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opencc-zeroDec 2014View details →

Data from: Revision of the first therocephalian, Theriognathus Owen (Therapsida: Whaitsiidae), and implications for cranial ontogeny and allometry in nonmammaliaform eutheriodonts

Historically, the whaitsiid therocephalian Theriognathus Owen was one of the earliest described nonmammalian therapsids, its morphology helping to link phylogenetically the Paleozoic synapsids of North America and southern Africa to their mammalian successors. However, decades of taxonomic over-splitting and superficial descriptions obscured the morphologic diversity of the genus, hindering its utility as a study system for the evolution of synapsid cranial function as well as its biostratigraphic significance in the Late Permian of southern Africa. Here, we revise the status and provenance of all the known specimens of Theriognathus from South Africa, Tanzania, and Zambia. We present both qualitative and quantitative support for the presence of a single morphospecies as proposed by some authors. Proportional differences in skulls that were previously ascribed to different morphotypes ('Aneugomphius,' 'Notosollasia,' 'Moschorhynchus,' and 'Whaitsia') are largely size-related and allometric trends are considered here in the context of jaw function and prey prehension. Our results suggest that the single species, Theriognathus microps, represented one of the most abundant Late Permian therocephalians in southern Africa and is consequently a potentially useful biostratigraphic marker for the upper Cistecephalus-lower Dicynodon Assemblage Zone transition (i.e., late Wuchiapingian). The wide range of preserved sizes in conjunction with recent paleohistological evidence supports that individuals spent much of their lives in an actively-growing, subadult phase. Later Dicynodon Assemblage Zone records (e.g., upper Balfour Formation) are unconfirmed as the genus was likely replaced by other theriodont predators (e.g., Moschorhinus) leading up to the Permo-Triassic boundary in the Karoo Basin of South Africa.

opencc-zeroDec 2016View details →

Data from: Horizontal and vertical movements of Caribbean reef sharks (Carcharhinus perezi): conservation implications of limited migration in a marine sanctuary

Despite the ecological and economic importance of the Caribbean reef shark (Carcharhinus perezi), little data exist regarding the movements and habitat use of this predator across its range. We deployed 11 pop-up satellite archival tags on Caribbean reef sharks captured in the northeast Exuma Sound, The Bahamas, to assess their horizontal and vertical movements throughout the water column. Sharks showed high site fidelity to The Bahamas suggesting Bahamian subpopulations remain protected within the Bahamian Shark Sanctuary. Depth data indicate that Caribbean reef sharks spent a significant proportion (72–91%) of their time above 50 m in narrow vertical depth bands, which varied considerably on an individual basis. This may be indicative of high site fidelity to specific bathymetric features. Animals exhibited three broadly categorized sporadic off-bank excursions (more than 50 m excursions) down to a depth of 436.1 m, which were more frequent during the night. These deeper excursions during night may be indicative of foraging in relation to prey on mesophotic reefs, as well as diel-vertically migrating prey from the deeper meso- and bathypelagic zones. These vertical movements suggest that Caribbean reef sharks can be significant vectors of ecosystem connectivity further warranting holistic multi-system management and conservation approaches.

opencc-zeroDec 2017View details →

Data from: Implications of survey effort on estimating demographic parameters of a long-lived marine top predator

Effective management of wildlife populations rely on knowledge of their abundance, survival and reproductive rates. Maintaining long-term studies capable of estimating demographic parameters for long-lived, slow reproducing species is challenging. Insights into effects of research intensity on the statistical power to estimate demographic parameters is limited. Here, we investigate implications of survey effort on estimating abundance, home range sizes and reproductive output of Indo-Pacific bottlenose dolphins (Tursiops aduncus), using a three-year sub-sample of a long-term, capture-recapture study off Bunbury, Western Australia. Photo-identification on individual dolphins were collected following Pollock's Robust Design, where seasons were defined as 'primary periods', each consisting of multiple 'secondary periods'. The full dataset consisted of 12 primary periods and 72 secondary periods, resulting in the study area being surveyed 24 times/year. We simulated reduced survey effort by randomly removing one, two or three secondary periods per primary period. Capture-recapture models were used to assess the effect of survey intensity on the power to detect trends in population abundance, while individual dolphin sighting histories were used to assess the ability to conduct home range analyses. We used sighting records of adult females and their calving histories to assess survey effort on quantifying reproductive output. A 50% reduction in survey effort resulted in: i) up to a 36% decline in population abundance at the time of detection; ii) a reduced ability to estimate home range sizes, by increasing the time for individuals to be sighted on >30 occasions (an often-used metric for home range analyses) from 7.74 to 15.46 years; and iii) 33%, 24% and 33% of annual calving events going undocumented in their year of birth. Results clearly illustrate the importance of survey effort on the ability to assess demographic parameters with clear implications for population viability analyses, population forecasting and conservation efforts to manage human-wildlife interactions.

opencc-zeroDec 2017View details →

Data from: Near absence of differential gene expression in the retina of rainbow trout after exposure to a magnetic pulse: implications for magnetoreception

The ability to perceive Earth's magnetic field, or magnetoreception, exists in numerous animals. Although the mechanism underlying magnetoreception has not been clearly established in any species, in salmonid fish it is hypothesized to occur by means of crystals of magnetite associated with nervous tissue such as the brain, olfactory organ, or retina. In this study, rainbow trout (Oncorhynchus mykiss) were exposed to a brief magnetic pulse known to disrupt magnetic orientation behavior in several animals. Changes in gene expression induced by the pulse were then examined in the retina. Analyses indicated that the pulse elicited differential expression of only a single gene, gamma-crystallin M3-like (crygm3). The near-absence of an effect of the magnetic pulse on gene expression in the retina stands in sharp contrast to a recent study in which 181 genes were differentially expressed in brain tissue of O. mykiss after exposure to the same pulse. Overall, our results suggest either that magnetite-based magnetoreceptors in trout are not located in the retina, or else that they are unaffected by magnetic pulses that can disrupt magnetic orientation behavior in animals.

opencc-zeroDec 2015View details →

Data from: Unlinked Mendelian inheritance of red and black pigmentation in snakes: implications for Batesian mimicry

Identifying the genetic basis of mimetic signals is critical to understanding both the origin and dynamics of mimicry over time. For species not amenable to large laboratory breeding studies, widespread color polymorphism across natural populations offers a powerful way to assess the relative likelihood of different genetic systems given observed phenotypic frequencies. We classified color phenotype for 2,175 ground snakes (Sonora semiannulata) across the continental United States to analyze morph ratios and test among competing hypotheses about the genetic architecture underlying red and black coloration in coral snake mimics. We found strong support for a two-locus model under simple Mendelian inheritance, with red and black pigmentation being controlled by separate loci. We found no evidence of either linkage disequilibrium between loci or sex linkage. In contrast to Batesian mimicry systems like butterflies in which all color signal components are linked into a single "supergene," our results suggest that the mimetic signal in colubrid snakes can be disrupted through simple recombination and that color evolution is likely to involve discrete gains and losses of each signal component. Both outcomes are likely to contribute to the exponential increase in rates of color evolution seen in snake mimicry systems over insect systems.

opencc-zeroDec 2014View details →

Data from: Algal toxin impairs sea lion memory and hippocampal connectivity, with implications for strandings

Domoic acid (DA) is a naturally occurring neurotoxin known to harm marine animals. DA-producing algal blooms are increasing in size and frequency. Although chronic exposure is known to produce brain lesions, the influence of DA toxicosis on behavior in wild animals is unknown. We showed, in a large sample of wild sea lions, that spatial memory deficits are predicted by the extent of right dorsal hippocampal lesions related to natural exposure to DA and that exposure also disrupts hippocampal-thalamic brain networks. Because sea lions are dynamic foragers that rely on flexible navigation, impaired spatial memory may affect survival in the wild.

opencc-zeroDec 2017View details →

Data from: Effects of 4-Hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107) on liver transcriptome in rats: implication in the disruption of circadian rhythm and fatty acid metabolism

Polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) have been detected in tissues of both wild animals and humans. Several previous studies have suggested adverse effects of OH-PCBs on the endocrine and nervous systems in mammals. However, there have been no studies on transcriptome analysis of the effects of OH-PCBs, and thus, the whole picture and mechanisms underlying the adverse effects induced by OH-PCBs are still poorly understood. We therefore investigated the mRNA expression profile in the liver of adult male Wistar rats treated with 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107) to explore the genes responsive to OH-PCBs and to understand the potential effects of the chemical. Next-generation RNA sequencing analysis revealed changes in the expression of genes involved in the circadian rhythm and fatty acid metabolism, such as nuclear receptor subfamily 1, group D, member 1 (Nr1d1), aryl hydrocarbon receptor nuclear translocator-like protein 1 (Arntl), cryptochrome circadian clock 1 (Cry1), and enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase (Ehhadh), in 4-OH-CB107-treated rats. In addition, biochemical analysis of the plasma revealed a dose-dependent increase in the leucine aminopeptidase (LAP), indicating the onset of liver damage. These results suggest that OH-PCB exposure may induce liver injury as well as disrupt the circadian rhythm and peroxisome proliferator-activated receptor (PPAR)-related fatty acid metabolism.

opencc-zeroOct 2019View details →

Is there an oxidative cost of acute stress? Characterization, implication of glucocorticoids, and modulation by prior stress experience

Acute rises in glucocorticoid hormones allow individuals to adaptively respond to environmental challenges but may also have negative consequences, including oxidative stress. While the effects of chronic glucocorticoid exposure on oxidative stress have been well characterized, those of acute stress or glucocorticoid exposure have mostly been overlooked. We examined the relationship between acute stress exposure, glucocorticoids, and oxidative stress in Japanese quail (Coturnix japonica). We (i) characterized the pattern of oxidative stress during an acute stressor in two phenotypically distinct breeds, (ii) determined whether corticosterone ingestion, in the absence of acute stress, increased oxidative stress, which we call Glucocorticoid-induced Oxidative Stress (GiOS), and (iii) explored how prior experience to stressful events affected GiOS. Both breeds exhibited an increase in oxidative stress in response to an acute stressor. Importantly, in the absence of acute stress, ingesting corticosterone caused an acute rise in plasma corticosterone and oxidative stress. Lastly, birds exposed to no previous acute stress or numerous stressful events had high levels of GiOS in response to acute stress, while birds with moderate prior exposure did not. Together, these findings suggest that an acute stress response results in GiOS, but prior experience to stressors may modulate that oxidative cost.

opencc-zeroDec 2016View details →

Data from: Elevated salinity blocks pathogen transmission and improves host survival for a globally pandemic disease: implications for amphibian translocations

1. Emerging infectious diseases are one of the greatest threats to global biodiversity. Chytridiomycosis in amphibians is perhaps the most extreme example of this phenomenon known to science. Translocations are increasingly used to fight disease-induced extinctions. However, many programs fail because disease is still present or subsequently establishes in the translocation environment. There is a need for studies in real-world scenarios to test whether environmental manipulation could improve survival in populations by generating unfavourable environmental conditions for pathogens. Reintroductions of amphibians impacted by chytridiomycosis into environments where the disease persists provide a scenario where this paradigm can be tested. 2. We tested the hypothesis that manipulating environmental salinity in outdoor mesocosms under near identical environmental conditions applying in a nearby translocation program for an endangered amphibian, would improve survival and determine the mechanisms involved. 160 infected and 288 uninfected, captive-bred, juvenile frogs were released into 16 outdoor mesocosms in which salinity was controlled (high or low salinity treatment). The experiment was run for 25 weeks from the mid-austral winter to the mid-austral summer of 2013 in a temperate coastal environment, Australia. 3. Increasing salinity from ca. 0.5 ppt to 3.5 - 4.5 ppt reduced pathogen transmission between infected and uninfected animals, resulting in significantly reduced mortality in elevated salt mesocosms (0.13, high salt versus 0.23, low salt survival at 23 weeks). Increasing water temperature associated with season (from mean 13oC to 25oC) eventually cleared all surviving animals of the pathogen. 4. Synthesis and applications. We identified a mechanism by which environmental salinity can protect amphibian hosts from chytridomycosis by reducing disease transmission rates and conclude that manipulating environmental salinity in landscapes where chytrid-affected amphibians are currently translocated could improve the probability of population persistence for hundreds of species. More broadly, we provide support for the paradigm that environmental manipulation can be used to mitigate the impact of emerging infectious diseases.18-Sep-2017

opencc-zeroDec 2014View details →

Data from: Aggregation of infective stages of parasites as an adaptation and its implications for the study of parasite-host interactions

The causes and consequences of aggregation among conspecifics have received much attention. For infecting macroparasites, causes include variation among hosts in susceptibility, and/or whether infective stages are aggregated in the environment. Here, we link these two phenomena and explore whether aggregation of infective stages in the environment is adaptive to parasites encountering host condition-linked defenses, and what effect such aggregations have for parasite-host interactions. Using simulation models, we show that parasite fitness is increased by aggregates attacking a host, particularly when investment into defenses is high. The fitness benefit of aggregation remains despite inclusion of factors that should curb the benefits of aggregation: namely, mortality of low condition hosts (those hosts expected to be most susceptible to parasitism) and costs of high coinfection. Using sample sizes common in studies, aggregation of infective stages reduces the likelihood of detecting host condition-parasitism relations, even when host condition is the only other factor in models affecting parasitism. Thus, it is not surprising that the expected inverse relations between host condition and parasitism, commonly a premise in studies of parasite-host interactions, are inconsistently found. An understanding of how parasites encounter hosts is thus needed for developing theory for parasite-host ecological and evolutionary interactions.

opencc-zeroJun 2021View details →

Gradients of genetic diversity and differentiation across the distribution range of a Mediterranean coral: patterns, processes and conservation implications.

The aim of this study was to determine how historical and contemporary eco-evolutionary processes shape the patterns of genetic diversity and differentiation across species' distribution range remains an open question with strong conservation implications. Focusing on the orange stony coral, Astroides calycularis, we i) characterized the pattern of neutral genetic diversity across the distribution range; ii) gave insights into the underlying processes; and iii) discussed conservation implications with emphasis on a national park located on a hotspot of genetic diversity. Location: South Mediterranean Sea and Zembra National Park. We combined new data from 12 microsatellites in 13 populations located in the Centre and in the Western Periphery of the distribution range with a published dataset including 16 populations from the Western and Eastern Peripheries. We analysed the relationship among parameters of genetic diversity (He, Ar(g)) and structure (population-specific FST) and two measures of geographic peripherality. We compared two estimators of pairwise genetic structure (GST, DEST) across the distribution range. The evolutionary and demographic history of the populations following the Last Glacial Maximum was reconstructed using approximate Bayesian computations and Maximum Likelihood analyses. We inferred the contemporary connectivity among populations from Zembra National Park and with the neighbouring area of Cap Bon. We demonstrate a decrease of genetic diversity and an increase of genetic differentiation from the Centre to the Eastern and Western Peripheries of the distribution range. Populations from Zembra show the highest genetic diversity reported in the species. We identified a spillover effect towards Cap Bon. The patterns of genetic diversity and differentiation are most likely explained by "the postglacial range expansion hypothesis" rather than the "central-peripheral hypothesis". Enforcement of conservation measures should be considered to protect this genetic diversity pattern, in particular when considering the low effective population size inferred at many sites.

opencc-by-4.0May 2003View details →

Figs. 7–9. Parabuthus muelleri Prendini, 2000 in Discovery of the Male of Parabuthus muelleri, and Implications for the Phylogeny of Parabuthus (Scorpiones: Buthidae)

Figs. 7–9. Parabuthus muelleri Prendini, 2000, male (AMNH [AH 3991]), distribution of trichobothria and macrosetae on the dextral pedipalpal chela. 7. Dorsal aspect. 8. Ventral aspect. 9. Internal aspect. Scale bar = 1 mm.

FIGURES 7 in Molecular relationships of the Australian Ennominae (Lepidoptera: Geometridae) and implications for the phylogeny of the Geometridae from molecular and morphological data

FIGURES 7. Two dimensional structure of a 28S D2 gene fragment for Monoctenia falernaria.

FIGURES 8 in Molecular relationships of the Australian Ennominae (Lepidoptera: Geometridae) and implications for the phylogeny of the Geometridae from molecular and morphological data

FIGURES 8. Two dimensional structure of a 28S D2 gene fragment for Palleopa innotata.

FIGURES 6 in Molecular relationships of the Australian Ennominae (Lepidoptera: Geometridae) and implications for the phylogeny of the Geometridae from molecular and morphological data

FIGURES 6. Two dimensional structure of a 28S D2 gene fragment for Archiearis parthenias.

FIGURES 5 in Molecular relationships of the Australian Ennominae (Lepidoptera: Geometridae) and implications for the phylogeny of the Geometridae from molecular and morphological data

FIGURES 5. Two dimensional structure of a 28S D2 gene fragment for Alsophila aescularia.

opennotspecifiedSep 2007View details →

FIGURE 1 in Conservation implications of a morphometric comparison between the Illinois Chorus Frog (Pseudacris streckeri illinoensis) and Strecker's Chorus Frog (P. s. streckeri) (Anura: Hylidae) from Arkansas, Illinois, Missouri, Oklahoma, and Texas

FIGURE 1. Counties with documented populations of ICFs and SCFs.

opennotspecifiedSep 2007View details →

FIGURE 2 in Discovery of the genus Plethodontohyla (Anura: Microhylidae) in dry western Madagascar: description of a new species and biogeographic implications

FIGURE 2. Plethodontohyla fonetana, holotype (ZSM 123/2006) in ventral view, photographed in life.

opennotspecifiedOct 2014View details →

FIGURE 4 in Aetokthonos hydrillicola gen. et sp. nov.: Epiphytic cyanobacteria on invasive aquatic plants implicated in Avian Vacuolar Myelinopathy

FIGURE 4. Line drawing showing branching pattern (artist: Bradley Bartelme). Scale = 10 μm.