Emerging technologies based on the detection of electro-magnetic energy offer promising opportunities for sampling biodiversity. We exploit their potential bye showing here how they can be used in bat point counts - a novel method to sample flying bats - to overcome shortcomings of traditional sampling methods, and to maximise sampling coverage and taxonomic resolution of this elusive taxon with minimal sampling bias. We conducted bat point counts with a sampling rig combining a thermal scope to detect bats, an ultrasound recorder to obtain echolocation calls, and a near-infrared camera to capture bat morphology. We identified bats with the first dedicated identification key combining acoustic and morphological features, and compared bat point counts to the standard bat sampling methods of mist netting and automated ultrasound recording in three oil palm plantation sites in Indonesia, over nine survey nights. Based on rarefaction and extrapolation sampling curves, we show that bat point counts were the most time-efficient and effective method for sampling the oil palm species pool. Point counts sampled species that tend to avoid nets and those that are not echolocating, and thus cannot be detected acoustically. We identified some bat sonotypes with near-infrared imagery, and bat point counts revealed strong sampling biases in previous studies using capture-based methods, suggesting similar biases in other regions might exist. While capture-based methods allow to identify bats with absolute and internal morphometry, and unattended ultrasound recorders can effectively sample echolocating bats, bat point counts are a promising, and potentially competitive new tool for sampling all flying bats without bias and observing their behavior in the wild.

Climate change (CC) can alter the configuration of marine ecosystems, however ecosystem response and resilience to change are usually case-specific. The effect of CC on the demersal resources of the Aegean Sea (east Mediterranean Sea) was investigated during the past six decades applying a combination of multivariate analysis, non-additive modelling and the Integrated Resilience Assessment (IRA) framework. We focused on the study of: (i) the biological ‘system’ complex, using proxies of biomass (landings per unit of capacity) for 12 demersal taxa and (ii) the environmental ‘stressor’ complex, described by 12 abiotic variables. Pronounced changes have occurred in both the environmental and biological system over the studied period. The majority of the environmental stressors exhibited strikingly increasing trends (temperature, salinity, primary production indices) with values started exceeding the global historical means during late 1980s-early 1990s. It is suggested that the biological system exhibited a discontinuous response to CC, with two apparently climate-induced regime shifts occurring in the past 25 years. There is evidence for two fold bifurcations and four tipping points in the system, forming a folded stability landscape with three basins of attraction. The shape of the stability landscape for the Aegean Sea’s biological system suggests that while the initial state (1966-1991) was rather resilient to CC, absorbing two environmental step-changes, this was not the case for the two subsequent ones (intermediate: 1992-2002; recent: 2003-2016). Given the current trajectory of environmental change, it is highly unlikely that the biological system will ever return to its pre-1990s state, as it is entering areas of unprecedented climatic conditions and there is some evidence that the system may be even shifting towards a new state. Our approach and findings may be relevant to other marine areas of the Mediterranean and beyond, undergoing climate-driven regime shifts, and can assist to their adaptive management.

The population numbers of taiga bean goose (Anser fabalis fabalis) have halved during recent decades. Since this subspecies is hunted throughout most of its range, the decline is of management concern. Knowledge of the genetic population structure and diversity is important for guiding management and conservation efforts. Genetically unique subpopulations might be hunted to extinction if not managed separately, and any inbreeding depression or lack of genetic diversity may affect the ability to adapt to changing environments and increase the extinction risk. We used microsatellite and mitochondrial DNA markers to study the genetic population structure and diversity among taiga bean geese breeding within the Central flyway management unit using non-invasively collected feathers. We found some genetic structuring with the maternally inherited mitochondrial DNA between four geographic regions (ɸST = 0.11-0.20) but none with the nuclear microsatellite markers (all pairwise FST-values 0.002- 0.005). These results could be explained by female natal philopatry and male-biased dispersal, which completely homogenizes the nuclear genome. Therefore, the population could be managed as a single unit. Genetic diversity was still at a moderate level (average HE = 0.69) and there were no signs of past population size reductions, although significantly positive inbreeding coefficients in all sampling sites (FIS = 0.05-0.10) and high relatedness values (r = 0.60-0.86) between some individuals could indicate inbreeding. In addition, there was evidence of either incomplete lineage sorting or introgression from the pink-footed goose (A. brachyrhynchus). The current population is not under threat by genetic impoverishment but monitoring in the future is desirable.

Theory predicts that sexual selection should aid adaptation to novel environments, but empirical support for this idea is limited. Pathogens are a major driver of host evolution and, unlike abiotic selection pressures, undergo epidemiological and co-evolutionary cycles with the host involving adaptation and counteradaptation. Because of this, populations harbor ample genetic variation underlying immunity and the opportunity for sexual selection based on condition-dependent “good genes” is expected to be large. In this study, we evolved populations of Drosophila melanogaster in a 2-way factorial design manipulating sexual selection and pathogen presence, using a gram-negative insect pathogen Pseudomonas entomophila, for 14 generations. We then examined how the presence of sexual selection and the pathogen, as well as any potential interaction, affected the evolution of pathogen resistance. We found increased resistance to P. entomophila in populations that evolved under pathogen pressure, driven primarily by increased female survival after infection despite selection for resistance acting only on males over the course of experimental evolution. This result suggests that the genetic basis of resistance is in part shared between the sexes. We did not find any evidence of sexual selection aiding adaptation to pathogen, however, a finding contrary to the predictions of “good genes” theory. Our results therefore provide no support for a role for sexual selection in the evolution of immunity in this experimental system.

Adversity early in life can shape the reproductive potential of individuals through negative effects on health and lifespan. However, long-lived populations with multiple reproductive events may present alternative life history strategies to optimize reproductive schedules and compensate for shorter lifespans when experiencing adversities early in life. Here, we quantify the effects of major hurricanes and density-dependence as sources of early-life ecological adversity on the mean age-specific fertility, reproductive pace, and lifetime reproductive success (LRS) of Cayo Santiago rhesus macaque females, and explored demographic mechanisms for reproductive schedule optimization later in life. Females experiencing major hurricanes early in life exhibit a delayed reproductive debut, but maintain inter-birth intervals and show a higher mean fertility during prime reproductive ages relative to females experiencing no hurricanes. Increasing density at birth is associated to a decrease in mean fertility and LRS. When combined, our study reveals that early-life ecological adversities predict a delay-overshoot pattern in mean age-specific fertility that supports the maintenance of LRS. In contrast to predictive adaptive response models of accelerated reproduction, the long-lived Cayo Santiago population presents a novel reproductive strategy where females who experience major natural disasters early in life ultimately overcome their initial reproductive penalty with no overall negative fitness outcomes. Such strategy suggests that investing more energy into development and maintenance at younger ages allows long-lived females experiencing early-life ecological adversity to reproduce at a mean rate equivalent to that of a typical female cohort later in life.

Knowing the abundance of a population is a crucial component to assess its conservation status and develop effective conservation plans. For most cetaceans, abundance estimation is difficult given their cryptic and mobile nature, especially when the population is small and has a transnational distribution. In the Baltic Sea, the number of harbour porpoises (Phocoena phocoena) has collapsed since the mid-20th century and the Baltic Proper harbour porpoise is listed as Critically Endangered by the IUCN; however, its abundance remains unknown. Here, one of the largest ever passive acoustic monitoring studies was carried out by eight Baltic Sea nations to estimate the abundance of the Baltic Proper harbour porpoise for the first time. By logging porpoise echolocation signals at 298 stations during May 2011-April 2013, calibrating the loggers’ spatial detection performance at sea, and measuring the click rate of tagged individuals, we estimated an abundance of 66-1,143 individuals (95% CI, point estimate 490) during May-October within the population’s proposed management border. The small abundance estimate strongly supports that the Baltic Proper harbour porpoise is facing an extremely high risk of extinction, and highlights the need for immediate and efficient conservation actions through international cooperation. It also provides a starting point in monitoring the trend of the population abundance to evaluate the effectiveness of management measures and determine its interactions with the larger neighbouring Belt Sea population. Further, we offer evidence that design-based passive acoustic monitoring can generate reliable estimates of the abundance of rare and cryptic animal populations across large spatial scales.

Predators can strongly influence disease transmission and evolution, particularly when they prey selectively on infected hosts. Although selective predation has been observed in numerous systems, why predators select infected prey remains poorly understood. Here, we use a model of predator vision to test a longstanding hypothesis as to the mechanistic basis of selective predation in a Daphnia-microparasite system, which serves as a model for the ecology and evolution of infectious diseases. Bluegill sunfish feed selectively on Daphnia with a variety of parasites, particularly in water uncolored by dissolved organic carbon. The leading hypothesis for selective predation in this system is that infection-induced changes in the appearance of Daphnia render them more visible to bluegill. Rigorously evaluating this hypothesis requires that we quantify the effect of infection on the visibility of prey from the predator’s perspective, rather than our own. Using a model of the bluegill visual system, we show that the three common parasites, Metschnikowia bicuspidata, Pasteuria ramosa and Spirobacillus cienkowskii, increase the opacity of Daphnia, rendering infected Daphnia darker against the background of downwelling light. As a result of this increased brightness contrast, bluegill can see infected Daphnia at greater distances than uninfected Daphnia – between 19-33% further, depending on the parasite. Pasteuria and Spirobacillus also increase the chromatic contrast of Daphnia. Contrary to expectations, the visibility Daphnia was not strongly impacted by water color in our model. Our work generates hypotheses about which parasites are most likely affected by selective predation in this important model system and establishes visual models as a valuable tool for understanding ecological interactions that impact disease transmission.

Aims Volcanic eruptions play an important role in vegetation dynamics and its historical range of variability. However, large events are infrequent and eruptions with significant imprint in today vegetation occurred far in the past, limiting our understanding of ecological process. Volcanoes in southern Andes have been active during the last 10 ka, and support unique ecosystems such as the Araucaria-Nothofagus forest as part of the Valdivian Temperate Rainforest Hotspot. Araucaria is an endangered species, strongly fragmented and well adapted to disturbances. Yet it was suggested that volcanism might have increased the fragmentation of its populations. To provide an insight into the vegetation responses to past volcanic disturbances, a paleoecological study was conducted to assess the role of volcanic disturbance on the vegetation dynamics and if the current fragmentation has been caused by volcanism. Location Araucaria forest-steppe ecotone in northern Patagonia. Methods Pollen and tephra analysis from a sedimentary record. Results During the last 9 kyr, 39 tephrafall buried the vegetation around Lake Relem, more frequently between 4-2 ka. The vegetation was sensitive to small tephrafall but seldom caused significant changes. However, the large eruption of Sollipulli-Alpehue (~3 ka) might change the environmental conditions affecting severely the forest and grassland, as suggested by the pollen record. Ephedra dominated early successional stage, perhaps facilitating Nothofagus regeneration recovering original condition after ~500 years. Slight increase of pollen percentage from Araucaria and Nothofagus obliqua-type could be indicative of sparse biological legacies distributed in the landscape. The analysis showed that vegetation resisted without permanent changes, recovering relatively fast after the large eruption. Conclusion The relative stability of Araucaria pollen in the study area after several tephrafall suggests no change in its past geographical distribution at the current forest-steppe ecotone, thus I found no evidence that volcanic eruptions would have affected its current conservation status.

Changing climatic conditions and unsustainable land use are perceived as major threats to savannas worldwide. In the past, land use in African savannas was dominated by livestock-farming as one of the major economic products, which led to degraded, shrub encroached pastures in many regions. One response to this widespread degradation is a shift from land use dominated by cattle to strategies characterized by animal compositions with more mixed feeding regimes and higher browser proportions. However, the consequences for ecosystem properties and processes remain so far largely unclear. We used the ecohydrological, spatially explicit savanna model EcoHyD to assess the impacts of two contrasting, herbivore-related land use strategies on a Namibian savannah: grazing versus browsing herbivores. We varied the densities of grazers and browsers and determined the resulting composition and diversity of the plant community, total vegetation cover, soil moisture and water use by plants. Our results show that properties making plants less attractive to herbivores were best adapted to different densities of grazing (cattle) or browsing (pure browsing wildlife) animals. Also, properties leading to a competitive advantage under limited water availability were among the dominant ones. Overall, the results are in line with our expectations: we found heavy shrub encroachment with a loss of the perennial grass matrix under high stocking rates of cattle. A novel and unexpected result was that regardless of the density of browsers, grass cover and plant functional diversity were significantly higher in wildlife scenarios. This increased grass cover, but also the higher total cover improved water uptake by plants. We conclude that in contrast to grazers, browsers even in high densities do not lead to ecosystem degradation, but rather sustain a diverse vegetation with high cover of perennial grasses over a long time, implying also a lower erosion risk and higher provision of ecosystem services.

1. Animals exhibit varied life-history traits that reflect adaptive responses to their environments. For Arctic-breeding birds, traits like foraging guild, egg nutrient allocation, clutch size, and chick growth are predicted to be under increasing selection pressure due to rapid climate change and increasing environmental variability across high-latitude regions. 2. We compared four migratory birds (black brant [Branta bernicla nigricans], lesser snow geese [Chen caerulescens caerulescens], semipalmated sandpipers [Calidris pusilla], and Lapland longspurs [Calcarius lapponicus]) with varied life histories at an Arctic site in Alaska, USA, to understand how life-history traits help moderate environmental variability across different phases of the reproductive cycle. 3. We monitored aspects of reproductive performance related to the timing of breeding, reproductive investment, and chick growth from 2011–2018. 4. In response to early snow melt and warm temperatures, semipalmated sandpipers advanced their site arrival and bred in higher numbers, while brant and snow geese increased clutch sizes; all four species advanced their nest initiation dates. During chick rearing, longspur chicks were relatively resilient to environmental variation whereas warmer temperatures increased the growth rates of sandpiper chicks but reduced growth rates of snow goose goslings. These responses generally aligned with traits along the capital-income spectrum of nutrient acquisition and altricial-precocial modes of chick growth. Under a warming climate, the ability to mobilize endogenous reserves likely provides geese with relative flexibility to adjust the timing of breeding and the size of clutches. Warmer temperatures, however, may negatively affect the quality of herbaceous foods and slow gosling growth. 5. Species may possess traits that are beneficial during one phase of the reproductive cycle and others that may be detrimental at another phase, uneven responses that may be amplified with future climate warming. These results underscore the need to consider multiple phases of the reproductive cycle when assessing the effects of environmental variability on Arctic-breeding birds.

Acoustic communication allows animals to coordinate and optimize resource utilization in space. Cardioderma cor, the heart-nosed bat, is one of the few species of bats known to sing during nighttime foraging. Previous research found that heart-nosed bats react aggressively to song playback, supporting the territorial defense hypothesis of singing in this species. By tracking 14 individuals nightly during the dry seasons in Tanzania we further investigated the territorial defense hypothesis from an ecological standpoint, which predicts singing should be associated with exclusive areas containing a resource. We quantified the singing behavior of individuals at all perches used throughout the night. Using home range analysis tools, we quantified overall use night ranges and singing ranges, as well as areas used in early and later time periods at night. Males engaged in antiphonal singing from small (x̄ = 3.48 ± 2.71 ha), largely exclusive areas that overlapped with overall night ranges used for gleaning prey. Individuals varied in singing effort; however, all sang significantly more as night progressed. Subsequently, areas used earlier at night and overall use areas were both larger than singing areas. Individuals varied in singing strategies. Some males sang for long periods in particular trees and had smaller core areas, while others moved frequently among singing trees. The most prolific singers used more perches overall. The results support the hypothesis that acoustic communication repertoires evolved in support of stable foraging territory advertisement and defense in some bats.

Identification of phenotypic characteristics in reproductively successful individuals provides important insights into the evolutionary processes that cause range shifts due to environmental change. Female beluga whales (Delphinapterus leucas) from the Baffin Bay region (BB) of the Canadian Arctic in the core area of the species’ geographic range have larger body size than their conspecifics at the southern range periphery in Hudson Bay (HB). We investigated the mechanism for this north and south divergence as it relates to ovarian reproductive activity (ORA = total corpora) that combines morphometric data with ovarian corpora counted from female reproductive tracts. Based on the previous finding of reproductive senescence in older HB females, but not for BB whales, we compared ORA patterns of the two populations with age and body length. Female beluga whale ORA increased more quickly with age (63% partial variation explained) in BB than in HB (41%). In contrast, body length in HB female beluga whales accounted for considerably more of the total variation (12 vs 1%) in ORA compared to BB whales. We speculate that female HB beluga whale ORA was more strongly linked with body length due to higher population density resulting in food competition that favors the energetic advantages of larger body size during seasonal food limitations. Understanding the evolutionary mechanism of how ORA varies across a species’ range will assist conservation efforts in anticipating and mitigating future challenges associated with a warming planet.

1. Neighborhood competition models are powerful tools to measure the effect of interspecific competition. Statistical methods to ease the application of these models are currently lacking. 2. We present the forestecology package providing methods to i) specify neighborhood competition models, ii) evaluate the effect of competitor species identity using permutation tests, and iii) measure model performance using spatial cross-validation. Following Allen (2020), we implement a Bayesian linear regression neighborhood competition model. 3. We demonstrate the package’s functionality using data from the Smithsonian Conservation Biology Institute’s large forest dynamics plot, part of the ForestGEO global network of research sites. Given ForestGEO’s data collection protocols and data formatting standards, the package was designed with cross-site compatibility in mind. We highlight the importance of spatial cross-validation when interpreting model results. 4. The package features i) tidyverse-like structure whereby verb-named functions can be modularly “piped” in sequence, ii) functions with standardized inputs/outputs of simple features ‘sf‘ package class, and iii) an S3 object-oriented implementation of the Bayesian linear regression model. These three facts allow for clear articulation of all the steps in the sequence of analysis and easy wrangling and visualization of the geospatial data. Furthermore, while the package only has Bayesian linear regression implemented, the package was designed with extensibility to other methods in mind.

Both the Norwegian Spring Spawning herring (Clupea harengus) and the Northeast Arctic cod (Gadus morhua) are examples of how the overexploitation of marine fish populations was leading to a strong reduction even so stock collapse, with a strong decline in the associated fisheries, followed by a recovery. Cod and herring are both part of the Barents Sea ecosystem, which experienced major warming events in the early (1920-1940) and late 20th century. While the collapse or near collapse of these stocks seems to be linked to instability created by overfishing and climate, the difference of population dynamics before and after is not fully understood. In particular, it is unclear how the changes in population dynamics before and after the collapses are associated with biotic interactions. The combination of the availability of unique long-term time series for herring and cod makes it a well-suited study system to investigate the effects of collapse. We examine how species interactions may differently affect the herring and cod population dynamic before and after a collapse. Particularly we explore, using a GAM modelling approach, how herring could affect cod and reciprocally. We found that the effect on herring of cod biomass that was generally positive (i.e., covariation) became negative after the collapse (i.e., predation or competition). Likewise a change occurred for the cod, the juvenile herring biomass that had no effect before the collapse had a negative one after. Our results indicate that population collapses may lead to altered inter-specific interactions as well as altered response to abiotic environmental variations. While the stocks are at similar abundance levels before and after the collapses the system is potentially different in its functioning and may require different management action.

Undergraduate field experiences (UFEs) are a prominent element of science education across many disciplines; however, empirical data regarding the outcomes are often limited. UFEs are unique in that they take place in a field setting, are often interdisciplinary, and include diverse students. UFEs range from courses, to field trips, to residential research experiences, and thereby have the potential to yield a plethora of outcomes for undergraduate participants. The UFE community has expressed a strong interest in better understanding how to assess the outcomes of UFEs. In response, we developed a strategy by which practitioners can assess their UFE using an evidence-based, systematic and iterative approach. This essay guides practitioners through the steps of: identifying intended UFE outcomes, considering contextual factors, determining an explicit assessment approach, and using the information to inform next steps. We provide a table of common learning outcomes and potential assessment tools, vignettes to illustrate using the strategy, and suggestions for practical application of the strategy. We aim to support comprehensive and aligned assessment of UFEs, leading to more inclusive and reflective design, and ultimately improved student outcomes. We urge practitioners to move towards evidence-based advocacy for continued support of UFEs.

Historically, bird song complexity was thought to evolve primarily through sexual selection on males, yet in many species both sexes sing. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high latitudes. In contrast, we expect male-female song dimorphism and elaboration to be more similar at lower latitudes because longer breeding seasons and year-round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both selective pressures and sexes into account. We examined song elaboration and sexual dimorphism in 15 populations of nine fairy-wren species (Maluridae), a Southern Hemisphere clade with female song. We compared song elaboration and sexual song dimorphism to latitude and life history variables tied to sexual and social selection pressures and sex roles. Our results suggest that song elaboration evolved in part due to sexual competition in males: male song variability was more positively correlated with temperate breeding and greater breeding synchrony than female song. We also found strong evidence that sex-role similarity contributed to male-female song similarity: male and female songs were shorter and more similar when parental care was more equal and when male survival was high. Contrary to Northern Hemisphere latitudinal patterns, songs were less dimorphic at higher, temperate latitudes. These results suggest that selection on song can be sex-specific, with male song elaboration favored in contexts coincident with sexual selection. However, selection pressures associated with sex-role similarity also appear to constrain sex specific song evolution and song dimorphism.

In general, it is accepted that gap formation significantly affects the placement of scatter-hoarded seeds by small rodents, but the effects of different forest gap sizes on the seed-eating and scatter-hoarding behaviors of small rodents remain unclear. Thus, we examined the effects of a closed canopy forest, forest edge, and gaps with different sizes on the spatial dispersal of Quercus variabilis acorns and cache placement by small rodents using coded plastic tags in the Taihang Mountains, China. The seeds were removed rapidly and there were significant differences in the seed-eating and caching strategies between the stand types. We found that Q. variabilis acorns were usually eaten after being removed from the closed canopy forest and forest edges. By contrast, the Q. variabilis acorns in the forest gap stands were more likely to be scatter hoarded. The dispersal distances of Q. variabilis acorns were significantly longer in the forest gap plots compared with the closed canopy and forest edge plots. However, the proportions of scatter-hoarded seeds did not increase significantly as the gap size increased. In small-scale oak reforestation projects or research, creating small gaps to promote rodent-mediated seed dispersal may effectively accelerate forest recovery and successional processes.

Lake eutrophication and cyanobacterial blooms have become worldwide environmental issues. Under cyanobacterial blooms (especially Microcystis), Daphnia spp. can transfer beneficial information to their offspring in order to improve adaptability. Hox genes are important regulatory factors of transcription in metazoans, and are involved in the growth and development of organisms. In this study, the effects of Microcystis aeruginosa on Hox gene expression in the mothers and offspring of Daphnia similoides sinensis were investigated using a mixed diet of M. aeruginosa and Scenedesmus obliquus, in two clones. There were significant differences in the survival rates of D. similoides sinensis under different food treatments. Our results suggest that the offspring produced by D. similoides sinensis mother pre-exposed to toxic M. aeruginosa had stronger adaptability to M. aeruginosa than those produced by previously unexposed mother. Additionally, Hox gene expressions of D. similoides sinensis had obvious differences between clones under stress of toxic M. aeruginosa.