Hypoxia has profound and diverse effects on aerobic organisms, disrupting oxidative phosphorylation and activating several protective pathways. Predictions have been made that exposure to mild intermittent hypoxia may be protective against more severe exposure and may extend lifespan. Both effects are likely to depend on prior selection on phenotypic and transcriptional plasticity in response to hypoxia, and may therefore show signs of local adaptation. Here we report the lifespan effects of chronic, mild, intermittent hypoxia (CMIH) and short-term survival in acute severe hypoxia (ASH) in four clones of Daphnia magna originating from either permanent or intermittent habitats, the latter regularly drying up with frequent hypoxic conditions. We show that CMIH extended the lifespan in the two clones originating from intermittent habitats but had the opposite effect in the two clones from permanent habitats, which also showed lower tolerance to ASH. Exposure to CMIH did not protect against ASH; to the contrary, Daphnia from the CMIH treatment had lower ASH tolerance than normoxic controls. Few transcripts changed their abundance in response to the CMIH treatment in any of the clones. After 12 hours of ASH treatment, the transcriptional response was more pronounced, with numerous protein-coding genes with functionality in mitochondrial and respiratory metabolism, oxygen transport, and, unexpectedly, gluconeogenesis showing up-regulation. While clones from intermittent habitats showed somewhat stronger differential expression in response to ASH than those from permanent habitats, there were no significant hypoxia-by-habitat of origin or CMIH-by-ASH interactions. GO enrichment analysis revealed a possible hypoxia tolerance role by accelerating the molting cycle and regulating neuron survival through up-regulation of cuticular proteins and neurotrophins, respectively.
Habitat divergence among close relatives is a common theme in ecology. While recent studies have frequently found that the abundance and diversity of plant species are regulated by soil microbes, little is known whether soil microbes can also affect the habitat distributions of plants. To fill in this knowledge gap, we investigated whether interactions with soil microbes restrict habitat distributions of closely related oaks (Quercus spp.) in eastern North America. We performed a soil inoculum experiment using two pairs of sister species that show habitat divergence: Quercus alba (local species) vs. Q. michauxii (foreign), and Q. shumardii (local) vs. Q. acerifolia (foreign). To test whether host-specific soil microbes are responsible for habitat restriction, we investigated the impact of local sister live soil (containing soil microbes associated with local sister species) on the survival and growth of local and foreign species. Secondly, to test whether habitat-specific soil microbes are responsible for habitat restriction, we also examined the effect of local habitat live soil (containing soil microbes within local sister’s habitats, but not directly associated with roots of local sister species) on the seedlings of local and foreign species. We found that local sister live soil decreased the survival and biomass of foreign species’ seedlings while increased those of local species, which supports the roles of host-specific microbes in mediating habitat exclusion. In contrast, local habitat live soil did not differentially affect the survival or biomass of the local vs. foreign sister species, providing no support for the roles of habitat-specific microbes. Our study indicates that soil microbes associated with one sister species can suppress the recruitment of the other host species, contributing to habitat partitioning of the closely related oaks. Our findings emphasize that considering the complex interactions with soil microbes is essential for understanding habitat distributions of closely related plants.
Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently investigated species. Eleginops maclovinus is a protandrous hermaphrodite species with economic importance for local communities that is currently managed as a single genetic unit. In this study, we sampled five locations distributed across a salinity cline from Northern Patagonia to investigate the genetic population structure of E. maclovinus. We use Restriction-site Associated DNA (RAD) sequencing and outlier tests to obtain neutral and adaptive loci, using FST and GEA approaches. We identified a spatial pattern of structuration with gene flow and spatial selection by environmental association. Neutral and adaptive loci showed two and three genetic groups, respectively. The effective population sizes estimated ranged from 572 (Chepu) to 14,454 (Chaitén) and were influenced more by locality than salinity cline. We found loci putatively associated with salinity suggesting that salinity may act as a selective driver in E. maclovinus populations. These results suggest a complex interaction between genetic drift, geneflow, and natural selection in this area. Our findings suggest several units in this area, and the information should be integrated into the management of this species. We discuss the significance of these results for fishery management and suggest future directions to improve our understanding of how E. maclovinus is adapted to the dynamic waters of Northern Patagonia.
Thousands of plant species produce both extrafloral nectaries (EFNs) on their leaves and nutrient-rich appendages on their diaspores (elaiosomes). Although their individual ecology is well-known, any possible functional link between them has been ignored. Here, we recognized their co-presence in the shrub, Adenanthos cygnorum (Proteaceae), and studied their function and interaction. We observed that ants frequently visit both structures, seeds are attractive to vertebrate granivores but are released into a leafy cup from where they are harvested by ants and taken to their nests, from which seeds, lacking elaiosomes, germinate after fire. We showed that juvenile plants do not produce EFNs and are not visited by ants. We conclude that EFNs are not just an indirect adaptation to minimize herbivory via aggressive ants (or parasitoid wasps) but specifically enhance reproductive success by inducing ants to visit the plant throughout the year, promoting discovery of the seasonally available, elaiosome-bearing seeds on the plant and transporting them to their nests, so avoiding the risk of granivory should seeds fall to the ground.
The buffy-tufted-ear marmoset (Callithrix aurita) is a small primate endemic to the Brazilian Atlantic Forest biome, and one of the 25 most endangered primates in the world, due to fragmentation, loss of habitat, and invasion by allochthonous Callithrix species. Using occurrence data for C. aurita from published data papers, we employed model selection and cumulative AICc weight (w+) to evaluate whether fragment size, distance to fragments with allochthonous species, altitude, connectivity, and surrounding matrices influence the occurrence of C. aurita within its distributional range. Distance to fragments with C. jacchus (w+ = 0.94) and non-vegetated areas (w+ = 0.59) correlated negatively with C. aurita occurrence. Conversely, the percentage of agriculture and pasture mosaic (w+ = 0.61) and the percentage of savanna formation (w+ = 0.59) in the surrounding matrix correlated positively with C. aurita occurrence. The findings indicate that C. aurita is isolated in forest fragments surrounded by potentially inhospitable matrices, along with the proximity of a more generalist and invasive species, thereby increasing the possibility of introgressive hybridization. The findings also highlighted the importance of landscape factors and allochthonous congeneric species for C. aurita conservation, besides indicating urgency for allochthonous species management. Finally, the approach used here can be applied to improve conservation studies of other endangered species, such as C. flaviceps, which is also endemic to the Brazilian Atlantic Forest and faces the same challenges.
How first-time animal migrants find specific destinations remains an intriguing ecological question. Migratory marine species use geomagnetic map cues acquired as juveniles to aide long-distance migration, but less is known for long-distance migrants in other taxa. We test the hypothesis that naïve Eastern North American fall migratory monarch butterflies (Danaus plexippus), a species that possesses a magnetic sense, locate their overwintering sites in Central Mexico using inherited geomagnetic map cues. We examined whether overwintering locations and the abundance of monarchs changed with the natural shift of Earth’s magnetic field from 2004 to 2018. We found that migratory monarchs continued to overwinter at established sites in similar abundance despite significant shifts in the geomagnetic field, which is inconsistent with monarchs using fine scale geomagnetic map cues to find overwintering sites. It is more likely that monarchs use geomagnetic cues to assess migratory direction rather than location and use other cues to locate overwintering sites.
Determining what factors influence the distribution and abundance of wildlife populations is crucial for implementing effective conservation and management actions. Yet, for species with dynamic seasonal, sex-, and age-specific spatial ecology, like the diamondback terrapin (Malaclemys terrapin; DBT), doing so can be challenging. Moreover, environmental factors that influence the distribution and abundance of DBT in their northernmost range have not been quantitatively characterized. We investigated proximity to nesting habitat as one potential driver of spatiotemporal variation in abundance in a three-step analytical approach. First, we used a scale selection Resource Selection Function (RSF) approach based on NLCD landcover data to identify the scale at which DBT are selecting for (or avoiding) landcover types to nest. Next, we used RSF to predict areas of suitable nesting habitat and created an index of nest suitability (NSI). Finally, analyzing visual count data using a generalized linear mixed model (GLMM), we investigate spatiotemporal drivers of relative abundance, with a specific focus on whether similar factors affect offshore abundance and onshore nest site selection. We found the scale of selection for developed and saltmarsh land use classes to be 500 m and 525 m and coniferous, beach and open water land use classes to be 100 m. Selection was positive for nesting areas proximal to saltmarsh and beach habitat and negative for developed, coniferous and open water. Expected relative abundance was best explained by the interaction between NSI and day of season, where expected relative abundance was greater within high NSI areas during the nesting season (2.30 individuals, CI: 1.29 – 4.10) compared to areas of low NSI (1.99 individuals, CI: 1.27 – 3.13). Our results provide evidence that inferred spatial patterns of suitable nesting habitat explain spatiotemporal patterns of terrapin movement and abundance.
1. Omnivores utilise dietary sources which differ in nutrients, hence dietary restrictions due to environmental change or habitat alteration should cause nutrient limitations; and thus, deterioration of body condition if omnivory is obligate. 2. We investigated how the body condition of the Village weaver Ploceus cucullatus (weavers), which forages predominantly on grains, responds to insects and fruits deprivation. 3. Forty wild-caught weavers held in aviaries were fed a combination of grains and fruits, or grains and insects ad libitum for eight weeks. We confirmed diet preference by recording the number of foragers on each diet option per minute for one hour and the amount of food left-over after 3 hours of foraging. Fortnightly, we assessed indices of body condition including body mass, pectoral muscle, and fat scores, Packed Cell Volume (PCV) and Haemoglobin Concentration (HBC). We modelled the number of foragers, food left-over and body condition as functions of diet, while accounting for time (weeks) and sex effects. 4. We confirmed grains as the preferred diet and found that males ate more fruits and insects than females. Weavers fed on grains and fruits lost body and pectoral muscle mass and accumulated less fat than those fed on grains and insects. This effect was sex-dependent: females deprived of insects lost more pectoral muscle mass than males of the same group and males but not females, deprived of fruits accumulated more fat reserve than those deprived of insects. PCV and HBC did not differ between diets but increased over the eight weeks. 5. Weavers are likely obligate rather than facultative omnivores, with insects as being a more nutritive supplement than fruits. We conclude that nutrient limitation arising from environmental change or habitat alteration can impair body condition and affect physiological response to environmental seasonality in other obligate omnivores like the weavers.
The domestic cat, Felis catus, is one of the most popular and widespread domestic animals. Because domestic cats can reach high population densities and retain at least some tendency to hunt, their overall impact on wildlife can be severe. Domestic cats have highly variable predation rates depending on the availability of prey in their environment, their owners' practices, and individual cat characteristics. Among these characteristics, cat personality has recently been hypothesized to be an important factor contributing to variations in the hunting activity of cats. In this study, we used surveys of 2,508 cat owners living in France to collect information about cat personalities using the Feline Five personality model and about the frequency with which the cats bring home prey. For both birds and rodents, cats with high levels of extraversion or low levels of neuroticism had significantly higher frequencies of prey return. Owners whose cats had low levels of agreeableness or high levels dominance reported a significantly lower frequency of bird return. Personality differences therefore seem to contribute to the high variability in predation rates between domestic cats. We also found that the owner-reported prey return frequencies were significantly higher for cats spending more time outdoors, for non-pedigree cats, and for owners living in rural or suburban areas as opposed to urban areas. By contrast, we did not detect an effect of cat sex or age on their reported prey return rates.
1. Recent empirical studies have quantified correlation between survival and recovery by estimating these parameters as correlated random effects with Bayesian multivariate mixed effects models fit to tag-recovery data. In these applications, increasingly negative correlation between survival and recovery indicates increasingly additive harvest mortality. The power of mixed effects models to detect non-zero correlations has rarely been evaluated and these few studies have not focused on a common data type in the form of tag recoveries. 2. We assessed the power of multivariate mixed effects models to estimate negative correlation between annual survival and recovery. Using three priors for multivariate normal distributions, we fit mixed effects models to a mallard (Anas platyrhychos) tag-recovery dataset and to simulated data with sample sizes corresponding to different levels of monitoring intensity. We also demonstrate a method of calculating effective sample size for capture-recapture data. 3) Different priors lead to different inference about additive harvest when we fit our models to the mallard data. Our power analysis of simulated data indicated most prior distribution and sample size combinations resulted in correlation estimates with substantial bias and imprecision. Many correlation estimates spanned the available parameter space (–1,1) and were biased towards zero. Only one prior combined with our most intensive monitoring scenario allowed our models to consistently recover negative correlation without bias. Underestimating the magnitude of correlation coincided with overestimating the variability of annual survival, but not annual recovery. 4) The inadequacy of prior distributions and sample size combinations typically assumed adequate for robust inference represents a concern in the application of Bayesian mixed effects models for the purpose of informing harvest management. Our analysis approach provides a means for examining prior influence and sample size on mixed-effects models fit to capture-recapture data while emphasizing transferability of results between empirical and simulation studies.
• The carnivorous pitcher plant Sarracenia purpurea is native to North America, but has been introduced into Europe, where it is now widespread. We have little understanding of how this species functions in its non-native range. Such understanding will provide insight into S. purpurea ecology and support its use as a model system for investigating food webs. We measured pitcher morphology and prey capture by S. purpurea in Britain and Ireland. • Pitchers were removed from different plants at each of six bogs covering the species rage in the UK and Ireland (n = 10 pitchers per site). For each pitcher we counted and identified every prey item and took measurements of morphology. We also compiled prey capture data for existing studies in Europe and North America. • Prey capture characteristics varied between sites in the UK and Ireland. The amount of prey captured varied 2-fold between sites and was partially explained by differences in pitcher size; larger pitchers caught more prey. The primary prey was Formicidae, Diptera and Coleoptera. At the rank of order, prey composition varied between bogs, some contained mainly Formicidae, some mainly Diptera and some a mix. Plants were more specialised in prey capture at some bogs compared to others. There was no overall difference in prey capture (composition or degree of specialism) at the rank of order between plants in Europe compared to those in North America. At the rank of species, prey capture varied between populations even within the same order. • This study demonstrates a large amount of variability between sites in prey capture characteristics. This may reflect different site characteristics and/or plant strategies, will likely impact plant function, and may impact on the inquiline community. In terms of prey capture at the rank of order S. purpurea functions identically in its non-native range. This supports its use as a natural experiment for understanding food webs
Aim: Selection within natural communities has mainly been studied along large abiotic gradient, while the selection of individuals within population should occur locally under the play of biotic filter. To better seize the role of the latter, we postulated that the hierarchal nature of environmental selection and the multiple dimension of species trait space needed to be accounted for. Methods: We replicated a natural species richness gradient (from 2 to 16 species) within four contrasted wetlands (bog, fen, meadow, marsh), sampling functional traits from random individuals in communities. Developing a hierarchical distributional modelling, we analyzed the variation of the mean and dispersion of functional trait space at the ecosystem, community and species levels. Key results: We found that the abiotic differences between wetlands, which shaped a plant productivity gradient, selected species in regards with their leaf nutrient conservation / acquisition strategy. Within ecosystems, plant species richness was a strong driver of trait variation among both communities and species. Among communities, it shaped the selection of individuals according to their space occupation and leaf adaptations to light conditions. Demographically, some species used intraspecific trait variation to maintain equally dense populations, while others used it to become dominant in favorable conditions. Main Conclusions: Within ecosystems, variation in biotic conditions selects individuals along functional dimensions that are independent to the ones selected across ecosystems. Because intraspecific variations of light-related traits are related to demographic responses, it offers a way to link the study of species richness and eco-evolutionary dynamics.
Senescence seems to be universal in living organisms and plays a major role in life‐history strategies. Phenotypic senescence, the decline of body condition and/or performance with age, is a largely understudied component of senescence in natural insect populations, although it would be important to understand how and why insects age under natural conditions. We aimed (i) to investigate how body mass and thorax width change with age in a natural population of the univoltine Clouded Apollo butterfly (Parnassius mnemosyne, Lepidoptera: Papilionidae) and (ii) to assess the relationship of this change with sex and wing length. We studied a population between 2014 and 2020 using mark‐recapture during the whole flight period each year. Repeated measurements of body mass and thorax width and single measurements of wing length were performed on marked individuals. We analyzed body mass and thorax width change with age (days since marking), wing length, and the date of the first capture. Both body mass and thorax width declined nonlinearly with age. Individuals appearing earlier in the flight period had significantly higher initial body mass and thorax width and their body mass declined faster than later ones. Initial body sizes of females were higher, but males' body sizes decreased slower. Initial thorax width showed higher annual variation than body mass. To our best knowledge, this is the first study that revealed phenotypic senescence in a natural butterfly population, using in vivo measurements. We found sexual differences in the rate of phenotypic senescence. Despite the annual variation of initial body sizes, the rate of senescence did not vary considerably across the years. Phenotypic senescence is a largely understudied component of senescence in natural insect populations. In a wild Clouded Apollo population investigated by us, both body mass and thorax width declined nonlinearly with age. Individuals appearing earlier in the flight period had significantly higher initial body mass and thorax width, and their body mass declined faster than later ones. Initial body sizes of females were higher, but males' body sizes decreased slower. Initial thorax width showed higher annual variation than body mass.
Although the field of urban evolutionary ecology is in its infancy, much progress has been made in identifying adaptations that arise as a result of selective pressures within these unique environments. However, as studies within urban environments have rapidly increased, researchers have recognized there are challenges and opportunities in characterizing urban adaptation. Some of these challenges are novel as a consequence of increased direct and indirect human influence, which compounds long-recognized issues with research on adaptive evolution more generally. In this perspective, we discuss several common research challenges to urban adaptation related to: (1) methodological approaches, (2) trait-environment relationships and the natural history of organisms, (3) agents and targets of selection, and (4) habitat heterogeneity. Ignoring these challenges may lead to misconceptions and further impede our ability to draw conclusions regarding evolutionary and ecological processes in urban environments. Our goal is to first shed light on the conceptual challenges of conducting urban adaptation research to help avoid propagation of these misconceptions. We further summarize potential strategies to move forward productively to construct a more comprehensive picture of urban adaptation, and discuss how urban environments also offer unique opportunities and applications for adaptation research.
Understanding population change across long time scales and at fine spatiotemporal resolutions is important for confronting a broad suite of conservation challenges. However, this task is hampered by a lack of quality long-term census data for multiple species collected across large geographic regions. Here, we used century-long (1919-2018) data from the Audubon Christmas Bird Count (CBC) survey to assess population changes in over 300 avian species in North America and evaluate their temporal non-stationarity. To estimate population sizes across the entire century, we employed a Bayesian hierarchical model that accounts for species detection probabilities, variable sampling effort, and missing data. We evaluated population trends using generalized additive models (GAMs) and assessed temporal non-stationarity in the rate of population change by extracting the first derivatives from the fitted GAM functions. We then summarized the population dynamics across species, space, and time using a non-parametric clustering algorithm that categorized individual population trends into four distinct trend clusters. We found that species varied widely in their population trajectories, with over 90% of species showing a considerable degree of spatial and/or temporal non-stationarity, and many showing strong shifts in the direction and magnitude of population trends throughout the past century. Species were roughly equally distributed across the four clusters of population trajectories, though grassland, forest, and desert specialists more commonly showed declining trends. Interestingly, for many species, region-wide population trends often differed from those observed at individual sites, suggesting that conservation decisions need to be tailored to fine spatial scales. Together, our results highlight the importance of considering spatial and temporal non-stationarity when assessing long-term population changes. More generally, we demonstrate the promise of novel statistical techniques for improving the utility and extending the temporal scope of existing citizen science datasets.
In the French Mediterranean plain, the northern extreme of its native range, the Iberian grey shrike, Lanius meridionalis, predominantly feeds on arthropods. Its type of loral plumage plays a key role in protecting its eyes while transporting large prey. The aims is to understand the role played by feathers in protecting the animal from various types of defensive prey. We combine an inspection of large insect prey types found on larders with a review of bird specimens found in museum collections to examine the morphometric characteristics of rictal feathers and culmen. In addition, precision photographs are used to observe the posture of the plumage in natura. We could identify four categories of protective feathers: clustered bristles, semi-bristles, semi-plumes distributed in the loral area, and semi-plumes above the eyes. Our results suggest that the Iberian grey shrike has a complex structure of loral feathers, specific to its foraging activity and prey types. In France, local species have longer beaks than their Spanish counterparts which suggests a more insect-based diet.
The existence of hypopigmentation such as leucism is the result of inbreeding in isolated populations of wildlife and it is associated with environmental stressors. This anomaly may reduce survival rates. Leucism has been record in wildlife, but overall, it is considered very rare. There have been few records of mantled howler monkeys with leucism in Mexico and Costa Rica, but whole-body leucism in howler monkeys from South America was unknown. In this article, we report for the first-time documented cases of whole-body leucism in young individuals of mantled howler monkeys Alouatta palliata in an isolated remanent of tropical dry forest in southwestern Ecuador known as Cerro Blanco Protective Forest. In total, we found two individuals: a juvenile female and a juvenile male in October 2021. We also include a short report about the observation of two seedlings of Dichapetalum (Dichapetalaceae) showing albinism. The report of howler monkeys with whole-body leucism may be caused by the interaction of two processes: inbreeding because of isolated populations and air pollution with sulphur. Thus, immediate management strategies must be considered to significantly increase connectivity with other populations of howler monkeys and reduce air pollution in Guayaquil. Our findings also reveal that hypopigmentation is becoming more frequent in howler monkey´s population along its distributional range. Therefore, we encourage the community to consider a regional management strategy.
Telomeres, the terminal repetitive DNA sequences at the ends of linear chromosomes, have strong associations with longevity in some major taxa. Longevity has been linked to rate of decline in telomere length in birds and mammals, and absolute telomere length seems to be associated with body mass in mammals. Using a phylogenetic comparative method and 30 species of birds, we examined longevity (reflected by maximum lifespan), absolute telomere length, the rate of change in telomere length (TROC), and body mass (often strongly associated with longevity) to ascertain their degree of association. We divided lifespan into two life-history components, one reflected by body size (measured as body mass), and a component that was statistically independent of body mass. While both lifespan and body mass were strongly associated with a family tree of the species (viz., the phylogeny of the species), telomere measures were not. Telomere length was not significantly associated with longevity or body mass, or our measure of mass-independent lifespan. TROC, however, was strongly associated with mass-independent lifespan, but to a lesser degree with body mass. Our results supported an association of TROC and longevity, in particular longevity that was independent of body size and part of the pace-of-life syndrome of life histories.