Culex erraticus (Diptera: Culicidae) utilizes gopher tortoise burrows for overwintering in North Central Florida.

Mosquito-borne diseases represent a significant threat to human and animal health in the United States. Several viruses, including West Nile, Saint Louis encephalitis, and Eastern equine encephalitis are endemic. In humans, the disease is typically detected during the summer months, but not during the winter months. The ability of these viruses to reemerge year after year is still not fully understood, but typically involves persistence in a reservoir host or vector during periods of low transmission. Mosquito species are known to overwinter at different life stages (adults, larvae, or eggs) in manufactured or natural sites. Gopher tortoise burrows are known to serve as refuge for many vertebrate and invertebrate species in pine savannas. In this study, we surveyed the interior of gopher tortoise burrows for overwintering mosquitoes. We identified 4 species (Anopheles crucians s.l., Culex erraticus, Mansonia dyari, and Uranotaenia sapphirina). Cx. erraticus was the most abundant, and its presence and abundance increased in winter months, implying that this species utilized gopher tortoise burrows for overwintering. Bloodfed Cx. erraticus and An. crucians s.l. females were detected. While An. crucians s.l. fed exclusively on the white-tailed deer, Cx. erraticus had a more diverse host range but fed primarily on the gopher tortoise. Tortoises and other long-lived reptiles like the American alligator have been shown to sustain high viremia following West Nile virus (WNV) and Eastern equine encephalitis virus (EEEV) infection and therefore could play a role in the maintenance of these viruses. In addition, Cx. erraticus is naturally infected with WNV and is a known bridge vector for EEEV. As such, these overwintering sites may play a role in perpetuating over-winter arboviral activity in Florida.

Food deprivation reduces sensitivity of liver Igf1 synthesis pathways to growth hormone in juvenile gopher rockfish (Sebastes carnatus).

Growth hormone (Gh) regulates growth in part by stimulating the liver to synthesize and release insulin-like growth factor-1 (Igf1), which then promotes somatic growth. However, for fish experiencing food limitation, elevated blood Gh can occur even with low circulating Igf1 and slow growth, suggesting that nutritional stress can alter the sensitivity of liver Igf1 synthesis pathways to Gh. Here, we examined how recent feeding experience affected Gh regulation of liver Igf1 synthesis pathways in juvenile gopher rockfish (Sebastes carnatus) to illuminate mechanisms underlying the nutritional modulation of Igf1 production. Juvenile gopher rockfish were maintained under conditions of feeding or complete food deprivation (fasting) for 14 d and then treated with recombinant sea bream (Sparus aurata) Gh or saline control. Gh upregulated hepatic igf1 mRNA levels in fed fish but not in fasted fish. The liver of fasted rockfish also showed a lower relative abundance of gene transcripts encoding teleost Gh receptors 1 (ghr1) and 2 (ghr2), as well as reduced protein levels of phosphorylated janus tyrosine kinase 2 (pJak2) and signal transducer and activator of transcription 5 (pStat5), which function to induce igf1 gene transcription following Gh binding to Gh receptors. Relative hepatic mRNA levels for suppressors of cytokine signaling (Socs) genes socs2, socs3a, and socs3b were also lower in fasted rockfish. Socs2 can suppress Gh activation of Jak2/Stat5, and fasting-related variation in socs expression may reflect modulated inhibitory control of igf1 gene transcription. Fasted rockfish also had elevated liver mRNA abundances for lipolytic hormone-sensitive lipase 1 (hsl1) and Igf binding proteins igfbp1a, -1b and -3a, reduced liver mRNAs encoding igfbp2b and an Igfbp acid labile subunit-like (igfals) gene, and higher transcript abundances for Igf1 receptors igf1ra and igf1rb in skeletal muscle. Together, these findings suggest that food deprivation impacts liver Igf1 responsiveness to Gh via multiple mechanisms that include a downregulation of hepatic Gh receptors, modulation of the intracellular Jak2/Stat5 transduction pathway, and possible shifts in Socs-inhibitory control of igf1 gene transcription, while also demonstrating that these changes occur in concert with shifts in liver Igfbp expression and muscle Gh/Igf1 signaling pathway components.

Nutritional status affects Igf1 regulation of skeletal muscle myogenesis, myostatin, and myofibrillar protein degradation pathways in gopher rockfish (Sebastes carnatus).

Insulin-like growth factor-1 (Igf1) regulates skeletal muscle growth in fishes by increasing protein synthesis and promoting muscle hypertrophy. When fish experience periods of insufficient food intake, they undergo slower muscle growth or even muscle wasting, and those changes emerge in part from nutritional modulation of Igf1 signaling. Here, we examined how food deprivation (fasting) affects Igf1 regulation of liver and skeletal muscle gene expression in gopher rockfish (Sebastes carnatus), a nearshore rockfish of importance for commercial and recreational fisheries in the northeastern Pacific Ocean, to understand how food limitation impacts Igf regulation of muscle growth pathways. Rockfish were either fed or fasted for 14 d, after which a subset of fish from each group was treated with recombinant Igf1 from sea bream (Sparus aurata). Fish that were fasted lost body mass and had lower body condition, reduced hepatosomatic index, and lower plasma Igf1 concentrations, as well as a decreased abundance of igf1 gene transcripts in the liver, increased hepatic mRNAs for Igf binding proteins igfbp1a, igfbp1b, and igfbp3a, and decreased mRNA abundances for igfbp2b and a putative Igf acid labile subunit (igfals) gene. In skeletal muscle, fasted fish showed a reduced abundance of intramuscular igf1 mRNAs but elevated gene transcripts encoding Igf1 receptors A (igf1ra) and B (igf1rb), which also showed downregulation by Igf1. Fasting increased skeletal muscle mRNAs for myogenin and myostatin1, as well as ubiquitin ligase F-box only protein 32 (fbxo32) and muscle RING-finger protein-1 (murf1) genes involved in muscle atrophy, while concurrently downregulating mRNAs for myoblast determination protein 2 (myod2), myostatin2, and myogenic factors 5 (myf5) and 6 (myf6 encoding Mrf4). Treatment with Igf1 downregulated muscle myostatin1 and fbxo32 under both feeding conditions, but showed feeding-dependent effects on murf1, myf5, and myf6/Mrf4 gene expression indicating that Igf1 effects on muscle growth and atrophy pathways is contingent on recent food consumption experience.

The earliest dipodomyine heteromyid in North America and the phylogenetic relationships of geomorph rodents.

Dipodomyine heteromyids (kangaroo rats and mice) are a diverse group of arid-adapted ricochetal rodents of North America. Here, a new genus and species of a large dipodomyine is reported from early Miocene-aged deposits of the John Day Formation in Oregon that represents the earliest record of the subfamily. The taxon is known from a single specimen consisting of a nearly complete skull, dentary, partial pes, and caudal vertebra. The specimen is characterized by a mosaic of ancestral and highly derived cranial features of heteromyids. Specifically, the dental morphology and some cranial characteristics are similar to early heteromyids, but other aspects of morphology, including the exceptionally inflated auditory bullae, are more similar to known dipodomyines. This specimen was included in a phylogenetic analysis comprising 96 characters and the broadest sampling of living and extinct geomorph rodents of any morphological phylogenetic analysis to date. Results support the monophyly of crown-group Heteromyidae exclusive of Geomyidae and place the new taxon within Dipodomyinae. The new heteromyid is the largest known member of the family. Analyses suggest that large body size evolved several times within Heteromyidae. Overall, the morphology of the new heteromyid supports a mosaic evolution of the open-habitat adaptations that characterize kangaroo rats and mice, with the inflation of the auditory bulla appearing early in the group, and bipedality/ricochetal locomotion appearing later. We hypothesize that cooling and drying conditions in the late Oligocene and early Miocene favored adaptations for life in more open habitats, resulting in increased locomotor specialization in this lineage over time from a terrestrial ancestor.

Incipient morphological specializations associated with fossorial life in the skull of ground squirrels (Sciuridae, Rodentia).

Anatomical and biological specializations have been studied extensively in fossorial rodents, especially in subterranean species, such as mole-rats or pocket-gophers. Sciurids (i.e., squirrels) are mostly known for their diverse locomotory behaviors, and encompass many arboreal species. They also include less specialized fossorial species, such as ground squirrels that are mainly scratch diggers. The skull of ground squirrels remains poorly investigated in a fossorial context, while it may reflect incipient morphological specializations associated with fossorial life, especially due to the putative use of incisors for digging in some taxa. Here, we present the results of a comparative analysis of the skull of five fossorial sciurid species, and compare those to four arboreal sciurids, one arboreal/fossorial sciurid and one specialized fossorial aplodontiid. The quantification of both cranial and mandibular shapes, using three dimensional geometric morphometrics, reveals that fossorial species clearly depart from arboreal species. Fossorial species from the Marmotini tribe, and also Xerini to a lesser extent, show widened zygomatic arches and occipital plate on the cranium, and a wide mandible with reduced condyles. These shared characteristics, which are present in the aplodontiid species, likely represent fossorial specializations rather than relaxed selection on traits related to the ancestral arboreal condition of sciurids. Such cranial and mandibular configurations combined with proodont incisors might also be related to the frequent use of incisors for digging (added to forelimbs), especially in Marmotini evolving in soft to hard soil conditions. This study provides some clues to understand the evolutionary mechanisms shaping the skull of fossorial rodents, in relation to the time spent underground and to the nature of the soil.

Male gopher tortoise (Gopherus polyphemus) concentration-dependent social responses to diluted mental gland pheromones.

In complex terrestrial environments, chemical signals can be the most important sensory modality for locating conspecifics for potential mating opportunities, especially in spatially segregated populations or habitats. Organisms must evolve chemical signals to maximize the efficacy of conveying information, particularly in creating trails or mate-choice cues. Long-distance transmission of chemical signals may be an increasingly important management concern for small and fractured populations or potentially threatened species, such as gopher tortoises in the southeastern U.S. Mental gland secretions have been shown to have pheromonal function in gopher tortoises, suggesting a potential role as trail or marking pheromones, allowing males to track females or other males to find females. In this study, male gopher tortoises were given paired presentations of a negative control (distilled water) with serial dilutions (1:4, 1:20, 1:100, and 1:500) of male mental gland secretions. Male tortoises were able to discern treatment differences up to 1:20 diluted secretions, responding with an array of social behaviors (e.g. for the 1:20 dilution trial, carapace alignment and head bobbing occurred more frequently for the mental gland secretion relative to the control; p < 0.01). Multivariate principal components analysis yielded PC1 (including, approach, carapace alignment, head bobbing, tasting air, sniffing, and doubleback) that differed by treatment (p = 0.0007) and also was higher for the 1:20 diluted presentation relative to the 1:500 diluted presentation (p = 0.04). This study provides insight into gopher tortoise ecology, mate-choice, and the utility of environmentally diluted mental gland secretions in the external environment when seeking mating opportunities.

Root cropping by pocket gophers.

Pocket gophers (Geomys spp.) are solitary, root-eating fossorial rodents native to North and Central American grasslands and are presumed to acquire most of their food through excavation of tunnels maintained as part of tunnel systems up to 160 m long1,2. Given that burrowing is 360-3,400 times more energetically costly than surface walking, pocket gophers have high energy requirements3. Roots are scarce at the depths of their tunnels in the sandy soil of our study site (20-64 cm), but here we describe a novel food source for southeastern pocket gophers (Geomys pinetis, hereafter gophers): roots that grow into their tunnels. These roots could supply an average of 21% but up to 62% of their daily basal energetic needs.

A comparison of non-surgical methods for sexing young gopher tortoises (Gopherus polyphemus).

Many turtle species have temperature-dependent sex determination (TSD), raising the prospect that climate change could impact population dynamics by altering sex ratios. Understanding how climate change will affect populations of animals with TSD requires a reliable and minimally invasive method of identifying the sexes of young individuals. This determination is challenging in many turtles, which often lack conspicuous external sexual dimorphism until years after hatching. Here, we explore four alternatives for sexing three age classes of captive-reared young gopher tortoises (Gopherus polyphemus), a terrestrial turtle of conservation concern native to the southeastern United States: (1) naive testosterone levels, (2) testosterone levels following a follicle stimulating hormone (FSH) challenge, (3) linear morphological measurements, and (4) geometric morphometrics. Unlike some other turtle species, male and female neonatal gopher tortoises have overlapping naive testosterone concentration distributions, justifying more complicated methods. We found that sex of neonates (<7 days old) is best predicted by a "random forest" machine learning model with naive testosterone levels and morphological measurements (8% out-of-bag error). Sex of hatchlings (4-8 months old) was predicted with 11% error using a simple threshold on naive testosterone levels, or with 4% error using a simple threshold on post-FSH testosterone levels. Sex of juveniles (approximately 3.5 years old) was perfectly predicted using a simple threshold on naive testosterone levels. Sexing hatchlings at >4 months of age is the easiest and most reliable non-surgical method for sex identification. Given access to a rearing facility and equipment to perform hormone assays, these methods have the potential to supplant laparoscopic surgery as the method of choice for sexing young gopher tortoises.

First natural breeding of the endangered dusky gopher frog (Lithobates sevosus) in captivity.

To date, all captive breeding of the dusky gopher frog, Lithobates sevosus, a federally listed endangered species, has been accomplished using in vitro fertilization (IVF). Here, we describe multievent and highly fecund captive reproduction of dusky gopher frogs driven solely by natural environmental factors. Six pairs of L. sevosus were kept in a 3.7 × 4.4 m2 outdoor enclosure designed to resemble their natural breeding habitat, which included a pool and three artificial burrows. Modifications to the enclosure that simulated temperatures and conditions within their natural range during winter were added in October and removed in late February. Following a warm, rainy period, five egg masses were laid between March 5 and 11, 2020. The number of oocytes per egg mass was 2300 ± 409 (range = 1341-3565), with the total across all five egg masses being 11,501. Of these oocytes, the hatching rate was 68.58 ± 10.05% (range = 37.53%-95.59%), with a total of 7887 successful hatchlings overall. Clutch sizes were similar to those in the wild and greater than those typically produced using IVF; thus, natural breeding can substantially increase the number of frogs available for reintroduction programs. Although assisted reproductive technologies such as IVF will continue to be useful for ensuring the success of strategic genetic pairings of captive L. sevosus, the new tool of nonassisted reproduction in specifically designed outdoor enclosures is an important advancement for the conservation and recovery of this endangered species.

Pocket gopher disturbance slows soil carbon accumulation in abandoned agricultural lands.

Soil carbon (C) sequestration rates vary widely in abandoned agricultural lands, and factors determining this variation, beyond climate, soil type, and productivity, are poorly understood. One such factor is soil disturbance by burrowing mammals. Despite being ubiquitous in all grasslands, the impact of burrowing mammals on soil C dynamics is not well understood. We quantified the major ecosystem processes that are influenced by one such burrowing mammal, plains pocket gophers (Geomys bursarius), in old field ecosystems located in east-central Minnesota, USA. We found that pocket gopher abundance varied among old fields and that newly formed gopher mounds covered up to 6% of the soil surface annually. We first measured short-term C pool and flux changes induced by gopher activities. Soil N mineralization did not differ between the soil in gopher mounds and undisturbed soil. However, for the soil under gopher mounds, N mineralization was 30% lower compared with the undisturbed soil. We developed a process model to simulate the long-term gopher disturbance impact on old field soil C accumulation. This simulation showed that pocket gophers reduced both the rate of soil C accumulation and the total C pool. This reduction is primarily driven by reduced plant C input due to the time it requires for the vegetation to recolonize gopher mounds. Soil organic matter (SOM) decomposition changes had only a minor impact. The process model showed that the depth from which burrowing mammals redistribute soil to the surface is a key factor in determining the overall impact on SOM. In total, our study indicated that soil disturbance by burrowing animals could significantly reduce C storage in old field ecosystems when the mammals are mostly active at the surface soil and can be a significant factor in decreasing overall C sequestration after land abandonment. However, at our study site, gopher abundance decreased with abandonment age, which was likely to have been cause by successional vegetation changes, therefore the gopher disturbance-induced reduction in soil C is transient and decreases with abandonment age.

COMPARISON OF SUBCARAPACIAL SINUS AND BRACHIAL VEIN PHLEBOTOMY SITES FOR BLOOD COLLECTION IN FREE-RANGING GOPHER TORTOISES (GOPHERUS POLYPHEMUS).

Paired blood samples were collected from the brachial vein and subcarapacial sinus of 42 wild gopher tortoises (Gopherus polyphemus) for comparison of hematological and plasma biochemical, vitamin, mineral, and protein electrophoresis parameters with general linear models with repeated measures designs. Comparisons revealed higher brachial vein mean values for 38 of 42 parameters with significance (P ≤ 0.05) for 21 parameters. Significantly lower brachial vein means were noted for two parameters. Coefficients of variation for brachial vein samples were lower for 30 out of 42 parameters with significantly lower values for 11 parameters. Of the 12 parameters with lower coefficients of variation for subcarapacial sinus samples, significant differences were noted for four parameters. Both the lower coefficient of variation and the higher mean values for most parameters from brachial vein samples are attributed to greater hemodilution of subcarpacial samples with lymph compared to the paired brachial vein samples. To address the clinical relevance and reliability of the parameter ranges obtained from both paired phlebotomy sites, we compared these values to those obtained from other selected investigations of gopher tortoise and desert tortoise (Gopherus agassizii) clinicopathology. Although statistically significant differences were detected, available data demonstrated that most mean ± standard deviation values and/or ranges for both phlebotomy sites of our study are similar to those reported for the selected studies. Based on these results, utilization of either set of our study values in the assessment of a gopher tortoise population or individual gopher tortoises would be acceptable for clinical or management decisions. It is also advisable that investigators develop institutional blood parameter ranges for healthy individuals by phlebotomy site when possible in addition to maintaining standardized sample collection and handling protocols.

Mitochondrial genome of Geomydoecus aurei, a pocket-gopher louse.

Parasitic lice demonstrate an unusual array of mitochondrial genome architectures and gene arrangements. We characterized the mitochondrial genome of Geomydoecus aurei, a chewing louse (Phthiraptera: Trichodectidae) found on pocket gophers (Rodentia: Geomyidae) using reads from both Illumina and Oxford Nanopore sequencing coupled with PCR, cloning, and Sanger sequencing to verify structure and arrangement for each chromosome. The genome consisted of 12 circular mitochondrial chromosomes ranging in size from 1,318 to 2,088 nucleotides (nt). Total genome size was 19,015 nt. All 37 genes typical of metazoans (2 rRNA genes, 22 tRNA genes, and 13 protein-coding genes) were present. An average of 26% of each chromosome was composed of non-gene sequences. Within the non-gene region of each chromosome, there was a 79-nt nucleotide sequence that was identical among chromosomes and a conserved sequence with secondary structure that was always followed by a poly-T region. We hypothesize that these regions may be important in the initiation of transcription and DNA replication, respectively. The G. aurei genome shares 8 derived gene clusters with other chewing lice of mammals, but in G. aurei, genes on several chromosomes are not contiguous.

Behavioural discrimination of male mental gland secretions of the gopher tortoise (Gopherus polyphemus) by both sexes.

Chemical communication is important for mate choice, especially at long distances in fragmented populations. The gopher tortoise is a social species that is threatened in the southeast U.S. due to habitat fragmentation and decline. One consequence of habitat loss is reduced mating opportunities, yet chemical signalling in gopher tortoises is relatively under-studied. Here, we investigated chemoreception of tortoise discrimination of chin secretions, or mental gland (MG) secretions. To assess conspecific recognition of male MG secretions, we conducted two paired-choice experiments: one with a neutral odorant control (NC; distilled water) and one with a pungent odorant control (PC; acetone) vs. male MG secretions. Behaviours were defined a priori, and their durations were quantified relative to treatments. Each sex spent significantly more time with MG secretions vs. acetone control during the PC study (p= 0.001). Each sex also sniffed MG swabs more frequently in both studies (PC study: p=0.0003; NC study: p=0.001). A principal components analysis of behavioural durations from the PC study identified one component with a significant treatment effect performed to MG secretions (p=0.0003), including the behaviours sniffing, head bobbing, biting, and eating near a swab. Our study provides the first chemical-behavioural bioassay of MG secretions from male gopher tortoises, suggesting MG secretions may be a source of pheromones.

The evolutionary diversity of locomotor innovation in rodents is not linked to proximal limb morphology.

Rodents are the most species-rich order within Mammalia and have evolved disparate morphologies to accommodate numerous locomotor niches, providing an excellent opportunity to understand how locomotor innovation can drive speciation. To evaluate the connection between the evolutionary success of rodents and the diversity of rodent locomotor ecologies, we used a large dataset of proximal limb CT scans from across Myomorpha and Geomyoidea to examine internal and external limb shape. Only fossorial rodents displayed a major reworking of their proximal limbs in either internal or external morphology, with other locomotor modes plotting within a generalist morphospace. Fossorial rodents were also the only locomotor mode to consistently show increased rates of humerus/femur morphological evolution. We propose that these rodent clades were successful at spreading into ecological niches due to high behavioral plasticity and small body sizes, allowing them to modify their locomotor mode without requiring major changes to their proximal limb morphology.

Amino acid and acetylcholine chemistry in mountain beaver cochlear nucleus and comparisons to pocket gopher, other rodents, and cat.

The mountain beaver and pocket gopher are two rodents that live mostly underground in tunnel systems. Previous studies have suggested that their cochlear nucleus structure, particularly that of the dorsal cochlear nucleus (DCN), differs significantly from that of other mammals, that the hearing ability of the pocket gopher is deficient compared to that of other rodents, and that the DCN of the mountain beaver is more responsive to slow oscillations of air pressure than to sounds. We conducted some electrophysiological recordings from mountain beaver DCN and then used microchemical methods to map in mountain beaver cochlear nuclei the distributions of amino acids, including the major neurotransmitters of the brain, and enzyme activities related to the metabolism of the neurotransmitter acetylcholine, which functions in centrifugal pathways to the cochlear nucleus. Similar measurements were made for a pocket gopher cochlear nucleus. Responses to tonal stimuli were found in mountain beaver DCN. Distributions and magnitudes of neurotransmitter and related amino acids within mountain beaver and pocket gopher cochlear nuclei were not very different from those of other rodents and cat. However, the enzyme of synthesis for acetylcholine, choline acetyltransferase, had only low activities in the DCN of both mountain beaver and pocket gopher. The chemical distributions in the mountain beaver DCN support a conclusion that it corresponds to just the superficial DCN portion of other mammals. High correlations between the concentrations of γ-aminobutyrate (GABA) and glycine were found for both mountain beaver and pocket gopher cochlear nuclei, suggesting that their co-localization in cochlear nucleus synapses may be especially prominent in these animals. Previous evidence suggests convergence of somatosensory and auditory information in the DCN, and this may be especially true in animals spending most of their time underground. Our results suggest that the enlarged DCN of the mountain beaver and that of the pocket gopher are not very different from those of other rodents with respect to involvement of amino acid neurotransmitters, but they appear to have reduced cholinergic innervation.

Tunnel-tube and Fourier methods for measuring three-dimensional medium reaction force in burrowing animals.

Subterranean digging behaviors provide opportunities for protection, access to prey, and predator avoidance for a diverse array of vertebrates, yet studies of the biomechanics of burrowing have been limited by the technical challenges of measuring kinetics and kinematics of animals moving within a medium. We describe a new system for measuring 3D reaction forces during burrowing, called a 'tunnel-tube', which is composed of two, separately instrumented plastic tubes: an 'entry tube' with no medium, in series with a 'digging tube' filled with medium. Mean reaction forces are measured for a digging bout and Fourier analysis is used to quantify the amplitude of oscillatory digging force as a function of frequency. In sample data from pocket gophers digging in artificial and natural media, the mean ground reaction force is constant, whereas Fourier analysis resolves a reduced amplitude of oscillatory force in the artificial medium with lower compaction strength.

Locomotory adaptations in entoptychine gophers (Rodentia: Geomyidae) and the mosaic evolution of fossoriality.

Pocket gophers (family Geomyidae) are the dominant burrowing rodents in North America today. Their fossil record is also incredibly rich; in particular, entoptychine gophers, a diverse extinct subfamily of the Geomyidae, are known from countless teeth and jaws from Oligocene and Miocene-aged deposits of the western United States and Mexico. Their postcranial remains, however, are much rarer and little studied. Yet, they offer the opportunity to investigate the locomotion of fossil gophers, shed light on the evolution of fossoriality, and enable ecomorphological comparisons with contemporaneous rodents. We present herein a quantitative study of the cranial and postcranial remains of eight different species of entoptychine gophers as well as many contemporary rodent species. We find a range of burrowing capabilities within Entoptychinae, including semifossorial scratch-digging animals and fossorial taxa with cranial adaptations to burrowing. Our results suggest the repeated evolution of chisel-tooth digging across genera. Comparisons between entoptychine gophers and contemporaneous rodent taxa show little ecomorphological overlap and suggest that the succession of burrowing rodent taxa on the landscape may have had more to do with habitat partitioning than competition.

Bioturbation by mammals and fire interact to alter ecosystem-level nutrient dynamics in longleaf pine forests.

Activities of ecosystem engineers can interact with other disturbances to modulate rates of key processes such as productivity and nutrient cycling. Bioturbation, movement of soil by organisms, is a widespread form of ecosystem engineering in terrestrial ecosystems. We propose that bioturbation by southeastern pocket gophers (Geomys pinetis), an abundant but declining ecosystem engineer in longleaf pine (Pinus palustris Mill.) forests, accelerates nutrient dynamics of the forest floor by burying litter and then reduces litter consumption and nitrogen (N) volatilization losses in the presence of fire. We evaluated our hypothesis by measuring how litter burial alters decomposition and N and phosphorus (P) turnover of longleaf pine and turkey oak (Quercus laevis Walt.) litter over four years, and then simulated interactive ecosystem-level effects of litter burial and low-intensity fires on N and P dynamics of the litter layer. In the field, mass loss was over two times greater and N and P were released much more rapidly from litter buried beneath mounds than on the surface of the forest floor. At a measured rate of mound formation covering 2.3 ± 0.6% of the forest floor per year, litter mass and N and P content of the forest floor simulated over an eight-year period were approximately 11% less than amounts in areas without pocket gopher mounds. In contrast to unburied litter, litter beneath mounds is protected from consumption during fires, and as fire interval increased, consumption rates decreased because mounds cover more years of accumulated litter. Our research indicates that bioturbation and burial of litter by pocket gophers accelerates turnover of N and P on the forest floor, and in the presence of fire, conserves N in this ecosystem where productivity is known to be nutrient limited.

Development and Characterization of 12 Novel Polymorphic Microsatellite Loci for the Mammal Chewing Louse Geomydoecus aurei (Insecta: Phthiraptera) and a Comparison of Next-Generation Sequencing Approaches for Use in Parasitology.

Next-generation sequencing methodologies open the door for evolutionary studies of wildlife parasites. We used 2 next-generation sequencing approaches to discover microsatellite loci in the pocket gopher chewing louse Geomydoecus aurei for use in population genetic studies. In one approach, we sequenced a library enriched for microsatellite loci; in the other approach, we mined microsatellites from genomic sequences. Following microsatellite discovery, promising loci were tested for amplification and polymorphism in 390 louse individuals from 13 pocket gopher hosts. In total, 12 loci were selected for analysis (6 from each methodology), none of which exhibited evidence of null alleles or heterozygote deficiencies. These 12 loci showed adequate genetic diversity for population-level analyses, with 3-9 alleles per locus with an average HE per locus ranging from 0.32 to 0.70. Analysis of Molecular Variance (AMOVA) indicated that genetic variation among infrapopulations accounts for a low, but significant, percentage of the overall genetic variation, and individual louse infrapopulations showed FST values that were significantly different from zero in the majority of pairwise infrapopulation comparisons, despite all 13 infrapopulations being taken from the same locality. Therefore, these 12 polymorphic markers will be useful at the infrapopulation and population levels for future studies involving G. aurei. This study shows that next-generation sequencing methodologies can successfully be used to efficiently obtain data for a variety of evolutionary questions.

Novel and current rodenticides for pocket gopher Thomomys spp. management in vineyards: what works?

BACKGROUND: Rodenticides are often included as part of an integrated pest management approach for managing pocket gophers (Thomomys spp.) given that they are relatively quick and inexpensive to apply. Strychnine has historically been the most effective toxicant for pocket gophers, but its use is currently limited in the United States; alternative registered toxicants have not proven effective. Recent research with baits containing cholecalciferol plus anticoagulant toxicants proved effective against pocket gophers in a lab setting. Therefore, we established a field study to compare cholecalciferol plus anticoagulant combinations [0.03% cholecalciferol plus 0.005% diphacinone (C + D), 0.015% cholecalciferol plus 0.0025% brodifacoum (C + B1), 0.03% cholecalciferol plus 0.0025% brodifacoum (C + B2)] with strychnine (0.5%) for pocket gopher management. RESULTS: Strychnine treatments resulted in 100% efficacy after two treatment periods. Both C + D and C + B2 resulted in efficacy significantly greater than 70% after two treatment periods (83 and 75% respectively). Efficacy from C + B1 (85%) was not significantly greater than 70%, but did yield high overall efficacy as well. CONCLUSION: Although strychnine remains the most effective rodenticide for pocket gopher control, the cholecalciferol plus anticoagulant baits tested would be a good alternative when strychnine is unavailable. C + D may be the best option given that it uses a first-generation anticoagulant as the synergist. © 2016 Society of Chemical Industry.