Black Wolf Research Articles

Response to technical comment by Muir (2022) on "Negative-assortative mating for color in wolves".

There are very few well-documented examples of negative-assortative mating in vertebrates (see Hedrick et al. [2016] for summaries). The example of negative-assortative mating between gray and black wolves in Yellowstone National Park appears to be the only documented example of negative-assortative mating in mammals and the only documented example in vertebrates for a naturally occurring, single gene, color polymorphism. Muir (2022) has suggested that the partial negative-assortative mating model that Hedrick et al. (2016) used to investigate matings of wolves with different coat colors in Yellowstone is incorrect. Below I show that the model Muir (2022) suggests gives incorrect results and that the model that Hedrick et al. (2016) used is appropriate and that it is analogous to models for selection for other fitness components. For the Yellowstone wolves, the only matings that are between different colors are gray × black matings. From Hedrick et al. (2016), these matings occur with a frequency of 2AP(H + Q) where A and 1 – A are the proportions of negative-assortative and random matings in the population, respectively, assuming that reciprocal matings are equally likely to occur. It is assumed that the recessive kk gray wolves have a frequency of P, the heterozygous Kk black wolves have a frequency of H, and the KK black wolves have a frequency of Q. Notice that the proportion of negative-assortative mating A does not vary but is weighted by the product of the frequencies of the potentially phenotypically different mates. The total frequency of both negative-assortative and random gray × black matings (kk × K−) (and its reciprocal hereafter) is 2AP(H + Q) + 2P(H + Q)(1 − A) = 2P(H + Q) (Table 1). The frequency of gray × gray matings (kk × kk), all of which are from the random-mating proportion of matings, is P2(1 − A) and the frequency of black × black matings (K− × K−), also all of which are from the random-mating proportion, is (H + Q)2(1 − A) (Table 1).

Disease outbreaks select for mate choice and coat color in wolves.

We know much about pathogen evolution and the emergence of new disease strains, but less about host resistance and how it is signaled to other individuals and subsequently maintained. The cline in frequency of black-coated wolves (Canis lupus) across North America is hypothesized to result from a relationship with canine distemper virus (CDV) outbreaks. We tested this hypothesis using cross-sectional data from wolf populations across North America that vary in the prevalence of CDV and the allele that makes coats black, longitudinal data from Yellowstone National Park, and modeling. We found that the frequency of CDV outbreaks generates fluctuating selection that results in heterozygote advantage that in turn affects the frequency of the black allele, optimal mating behavior, and black wolf cline across the continent.

Optimization of Harmonics in Novel Multilevel Inverter using Black Wolf and Whale Optimization algorithms

High-quality electrical energy is the most needed thing for standard living. We use power electronics converters for the conversion of different forms of electrical energy and we use them for producing quality power output. We use semiconductor devices as switches in the process of conversion of DC-DC, AC-DC, AC-AC, and DC-AC according to the requirement of the system. In this paper, an attempt is made to analyze the quality of output power from a multilevel inverter which is used in the conversion of DC supply to AC output voltage. Production of quality power by optimizing the multilevel inverter switching using Whale Optimization Algorithm helps the proposed inverter topology to perform well. The suggested topology and the optimization technique will help in harvesting multiple renewable energy sources with improved quality of power. Different DC sources of different voltage levels could be connected in input and the resultant AC output has less ripple content as per the IEEE standard. A detailed comparison has been made to show the superiority of the proposed algorithm.

Preserving a tradition, while conserving Ladakh’s black wolves

Preserving a tradition, while conserving Ladakh’s black wolves

Carnivores in color: pelt color patterns among carnivores in Idaho

Abstract Pelt color serves many functions from signaling to crypsis to thermoregulation and its purpose has been a lively source of debate in biology for over a century. Determining the effects of both habitat and human influences on pelt color patterns can be difficult. We made novel use of a multispecies occupancy model by defining “pelt color” as “species.” We then used this model to test predictions and estimate pelt color patterns concurrently for three carnivore species in Idaho, United States. We predicted pelt patterns of all three carnivores would be affected by environmental variables as well as human disturbance. Areas of Idaho where baiting was allowed and preferential harvest possible did not explain pelt patterns in black bears and neither did forest cover. Road density was positively associated with detection probability but negatively associated with occupancy of both black and brown pelt bears, however. Gray pelt wolves were found more often in areas with higher road densities than black wolves. As predicted, black, but not gray, wolves were positively associated with forest cover. Both red and black pelt foxes were positively associated with increasing elevation and road density. Black pelt foxes were negatively associated with forest cover, mirroring the habitat use described for native black pelt foxes. We demonstrate how using noninvasively collected data and extending multispecies occupancy models can allow biologists to study the distribution of different pelt colors in wild populations.

Geographic distribution patterns of melanistic Arabian Wolves, Canis lupus arabs (Pocock), in Saudi Arabia (Mammalia: Carnivora)

Melanism is a common colour polymorphism in carnivores, and may have adaptive relevance in certain ecological scenarios. This coat colour variation is present in Arabian Wolves Canis lupus arabs, a widely distributed species in the Arabian Peninsula, especially in western Highlands of Saudi Arabia. Data collection involved field surveys conducted between 2010 and 2017 including active searches for black wolf carcasses, records of live animals encountered during field surveys, and by using >100 camera traps. Niche models were generated for non-melanistic and melanistic wolves based on environmental predictors aiming to discover geographic patterns of distinct phenotypes distribution in this area. In this study, melanistic wolves were recorded at 12 locations from western highlands ranges. Niche model predicts suitability for melanistic and non-melanistic wolves mainly in western highlands and found that melanistic wolves were encountered in regions where moisture is high, predicting a close relationship between humidity and the presence of black animals.

EPAS1 variants in high altitude Tibetan wolves were selectively introgressed into highland dogs.

BackgroundAdmixture can facilitate adaptation. For example, black wolves have obtained the variant causing black coat color through past hybridization with domestic dogs and have higher fitness than gray colored wolves. Another recent example of the transfer of adaptive variation between the two species has been suggested by the similarity between high altitude Tibetan mastiffs and wolves at the EPAS1 gene, a transcription factor induced in low oxygen environments.MethodsHere, we investigate the directionality of admixture in EPAS1 between 28 reference highland gray wolves, 15 reference domestic dogs, and 21 putatively admixed highland wolves. This experimental design represents an expanded sample of Asian dogs and wolves from previous studies. Admixture was inferred using 17,709 publicly available SNP genotypes on canine chromosome 10. We additionally conducted a scan for positive selection in the highland dog genome.ResultsWe find an excess of highland gray wolf ancestry at the EPAS1 locus in highland domestic dogs, suggesting adaptive introgression from wolves to dogs. The signal of admixture is limited in genomic extent to a small region on chromosome 10, indicating that it is the focus of selection in an oxygen-limited environment.DiscussionOur results suggest that an adaptive variant of EPAS1 in highland wolves was transferred to highland dogs, carrying linked variants that potentially function in hypoxia response at high elevation. The intertwined history of dogs and wolves ensures a unique evolutionary dynamic where variants that have appeared in the history of either species can be tested for their effects on fitness under natural and artificial selection. Such coupled evolutionary histories may be key to the persistence of wild canines and their domesticated kin given the increasing anthropogenic modifications that characterize the future of both species.

Gray wolf harvest in Idaho

ABSTRACTRegulated harvest is a relatively new phenomenon for gray wolves (Canis lupus) in the contiguous United States. Most studies of wolf harvest have been conducted in northern latitudes where wolf populations are large and human densities are low. Insights from wolf harvest in northern North America may not accurately describe wolf harvest in the lower 48 states. I assessed the efficacy of the recently (2009, 2011–2014) reinstated wolf harvest in Idaho, USA, to test whether it was selective for certain characteristics of individual wolves. I predicted that males and females would be harvested at similar rates, pups would be more common in trap than rifle harvest, most harvest would be from trapping, and harvest effort would not decline over time. Additionally, I predicted that black wolves would be selected as trophies and more frequent in rifle than trap harvest. Male wolves were more vulnerable to rifle harvest than females, pups were not more vulnerable to trapping, trapping did not comprise most of the harvest, and effort did not appear to change over time. Lastly, black wolves were not effectively targeted as trophies. I recommend continued monitoring of wolf harvest to further test harvest‐related predictions that provide insights specific to wolves and ecological systems of the conterminous United States. © 2016 The Wildlife Society.

Negative-assortative mating for color in wolves.

There is strong negative-assortative mating for gray and black pelage color in the iconic wolves in Yellowstone National Park. This is the first documented case of significant negative-assortative mating in mammals and one of only a very few cases in vertebrates. Of 261 matings documented from 1995 to 2015, 63.6% were between gray and black wolves and the correlation between mates for color was -0.266. There was a similar excess of matings of both gray males × black females and black males × gray females. Using the observed frequency of negative-assortative mating in a model with both random and negative-assortative mating, the estimated proportion of negative-assortative mating was 0.430. The estimated frequency of black wolves in the population from 1996 to 2014 was 0.452 and these frequencies appear stable over this 19-year period. Using the estimated level of negative-assortative mating, the predicted equilibrium frequency of the dominant allele was 0.278, very close to the mean value of 0.253 observed. In addition, the patterns of genotype frequencies, that is, the observed proportion of black homozygotes and the observed excess of black heterozygotes, are consistent with negative-assortative mating. Importantly these results demonstrate that negative-assortative mating could be entirely responsible for the maintenance of this well-known color polymorphism.

Making My Pitch: A Woman’s Baseball Odyssey by Ila Borders, Jean Hastings Ardell

Reviewed by: Making My Pitch: A Woman’s Baseball Odyssey by Ila Borders, Jean Hastings Ardell Ron Briley Ila Borders with Jean Hastings Ardell, Making My Pitch: A Woman’s Baseball Odyssey. Lincoln: University of Nebraska Press, 2017. 224 pp. Cloth, $26.95. Ila Borders, who pursued her baseball dream by peaching collegiately in California and professionally in the independent Northern League, is a courageous young woman whose contributions to the game should enjoy more widespread acknowledgment by baseball fans. The memoir Making My Pitch which Borders wrote in conjunction with baseball historian Jean Hastings Ardell, author of Breaking into Baseball: Women and the National Game (2005), should help to correct this oversight and render Borders the recognition she so rightly deserves. While Making My Pitch offers plenty of “inside baseball” regarding such topics as pitch selection and how to throw the screwball, what makes this memoir truly outstanding is the courage displayed by Borders in addressing such difficult topics as a dysfunctional family, religion, sexual identity, love life, sexism in American society, and her life beyond the diamond. While grit, determination, and talent allowed Borders to pursue her baseball dream, she laments that her fears of openly acknowledging a gay sexual orientation endangered her baseball career and limited her pursuit of happiness and companionship. Borders concludes, “I realized I had made the mistake of finding my self-worth in what I did for a living, instead of who I was” (183). This level of insight allows Making My Pitch to extend beyond the baseball diamond and shed considerable light into issues of gender and sexuality within contemporary American society. Borders and Ardell also provide a unique structure for the memoir which focuses upon a July 30, 1998, game started by Borders for the Duluth-Superior Dukes against the Fargo-Moorhead RedHawks following her first professional win a week earlier. The RedHawks were the best hitting team in the Northern League, and for six innings Borders pitched scoreless baseball. The bullpen, however, could not hold back the RedHawks who won the game in extra innings. By stringing together twelve scoreless frames, Borders was at the apex of her professional career, yet there were no invitations to spring training or a tryout offered by any club in Major League Baseball. The six innings against Fargo-Moorhead correspond with chapters on Borders competing in Little League, middle and high school, college, and two seasons in the Northern League with the St. Paul Saints, Duluth-Superior Dukes, and Madison Black Wolf. It is a story of hard work and talent storming the barricades of prejudice in baseball and American society. Borders pursued her dream of a baseball career but at considerable personal cost. [End Page 235] Growing up in a Southern California working-class family, Ila’s interest in baseball was supported by her father, who taught his daughter how to play the game and insisted that Ila focus upon baseball and not be siphoned off into softball. Ila’s relationship with her father was complicated. She appreciated his support and as a high school athlete even played alongside him on male semi-professional baseball teams. He was tough on her, but the father fostered his daughter’s sense of determination. Yet, his discipline often bordered on abuse of Ila and her siblings, and later in her professional career, he appropriated endorsement money that his daughter earned. He also drank heavily and carried on an affair with another woman, doing little to conceal the relationship from Ila’s mother. Ila initially found her mother to be weak, but she was impressed as her mother learned to live on her own and struggled to deal with Ila’s same-sex attraction, a part of Ila’s identity which her father could not seem to recognize. In addition, Ila had to deal with the death of her maternal grandmother who drowned in the family pool while swimming with her granddaughter. The religious family was concerned with Ila’s aggressive behavior during grade school, and for middle school and high school she attended religious private schools. While some teammates and parents believed that it violated Christian principles for a girl to play as an equal on...

Is black coat color in wolves of Iran an evidence of admixed ancestry with dogs?

Melanism is not considered a typical characteristic in wolves of Iran and dark wolves are believed to have originated from crossbreeding with dogs. Such hybrid individuals can be identified with the combined use of genetic and morphological markers. We analyzed two black wolves using a 544 base pairs (bp) fragment of the mtDNA control region and 15 microsatellite loci in comparison with 28 dogs, 28 wolves, and four known hybrids. The artificial neural networks (ANNs) method was applied to microsatellite data to separate genetically differentiated samples of wolves, dogs, and hybrids, and to determine the correct class for the black specimens. Individual assignments based on ANNs showed that black samples were genetically closer to wolves. Also, in the neighbor-joining network of mtDNA haplotypes, wolves and dogs were separated, with the dark specimens located in the wolf branch as two separate haplotypes. Furthermore, we compared 20 craniometrical characters of the two black individuals with 14 other wolves. The results showed that craniometrical measures of the two black wolves fall within the range of wolf skulls. We found no trace of recent hybridization with free-ranging dogs in the two black wolves. Dark coat color might be the result of a natural combination of alleles in the coat-color-determining gene, mutation in the K locus due to past hybridization with free-ranging dogs, or the effect of ecological factors and adaption to habitat conditions.

Heterozygote Advantage in a Finite Population: Black Color in Wolves.

There is a striking color polymorphism for wolves in the Yellowstone National Park where approximately half the wolves are black. The genetic basis for this polymorphism is known, and fitnesses of the genotypes are estimated. These estimates suggest that there is strong heterozygote advantage but substantial asymmetry in the fitness differences of the 2 homozygotes. Theoretically, such fitnesses in a finite population are thought to reduce genetic variation at least as fast as if there were no selection at all. Because the color polymorphism has remained at about the same frequency for 17 years, about 4 generations, we investigated whether this was consistent with the theoretical predictions. Counter to this general expectation of loss, given the initial frequency of black wolves, the theoretical expectation in this case was found to be that the frequency would only decline slowly over time. For example, if the effective population size is 20, then the expected black allele frequency after 4 generations would be 0.191, somewhat less than the observed value of 0.237. However, nearly 30% of the time the expected frequency is 0.25 or greater, consistent with the contemporary observed frequency. In other words and in contrast to general theoretical predictions, because of the short period of time in evolutionary terms and the relatively weak selection at low frequencies, the observed variation and the predicted theoretical variation are not inconsistent.

Detecting Hybridization between Iranian Wild Wolf (Canis Lupus Pallipes) and Free-Ranging Domestic Dog (Canis Familiaris) by Analysis of Microsatellite Markers

The genetic threat due to hybridization with free-ranging dogs is one major concern in wolf conservation. The identification of hybrids and extent of hybridization is important in the conservation and management of wolf populations. Genetic variation was analyzed at 15 unlinked loci in 28 dogs, 28 wolves, four known hybrids, two black wolves, and one dog with abnormal traits in Iran. Pritchard's model, multivariate ordination by principal component analysis and neighbor joining clustering were used for population clustering and individual assignment. Analysis of genetic variation showed that genetic variability is high in both wolf and dog populations in Iran. Values of H(E) in dog and wolf samples ranged from 0.75-0.92 and 0.77-0.92, respectively. The results of AMOVA showed that the two groups of dog and wolf were significantly different (F(ST) = 0.05 and R(ST) = 0.36; P < 0.001). In each of the three methods, wolf and dog samples were separated into two distinct clusters. Two dark wolves were assigned to the wolf cluster. Also these models detected D32 (dog with abnormal traits) and some other samples, which were assigned to more than one cluster and could be a hybrid. This study is the beginning of a genetic study in wolf populations in Iran, and our results reveal that as in other countries, hybridization between wolves and dogs is sporadic in Iran and can be a threat to wolf populations if human perturbations increase.

How the Gray Wolf Got Its Color

The Report “Molecular and evolutionary history of melanism in North American gray wolves” (T. M. Anderson et al. , 6 March, p. [1339][1]) suggests that the KB gene for black coat color was introgressed from dogs ( Canis lupus familiaris ) into North American gray wolves ( C. lupus ). However, the authors fail to consider an alternative hypothesis: The KB gene may have originated in the historic black wolves of eastern North America ( C. niger, C. rufus , and C. lycaon ). The potential for gray wolf and eastern wolf introgressive hybridization ([ 1 ][2]) provides a mechanism to move an eastern wolf–derived variant into C. lupus during the Wisconsin glaciation (11,000 to 18,000 years ago). The only evidence for the KB gene in coyotes is in the range of the eastern wolf where hybridization between the two species ( C. lycaon x latrans ) has occurred ([ 2 ][3]) and not in more western geographies where gray wolves, dogs, and coyotes overlap. These coyote samples, however, were excluded from the analysis of the most recent common ancestor. If the selection hypothesis for black coat color in forested habitats is true, the prevalence of black pelage in the original timber wolves of the eastern temperate forests of Canada and the United States makes the inclusion of eastern wolf specimens critical for assessing the three possible evolutionary histories proposed by Anderson et al. We suggest that a more complete examination of black canids from eastern North America be conducted before conclusions of introgressive hybridization from dogs to gray wolves are drawn. 1. [↵][4] 1. T. Wheeldon, 2. B. N. White , Biol. Lett. 5, 101 (2009). [OpenUrl][5][Abstract/FREE Full Text][6] 2. [↵][7] 1. C. J. Kyle 2. et al ., Conserv. Genet. 7, 273 (2006). [OpenUrl][8][CrossRef][9] [1]: /lookup/doi/10.1126/science.1165448 [2]: #ref-1 [3]: #ref-2 [4]: #xref-ref-1-1 View reference 1 in text [5]: {openurl}?query=rft.jtitle%253DBiology%2BLetters%26rft.stitle%253DBiol%2BLett%26rft.issn%253D1744-9561%26rft.aulast%253DWheeldon%26rft.auinit1%253DT.%26rft.volume%253D5%26rft.issue%253D1%26rft.spage%253D101%26rft.epage%253D104%26rft.atitle%253DGenetic%2Banalysis%2Bof%2Bhistoric%2Bwestern%2BGreat%2BLakes%2Bregion%2Bwolf%2Bsamples%2Breveals%2Bearly%2BCanis%2Blupus%252Flycaon%2Bhybridization%26rft_id%253Dinfo%253Adoi%252F10.1098%252Frsbl.2008.0516%26rft_id%253Dinfo%253Apmid%252F18940770%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [6]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6MTA6InJveWJpb2xldHQiO3M6NToicmVzaWQiO3M6NzoiNS8xLzEwMSI7czo0OiJhdG9tIjtzOjIxOiIvc2NpLzMyNS81OTM2LzMzLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ== [7]: #xref-ref-2-1 View reference 2 in text [8]: {openurl}?query=rft_id%253Dinfo%253Adoi%252F10.1007%252Fs10592-006-9130-0%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: /lookup/external-ref?access_num=10.1007/s10592-006-9130-0&link_type=DOI

Black Wolf of the Family

Black Wolf of the Family

Occurrence of black wolves in the Northern Apennines, Italy

The occurrence of black-coated individuals in wolfCanis lupus Linnaeus, 1758 populations is not surprising itself, but their presence in populations recovering from a severe numerical decline has been considered a possible sign of crossbreeding with the domestic dog. In the northern Apennines (Italy), black wolves occur at a non-negligible frequency. In a 3300 km2 area, 22% of wolves observed and 23% of all dead wolves found were represented by animals with a completely black coat. One ‘black’ wolf belonging to the studied population was analysed by a set of microsatellite loci, and no trace of hybridization was found in its ancestry. This result induced us to consider the occurrence of a black phenotype in this area possibly derived from a natural combination of wolf alleles in coat colour determining genes, and not necessarily as the result of crossbreeding with the domestic form.

Detecting rare introgression of domestic dog genes into wild wolf ( Canis lupus ) populations by Bayesian admixture analyses of microsatellite variation

Hybridization with free-ranging dogs isthought to threat the genetic integrity ofwolves in Europe, although available mtDNA dataevidenced only sporadic cases of crossbreeding.Here we report results of population assignmentand genetic admixture analyses in 107wild-living Italian wolves, 95 dogs including30 different breeds and feral dogs, andcaptive-reared wolves of unknown or hybridorigins, which were genotyped at 18microsatellites. Two Italian wolves showedunusually dark coats (``black wolves''), and oneshowed a spur in both hindlegs (``fifth fingerwolf''), suggesting hybridization. Italianwolves showed significant deficit ofheterozygotes, positive FIS values anddeviations from Hardy-Weinberg equilibrium.Genetic variability was significantlypartitioned between groups, suggesting thatwolves and dogs represent distinct gene pools.Multivariate ordination of individual genotypesand clustering of inter-individual geneticdistances split wolves and dogs into twodifferent clusters congruent with the priorphenotypic classification, but hybrids andwolves of unknown origin were not identifiedfrom genetic information alone. By contrast, aBayesian admixture analysis assigned all theItalian wolves and dogs to two differentclusters, independent of any prior phenotypicinformation, and simultaneously detected theadmixed gene composition of the hybrids, whichwere assigned to more than one cluster.Captive-reared wolves of unknown origin wereprevalently assigned to the Italian wolfpopulation. Admixture analyses showed that one``black wolf'' had mixed ancestry in the dog genepool and could be a hybrid, while the other twowolves with unusual phenotypes were assigned tothe Italian wolf population.

Spider mythology across the world

To the editor, I would like to make some comments on the article by Dr Vetter on idiopathic wounds and spider bites in the November issue of the journal.1 Unfortunately, the mythology of spider bites is not confined to the United States and enjoys considerable publicity across the Pacific in Australia and New Zealand. In Australia, little evidence supports the existence of a spider that causes necrotic ulcers. Loxosceles rufescens has been introduced into a small region in South Australia, but reports of necrotic arachnidism occur in all parts of Australia, and this spider has only been implicated in 2 cases.2 The white-tail spider (Lampona spp) is the spider implicated most commonly in the development of necrotic wounds in Australia; however, only 2 confirmed bite cases are cited in the literature and these patients developed only minor ulcers.3 Other implicated spiders include the black house spider (Badumna insignis) and wolf spiders (family Lycosidae). Sac spiders occur in Australia, but unlike in other parts of the world, they have not been implicated in cases involving necrotic lesions.4 Results of studies of the venoms of Australian spiders are also inconclusive and, if interpreted in the light of clinical evidence, suggest that the venoms of most Australian spiders do not contain clinically significant cytotoxic components.5,6 A recent study showed that compared with the venom of recluse spiders (L rufescens) found in South Australia, the venom of white-tail and black house spiders does not have any sphingomyelinase activity.5 This finding supports the idea that the venoms are not the cause of necrotic ulcers; however, the investigators conclude differently, based on finding sphingomyelinase activity in midgut extractions. Venom research is based on the assumption that these spiders cause necrosis in humans, but scant evidence supports this hypothesis. There are mainly case reports of suspected spider bites or cases where the spider was not caught or correctly identified. Results of larger series of confirmed spider bites do not support the existence of necrotic arachnidism in Australia.7,8,9 In 52 cases of confirmed white-tail (L cylindratalmurina group) spider bites, no necrosis or ulceration developed.9 Despite this, the diagnoses of “white-tail spider bite” and necrotic arachnidism are entrenched in Australian medical culture, and other diagnoses usually are not even entertained. Vetter refers to a case from Australia in which a skin lesion initially identified as a spider bite was eventually found to be caused by a fungal infection, sporotrichosis.10 There are other cases of misdiagnosis of necrotic arachnidism in Australia, including pyoderma gangrenosum,11 Chromobacterium violaceum8 and Mycobacterium ulcerans.12 In my experience, even more common conditions are misdiagnosed, including Herpes zoster, candidiasis, staphylococcal infections, and skin reactions to arthropod bites (usually bullous reactions). Although secondary infections may result from spider bites, this occurrence appears to be uncommon in a series of 371 confirmed spider bites (unpublished data, 2000). I support the author in urging the medical community to investigate necrotic wounds properly and not simply implicate spiders as the cause of ulceration. With no history of spider bite, the diagnosis of necrotic arachnidism should be at the end of a long list of important differential diagnoses of necrotic ulcers. A good history and physical examination may quickly reveal common causes. Investigations should include wound swabs for microbiologic analysis, and for persistent necrotic lesions (over 3 to 4 weeks), a skin biopsy specimen should be sent for histopathologic assessment and appropriate microbiologic cultures (eg, fungal). In most cases, a correct diagnosis will allow the start of appropriate treatment.

Black Wolf: The Life of Ernest Thompson Seton, by Betty Keller

Black Wolf: The Life of Ernest Thompson Seton, by Betty Keller

Black Wolf: The Life of Ernest Thompson Seton by Betty Keller

Black Wolf: The Life of Ernest Thompson Seton by Betty Keller