Real-World Applications for Virtual Fences – What Are Potential Benefits for Conservation?

Livestock grazing can enhance biodiversity and ecosystem services in agricultural landscapes. In many parts of Europe, however, grazing has lost its importance, especially in the dairy sector. Large proportions of permanent grassland have been converted to arable land or intensified by fertilization and frequent defoliation. The disappearance of large herbivores and extensively grazed pastures contributes to the loss of structural, functional and biological diversity and ecosystem services. Modern technologies, which circumvent the cost- and labour-intensive installation of physical fences, could facilitate a precise spatio-temporal management of livestock and promote grazing. We reviewed the literature on the state-of-the-art of virtual fencing, focusing on the prospects of these technologies to enhance environmentally-friendly livestock farming. Novel virtual fencing technologies are expected to entail various ecological benefits, but this has rarely been tested in practice. Future experiments not only need to increase sample sizes and study periods to evaluate the long-term effectiveness of virtual fencing, but also need to be specifically designed for answering questions of conservation interest. Virtual fences have the potential to reconcile agronomic with ecological demands and bring livestock back into the landscape, but whether they will actually find broad application depends on further multidisciplinary research on animal welfare, agronomic, social and legal aspects

Wild Red Deer Benefit the Conservation of European Semi-Natural Open Habitats

Traditional land use practices have shaped European landscapes for millennia. Agricultural intensification and declining popularity of pastoral farming in the past century have resulted in a tremendous loss of extensively used open landscapes and associated biodiversity. Today, conservation management needs to prevent secondary succession of many open habitats. Large or inaccessible target areas unsuitable for conventional conservation measures might benefit from grazing by wild herbivores, which do not require fencing nor regular welfare monitoring. In a military training area in Germany, we studied the quantitative and qualitative effects of wild red deer in two protected open habitat types (lowland hay meadows and European dry heaths) based on grazing exclusion experiments over three years. Using movable exclusion cages, we showed that the amount of biomass annually removed by red deer was similar to the forage removal in livestock-based conservation grazing systems. Mown grasslands were particularly attractive to red deer owing to enhanced productivity and forage quality, suggesting that red deer grazing activities can be influenced by mowing. In addition, we compared the vegetation development in grasslands and heathlands with and without red deer grazing using open and permanently fenced plots. Grassland plant diversity decreased in fenced plots. In both habitat types, different structural vegetation characteristics, e.g. increasing sward and litter height, indicated successional developments when red deer grazing was excluded. Our results substantiate that allowing red deer access to open landscapes could not only alleviate potential conflicts with forestry, but can also promote open vegetation structure and diversity, thus providing a valuable contribution to the conservation management of semi-natural habitats

A new and morphologically distinct population of cavernicolous Poecilia mexicana (Poeciliidae: Teleostei)

The cave molly, Poecilia mexicana, from the Cueva del Azufre, a sulfur cave in Tabasco, Mexico, ranks among the best-studied cave fishes worldwide, despite being known from a single population only. Here we describe a newly discovered second population of cave-dwelling P. mexicana from a nearby, but mostly non-sulfidic cave (Luna Azufre). Despite apparent similarities between the two populations (such as reduced eye diameter and reduced pigmentation), a geometric morphometric analysis revealed pronounced morphological differentiation between the two cave form

Sex-specific local life-history adaptation in surface- and cave-dwelling Atlantic mollies (Poecilia mexicana)

Cavefishes have long been used as model organisms showcasing adaptive diversification, but does adaptation to caves also facilitate the evolution of reproductive isolation from surface ancestors? We raised offspring of wild-caught surface- and cave-dwelling ecotypes of the neotropical fish Poecilia mexicana to sexual maturity in a 12-month common garden experiment. Fish were raised under one of two food regimes (high vs. low), and this was crossed with differences in lighting conditions (permanent darkness vs. 12:12 h light:dark cycle) in a 2 × 2 factorial design, allowing us to elucidate potential patterns of local adaptation in life histories. Our results reveal a pattern of sex-specific local life-history adaptation: Surface molly females had the highest fitness in the treatment best resembling their habitat of origin (high food and a light:dark cycle), and suffered from almost complete reproductive failure in darkness, while cave molly females were not similarly affected in any treatment. Males of both ecotypes, on the other hand, showed only weak evidence for local adaptation. Nonetheless, local life-history adaptation in females likely contributes to ecological diversification in this system and other cave animals, further supporting the role of local adaptation due to strong divergent selection as a major force in ecological speciation

Red Deer Browsing Decelerates Shrub Regrowth Despite Increasing Wolf Presence

Semi-natural open habitats in Europe have been shaped by traditional land use practices, such as extensive mowing or livestock grazing. However, socio-economic transformations have led to the abandonment of many grassland and heathland areas and conservation management is now required to maintain these biodiverse habitats. Grazing by wild red deer (Cervus elaphus) can be a convenient alternative to laborious mechanical management or livestock grazing. Yet it remains unclear if free-ranging ungulates can counteract shrub growth sufficiently to maintain open habitats—especially with natural predators, i.e. wolves (Canis lupus), recolonizing Europe. To assess red deer effects on shrub regrowth after clearance, we installed a cohort of open and fenced plots (17 pairs) in 2016, when wolf presence in our study area (Grafenwöhr military training area, DE) was negligible. When wolf presence had become frequent in 2020, we set up a second cohort (41 paired plots). For both cohorts, the vegetation in the shrub and herb layer was significantly higher in fenced than open plots already after one year. Shrub height increased continuously and dead herbaceous biomass accumulated under red deer exclusion. Consequently, wild red deer can slow down shrub succession in open habitats even under increasing predation pressure. Regardless of wolf presence, a wildlife management that enables red deer to forage in open landscapes could thus reduce the required frequency of conservation management interventions

Terahertz Frequency Combs Exploiting an On-Chip, Solution-Processed, Graphene-Quantum Cascade Laser Coupled-Cavity.

The ability to engineer quantum-cascade-lasers (QCLs) with ultrabroad gain spectra, and with a full compensation of the group velocity dispersion, at terahertz (THz) frequencies, is key for devising monolithic and miniaturized optical frequency-comb-synthesizers (FCSs) in the far-infrared. In THz QCLs four-wave mixing, driven by intrinsic third-order susceptibility of the intersubband gain medium, self-locks the optical modes in phase, allowing stable comb operation, albeit over a restricted dynamic range (∼20% of the laser operational range). Here, we engineer miniaturized THz FCSs, comprising a heterogeneous THz QCL, integrated with a tightly coupled, on-chip, solution-processed, graphene saturable-absorber reflector that preserves phase-coherence between lasing modes, even when four-wave mixing no longer provides dispersion compensation. This enables a high-power (8 mW) FCS with over 90 optical modes, through 55% of the laser operational range. We also achieve stable injection-locking, paving the way to a number of key applications, including high-precision tunable broadband-spectroscopy and quantum-metrology