Unveiling the Fecal Microbiota in Two Captive Mexican Wolf (Canis lupus baileyi) Populations Receiving Different Type of Diets

The Mexican wolf (Canis lupus baileyi) was once distributed in southern United States and northern Mexico. It is an endangered subspecies detached from the gray wolf, and likely exemplifies one of the original migration waves of C. lupus into the new world. This is a canine whose individuals survive in specialized facilities, zoos, and museums as part of captive-breeding programs. In order to contribute to the improvement of the management of this species and favor its long-term conservation in Mexico, we aimed to evaluate the diversity and abundance of the fecal bacterial microbiota in two populations exposed to different types of diet: (1) Michilia (23° N, 104° W); kibble daily and raw meat sporadically, and (2) Ocotal (19° N, 99° W); raw meat daily and live animals periodically. Next generation sequencing (V3-V4 16S rRNA gene) by Illumina was implemented. The operational taxonomic units (OTUs) in Michilia resulted in 9 phyla, 19 classes, 34 orders, 61 families, 204 genera, and 316 species, while in Ocotal there were 12 phyla, 24 classes, 37 orders, 69 families, 232 genera, and 379 species. Higher estimated Chao1 richness, Shannon diversity, and core microbiota were observed in Ocotal. Differences (p < 0.05) between populations occurred according to the Bray–Curtis beta diversity index. In the Michilia, dominance of bacteria that degrade carbohydrates (Firmicutes, Lachnospiraceae, Blautia, Clostrodium, Eisenbergiella, Romboutsia, and Ruminococcus) was observed; they are abundant in kibble diets. In contrast, the Ocotal microbiota was dominated by protein-degrading bacteria (Fusobacteria, Fusobacteriaceae, and Fusobacteria), indicating a possible positive relation with a raw meat diet. The information generated in this study is fundamental to support the implementation of better management plans in the two populations considered here, as well as in different facilities of southern United States and Mexico, where this subspecies is kept in captivity for conservation purposes.

Evaluating how lethal management affects poaching of Mexican wolves

Despite illegal killing (poaching) being the major cause of death among large carnivores globally, little is known about the effect of implementing lethal management policies on poaching. Two opposing hypotheses have been proposed in the literature: implementing lethal management may decrease poaching incidence (killing for tolerance) or increase it (facilitated illegal killing). Here, we report a test of the two opposed hypotheses that poaching (reported and unreported) of Mexican grey wolves ( Canis lupus baileyi ) in Arizona and New Mexico, USA, responded to changes in policy that reduced protections to allow more wolf-killing. We employ advanced biostatistical survival and competing risk methods to data on individual resightings, mortality and disappearances of collared Mexican wolves, supplemented with Bayes factors to assess the strength of evidence. We find inconclusive evidence for any decreases in reported poaching. We also find strong evidence that Mexican wolves were 121% more likely to disappear during periods of reduced protections than during periods of stricter protections, with only slight changes in legal removals by the agency. Therefore, we find strong support for the ‘facilitated illegal killing’ hypothesis and none for the ‘killing for tolerance’ hypothesis. We provide recommendations for improving the effectiveness of US policy on environmental crimes, endangered species and protections for wild animals. Our results have implications beyond the USA or wolves because the results suggest transformations of decades-old management interventions against human-caused mortality among wild animals subject to high rates of poaching.

Evaluating how lethal management affects poaching of Mexican wolves

Despite illegal killing (poaching) being the major cause of death among large carnivores globally, little is known about the effect of implementing lethal management policies on poaching. Two opposing hypotheses have been proposed in the literature: implementing lethal management may decrease poaching incidence (‘killing for tolerance’) or increase it (‘facilitated illegal killing’). Here, we report a test of the two opposed hypotheses that poaching (reported and unreported) of Mexican grey wolves (Canis lupus baileyi) in Arizona and New Mexico, USA, responded to changes in policy that reduced protections to allow more wolf-killing. We employ advanced biostatistical survival and competing-risk methods to data on individual resightings, mortality and disappearances of collared Mexican wolves, supplemented with Bayes Factors to assess strength of evidence. We find inconclusive evidence for any decreases in reported poaching. We also find strong evidence that Mexican wolves were 121% more likely to disappear during periods of reduced protections than during periods of stricter protections, with only slight changes in legal removals by the agency. Therefore, we find strong support for the ‘facilitated illegal killing’ hypothesis and none for the ‘killing for tolerance’ hypothesis. We provide recommendations for improving the effectiveness of US policy on environmental crimes, endangered species, and protections for wild animals. Our results have implications beyond the USA or wolves because the results suggest transformations of decades-old management interventions against human-caused mortality among wild animals subject to high rates of poaching.

Gamete cryopreservation in the recovery program of Mexican gray wolf (Canis lupus baylei): Results of reproductive season of 2018 in Mexico

The Mexican grey wolf (Canis lupus baileyi) is a subspecies of grey wolf with unique morphologic, genetic and historical features. The Mexican grey wolf faced near-extinction during the 70s after decades of predator eradication actions. A binational, United States-Mexico, ex situ management program relying primarily on zoos has enabled a slow recovery for the population. The current population includes approximately two hundred fifty animals in captivity and more than a hundred that have been returned to the wild. One of the components of the recovery program is cryobanking gonadal tissue: initially sperm, and more recently, ovaries and oocytes. During the reproductive season of 2018 our Mexican team cryopreserved sperm obtained by electrojaculation from five males maintained in three facilities (Zoológico San Juan de Aragón, Parque Zoológico de León and Zoológico El Ocotal) and vitrified oocytes and cryopreserved ovaran tissue obtained by ovariohysterectomy in a female maintained at Zoológico de Zacango. Improved methods were introduced, such as the use of a commercial dog sperm extender that enabled superior post-thaw survival and motility rates, the measurement of testosterone and the use of ovary and oocyte cryopreservation techniques based on human procedures. We report the the successful cryopreservation of Mexican grey wolf gametes based only in local resources and expertise contributing, which will impact the population management program’s long-standing efforts to recover a flagship species of Mexican natural richness, the grey wolf. KeywordsBiobank, Oocyte vitrification, ovary cryopreservation, sperm freezing, testis, vitrification. ResumenEl lobo mexicano (Canis lupus baileyi) es una subespecie del lobo gris con características morfológicas, genéticas e históricas únicas. El lobo gris mexicano estuvo cerca de la extinción durante los años 70 después de décadas de acciones para la erradicación de predadores. El programa binacional Estados Unidos-México de manejo ex situ, dependiente principalmente de los zoológicos, ha provisto de una recuperación lenta de la población actualmente con aproximadamente doscientos cincuenta animales en cautiverio y más de una centena de regreso a la vida libre. Uno de los componentes del programa de recuperación es la criopreservación de tejido gonadal, inicialmente espermatozoides y más recientemente ovario y ovocitos. Durante la temporada reproductiva 2018 nuestro equipo en México criopreservó espermatozoides obtenidos por electroeyaculación en tres instituciones (Zoológico San Juan de Aragón, Parque Zoológico de León y Zoológico El Ocotal) y vitrificó ovocitos y criopreservó tejido ovárico después de una ovariohisterectomía en una hembra mantenida en el Zoológico de Zacango. Métodos mejorados fueron introducidos, como el uso de un diluyente comercial para perros con mejores resultados en las tasas de viabilidad y motilidad postcongelación, y el uso de técnicas de criopreservación para ovarios y ovocitos basadas en procedimientos para humanos. Reportamos la criopreservación exitosa de gametos basados solamente en recursos y conocimiento local que impactaran en el programa de manejo de la población con acciones importantes en los esfuerzos de recuperación de una especie emblemática de la riqueza natural mexicana como el lobo gris mexicano.Palabras claveBiobanco, congelación de esperma, criopreservación de ovario, vitrificación de ovocitos, testículos, vitrificación.