Ecological Generalists Research Articles

On the role of niche specialization in the geographic distribution of aphid asexual lineages: a case study using the leaf‐curl plum aphid superclones

Asexual lineages often exhibit broad distributions and can thrive in extreme habitats compared to their sexual counterparts. Several hypotheses can be proposed to explain this pattern. Asexual lineages could be versatile genotypes with wide environmental tolerance, enabling their dispersal and persistence across large geographic areas. Alternatively, asexual genotypes could be ecological specialists that thrive in specific environments and outcompete relative colonizing distantly related with similar conditions in the process. Several aphid species feature widespread obligate asexual lineages, commonly known as ‘superclones'. Yet it is often unknown whether these clones are widespread ecological generalists or successful specialists. To explore these hypotheses, we examined climatic niche differentiation among six globally distributed obligate asexual lineages of the cosmopolitan aphid pest, Brachycaudus helichrysi. To ensure that we were investigating the aphid genotype niche and not a by‐product of their association with endosymbionts mediating thermal tolerance, we first verified that clones hosted similar endosymbiont communities. Subsequently, we conducted multivariate analyses on clone occurrence data on a worldwide scale. Our results revealed that, despite their global distribution, B. helichrysi superclones occupy different climatic niches. This study represents the first evidence that aphid superclone distribution can be mediated by distinctive ranges of climatic tolerance.

Analyzing Generalist Plant Species Using Topographic Characteristics of Picea jezoensis (Siebold & Zucc.) Carrière Forests in East Asia: From China (Mt. Changbai) to South Korea

Picea jezoensis (Siebold & Zucc.) Carrière forests are distributed in Korea and China and are crucial for phytogeographical research. Implementing conservation policies encompassing multiple species is necessary to conserve endangered species, particularly monitoring coexisting species and their interactions within an ecological network. Here, we identified plants within P. jezoensis forests in East Asia as generalist species to contribute foundational data for biodiversity conservation. We examined 91 standardized sites through the Braun-Blanquet method, while generalist indices were calculated using Levin’s method. The top 5% of generalists in the P. jezoensis forests were Acer komarovii (0.7409), Betula ermanii (0.7214), Asarum sieboldii (0.7002), Lepisorus ussuriensis (0.6977), Acer pseudosieboldianum (0.6915), Tripterygium regelii (0.6876), Thelypteris phegopteris (0.6771), Dryopteris expansa (0.6745), Sorbus commixta (0.6642), and Rhododendron schlippenbachii (0.6625). Correlation analysis between ecological factors and generalist species revealed that the coverage of Abies spp., Acer spp., and Rhododendron spp. and the species diversity index were influenced by altitude. Convex hull analysis revealed that pteridophytes and broad-leaved plants regenerated through stump sprouts occupy ecological niche spaces, indicating diverse habitats within P. jezoensis forests. This study highlights the importance of the simultaneous monitoring of multiple species to conserve ecosystem health and offers broader implications for ecological understanding.

The American horseshoe crab (Limulus polyphemus) spawns regularly in salt marshes

While considered ecological generalists in most aspects of their life history, horseshoe crabs (Limulus polyphemus) have traditionally been regarded as reproductive habitat specialists, given that spawning is thought to occur primarily on beaches where conditions for embryonic development are considered optimal. Observations of horseshoe crabs spawning in other habitats were deemed isolated and the behavior non‐adaptive. Here, we used spawning and egg surveys to compare the use of beach and salt marsh habitats for spawning by the horseshoe crab in three US states along the Atlantic coast. We found similar spawning and egg densities in both habitats but were more likely to find eggs in marsh habitats, indicating that spawning in marsh habitats is common and geographically widespread. These results suggest that the conservation of salt marshes may be critical for the protection of this species and that management strategies should be revised to incorporate this generalist behavior.

Population status and genetic assessment of mugger (Crocodylus palustris) in a tropical regulated river system in North India

For rewilding the depleted crocodylian populations in India, a targeted ‘one-species one area’ based conservation approach was adopted in the early-1970s. Suitable habitats were identified and designated as protected areas, specifically targeted to recover a particular crocodylian species. A ~ 610 km stretch of Chambal River in the Ganga River Basin was declared as National Chambal Sanctuary to restore the ‘Critically Endangered’ gharial (Gavialis gangeticus), where active management of mugger (Crocodylus palustris) was discouraged. In the present study, we examined the population trends, occupancy, and genetic status of mugger by conducting population monitoring and genetic assessment to understand the status of potentially competitive mugger in the Sanctuary. Our finding suggests that the mugger population has notably increased and colonised the Sanctuary. We observed a moderate level of genetic diversity in the mugger, which was relatively higher compared to the gharial in the Sanctuary. The rapid colonization of ecological generalist mugger raises concerns about potential competition with ecological specialist gharial threatening its long-term sustainability. Considering the coexistence dynamics between the species, it is essential to extend adaptive management strategies for mugger to ensure successful recovery of gharial population in the Sanctuary.

Coexistence mechanism of ecological specialists and generalists based on a network dimension reduction method.

As an ecological strategy for species coexistence, some species adapt to a wide range of habitats, while others specialize in particular environments. Such 'generalists' and 'specialists' achieve normal ecological balance through a complex network of interactions between species. However, the role of these interactions in maintaining the coexistence of generalist and specialist species has not been elucidated within a general theoretical framework. Here, we analyze the ecological mechanism for the coexistence of specialist and generalist species in a class of mutualistic and competitive interaction ecosystems based on the network dimension reduction method. We find that ecological specialists and generalists can be identified based on the number of their respective interactions. We also find, using real-world empirical network simulations, that the removal of ecological generalists can lead to the collapse of local ecosystems, which is rarely observed with the loss of ecological specialists.

Ecological generalism and physiology mediate fish biogeographic ranges under ocean warming.

Climate-driven species redistributions are facilitated by niche modifications that increase a species's chances of establishment in novel communities. It is well understood how range-extending species adjust individual niche traits when entering novel environments, yet whether modification of ecological niche traits collectively alters the pace of range extensions or contractions remains unknown. We quantified habitat niche, abundance, physiological performance and cellular defence/damage of range-extending coral reef fishes and coexisting local temperate fishes along a 2000 km latitudinal gradient. We also assessed their dietary and behavioural niches, and establishment potential, to understand whether ecological generalism facilitates successful range extension of coral reef fishes. The coral reef fish that increased all ecological niches, showed stronger establishment, increased physiological performance and cellular damage, but decreased cellular defence at their cold-range edge, whereas tropical species that showed unmodified ecological niches showed lower establishment. One temperate species showed decreased abundance, habitat niche width and body condition, but increased cellular defence, cellular damage and energy reserves at their warm-trailing range, while other temperate species showed contrasting responses. Therefore, ecological generalists might be more successful than ecological specialists during the initial stages of climate change, with increasing future warming strengthening this pattern by physiologically benefitting tropical generalists but disadvantaging temperate specialists.

Sensory Stimulation as a Means of Sustained Enhancement of Well-Being in Leopard Geckos, Eublepharis macularius (Eublepharidae, Squamata).

Although the private keeping of reptiles has boomed in most western countries since the millennium, studies dealing with the recognition and promotion of welfare in these reptiles seem to represent a blind spot of scientific attention. The vast majority of studies from the field of animal welfare science still concern mammals and birds. The leopard gecko is probably the most common lizard that is kept in domestic terrariums worldwide. Due to its characteristic as an ecological generalist, it is easy to keep and breed, and it is considered a good "starter reptile" for beginners as it "condones" husbandry mistakes, even for extended periods. However, being a mass species is not a second-class classification. They, too, have an equal claim to good well-being as all animals in human care. The aim of the study was to test the hypothesis of whether an increase in stimulus density leads to an increase in activity and behavioural diversity and, thus, an increase in welfare. For this purpose, 18 leopard geckos were fed insects that were ≤1 cm in size, and both the quantity and quality of behaviour was documented and analysed in the pre-intervention, intervention and post-intervention stages. In addition, it was of interest whether behavioural indicators could be identified that indicate a state of positive well-being. The results showed that this type of enrichment led to a quantitative doubling of the activity levels from the baseline (total of 12,519 behavioural elements) to the intervention (total of 25,366 behavioural elements). And even 11 months after the introduction of small insect feeding (post-intervention total of 23,267 behavioural elements), the activity level was still significantly increased. The behavioural diversity, as the absolute number of behavioural categories across all 18 leopard geckos, also increased, although less than the behavioural intensity, between the baseline (5507 behavioural categories) and intervention (6451 behavioural categories) and between the baseline and post-intervention (6079 behavioural categories). The results clearly show that feeding small insects to leopard geckos is a very efficient tool to increase the welfare of leopard geckos. Attractively, this feeding regime can be implemented by any leopard gecko keeper without significant additional cost or time, and therefore, these methods have a potentially high impact.

Formal recognition of host-generalist species of dinoflagellate (Cladocopium, Symbiodiniaceae) mutualistic with Indo-Pacific reef corals.

The existence of widespread species with the capacity to endure diverse, or variable, environments are of importance to ecological and genetic research and conservation. Such "ecological generalists" are more likely to have key adaptations that allow them to better tolerate the physiological challenges of rapid climate change. Reef-building corals are dependent on endosymbiotic dinoflagellates (Family: Symbiodiniaceae) for their survival and growth. While these symbionts are biologically diverse, certain genetic types appear to have broad geographic distributions and are mutualistic with various host species from multiple genera and families in the order Scleractinia, but which must acquire their symbionts through horizontal transmission. Despite the considerable ecological importance of putative host-generalist symbionts, they lack formal species descriptions. In this study, we used molecular, ecological, and morphological evidence to verify the existence of five new host-generalist species in the symbiodiniacean genus Cladocopium. Their geographic distribution and prevalence among host communities corresponds to prevailing environmental conditions at both regional and local scales. The influence that each species has on host physiology may partially explain regional differences in thermal sensitivities among coral communities. The potential increased prevalence of a generalist species that endures environmental instability is a consequential ecological response to warming oceans. Large-scale shifts in symbiont dominance could ensure reef coral persistence and productivity in the near term. Ultimately, these formal designations should advance scientific communication and generate informed research questions on the physiology and ecology of coral-dinoflagellate mutualisms.

Extinction risk patterns in a biodiversity hotspot—The case of Thesium (Santalaceae) in the Greater Cape Floristic Region

AbstractEcologically specialized plants are expected to be at greater risk of extinction than generalists due to climate change. Such risk is greatest in biodiversity hotspots such as the Greater Cape Floristic Region (GCFR), which accommodates both ecological specialists and generalists. Thesium L., a genus with the highest number of species in Santalaceae and the most diverse in Africa, offers an appropriate system for evaluating both the correlates of range extent and specialization and the relative extinction risks associated with both. We hypothesized that range size, ecological specialization, and consequent climatically modulated extinction risks are all phylogenetically structured, such that climate change will precipitate a disproportionate loss of phylogenetic diversity in the GCFR Thesium. Past and future species distribution ranges were predicted using MaxEnt models based on present‐day occurrences and environmental conditions. Of the 101 Thesium species modeled, 70% have had large range sizes during the Last Glacial Maximum (LGM), 50% currently have a large range size, and future conditions are predicted to allow 40% to obtain large range sizes. Between the LGM and the present, 17% of species are thought to have undergone a contraction of available range space in the present time whereas 37% are expected to expand their ranges into the future, while 51% of species will experience range contractions. Of the 65 species currently ranked as Least Concern in the South African Red List, 24% will likely shift into higher extinction risk categories. Interestingly, 8.5% of ecological specialists, although having experienced a range reduction from the LGM to the present, are predicted to persist in the face of future climate change. However, the range extent, ecological specialization, and extinction risk are phylogenetically random and therefore should have a negligible impact on the phylogenetic diversity of the GCFR Thesium.

Dating the origin and spread of specialization on human hosts in Aedes aegypti mosquitoes

The globally invasive mosquito subspecies Aedes aegypti aegypti is an effective vector of human arboviruses, in part because it specializes in biting humans and breeding in human habitats. Recent work suggests that specialization first arose as an adaptation to long, hot dry seasons in the West African Sahel, where Ae. aegypti relies on human-stored water for breeding. Here, we use whole-genome cross-coalescent analysis to date the emergence of human-specialist populationsand thus further probe the climate hypothesis. Importantly, we take advantage of the known migration of specialists out of Africa during the Atlantic Slave Trade to calibrate the coalescent clock and thus obtain a more precise estimate of the older evolutionary event than would otherwise be possible. We find that human-specialist mosquitoes diverged rapidly from ecological generalists approximately 5000 years ago, at the end of the African Humid Period-a time when the Sahara dried and water stored by humans became a uniquely stable, aquatic niche in the Sahel. We also use population genomic analyses to date a previously observed influx of human-specialist alleles into major West African cities. The characteristic length of tracts of human-specialist ancestry present on a generalist genetic background in Kumasi and Ouagadougou suggests the change in behavior occurred during rapid urbanization over the last 20-40 years. Taken together, we show that the timing and ecological context of two previously observed shifts towards human biting in Ae. aegypti differ; climate was likely the original driver, but urbanization has become increasingly important in recent decades.

Insights into the ecological generalist lifestyle of Clonostachys fungi through analysis of their predicted secretomes.

The fungal secretome comprise diverse proteins that are involved in various aspects of fungal lifestyles, including adaptation to ecological niches and environmental interactions. The aim of this study was to investigate the composition and activity of fungal secretomes in mycoparasitic and beneficial fungal-plant interactions. We used six Clonostachys spp. that exhibit saprotrophic, mycotrophic and plant endophytic lifestyles. Genome-wide analyses was performed to investigate the composition, diversity, evolution and gene expression of Clonostachys secretomes in relation to their potential role in mycoparasitic and endophytic lifestyles. Our analyses showed that the predicted secretomes of the analyzed species comprised between 7 and 8% of the respective proteomes. Mining of transcriptome data collected during previous studies showed that 18% of the genes encoding predicted secreted proteins were upregulated during the interactions with the mycohosts Fusarium graminearum and Helminthosporium solani. Functional annotation of the predicted secretomes revealed that the most represented protease family was subclass S8A (11-14% of the total), which include members that are shown to be involved in the response to nematodes and mycohosts. Conversely, the most numerous lipases and carbohydrate-active enzyme (CAZyme) groups appeared to be potentially involved in eliciting defense responses in the plants. For example, analysis of gene family evolution identified nine CAZyme orthogroups evolving for gene gains (p ≤ 0.05), predicted to be involved in hemicellulose degradation, potentially producing plant defense-inducing oligomers. Moreover, 8-10% of the secretomes was composed of cysteine-enriched proteins, including hydrophobins, important for root colonization. Effectors were more numerous, comprising 35-37% of the secretomes, where certain members belonged to seven orthogroups evolving for gene gains and were induced during the C. rosea response to F. graminearum or H. solani. Furthermore, the considered Clonostachys spp. possessed high numbers of proteins containing Common in Fungal Extracellular Membranes (CFEM) modules, known for their role in fungal virulence. Overall, this study improves our understanding of Clonostachys spp. adaptation to diverse ecological niches and establishes a basis for future investigation aiming at sustainable biocontrol of plant diseases.

Defining plant ecological specialists and generalists: Building a framework for identification and classification.

Specialization is a widespread but highly ambiguous and context-dependent ecological concept. This quality makes comparisons across related studies difficult and makes associated terms such as "specialist" and "generalist" scientifically obscure. Here, we present a metric-based framework to quantify specialization in 141 Quercus species using functional traits, biogeography, and species interactions. Rankings of specialization based on five metrics were used to answer questions about how specialization is used colloquially (i.e., individual species assessment by experts) and influenced by phylogenetics (Ancestral Character State Reconstruction, Automatic Shift Detection), biogeography (patterns of clustering by region and with climate), and species threat level (IUCN Red List). Metric-based ranking can be representative of specialization in a consistent and practical manner, correlating with IUCN Red List data, and the mean scores of individual expert assessments. Specialization is shown to be highly correlated with precipitation seasonality and only moderately influenced by evolutionary history. Data-deficient species were more likely to be highly specialized, and higher specialization was positively correlated with greater IUCN threat level. Frameworks for characterizing specialization and generalization can be done using metric ranking and can turn concepts that are often unclear into a definitive system. Metric-based rankings of specialization can also be used to reveal interesting insights about a clade's evolutionary history and geographic distribution when paired with the related phylogenetic and geographic data. Metric-based rankings can be applied to other systems and be a valuable tool for identifying species at risk and in need of conservation.

Landscape genetics reveals contrasting patterns of connectivity in two newt species (Lissotriton montandoni and L. vulgaris).

Ecologically distinct species may respond to landscape changes in different ways. In addition to basic ecological data, the extent of the geographic range has been successfully used as an indicator of species sensitivity to anthropogenic landscapes, with widespread species usually found to be less sensitive compared to range-restricted species. In this study, we investigate connectivity patterns of two closely related but ecologically distinct newt species - the range-restricted, Lissotriton montandoni and the widespread, L. vulgaris - using genomic data, a highly replicated setting (six geographic regions per species), and tools from landscape genetics. Our results show the importance of forest for connectivity in both species, but at the same time suggest differential use of forested habitat, with L. montandoni and L. vulgaris showing the highest connectivity at forest-core and forest-edges, respectively. Anthropogenic landscapes (i.e., higher crop- or urban-cover) increased resistance in both species, but the effect was one to three orders of magnitude stronger in L. montandoni than in L. vulgaris. This result is consistent with a view of L. vulgaris as an ecological generalist. Even so, currently, the negative impact of anthropogenic landscapes is mainly seen in connectivity among L. vulgaris populations, which show significantly stronger isolation and lower effective sizes relative to L. montandoni. Overall, this study emphasizes how habitat destruction is compromising genetic connectivity not only in endemic, range-restricted species of conservation concern but also in widespread generalist species, despite their comparatively lower sensitivity to anthropogenic landscape changes.

Agroecosystem Ecology of Northern Deermice (Peromyscus maniculatus bairdii) and White-Footed Deermice (P. leucopus noveboracensis) in the Inner Bluegrass of Kentucky

Peromyscus leucopus (White-Footed Deermouse) and Peromyscus maniculatus (North American Deermouse) are 2 widespread rodent species in North America, with North American Deermice more ecologically diverse and widely distributed than White-footed Deermice. Commonly, White-Footed Deermice are ecological generalists, and North American Deermice are ecological specialists. In the Inner Bluegrass Region of Kentucky, these 2 species are sympatric in agroecosystems habitats, including the University of Kentucky North Farm. This farm was the most trapped location in central Kentucky from 1950 to 1968, with results indicating the White-Footed Deermoouse was the more common of these species. Trapping from 1995 to 2015 found that North American Deermice were caught rarely. Our study examined agroecosystems habitats at the UK North Farm, including all perennial and annual habitats, to determine the relative abundance and habitat use by both these species. In our study, North American Deermice was the most commonly captured species; it was trapped rarely in perennial habitats but much more frequently in annual crops. Perennial clover fields and Medicago sativa (Alfalfa) were the 2 exceptions; however, these are short crops with exposed soil between rows. Essentially, North American Deermice were observed in the agricultural equivalent of early successional habitat. In contrast, White-Footed Deermice were captured in both perennial and annual habitats, but more commonly in perennial habitats, the exception being annual Salvia hispanica (Chia) fields where dense, green plants produced a thick canopy. Overall, the best predictor of habitat for North American Deermice was bare, exposed soil, whereas the best predictor for White-Footed Deermice was dense growth and overhead cover.

A multifaceted ecological assessment reveals the invasion of the freshwater red macroalga Montagnia macrospora (Batrachospermales, Rhodophyta) in Taiwan.

Invasive freshwater macroalgae are rarely described. Montagnia macrospora is a freshwater red alga introduced from South America to East Asia via the global aquarium trade. The earliest occurrence record of this alga in Taiwan is dated 2005. To determine whether M. macrospora has become invasive in Taiwan and to understand the traits that facilitated its invasion, we took a multifaceted approach that combines examination of ecological background and population genetic analysis. Our island‐wide survey showed that M. macrospora is widespread in the field across Taiwan, where the climate greatly differs from that of South America, and can self‐sustain for nearly a decade. Our population genetic analysis revealed a lack of genetic diversity of M. macrospora in Taiwan, consistent with the hypothesis that the alga expanded through asexual reproduction. Moreover, during our long‐term ecological assessments and field surveys, we observed that M. macrospora is an ecological generalist that can survive in a wide range of temperature, pH, illumination, and nutrient enrichment. Taken together, our data suggest that M. macrospora has successfully invaded the freshwater ecosystems of Taiwan, likely due to its ability to disperse asexually and to grow under broad environmental conditions. We hope that our study brings attention to invasive freshwater algae, which have been overlooked in conservation planning and management.

Different Physiology in the Jellyfish Cassiopea xamachana and C. frondosa in Florida Bay

The jellyfish Cassiopea xamachana and C. frondosa co-occur within some habitats in the Florida Keys, but the frequency with which this occurs is low. It is hypothesized that the symbiosis with different dinoflagellates in the Symbiodiniaceae is the reason: the medusae of C. xamachana contain heat-resistant Symbiodinium microadriaticum (ITS-type A1), whereas C. frondosa has heat-sensitive Breviolum sp. (ITS-type B19). Cohabitation occurs at depths of about 3–4 m in Florida Bay, where the water is on average 0.36 °C cooler, or up to 1.1 °C cooler per day. C. frondosa tends not to be found in the warmer and shallower (<2 m) depths of Florida Bay. While the density of symbionts is about equal in the small jellyfish of the two species, large C. frondosa medusae have a greater density of symbionts and appear darker in color compared to large C. xamachana. However, the number of symbionts per amebocyte are about the same, which implies that the large C. frondosa has more amebocytes than the large C. xamachana. The photosynthetic rate is similar in small medusae, but a greater reduction in photosynthesis is observed in the larger medusae of C. xamachana compared to those of C. frondosa. Medusae of C. xamachana have greater pulse rates than medusae of C. frondosa, suggestive of a greater metabolic demand. The differences in life history traits of the two species were also investigated to understand the factors that contribute to observed differences in habitat selection. The larvae of C. xamachana require lower concentrations of inducer to settle/metamorphose, and they readily settle on mangrove leaves, submerged rock, and sand compared to the larvae of C. frondosa. The asexual buds of C. xamachana are of a uniform and similar shape as compared to the variably sized and shaped buds of C. frondosa. The larger polyps of C. frondosa can have more than one attachment site compared to the single holdfast of C. xamachana. This appears to be an example of niche diversification that is likely influenced by the symbiont, with the ecological generalist and heat-resistant S. microadriaticum thriving in C. xamachana in a wider range of habitats as compared to the heat-sensitive symbiont Breviolum sp., which is only found in C. frondosa in the cooler and deeper waters.

The genetic drivers for the successful invasive potential of a generalist bird, the House crow

What kind of genetic structure helps the rapid range expansion of the invasive species is fundamental to understand spread of invasion. The House crow (Corvus splendens), an ecological generalist, having a large native and introduced distribution range, is a good study model to investigate the genetic structure and adaptations underpinning the evolutionary potential for successful biological invasion. Thirteen mainland and one island native population from the Indian subcontinent were studied using four nuclear introns and mitochondrial genome to determine the phylogeographic structure and demographic history. A large, panmictic long-term expanding native population dating from the last glacial period (~ 30,000 ya) was inferred leading to great genetic diversity across the whole native range. The thirteen mitochondrial encoded proteins, directly involved in the energy supplying pathway, could underlie metabolic adaptations during range expansion under diverse climate conditions. Therefore, to investigate the molecular selection on these genes in native and introduced ranges, five previously studied introduced populations from Southeast Asia and Africa were included. The native populations originating from hot arid and humid tropical areas exhibited the signatures of positive selection on four codons located in three genes (ND5, Cytb and COX2), suggesting these may have evolved under environmental stresses in those regions. Our findings demonstrated the native range population as the reservoir of the species’ genetic diversity, mitogenomic patterns of the introduced populations related to native range of species and no varaints could be associated with climate in introduced range. Thus,inferred that the pre-adapted standing genetic variations evolved during dispersion over the native range are the predominant source of the high evolutionary potential and contribute to the successful invasion history. These findings will help to predict the future introduced range of the House crow.

Linking cognition to ecology in wild sympatric mouse lemur species.

Cognitive abilities covary with both social and ecological factors across animal taxa. Ecological generalists have been attributed with enhanced cognitive abilities, but which specific ecological factors may have shaped the evolution of which specific cognitive abilities remains poorly known. To explore these links, we applied a cognitive test battery (two personality, ten cognitive tests; n = 1104 tests) to wild individuals of two sympatric mouse lemur species (n = 120 Microcebus murinus, n = 34 M. berthae) varying in ecological adaptations but sharing key features of their social systems. The habitat and dietary generalist grey mouse lemurs were more innovative and exhibited better spatial learning abilities; a cognitive advantage in responding adaptively to dynamic environmental conditions. The more specialized Madame Berthe's mouse lemurs were faster in learning associative reward contingencies, providing relative advantages in stable environmental conditions. Hence, our study revealed key cognitive correlates of ecological adaptations and indicates potential cognitive constraints of specialists that may help explain why they face a greater extinction risk in the context of current environmental changes.

Climate change can disrupt ecological interactions in mysterious ways: Using ecological generalists to forecast community-wide effects

Ecological interactions are the backbone of biodiversity. Like individual species, interactions are threatened by drivers of biodiversity loss, among which climate change operates at a broader scale and can exacerbate the effects of land-use change, overharvesting, and invasive species. As temperature increases, we expect that some species may alter their distribution towards more amenable conditions. However, a warmer and drier climate may impose local effects on plants and animals, disrupting their interactions before noticeable changes in distribution are observed. We used a mutualistic trio from the temperate forests of South America to theoretically illustrate how climate change can disrupt ecological interactions, based on our current knowledge on this system. This study system comprises three generalist species with intersecting roles: a keystone mistletoe, a pollinator hummingbird, and a frugivorous marsupial that disperses the seeds of many species. On the one hand, drought causes water stress, increasing mortality of both mistletoe and host plants, and reducing the production of flowers and fruits. These resource shortages negatively impact animal's foraging opportunities, depleting energy reserves and compromising reproduction and survival. Finally, warmer temperatures disrupt hibernation cycles in the seed-dispersing marsupial. The combined result of these intersecting stressors depresses interaction rates and may trigger an extinction vortex if fail to adapt, with deep community-wide implications. Through negatively affecting generalist mutualists which provide resilience and stability to interaction networks, local-scale climate impacts may precipitate community-wide extinction cascades. We urge future studies to assess climate change effects on interaction networks rather than on singular species or pairwise partnerships.

Warming increases activity in the common tropical frog Eleutherodactylus coqui

Tropical ecosystems are expected to experience climate warming, with predicted increases in drying and heat extremes in the coming years. Understanding how these changes will affect terrestrial vertebrates such as amphibians is limited. The Tropical Responses to Altered Climate Experiment in the Luquillo Experimental Forest in northeastern Puerto Rico allows us to study how the tropical forest responds to warming within a replicated plot design. From September 2018 to August 2019, we used mark-recapture sampling to investigate how the spatial population ecology of the common coqui frog (Eleutherodactylus coqui) is impacted by experimentally increasing surface temperatures by 4 °C above ambient. We compared estimates of baseline detection, space use, and the density of frogs in control and warmed plots. Coqui space use and population density did not differ between control and warmed plots. However, coqui detection probabilities were higher in warmed plots, suggesting an increased level of activity relative to individuals in the control (unwarmed) plots. Frog detection increased in all plots with increased precipitation. Our results suggest that, at least in the short-term, the density of an ecological generalist frog like E. coqui does not change as a response to increased surface temperatures. However, short-term responses to warming such as changes in behavior may lead to changes in population dynamics in the long-term. Our research highlights the need to consider mutiple repsonses in order to understand the effects of climate warming on tropical vertebrates.