Pheromone trail following in the ant Lasius niger: high accuracy and variability but no effect of task state

The use of pheromone trails in ant colony organization is an important model for understanding collective decision‐making and complex adaptive systems. The ant Lasius niger L. (Hymenoptera: Fomicidae) is one of the main model organisms used for such studies. Key to understanding pheromone trail use by ants is knowing how well trails are followed. The results of a previous study suggest that L. niger trail following is poor, with between 60% and 70% accuracy at a T bifurcation. It is hypothesized that the true trail following accuracy is higher, and that the low accuracy reported previously is the result of a methodological error. Specifically, it is hypothesized that ‘task state’ (i.e. what the ants ‘thought they were doing’) affected pheromone following accuracy. In the present study, the task state of the ants is set experimentally to one of three states: scouting (completely naive), recruited (having information that food has been found, but not where it is) and shuttling (having a strong memory of the location of a food source). Trail following accuracy is tested for each group. Trail following is found to be more accurate than previously reported: 83%, 82% and 74% correct decisions for scouts, recruits and shuttlers, respectively. However, the difference between the three groups is not significant. Importantly, very high inter‐trial variation is reported both in the present study and in experiments from other research groups. This variation is unexplainable by trail strengths or colony‐level differences, and is highlighted as an important factor when experimentally measuring trail following.     

A new single nucleotide polymorphism in the rabbit (Oryctolagus cuniculus) myostatin (MSTN) gene is associated with carcass composition traits

This study aimed at the identification of genetic variations in the myostatin (MSTN) gene and testing their effects on carcass quality traits. We comparatively sequenced Giant Grey (GG) and New Zealand White (NZW) rabbits that were founders of a cross‐bred population. Alignment of our sequence data with the GenBank sequence of the rabbit MSTN gene (Ensembl Gene ID ENSOCUG00000012663) identified three single nucleotide polymorphisms (SNPs). The two novel SNPs (c.?125T>C, c.373+234G>A) and one known SNP (c.747+34C>T) were subsequently analysed for linkage with carcass composition traits in 363 F₂ animals of the cross GG × NZW. Significant linkage was found between c.373+234G>A and nine carcass composition traits (P < 0.05). No significant effects were found for c.?125T>C and c.747+34C>T. Because the linked SNP is located in intron 1 and no genetic variation was found in the coding region, further investigations are necessary to understand the functional effect of the c.373+234G>A variant on the variability of the traits.     

The contributions of programmed developmental change and phenotypic plasticity to within-individual variation in leaf traits in Dicerandra linearifolia

Variation among modules of a single genet could provide a means of adaptation to environmental heterogeneity. Two mechanisms that can give rise to such variation are programmed developmental change and phenotypic plasticity. I quantified the relative roles of these two mechanisms in causing within-individual variation in six leaf traits of an annual plant. Under controlled temperatures, morphological, anatomical, and physiological traits of leaves produced by the same individual differed as a function of both the node at which they were produced and the temperature they experienced during development. Temperature, node, and interactions between them all contributed significantly to the pattern of within-individual variation in leaf traits, although the relative contributions of programmed developmental change and phenotypic plasticity differed for different traits. I hypothesize that these two mechanisms for generating within-individual variation in module phenotype are favored by different patterns of environmental heterogeneity; when the sequence of environments encountered by modules of a single individual is predictable, programmed developmental change may be favored, and phenotypic plasticity may be favored when the sequence of environments is irregular with respect to individual ontogeny and therefore not predictable.     

Reproduction of the rare monocarpic species Saxifraga mutata L.

The aim of the study is to investigate the impact of reproduction and genetic variation on the persistence of populations of the prealpine, monocarpic Saxifraga mutata L. The species grows on erosion slopes or rocks, and its local populations are often small and isolated. Crossing experiments resulted in better seed-set than selfing, but both yielded viable seeds. Agamospermy did not occur. In an early-successional species like S. mutata , successful selfing is important in the colonization of new habitats. Flowers of S. mutata were visited by Syrphidae and unspecialized Hymenoptera. A germination rate of 40% was reached in cultivation after 20 weeks but germination continued until the end of the experiment after 92 weeks. Seeds stored dry for 30 months at room temperature mostly lost their germinability. In natural habitats, seedlings were found almost throughout the year with a peak in spring. Suitable safe sites were small patches of open soil, bare marl on erosion slopes, and rock crevices. AU individuals investigated were diploid with 2n = 26. Allozyme electrophoresis showed a lack of segregation within the populations. Intra- and interpopulation genetic variation was low. These results were in partial disagreement with theoretical expectations in a mixed mating species. It is concluded that demographic rather than genetic processes are the main cause of extinction of populations of S. mutata , at least in the short-term.     

Genetic Characteristics of Restored Elk Populations in Kentucky

Translocations are a common management practice to restore or augment populations. Understanding the genetic consequences of translocation efforts is important for the long-term health of restored populations. The restoration of elk (Cervus canadensis) to Kentucky, USA, included source stocks from 6 western states, which were released at 8 sites in southeastern Kentucky during 1997–2002. We assessed genetic diversity in restored herds and compared genetic similarity to source stocks based on 15 microsatellite DNA loci. Genetic variation in the restored populations was comparable to source stocks ( allelic richness = 3.52 and 3.50; expected heterozygosity = 0.665 and 0.661 for restored and source, respectively). Genetic differentiation among all source and restored populations ranged from 0.000 to 0.065 for pairwise F_ST and 0.034 to 0.161 for pairwise Nei's D_A. Pairwise genetic differentiation and Bayesian clustering revealed that stocks from Utah and North Dakota, USA, contributed most to restored populations. Other western stocks appeared less successful and were not detected with our data, though our sampling was not exhaustive. We also inferred natural movements of elk among release sites by the presence of multiple genetic stocks. The success of the elk restoration effort in Kentucky may be due, in part, to the large number of elk (n = 1,548), repeated releases, and use of diverse source stocks. Future restoration efforts for elk in the eastern United States should consider the use of multiple stock sources and a large number of individuals. In addition, preservation of genetic samples of founder stock will enable detailed monitoring in the future. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Seasonal and Diel Changes in Behaviour,Microhabitat use and Preferences by Young Pool-dwelling Atlantic Salmon,Salmo salar,and Brown Trout,Salmo trutta

There was a pronounced decline in activity of young pool-dwelling Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, as the water temperatures dropped in the autumn and early winter, and the fish switched from a predominantly diurnal towards a nocturnal activity pattern. Such a switch in activity pattern has previously been observed in young brown trout, but the present study is the first documentation for juvenile Atlantic salmon under natural conditions. Juvenile fish fed actively even when water temperatures were below 0°C, although foraging behaviour at near-freezing temperatures was recorded exclusively during night surveys. This indicates that other proximate factors, in addition to water temperature, affect the activity of young salmon and trout in rivers. Trout kept feeding positions significantly higher above bottom than salmon in August and September, but both species reduced the height above bottom at the onset of winter, possibly due to reduced swimming performance and lowered food availability in the upper part of the water column.     

Comparison of Southern Appalachian high-elevation outcrop plant communities with their Northern Appalachian counterparts

Abstract. Southern Appalachian high-elevation outcrops harbour six regionally rare Northern Appalachian taxa usually considered relicts of a Pleistocene alpine flora. For five of the six taxa, minimum elevation in the south was 367–1113 m higher than in the north. While habitats compared between the two regions share only 9% of their total flora, individual plots had up to 70% of their species occurring in the opposite region. The northern affinity of southern outcrops increased with elevation, slope steepness, soil Cu, B and SO₄ and decreased with potential solar radiation and soil Na. As a result, communities above 1600 m on felsic bedrock, and above 1350 m on mafic bedrock, were most northern in composition. Northern affinity of southern outcrops also increased with latitude, which may partly result from closer geographic proximity to past communities that provided progenitors for the current northern flora. Northern treeless habitats increased in southern affinity with increased slope steepness, perennial seepage, vegetation height, shade, soil pH, Al, Mn, Na and decreased elevation and organic matter. As a result, northern outcrop communities below treeline were most similar to those on southern outcrops. This suggests that southern outcrop vegetation may be more similar to Pleistocene outcrop vegetation than to Pleistocene alpine vegetation. Partial constrained ordination showed that while compositional differences between the Northern and Southern Appalachian habitats were largely explained by environmental differences, there was a significant component of residual variation explained by north or south position that was unrelated to environment. These residual compositional differences may result from historical influences on community structure involving stochastic extinction and colonization processes.