Landscape characteristics influencing the genetic structure of greater sage‐grouse within the stronghold of their range: a holistic modeling approach

Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high‐ and low‐quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage‐grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low‐quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33‐km‐diameter moving windows were preferred, suggesting small‐scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape on gene flow.     

Genetic polymorphism in dopamine receptor D4 is associated with early body condition in a large population of greater flamingos, Phoenicopterus roseus

Body condition is an important determinant of fitness in many natural populations. However, as for many fitness traits, the underlying genes that regulate body condition remain elusive. The dopamine receptor D4 gene (DRD4) is a promising candidate as dopamine is known to play an important role in the regulation of food intake and the metabolism of both glucose and lipids in vertebrates. In this study, we take advantage of a large data set of greater flamingos, Phoenicopterus roseus, to test whether DRD4 polymorphism predicts early body condition (EBC) while controlling for whole-genome effects of inbreeding and outbreeding using microsatellite multilocus heterozygosity (MLH). We typed 670 of these individuals for exon 3 of the homologue of the human DRD4 gene and 10 microsatellite markers. When controlling for the effects of yearly environmental variations and differences between sexes, we found strong evidence of an association between exon 3 DRD4 polymorphisms and EBC, with 2.2-2.3% of the variation being explained by DRD4 polymorphism, whereas there was only weak evidence that MLH predicts EBC. Because EBC is most likely a polygenic trait, this is a considerable amount of variation explained by a single gene. This is to our knowledge, the first study to show an association between exon 3 DRD4 polymorphism and body condition in non-human animals. We anticipate that the DRD4 gene as well as other genes coding for neurotransmitters and their receptors may play an important role in explaining variation in traits that affect fitness.     

Recovery of Greater Sage-Grouse Habitat Features in Wyoming Big Sagebrush following Prescribed Fire

The ability of prescribed fire to enhance habitat features for Greater Sage-Grouse ( Centrocercus urophasianus ) in Wyoming big sagebrush ( Artemisia tridentata wyomingensis ) in western North America is poorly understood. We evaluated recovery of habitat features important to wintering, nesting, and early brood-rearing Sage-Grouse in Wyoming big sagebrush following prescribed fire. Our case study included 1 year of preburn (1989) and 10 years of postburn data collected over 14 years (1990–2003) from control and burned study areas in the Big Desert of southeastern Idaho, U.S.A. We compared recovery and rate of change for 12 features in four categories between burned and control transects and recovery in burned transects including change in variation. Our results indicate that prescribed fire induced quantifiable changes in wintering, nesting, and early brood-rearing Sage-Grouse habitat features 14 years after fire in Wyoming big sagebrush in our study area. Specifically, grass and litter required by Sage-Grouse for nest and brood concealment recovered relatively rapidly following fire; major forb cover was similar between burned and control sites, but the rate of increase for major forb cover and richness was greater in control transects, and structurally mediated habitat features required by Sage-Grouse for food and cover in winter and for nest and brood concealment in spring recovered slowly following fire. Because shrub structural features in our study did not recover in magnitude or variability to preburn levels 14 years after fire, we recommend that managers avoid burning Wyoming big sagebrush to enhance Sage-Grouse habitat, but rather implement carefully planned treatments that maintain Sagebrush.     

Effects of photoperiod,mineral medium strength,inorganic ammonium,sucrose and cytokinin on root,shoot and microtuber development in shoot cultures of Dioscorea alata L. and D. bulbifera L. yams

The effects of photoperiod (8, 12 or 16 h), mineral medium strength (dilutions of a tuberization medium, the T medium), sucrose (0, 2, 4, 8% w/v) and kinetin (0, 2.5μM) on the development of roots, shoots and microtubers in shoot cultures of Dioscorea alata L. and D. bulbifera L. yams were evaluated. All of the factors were found to have substantial effects on microtuber induction in these two species. The effects of high and low inorganic ammonium containing media on microtuberization of yam shoot cultures indicated that ammonium ions inhibited microtuber induction in D. alata but not in D. bulbifera. Microtubers of D. alata were only formed on shoot cultures if these were held under 8-h days. D. bulbifera cultures on the other hand produced microtubers under this photoperiod treatment as well as under 16-h photoperiods provided that kinetin was present in media at 2.5μM. Most microtuberization in D. alata shoot cultures occurred on full-strength T medium supplemented with 2% sucrose, 2.5μM kinetin held under 8-h photoperiod at 25°C, whereas most microtuberization in D. bulbifera shoot cultures occurred on full-strength MS medium supplemented with 4% sucrose, 2.5μM kinetin held under 8-h photoperiods at 25°C. Under these two sets of conditions, yam shoot cultures consistently produced microtubers with individual weights in excess of 100 mg which were large enough to be capable of direct planting and subsequent growth in unsterilized soils.     

Response of greater sage-grouse to sagebrush reduction treatments in Wyoming big sagebrush

Vegetation treatments have been widely implemented in efforts to enhance conditions for wildlife populations. Yet the effectiveness of such efforts often lack rigorous evaluations to determine whether these practices are effective for targeted species. This is particularly important when manipulating wildlife habitats in ecosystems that are faced with multiple stressors. The sagebrush (Artemisia spp.) ecosystem has been altered extensively over the last century leading to declines of many associated species. Wyoming big sagebrush (A. tridentata wyomingensis) is the most widely distributed subspecies, providing important habitats for sagebrush-obligate and associated wildlife. Sagebrush often has been treated with chemicals, mechanical treatments, and prescribed burning to increase herbaceous forage species released from competition with sagebrush overstory. Despite many studies documenting negative effects of sagebrush control on greater sage-grouse (Centrocercus urophasianus) habitat, treatments are still proposed as a means of improving habitat for sage-grouse and other sagebrush-dependent species. Furthermore, most studies have focused on vegetation response and none have rigorously evaluated the direct influence of these treatments on sage-grouse. We initiated a 9-year (2011–2019) experimental study in central Wyoming, USA, to better understand how greater sage-grouse respond to sagebrush reduction treatments in Wyoming big sagebrush communities. We evaluated the influence of 2 common sagebrush treatments on greater sage-grouse demography and resource selection. We implemented mowing and tebuthiuron application in winter and spring 2014 and evaluated the pre- (2011–2013) and post-treatment (2014–2019) responses of sage-grouse relative to these management actions. We evaluated responses to treatments using demographic and behavioral data collected from 620 radio-marked female greater sage-grouse. Our specific objectives were to evaluate how treatments influenced 1) sage-grouse reproductive success and female survival; 2) sage-grouse nesting, brood-rearing, and female resource selection; 3) vegetation responses; and 4) forbs and invertebrates. Our results generally suggested neutral demographic responses and slight avoidance by greater sage-grouse in response to Wyoming big sagebrush treated by mowing and tebuthiuron. Neither mowing nor tebuthiuron treatments influenced nest survival, brood survival, or female survival. Selection for nest and brood-rearing sites did not differ before and after treatments. Females selected habitats near treatments before and after they were implemented; however, the strength of selection was lower after treatments compared with pre-treatment periods, which may be explained by a lack of response in vegetation and invertebrates following treatments. Perennial grass cover and height varied temporally yet did not vary systematically between treatment and control plots. Forb cover and species richness varied annually but not in relation to either treatment type. Perennial grass cover and height, forb cover, and forb species richness did not increase within mowed or tebuthiuron-treated areas that received 2 or 6 years of grazing rest compared with areas that received no grazing rest. Finally, forb and invertebrate dry mass did not differ between treated plots and control plots at mowing or tebuthiuron sites in any years following treatments. Results from our study add to a large body of evidence that sage-grouse using Wyoming big sagebrush vegetation communities do not respond positively to sagebrush manipulation treatments. Management practices that focus on the maintenance of large, undisturbed tracts of sagebrush will best facilitate the persistence of sage-grouse populations and other species reliant on the sagebrush steppe.     

Circadian self-feeding rhythms in greater amberjack Seriola dumerili (Risso)

In the present study, 10 greater amberjack Seriola dumerili held individually were given free access to self-feeder, and trigger actuations were continuously monitored. Most (80%) of greater amberjack developed stable self-feeding activity within 1 week. The fish was a rigidly diurnal feeder under a 12L:12D cycle, with a feeding peak of 1–3 h occurring just after the onset of lights. Under constant conditions, all 10 individual fish exhibited free-running self-feeding rhythms, which persisted for 43 days without a sign of damping out. As far as is known, this seems to be the longest record of free-running behavioural rhythms in fishes. Except one fish free-ran at a period length (τ) of 25·2 h, τ of free-running self-feeding rhythms in the other nine fish was shorter than 24 h, ranging from 20·0 h to 21·5 h. In addition, phase transients of feeding activity were observed in response to the advancement of lights on. It is concluded that feeding activity in greater amberjack is mediated by endogenous circadian oscillators.     

Development and tissue origins of the mammalian cranial base

The vertebrate cranial base is a complex structure composed of bone, cartilage and other connective tissues underlying the brain; it is intimately connected with development of the face and cranial vault. Despite its central importance in craniofacial development, morphogenesis and tissue origins of the cranial base have not been studied in detail in the mouse, an important model organism. We describe here the location and time of appearance of the cartilages of the chondrocranium. We also examine the tissue origins of the mouse cranial base using a neural crest cell lineage cell marker, Wnt1-Cre/R26R, and a mesoderm lineage cell marker, Mesp1-Cre/R26R. The chondrocranium develops between E11 and E16 in the mouse, beginning with development of the caudal (occipital) chondrocranium, followed by chondrogenesis rostrally to form the nasal capsule, and finally fusion of these two parts via the midline central stem and the lateral struts of the vault cartilages. X-Gal staining of transgenic mice from E8.0 to 10 days post-natal showed that neural crest cells contribute to all of the cartilages that form the ethmoid, presphenoid, and basisphenoid bones with the exception of the hypochiasmatic cartilages. The basioccipital bone and non-squamous parts of the temporal bones are mesoderm derived. Therefore the prechordal head is mostly composed of neural crest-derived tissues, as predicted by the New Head Hypothesis. However, the anterior location of the mesoderm-derived hypochiasmatic cartilages, which are closely linked with the extra-ocular muscles, suggests that some tissues associated with the visual apparatus may have evolved independently of the rest of the “New Head”.     

Microsatellite loci for the greater horseshoe bat,Rhinolophus ferrumequinum (Rhinolophidae,Chiroptera) and their cross‐utility in 17 other bat species

We have isolated 14 polymorphic greater horseshoe bat, Rhinolophus ferrumequinum microsatellite loci. The number of alleles varied from two to 12 in 58 individuals. These loci will be used to assign paternity in order to characterize patterns of breeding and reproductive success in a wild R. ferrumequinum population. Loci were also tested in 17 other bat species. Twelve loci cross‐amplified in other species and three loci were polymorphic in all eight Rhinolophus species tested.