Ecological impacts of climate change on the snow leopard (Panthera unica) in South Asia

Snow leopard (Panthera unica) is a felid which lives in the highly rugged areas of alpine regions in different mountain ranges of South and Central Asia. This solitary animal needs large spaces for its ranges but due to climate change and relatively faster rate of global warming in South Asian mountain ranges, its habitat is going to shrink and fragment by tree-line shifts and change in hydrology of the area. Vegetative modification of montane flora and competition with domestic goats will create its prey’s population to decline along with a chance of a direct conflict and competition with the common leopard. Common leopard being more adaptable, grouped, and larger in size can be a significant stressor for a smaller and solitary snow leopard. Habitat would shrink, and snow leopard can possibly move upslope or northward to central Asian ranges and their predicted migratory patterns are unknown.

A Review: Recent Progress in the Design and Development of Nonlinear Radars

This paper presents an extensive review of nonlinear response-based radar systems. Nonlinear radars are generally used for clutter suppression purposes. These radars detect the nonlinear response generated by diodes and transistors are used as a tag for target localization. Utilizing the nonlinearity properties of these devices, these radars have been used for purposes including locating humans trapped in earthquakes and avalanches, identifying migratory patterns of animals, examining the flight pattern of bees, and detecting bugs in electronic devices. This paper covers the utilization of these radars in human vital signs monitoring, detecting targets in a clutter-rich environment, etc. State-of-the-art nonlinear radars’ high-level architectures, design challenges, and limitations are discussed here. Recent works and results obtained by the authors are also summarized.

Decapod crustaceans from the lower Miocene Qom Formation of the Isfahan area, Central Iran

From the lower Miocene (Burdigalian) of the Qom Formation, exposed in three sections (Kuh-e-Donbeh, Bagher-Abad, and Vartun) in Central Iran, a deca-pod crustacean assemblage is described. The specimens exhibit two modes of preservation: carapaces (either isolated or with attached appendages) and isolated cheliped elements. All studied specimens are fractured and/or eroded. Based on this moderately preserved material, three brachyuran crab taxa are identified, including Mursia cf. lienharti (Bachmayer, 1962), Palaeocarpilius rugifer Stoliczka, 1871, and Necronectes sp. The occurrence of P. rugifer represents the youngest confirmed occurrence of the species, whereas other two taxa represent the first confirmed Iranian occurrences of respec-tive genera. This report enriches our knowledge on Miocene decapod assemblages of Iran, and thus helping to better understand the decapod migratory patterns along the Tethyan Sea-way.

Mechanistic movement models identify continuously updated autumn migration cues in Arctic caribou

Background Migrations in temperate systems typically have two migratory phases, spring and autumn, and many migratory ungulates track the pulse of spring vegetation growth during a synchronized spring migration. In contrast, autumn migrations are generally less synchronous and the cues driving them remain understudied. Our goal was to identify the cues that migrants use in deciding when to initiate migration and how this is updated while en route. Methods We analyzed autumn migrations of Arctic barren-ground caribou (Rangifer tarandus) as a series of persistent and directional movements and assessed the influence of a suite of environmental factors. We fitted a dynamic-parameter movement model at the individual-level and estimated annual population-level parameters for weather covariates on 389 individual-seasons across 9 years. Results Our results revealed strong, consistent effects of decreasing temperature and increasing snow depth on migratory movements, indicating that caribou continuously update their migratory decision based on dynamic environmental conditions. This suggests that individuals pace migration along gradients of these environmental variables. Whereas temperature and snow appeared to be the most consistent cues for migration, we also found interannual variability in the effect of wind, NDVI, and barometric pressure. The dispersed distribution of individuals in autumn resulted in diverse environmental conditions experienced by individual caribou and thus pronounced variability in migratory patterns. Conclusions By analyzing autumn migration as a continuous process across the entire migration period, we found that caribou migration was largely related to temperature and snow conditions experienced throughout the journey. This mechanism of pacing autumn migration based on indicators of the approaching winter is analogous to the more widely researched mechanism of spring migration, when many migrants pace migration with a resource wave. Such a similarity in mechanisms highlights the different environmental stimuli to which migrants have adapted their movements throughout their annual cycle. These insights have implications for how long-distance migratory patterns may change as the Arctic climate continues to warm.

Spatial modulation of individual behaviors enables an ordered structure of diverse phenotypes during bacterial group migration

Coordination of diverse individuals often requires sophisticated communications and high-order computational abilities. Microbial populations can exhibit diverse individualistic behaviors, and yet can engage in collective migratory patterns with a spatially sorted arrangement of phenotypes. However, it is unclear how such spatially sorted patterns emerge from diverse individuals without complex computational abilities. Here, by investigating the single-cell trajectories during group migration, we discovered that, despite the constant migrating speed of a group, the drift velocities of individual bacteria decrease from the back to the front. With a Langevin-type modeling framework, we showed that this decreasing profile of drift velocities implies the spatial modulation of individual run-and-tumble random motions, and enables the bacterial population to migrate as a pushed wave front. Theoretical analysis and stochastic simulations further predicted that the pushed wave front can help a diverse population to stay in a tight group, while diverse individuals perform the same type of mean reverting processes around centers orderly aligned by their chemotactic abilities. This mechanism about the emergence of orderly collective migration from diverse individuals is experimentally demonstrated by titration of bacterial chemoreceptor abundance. These results reveal a simple computational principle for emergent ordered behaviors from heterogeneous individuals.

Multidimensional natal isotopic niches reflect migratory patterns in birds

Naturally occurring stable isotope ratios in animal tissues allow estimation of species trophic position and ecological niche. Measuring multiple isotopes of migratory species along flyway bottlenecks offers the opportunity to sample multiple populations and species whose tissues carry information at continental scales. We measured δ2H, δ18O, δ13C, δ15N in juvenile feathers of 21 bird species captured at a migratory bottleneck in the Italian Alps. We examined if trends in individual isotopes reflected known migratory strategies and whether dietary (δ13C–δ15N) and spatially-explicit breeding origin (δ2H–δ18O) niche breadth (NB) differed among long-distance trans-Saharan (TS), short-distance (IP) and irruptive (IR) intra-Palearctic migrants, and whether they correlated with reported populations long-term trends. In both TS and IP groups, species δ2H declined with capture date, indicating that northern populations reached the stopover site later in the season, following a Type-I migration strategy. Values of δ2H indicated that breeding range of TS migrants extended farther north than IP and IR migrants. The breeding season was longer for IP migrants whose δ13C and δ15N values declined and increased, respectively, with time of capture. Average species dietary NB did not differ among migratory groups, but TS migrants displayed wider breeding origin niches, suggesting that long-distant migration is linked to broader ecological niches. Isotope origin NB well reflected species geographic range extent, while dietary NB did not correlate with literature accounts of species’ diet. We found no relationship between species breeding NB and population trends in Europe, suggesting that conditions in the breeding grounds, as inferred by stable isotopes, are not the only determinant of species’ long-term persistence. We demonstrate that ringing activities and isotopic measurements of passerines migrating through a bottleneck represents a unique opportunity to investigate large-scale life-history phenomena relevant to conservation.

Trans-Saharan Migration Through and From the Sahel

This chapter describes the dynamics of trans-Saharan migration in relation to the migratory policies implemented in the Sahel in the second decade of the twenty-first century. It argues that the circulation of migrants between the Sahara’s northern and southern edges is not a new phenomenon even though it has intensified and diversified in recent decades. It pays particular attention to the migration policies implemented in Sahelian countries under pressure from the European Union and other partners, with the goal of containing the migration of nationals as well as persons from other countries who are passing through the Sahel. The chapter discusses how the focus on securitization of borders is leading to the criminalization of migration in transit countries. It then analyzes the repercussions of these policies on the conditions for migration, the longstanding migratory patterns in this zone, and the region’s unsteady socioeconomic equilibrium.

Gun Island: A Tale of Myth, Migration and Climate Change

Gun Island is a story of travel and migrations, overlaid with myth and folktales, and the deepening crisis of climate change. It presents an intricately interwoven plot which connects human and animal, past and present, natural and the supernatural. This paper attempts to explore how the notion of interconnectedness manifests itself in each of these elements. Gun Island uses the myth of the Gun Merchant as a nexus to draw parallels between the Little Ice Age and our present-day scenario where droughts, floods, cyclones, wildfires and epidemics have become a part of our everyday lives. Gun Island projects unprecedented climatic conditions as the primary cause for these natural disasters. It becomes a clarion call for climate induced migrations as it skillfully portrays people and entire communities being uprooted from their native land and the drastic changes in the migratory patterns of different species due to changing climes and warming waters. Instead of projecting warnings of impending doom and apocalypse Gun Island focuses on giving the readers hope for a better tomorrow.

Seq Your Destiny: Neural Crest Fate Determination in the Genomic Era

Neural crest stem/progenitor cells arise early during vertebrate embryogenesis at the border of the forming central nervous system. They subsequently migrate throughout the body, eventually differentiating into diverse cell types ranging from neurons and glia of the peripheral nervous system to bones of the face, portions of the heart, and pigmentation of the skin. Along the body axis, the neural crest is heterogeneous, with different subpopulations arising in the head, neck, trunk, and tail regions, each characterized by distinct migratory patterns and developmental potential. Modern genomic approaches like single-cell RNA- and ATAC-sequencing (seq) have greatly enhanced our understanding of cell lineage trajectories and gene regulatory circuitry underlying the developmental progression of neural crest cells. Here, we discuss how genomic approaches have provided new insights into old questions in neural crest biology by elucidating transcriptional and posttranscriptional mechanisms that govern neural crest formation and the establishment of axial level identity. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.