Movement Of Organisms Research Articles

Effects of sea ice fragmentation on polar bear migratory movement in Hudson Bay

Habitat fragmentation can impede an animal’s ability to move through their habitat, affecting both local and long-distance movements. Each year, polar bears Ursus maritimus migrate to refuge habitats on land or to multiyear ice as annual sea ice breaks up. We used polar bear telemetry location data from 39 adult female polar bears tracked in Hudson Bay in 2013-2018 during break-up (2 May-23 July) to show variation in migratory movement and timing as break-up advances. We separated break-up into early and late periods and used standard deviation in temporal spatial autocorrelation (SASD) of sea ice concentration to quantify sea ice fragmentation. Higher spatial autocorrelation reflects dissimilarity in local habitat composition at a single point in time, while SASD reflects variation in local habitat composition over time. In late break-up, there was a significant positive correlation between polar bear path tortuosity and SASD. Individuals arrived on land significantly later when paths moved through sea ice with increasing SASD in late break-up. Reproductive status of adult female polar bears had no effect on the variability of the sea ice an individual travelled through. SASD provides a means of summarizing the complexity and dynamics of sea ice habitat and can be used to understand variation in movement and ecology of ice-associated organisms.

A barycentric coordinates-based visualization framework for movement of microscopic organisms

A barycentric coordinates-based visualization framework for movement of microscopic organisms

Vertical and horizontal movements of bigeye tuna (Thunnus obesus) in southeastern Taiwan

ABSTRACT To learn about the movement patterns of bigeye tuna in eastern Taiwan, pop-up satellite archival tags were attached on five tuna ~55 kg and prematurely detached and popped-up after 32 to 132 days-at-liberty. Two tags were physically recovered and provided fine-scale data archiving the full 47 and 132 days-at-liberty. The deepest descent recorded was 1,292 m and the coldest temperature visited 2.7°C. During daytime, the fish spent the majority of time above 400 m at temperatures from ~10 - 25°C and at nighttime; residency was largely confined to the mixed-layer from the surface to ~100 m. Vertical movements traversing through the thermocline during the daytime are based on physiological constraints and/or rapid directional changes conducive for optimal search strategies that increases the chances of prey encounters. Bigeye tuna appear to follow the diel vertical movements of prey organisms comprising the deep sound scattering layer to exploit them as a resource.

Motor function recovery: deciphering a regenerative niche at the neuromuscular synapse.

ABSTRACTThe coordinated movement of many organisms relies on efficient nerve–muscle communication at the neuromuscular junction (NMJ), a peripheral synapse composed of a presynaptic motor axon terminal, a postsynaptic muscle specialization, and non‐myelinating terminal Schwann cells. NMJ dysfunctions are caused by traumatic spinal cord or peripheral nerve injuries as well as by severe motor pathologies. Compared to the central nervous system, the peripheral nervous system displays remarkable regenerating abilities; however, this capacity is limited by the denervation time frame and depends on the establishment of permissive regenerative niches. At the injury site, detailed information is available regarding the cells, molecules, and mechanisms involved in nerve regeneration and repair. However, a regenerative niche at the final functional step of peripheral motor innervation, i.e. at the mature neuromuscular synapse, has not been deciphered. In this review, we integrate classic and recent evidence describing the cells and molecules that could orchestrate a dynamic ecosystem to accomplish successful NMJ regeneration. We propose that such a regenerative niche must ensure at least two fundamental steps for successful NMJ regeneration: the proper arrival of incoming regenerating axons to denervated postsynaptic muscle domains, and the resilience of those postsynaptic domains, in morphological and functional terms. We here describe and combine the main cellular and molecular responses involved in each of these steps as potential targets to help successful NMJ regeneration.

The use and misuse of regression models in landscape genetic analyses.

The field of landscape genetics has been rapidly evolving, adopting and adapting analytical frameworks to address research questions. Current studies are increasingly using regression-based frameworks to infer the individual contributions of landscape and habitat variables on genetic differentiation. This paper outlines appropriate and inappropriate uses of multiple regression for these purposes, and demonstrates through simulation the limitations of different analytical frameworks for making correct inference. Of particular concern are recent studies seeking to explain genetic differences by fitting regression models with effective distance variables calculated independently on separate landscape resistance surfaces. When moving across the landscape, organisms cannot respond independently and uniquely to habitat and landscape features. Analyses seeking to understand how landscape features affect gene flow should model a single conductance or resistance surface as a parameterized function of relevant spatial covariates, and estimate the values of these parameters by linking a single set of resistance distances to observed genetic dissimilarity via a loss function. While this loss function may involve a regression-like step, the associated nuisance parameters are not interpretable in terms of organismal movement and should not be conflated with what is actually of interest: the mapping between spatial covariates and conductance/resistance. The growth and evolution of landscape genetics as a field has been rapid and exciting. It is the goal of this paper to highlight past missteps and demonstrate limitations of current approaches to ensure that future use of regression models will appropriately consider the process being modeled, which will provide clarity to model interpretation.

Diel Variability and Influence of Artificial Light on Fish and Macroinvertebrate Communities in Gulf of Mexico Seagrass Beds

Seagrasses are productive habitats that support diverse communities of economically and ecologically important fishes and macroinvertebrates. However, most seagrass faunal assessments are conducted only during daylight hours. Here, we documented diel patterns in seagrass-associated fish and macroinvertebrate community structure in seagrass near Seahorse Key, Florida (USA). Artificial light is prevalent in many coastal areas and may influence day/night assemblages; therefore, we added lights to the natural environment to get a better understanding of its effect on community composition. Seagrass inhabitants were quantified using 25-m seine transects during different diel periods (day or night) and in areas where light was manipulated to mimic light pollution (artificial + natural light or natural light). Results suggest that the magnitude of diel effects exceeded that of light addition. While total abundance was similar between day and night, communities did change, with Lagodon rhomboides (Pinfish) dominating day samples and Farfantepenaeus duorarum (pink shrimp) most abundant at night. Other fishes such as Orthopristis chrysoptera (Pigfish) and Strongylura notata (Needlefish) had higher catches during the day, while invertebrates such as Callinectes sapidus (blue crab) and Palaeomonetes spp. (grass shrimp) were more prominent at night. In addition to the differences in abundance and community structure, we also identified diel differences in sizes for some species. No clear patterns were observed with the short-term addition of artificial light. This research highlights the role of diel variability in seagrass communities and suggests that diel movement of organisms may represent an important conduit for the transfer of energy to adjacent habitats.

The rose and the fly. A conjecture on the origin of consciousness

The Scottish philosopher Thomas Reid and more recently the evolutionary psychologist Nicholas Humphrey argued for a basic distinction between sensation (what is happening to me) and perception (what is happening out there) with the former, but not the latter, being associated with consciousness. Conscious experiences in this view would emerge from changes in the state of the body, i.e. as bodily actions, and would maintain such a primal characteristic nowadays. I argue that the evolutionary reason for the sensation/perception distinction can be traced back to organisms’ movement, and to the consequent need to tell apart two varieties of an otherwise identical local stimulation: namely, either as the outcome of external stimuli passively impinging on body surface or as the outcome of an organism movement giving rise to encountering with external stimuli. The Erich von Holst Reafferenzprinzip effectively modelled such a distinction by postulating that an efference copy is generated in association with the motor command thus nullifying any sensory signal that arises as a by-product of an organism movement. I argue that if sensation originally equates to a bodily action (or its internalized representation), then it could be that an efference copy of local (or internalized) bodily action is generated under stimulation and compared to that associated with active motor command. This way the result would be leaving sensation (what is happening to me) or nullifying it and leaving only perception (what is happening out there) depending on whether or not a motor command has occurred. Implications of this hypothesis for the presence of consciousness in animals or other organisms such as plants are briefly discussed.

Being Well-Connected Pays in a Disturbed World: Enhanced Herbivory in Better-Linked Habitats

Seascapes are typically comprised of multiple components that are functionally linked by the movement of organisms and fluxes of matter. Changes to the number and spatial arrangement of these linkages affect biological connectivity that, in turn, can alter ecological functions. Herbivory is one such function, pivotal in controlling excessive algal growth when systems become disturbed. Here, we used microcosm experiments to test how the change to connectivity affects herbivory under different levels of disturbance. We applied network theory to measure types of connectivity at different scales (patch and whole system) and quantified herbivory by a crustacean mesograzer exposed to excess algae, mimicking pulse and press disturbances. We demonstrate that greater connectivity significantly enhances herbivory in Clibanarius virescens: Both the number of linkages and their spatial arrangement interact to shape the response of herbivory in systems to disturbance. Our findings highlight the value of controlled experiments for advancing theories about the potential effects of connectivity on important ecological functions, such as herbivory, and justify further investigation to measure how connectivity might affect the resilience of ecosystems. We posit that the variation in the type, and scale, of spatial linkages might have profound consequences for managing the capacity of ecosystems to respond to disturbance.

Spatial-Temporal Analysis of the Forest Fragments Surrounding a Conservation Unit in the Southern Region of Brazil

In recent years, anthropogenic actions have intensified forest fragmentation, causing several damages to the landscape’s natural components, propagating the loss of biodiversity. This study aims to present an analysis of the forest fragments in a conservation unit located at southern of Brazil. The evaluation was carried out for the years 1998, 2008, and 2018, by using landscape metrics and classification of remote sensing imagery of the Landsat satellite. The following metrics were analyzed: area and edge, shape, core area, and aggregation. The results indicated an increase of 16.88% in the total area of vegetation, and the percentage of fragments increased from 16.16% to 18.89%. The number of fragments decreased, resulting in an increase of the mean area in 5.4 ha. The percentage of vegetation under border effect changed from 40.2% to 37.1%. In 1998, the average nearest neighbor distance was 155.4 m, and in 2018, 149.7 m. However, this distance is still classified as a high degree of isolation, which hinders the movement of organisms and the dispersion of species. Thus, all the analyzed metrics indicated a decrease in the fragmentation, except for the edge density metric, in which its increase of 1.86 pointed to a lower degree of conservation during the analyzed period. A study of this nature is important as it provides subsidies for future researches and can contribute to action strategies to be adopted in the management plan of the area.

Prey capture in protists utilizing microtubule filled processes and surface motility.

Surface motility, which can be visualized by the movement of live prey organisms, polystyrene microspheres or other inert particles, has been shown to occur in a wide variety of microtubule-filled extensions of the protistan cell surface, although the associated functions remain enigmatic. This article integrates an extensive but poorly known body of literature showing that surface motility, associated with microtubule-filled cell extensions such as flagella, axopodia, actinopodia, reticulopodia, and haptonema, plays a crucial role in protistan prey capture. Surface motility has been most extensively studied in Chlamydomonas where it is responsible for flagella-dependent whole cell gliding motility. The force transduction machinery for gliding motility in Chlamydomonas is intraflagellar transport. Other than in Chlamydomonas, this field has not moved far beyond the descriptive to the mechanistic because of technical challenges associated with many of the protistan organisms that utilize surface motility for prey capture. The purpose of this article is to rekindle interest in the protistan systems that utilize surface motility for prey capture at a time when newly emerging molecular tools for working with protists are poised to reinvigorate a field that has been quiescent too long.

Cyanobacteria and Algae in Clouds and Rain in the Area of puy de Dôme, Central France.

The atmosphere contains diverse living microbes, of which the heterotrophic community has been the best studied. Microbes with other trophic modes, such as photoautotrophy, have received much less attention. In this study, culture-independent and dependent methods were used to examine the presence and diversity of oxygenic photoautotrophic microbes in clouds and rain collected at or around puy de Dôme Mountain, central France. Cloud water was collected from the summit of puy de Dôme (1,465 m above sea level [a.s.l.]) for cultivation and metagenomic analysis. Cyanobacteria, diatoms, green algae, and other oxygenic photoautotrophs were found to be recurrent members of clouds, while green algae affiliated with the Chlorellaceae were successfully cultured from three different clouds. Additionally, rain samples were collected below the mountain from Opme meteorological station (680 m a.s.l.). The abundance of chlorophyll a-containing cells and the diversity of cyanobacteria and green algae in rain were assessed by flow cytometry and amplicon sequencing. The corresponding downward flux of chlorophyll a-containing organisms to the ground, entering surface ecosystems with rain, varied with time and was estimated to be between ∼1 and >300 cells cm-2 day-1 during the sampling period. Besides abundant pollen from Pinales and Rosales, cyanobacteria of the Chroococcidiopsidales and green algae of the Trebouxiales were dominant in rain samples. Certain members of these taxa are known to be ubiquitous and stress tolerant and could use the atmosphere for dispersal. Overall, our results indicate that the atmosphere carries diverse, viable oxygenic photoautotrophic microbes and acts as a dispersal vector for this microbial guild.IMPORTANCE Information regarding the diversity and abundance of oxygenic photoautotrophs in the atmosphere is limited. More information from diverse locations is needed. These airborne organisms could have important impacts upon atmospheric processes and on the ecosystems they enter after deposition. Oxygenic photoautotrophic microbes are integral to ecosystem functioning, and some have the potential to affect human health. A better understanding of the diversity and the movements of these aeolian dispersed organisms is needed to understand their ecology, as well as how they could affect ecosystems and human health.

Individual specialization in the use of space by frugivorous bats.

Natural populations are not homogenous systems but sets of individuals that occupy subsets of the species' niche. This phenomenon is known as individual specialization. Recently, several studies found evidence of individual specialization in animal diets. Diet is a critical dimension of a species' niche that affects several other dimensions, including space use, which has been poorly studied under the light of individual specialization. In this study, which harnesses the framework of the movement ecology paradigm and uses yellow-shouldered bats Sturnira lilium as a model, we ask how food preferences lead individual bats of the same population to forage mainly in different locations and habitats. Ten individual bats were radiotracked in a heterogeneous Brazilian savanna. First, we modelled intraspecific variation in space use as a network of individual bats and the landscape elements visited by them. Second, we developed two novel metrics, the spatial individual specialization index (SpatIS) and the spatial individual complementary specialization index (SpatICS). Additionally, we tested food-plant availability as a driver of interindividual differences in space use. There was large interindividual variation in space use not explained by sex or weight. Our results point to individual specialization in space use in the studied population of S. lilium, most probably linked to food-plant distribution. Individual specialization affects not only which plant species frugivores consume, but also the way they move in space, ultimately with consequences for seed dispersal and landscape connectivity.

Peering into the Cuba phytosanitary black box: An institutional and policy analysis.

To mitigate the movement of non-native organisms with trade, phytosanitary systems have been implemented within and between countries. In some countries such as Cuba, little is known about the within-state plant health system. To facilitate the development of future trade partnership between Cuba and the United States, agencies need to understand the organizational structure and diagnostic capacity of the Cuban Plant Protection System, identify potential synergies between the United States and Cuban systems, and identify steps towards cooperation. This paper fills this critical void by presenting a descriptive analysis of the plant health system in Cuba. Information was integrated from available literature, informal interviews with Cuban experts, and workshops focused on Cuban policies, risk, and potential collaboration attended by Cuban and American experts. We identify the next practical steps in improving cooperation, including building trust and capacity. Mutual understanding of phytosanitary systems will be crucial for the regional economic and environmental stability of a post-embargo United States-Cuban relationship.

House mouse Mus musculus dispersal in East Eurasia inferred from 98 newly determined complete mitochondrial genome sequences

The Eurasian house mouse Mus musculus is useful for tracing prehistorical human movement related to the spread of farming. We determined whole mitochondrial DNA (mtDNA) sequences (ca. 16,000 bp) of 98 wild-derived individuals of two subspecies, M. m. musculus (MUS) and M. m. castaneus (CAS). We revealed directional dispersals reaching as far as the Japanese Archipelago from their homelands. Our phylogenetic analysis indicated that the eastward movement of MUS was characterised by five step-wise regional extension events: (1) broad spatial expansion into eastern Europe and the western part of western China, (2) dispersal to the eastern part of western China, (3) dispersal to northern China, (4) dispersal to the Korean Peninsula and (5) colonisation and expansion in the Japanese Archipelago. These events were estimated to have occurred during the last 2000–18,000 years. The dispersal of CAS was characterised by three events: initial divergences (ca. 7000–9000 years ago) of haplogroups in northernmost China and the eastern coast of India, followed by two population expansion events that likely originated from the Yangtze River basin to broad areas of South and Southeast Asia, including Sri Lanka, Bangladesh and Indonesia (ca. 4000–6000 years ago) and to Yunnan, southern China and the Japanese Archipelago (ca. 2000–3500). This study provides a solid framework for the spatiotemporal movement of the human-associated organisms in Holocene Eastern Eurasia using whole mtDNA sequences, reliable evolutionary rates and accurate branching patterns. The information obtained here contributes to the analysis of a variety of animals and plants associated with prehistoric human migration.

Risky Business: Live Non-CITES Wildlife UK Imports and the Potential for Infectious Diseases.

Simple SummaryThe UK imports wild animals for commercial purposes from countries all across the world. We analyse a database of wildlife records from the UK’s Animal and Plant Health Agency (APHA) to summarise the volume and variety of non-CITES (Convention on International Trade in Endangered Species) listed wild animal imports over a recent 5-year period (2014–2018). We found that over 48 million individual animals were imported into the UK from 90 countries across nine global regions from 2014–2018. In terms of volume (semi-domesticated pigeons and game birds aside), amphibians were the most commonly imported group (73%), followed by reptiles (17%), mammals (4%), and birds (3%). The highest number of import records came from Europe and Africa, but the largest volume of animals came from North America and Asia. We review the potential for infectious diseases emerging from these vast and varied wildlife imports and discuss the potential threats they pose to public health. We also draw attention to an observed current lack of detail in the APHA database and suggest that better record keeping and reporting could help prevent and manage the introduction of infectious diseases.International wildlife trade is recognised as a major transmission pathway for the movement of pathogenic organisms around the world. The UK is an active consumer of non-native live wild animals and is therefore subject to the risks posed by pathogen pollution from imported wildlife. Here, we characterise a key yet overlooked portion of the UK wildlife import market. We evaluate the trade in live non-CITES (Convention on International Trade in Endangered Species) wild terrestrial animals entering the UK over a 5-year period using data reported by the Animal and Plant Health Agency (APHA). Between 2014 and 2018, over 48 million individual animals, across five taxonomic classes and 24 taxonomic orders, were imported into the UK from 90 countries across nine global regions. The largest volumes of wild animals were imported from North America and Asia, and most of the import records were from Europe and Africa. Excluding Columbiformes (pigeons) and Galliformes (‘game birds’), amphibians were the most imported taxonomic class (73%), followed by reptiles (17%), mammals (4%), birds (3%), and arachnids (<1%). The records described herein provide insight into the scope and scale of non-CITES listed wildlife imported in to the UK. We describe the potential for pathogen pollution from these vast and varied wildlife imports and highlight the potential threats they pose to public health. We also draw attention to the lack of detail in the UK wildlife import records, which limits its ability to help prevent and manage introduced infectious diseases. We recommend that improved record keeping and reporting could prove beneficial in this regard.

An acoustic method to observe the distribution and behaviour of mesopelagic organisms in front of a trawl

We describe a method to allow acoustic sampling at depths not reachable by the higher frequencies of ship hull-mounted echosounders and observe the abundance and behaviour of individual organisms in front of trawls. A self-contained scientific echosounder with a 120 kHz transducer was mounted forward-facing on the headline of a macrozooplankton trawl that was obliquely towed from 0 to 1000 m depth, to investigate the mesopelagic fauna. With the use of a forward-facing echosounder, we were able to estimate organism densities in front of the trawl, the vertical profiles of organism target strength and the movement of organisms in front of the trawl. We demonstrate that a forward-facing trawl-mounted echosounder is a simple and useful method to investigate the distribution of mesopelagic fauna at depth.

A Review on the Qualitative Behavior of Solutions in Some Chemotaxis–Haptotaxis Models of Cancer Invasion

Chemotaxis is an oriented movement of cells and organisms in response to chemical signals, and plays an important role in the life of many cells and microorganisms, such as the transport of embryonic cells to developing tissues and immune cells to infection sites. Since the pioneering works of Keller and Segel, there has been a great deal of literature on the qualitative analysis of chemotaxis systems. As an important extension of the Keller–Segel system, a variety of chemotaxis–haptotaxis models have been proposed in order to gain a comprehensive understanding of the invasion–metastasis cascade. From a mathematical point of view, the rigorous analysis thereof is a nontrivial issue due to the fact that partial differential equations (PDEs) for the quantities on the macroscale are strongly coupled with ordinary differential equations (ODEs) modeling the subcellular events. It is the goal of this paper to describe recent results of some chemotaxis–haptotaxis models, inter alia macro cancer invasion models proposed by Chaplain et al., and multiscale cancer invasion models by Stinner et al., and also to introduce some open problems.

The Mouse Levator Auris Longus Muscle: An Amenable Model System to Study the Role of Postsynaptic Proteins to the Maintenance and Regeneration of the Neuromuscular Synapse.

The neuromuscular junction (NMJ) is the peripheral synapse that controls the coordinated movement of many organisms. The NMJ is also an archetypical model to study synaptic morphology and function. As the NMJ is the primary target of neuromuscular diseases and traumatic injuries, the establishment of suitable models to study the contribution of specific postsynaptic muscle-derived proteins on NMJ maintenance and regeneration is a permanent need. Considering the unique experimental advantages of the levator auris longus (LAL) muscle, here we present a method allowing for efficient electroporation-mediated gene transfer and subsequent detailed studies of the morphology and function of the NMJ and muscle fibers. Also, we have standardized efficient facial nerve injury protocols to analyze LAL muscle NMJ degeneration and regeneration. Our results show that the expression of a control fluorescent protein does not alter either the muscle structural organization, the apposition of the pre- and post-synaptic domains, or the functional neurotransmission parameters of the LAL muscle NMJs; in turn, the overexpression of MuSK, a major regulator of postsynaptic assembly, induces the formation of ectopic acetylcholine receptor clusters. Our NMJ denervation experiments showed complete reinnervation of LAL muscle NMJs four weeks after facial nerve injury. Together, these experimental strategies in the LAL muscle constitute effective methods to combine protein expression with accurate analyses at the levels of structure, function, and regeneration of the NMJ.

Outcomes of wildlife translocations in protected areas: what is the type and extent of existing evidence? A systematic map protocol

BackgroundConversion, fragmentation, and loss of natural habitats are among the main causes of declining species’ populations worldwide. Protected areas are therefore crucial for biodiversity as they provide refuge and ensure key ecological processes. Wildlife translocations, defined as “the deliberate movement of organisms from one site for release in another”, have been used in conjunction as a conservation tool for a number of decades as wild populations become increasingly fragmented and endangered. Not only are translocations used to bolster the viability of imperiled species but are also recommended for improving population resilience and adapting species’ ranges in response to climate change. Despite translocation being a recognised conservation tool, it remains complex with variable results due to the different factors that can determine its success. Accordingly, the Map will investigate the existing evidence on the links between different types of wildlife translocation interventions and factors that may be important to consider for planning. This will provide an overview of relevant studies for possible future syntheses, and may help to inform management decisions.MethodWe will perform a thorough search of peer-reviewed journal articles and grey literature sources documenting the occurrence of translocations in the context of protected areas. Two databases will be used: Web of science core collection and Scopus, with a supplementary search in Google Scholar. Multiple key specialized websites will also be used. All bibliographic data will be extracted, managed, and screened in Microsoft excel. Three screening stages will be undertaken (title, then abstract, then full texts) against predefined inclusion criteria. The retained relevant literature will be subjected to coding and meta-data extraction. No formal validity appraisal will be undertaken. The Map will particularly highlight translocation operations in terms of origin and destination (i.e. translocating from one protected area to another, within the same area, and from and to non-protected areas) by taxonomic group, among other important factors (e.g. number of individuals, age class, release strategy, distance between capture and release sites etc.). Finally, a database will be provided along with a Map narratively describing the evidence with summary figures and tables of pertinent study characteristics.

Effects of transportation infrastructure on fishes in the Ozark and Ouachita Mountains

Rivers worldwide are fragmented by transportation infrastructure that blocks the movements of aquatic organisms. To assess the effects of road culverts on stream fishes in the Ozark and Ouachita Mountains regions of Oklahoma, we surveyed 39 free-flowing sites, 29 sites upstream and 29 sites downstream of culverts. We observed differences in species richness and abundance between free-flowing sites, sites upstream of a culvert, and downstream sites. We also found that the degree to which a culvert affected richness and abundance depended on culvert type and length. Furthermore, the culverts in the poorest condition had the greatest effects on abundance and richness. Replacement of these poor condition culverts is likely a high priority for both conservation groups and infrastructure agencies. Our findings enable conservation practitioners to identify structures that may be high priorities for aquatic organism passage projects, including those that may benefit from cost-sharing or collaboration with infrastructure agencies.