Ecosystems wherein social and solitary predators share space, complex asymmetric intraguild interactions actively shape the group size of social carnivores. Intense intraguild predation has been known to result in reduced group size and low recruitment rates in subordinate social carnivores. In South and South-east Asia, Dhole, tiger and leopard form a widely distributed sympatric guild of large carnivores. In this paper we attempted to understand the pack size dynamics of a subordinate social predator, the dhole, by investigating factors underlying pack size variation at two neighbouring sites. We further evaluated our local-scale patterns of pack size variation at a larger scale by doing a distribution-wide assessment of pack size across dhole ranging countries. Across study sites, we found an inverse relationship between the local abundance of a top predator and group size of a subordinate predator while accounting for variability in resources and habitat heterogeneity. Tiger density was low (0.71/100 Km2) at the site having large dhole packs (16.8 ± 3.1) whereas, a relatively smaller average dhole pack size (6.4 ± 1.3) was observed in a higher tiger density (5.67/100 Km2) area. Our results on distribution-wide assessment are concurrent with local-scale results, showing a positive association between prey abundance and pack size and a negative association between tiger densities and dhole pack size. Our study takes us one step closer to trying to answer the age-old question of what drives the pack size of social predators in a multi-predator system. Linking behaviour to population dynamics and carnivore interactions is another highlight of the study. Often helpful while optimizing conservation triage and formulation of management implications like recovery and translocations.
The desert harvester ant Veromessor pergandei displays geographic variation in colony founding with queens initiating nests singly (haplometrosis) or in groups (pleometrosis). The transition from haplo- to pleometroic founding is associated with lower rainfall. Numerous hypotheses have been proposed to explain the evolution of cooperative founding in this species, but the ultimate explanation remains unanswered. In laboratory experiments, water level was positively associated with survival, condition, and brood production by single queens. Queen survival also was positively influenced by water level and queen number in a two-factor experiment. Water level also was a significant effect for three measures of queen condition, but queen number was not significant for any measure. Foundress queens excavated after two weeks of desiccating conditions were dehydrated compared to alate queens captured from their natal colony, indicating that desiccation can be a source of queen mortality. Long-term monitoring in central Arizona, USA, documented that recruitment only occurred in 4 of 20 years. A discriminant analysis using rainfall as a predictor of recruitment correctly predicted recruitment in 17 of 20 years for total rainfall from January–June (the period for mating flights and establishment) and in 19 of 20 years for early plus late rainfall (January–March and April–June, respectively), often with a posterior probability > 0.90. Moreover, recruitment occurred only in years in which both early and late rainfall exceeded the long-term mean. This result also was supported by the discriminant analysis predicting no recruitment when long-term mean early and late rainfall were included as ungrouped periods. These data suggest that pleometrosis in V. pergandei evolved to enhance colony survival in areas with harsh abiotic (desiccating) conditions, facilitating colonization of habitats in which solitary queens could not establish even in wet years. This favorable-year hypothesis supports enhanced worker production as the primary advantage of pleometrosis.
Seabirds, particularly Procellariiformes, are highly mobile organisms with a great capacity for long dispersal, though simultaneously showing high philopatry, two conflicting characteristics that may lead to contrasted patterns of genetic population structure. Landmasses were suggested to explain differentiation patterns observed in seabirds, but philopatry, isolation-by-distance, segregation between breeding and non-breeding zones, and oceanographic conditions (sea surface temperatures) may also contribute to differentiation patterns. No study has simultaneously contrasted the multiple factors contributing to the diversification of seabird species, especially in the grey zone of speciation. We conducted a multi-locus phylogeographic study on a widespread shearwater species complex (Puffinus lherminieri/bailloni), showing highly homogeneous morphology. We sequenced three mitochondrial and six nuclear markers on all extant populations (five nominal lineages, 13 populations). We found sharp differentiation among populations separated by the African continent with both mitochondrial and nuclear markers, while only mitochondrial markers allowed characterizing the five nominal lineages. No differentiation could be detected within these five lineages, questioning the strong level of philopatry showed by these shearwaters. Finally, we propose that Atlantic populations likely originated from the Indian Ocean. Within the Atlantic, a stepping-stone process accounts for the current distribution. Based on our divergence times estimates, we suggest that the observed pattern of differentiation mostly resulted from variation in sea surface temperatures.
Diet analysis of potential small mammals pest species is important for understanding feeding ecology and evaluating their impact on crops and stored foods. Chinese mole shrew (Anourosorex squamipes), distributed in Southwest China, has previously been reported as a farmland pest. Effective population management of this species requires a better understanding of its diet, which can be difficult to determine with high taxonomic resolution using conventional microhistological methods. In this study, we used two DNA metabarcoding assays to identify 38 animal species and 65 plant genera from shrew stomach contents, which suggest that A. squamipes is an omnivorous generalist. Earthworms are the most prevalent (>90%) and abundant (>80%) food items in the diverse diet of A. squamipes. Species of the Fabaceae (frequency of occurrence [FO]: 88%; such as peanuts) and Poaceae (FO: 71%; such as rice) families were the most common plant foods identified in the diet of A. squamipes. Additionally, we found a seasonal decrease in the diversity and abundance of invertebrate foods from spring and summer to winter. Chinese mole shrew has a diverse and flexible diet throughout the year to adapt to seasonal variations in food availability, contributing to its survival even when food resources are limited. This study provides a higher resolution identification of the diet of A. squamipes than has been previously described and is valuable for understanding shrew feeding ecology as well as evaluating possible species impacts on crops.
The rapid shift to online teaching in spring 2020 meant most of us were teaching in panic mode. As we move forward with course planning for fall and beyond, we can invest more time and energy into improving the online experience for our students. We advocate that instructors use inclusive teaching practices, specifically through active learning, in their online classes. Incorporating pedagogical practices that work to maximize active and inclusive teaching concepts will be beneficial for all students, and especially those from minoritized or underserved groups. Like many STEM fields, Ecology and Evolution shows achievement gaps and faces a leaky pipeline issue for students from groups traditionally underrepresented in science. Making online classes both active and inclusive will aid student learning and will also help students feel more connected to their learning, their peers, and their campus. This approach will likely help with performance, retention, and persistence of students. In this paper we offer strategies and techniques that weave together active and inclusive teaching practices and challenge faculty to commit to making small changes in the fall as a first step to more inclusive teaching in ecology and evolutionary biology courses.
Body mass is often viewed as a proxy of past access to resources and of future survival and reproductive success. Links between body mass and survival or reproduction are, however, likely to differ between age classes and sexes. Remarkably, this is rarely taken into account in selection analyses. Selection on body mass is likely to be the primary target accounting for juvenile survival until reproduction but may weaken after recruitment. Males and females also often differ in how they use resources for reproduction and survival. Using a long-term study on yellow-bellied marmots (Marmota flaviventer), we show that body mass was under stabilizing selection in the first years of life, before recruitment, which changed to positive directional selection as age increased and animals matured. We found no evidence that selection across age-classes on body mass differed between sexes. By investigating the link between running speed and body mass, we show that the capacity to escape predators was not consistent across age classes and followed a quadratic relationship at young ages only. Overall, our results indicate that mature age classes exhibit traditional patterns of positive selection on body mass, as expected in a hibernating mammal, but that mass in the first years of life is subject to stabilizing selection which may come from additional predation pressures that negate the benefits of the largest body masses. Our study highlights the importance to disentangle selection pressures on traits across critical age (or life) classes.
1. Ongoing intensification and fragmentation of European agricultural landscapes dramatically reduce biodiversity and associated functions. To sustain ecosystem services such as ant mediated pest control, the enhancement of perennial non-crop areas holds great potential. 2. To study the potential of newly established grasslands to enhance ant diversity and associated functions, we used hand collection data to investigate differences in ant community composition (a) between cereal crops, old grasslands, and new grassland transects of three years age; (b) depending on ant functional traits; and linked to (c) natural pest control services quantified through predation experiments. 3. Ant species richness did not significantly differ between new and old grasslands, but was significantly higher in grasslands compared to cereal crops. Contrary, ant community composition of new grasslands was more similar to cereal crops and distinct from the species-pool of old grasslands. The functional trait space covered by the ant communities overlapped between old and new grasslands but was extended in the old grasslands. Pest control did not differ significantly between habitat types, and therefore could not be linked to the prevalence of functional traits related to biocontrol services in new grasslands. 4. Our findings show trends of convergence between old and new grasslands, but also indicate that enhancing ant diversity through newly established grasslands takes longer than three years to provide comparable biodiversity and functions. 5. Synthesis and applications Newly established grasslands can increase ant species richness, abundance, and pest control in agroecosystems. However, three years after establishment, new grasslands were still dominated by common agrobiont ant species and lacked habitat specialists present in old grasslands, who require a constant supply of food resources and long colonization times. New grasslands represent a promising measure for enhancing agricultural landscapes but must be preserved in the longer term to sustain biodiversity and associated ecosystem services.
Prey monitor surrounding dangers independently or cooperatively (synchronized and coordinated vigilance), with independent and synchronized scanning being prevalent. Coordinated vigilance, including unique sentinel behaviour, is rare in nature, since it is time-consuming and benefit-limited. Evidence does not indicate animals adopting alternative vigilance strategies during antipredation scanning. Considering the cooperative nature of both synchronization and coordination, we assessed whether group members could keep alert synchronously or coordinatedly under different circumstances, determining whether cooperative vigilance is context dependent. Under the framework of conservation behavior, we studied how human behaviour and species-specific variables impacted individual and collective vigilance of globally threatened Black-necked Cranes (Grus nigricollis) and explored behaviour-based wildlife management. We tested both predation risk (juveniles in group) and human disturbance (level and distance) effects on individual and collective antipredation vigilance of black-necked crane families. Adults spent significantly more time (proportion and duration) on scanning than juveniles, and parents with juveniles behaved more vigilant. Observer distance affected individual vigilance of adults while juveniles were influenced by none of these variables. With the number of juveniles and disturbance increased, crane couples decreased synchronization of vigilance and they shifted to coordination, which has so far never been reported yet. Similarly, with observer approaching, adults shift vigilance from synchronization to coordination. The collective vigilance shift from synchronization to coordination as a function of observer distance could help us determining a safe distance of c. 400m for the most vulnerable family groups with two juveniles, so as no obvious interference with the threatened birds by human proximity. We argue that vigilance behaviour could be a reliable indicator in future nature-based tourist management and decision-making, which can be derived from conservation solutions in nature.
The analysis of stable isotope composition is an important tool in research on plant physiological ecology. However, large-scale patterns of leaf stable isotopes for aquatic macrophytes have received considerably less attention. In this study, we examined the spatial pattern of the leaf δ13C and δ15N of macrophytes collected across the arid zone of northwestern China and tried to illustrate how they were affected by different environmental factors. Our results showed that the mean values of leaf δ13C and δ15N in the macrophytes sampled from the arid zone were -24.49‰ and 6.82‰, respectively, which were drastically higher than the values of terrestrial plants. In addition, leaf δ13C varied significantly among different life forms, possibly reflecting the complex photosynthetic fixation and adaptations of macrophytes. In addition to, our studies indicated that the foliar δ13C values of all the aquatic macrophytes were only negatively associated with precipitation, but the foliar δ15N values were mainly associated with temperature, precipitation and potential evapotranspiration. Therefore, we speculated that the determinant of the leaf δ13C of macrophytes in the arid zone of northwestern China is water factors and the leaf δ15N values is the complex combination of water and energy factors.
Huanglongbing (HLB) is the most devastating citrus disease worldwide. The causal organism of the disease is spread by an insect vector, Diaphorina citri, commonly known as Asian citrus psyllid (ACP). Current management of HLB relies either on physical removal of the infected plants or on chemical control of ACP. Both methods are not overly effective and costly. In addition, public concerns regarding insecticide residues in fruit have greatly increased in recent years. It has been hypothesized that plant volatiles could act as repellents to ACP, thus reduce the incidence of HLB. To test this hypothesis, the repellency of fresh tissues of 41 aromatic plant species to ACP was investigated. The repellency of individual species was determined using a Y-tube olfactometer. Our results showed that volatiles of five plant species were highly effective in repelling ACP with repellency as much as 76%. Among these, the tree species, Camptotheca acuminate, and the two shrubs, Lantana camara and Mimosa bimucronata, could potentially be planted as a landscape barrier. The two herbs, Capsicum annuum and Gynura bicolor, could potentially be used as interrow plantings in orchards. This is the first time that the repellency of fresh tissues from a diverse range of plant species to ACP has been determined. Although further field evaluation of various interplanting regimes and landscape barriers are needed to assess their effectiveness, our results showed that these aromatic species, being highly repellent to ACT, offer great potential as more cost-effective and environmentally sustainable alternatives to the current methods of managing HLB.
Interspecific hybrid frequencies can vary considerably across contact zones of a single pair of progenitor species. The reasons for this are not well understood, but could help explain processes such as species diversification or the range expansion of invasive hybrids. The widespread cattails Typha latifolia and T. angustifolia seldom hybridize in some parts of their range, but in other areas produce the dominant hybrid T. × glauca. We used a combination of field and greenhouse experiments to investigate why T. × glauca has invaded wetlands in the Laurentian Great Lakes region of southern Ontario, Canada, but is much less common in the coastal wetlands of Nova Scotia in eastern Canada. One potentially important environmental difference between these two regions is salinity. We therefore tested three hypotheses: 1) T. latifolia and T. angustifolia in Nova Scotia are genetically incompatible; 2) the germination or growth of T. × glauca is reduced by salinity; and 3) T. latifolia, a main competitor of T. × glauca, is locally adapted to saline conditions in Nova Scotia. Our experiments showed that Nova Scotia T. latifolia and T. angustifolia are genetically compatible, and that saline conditions do not impede growth of hybrid plants. However, we also found that under conditions of high salinity, germination rates of hybrid seeds were substantially lower than those of Nova Scotia T. latifolia. In addition, germination rates of Nova Scotia T. latifolia were higher than those of Ontario T. latifolia, suggesting local adaptation to salinity in coastal wetlands. This study adds to the growing body of literature which identifies the important roles that local habitat and adaptation can play in the distributions and characteristics of hybrid zones.
The utility of elevational gradients as tools to test either ecological hypotheses and delineate elevation-associated environmental factors that explain the species diversity patterns is critical for moss species conservation. We examined the elevational patterns of species richness and evaluated the effects of spatial and environmental factors on moss species predicted a priori by alternative hypotheses, including mid-domain effect (MDE), habitat complexity, energy, and environment proposed to explain the variation of diversity. Last, we assessed the contribution of elevation toward explaining the heterogeneity among sampling sites. We observed the hump-shaped distribution pattern of species richness along elevational gradient. The MDE and the habitat complexity hypothesis were supported with MDE being the primary driver for richness patterns, whereas little support was found for the energy, and the environment. Moss species richness pattern in the mountain is driven by ecological and evolutionary effects, whereas evolutionary factors predominately shape the large heterogeneity through dispersal, extinction and speciation processes.
Climate change is expected to systematically alter the distribution and poEurycea pulation dynamics of species around the world. The effects are expected to be particularly strong at high latitudes and elevations, and for ectothermic species with small ranges and limited movement potential, such as salamanders in the southern Appalachian Mountains. In this study, we sought to establish baseline abundance estimates for plethodontid salamanders (family: Plethodontidae) over an elevational gradient in Great Smoky Mountains National Park. In addition to generating these baseline data for multiple species, we describe methods for surveying salamanders that allow for meaningful comparisons over time by separating observation and ecological processes generating the data. We found that Plethodon jordani had a mid-elevation peak (1500 m) in abundance and Desmognathus wrighti increased in abundance with elevation up to the highest areas of the park (2025 m), whereas Eurycea wilderae increased in abundance up to 1600 m and then plateaued with increasing uncertainty. In addition to elevation, litter depth, herbaceous ground cover, and proximity to stream were important predictors of abundance (dependent upon species), whereas daily temperature, precipitation, ground cover, and humidity influenced detection rates. Our data provide some of the first minimally biased information for future studies to assess changes in the abundance and distribution of salamanders in this region. Understanding abundance patterns along with detailed baseline distributions will be critical for comparisons with future surveys to understand the population and community-level effects of climate change on montane salamanders.
1. Studies on the effects of human-driven forest disturbance usually focus on either biodiversity or carbon dynamics but much less is known about ecosystem processes that integrate trophic levels. Herbivory is one fundamental ecological process for ecosystem functioning that remains underexplored and is poorly quantified in human-modified tropical rainforests. 2. Here, we present the results of the largest study to date on the impacts of human disturbances on herbivory. We quantified the incidence and severity of herbivory caused by chewers, miners and gall-formers in 199,869 canopy leaf blades from 1,102 trees distributed across 20 forest plots located along a gradient of human disturbance in the Amazon. 3. We found that chewers dominated herbivory incidence, yet were not a good predictor of the other forms of herbivory either at the stem or plot level. Herbivory severity was correlated with disturbance intensity, being greater at more disturbed sites. 4. Synthesis. Although our large-scale study of canopy herbivory in Amazonian forests suggests that human disturbance increases the severity of leaf herbivory, effects were weak. Additionally, we found no effect of human disturbance in incidence of leaf herbivory. These results combined indicate that herbivory is a relatively resilient process to human impacts.
This spring, instructors moved their courses online in an emergency fashion as campuses were closed due to the pandemic. As colleges prepare for the next academic year, there is a need to provide flexible instruction that is more intentional for quality online learning. We taught two undergraduate courses online for the first time this spring and surveyed our students’ reactions to the course experiences. From our experiences and student feedback we identified design elements and activities that were beneficial in promoting student engagement, sense of connectivity, and learning. We describe four qualities for a successful transition to online learning: 1) big questions and core concepts; 2) peer groups including reflective writing; 3) outreach to broader scientific community; and 4) instructor’s social presence in the class. Our experience gives us confidence that courses can be redesigned for online without compromising rigor or essential learning goals.
The investigation of ecological processes that maintain species coexistence is important in harsh environments, as they act as strong drivers of species selection. Congeneric species are a good model to investigate the relative importance of such processes, as closely related species tend to have similar niches. We aim to find evidence for the action and relative importance of different ecological processes hypothesized to maintain species coexistence in a tropical forest subject to seasonal flooding, using the spatial structure of populations of three congeneric species. We collected data on a 1-ha plot of a Brazilian white-sand flooded tropical forest, where individuals of three Myrcia species were tagged, mapped, and measured for diameter at soil height. We also sampled seven environmental variables in the plot. We employed several spatial point pattern models to simultaneously investigate habitat filtering, interspecific competition, stochasticity, and dispersal limitation. Habitat filtering was the most important process driving the local distribution of the species, as they showed associations, albeit of different strength, to environmental variables related to flooding. We did not detect spatial patterns consistent with interspecific competition, i.e. spatial segregation and smaller size of nearby congeners. The three species do not seem to show evidence of stochasticity even though congeners were spatially independent, since they responded to differences in the environment. Last, dispersal limitation only led to spatial associations of different size classes for one of the species. Using data from congeneric species in a harsh environment as a model, we demonstrated that habitat filtering to areas subject to flooding is the most important ecological process driving the local distribution of the species studied in a white-sand forest. Even though many studies on topo-edaphic variation in tropical forests have shown that habitat filtering is an important ecological process, other processes that drive community structuring may have gone undetected.
Experience and training in field work is a critical component of undergraduate education in ecology, and many university courses incorporate field-based or experiential components into the curriculum in order to provide students hands-on experience. Due to the onset of the COVID-19 pandemic and the sudden shift to remote instruction in the spring of 2020, many instructors of such courses found themselves struggling to identify strategies for developing rigorous field activities that could be completed online, solo, and from a student’s backyard. This case study illustrates the process by which one field-based course, a UC California Naturalist certification course offered at the University of California, Davis, transitioned to fully remote instruction. The transition relied on established, publicly available, online participatory science platforms (e.g., iNaturalist) to which the students contributed data and observations remotely. Student feedback on the course and voluntary continued engagement with the participatory science platforms indicates that the student perspective of the experience was on par with previous traditional offerings of the course. This case study also includes topics and participatory science resources for consideration by other faculty facing a similar transition from group field activities to remote, individual field-based experiences.
COVID-19 created a host of challenges for science education; in our case, the pandemic halted our in-person elementary school outreach project on bird biology. This project was designed as a year-long program to teach fifth grade students in Ithaca, New York, USA about bird ecology and biodiversity, using outdoor demonstrations and in-person games and activities to engage students in nature. As a central part of this effort, we set up nest boxes on school property and had planned to monitor them with students during bird breeding in the spring. Here, we describe our experiences transitioning this program online: we live streamed nest boxes to students’ virtual classrooms and used them as starting points for virtual lessons on bird breeding and nestling development. We suggest that instituting similar programs at local schools can promote equitable learning opportunities for students across geographical locations and with various living situations. In an era of social distancing and isolation, we propose that nest box live streaming and virtual lessons can support local communities by providing access to the outdoors and unconventional science learning opportunities for all students.