaw

and 7 more

December 16, 2020
At least nine felid species can co-occur in Southeast Asia, thus providing an unusual opportunity to investigate poorly known guild structure and the factors controlling it. Using camera-trap data, we quantified space use, temporal activity, and multi-dimensional niche overlap of tiger, clouded leopard, marbled cat, leopard cat, and Asiatic golden cat in Htamanthi Wildlife Sanctuary of Myanmar. We hypothesized that the spatio-temporal behaviour of smaller cats can reflect avoidance of the larger cats, which are both potential competitors and predators, and similar-sized guild members would partition their niches in space or time to reduce competition for resources. Our approach involved single-species occupancy modelling to identify site covariates, pairwise spatial overlap using Bayesian inference, and activity overlap with Kernel density estimation and multivariate analyses to test hypotheses. We found tiger and marbled cats were primarily diurnal, clouded leopard and leopard cat were nocturnal and golden cat exhibited cathemeral activity. We observed a complex pattern of guild assembly and potential competition involving strong niche displacement between the golden cat and marbled cat, but high overlap between the relatively similarly-sized pairing of clouded leopard and golden cat, and the markedly differently-sized tiger -- golden cat pairing. No significant evidence of mesopredator release was observed and the felid assembly in Northern Myanmar appeared to be partitioned mainly on a spatial, rather than temporal, dimension. Nonetheless, the temporal association between the three mesopredators was inversely related to the similarity in their body sizes. The insights into this felid guild revealed that the largest niche differences in the use of space and time occurred between the three smaller species, most evidently between the Asiatic golden cat-marbled cat pairing, followed by marbled cat - leopard cat pairing. This study offers new insight into carnivore guild assembly and, adds substantially to knowledge of five of the least known felids of conservation concern.
Diversity and selection of MHC class I genes in the Godlewski's bunting
Wei Huang
Boye Liu

Wei Huang

and 5 more

December 14, 2020
The major histocompatibility complex (MHC) is a multiple-copy immune gene family in vertebrates. Its genes are highly variable and code for antigen-presenting molecules. Characterization of MHC genes in different species and investigating the mechanisms that shape MHC diversity is an important goal in understanding the evolution of biological diversity. Here we developed a next generation sequencing (NGS) protocol to genotype the MHC class I genes of 326 Godlewski’s buntings (Emberiza godlewskii) sampled in the Western mountain area of Beijing from 2014 to 2016. A total of 184 functional alleles were identified, including both non-classical and classical alleles. Classical alleles could be clustered into nine supertypes. Compared with other passerine birds, the individual diversity of MHC class I genes in Godlewski’s buntings is intermediate. Ten amino acid sites in the antigen-binding domain showed signatures of positive selection and eight of them exhibit high amino acid polymorphism. These findings indicate the action of balancing selection and provide a framework for subsequent investigation of selection acting on MHC genes in Godlewski’s buntings.
Prevalence and intensity of avian malaria in a quail hybrid zone
Allison Roth
Nick Kaiser

Allison M Roth

and 3 more

December 14, 2020
Hybridization is a common and important stage in species formation in plants and animals. The evolutionary consequences of hybridization depend not only on reproductive compatibility between sympatric species, but also on factors like vulnerability to each other’s predators and parasites. We examine infection patterns of the blood parasite Haemoproteus lophortyx, a causative agent of avian malaria, at a site in the contact zone between California quail (Callipepla californica) and Gambel’s quail (C. gambelii). We tested whether species identity, sex, and year predicted infection status and intensity. While we found no effect of sex on the status or intensity of infection, we found differences in infection status and intensity across species and between years. The prevalence of infection in California and hybrid quail was lower than in Gambel’s quail. Once infected, however, California and hybrid quail had higher infection intensities than Gambel’s quail. California and hybrid quail exhibited no significant differences in prevalence or intensity of infection. These findings suggest that infection by H. lophortyx has the potential to influence species barrier dynamics in this system, however, more work is necessary to determine the exact evolutionary consequences of this blood parasite.
Impact of Phytophthora agathidicida infection on canopy and forest floor nutrient con...
Luitgard Schwendenmann
Beate Michalzik

Luitgard Schwendenmann

and 1 more

December 11, 2020
Kauri dieback, caused by Phytophthora agathidicida, is an ecosystem disturbance that poses a recent threat to the survival of kauri (Agathis australis) forests in New Zealand. Throughfall and stemflow play an important role in meeting the nutrient requirements of kauri forests. However, the effects of kauri dieback on canopy nutrient deposition remain unknown. Here we measured throughfall, stemflow and forest floor water yield and nutrient concentrations and fluxes (potassium, calcium, magnesium, manganese, silicon, sulphur, sodium, iron) of ten kauri trees differing in soil P. agathidicida DNA concentration and health status. We did not observe an effect of soil P. agathidicida DNA concentration on throughfall and stemflow water yield. Throughfall and forest floor nutrient concentrations and fluxes tended to decrease (up to 50%) with increasing soil P. agathidicida DNA concentration. Significant effects were found for potassium and manganese fluxes in throughfall, and calcium and silicon fluxes in forest floor leachate. The decline in nutrient input will have implications on plant nutrition, tree health and susceptibility to future pathogen infection in these ecologically unique kauri forests. Given our findings and the increasing spread of Phytophthora species worldwide, research on the underlying physiological mechanisms linking dieback and plant-soil nutrient fluxes is critical.
Capture method affects survival estimates and subsequent interpretation of ecological...
Katherine Brackel
Eric Michel

Katherine Brackel

and 4 more

December 10, 2020
Understanding what variables affect ungulate neonate survival is imperative to successful conservation and management of the species. Predation is commonly cited as a cause-specific source of mortality and ecological covariates often influence neonate survival. However, variation in survival estimates related to capture methodology has been documented with opportunistically captured neonates generally displaying greater survival than those captured via aid of vaginal implant transmitters (VITs), likely because of increased left truncation observed in the opportunistically captured datasets. Our goal was to assess if 3- and 6-month survival estimates varied by capture method while simultaneously assessing if capture method affected model selection and interpretation of ecological covariates for white-tailed deer neonates captured from three study sites in North Dakota and South Dakota, USA. We found survival varied by capture method for 3-month neonate survival with opportunistically captured neonates displaying up to 26% greater survival than their counterparts captured via VITs; however, this relationship was not present for 6-month survival. We also found model selection and subsequent interpretation of ecological covariates varied when analyzing datasets comprised of neonates captured via VITs, neonates captured opportunistically, and all neonates combined regardless of capture method. When interpreting results from our VIT only analysis for 3-month survival, we found survival varied by three time intervals and was lowest in the first two weeks of life. Capture method did not affect 6-month survival which was most influenced by total precipitation occurring during 3 – 8 weeks of a neonate’s life and percent canopy cover found at a neonate’s capture site. Our results support previous research that capture method must be accounted for when deriving survival estimates for ungulate neonates as it can impact derived estimates and subsequent interpretation of results.
Colony-level mechanisms of thermal tolerance regulation in the ant Ectatomma ruidum
Terrence McGlynn
Elizabeth Clifton

Terrence McGlynn

and 5 more

December 10, 2020
1. Insects spend energy to function in high temperature environments, and because social insects employ a division of labor, it is likely that thermal tolerance varies among individuals in the colony, based on the tasks that they perform. 2. Foraging workers of the ant Neotropical ant Ectatomma ruidum are known to show temporal differences in thermal tolerance, with greater tolerance in hot afternoons, relative to cool mornings. 3. We developed three hypotheses that can account for temporal differences in thermal tolerance among workers: Thermal Acclimation, Division of Labor, and Circadian Rhythm. 4. We tested these hypotheses with a pair of experiments that involved the measurement of thermal persistence of ants at a constant temperature in time-to-failure assays. The first experiment compared ants with different behavioral roles in colonies, and the second compared colonies subjected to thermal manipulations, then iteratively sampled at daily thermal maxima and minima. 5. We found robust support for the Circadian Rhythm and Thermal Acclimation Hypotheses, and little support for the Division of Labor Hypothesis. Colonies of this species integrate multiple mechanisms of adapting to thermal challenges including time of day, ambient temperature, and the behavioral context of individual workers.
Potential geographical distribution and environmental explanations of rare and endang...
Pengcheng Ye
Guangfu Zhang

Pengcheng Ye

and 5 more

December 07, 2020
In recent decades, due to the effect of climate change and the interference of human activities, the species habitat index fallen 2%. Studying the geographical distribution pattern and predicting the potential geographical distribution of species are of great significance for developing scientific and effective biodiversity conservation strategies. The purpose of this research is to predict the potential geographical distribution of 25 rare and endangered plant species in Northwest Yunnan, China on the grid map with a resolution of 0.05° × 0.05° and analyze the explanation capabilities of various environmental factors on the potential geographical distribution patterns of these species, and explore the main restrictive environmental factors. Initially, we employed the ecological niche model MaxEnt to predict the potential geographical distribution of target species. Following that, we overlaid the potential geographical distribution of each species, and we obtained the potential geographical distribution pattern of species richness on the spatial scale of the ecological niche model with a resolution of 0.05° × 0.05°. Ultimately, we also adopted geographically weighted regression (GWR) model to investigate the explanation capabilities of various environmental parameters on the potential distribution patterns. The results showed that the average AUC value of each species was between 0.80 and 1.00, which indicated that the simulation precision of the MaxEnt model for each species was good or excellent. Besides, the potential distribution areas of these species were between 826.33 km2 and 44,963.53 km2. In addition, the average contribution values of the annual precipitation (Bio12), precipitation of coldest quarter (Bio19) and population density (Pop) were 25.92%, 15.86% and 17.95%, respectively. Moreover, the goodness of fit R2 and AIC value of the water model were 0.88 and 7,703.82, respectively, which indicated the water factor largely influenced the potential distribution of these species. The results of this study would be helpful for implementing long-term conservation and reintroduction for these species.
Phylogeographic study of the Bufo gargarizans species complex, with emphasis on North...
Chang-hoon Lee
Jonathan FONG

Chang-hoon Lee

and 7 more

December 01, 2020
We conduct a phylogeographic and population genetic study of the Asiatic Toad (Bufo gargarizans) to understand its evolutionary history, and the influence of geology and climate of the region. A total of 292 individuals from 94 locations were genotyped for two mitochondrial DNA loci (cytb, ND2 gene) and five nuclear introns (Sox9-2, Rho-3, CCNB2-3, UCH-2, DBI-2). We performed a suite of phylogenetic, population genetic, and divergence dating analyses. The phylogenetic trees constructed using mitochondrial loci inferred B. gargarizans being divided into two major groups: West (China mainland) and Northeast (Northeast China, Russia and Korean Peninsula). As with previous studies of this species, we recover population genetic structure not tied to geographic region. Additionally, we discover a new genetic clade restricted to Northeast Asia that points towards the Korean Peninsula being a glacial refugium during the Pleistocene. The weak phylogeographic pattern of B. gargarizans is likely the result of multiple biological, anthropogenic, and historical—robust dispersal abilities as a consequence of physiological adaptations, human translocation, geologic activity, and glacial cycles of the Pleistocene. We highlight the complex geologic and climatic history of Northeast Asia and encourage further research to understand its impact on the biodiversity in the region.
Quantifying Rapid Urbanization and its impact on Urban Green Spaces: Directional and...
Eyasu markos woldesemayat

Eyasu markos woldesemayat

November 30, 2020
Addis Ababa, the capital of Ethiopia, is urbanizing rapidly in recent years mainly through the destruction of environmental resources. This study aimed at the dynamics of urban green spaces (UGS). Remote Sensing and Geographical Information System (GIS) was used to extract land use and land cover data. The Landscape Expansion Index (LEI) was employed to measure urban growth patterns. The result showed that a more noticeable growth was observed in the peri-urban zone (40.1km2 to 176.1km2), followed by the inner urban zone (from 67.1km2 to 105km2). The expansion in the urban core zone was marginal and followed a non-unidirectional trend i.e. increased in the first period (1989-1999) and second period (1999-2009) by (0.11% and 4.2%), while decreased in the third period (2009-2019) by 3.6%. The result for LEI dynamics showed that the city experienced a pronounced outlying growth (98%) pattern, while edge expansion and infilling growth were insignificant. Conversely, the UGS declined in the inner urban zone by (18.03%), (28.61%) and (18.97%) in the first, second, and third periods. Similarly, in the peri-urban zone, the UGS persistently declined by (11.5%), (17.1%) and, (28.03%). The directional analysis showed that urban areas significantly expanded in SEE, SSE, SSW, and NEE with a net increase of 5.35, 4.4 km, 2.83, and 2.3 km2/year, respectively. Conventional large-scale /citywide/ dynamics investigations are not robust enough to represent the actual magnitude and directions of change, while the zonal and directional study is more effective in characterizing the Spatio-temporal dynamics for better urban planning towards.
Geographic variation in the skulls of the horseshoe bats, Rhinolophus simulator and R...
Gregory Mutumi
David Jacobs

Gregory Mutumi

and 2 more

November 25, 2020
The relative contributions of adaptation and drift to morphological diversification of the crania of echolocating mammals was investigated using two horseshoe bat species, Rhinolophus simulator and R. cf. simulator as test cases. We used 3D geometric morphometrics to compare the shapes of skulls of the two lineages collected at various localities in southern Africa. Shape variation was predominantly attributed to selective forces; the between population variance (B) was not proportional to the within population variance (W). Modularity was evident in the crania of R. simulator but absent in the crania of R. cf. simulator and the mandibles of both species. The skulls of the two lineages thus appeared to be under different selection pressures, despite the overlap in their distributions. Selection acted mainly on the nasal dome region of R. cf. simulator whereas selection acted more on the cranium and mandibles than on the nasal domes of R. simulator. Probably the relatively higher echolocation frequencies used by R. cf. simulator, the shape of the nasal dome, which acts as a frequency dependent acoustic horn, is more crucial than in R. simulator, allowing maximization of the intensity of the emitted calls and resulting in comparable detection distances. In contrast, selection pressure is probably more pronounced on the mandibles and cranium of R. simulator to compensate for the loss in bite force because of its elongated rostrum. The predominance of selection probably reflects the stringent association between environment and the optimal functioning of phenotypic characters associated with echolocation and feeding in bats.
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