It is hot and cold here: the role of thermotolerance in the ability of spiders to colonize tree plantations in the southern Atlantic Forest.

Worldwide, with the decline of natural habitats, species with reduced niche breadth (specialists) are at greater risk of extinction as they cannot colonise or persist in disturbed habitat types. However, the role of thermal tolerance as a critical trait in understanding changes in species diversity in disturbed habitats, e.g., due to forest replacement by tree plantations, is still understudied. To examine the role of thermal tolerance on the responses of specialist and generalist species to habitat disturbances, we measured and compared local temperature throughout the year and thermotolerance traits [upper (CTmax) and lower (CTmin) thermal limits] of the most abundant species of spiders from different guilds inhabiting pine tree plantations and native Atlantic Forests in South America. Following the thermal adaptation hypothesis, we predicted that generalist species would show a wider thermal tolerance range (i.e., lower CTmin and higher CTmax) than forest specialist species. As expected, generalist species showed significantly higher CTmax and lower CTmin values than specialist species with wider thermal tolerance ranges than forest specialist species. These differences are more marked in orb weavers than in aerial hunter spiders. Our study supports the specialisation disturbance and thermal hypotheses. It highlights that habitat-specialist species are more vulnerable to environmental changes associated with vegetation structure and microclimatic conditions. Moreover, thermal tolerance is a key response trait to explain the Atlantic Forest spider's ability (or inability) to colonise and persist in human-productive land uses.

Spatiotemporal Patterns of Ant Metacommunity in a Montane Forest Archipelago.

Naturally fragmented landscapes are adequate systems for evaluating patterns and mechanisms that determine species distribution without confounding effects of anthropogenic fragmentation and habitat loss. We aimed to evaluate an ant metacommunity's spatiotemporal patterns in montane forest islands amid a grassland-dominated matrix. We assessed these patterns by deconstructing the ant metacommunity into forest-dependent and habitat generalist species. We sampled twice a year (summer and winter) over 2 years (2014 and 2015), using soil and arboreal pitfall traps, in fourteen forest islands (varying in size, shape, and connectivity) in the Espinhaço Range Biosphere Reserve, Brazil. We evaluated the relationship between ant species richness, composition (ß-diversity), and predictor variables of forest island structure (canopy cover and understory density) and landscape structure (forest amount, number of forest islands, and shape). We sampled 99 ant species, 66.7% of which were classified as forest-dependent and 33.3% as habitat generalist species. We found that ant ß-diversity was higher in space than in time, and that species composition variation in time (temporal ß-diversity) differed between ant species groups. Both ant groups responded differently to forest island and landscape structure characteristics. Landscape structure seems to act as a spatial filter and the forest islands' local characteristics as an environmental filter, which jointly determine the local and regional diversity. We demonstrate the importance that forest archipelagos pose to ant metacommunity's structure and dynamics in montane tropical regions. Mountaintop conservation and management strategies must consider the forest island archipelago to maintain the biodiversity and the functioning of these systems.

Host-generalist fungal pathogens of seedlings may maintain forest diversity via host-specific impacts and differential susceptibility among tree species.

Host-specialized pathogens are credited with the maintenance of tropical forest diversity under the Janzen-Connell hypothesis. Yet, in diverse forests, selection may favor pathogens with broad host ranges, given their passive dispersal and the relative rarity of tree species. We surveyed the host associations of potential pathogens isolated from symptomatic seedlings in forests in Panama and used inoculations to assess the pathogenicity and host ranges of 27 fungal isolates, and differences among tree species in susceptibility. Thirty-one of the 33 nonsingleton operational taxonomic units (OTUs) isolated from seedlings are multi-host. All 31 multi-host OTUs exhibit low to moderate specialization, and we observed phylogenetically overdispersed host use for 19 OTUs. The pathogenicity of 10 isolates was experimentally confirmed; nine caused disease in seedlings in multiple families. However, the outcome of infection differs among tree species susceptible to a given multi-host pathogen. Furthermore, some tree species were seemingly resistant to all fungi tested, while others were susceptible to multiple fungi. Tree species adapted to environments with lower disease pressure were most likely to exhibit disease. Our results suggest that generalist pathogens contribute to the maintenance of local and regional forest diversity via host-specific impacts and the exclusion of disease-sensitive trees from disease-prone habitats.

New insights into the trophic ecology of blacktip sharks (Carcharhinus limbatus) from a subtropical estuary in the western Gulf of Mexico.

As environmental change persists, understanding resource use patterns is of value to predict the consequences of shifting trophic structures. While many sharks are opportunistic predators, some exhibit prey selectivity, putting them at higher risk compared to species with greater trophic plasticity. In the Gulf of Mexico (GOM), Clupeids and Sciaenids comprise 69% of blacktip shark (Carcharhinus limbatus) diets, which is consequential considering potential responses of these prey groups to disturbance and over harvesting. We assessed if blacktips exhibit selectivity for Clupeids and Sciaenids in the western GOM based on stomach contents from sharks in coastal Texas. Clupeids comprised <2% of diets, while striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) comprised >70% of identifiable prey. Ontogenetic shifts from smaller (Clupeids, small Sciaenids) to larger, higher trophic level (Ariidae, Elasmobranchii) prey fits our understanding of foraging among coastal sharks, and suggests our regional understanding of blacktip trophic ecology may be limited by the sizes of sampled sharks. Observed increases in blacktip densities coupled with declines in prey (Mugilids, Sciaenids) is concerning if blacktips have limited diet plasticity. Yet GOM blacktips may be more generalized than previously thought, which is promising for conservation and management.

Feeding and Mobility Traits Influence Grasshopper Vulnerability to Agricultural Production in the Cape Floristic Region Biodiversity Hotspot.

To be able to foretell which species will be at risk of extinction from possible expansion of agriculture into natural areas, we need to determine how land use affects animal groups especially insects with different life history traits. Intuitively, we can predict that the proportion of specialist versus generalist grasshoppers and widespread versus localised species can be an indicator of change in vegetation patterns in a landscape. As a result, the study examined the relationship between the extent of range distribution and mobility of grasshoppers and land-use type in the Cape Floristic Region (CFR) biodiversity hotspot. It aimed at examining grasshopper assemblage composition in association with different land uses. We specifically related the number and type of sites occupied by grasshopper species to their mobility and distribution type to find out which characters improve species survival under highly modified habitats. Grasshopper assemblages were dominated by highly mobile generalists that tolerated transformed landscapes, and mostly geographically widespread. This contrasts with the low- to medium-mobile, range-restricted specialists, which make up close to 30% of the total collection, with a lower tolerance for anthropogenically modified landscapes in the CFR. This study also reveal that the fynbos biome is an important habitat for low-mobility and range-restricted species, and hence require conscious conservation efforts to conserve such species to prevent possible future biotic erosion and homogenisation in this hotspot. This result can be used to assess the possible extent of biotic erosion or otherwise in order to recommend better conservation efforts in the CFR.

Greater pollination generalization is not associated with reduced constraints on corolla shape in Antillean plants.

Flowers show important structural variation as reproductive organs but the evolutionary forces underlying this diversity are still poorly understood. In animal-pollinated species, flower shape is strongly fashioned by selection imposed by pollinators, which is expected to vary according to guilds of effective pollinators. Using the Antillean subtribe Gesneriinae (Gesneriaceae), we tested the hypothesis that pollination specialists pollinated by one functional type of pollinator have maintained more similar corolla shapes through time due to more constant and stronger selection constraints compared to species with more generalist pollination strategies. Using geometric morphometrics and evolutionary models, we showed that the corolla of hummingbird specialists, bat specialists, and species with a mixed-pollination strategy (pollinated by hummingbirds and bats; thus a more generalist strategy) have distinct shapes and that these shapes have evolved under evolutionary constraints. However, we did not find support for greater disparity in corolla shape of more generalist species. This could be because the corolla shape of more generalist species in subtribe Gesneriinae, which has evolved multiple times, is finely adapted to be effectively pollinated by both bats and hummingbirds. These results suggest that ecological generalization is not necessarily associated with relaxed selection constraints.

Ecología trófica, dimorfismo sexual y parámetros reproductivos en el lagarto endémico Andino Liolaemus vallecurensis, Argentina / Trophic ecology, sexual dimorphism and reproductive parameters in the endemic Andean lizard Liolaemus vallecurensis, Argentina

Se evaluaron los hábitos alimenticios, dimorfismo sexual y parámetros reproductivos en Liolaemus vallecurensis (Pereyra, 1992) en un sector Andino de Argentina. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa y se calculó el Índice de Importancia Relativa (IRI). Además se aplicaron índices tróficos (Levins) e índices de diversidad. Se estudiaron las variaciones morfológicas en 14 medidas comparando machos y hembras adultos. Considerando los artrópodos, L. vallecurensis consume principalmente ítem del orden Hymenoptera (no Formicidae) no encontrándose diferencias tróficas entre sexos ni por edades. Los machos presentan tendencia hacia una estrategia de búsqueda activa y una dieta especialista. Las hembras y juveniles cazan al acecho con una dieta de tipo más oportunista. Los machos consumen grandes cantidades de materia vegetal considerándose como herbívoros aunque no estrictamente, hembras omnívoras y juveniles entre insectívoros y omnívoros. Se encontró dimorfismo entre sexos en 10 variables morfológicas. Se encontró asociación entre la longitud de cabeza y el modo de búsqueda de alimento. Se confirma la condición vivípara con un tamaño de camada de tres crías, con una parición entre fines de diciembre y principios de enero. Estos aportes en L. vallecurensis representan los primeros y únicos datos biológicos para esta especie en estos ambientes rigurosos.(AU)

The feeding habits, sexual dimorphism and reproductive parameters of Liolaemus vallecurensis (Pereyra, 1992) were assessed in an Andean sector of Argentina. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. Trophic indices (Levins) and diversity indices were applied as well. Also studied were morphological variations in 14 measurements, comparing adult males and females. In concerning arthropods, L. vallecurensis feeds mostly on items from the order Hymenoptera (not Formicidae), with no differences being found between sexes or ages. Males show a tendency towards an active search strategy and a specialized diet. Females and juveniles hunt by stalking, and have a more opportunistic diet. Males consume large amounts of plant matter considered as herbivores but not strictly, females are omnivores and juveniles between insectivores and omnivores. Dimorphism was found between sexes for 10 morphological variables. Head length and food search mode were found to be associated. A viviparous condition is confirmed by a clutch size of three young, with parturition occurring between late December and early January. These contributions to L. vallecurensis represent the first and only biological data on this species in these harsh environments.(AU)

Ecología trófica, dimorfismo sexual y parámetros reproductivos en el lagarto endémico Andino Liolaemus vallecurensis, Argentina / Trophic ecology, sexual dimorphism and reproductive parameters in the endemic Andean lizard Liolaemus vallecurensis, Argentina

Se evaluaron los hábitos alimenticios, dimorfismo sexual y parámetros reproductivos en Liolaemus vallecurensis (Pereyra, 1992) en un sector Andino de Argentina. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa y se calculó el Índice de Importancia Relativa (IRI). Además se aplicaron índices tróficos (Levins) e índices de diversidad. Se estudiaron las variaciones morfológicas en 14 medidas comparando machos y hembras adultos. Considerando los artrópodos, L. vallecurensis consume principalmente ítem del orden Hymenoptera (no Formicidae) no encontrándose diferencias tróficas entre sexos ni por edades. Los machos presentan tendencia hacia una estrategia de búsqueda activa y una dieta especialista. Las hembras y juveniles cazan al acecho con una dieta de tipo más oportunista. Los machos consumen grandes cantidades de materia vegetal considerándose como herbívoros aunque no estrictamente, hembras omnívoras y juveniles entre insectívoros y omnívoros. Se encontró dimorfismo entre sexos en 10 variables morfológicas. Se encontró asociación entre la longitud de cabeza y el modo de búsqueda de alimento. Se confirma la condición vivípara con un tamaño de camada de tres crías, con una parición entre fines de diciembre y principios de enero. Estos aportes en L. vallecurensis representan los primeros y únicos datos biológicos para esta especie en estos ambientes rigurosos.

The feeding habits, sexual dimorphism and reproductive parameters of Liolaemus vallecurensis (Pereyra, 1992) were assessed in an Andean sector of Argentina. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. Trophic indices (Levins) and diversity indices were applied as well. Also studied were morphological variations in 14 measurements, comparing adult males and females. In concerning arthropods, L. vallecurensis feeds mostly on items from the order Hymenoptera (not Formicidae), with no differences being found between sexes or ages. Males show a tendency towards an active search strategy and a specialized diet. Females and juveniles hunt by stalking, and have a more opportunistic diet. Males consume large amounts of plant matter considered as herbivores but not strictly, females are omnivores and juveniles between insectivores and omnivores. Dimorphism was found between sexes for 10 morphological variables. Head length and food search mode were found to be associated. A viviparous condition is confirmed by a clutch size of three young, with parturition occurring between late December and early January. These contributions to L. vallecurensis represent the first and only biological data on this species in these harsh environments.

Ecología trófica, dimorfismo sexual y parámetros reproductivos en el lagarto endémico Andino Liolaemus vallecurensis, Argentina

RESUMEN Se evaluaron los hábitos alimenticios, dimorfismo sexual y parámetros reproductivos en Liolaemus vallecurensis (Pereyra, 1992) en un sector Andino de Argentina. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa y se calculó el Índice de Importancia Relativa (IRI). Además se aplicaron índices tróficos (Levins) e índices de diversidad. Se estudiaron las variaciones morfológicas en 14 medidas comparando machos y hembras adultos. Considerando los artrópodos, L. vallecurensis consume principalmente ítem del orden Hymenoptera (no Formicidae) no encontrándose diferencias tróficas entre sexos ni por edades. Los machos presentan tendencia hacia una estrategia de búsqueda activa y una dieta especialista. Las hembras y juveniles cazan al acecho con una dieta de tipo más oportunista. Los machos consumen grandes cantidades de materia vegetal considerándose como herbívoros aunque no estrictamente, hembras omnívoras y juveniles entre insectívoros y omnívoros. Se encontró dimorfismo entre sexos en 10 variables morfológicas. Se encontró asociación entre la longitud de cabeza y el modo de búsqueda de alimento. Se confirma la condición vivípara con un tamaño de camada de tres crías, con una parición entre fines de diciembre y principios de enero. Estos aportes en L. vallecurensis representan los primeros y únicos datos biológicos para esta especie en estos ambientes rigurosos.

ABSTRACT The feeding habits, sexual dimorphism and reproductive parameters of Liolaemus vallecurensis (Pereyra, 1992) were assessed in an Andean sector of Argentina. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. Trophic indices (Levins) and diversity indices were applied as well. Also studied were morphological variations in 14 measurements, comparing adult males and females. In concerning arthropods, L. vallecurensis feeds mostly on items from the order Hymenoptera (not Formicidae), with no differences being found between sexes or ages. Males show a tendency towards an active search strategy and a specialized diet. Females and juveniles hunt by stalking, and have a more opportunistic diet. Males consume large amounts of plant matter considered as herbivores but not strictly, females are omnivores and juveniles between insectivores and omnivores. Dimorphism was found between sexes for 10 morphological variables. Head length and food search mode were found to be associated. A viviparous condition is confirmed by a clutch size of three young, with parturition occurring between late December and early January. These contributions to L. vallecurensis represent the first and only biological data on this species in these harsh environments.