Inbreeding and inbreeding depression in endangered red wolves (Canis rufus)

Multiple mechanisms for inbreeding avoidance used simultaneously in a wild ape

Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve.

Kinship composition in mammals

Understanding the evolution of group-living and cooperation requires information on who animals live and cooperate with. Animals can live with kin, non-kin or both, and kinship structure can influence the benefits and costs of group-living and the evolution of within-group cooperation. One aspect of kinship structure is kinship composition, i.e. a group-level attribute of the presence of kin and/or non-kin dyads in groups. Despite its putative importance, the kinship composition of mammalian groups has yet to be characterized. Here, we use the published literature to build an initial kinship composition dataset in mammals, laying the groundwork for future work in the field. In roughly half of the 18 species in our sample, individuals lived solely with same-sex kin, and, in the other half, individuals lived with related and unrelated individuals of the same sex. These initial results suggest that it is not rare for social mammals to live with unrelated individuals of the same sex, highlighting the importance of considering indirect and direct fitness benefits as co-drivers of the evolution of sociality. We hope that our initial dataset and insights will spur the study of kinship structure and sociality towards new exciting avenues.

Runs of homozygosity reveal past bottlenecks and contemporary inbreeding across diverging populations of an island-colonizing bird

Genomes retain evidence of the demographic history and evolutionary forces that have shaped populations and drive speciation. Across island systems, contemporary patterns of genetic diversity reflect population demography, including colonization events, bottlenecks, gene flow and genetic drift. Here, we investigate genome-wide diversity and the distribution of runs of homozygosity (ROH) using whole-genome resequencing of individuals (>22× coverage) from six populations across three archipelagos of Berthelot's pipit (Anthus berthelotii)-a passerine that has recently undergone island speciation. We show the most dramatic reduction in diversity occurs between the mainland sister species (the tawny pipit) and Berthelot's pipit and is lowest in the populations that have experienced sequential bottlenecks (i.e., the Madeiran and Selvagens populations). Pairwise sequential Markovian coalescent (PSMC) analyses estimated that Berthelot's pipit diverged from its sister species ~2 million years ago, with the Madeiran archipelago founded 50,000 years ago, and the Selvagens colonized 8000 years ago. We identify many long ROH (>1 Mb) in these most recently colonized populations. Population expansion within the last 100 years may have eroded long ROH in the Madeiran archipelago, resulting in a prevalence of short ROH (<1 Mb). However, the extensive long and short ROH detected in the Selvagens suggest strong recent inbreeding and bottleneck effects, with as much as 38% of the autosomes consisting of ROH >250 kb. These findings highlight the importance of demographic history, as well as selection and genetic drift, in shaping contemporary patterns of genomic diversity across diverging populations.

From high masked to high realized genetic load in inbred Scandinavian wolves

When new mutations arise at functional sites they are more likely to impair than improve fitness. If not removed by purifying selection, such deleterious mutations will generate a genetic load that can have negative fitness effects in small populations and increase the risk of extinction. This is relevant for the highly inbred Scandinavian wolf (Canis lupus) population, founded by only three wolves in the 1980s and suffering from inbreeding depression. We used functional annotation and evolutionary conservation scores to study deleterious variation in a total of 209 genomes from both the Scandinavian and neighbouring wolf populations in northern Europe. The masked load (deleterious mutations in heterozygote state) was highest in Russia and Finland with deleterious alleles segregating at lower frequency than neutral variation. Genetic drift in the Scandinavian population led to the loss of ancestral alleles, fixation of deleterious variants and a significant increase in the per-individual realized load (deleterious mutations in homozygote state; an increase by 45% in protein-coding genes) over five generations of inbreeding. Arrival of immigrants gave a temporary genetic rescue effect with ancestral alleles re-entering the population and thereby shifting deleterious alleles from homozygous into heterozygote genotypes. However, in the absence of permanent connectivity to Finnish and Russian populations, inbreeding has then again led to the exposure of deleterious mutations. These observations provide genome-wide insight into the magnitude of genetic load and genetic rescue at the molecular level, and in relation to population history. They emphasize the importance of securing gene flow in the management of endangered populations.

Microsatellite Characterization and Panel Selection for Brown Bear (Ursus arctos) Population Assessment

An assessment of the genetic diversity and structure of a population is essential for designing recovery plans for threatened species. Italy hosts two brown bear populations, Ursus arctos marsicanus (Uam), endemic to the Apennines of central Italy, and Ursus arctos arctos (Uaa), in the Italian Alps. Both populations are endangered and occasionally involved in human-wildlife conflict; thus, detailed management plans have been in place for several decades, including genetic monitoring. Here, we propose a simple cost-effective microsatellite-based protocol for the management of populations with low genetic variation. We sampled 22 Uam and 22 Uaa individuals and analyzed a total of 32 microsatellite loci in order to evaluate their applicability in individual identification. Based on genetic variability estimates, we compared data from four different STR marker sets, to evaluate the optimal settings in long-term monitoring projects. Allelic richness and gene diversity were the highest for the Uaa population, whereas depleted genetic variability was noted for the Uam population, which should be regarded as a conservation priority. Our results identified the most effective STR sets for the estimation of genetic diversity and individual discrimination in Uam (9 loci, PIC 0.45; PID 2.0 × 10-5), and Uaa (12 loci, PIC 0.64; PID 6.9 × 10-11) populations, which can easily be utilized by smaller laboratories to support local governments in regular population monitoring. The method we proposed to select the most variable markers could be adopted for the genetic characterization of other small and isolated populations.

Genetic diversity and family groups detected in a coyote population with red wolf ancestry on Galveston Island, Texas

Background

Hybridization can be a conservation concern if genomic introgression leads to the loss of an endangered species’ unique genome, or when hybrid offspring are sterile or less fit than their parental species. Yet hybridization can also be an adaptive management tool if rare populations are inbred and have reduced genetic variation, and there is the opportunity to enhance genetic variation through hybridization. The red wolf (Canis rufus) is a critically endangered wolf endemic to the eastern United States, where all extant red wolves are descended from 14 founders which has led to elevated levels of inbreeding over time. Red wolves were considered extirpated from the wild by 1980, but before they disappeared, they interbred with encroaching coyotes creating a genetically admixed population of canids along coastal Texas and Louisiana. In 2018, a genetic study identified individuals on Galveston Island, Texas with significant amounts of red wolf ancestry. We collected 203 fecal samples from Galveston for a more in-depth analysis of this population to identify the amount of red wolf ancestry present and potential mechanisms that support retention of red wolf ancestry on the landscape.

Results

We identified 24 individual coyotes from Galveston Island and 8 from mainland Texas with greater than 10% red wolf ancestry. Two of those individuals from mainland Texas had greater than 50% red wolf ancestry estimates. Additionally, this population had 5 private alleles that were absent in the North American reference canid populations used in this study, which included 107 southeastern coyotes, 19 captive red wolves, and 38 gray wolves, possibly representing lost red wolf genetic variation. We also identified several individuals on Galveston Island and the mainland of Texas that retained a unique red wolf mitochondrial haplotype present in the red wolf founding population. On Galveston Island, we identified a minimum of four family groups and found coyotes on the island to be highly related, but not genetically depauperate. We did not find clear associations between red wolf ancestry estimates and landscape features, such as open green space or developed areas.

Conclusion

Our results confirm the presence of substantial red wolf ancestry persisting on Galveston Island and adjacent mainland Texas. This population has the potential to benefit future red wolf conservation efforts through novel reproductive techniques and possibly through de-introgression strategies, with the goals of recovering extinct red wolf genetic variation and reducing inbreeding within the species.

Persistence and expansion of cryptic endangered red wolf genomic ancestry along the American Gulf coast

Admixture and introgression play a critical role in adaptation and genetic rescue that has only recently gained a deeper appreciation. Here, we explored the geographical and genomic landscape of cryptic ancestry of the endangered red wolf that persists within the genome of a ubiquitous sister taxon, the coyote, all while the red wolf has been extinct in the wild since the early 1980s. We assessed admixture across 120,621 single nucleotiode polymorphism (SNP) loci genotyped in 293 canid genomes. We found support for increased red wolf ancestry along a west-to-east gradient across the southern United States associated with historical admixture in the past 100 years. Southwestern Louisiana and southeastern Texas, the geographical zone where the last red wolves were known prior to extinction in the wild, contained the highest and oldest levels of red wolf ancestry. Further, given the paucity of inferences based on chromosome types, we compared patterns of ancestry on the X chromosome and autosomes. We additionally aimed to explore the relationship between admixture timing and recombination rate variation to investigate gene flow events. We found that X-linked regions of low recombination rates were depleted of introgression, relative to the autosomes, consistent with the large X effect and enrichment with loci involved in maintaining reproductive isolation. Recombination rate was positively correlated with red wolf ancestry across coyote genomes, consistent with theoretical predictions. The geographical and genomic extent of cryptic red wolf ancestry can provide novel genomic resources for recovery plans targeting the conservation of the endangered red wolf.

Reviving ghost alleles: Genetically admixed coyotes along the American Gulf Coast are critical for saving the endangered red wolf

The last known red wolves were captured in southwestern Louisiana and eastern Texas in 1980 to establish a captive breeding population. Before their extirpation, gene flow with coyotes resulted in the persistence of endangered red wolf genetic variation in local coyote populations. We assessed genomic ancestry and morphology of coyotes in southwestern Louisiana. We detected that 38 to 62% of the coyote genomes contained red wolf ancestry acquired in the past 30 years and have an admixture profile similar to that of the canids captured before the extirpation of red wolves. We further documented a positive correlation between ancestry and weight. Our findings highlight the importance of hybrids and admixed genomes as a reservoir of endangered species ancestry for innovative conservation efforts. Together, this work presents an unprecedented system that conservation can leverage to enrich the recovery program of an endangered species.

Estrous cyclicity and reproductive success are unaffected by translocation for the formation of new reproductive pairs in captive red wolves (Canis rufus)

This study investigated possible female-related causes for inconsistent success among reproductive pairs in the zoo-based red wolf (Canis rufus) population. Females (n = 13) at seven institutions were assessed for evidence of ovulation and normal reproductive cycles through the measurement of estradiol and progesterone metabolite excretion in feces. Fecal cortisol metabolites (FCM) were also measured. Factors potentially affecting FCM and/or estrous cyclicity were recorded, including exhibit status (on vs. off), reproductive history (proven vs. unproven), copulatory behaviors (ties observed: yes or no), pregnancy/parturition (pups or no pups produced), and translocation before the observed breeding season (yes or no). No differences were observed in baseline FCM between females housed on versus off-exhibit (p = .46) or between females producing pups and those who did not (p = .19). Baseline FCM were significantly lower among females observed in copulatory ties compared to females never observed in a tie (p = .04), and tended to be higher in females translocated before the breeding season compared to females in existing reproductive pairs (p = .11), and among historically unproven females compared to proven females (p = .11). All females evaluated had an endocrine profile indicative of ovulation and among the four females translocated to be paired with a new male before the breeding season, two had successful pregnancies, producing litters. Therefore, despite observed differences in baseline FCM among factors, estrous cyclicity and reproductive success are unaffected by translocation for the formation of new reproductive pairs in the zoo-based red wolf population.

A Genome-Wide Perspective on the Persistence of Red Wolf Ancestry in Southeastern Canids

The red wolf (Canis rufus), a legally recognized and critically endangered wolf, is known to interbreed with coyotes (Canis latrans). Declared extirpated in the wild in 1980, red wolves were reintroduced to northeastern North Carolina nearly a decade later. Interbreeding with coyotes was thought to be restricted to a narrow geographic region adjacent to the reintroduced population and largely believed to threaten red wolf recovery. However, red wolf ancestry was recently discovered in canids along the American Gulf Coast, igniting a broader survey of ancestry in southeastern canid populations. Here, we examine geographic and temporal patterns of genome-wide red wolf ancestry in 260 canids across the southeastern United States at over 164 000 SNP loci. We found that red wolf ancestry was most prevalent in canids sampled from Texas in the mid-1970s, although non-trivial amounts of red wolf ancestry persist in this region today. Further, red wolf ancestry was also observed in a subset of coyotes inhabiting North Carolina, despite management efforts to limit the occurrence of hybridization events. Lastly, we found no evidence of substantial red wolf ancestry in southeastern canids outside of these 2 admixture zones. Overall, this study provides a genome-wide survey of red wolf ancestry in canids across the southeastern United States, which may ultimately inform future red wolf restoration efforts.

Effect of inbreeding on the "Club Foot" disorder in Arabian Pureblood horses reared in Italy

Background:

“The Club Foot” (or “Mismatched Foot”) is an acquired or congenital flexural deformity of the distal interphalangeal joint, caused by a shortening of the musculotendinous unit of the deep digital flexor tendon.

Aim:

The aim of this research was to detect the incidence of the disorder in Arabian Pureblood horses, attempting to understand its causes and to analyze a possible role of inbreeding in its expression. In this breed, in fact, the pathology is widespread because in the environment of origin, the rocky desert, a hard and almost goat’s hoof is not disabling so the selection against this disorder has never been done.

Methods:

Pedigrees were taken from 141 (reference population = RP) adult Arabian Pureblood horses (51 males and 90 females) belonging to eight Italian different farms during the period 1982–2017. For each horse, the presence or not of the disorder was observed and inbreeding coefficients (F) was performed. Four grades of deformity were considered. Moreover, the environmental condition of each farm was considered: boxes, paddocks, nutrition, orientation, and hoof care and shoeing. The chi-square test was applied. Analysis of variance (ANOVA) was used to test the differences in the average inbreeding coefficient (F) between affected and healthy animals, between sexes and between shod and unshod animals.

Results:

Two grades of deformity were observed (I and II) which give less severe manifestations, with 28 females and 25 males (37.59% of the examined horses) showing the disorder. No differences between males and females or between shod (38.29%) and unshod (61.70%) were observed. Environmental conditions do not influence the rate of pathology in the different farms, with a prevalence of the disorder ranging from 7.69% up to 100% on farm. The whole population (WP = RP and its genealogy) included 3,355 records subdivided in seven traced generations. One hundred and eighteen out of 141 horses (RP) were inbred (83.69%). The average inbreeding coefficient (F) in the RP was 0.095. Inbreeding coefficient in RP was <0.05 in only 15 horses (12.71% of inbred), whereas it was >0.25 in 28 horses (23.73% of inbred).

Conclusion:

High inbreeding coefficients were observed in all farms and in particularly in affected animals suggesting that high inbreeding coefficients increases the probability that the disorder occurs. Future works may include the study of the hereditability of the character, and the attempt to identify loci associated with the disorder.

Cross-fostering as a conservation tool to augment endangered carnivore populations

Cross-fostering offspring with nonbiological parents could prove useful to augment populations of endangered carnivores. We used cross-fostering to augment captive-born and wild-born litters for the endangered red wolf (Canis rufus). Between 1987 and 2016, 23 cross-fostering events occurred involving captive-born pups fostered into captive litters (n = 8 events) and captive-born pups fostered into wild recipient litters (n = 15 events). Percentage of pups surviving 3 and 12 months was 91.7% for captive-born pups fostered into captive recipient litters. For pups fostered into wild litters, percentage of pups surviving 5 months was &gt; 94% among fostered pups (pups fostered into a wild red wolf litter or replaced a hybrid litter), pups in recipient litters (wild-born litters receiving fostered pups), and pups in control litters (wild-born litters not in a fostering event) when using pups with known fates. Including pups with unknown fates as deaths, percentage of pups surviving 5 months was &gt; 54% among fostered pups, pups in recipient litters, and pups in control litters. Among wild litters, percentage of pups surviving 12 months was &gt; 82% among fostered pups, pups in recipient litters, and pups in control litters when using pups with known fates. Including pups with unknown fates as deaths, percentage of pups surviving 12 months was &gt; 48% among fostered pups, pups in recipient litters, and pups in control litters. Although survival to 12 months was similar among the groups, average life span was different with pups in control litters living 3.3 years, pups in recipient litters living 4.6 years, and fostered pups living 5.6 years. Of fostered pups surviving &gt; 12 months in the wild, 9 animals whelped or sired 26 litters. Cross-fostering was successful at augmenting litter size for red wolves without any deleterious effects on recipient litters, illustrating fostering as a tool for increasing populations of endangered carnivores.

Size-assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

Anthropogenic hybridization of historically isolated taxa has become a primary conservation challenge for many imperiled species. Indeed, hybridization between red wolves (Canis rufus) and coyotes (Canis latrans) poses a significant challenge to red wolf recovery. We considered seven hypotheses to assess factors influencing hybridization between red wolves and coyotes via pair‐bonding between the two species. Because long‐term monogamy and defense of all‐purpose territories are core characteristics of both species, mate choice has long‐term consequences. Therefore, red wolves may choose similar‐sized mates to acquire partners that behave similarly to themselves in the use of space and diet. We observed multiple factors influencing breeding pair formation by red wolves and found that most wolves paired with similar‐sized conspecifics and wolves that formed congeneric pairs with nonwolves (coyotes and hybrids) were mostly female wolves, the smaller of the two sexes. Additionally, we observed that lower red wolf abundance relative to nonwolves and the absence of helpers increased the probability that wolves consorted with nonwolves. However, successful pairings between red wolves and nonwolves were associated with wolves that maintained small home ranges. Behaviors associated with territoriality are energetically demanding and behaviors (e.g., aggressive interactions, foraging, and space use) involved in maintaining territories are influenced by body size. Consequently, we propose the hypothesis that size disparities between consorting red wolves and coyotes influence positive assortative mating and may represent a reproductive barrier between the two species. We offer that it may be possible to maintain wild populations of red wolves in the presence of coyotes if management strategies increase red wolf abundance on the landscape by mitigating key threats, such as human‐caused mortality and hybridization with coyotes. Increasing red wolf abundance would likely restore selection pressures that increase mean body and home‐range sizes of red wolves and decrease hybridization rates via reduced occurrence of congeneric pairs.

No evidence of inbreeding depression in a Tasmanian devil insurance population despite significant variation in inbreeding

Inbreeding depression occurs when inbred individuals experience reduced fitness as a result of reduced genome-wide heterozygosity. The Tasmanian devil faces extinction due to a contagious cancer, devil facial tumour disease (DFTD). An insurance metapopulation was established in 2006 to ensure the survival of the species and to be used as a source population for re-wilding and genetic rescue. The emergence of DFTD and the rapid decline of wild devil populations have rendered the species at risk of inbreeding depression. We used 33 microsatellite loci to (1) reconstruct a pedigree for the insurance population and (2) estimate genome-wide heterozygosity for 200 individuals. Using heterozygosity-fitness correlations, we investigated the effect of heterozygosity on six diverse fitness measures (ulna length, asymmetry, weight-at-weaning, testes volume, reproductive success and survival). Despite statistically significant evidence of variation in individual inbreeding in this population, we found no associations between inbreeding and any of our six fitness measurements. We propose that the benign environment in captivity may decrease the intensity of inbreeding depression, relative to the stressful conditions in the wild. Future work will need to measure fitness of released animals to facilitate translation of this data to the broader conservation management of the species in its native range.

Space Use and Habitat Selection by Resident and Transient Red Wolves (Canis rufus)

Recovery of large carnivores remains a challenge because complex spatial dynamics that facilitate population persistence are poorly understood. In particular, recovery of the critically endangered red wolf (Canis rufus) has been challenging because of its vulnerability to extinction via human-caused mortality and hybridization with coyotes (Canis latrans). Therefore, understanding red wolf space use and habitat selection is important to assist recovery because key aspects of wolf ecology such as interspecific competition, foraging, and habitat selection are well-known to influence population dynamics and persistence. During 2009-2011, we used global positioning system (GPS) radio-telemetry to quantify space use and 3rd-order habitat selection for resident and transient red wolves on the Albemarle Peninsula of eastern North Carolina. The Albemarle Peninsula was a predominantly agricultural landscape in which red wolves maintained spatially stable home ranges that varied between 25 km2 and 190 km2. Conversely, transient red wolves did not maintain home ranges and traversed areas between 122 km2 and 681 km2. Space use by transient red wolves was not spatially stable and exhibited shifting patterns until residency was achieved by individual wolves. Habitat selection was similar between resident and transient red wolves in which agricultural habitats were selected over forested habitats. However, transients showed stronger selection for edges and roads than resident red wolves. Behaviors of transient wolves are rarely reported in studies of space use and habitat selection because of technological limitations to observed extensive space use and because they do not contribute reproductively to populations. Transients in our study comprised displaced red wolves and younger dispersers that competed for limited space and mating opportunities. Therefore, our results suggest that transiency is likely an important life-history strategy for red wolves that facilitates metapopulation dynamics through short- and long-distance movements and eventual replacement of breeding residents lost to mortality.

Mitochondrial DNA Variation in Southeastern Pre-Columbian Canids

The taxonomic status of the red wolf (Canis rufus) is heavily debated, but could be clarified by examining historic specimens from the southeastern United States. We analyzed mitochondrial DNA (mtDNA) from 3 ancient (350-1900 year olds) putative wolf samples excavated from middens and sinkholes within the historic red wolf range. We detected 3 unique mtDNA haplotypes, which grouped with the coyote mtDNA clade, suggesting that the canids inhabiting southeastern North America prior to human colonization from Europe were either coyotes, which would vastly expand historic coyote distributions, an ancient coyote-wolf hybrid, or a North American evolved red wolf lineage related to coyotes. Should the red wolf prove to be a distinct species, our results support the idea of either an ancient hybrid origin for red wolves or a shared common ancestor between coyotes and red wolves.

Effects of anthropogenic mortality on Critically Endangered red wolf Canis rufus breeding pairs: implications for red wolf recovery

Following precipitous population declines as a result of intensive hunting and 20th century predator-control programmes, hybridization of the Critically Endangered red wolf Canis rufus with coyotes Canis latrans posed a significant challenge for red wolf recovery efforts. Anthropogenic mortality and hybridization continue to pose challenges; the increasing number of wolf deaths caused by humans has limited wolf population growth, facilitated the encroachment of coyotes into eastern North Carolina, and affected the formation and disbandment of breeding pairs. We assessed the effects of anthropogenic mortality on Canis breeding units during a 22-year period (1991–2013). Our results show that deaths caused by people accounted for 40.6% of breeding pair disbandment, and gunshots were the primary cause of mortality. Red wolves replaced congeneric breeding pairs > 75% of the time when pairs disbanded under natural conditions or as a result of management actions. Since the mid 2000s anthropogenic mortality has caused annual preservation rates of red wolf breeding pairs to decline by 34%, and replacement of Canis breeders by red wolves to decline by 30%. Our results demonstrate that human-caused mortality, specifically by gunshots, had a strong negative effect on the longevity of red wolf pairs, which may benefit coyotes indirectly by removing their primary competitor. Coyotes are exacerbating the decline of red wolves by pair-bonding with resident wolves whose mates have been killed.

Infectious disease and red wolf conservation: assessment of disease occurrence and associated risks

Infectious diseases pose a significant threat to global biodiversity and may contribute to extinction. As such, establishing baseline disease prevalence in vulnerable species where disease could affect persistence is important to conservation. We assessed potential disease threats to endangered red wolves (Canis rufus) by evaluating regional (southeastern United States) disease occurrences in mammals and parasite prevalence in red wolves and sympatric coyotes (Canis latrans) in North Carolina. Common viral pathogens in the southeast region, such as canine distemper and canine parvovirus, and numerous widespread endoparasites could pose a threat to the red wolf population. The most prevalent parasites in red wolves and sympatric coyotes were heartworm (Dirofilaria immitis), hookworm (Ancylostoma caninum), and Ehrlichia spp.; several red wolves and coyotes were also positive for bacteria causing Lyme disease (Borrelia burgdorferi). Coyotes had a more species-rich parasite community than red wolves, suggesting they could harbor more parasites and act as a disease reservoir. Species identity and sex did not significantly affect parasite loads, but young canids were less likely to have heartworm and more likely to have high levels of endoparasites. Continued disease monitoring is important for red wolf recovery because low levels of genetic variability may compromise the wolves' abilities to combat novel pathogens from closely related species, such as domestic dogs and coyotes.