Fine-scale spatial population patterns and mobility of winter-annual herbs in a dry grassland

Abstract. Winter annuals were mapped in a series of permanent plots located in gaps in an Austrian dry grassland over a period of 3 yr. Great differences in abundance were found among nine winter annuals — Arabis auriculata, Arenaria leptoclados, Cerastium glutinosum, Erophila spathulata, Holosteum umbellatum, Hornungia petraea, Saxifraga tridactylites, Thlaspi perfoliatum and Veronica praecox –- occurring in the gaps. The absolute frequency of species varied considerably from year to year, while their relative proportions remained nearly constant in the plots over the study period. High spatial dissociation (low level of spatial coincidence) between populations was observed; this was ascribed to boleochory, known to generate monospecific patches. No trend in self-replacement of a species was found. This means that occupying a place in one year does not necessarily mean the same place will be occupied in following years. The probability of a species replacing another was found to be low. The space could be inhabited by any species or remain unoccupied. We suggest that the distribution patterns of species are controlled by dispersal and preference for microhabitats, at least at the scale of 20 cm × 20 cm. It was shown by a permutation method based on cumulative frequencies, that at smaller scales the habitat differentiation vanishes. We suggest that, up to a typical dispersal range of the winter annuals, the Carousel model can be applied due to the lack of coincidence (and presumably also interactions) of individuals. Nevertheless, time may eliminate the habitat differentiation at any scale. A design of an improved data-sampling and a handling procedure was developed.     

A protein sequence fitness function for identifying natural and nonnatural proteins

The infinitesimally small sequence space naturally scouted in the millions of years of evolution suggests that the natural proteins are constrained by some functional prerequisites and should differ from randomly generated sequences. We have developed a protein sequence fitness scoring function that implements sequence and corresponding secondary structural information at tripeptide levels to differentiate natural and nonnatural proteins. The proposed fitness function is extensively validated on a dataset of about 210 000 natural and nonnatural protein sequences and benchmarked with existing methods for differentiating natural and nonnatural proteins. The high sensitivity, specificity, and percentage accuracy (0.81%, 0.95%, and 91% respectively) of the fitness function demonstrates its potential application for sampling the protein sequences with higher probability of mimicking natural proteins. Moreover, the four major classes of proteins (α proteins, β proteins, α/β proteins, and α + β proteins) are separately analyzed and β proteins are found to score slightly lower as compared to other classes. Further, an analysis of about 250 designed proteins (adopted from previously reported cases) helped to define the boundaries for sampling the ideal protein sequences. The protein sequence characterization aided by the proposed fitness function could facilitate the exploration of new perspectives in the design of novel functional proteins.     

Attraction range of a sex pheromone trap for the damson‐hop aphid Phorodon humuli (Hemiptera: Aphididae)

The attraction range of olfactory response by winged female gynoparae (autumn migrants that give birth to oviparae, the sexual females) and male damson–hop aphids Phorodon humuli (Schrank) is investigated in field experiments over 2 years by analyzing the spatial patterns of catches in concentric circles of yellow‐painted traps (60 in total) around a central trap releasing the species' sex pheromone, (1RS,7S,7aS)‐nepetalactol. Males are more likely than females to be found in the central trap, with 65.6% of the 1824 males caught there compared with 11.2% of 1346 females. Both morphs are more numerous in traps axial with the mean wind direction and centred on the pheromone‐release trap than at other angles. Males are approximately five‐fold more numerous in traps downwind than at similar distances upwind of the pheromone, showing that its presence stimulates landing. For males, the estimated active space of the lure extends 6 m downwind. Catches of females are equally numerous up and downwind of the pheromone lure because females orienting on the axis of the pheromone source continue to respond to visual cues in their flight path if they overshoot the olfactory one. For females, the active space of a pheromone lure is less than 2 m downwind. It is unimportant for either morph whether the pheromone‐release trap is yellow or transparent. In these experiments, both morphs orient with, track and probably arrive in the pheromone source trap from at least 26 m, the distance to the nearest aphid‐infested hops.     

Habitat Selection by Female Elk During Minnesota's Agricultural Season

Understanding space-use patterns by elk (Cervus canadensis) is essential to alleviating human-elk conflicts, particularly when crop depredation by elk can make it harder to justify to the public the need to restore elk populations to regions with agricultural landscapes. In 2016–2017, we used global positioning system data from 20 female elk to investigate their selection for agricultural cover during the agricultural season (1 May–31 Oct) in northwestern Minnesota, USA. We estimated resource selection functions with resource availability defined at the home range scale. Elk space use was primarily determined by distance to forest cover in areas proximate to agricultural fields. During diurnal periods, elk selected areas with forest cover near agricultural fields planted with legumes and cereal. During nocturnal periods, elk selected for agricultural fields with little to no canopy and that were planted with legumes. We suggest that management of elk in northwestern Minnesota will require practices that discourage the use of agriculture by elk while improving natural habitats within areas managed for elk restoration. We suggest that forestry practices (i.e., thinning and burning) could improve cover and forage openings for elk in restoration areas. Furthermore, managers could work with agricultural producers where elk occur to plant crops favored by elk (i.e., legumes) outside known home ranges and plant fields within home ranges with crops that elk avoided (i.e., hay). Collectively, these practices may shift the ranges of elk herds into restoration areas and lower conflict between the public and elk restoration efforts. © 2020 The Wildlife Society.     

Spatial information analysis of chemotactic trajectories

During bacterial chemotaxis, a cell acquires information about its environment by sampling changes in the local concentration of a chemoattractant, and then uses that information to bias its motion relative to the source of the chemoattractant. The trajectory of a chemotaxing bacteria is thus a spatial manifestation of the information gathered by the cell. Here we show that a recently developed approach for computing spatial information using Fourier coefficient probabilities, the k-space information (kSI), can be used to quantify the information in such trajectories. The kSI is shown to capture expected responses to gradients of a chemoattractant. We then extend the k-space approach by developing an experimental probability distribution (EPD) that is computed from chemotactic trajectories collected under a reference condition. The EPD accounts for connectivity and other constraints that the nature of the trajectories imposes on the k-space computation. The EPD is used to compute the spatial information from any trajectory of interest, relative to the reference condition. The EPD-based spatial information also captures the expected responses to gradients of a chemoattractant, although the results differ in significant ways from the original kSI computation. In addition, the entropy calculated from the EPD provides a useful measure of trajectory space. The methods developed are highly general, and can be applied to a wide range of other trajectory types as well as non-trajectory data.     

Gut microbiome and human health under the space environment

The gut microbiome is well recognized to have a pivotal role in regulation of the health and behaviour of the host, affecting digestion, metabolism, immunity, and has been linked to changes in bones, muscles and the brain, to name a few. However, the impact of microgravity environment on gut bacteria is not well understood. In space environments, astronauts face several health issues including stress, high iron diet, radiation and being in a closed system during extended space missions. Herein, we discuss the role of gut bacteria in the space environment, in relation to factors such as microgravity, radiation and diet. Gut bacteria may exact their effects by synthesis of molecules, their absorption, and through physiological effects on the host. Moreover we deliberate the role of these challenges in the dysbiosis of the human microbiota and possible dysregulation of the immune system.