Agricultural intensification alters bat assemblage composition and abundance in a dynamic Neotropical landscape

The recent trend of agricultural intensification in tropical landscapes poses a new threat to biodiversity conservation. Conversion of previously heterogeneous agricultural landscapes to intensive plantation agriculture simplifies and homogenizes the landscape, reducing availability, and connectivity of natural habitat for native species. To assess the impact of agricultural intensification on bats, we characterized the bat assemblage in the Sarapiquí region of Costa Rica, where heterogeneous land uses are being converted to intensive, large‐scale pineapple plantations. In 2012 and 2013, we sampled bats in 20 remnant forest patches surrounded by varying proportions of pasture, mature forest, and pineapple and captured 1821 individual bats representing 39 species. We used ordination analyses to evaluate changes in species composition, where pineapple is the main component of the agricultural matrix. We identified landscape metrics specifically correlated with pineapple and used multiple linear regression to test their effects on bat species richness, diversity, and guild‐specific relative abundance. Results suggest pineapple expansion is driving changes in assemblage composition in remnant forest patches, resulting in new assemblages with higher proportions of frugivorous bats and lower proportions of insectivorous bats than in continuous mature forests. In addition, while pineapple does not diminish total bat species richness and diversity, the reduced forest cover and increased distance between forest patches in pineapple plantations has a significant negative impact on the relative abundance of insectivores. We also identify a potential threshold effect whereby patches surrounded by more than 50 percent forest can retain assemblage composition similar to that found in continuous mature forest.     

The effect of two cryopreservation methods on human sperm DNA damage

Several methods are currently available for selection when conducting sperm cryopreservation, however, these methods might cause different degrees of damage on sperm DNA. The aim of the this study is to compare the effects of storage at −80 °C (in ultra-low temperature refrigerator) and at −196 °C (in liquid nitrogen) on sperm DNA damage, thus to provide a reference for choosing the right method according to different aims. We randomly collected 28 semen samples from college students of Chongqing city. The samples stored at −80 °C were neat semen samples and the samples stored at −196 °C were mixed with additional cryoprotectants. Each sample was subjected to two freezing-thawing cycles, and the sperm DNA damage levels of fresh and thawed samples were measured by single cell gel electrophoresis (SCGE) and sperm chromatin structure assay (SCSA). Both SCGE and SCSA assays showed cryopreservation induced significant damage to sperm DNA. However, storage at −196 °C lead to more severe damage to sperm DNA than storage at −80 °C measured by SCSA. Sperm DNA damage increased simultaneously with the higher frequency of freezing-thawing cycles. We concluded that storage of neat semen samples at −80 °C had milder damage to sperm DNA than storage at −196 °C mixed with cryoprotectants. To avoid additional sperm DNA damage, repeated freezing and thawing should be prevented.     

Spatial metrics effect of forest fragmentation on forest bird abundance and site occupancy probability: the influence of patch size and isolation

The persistence of species taxa within fragmented habitats is dependent on the source–sink metapopulation processes, and forest patch size and isolation are key factors. Unveiling species–patch area and/or species–patch isolation relationships may help provide crucial information for species and landscape management. In this study, relationship between forest patch size and isolation with abundance and occupancy probability of forest-dependent birds was investigated. This study was based within a coastal landscape that faces deleterious human activities such as clearing for agriculture. The study aimed to answer the question of whether the size and extent of isolation of forest patches influence abundance and/or occupancy probability of forest-specialist and generalist birds. Two bird species, namely Tiny Greenbul Phyllastrephus debilis subsp. rabai and Yellow-bellied Greenbul Chlorocichla flaviventris, were used as models. Birds were surveyed using distance sampling methods, and spatial metrics were measured from satellite imagery. Focal forest size and distance between forest patches were the most influential metrics whereby abundance and occupancy probabilities increased with increasing patch size, but were negatively influenced by increasing gaps between patches. These findings provide evidence of the existence of patch size/ isolation–occupancy relationships characterised by higher occupancy rate of large patches and distance-dependent dispersal, which decreased with increasing gaps between patches. Controlling deleterious human activities that reduce forest size should be a priority for the long-term conservation of forest-dependent birds.     

Circadian rhythm of autophagy proteins in hippocampus is blunted by sleep fragmentation

Autophagy is essential for normal cellular survival and activity. Circadian rhythms of autophagy have been studied in several peripheral organs but not yet reported in the brain. Here, we measured the circadian rhythm of autophagy-related proteins in mouse hippocampus and tested the effect of sleep fragmentation (SF). Expressions of the autophagy-related proteins microtubule‐associated protein 1 light chain 3 (LC3) and beclin were determined by western blotting and immunohistochemistry. Both the hippocampal LC3 signal and the ratio of its lipid-conjugated form LC3-II to its cytosolic form LC3-I showed a 24 h rhythm. The peak was seen at ZT6 (1 pm) and the nadir at ZT16 (1 am). The LC3 immunoreactivity in hippocampal CA1 pyramidal neurons also distributed differently, with more diffuse cytoplasmic appearance at ZT16. Chronic SF had a mild effect to disrupt the 24 h rhythm of LC3 and beclin expression. Interestingly, a greater effect of SF was seen after 24 h of recovery sleep when LC3-II expression was attenuated at both the peak and trough of circadian activities. Overall, the results show for the first time that the hippocampus has a distinct rhythm of autophagy that can be altered by SF.     

Beauty before age: landscape factors influence bird functional diversity in naturally regenerating fragments,but regeneration age does not

Effective ecological restoration actions should be able to recover ecosystem processes that influence community development in the long term. However, there is scarce information on how landscape factors promote or accelerate fauna recovery. We used a landscape framework to evaluate how functional groups respond to natural regeneration in a highly fragmented region of Atlantic Forest. Using bird functional groups sampled in 15 regenerating forest fragments, we built and ranked models using a model selection approach to test the relative effect of landscape variables on each group. Our results showed that bird community recovery is not determined by the duration of the regeneration process (i.e. forest age), but by how the species responds to the landscape context. Functional diversity and the abundance of the functional groups were mainly related to composition metrics, whereas the functional metric affected only specific groups. Our findings highlight the importance of considering the landscape level to ensure both the colonization of fauna and the restoration of ecological functions.     

A global assessment of primate responses to landscape structure

Land‐use change modifies the spatial structure of terrestrial landscapes, potentially shaping the distribution, abundance and diversity of remaining species assemblages. Non‐human primates can be particularly vulnerable to landscape disturbances, but our understanding of this topic is far from complete. Here we reviewed all available studies on primates' responses to landscape structure. We found 34 studies of 71 primate species (24 genera and 10 families) that used a landscape approach. Most studies (82%) were from Neotropical forests, with howler monkeys being the most frequently studied taxon (56% of studies). All studies but one used a site‐landscape or a patch‐landscape study design, and frequently (34% of studies) measured landscape variables within a given radius from the edge of focal patches. Altogether, the 34 studies reported 188 responses to 17 landscape‐scale metrics. However, the majority of the studies (62%) quantified landscape predictors within a single spatial scale, potentially missing significant primate–landscape responses. To assess such responses accurately, landscape metrics need to be measured at the optimal scale, i.e. the spatial extent at which the primate–landscape relationship is strongest (so‐called ‘scale of effect’). Only 21% of studies calculated the scale of effect through multiscale approaches. Interestingly, the vast majority of studies that do not assess the scale of effect mainly reported null effects of landscape structure on primates, while most of the studies based on optimal scales found significant responses. These significant responses were primarily to landscape composition variables rather than landscape configuration variables. In particular, primates generally show positive responses to increasing forest cover, landscape quality indices and matrix permeability. By contrast, primates show weak responses to landscape configuration. In addition, half of the studies showing significant responses to landscape configuration metrics did not control for the effect of forest cover. As configuration metrics are often correlated with forest cover, this means that documented configuration effects may simply be driven by landscape‐scale forest loss. Our findings suggest that forest loss (not fragmentation) is a major threat to primates, and thus, preventing deforestation (e.g. through creation of reserves) and increasing forest cover through restoration is critically needed to mitigate the impact of land‐use change on our closest relatives. Increasing matrix functionality can also be critical, for instance by promoting anthropogenic land covers that are similar to primates' habitat.     

Managing the middle: A shift in conservation priorities based on the global human modification gradient

An increasing number of international initiatives aim to reconcile development with conservation. Crucial to successful implementation of these initiatives is a comprehensive understanding of the current ecological condition of landscapes and their spatial distributions. Here, we provide a cumulative measure of human modification of terrestrial lands based on modeling the physical extents of 13 anthropogenic stressors and their estimated impacts using spatially explicit global datasets with a median year of 2016. We quantified the degree of land modification and the amount and spatial configuration of low modified lands (i.e., natural areas relatively free from human alteration) across all ecoregions and biomes. We identified that fewer unmodified lands remain than previously reported and that most of the world is in a state of intermediate modification, with 52% of ecoregions classified as moderately modified. Given that these moderately modified ecoregions fall within critical land use thresholds, we propose that they warrant elevated attention and require proactive spatial planning to maintain biodiversity and ecosystem function before important environmental values are lost.     

Looking to the future: key points for sustainable management of northern Great Plains grasslands

The grasslands of the northern Great Plains (NGP) region of North America are considered endangered ecosystems and priority conservation areas yet have great ecological and economic importance. Grasslands in the NGP are no longer self‐regulating adaptive systems. The challenges to these grasslands are widespread and serious (e.g. climate change, invasive species, fragmentation, altered disturbance regimes, and anthropogenic chemical loads). Because the challenges facing the region are dynamic, complex, and persistent, a paradigm shift in how we approach restoration and management of the grasslands in the NGP is imperative. The goal of this article is to highlight four key points for land managers and restoration practitioners to consider when planning management or restoration actions. First, we discuss the appropriateness of using historical fidelity as a restoration or management target because of changing climate, widespread pervasiveness of invasive species, the high level of fragmentation, and altered disturbance regimes. Second, we highlight ecosystem resilience and long‐term population persistence as alternative targets. Third, because the NGP is so heavily impacted with anthropogenic chemical loading, we discuss the risks of ecological traps and extinction debt. Finally, we highlight the importance of using adaptive management and having patience during restoration and management. Consideration of these four points will help management and restoration of grasslands move toward a more successful and sustainable future. Although we specifically focus on the NGP of North America, these same issues and considerations apply to grasslands and many other ecosystems globally.     

Benthic ctenophore (Order Platyctenida) reproduction,recruitment, and seasonality in south Florida

Reproductive structures, modes, and seasonal patterns of size–class abundances are examined in two benthic platyctene (Family Coeloplanidae) ctenophore species present in dissimilar shallow marine environments in subtropical southeast Florida. Coeloplana waltoni, a minute (1–3 mm body length) epizoic associate of octocorals, occurs in exposed environments often under turbulent conditions, and Vallicula multiformis (2–10 mm) commonly occurs epiphytically on macroalgae in protected, calm‐water environments. Reproductive activity in C. waltoni is most active during the warm‐water summer season (June–October); gonadal development in V. multiformis occurs year‐round, and is most pronounced during sea‐warming periods in late spring (May) and late summer to early autumn (August–October), with release of cydippid larvae. Both species are hermaphroditic brooders, exhibiting paedogenesis (early gonadal development) at body lengths approximately one‐third (Coeloplana) to one‐sixth (Vallicula) of maximum adult size. Juvenile individuals (<0.6 mm) increased in abundance in C. waltoni during the summer reproductive period, and large (≥1 mm) pink‐colored individuals comprised 50% or more of samples from July through September. Seasonal abundance of gravid individuals and the timing of cydippid larval release in V. multiformis did not correspond closely with juvenile or adult population densities. Asexual fragmentation occurred in both ctenophore species, but was observed more frequently in individuals of V. multiformis. This asexual mode of reproduction probably accounted in part for the discordance between ctenophore abundances and larval recruitment events by sexual means. Morphological structures and behaviors associated with reproduction are described in this study. Uncommon images of reproductive products (gametes, embryos, larvae), spawning events, brooding, and asexual fragmentation are included, some for the first time in the published literature.