Terrestrial Populations Research Articles

Individual behaviour, growth, survival and vulnerability to hunting in a large mammal.

Humans have exploited wild animals for thousands of years. Recent studies indicate that harvest-induced selection on life-history and morphological traits may lead to ecological and evolutionary changes. Less attention has been given to harvest-induced selection on behavioural traits, especially in terrestrial systems. We assessed in a wild population of large terrestrial mammals whether decades of hunting led to harvest-induced selection on trappability, a proxy of risk-taking behaviour. We investigated links between trappability, horn growth and survival across individuals in early life and quantified the correlations between early-life trappability and horn growth with availability to hunters and probability of being shot. We found positive among-individual correlations between early-life trappability and horn growth, early-life trappability and survival and early-life horn growth and survival. Faster growing individuals were more likely to be available to hunters and shot at a young age. We found no correlations between early-life trappability and availability to hunters or probability of being shot. Our results show that correlations between behaviour and growth can occur in wild terrestrial population but may be context dependent. This result highlights the difficulty in formulating general predictions about harvest-induced selection on behaviour, which can be affected by species ecology, harvesting regulations and harvesting methods used. Future studies should investigate mechanisms linking physiological, behavioural and morphological traits and how this effects harvest vulnerability to evaluate the potential for harvest to drive selection on behaviour in wild animal populations.

Spider Diversity (Arachnida: Araneae) in Suhelwa Wildlife Sanctuary’s Different Ecosystems, Terai Region, Uttar Pradesh, India

Spiders are essential parts of all ecosystems in which they exist, and they’re recognized to be good markers of the diversity and health of terrestrial populations. However, the Suhelwa Wildlife Sanctuary’s spiders are poorly documented, with hardly any information on their systematics, diversity, or ecology. The current study aims to look into the spider faunal richness in a few habitats in the Suhelwa Wildlife Sanctuary in Uttar Pradesh, India. The chosen environments yielded a total of 65 species, divided into 46 genera and 20 families. The maximum species richness was found at Razia Taal (Site C), while the lowest was found at Hathiakunda Naala (Site D). The spiders were divided into seven functional categories based on their guild structure: stalkers, orb-web builders, ambushers, space-web builders, ground runners, foliage runners, and sheet-web builders. Finally, the highest species richness is linked to the flora and fauna of these locations. The findings of this study provide useful and up-to-date information on the diversity of species found in the Suhelwa Wildlife Sanctuary, and the data may be used for future spider research.

Murky waters: Assessing the vulnerabilities of Indo‐West Pacific non‐marine elasmobranchs to inform future conservation planning priorities

Abstract Globally, freshwater environments are imperilled, with freshwater vertebrate species declining at twice the rate of marine and terrestrial populations. Non‐marine elasmobranchs (freshwater obligates and euryhaline generalists) remain understudied and overlooked by conservation efforts. This study aimed to adapt and apply a vulnerability assessment framework to understand the conservation priorities of Indo‐West Pacific non‐marine elasmobranch species. An exposure sensitivity adaptability (ESA) framework was used to assess vulnerability to environmental threats, and an exposure susceptibility productivity (ESP) framework was used to assess vulnerability to fisheries. Resulting species vulnerabilities were categorized into three conservation priority tiers. The general patterns of conservation priority tiering were as follows: (i) large‐bodied euryhaline species occurring in densely populated nations had the highest ESA and ESP vulnerabilities; (ii) freshwater obligates also had high ESA vulnerability rankings, although ESP vulnerability rankings were lower as their smaller body sizes suggest increased population productivity and higher potential for resilience; and (iii) euryhaline species with large range proportions in northern Australia had moderate to low vulnerability rankings across ESA and ESP assessments, as these species benefit from reduced fisheries mortality compared with species occurring in other regions. The outcomes from the vulnerability assessment framework for the conservation priority rankings of species corresponded with their respective International Union for Conservation of Nature (IUCN) Red List status, whereby priority 1 and 2 species also have elevated extinction risks. Environmental threats were at high or moderate levels in all nations assessed, while Cambodia, China, Malaysia, and Myanmar face the highest pressure from inland fisheries. The major knowledge gaps identified included species‐specific productivity estimates, population dynamics (population movements and habitat requirements), and information on mortality from the threats considered. The present ESA–ESP framework was effective for the broad and data‐poor context of Indo‐West Pacific non‐marine elasmobranchs, and the results will be useful for guiding future conservation planning for high‐priority species and nations.

Integrative Genomics Sheds Light on Global Deep Terrestrial Biosphere Communities

Active microbial lineages inhabit the deep terrestrial subsurface (Fry et al. 1997, Lopez-Fernandez et al. 2018) with estimates suggesting deep subsurface ecosystems to host ca. 90% of the total bacterial and archaeal biomass on Earth and about 10-20% of all terrestrial biomass (McMahon and Parnell 2014, Bar-On et al. 2018, Magnabosco et al. 2018, Drake and Reiners 2021). This highlights deep subsurface ecosystems as a vast reservoir of genetic innovation that remains poorly characterized. The biological diversity of deep subsurface ecosystems seem to be influenced by parameters such as temperature, pressure, water residence times, and geochemistry (Drake and Reiners 2021). The deep subsurface environment remains underrepresented in metagenomic databases, and yet the publicly available datasets are not synoptically analyzed in an integrated way. In this project, we collected a large set of publicly available and published metagenomes, published metagenome assembled genomes (MAGs) as well as single cell amplified genomes (SAGs) originating from global deep oligotrophic terrestrial subsurface samples (>70 m). Reconstructed MAGs/SAGs from this survey were integrated in to our own existing Fennoscandian Shield Genomic Database (FSGD) (Holmfeldt et al. 2021, Mehrshad et al. 2021). This expanded global database of the deep oligotrophic terrestrial subsurface contains >4000 MAGs/SAGs. In this dataset, representatives of phyla Firmicutes, Desulfobacterota, Patescibacteria, and Chlroflexota were the most prevalent taxa. The presence of Candidatus Desulforudis audaxviator across different continents and samples highlighted its adaptation to different deep biosphere environments. In addition, novel bacterial lineages at the class level were identified in several locations, pointing to the importance and necessity of further studies to characterize deep biosphere microbial diversity. This extensive study of the global deep oligotrophic terrestrial subsurface will reveal whether deep terrestrial populations are ubiquitous and how their distribution patterns are affected by different physicochemical variables such as water types and geology. By Identifying key populations present across multiple global groundwaters, our study will advance our understanding of the global diversity hosted in deep oligotrophic terrestrial subsurface ecosystems.

Lifecycle mission safety for space nuclear systems

The development of novel space nuclear systems by governments and companies can greatly enhance space exploration, commerce, and defense capabilities. However, the predominant safety framework for space nuclear in soft law and in practice focuses narrowly on launch safety. A Lifecycle Mission Safety Framework provides a new heuristic to guide system designers, mission planners, regulators, and international law for safety across the broad range of space nuclear applications. It expands safety goals beyond protection of the terrestrial population to workers and astronauts, as well as to activities in orbital space and planetary surfaces. By defining mission phases and identifying safety considerations in each, this framework provides for proactive identification and management of risk.

Reactive persistence, spatial management, and conservation of metapopulations: An application to seagrass restoration.

Assessing the conditions for persistence of spatially structured populations, especially those that are exploited by humans or threatened by global change, is of critical importance to inform management and conservation efforts. Observations for entire metapopulations are usually incomplete and rarely, if ever, sufficiently long to deduce population persistence from spatial patterns of abundance. Instead, insights based on metapopulation theory are often used for interpreting the demographic trajectories of real populations and for informing management decisions. The classical theoretical tool used to assess conditions for metapopulation persistence is the "invasibility criterion," which characterizes the asymptotic, or long-term, stability of a small colonizing population. Essentially, when the linear operator governing the metapopulation dynamics of an invasion event has a positive eigenvalue, recovery and resistance to extinction (resilience) are implied. The converse, however, is not necessarily the case-an invasion may grow over multiple generations, even when the eigenvalues indicate that extinction will eventually occur, a situation referred to here as "reactive persistence." For the management, restoration, and conservation of real metapopulations subject to continual disturbance, this transient behavior is often more relevant than the asymptotic behavior over long time scales. We develop the theoretical tools for assessing reactive persistence, demonstrating how the conditions for asymptotic and reactive persistence differ in both the patch-occupancy models suited to many terrestrial populations and those where local patch extinctions can be disregarded in the dynamics, often suited to marine species. After presenting the mathematical basis for generalizing the invasibility criterion to include reactive persistence, we illustrate how these concepts and tools can be applied in practice, using as a case study the population ecology and restoration of the seagrass Zostera muelleri (Irmisch ex Ascherson, 1867) in the Port of Gladstone in the Great Barrier Reef World Heritage Area Australia. It is shown how the analysis of the transient dynamics of the Z. muelleri metapopulation can be used to guide restoration efforts. Moreover, it is demonstrated that these reactive persistence concepts provide a more appropriate basis for site prioritization for restoration interventions than traditional stability analysis.

Metal Exposure and Sex Shape the Fatty Acid Profile of Midges and Reduce the Aquatic Subsidy to Terrestrial Food Webs.

Aquatic micropollutants can be transported to terrestrial systems and their consumers by emergent aquatic insects. However, micropollutants, such as metals, may also affect the flux of physiologically important polyunsaturated fatty acids (PUFAs). As certain PUFAs have been linked to physiological fitness and breeding success of terrestrial consumers, reduced fluxes from aquatic systems could affect terrestrial populations and food webs. We chronically exposed larvae of the aquatic insect Chironomus riparius to a range of environmentally relevant sediment contents of cadmium (Cd) or copper (Cu) in a 28-day microcosm study. Since elevated water temperatures can enhance metals' toxic effects, we used two temperature regimes, control and periodically elevated temperatures (heat waves) reflecting an aspect of climate change. Cd and Cu significantly reduced adult emergence by up to 95% and 45%, respectively, while elevated temperatures had negligible effects. Both metal contents were strongly reduced (∼90%) during metamorphosis. Furthermore, the chironomid FA profile was significantly altered during metamorphosis with the factors sex and metal exposure being relevant predictors. Consequently, fluxes of physiologically important PUFAs by emergent adults were reduced by up to ∼80%. Our results suggest that considering fluxes of physiologically important compounds, such as PUFAs, by emergent aquatic insects is important to understand the implications of aquatic micropollutants on aquatic-terrestrial meta-ecosystems.

Rare Production of Seeds by Invasive Alternanthera philoxeroides (Alligator Weed) in North America Observed in Terrestrial Populations

Rare Production of Seeds by Invasive Alternanthera philoxeroides (Alligator Weed) in North America Observed in Terrestrial Populations

The ancient inhabitants of the Chonos Archipelago (~43°–47°S): Characterization of maritime hunter‐gatherers from Western Patagonia using mitochondrial DNA

AbstractBackgroundWithin the southern end of South America, Western Patagonia arises as an intricate region of channels, fjords, and islands. This region holds evidence of human occupation since ca. 14,500 cal years BP, with distinctive maritime adaptations developing around 7300 cal years BP. Historically, three major populations were characterized as part of these maritime traditions: Yámana, Kawésqar, and Chono. The arrival of European population had a profound impact in these communities, affecting their lifestyles, territory and population size and health. The northernmost populations, living within the Chonos Archipelago, were the most affected and the least known communities from Western Patagonia.ObjectivesThis research aims to characterize the mitochondrial DNA diversity of ancient individuals from the Chonos Archipelago, evaluating their genetic affinities with other ancient and present‐day populations from Patagonia.Materials and MethodsA total of 46 individuals from the region were sampled for ancient DNA analysis. Mitochondrial DNA haplogroups were characterized and compared with ancient and present‐day populations from Southern South America.ResultsAll individuals from the Chonos Archipelago belong to C and D haplogroups, particularly to C1b, C1b13, D1, D1g, and D4h3a5. As a group, the individuals from Chonos Archipelago lay closer to ancient individuals from Kawésqar territory, immediately south of them. Using mitogenomes, we characterized two new D4h3a5 lineages almost exclusively associated with populations from Western Patagonia.DiscussionOur results contribute to the understanding of the peopling and human interactions in Western Patagonia, suggesting these unique maritime traditions developed within local populations, genetically associated with earlier terrestrial populations.

Albumin, oral contraceptives, and venous thromboembolism risk in astronauts.

A venous thromboembolism (VTE) event occurred in a female astronaut during long-duration spaceflight. Multiple factors may have contributed to this risk, including the use of combined (progestin + estrogen) oral contraceptives (cOC). Biochemistry data from 65 astronauts were evaluated for associations with cOC use and with sex. The female astronauts who used cOCs had lower concentrations of serum albumin and higher concentrations of transferrin, a protein involved in the clotting cascade, than the male astronauts and the female astronauts who were not taking cOCs (P < 0.001). The women who used cOCs had higher serum concentrations of the acute phase reactant ceruloplasmin and cortisol during flight (P < 0.001) than the men and the women who were not taking cOCs; they also had higher calculated whole blood viscosity than women not taking cOCs (P < 0.001). Lower circulating concentrations of albumin, higher concentrations of transferrin, and elevated markers of inflammation all could contribute to an increased risk of VTE during spaceflight. These changes, in association with a higher blood viscosity, can directly affect endothelial glycocalyx integrity and hypercoagulability status, both of which contribute to VTE risk in terrestrial populations.NEW & NOTEWORTHY We report here evidence of an association between oral contraceptive use and serum albumin, among other factors, which potentially increase the risk of venous thromboembolism in astronauts. These findings highlight potential risks to astronaut health while providing potential alternative countermeasures for decreasing VTE risk during spaceflight. These findings also highlight an underrecognized potential mechanism for hypoalbuminemia to increase VTE risk in terrestrial populations.

Preliminary investigation of effects of copper on a terrestrial population of the antarctic rotifer Philodina sp.

Terrestrial microinvertebrates in Antarctica are potentially exposed to contaminants due to the concentration of human activity on ice-free areas of the continent. As such, knowledge of the response of Antarctic microinvertebrates to contaminants is important to determine the extent of anthropogenic impacts. Antarctic Philodina sp. were extracted from soils and mosses at Casey station, East Antarctica and exposed to aqueous Cu for 96 h. The Philodina sp. was sensitive to excess Cu, with concentrations of 36 μg L−1 Cu (48 h) and 24 μg L−1 Cu (96 h) inhibiting activity by 50%. This is the first study to be published describing the ecotoxicologically derived sensitivity of a rotifer from a terrestrial population to metals, and an Antarctic rotifer to contaminants. It is also the first study to utilise bdelloid rotifer cryptobiosis (chemobiosis) as a sublethal ecotoxicological endpoint. This preliminary investigation highlights the need for further research into the responses of terrestrial Antarctic microinvertebrates to contaminants.

Seasonal Variation in Terrestrial Invertebrate Subsidies to Tropical Streams and Implications for the Feeding Ecology of Hart’s Rivulus (Anablepsoides hartii)

Terrestrial invertebrates are important subsidies to fish diets, though their seasonal dynamics and importance to tropical stream consumers are particularly understudied. In this year-round study of terrestrial invertebrate input to two Trinidadian headwater streams with different forest canopy densities, we sought to (a) measure the mass and composition of terrestrial inputs with fall-in traps to evaluate the influences of seasonality, canopy cover, and rainfall intensity, and; (b) compare terrestrial and benthic prey importance to Anablepsoides hartii (Hart’s Rivulus), the dominant invertivorous fish in these streams, by concurrently measuring benthic and drifting invertebrate standing stocks and the volume and composition of invertebrates in Rivulus guts throughout the year. The biomass of terrestrial invertebrate fall-in was 53% higher in the wet versus dry season; in particular, ant input was 320% higher. Ant biomass fall-in also increased with the density of canopy cover among sampling locations within both streams. Greater precipitation correlated with increased ant inputs to the more open-canopied stream and increased inputs of winged insects in the more closed canopy stream. Concurrently, the biomass of benthic invertebrates was reduced by more than half in the wet season in both streams. We detected no differences in the total volume of terrestrial prey in Rivulus diets between seasons, though ants were a greater proportion of their diet in the wet season. In contrast, benthic prey were nearly absent from Rivulus diets in the wet season in both streams. We conclude that terrestrial invertebrates are a substantial year-round prey subsidy for invertivores in tropical stream ecosystems like those we studied, which may contrast to most temperate streams where such terrestrial inputs are significantly reduced in the cold season. Interestingly, the strongest seasonal pattern in these tropical streams was observed in benthic invertebrate biomass which was greatly reduced and almost absent from Rivulus diets during the wet season. This pattern is essentially the inverse of the pattern observed in many temperate streams and highlights the need for additional studies in tropical ecosystems to better understand how spatial and temporal variation in terrestrial subsidies and benthic prey populations combine to influence consumer diets and the structure of tropical stream food webs.

Effects of Moderate Drought on Leaf Bulliform Cells of Aquatic and Coastal Population of Phragmites australis

Studying leaves of aquatic and terrestrial populations of Phragmites australis grown on the bank of the Venetian strait of the Dnipro River in Kyiv (Ukraine) for establishing the role of bulliform cells in the mechanisms of plant resistance to moderate soil drought were studied. Bulliform (motor) cells participate in the twisting and folding of leaves during drought and strong sunlight. The study of bulliform cells in the leaves of the aquatic and terrestrial populations of P. australis was carried out using the methods of light microscopy, cytochemical methods, laser confocal microscopy, and biochemical methods. The comparative analysis of the structure of bulliform cells of leaves of P. australis has shown significant differences depending on plant growth location. The differences in the number, size, and area of bulliform cells and also polysaccharide content showed clear phenotypical plasticity. Cytochemical and laser confocal microscopic studies of polysaccharides of cell walls in bulliform cells of aquatic and terrestrial ecotypes of P. australis showed that a decrease in soil moisture in a natural moderate drought of soil led to an increase in lignin and syringyl monolignol content in the outer walls of bulliform cells and also to a decrease in cellulose and callose content in outer and inner cell walls. The obtained data shows that the studied signs of bulliform cells can be markers of tolerance for population plants that have the ability to curl leaves for the preservation of optimal water balance in moderate drought.

Variation in morphological characters of Marsilea crenata living in floating aquatic, emergent aquatic, and terrestrial habitats

Abstract. Wisanti, Aloysius DC, Zubaidah S, Lestari SR. 2021. Variation in morphological characters of Marsilea crenata living in floating aquatic, emergent aquatic, and terrestrial habitats. Biodiversitas 22: 2853-2859. Marsilea is a hydrophyte fern that has plasticity often influenced by enviroment. Several of the species with different habitats or geographies show morphological variations. Therefore, this study aims to analyze the variations in morphological characters of M. crenata growing in aquatic and terrestrial habitats. A total of 38 plant samples were collected from their natural habitats including floating aquatic, emergent aquatic, and terrestrial types. Morphological variations data included 4 qualitative characters and 9 quantitative characters. The quantitative characters were analyzed by one-way ANOVA to test for differences, while the combination of both characters was analyzed using Principal Component Analysis (PCA) to determine the distribution between groups. The data results showed a separate grouping pattern between aquatic and terrestrial populations. These two groups showed significant differences in 5 quantitative characters and 2 qualitative characters. However, emergent aquatic samples’ distribution pattern is closer to the terrestrial group. The characters’ similarity of these two populations was in ??the rhizomes air spaces area, the position between leaflets and absence of red streak on the abaxial lamina. Conclusively, the variations in M. crenata’s morphological characters indicate that this plant has experienced morphological adaptations to water availability in its environment.

Revival and recent advancements in the spatial fishery models originally conceived by Sidney Holt and Ray Beverton

Abstract Sidney Holt and Ray Beverton are primarily recognized for developing the basis of demographic stock assessment modelling, but their enduring legacy continues to influence and guide advancements in many fields of fisheries science. Although largely forgotten, their contributions to spatial modelling laid the foundation for a variety of applications in aquatic and terrestrial populations. Spatial modelling approaches are rapidly evolving beyond even the visionary scope of Beverton and Holt due to advancements in understanding of spatial population structure, collection of spatially explicit data, and statistical parameter estimation. A review of Beverton and Holt’s original movement models demonstrates that understanding the origins and basic underlying assumptions can help ensure that current models are consistent with fundamental principles. Additionally, recent simulation studies show that conforming to or revising spatial model assumptions is essential for accurate estimation. As fisheries science transitions to more complex spatial stock assessment models, understanding their conceptual development and the lessons learned by our predecessors is essential for proper model specification and application.

Luticola rojkoviensis sp. nov. (Bacillariophyta), a new terrestrial diatom from Central Slovakia

Sampling of fungi in a grassland on a hill in Rojkov, Central Slovakia, revealed a new species of Luticola (Diadesmidaceae). Its terrestrial populations were found close to the basis of the fertile part of the geoglossoid fungi (Geoglossaceae) that were overgrown with filamentous cyanobacteria of the orders Oscillatoriales and Synechococcales. Luticola rojkoviensis sp. nov. is characterized by the valve outline and the structure of the external valve face: valves are weakly dorsiventrally asymmetrical, rhombic-lanceolate in larger cells to rhombic-elliptic and tri-undulate in smaller cells, with shortly protracted and broadly rounded valve apices. Valve face is minimally concave, as the axial area is lowered and the area around distal raphe elevated. The surface of the valve is mostly uneven due to many depressions, so the external shape of the areolae and the impression of irregular longitudinal rows depend on the extent of these valve ornamentations. Proximal raphe endings are unilaterally slightly deflected, expanded into small central pores. The shape of both the proximal and the distal raphe fissures is slightly asymmetrical. The morphological characteristics of Luticola rojkoviensis sp. nov. are remarkably similar to those of L. hustedtii Levkov, Metzeltin et A.Pavlov, L. ectorii Levkov, Metzeltin et A.Pavlov and L. acidoclinata Lange-Bertalot. The association of Luticola rojkoviensis sp. nov. with geoglossoid fungi and epiphytic cyanobacteria is discussed.

Inter- and intra-archipelago dynamics of population structure and gene flow in a Polynesian bird

Islands are separated by natural barriers that prevent gene flow between terrestrial populations and promote allopatric diversification. Birds in the South Pacific are an excellent model to explore the interplay between isolation and gene flow due to the region’s numerous archipelagos and well-characterized avian communities. The wattled honeyeater complex (Foulehaio spp.) comprises three allopatric species that are widespread and common across Fiji, Tonga, Samoa, and Wallis and Futuna. Here, we explored patterns of diversification within and among these lineages using genomic and morphometric data. We found support for three clades of Foulehaio corresponding to three recognized species. Within F. carunculatus, population genetic analyses identified nine major lineages, most of which were composed of sub-lineages that aligned nearly perfectly to individual island populations. Despite genetic structure and great geographic distance between populations, we found low levels of gene flow between populations in adjacent archipelagos. Additionally, body size of F. carunculatus varied randomly with respect to evolutionary history (as Ernst Mayr predicted), but correlated negatively with island size, consistent with the island rule. Our findings support a hypothesis that widespread taxa can show population structure between immediately adjacent islands, and likely represent many independent lineages loosely connected by gene flow.

Assessment of Eco-geomorphological potential of Mongolia

The eco-geomorphological analysis includes the impact assessment of relief under various ecosystem conditions in as much relief has various ecological roles, both direct and indirect. Rising elevation above sea level is mostly influenced by climate indirectly leading to reduced air pressure, oxygen deficiency, reduction of air temperature, excessive solar radiation, and creation of strong wind. The depth of relief dissection of the bumpy surface of mountainous areas created by floods and mudflows, and the depth of the bumpy surface increases energy consumption and poses risks during mountain climbing, and also has negative economic implications if economic activities are undertaken in such terrain. On the other hand, mountainous landscapes have a specific impact on human well-being and also have considerable potential for promoting tourism. Although, in the steppe environment, relief dissection increases the unique features of the landscape and increases the potential of tourism in other respects, however, it is assessed negatively to a large extent. The nature of corelationship between and the interdependence of the terrestrial surface and population, terrestrial surface and livestock, terrestrial surface and agriculture, which are significant in the study into the inter-relationship between environment and human society, was assessed and determined , and the relevant conclusion was drawn.

The effects of exposure to microgravity and reconditioning of the lumbar multifidus and anterolateral abdominal muscles: implications for people with LBP

One of the primary changes in the neuromuscular system in response to microgravity is skeletal muscle atrophy, which occurs especially in muscles that maintain posture while being upright on Earth. Reduced size of paraspinal and abdominal muscles has been documented after spaceflight. Exercises are undertaken on the International Space Station (ISS) during and following space flight to remediate these effects. Understanding the adaptations which occur in trunk muscles in response to microgravity could inform the development of specific countermeasures, which may have applications for people with conditions on Earth such as low back pain (LBP). The aim of this study was to examine the changes in muscle size and function of the lumbar multifidus (MF) and anterolateral abdominal muscles (1) in response to exposure to 6 months of microgravity on the ISS and (2) in response to a 15-day reconditioning program on Earth. Prospective longitudinal series. Data were collected from five astronauts who undertook seven long-duration missions on the ISS. For the MF muscle, measures included cross-sectional area (CSA) and linear measures to assess voluntary isometric contractions at vertebral levels L2 to L5. For the abdominal muscles, the thickness of the transversus abdominis (TrA), obliquus internus abdominis (IO) and obliquus externus abdominis (EO) muscles at rest and on contraction were measured. Ultrasound imaging of trunk muscles was conducted at four timepoints (preflight, postflight, mid-reconditioning, and post reconditioning). Data were analyzed using multilevel linear models to estimate the change in muscle parameters of interest across three time periods. Beta-coefficients (estimates of the expected change in the measure across the specified time period, adjusted for the baseline measurement) indicated that the CSA of the MF muscles decreased significantly at all lumbar vertebral levels (except L2) in response to exposure to microgravity (L3=12.6%; L4=6.1%, L5=10.3%; p<.001), and CSAs at L3-L5 vertebral levels increased in the reconditioning period (p<.001). The thickness of the TrA decreased by 34.1% (p<.017), IO decreased by 15.4% (p=.04), and the combination of anterolateral abdominal muscles decreased by 16.2% (p<.001) between pre- and postflight assessment and increased (TrA<0.008; combined p=.035) during the postreconditioning period. Results showed decreased contraction of the MF muscles at the L2 (from 12.8% to 3.4%; p=.007) and L3 (from 12.2% to 5%; p=.032) vertebral levels following exposure to microgravity which increased (L2, p=.046) after the postreconditioning period. Comparison with preflight measures indicated that there were no residual changes in muscle size and function after the postreconditioning period, apart from CSA of MF at L2, which remained 15.3% larger than preflight values (p<.001). In-flight exercise countermeasures mitigated, but did not completely prevent, changes in the size and function of the lumbar MF and anterolateral abdominal muscles. Many of the observed changes in size and control of the MF and abdominal muscles that occurred in response to prolonged exposure to microgravity paralleled those seen in people with LBP or exposed to prolonged bed rest on Earth. Daily individualized postflight reconditioning, which included both motor control training and weight-bearing exercises with an emphasis on retraining strength and endurance to re-establish normal postural alignment with respect to gravity, restored the decreased size and control of the MF (at the L3-L5 vertebral levels) and anterolateral abdominal muscles. Drawing parallels between changes which occur to the neuromuscular system in microgravity and which exercises best recover muscle size and function could help health professionals tailor improved interventions for terrestrial populations. Results suggested that the principles underpinning the exercises developed for astronauts following prolonged exposure to microgravity (emphasizing strength and endurance training to re-establish normal postural alignment and distribution of load with respect to gravity) can also be applied for people with chronic LBP, as the MF and anterolateral abdominal muscles were affected in similar ways in both populations. The results may also inform the development of new astronaut countermeasures targeting the MF and abdominal muscles.

Interplanetary transmissions of life in an evolutionary context

AbstractThe theory of lithopanspermia proposes the natural exchange of organisms between solar system bodies through meteorites. The focus of this theory comprises three distinct stages: planetary ejection, interplanetary transit and planetary entry. However, it is debatable whether organisms transported within the ejecta can survive all three stages. If the conjecture is granted, that life can indeed be safely transmitted from one world to another, then it is not only a topic pertaining to planetary science but also biological sciences. Hence, these stages are only the first three factors of the equation. The other factors for successful lithopanspermia are the quality, quantity and evolutionary strategy of the transmitted organisms. When expanding into new environments, invading organisms often do not survive in the first attempt and usually require several attempts through propagule pressure to obtain a foothold. There is a crucial difference between this terrestrial situation and the one brought about by lithopanspermia. While invasive species on Earth repeatedly enters a new habitat, a species pragmatically arrives on another solar system body only once; thus, an all-or-nothing response will be in effect. The species must survive in the first attempt, which limits the probability of survival. In addition, evolution sets a boundary through the existence of an inverse proportionality between the exchanges of life between two worlds, thus further restricting the probability of survival. However, terrestrial populations often encounter unpredictable and variable environmental conditions, which in turn necessitates an evolutionary response. Thus, one evolutionary mode in particular, bet hedging, is the evolutionary strategy that best smooth out this inverse proportionality. This is achieved by generating diversity even among a colony of genetically identical organisms. This variability in individual risk-taking increases the probability of survival and allows organisms to colonize more diverse environments. The present analysis to understand conditions relevant to a bacterial colony arriving in a new planetary environment provides a bridge between the theory of bet hedging, invasive range expansion and planetary science.