Fatty Acid Amide Hydrolase and Cannabinoid Receptor Type 1 Genes Regulation is Modulated by Social Isolation in Rats

Social isolation is a state of lack of social connections, involving the modulation of different molecular signalling cascades and associated with high risk of mental health issues. To investigate if and how gene expression is modulated by social experience at the central level, we analyzed the effects of 5 weeks of social isolation in rats focusing on endocannabinoid system genes transcription in key brain regions involved in emotional control. We observed selective reduction in mRNA levels for fatty acid amide hydrolase (Faah) and cannabinoid receptor type 1 (Cnr1) genes in the amygdala complex and of Cnr1 in the prefrontal cortex of socially isolated rats when compared to controls, and these changes appear to be partially driven by trimethylation of Lysine 27 and acetylation of Lysine 9 at Histone 3. The alterations of Cnr1 transcriptional regulation result also directly correlated with those of oxytocin receptor gene. We here suggest that to counteract the effects of SI, it is of relevance to restore the endocannabinoid system homeostasis via the use of environmental triggers able to revert those epigenetic mechanisms accounting for the alterations observed.

Fragmented forest affects the southern black-horned capuchin (Sapajus nigritus cucullatus) in the Argentinean Atlantic Forest

The southern black-horned capuchin, Sapajus nigritus cucullatus, is considered Near Threatened on the IUCN Red List and Vulnerable in Argentina. The species is mainly threatened by habitat loss and fragmentation. The aim of this study was to compare range size, group size, and density in S. n. cucullatus groups between areas of continuous and fragmented habitat in the Atlantic Forest in Argentina. The study was carried out in two areas in northern Misiones province, one continuous and one anthropogenic fragment. Fieldwork was carried out for 5 days each month from November 2019 to March 2020 and from November 2020 to March 2021. SARS-CoV-2 restrictions meant we could not survey in the intervening period. Group counts were made on existing trails and subsequent group follows. We georeferenced encounters and follows to estimate home range sizes. We calculated density based on home range modeling using 100% minimum convex polygons (MCP), and compared these using generalized linear models (GLM). Smaller groups and lower density of S. n. cucullatus were found in continuous forest, with group sizes between 12 and 23 individuals, and density of 0.14 ind/ha, whereas in the fragmented forest, group sizes were between 32 and 36, with density of 0.62 ind/ha (n = 107; zero-inflated negative binomial regression [ZINB], p < 0.05). The higher density in forest fragments may be due to reduced dispersal ability. This work highlights data on species plasticity that could contribute to the development of conservation management strategies for S. n. cucullatus and its habitat.

Light pollution and habitat fragmentation in the grey mouse lemur

Light pollution, by changing organisms' behavior, affects locomotion, migration and can ultimately fragment the habitat. To investigate the effects of light pollution on habitat fragmentation, we conducted an experimental study on a nocturnal and photosensitive primate, the grey mouse lemur (Microcebus murinus). Twelve males were housed individually in an apparatus with two cages connected by two corridors, opaque and transparent. During 4 nights, the transparent corridor was illuminated by specific light intensities: 0 lx, 0.3 lx, 20 lx and 51.5 lx corresponding respectively to total darkness, full moon, minimal intensity recommended by the European standard EN-13201 on public lighting, and to light pollution recorded in an urban area. Each night, general activity, use of corridors and cage occupancy were recorded using an infrared camera. For the first time in a nocturnal primate, results demonstrate that light pollution changes the preference of use of corridors, modifies the locomotor pattern and limits the ability of animals to efficiently exploit their environment according to a light intensity-dependent relationship. However, results indicate that a dark corridor allows partial compensation partly preserving general activities. This study highlights the necessity to consider light pollution during the implementation of conservation plans and the relevance of nocturnal frames.

Anticipated effects of abiotic environmental change on intraspecific social interactions

Social interactions are ubiquitous across the animal kingdom. A variety of ecological and evolutionary processes are dependent on social interactions, such as movement, disease spread, information transmission, and density-dependent reproduction and survival. Social interactions, like any behaviour, are context dependent, varying with environmental conditions. Currently, environments are changing rapidly across multiple dimensions, becoming warmer and more variable, while habitats are increasingly fragmented and contaminated with pollutants. Social interactions are expected to change in response to these stressors and to continue to change into the future. However, a comprehensive understanding of the form and magnitude of the effects of these environmental changes on social interactions is currently lacking. Focusing on four major forms of rapid environmental change currently occurring, we review how these changing environmental gradients are expected to have immediate effects on social interactions such as communication, agonistic behaviours, and group formation, which will thereby induce changes in social organisation including mating systems, dominance hierarchies, and collective behaviour. Our review covers intraspecific variation in social interactions across environments, including studies in both the wild and in laboratory settings, and across a range of taxa. The expected responses of social behaviour to environmental change are diverse, but we identify several general themes. First, very dry, variable, fragmented, or polluted environments are likely to destabilise existing social systems. This occurs as these conditions limit the energy available for complex social interactions and affect dissimilar phenotypes differently. Second, a given environmental change can lead to opposite responses in social behaviour, and the direction of the response often hinges on the natural history of the organism in question. Third, our review highlights the fact that changes in environmental factors are not occurring in isolation: multiple factors are changing simultaneously, which may have antagonistic or synergistic effects, and more work should be done to understand these combined effects. We close by identifying methodological and analytical techniques that might help to study the response of social interactions to changing environments, highlight consistent patterns among taxa, and predict subsequent evolutionary change. We expect that the changes in social interactions that we document here will have consequences for individuals, groups, and for the ecology and evolution of populations, and therefore warrant a central place in the study of animal populations, particularly in an era of rapid environmental change.

The role of habitat configuration in shaping animal population processes: a framework to generate quantitative predictions

By shaping where individuals move, habitat configuration can fundamentally structure animal populations. Yet, we currently lack a framework for generating quantitative predictions about the role of habitat configuration in modulating population outcomes. To address this gap, we propose a modelling framework inspired by studies using networks to characterize habitat connectivity. We first define animal habitat networks, explain how they can integrate information about the different configurational features of animal habitats, and highlight the need for a bottom–up generative model that can depict realistic variations in habitat potential connectivity. Second, we describe a model for simulating animal habitat networks (available in the R package AnimalHabitatNetwork), and demonstrate its ability to generate alternative habitat configurations based on empirical data, which forms the basis for exploring the consequences of alternative habitat structures. Finally, we lay out three key research questions and demonstrate how our framework can address them. By simulating the spread of a pathogen within a population, we show how transmission properties can be impacted by both local potential connectivity and landscape-level characteristics of habitats. Our study highlights the importance of considering the underlying habitat configuration in studies linking social structure with population-level outcomes.

Physiological implications of life at the forest interface of oil palm agriculture: blood profiles of wild Malay civets (Viverra tangalunga)

Agricultural development is a major threat to global biodiversity, and effective conservation actions are crucial. Physiological repercussions of life alongside human-modified landscapes can undermine adaptable species' health and population viability; however, baseline data are lacking for many wildlife species. We assessed the physiological status of a generalist carnivore, the Malay civet (Viverra tangalunga), persisting within an extensively human-modified system in Sabah, Malaysian Borneo. We characterized hematology and serum biochemistry panels from civets sampled across a mosaic landscape comprising tropical forest fragments and oil palm plantations. Intra-population variation in certain blood parameters were explained by expected biological drivers such as sex, age category and sampling season. Furthermore, we determined several erythrocyte measures, immune cell counts and dietary biochemistry markers significantly varied with proximity to oil palm plantation boundaries. These findings were supported by a case study, whereby blood profiles of GPS collared male civets were contrasted based on their exclusive use of forests or use of oil palm plantations. These data provide robust and valuable first insights into this species' physiological status and suggest agricultural landscapes are impacting the persisting population.

Urban Hedgehog Behavioural Responses to Temporary Habitat Disturbance versus Permanent Fragmentation

Anthropogenic activities can result in both transient and permanent changes in the environment. We studied spatial and temporal behavioural responses of European hedgehogs (Erinaceus europaeus) to a transient (open-air music festival) and a permanent (highly fragmented area) disturbance in the city of Berlin, Germany. Activity, foraging and movement patterns were observed in two distinct areas in 2016 and 2017 using a "Before & After" and "Control & Impact" study design. Confronted with a music festival, hedgehogs substantially changed their movement behaviour and nesting patterns and decreased the rhythmic synchronization (DFC) of their activity patterns with the environment. These findings suggest that a music festival is a substantial stressor influencing the trade-off between foraging and risk avoidance. Hedgehogs in a highly fragmented area used larger home ranges and moved faster than in low-fragmented and low-disturbed areas. They also showed behaviours and high DFCs similar to individuals in low-fragmented, low disturbed environment, suggesting that fragmentation posed a moderate challenge which they could accommodate. The acute but transient disturbance of a music festival, therefore, had more substantial and severe behavioural effects than the permanent disturbance through fragmentation. Our results are relevant for the welfare and conservation measure of urban wildlife and highlight the importance of allowing wildlife to avoid urban music festivals by facilitating avoidance behaviours.

Effect of ecological factors on fine-scale patterns of social structure in African lions

Environmental variations can influence the extent to which individuals interact with other individuals by changing the value of grouping. It is well known that many species can form and disband groups, often in response to the distribution and abundance of resources. While previous studies showed that resources influence the broad-scale structure of animal groups, knowledge gaps remain on whether they affect fine-scale patterns of association among individuals within groups. We quantify association patterns in African lions while simultaneously monitoring the abundance and distribution of prey. We test how social and ecological factors, including individual trait (age, sex, reproductive state) similarity and prey availability (prey abundance, dispersion, herd size and body size) affect within-pride social structure in African lions. We found that individual decisions about associates depended on resource availability with individuals associating equally across all members of the pride when prey herds were scarce, aggregated or large bodied, and associating more exclusively (in subgroups of preferred associates) when prey herds were abundant, dispersed or small bodied. Individuals within lion prides seemed to be buffering against changes in prey availability by modulating their strength and density of connections with conspecifics when prides split into subgroups. The strength and density of connections among individuals within subgroups was greater when prey herds were large and lower when prey herds were dispersed or are large bodied. Our findings suggest that individual lions are making social decisions at both the subgroup level and the pride level, with decisions representing putatively fitness-enhancing strategies. Individuals were typically shifting between having few strong connections and having many weaker connections depending on prevailing ecological conditions, with prey abundance, dispersion and body size having the greatest impact on decisions about splitting into subgroups. The maintenance of connections within prides and subgroups in the face of ecological change suggests that the fission-fusion nature of lion prides might be essential for the long-term maintenance of social connections even when short-term conditions do not allow them. More broadly, our study reveals how fission-fusion dynamics and ecological factors can simultaneously have an effect on animals across multiple levels of sociality.

Genetic consequences of social structure in the golden-crowned sifaka

Many species are structured in social groups (SGs) where individuals exhibit complex mating strategies. Yet, most population genetic studies ignore SGs either treating them as small random-mating units or focusing on a higher hierarchical level (the population). Empirical studies acknowledging SGs have found an overall excess of heterozygotes within SGs and usually invoke inbreeding avoidance strategies to explain this finding. However, there is a lack of null models against which ecological theories can be tested and inbreeding avoidance quantified. Here, we investigate inbreeding (deviation from random mating) in an endangered forest-dwelling pair-living lemur species (Propithecus tattersalli). In particular, we measure the inbreeding coefficient (F_IS) in empirical data at different scales: SGs, sampling sites and forest patches. We observe high excess of heterozygotes within SGs. The magnitude of this excess is highly dependent on the sampling scheme: while offspring are characterised by a high excess of heterozygotes (F_IS < 0), the reproductive pair does not show dramatic departures from Hardy-Weinberg expectations. Moreover, the heterozygosity excess disappears at larger geographic scales (sites and forests). We use a modelling framework that incorporates details of the sifaka mating system but does not include active inbreeding avoidance mechanisms. The simulated data show that, although apparent "random mating" or even inbreeding may occur at the "population" level, outbreeding is maintained within SGs. Altogether our results suggest that social structure leads to high levels of outbreeding without the need for active inbreeding avoidance mechanisms. Thus, demonstrating and measuring the existence of active inbreeding avoidance mechanisms may be more difficult than usually assumed.

Demographic population structure of black howler monkeys in fragmented and continuous forest in Chiapas, Mexico: Implications for conservation

For wild primates, demography studies are increasingly recognized as necessary for assessing the viability of vulnerable populations experiencing rapid environmental change. In particular, anthropogenic changes such as habitat loss and fragmentation can cause ecological and behavioral changes in small, isolated populations, which may, over time, alter population density and demographic structure (age/sex classes and group composition) in fragment populations relative to continuous forest populations. We compared our study population of Endangered black howler monkeys (Alouatta pigra) in 34 forest fragments around Palenque National Park (PNP), Mexico (62 groups, 407 individuals), to the adjacent population in PNP, protected primary forest (21 groups, 134 individuals), and to previous research on black howlers in fragments in our study area (18 groups, 115 individuals). We used χ² and Mann-Whitney U tests to address the questions: (a) what is the current black howler demographic population structure in unprotected forest fragments around PNP? (b) How does it compare to PNP's stable, continuous population? (c) How has it changed over time? Compared to the PNP population, the fragment populations showed higher density, a significantly lower proportion of multimale groups, and significantly fewer adult males per group. The population's age/sex structure in the fragmented landscape has been stable over the last 17 years, but differed in a higher proportion of multifemale groups, higher density, and higher patch occupancy in the present. In the context of conservation, some of our results may be positive as they indicate possible population growth over time. However, long-term scarcity of adult males in fragments and associated effects on population demographic structure might be cause for concern, in that it may affect gene flow and genetic diversity. The scarcity of adult males might stem from males experiencing increased mortality while dispersing in the fragmented landscape, whereas females might be becoming more philopatric in fragments.

Dispersal and genetic structure in a tropical small mammal, the Bornean tree shrew (Tupaia longipes), in a fragmented landscape along the Kinabatangan River, Sabah, Malaysia

Background

Constraints in migratory capabilities, such as the disruption of gene flow and genetic connectivity caused by habitat fragmentation, are known to affect genetic diversity and the long-term persistence of populations. Although negative population trends due to ongoing forest loss are widespread, the consequence of habitat fragmentation on genetic diversity, gene flow and genetic structure has rarely been investigated in Bornean small mammals. To fill this gap in knowledge, we used nuclear and mitochondrial DNA markers to assess genetic diversity, gene flow and the genetic structure in the Bornean tree shrew, Tupaia longipes, that inhabits forest fragments of the Lower Kinabatangan Wildlife Sanctuary, Sabah. Furthermore, we used these markers to assess dispersal regimes in male and female T. longipes.

Results

In addition to the Kinabatangan River, a known barrier for dispersal in tree shrews, the heterogeneous landscape along the riverbanks affected the genetic structure in this species. Specifically, while in larger connected forest fragments along the northern riverbank genetic connectivity was relatively undisturbed, patterns of genetic differentiation and the distribution of mitochondrial haplotypes in a local scale indicated reduced migration on the strongly fragmented southern riverside. Especially, oil palm plantations seem to negatively affect dispersal in T. longipes. Clear sex-biased dispersal was not detected based on relatedness, assignment tests, and haplotype diversity.

Conclusion

This study revealed the importance of landscape connectivity to maintain migration and gene flow between fragmented populations, and to ensure the long-term persistence of species in anthropogenically disturbed landscapes.

Conservation Genetic Assessment of Savannah Elephants (Loxodonta africana) in the Greater Kruger Biosphere, South Africa

Savannah elephant populations have been severely reduced and fragmented throughout its remaining range. In general, however, there is limited information regarding their genetic status, which is essential knowledge for conservation. We investigated patterns of genetic variation in savannah elephants from the Greater Kruger Biosphere, with a focus on those in previously unstudied nature reserves adjacent to Kruger National Park, using dung samples from 294 individuals and 18 microsatellites. The results of genetic structure analyses using several different methods of ordination and Bayesian clustering strongly suggest that elephants throughout the Greater Kruger National Park (GKNP) constitute a single population. No evidence of a recent genetic bottleneck was detected using three moment-based approaches and two coalescent likelihood methods. The apparent absence of a recent genetic bottleneck associated with the known early 1900s demographic bottleneck may result from a combination of rapid post-bottleneck population growth, immigration and long generation time. Point estimates of contemporary effective population size (Ne) for the GKNP were ~ 500-700, that is, at the low end of the range of Ne values that have been proposed for maintaining evolutionary potential and the current ratio of Ne to census population size (Nc) may be quite low (<0.1). This study illustrates the difficulties in assessing the impacts on Ne in populations that have suffered demographic crashes but have recovered rapidly and received gene flow, particularly in species with long generation times in which genetic time lags are longer. This work provides a starting point and baseline information for genetic monitoring of the GKNP elephants.

Invisible barriers: anthropogenic impacts on inter- and intra-specific interactions as drivers of landscape-independent fragmentation

Anthropogenically induced fragmentation constitutes a major threat to biodiversity. Presently, conservation research and actions focus predominantly on fragmentation caused directly by physical transformation of the landscape (e.g. deforestation, agriculture, urbanization, roads, etc.). While there is no doubt that landscape features play a key role in fragmenting populations or enhancing connectivity, fragmentation may also come about by processes other than the transformation of the landscape and which may not be readily visible. Such landscape-independent fragmentation (LIF) usually comes about when anthropogenic disturbance alters the inter- and intra-specific interactions among and within species. LIF and its drivers have received little attention in the scientific literature and in the management of wildlife populations. We discuss three major classes of LIF processes and their relevance for the conservation and management of species and habitats: (i) interspecific dispersal dependency, in which populations of species that rely on other species for transport and propagation become fragmented as the transporting species declines; (ii) interspecific avoidance induction, where species are excluded from habitats and corridors owing to interspecific interactions resulting from anthropogenically induced changes in community structure (e.g. exclusions by increased predation pressure); and (iii) intraspecific behavioural divergence, where populations become segregated owing to anthropogenically induced behavioural differentiation among them.

This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

Toads phenotypically adjust their chemical defences to anthropogenic habitat change

Despite the well-documented effects of human-induced environmental changes on the morphology, physiology, behaviour and life history of wild animals, next to nothing is known about how anthropogenic habitats influence anti-predatory chemical defence, a crucial fitness component of many species. We investigated the amount and composition of defensive toxins in adult common toads (Bufo bufo) captured in natural, agricultural and urban habitats, and in their offspring raised in a common-garden experiment. We found that, compared to toads captured from natural habitats, adults from both types of anthropogenic habitats had larger toxin glands (parotoids) and their toxin secretion contained higher concentrations of bufagenins, the more potent class of bufadienolide toxins. Furthermore, urban toads had lower concentrations of bufotoxins, the compounds with lower toxicity. None of these differences were present in the captive-raised juveniles; instead, toadlets originating from agricultural habitats had smaller parotoids and lower bufotoxin concentrations. These results suggest that toads' chemical defences respond to the challenges of anthropogenic environments via phenotypic plasticity. These responses may constitute non-adaptive consequences of pollution by endocrine-disrupting chemicals as well as adaptive adjustments to the altered predator assemblages of urban and agricultural habitats.

Breeding versus survival: proximate causes of abrupt population decline under environmental change in a desert rodent, the midday gerbil (Meriones meridianus)

Studying abrupt ecological shifts under gradual environmental change caused, in particular, by human activity is important for understanding the fundamental aspects and underlying mechanisms of ecological resilience. One of the rare well-documented examples of an abrupt ecological shift is the delayed step transition of the population of a desert rodent, the midday gerbil (Meriones meridianus), from high-abundance (1994-2002) to low-abundance (2003-2017) regimes. This was in response to landscape transformation from desert to steppe caused by the drastic reduction of livestock in the rangelands of southern Russia after the collapse of the USSR in the early 1990s. In this study, we tested whether demographic parameters were correlated with the observed abrupt downward population shift. We found that reproductive activity (the percentage of breeding females, the number of litters, fecundity and the number of young recruited per female) showed no trend over time and did not differ between periods of high and low abundance. In contrast, the adult sex ratio (SR = males: females) decreased significantly with time and was as much as twice more female-biased for the low-abundance population regime. However, SR was not related to any reproductive parameter, including the percentage of breeding females. We conclude that proximate reasons for an abrupt population decline in M. meridianus are not associated with the changes in breeding patterns or mate limitation caused by the Allee effect but relate to the increased mortality as a result of the desert landscape being fragmented by steppezation. The mortality is expected to be higher for males as the mobile and dispersing sex.

Lifetime inbreeding depression in a leaf beetle

Ongoing habitat loss and fragmentation result in rapid population size reductions, which can increase the levels of inbreeding. Consequently, many species are threatened by inbreeding depression, a loss of individual fitness following the mating of close relatives. Here, we investigated inbreeding effects on fitness-related traits throughout the lifetime of the mustard leaf beetle (Phaedon cochleariae) and mechanisms for the avoidance of inbreeding. Previously, we found that these beetles have family-specific cuticular hydrocarbon profiles, which are likely not used as recognition cue for precopulatory inbreeding avoidance. Thus, we examined whether adult beetles show postcopulatory inbreeding avoidance instead. For this purpose, we determined the larval hatching rate of eggs laid by females mated sequentially with two nonsiblings, two siblings, a nonsibling, and a sibling or vice versa. The beetles suffered from inbreeding depression throughout their entire ontogeny, as evinced by a prolonged larval development, a decreased larval and adult survival and a decreased reproductive output of inbred compared to outbred individuals. The highest larval hatching rates were detected when females were mated with two nonsiblings or first with a sibling and second with a nonsibling. Significantly lower hatching rates were measured in the treatments with a sibling as second male. Thus, the results do not support the existence of postcopulatory inbreeding avoidance in P. cochleariae, but revealed evidence for second male sperm precedence. Consequently, an alternative strategy to avoid inbreeding costs might exist in this beetle, such as a polyandrous mating system, potentially coupled with a specific dispersal behavior.

Animal Social Network Theory Can Help Wildlife Conservation

Many animals preferentially associate with certain other individuals. This social structuring can influence how populations respond to changes to their environment, thus making network analysis a promising technique for understanding, predicting, and potentially manipulating population dynamics. Various network statistics can correlate with individual fitness components and key population-level processes, yet the logical role and formal application of animal social network theory for conservation and management have not been well articulated. We outline how understanding of direct and indirect relationships between animals can be profitably applied by wildlife managers and conservationists. By doing so, we aim to stimulate the development and implementation of practical tools for wildlife conservation and management and to inspire novel behavioral research in this field.

Complex community and evolutionary responses to habitat fragmentation and habitat edges: what can we learn from insect science?

Habitat fragmentation is the primary factor leading to species extinction worldwide and understanding how species respond to habitat edges is critical for understanding the effects of fragmentation on insect diversity in both natural and managed landscapes. Most studies on insect responses to the habitat edge focus on bottom-up changes in resources. Only a few recent studies have examined multi-trophic responses to habitat edges; the results of these studies highlight the problem that we lack a conceptual framework to understand the complex results observed when a single species' response to an edge 'cascades' throughout the food web in ways that are currently not predictable. Recent research from insect systems suggests that habitat edge responses cascade both up and down multi-trophic foodwebs and these altered species interactions may affect evolutionary processes. Future studies that investigate the effects of habitat edges on both ecological and evolutionary dynamics can help to fill these knowledge gaps and we suggest that insects, with short generation times, present an ideal opportunity to do so.

Effects of culling on vigilance behaviour and endogenous stress response of female fallow deer

Context Human activities can induce behavioural and stress responses in wild animals. Information is scarce on the effects of culling on anti-predator behaviour and endogenous stress response of wild ungulates. Aims In a Mediterranean area, we evaluated the effects of culling on vigilance, foraging and endogenous stress response of female fallow deer (Dama dama). Methods Effects of culling were evaluated through behavioural observations and hormone analyses of faecal samples. Key results In an area where culling occurred (C), individuals showed significantly greater vigilance rates and foraged closer to wood than in an area with no culling (NC). In C, 24 h after culling, faecal cortisol concentrations were greater than those recorded in NC, but they decreased significantly to values comparable to (48 h post-shot) and lower than (72 h post-shot) those observed in NC. Conclusions Most likely, culling determined behavioural responses in female fallow deer, but did not trigger long-term physiological effects. Implications Increased anti-predator behaviour may complicate the implementation of long-term culling programs.

Distribution and habitat preference of the broad-toothed rat (Mastacomys fuscus) in the Australian Capital Territory, Australia

The broad-toothed rat (Mastacomys fuscus) is a small to medium-sized rodent found in south-eastern Australia. Recent surveys across the southern portion of its range indicate that the species is in decline, and climate change has been identified as a key threat to the localised persistence of this species. The present study reports on a rapid field survey across 14 high montane and subalpine sites (including moist tussock grassland, sedgelands, heathlands and bogs) in the southern Australian Capital Territory, Australia. M. fuscus scats were recorded along transects, and habitat, vegetation, distance to drainage lines and disturbance due to feral animals were recorded. Relative abundance of M. fuscus was positively related to specific vegetation types (heath, sedge and Poa) and site size. Conversely, relative abundance of M. fuscus was negatively related to disturbance due to feral animals, and distance from creek drainage lines. This study indicates that M. fuscus has specific habitat preferences and threats associated with environmental change and introduced species may threaten populations in the Australian Capital Territory.

Territory configuration moderates the frequency of extra-group mating in superb fairy-wrens

The frequency of extra-pair paternity (EPP) in socially monogamous birds varies substantially between and within species, but ecological drivers of this variation remain poorly understood. Habitat configuration could influence EPP by moderating access to extra-pair mates, because species occupying territories in a clustered 'honeycomb' configuration have a larger pool of potential extra-group mates in their immediate neighbourhood than those living in linearly arranged territories (e.g. along narrow strips of riparian or fragmented habitat). We exploited variation in the spatial arrangement of territories due to anthropogenic modification of habitat of the cooperatively breeding superb fairy-wren Malurus cyaneus to test whether habitat configuration influenced the frequency of EPP. In this species, most paternity is obtained by males outside the social group [extra-group paternity (EGP)]. We found that the frequency of EGP among groups living in linear strips of roadside vegetation (41% of 44 offspring) was lower than it was for groups living in clustered territories within continuous habitat (59% of 70 offspring). Differences in group size and pair relatedness did not explain differences in EGP associated with territory configuration, although the frequency of EGP was negatively correlated with pair relatedness. Our finding suggests that territory configuration can influence rates of EGP and that anthropogenic habitat fragmentation has the potential to limit access to extra-pair mates, affecting mating systems and ultimately fitness.

Species- and sex-specific connectivity effects of habitat fragmentation in a suite of woodland birds

Loss of functional connectivity following habitat loss and fragmentation could drive species declines. A comprehensive understanding of fragmentation effects on functional connectivity of an ecological assemblage requires investigation of multiple species with different mobilities, at different spatial scales, for each sex, and in different landscapes. Based on published data on mobility and ecological responses to fragmentation of 10 woodland-dependent birds, and using simulation studies, we predicted that (1) fragmentation would impede dispersal and gene flow of eight "decliners" (species that disappear from suitable patches when landscape-level tree cover falls below species-specific thresholds), but not of two "tolerant" species (whose occurrence in suitable habitat patches is independent of landscape tree cover); and that fragmentation effects would be stronger (2) in the least mobile species, (3) in the more philopatric sex, and (4) in the more fragmented region. We tested these predictions by evaluating spatially explicit isolation-by-landscape-resistance models of gene flow in fragmented landscapes across a 50 x 170 km study area in central Victoria, Australia, using individual and population genetic distances. To account for sex-biased dispersal and potential scale- and configuration-specific effects, we fitted models specific to sex and geographic zones. As predicted, four of the least mobile decliners showed evidence of reduced genetic connectivity. The responses were strongly sex specific, but in opposite directions in the two most sedentary species. Both tolerant species and (unexpectedly) four of the more mobile decliners showed no reduction in gene flow. This is unlikely to be due to time lags because more mobile species develop genetic signatures of fragmentation faster than do less mobile ones. Weaker genetic effects were observed in the geographic zone with more aggregated vegetation, consistent with gene flow being unimpeded by landscape structure. Our results indicate that for all but the most sedentary species in our system, the movement of the more dispersive sex (females in most cases) maintains overall genetic connectivity across fragmented landscapes in the study area, despite some small-scale effects on the more philopatric sex for some species. Nevertheless, to improve population viability for the less mobile bird species, structural landscape connectivity must be increased.

Environmental quality alters female costs and benefits of evolving under enforced monogamy

Background

Currently many habitats suffer from quality loss due to environmental change. As a consequence, evolutionary trajectories might shift due to environmental effects and potentially increase extinction risk of resident populations. Nevertheless, environmental variation has rarely been incorporated in studies of sexual selection and sexual conflict, although local environments and individuals’ condition undoubtedly influence costs and benefits. Here, we utilise polyandrous and monogamous selection lines of flour beetles, which evolved in presence or absence of sexual selection for 39 generations. We specifically investigated effects of low vs. standard food quality (i.e. stressful vs. benign environments) on reproductive success of cross pairs between beetles from the contrasting female and male selection histories to assess gender effects driving fitness.

Results

We found a clear interaction of food quality, male selection history and female selection history. Monogamous females generally performed more poorly than polyandrous counterparts, but reproductive success was shaped by selection history of their mates and environmental quality. When monogamous females were paired with polyandrous males in the standard benign environment, females seemed to incur costs, possibly due to sexual conflict. In contrast, in the novel stressful environment, monogamous females profited from mating with polyandrous males, indicating benefits of sexual selection outweigh costs.

Conclusions

Our findings suggest that costs and benefits of sexually selected adaptations in both sexes can be profoundly altered by environmental quality. With regard to understanding possible impacts of environmental change, our results further show that the ecology of mating systems and associated selection pressures should be considered in greater detail.

Dynamic social behaviour in a bacterium: pseudomonas aeruginosa partially compensates for siderophore loss to cheats

Cooperation underlies diverse phenomena including the origins of multicellular life, human behaviour in economic markets and the mechanisms by which pathogenic bacteria cause disease. Experiments with microorganisms have advanced our understanding of how, when and why cooperation evolves, but the extent to which microbial cooperation can recapitulate aspects of animal behaviour is debated. For instance, understanding the evolution of behavioural response rules (how should one individual respond to another's decision to cooperate or defect?) is a key part of social evolution theory, but the possible existence of such rules in social microbes has not been explored. In one specific context (biparental care in animals), cooperation is maintained if individuals respond to a partner's defection by increasing their own investment into cooperation, but not so much that this fully compensates for the defector's lack of investment. This is termed 'partial compensation'. Here, I show that partial compensation for the presence of noncooperating 'cheats' is also observed in a microbial social behaviour: the cooperative production of iron-scavenging siderophores by the bacterium Pseudomonas aeruginosa. A period of evolution in the presence of cheats maintains this response, whereas evolution in the absence of cheats leads to a loss of compensatory behaviour. These results demonstrate (i) the remarkable flexibility of bacterial social behaviour, (ii) the potential generality of partial compensation as a social response rule and (iii) the need for mathematical models to explore the evolution of response rules in multi-player social interactions.

The depth of edge influence among insectivorous bats at forest–field interfaces

Species-specific variations in wing morphology and echolocation call characteristics often define which of three structural habitat types (open, cluttered, and edge) different bat species most frequently and efficiently use for foraging. Although edges are recognized as important habitats for commuting and foraging bats, no study to date has examined the depth of edge influence (DEI), the extent of quantitative changes in activity with distance from an edge, for any bat species. We focused our study on five species: northern long-eared bat, Myotis septentrionalis (Trouessart, 1897); hoary bat, Lasiurus cinereus (Beauvois, 1796); little brown bat, Myotis lucifugus (LeConte, 1831); silver-haired bat, Lasionycteris noctivagans (LeConte, 1831); big brown bat, Eptesicus fuscus (Beauvois, 1796). We predicted DEI would vary with species-specific differences in wing morphology and echolocation call characteristics. From June to August in 2010 and 2011, we passively recorded echolocation calls three to four times per month at eight sites in eastern Ontario, Canada. We found that species’ activity was highest at the edge, regardless of wing morphology and echolocation call characteristics. The DEI for all species was approximately 40 m into both forests and fields. Understanding the effects of DEI on bats will enable more effective acoustic monitoring in future studies and may provide crucial information for management decisions.