PubMed | Greer Laboratory, Catalina Island Conservancy, University of California at Davis and Institute for Wildlife Studies
Type: Journal Article | Journal: PloS one | Year: 2015
Ear mites (Otodectes cynotis) and ear canal tumors are highly prevalent among federally endangered Island foxes (Urocyon littoralis catalinae) living on Santa Catalina Island off the coast of Southern California. Since studies began in the 1990s, nearly all foxes examined were found to be infected with ear mites, and ceruminous gland tumors (carcinomas and adenomas) were detected in approximately half of all foxes 4 years of age. We hypothesized that reduction of ear mite infection would reduce otitis externa and ceruminous gland hyperplasia, a risk factor for tumor development. In this study, we conducted a randomized field trial to assess the impact of acaricide treatment on ear mite prevalence and intensity of infection, otitis externa, ceruminous gland hyperplasia, and mite-specific IgG and IgE antibody levels. Treatment was highly effective at eliminating mites and reducing otitis externa and ceruminous gland hyperplasia, and mite-specific IgG antibody levels were significantly lower among uninfected foxes. Ceruminous gland hyperplasia increased in the chronically infected, untreated foxes during the six month study. Our results provide compelling evidence that acaricide treatment is an effective means of reducing ear mites, and that mite removal in turn reduces ear lesions and mite-specific IgG antibody levels in Santa Catalina Island foxes. This study has advanced our understanding of the underlying pathogenesis which results in ceruminous gland tumors, and has helped inform management decisions that impact species conservation.
PubMed | Catalina Island Conservancy, University of California at Davis and Institute for Wildlife Studies
Type: Journal Article | Journal: PloS one | Year: 2015
In this study, we examined the prevalence, pathology, and epidemiology of tumors in free-ranging island foxes occurring on three islands in the California Channel Islands, USA. We found a remarkably high prevalence of ceruminous gland tumors in endangered foxes (Urocyon littoralis catalinae) occurring on Santa Catalina Island (SCA)--48.9% of the dead foxes examined from 2001-2008 had tumors in their ears, and tumors were found in 52.2% of randomly-selected mature ( 4 years) foxes captured in 2007-2008, representing one of the highest prevalences of tumors ever documented in a wildlife population. In contrast, no tumors were detected in foxes from San Nicolas Island or San Clemente Island, although ear mites (Otodectes cynotis), a predisposing factor for ceruminous gland tumors in dogs and cats, were highly prevalent on all three islands. On SCA, otitis externa secondary to ear mite infection was highly correlated with ceruminous gland hyperplasia (CGH), and tumors were significantly associated with the severity of CGH, ceruminous gland dysplasia, and age group (older foxes). We propose a conceptual model for the formation of ceruminous gland tumors in foxes on SCA that is based on persistent, ubiquitous infection with ear mites, and an innate, over exuberant inflammatory and hyperplastic response of SCA foxes to these mites. Foxes on SCA are now opportunistically treated with acaricides in an attempt to reduce mite infections and the morbidity and mortality associated with this highly prevalent tumor.
Duncan C.L.,Catalina Island Conservancy |
Duncan C.L.,California State University, Fullerton |
King J.L.,Catalina Island Conservancy |
Kirkpatrick J.F.,Science and Conservation Center
Journal of Zoo and Wildlife Medicine | Year: 2013
Prior to 2010, the introduced population of American bison (Bison bison) on Santa Catalina Island, California, was managed through the shipment of surplus bison to private ranches, Native American reservations, and livestock auctions on the mainland. In response to escalating costs, transport-induced stress to the animals, and ecologic impacts associated with high bison numbers on-island between shipments, the use of the immunocontraceptive vaccine porcine zona pellucida (PZP) as a fertility control option for managing the population was investigated. Between 2009 and 2012, a total of 64 bison cows (≥1 yr old) received primer inoculations of 100 μg PZP emulsified with 0.5 ml Freund's modified adjuvant (FMA) delivered through a combination of intramuscular injections by hand (50 bison cows) during roundups and via field darting (14 bison cows). Pre-rut booster inoculations of 100 μg PZP emulsified with 0.5 ml Freund's incomplete adjuvant (FIA) were administered exclusively via field darting in 2010, 2011, and 2012 to 45, 48, and 61 bison cows (≥1 yr old), respectively. During the present study, 38 adult cows (marked and unmarked) received one or more PZP inoculations during their first, second, or third trimesters of pregnancy, and of these individuals, 35 successfully produced calves. Low pregnancy values detected in the remaining three cows have been attributed to residual progesterone associated with unsuccessful fertilization. The 2010 pretreatment calving rate (calves born per cow) determined via direct observation was 67.4% (29 calves from 43 cows). Through the use of PZP, the calving rate was reduced to 10.4% by 2011 and to 3.3% by 2012. Considering the annual mortality rate of 2-5% documented during this study, the results demonstrate the potential of PZP use as an effective nonlethal tool for controlling population growth in free-ranging bison. © Copyright 2013 by American Association of Zoo Veterinarians.
PubMed | Catalina Island Conservancy, The Nature Conservancy, Colorado State University, Smithsonian Institution and 4 more.
Type: Journal Article | Journal: PloS one | Year: 2015
Island endemics are typically differentiated from their mainland progenitors in behavior, morphology, and genetics, often resulting from long-term evolutionary change. To examine mechanisms for the origins of island endemism, we present a phylogeographic analysis of whole mitochondrial genomes from the endangered island fox (Urocyon littoralis), endemic to Californias Channel Islands, and mainland gray foxes (U. cinereoargenteus). Previous genetic studies suggested that foxes first appeared on the islands >16,000 years ago, before human arrival (~13,000 cal BP), while archaeological and paleontological data supported a colonization >7000 cal BP. Our results are consistent with initial fox colonization of the northern islands probably by rafting or human introduction ~9200-7100 years ago, followed quickly by human translocation of foxes from the northern to southern Channel Islands. Mitogenomes indicate that island foxes are monophyletic and most closely related to gray foxes from northern California that likely experienced a Holocene climate-induced range shift. Our data document rapid morphological evolution of island foxes (in ~2000 years or less). Despite evidence for bottlenecks, island foxes have generated and maintained multiple mitochondrial haplotypes. This study highlights the intertwined evolutionary history of island foxes and humans, and illustrates a new approach for investigating the evolutionary histories of other island endemics.
PubMed | Catalina Island Conservancy, The Nature Conservancy, University of Maryland University College, Naval Facilities Engineering Command Southwest and 9 more.
Type: Journal Article | Journal: Molecular ecology | Year: 2016
The evolutionary mechanisms generating the tremendous biodiversity of islands have long fascinated evolutionary biologists. Genetic drift and divergent selection are predicted to be strong on islands and both could drive population divergence and speciation. Alternatively, strong genetic drift may preclude adaptation. We conducted a genomic analysis to test the roles of genetic drift and divergent selection in causing genetic differentiation among populations of the island fox (Urocyon littoralis). This species consists of six subspecies, each of which occupies a different California Channel Island. Analysis of 5293 SNP loci generated using Restriction-site Associated DNA (RAD) sequencing found support for genetic drift as the dominant evolutionary mechanism driving population divergence among island fox populations. In particular, populations had exceptionally low genetic variation, small Ne (range=2.1-89.7; median=19.4), and significant genetic signatures of bottlenecks. Moreover, islands with the lowest genetic variation (and, by inference, the strongest historical genetic drift) were most genetically differentiated from mainland grey foxes, and vice versa, indicating genetic drift drives genome-wide divergence. Nonetheless, outlier tests identified 3.6-6.6% of loci as high FST outliers, suggesting that despite strong genetic drift, divergent selection contributes to population divergence. Patterns of similarity among populations based on high FST outliers mirrored patterns based on morphology, providing additional evidence that outliers reflect adaptive divergence. Extremely low genetic variation and small Ne in some island fox populations, particularly on San Nicolas Island, suggest that they may be vulnerable to fixation of deleterious alleles, decreased fitness and reduced adaptive potential.
News Article | December 7, 2015
Roughly half of adult foxes examined between 2001 and 2008 had tumors in their ears, with about two-thirds of those malignant, according to a UC Davis study published this month in the journal PLOS ONE. More than 98 percent of the foxes were also infected with ear mites. These mites appear to be a predisposing factor for ear tumors in the Santa Catalina Island fox. Luckily for the foxes, the story doesn't stop there. "We established a high prevalence of both tumors and ear mites, and hypothesized that there was something we could potentially do about it, which now appears to be significantly helping this population," said Winston Vickers, lead author of the prevalence study and an associate veterinarian with the UC Davis Wildlife Health Center at the UC Davis School of Veterinary Medicine. Working closely with researchers from the Institute for Wildlife Studies and Catalina Island Conservancy, the scientists conducted one of the few studies to estimate disease prevalence in an entire free-living wildlife population. A complementary study, also led by UC Davis and published in PLOS ONE today, found that treatments with acaracide, a chemical agent used to kill ear mites in dogs and cats, reduced the prevalence of ear mite infection dramatically, from 98 percent to 10 percent among treated foxes at the end of the six-month trial. Ear canal inflammation and other signs of developing ear tumors also dropped. "It's rare to have a success story," said the ear mite study's lead author, Megan Moriarty, a student with the UC Davis School of Veterinary Medicine when the study began and currently a staff research associate at the UC Davis Wildlife Health Center. "It was interesting to see such striking results over a relatively short time period." Santa Catalina Island foxes are intensively managed by the Catalina Island Conservancy. In 2009, when the mite treatment study began, the Conservancy added acaracide to the variety of preventative treatments they administer to the foxes each year. The Conservancy confirms that, in the years since, the overall prevalence of ear mites has dramatically declined in the areas they normally catch and treat foxes, as have the rates of tissue masses in the ear canals, suggesting reduced tumor presence. "The annual prophylactic acaracide treatment has greatly improved the overall condition of the foxes' ear canals," said Julie King, the Conservancy's director of Conservation and Wildlife Management and co-author of both studies. "Within just a few months post treatment, the presence of wax, infection, inflammation, and pigmentation virtually disappear. We have also noted an apparent reduction in the number of tumors observed, despite the fact that the absence of wax and other obstructions has made them easier to detect." Conservancy biologists have also documented a cascade effect on the foxes' offspring, since most young foxes get the ear mites from their parents. "Prior to treatment in 2009, approximately 90 percent of all pups handled had ear mites, whereas by 2015, mites were detected in only 15 percent of new pups." King said. The studies pose new questions. For instance, the mite treatment certainly reduces the prevalence and severity of mite infection, as well as risk factors for tumor development, but what effect will it have on overall tumor and cancer rates for these foxes in the long term? Also, ear mites infect other Channel Island foxes, but those foxes don't develop ear canal tumors. So why are Santa Catalina Island foxes predisposed to these tumors and not other Channel Island foxes? Vickers and colleagues are preparing to research possible genetic reasons for this. "Catalina foxes have an over-exuberant tissue reaction to the same stimuli—the mites—and that appears to lead to the tumors," Vickers said. "That's why we gravitate toward genetics in addition to other factors." The Santa Catalina Island fox is one of six subspecies native to the Channel Islands off the coast of Southern California. Its population declined dramatically in 1999 when a distemper epidemic decimated up to 90 percent of the population, prompting the federal endangered species listing for the roughly 150 foxes remaining. The population has since rebounded to an estimated 1,717 foxes. Explore further: Once nearly extinct, wild foxes on Catalina Island making a comeback More information: T. Winston Vickers et al. Pathology and Epidemiology of Ceruminous Gland Tumors among Endangered Santa Catalina Island Foxes (Urocyon littoralis catalinae) in the Channel Islands, USA, PLOS ONE (2015). DOI: 10.1371/journal.pone.0143211 Moriarty ME, Vickers TW, Clifford DL, Garcelon DK, Gaffney PM, Lee KW, et al. (2015) Ear Mite Removal in the Santa Catalina Island Fox (Urocyon littoralis catalinae): Controlling Risk Factors for Cancer Development. PLoS ONE 10(12): e0144271. DOI: 10.1371/journal.pone.0144271
Derr J.N.,Texas A&M University |
Hedrick P.W.,Arizona State University |
Halbert N.D.,Texas A&M University |
Plough L.,University of Southern California |
And 6 more authors.
Conservation Biology | Year: 2012
Hybridization between endangered species and more common species is a significant problem in conservation biology because it may result in extinction or loss of adaptation. The historical reduction in abundance and geographic distribution of the American plains bison (Bison bison bison) and their recovery over the last 125 years is well documented. However, introgression from domestic cattle (Bos taurus) into the few remaining bison populations that existed in the late 1800s has now been identified in many modern bison herds. We examined the phenotypic effect of this ancestry by comparing weight and height of bison with cattle or bison mitochondrial DNA (mtDNA) from Santa Catalina Island, California (U.S.A.), a nutritionally stressful environment for bison, and of a group of age-matched feedlot bison males in Montana, a nutritionally rich environment. The environmental and nutritional differences between these 2 bison populations were very different and demonstrated the phenotypic effect of domestic cattle mtDNA in bison over a broad range of conditions. For example, the average weight of feedlot males that were 2 years of age was 2.54 times greater than that of males from Santa Catalina Island. In both environments, bison with cattle mtDNA had lower weight compared with bison with bison mtDNA, and on Santa Catalina Island, the height of bison with cattle mtDNA was lower than the height of bison with bison mtDNA. These data support the hypothesis that body size is smaller and height is lower in bison with domestic cattle mtDNA and that genomic integrity is important for the conservation of the American plains bison. ©2012 Society for Conservation Biology.
Meyer J.L.,University of Georgia |
Frumhoff P.C.,Union of Concerned Scientists |
Hamburg S.P.,Environmental Defense Fund |
De La Rosa C.,Catalina Island Conservancy
Frontiers in Ecology and the Environment | Year: 2010
Environmental policies and actions can be improved when environmental scientists engage in science-based advocacy, by calling attention to relevant scientific information and ensuring that policies and their implementation are consistent with the best available science. There are many models for scientist-advocates within and outside of advocacy organizations, and the roles they play may vary, depending on career stage. Here, we discuss the challenges and rewards for scientific staff in science-based advocacy organizations, as well as for an academic working with an advocacy organization, as a consultant, collaborator, or member of an advisory board. We identify some best practices for science-based advocacy and encourage the environmental science community to recognize the importance of the scientist-advocate's role in strengthening environmental policy. © The Ecological Society of America.
Dvorak T.M.,Catalina Island Conservancy |
Catalano A.E.,Catalina Island Conservancy |
Matt Guilliams C.,Santa Barbara Botanic Garden
PhytoKeys | Year: 2016
Crocanthemum greenei (B.L.Rob.) Sorrie (Cistaceae), a perennial sub-shrub, was measured as part of a demographic monitoring effort on Santa Catalina Island, California, USA (hereafter, Catalina). Introduced ungulate browsers remain present on Catalina. Consequently, many palatable plant taxa on the island are subject to and putatively limited by top-down browsing forces. Historically, introduced ungulates have also been present on each island throughout the range of C. greenei. Habitat conservation work, resulting in the construction of ungulate exclosures on Catalina, has now allowed us to measure individuals in their mature, non-browsed form. The published value for C. greenei stem (height) is usually 15-30 cm. While the original description hints at a greater potential size, recent descriptions appear to be influenced by observations made during the decades when plants would have been impacted by introduced ungulate herbivores. Here we present stem measurements of 81 adult individuals, with a median of 49 cm and an interquartile range of 42-56 cm. These measurements suggest an expanded stem (height) range of 15-60 cm better describes the taxon and shed light on the historical impacts of invasive ungulates across the islands and those continuing on Catalina. © Tyler M. Dvorak et al.
Dvorak T.M.,Catalina Island Conservancy |
Catalano A.E.,Catalina Island Conservancy
Ecology and Evolution | Year: 2016
The presence of extra-local invaders, such as the southern California mule deer (Odocoileus hemionus) on Santa Catalina Island, may contribute to more selective and insidious effects within the unique ecosystems that have evolved in their absence. Studies at the species level may detect effects not noticed in broader, community level vegetation monitoring or help tease apart differences in the level of effect among the various ecological components of an invaded system. In this initial study, we measured the impacts of herbivory by mule deer, a species native to analogous habitats on the adjacent mainland, on size and seed production success for Crocanthemum greenei (island rush-rose), a federally listed sub-shrub that is not present on mainland California. We found deer exclusion resulted in an overall increase in stem measurement of 18.8 cm. Exclosure populations exhibited complete seed production success, whereas control populations showed significantly reduced success and exhibited complete failure within 58% of populations. These results show that the introduced mule deer on Santa Catalina Island are negatively affecting a federally threatened plant species. This strongly implies that the current deer management strategy is insufficient, if one of its goals is biodiversity and endemic species conservation. © 2016 Published by John Wiley & Sons Ltd.