• Characterization of Prdm9 in equids and sterility in mules

      Steiner, Cynthia C.; Ryder, Oliver A. (2013)
      Prdm9 (Meisetz) is the first speciation gene discovered in vertebrates conferring reproductive isolation. This locus encodes a meiosis-specific histone H3 methyltransferase that specifies meiotic recombination hotspots during gametogenesis. Allelic differences in Prdm9, characterized for a variable number of zinc finger (ZF) domains, have been associated with hybrid sterility in male house mice via spermatogenic failure at the pachytene stage. The mule, a classic example of hybrid sterility in mammals also exhibits a similar spermatogenesis breakdown, making Prdm9 an interesting candidate to evaluate in equine hybrids. In this study, we characterized the Prdm9 gene in all species of equids by analyzing sequence variation of the ZF domains and estimating positive selection. We also evaluated the role of Prdm9 in hybrid sterility by assessing allelic differences of ZF domains in equine hybrids. We found remarkable variation in the sequence and number of ZF domains among equid species, ranging from five domains in the Tibetan kiang and Asiatic wild ass, to 14 in the Grevy’s zebra. Positive selection was detected in all species at amino acid sites known to be associated with DNA-binding specificity of ZF domains in mice and humans. Equine hybrids, in particular a quartet pedigree composed of a fertile mule showed a mosaic of sequences and number of ZF domains suggesting that Prdm9 variation does not seem by itself to contribute to equine hybrid sterility.
    • Chelonian perivitelline membrane-bound sperm detection: A new breeding management tool

      Croyle, Kaitlin E.; Gibbons, Paul; Light, Christine; Goode, Eric; Durrant, Barbara S.; Jensen, Thomas (2016)
      Perivitelline membrane (PVM)-bound sperm detection has recently been incorporated into avian breeding programs to assess egg fertility, confirm successful copulation, and to evaluate male reproductive status and pair compatibility. Due to the similarities between avian and chelonian egg structure and development, and because fertility determination in chelonian eggs lacking embryonic growth is equally challenging, PVM-bound sperm detection may also be a promising tool for the reproductive management of turtles and tortoises....
    • Data gaps and opportunities for comparative and conservation biology

      Conde, Dalia A.; Staerk, Johanna; Colchero, Fernando; da Silva, Rita; Schöley, Jonas; Baden, H. Maria; Jouvet, Lionel; Fa, John E.; Syed, Hassan; Jongejans, Eelke; et al. (2019)
      Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species.
    • Effects of inbreeding and parental incubation on captive breeding success in Hawaiian crows

      Hoeck, Paquita E. A.; Wolak, Matthew E.; Switzer, Richard A.; Kuehler, Cyndi M.; Lieberman, Alan A. (2015)
      We used 17 years of captive breeding records of the Hawaiian crow (Corvus hawaiiensis) to study the effects of individual and parental level of inbreeding on survival through early life…. Our study contributes to evidence that the strength of inbreeding depression is particularly severe in early life traits. It shows that the negative effects of inbreeding on reproductive success should be accounted for even in benign captive environments where survival is maximized and suggests that parental incubation should be favored over artificial incubation in avian captive breeding programs.
    • Estrogenicity of captive southern white rhinoceros diets and their association with fertility

      Tubbs, Christopher W.; Moley, Laura A.; Ivy, Jamie A.; Metrione, Lara C.; LaClaire, Sydney; Felton, Rachel G.; Durrant, Barbara S.; Milnes, Matthew R. (2016)
      …In this study, we investigate the role of dietary phytoestrogens in this reproductive phenomenon by characterizing activation of southern white rhinoceros (SWR) estrogen receptors (ESRs) 1 and 2 by diet items from nine North American institutions and comparing female SWR fertility to total diet estrogenicity. Of the diet items tested, alfalfa hay and soy and alfalfa-based commercial pellets were found to be the most potent activators of SWR ESRs.…
    • Reconsidering the use of soy and alfalfa in southern white rhinoceros diets

      Tubbs, Christopher W.; Durrant, Barbara S.; Milnes, Matthew R. (2017)
      The captive southern white rhinoceros (SWR) population is not currently self-sustaining due to the reproductive failure of captive-born females. Our research into this phenomenon points to chemicals produced by plants common to captive diets, such as soy and alfalfa, as possible causes...
    • Reproductive impacts of endocrine-disrupting chemicals on wildlife species: Implications for conservation of endangered species

      Tubbs, Christopher W.; McDonough, Caitlin E. (2018)
      Wildlife have proven valuable to our understanding of the potential effects of endocrine-disrupting chemicals (EDCs) on human health by contributing considerably to our understanding of the mechanisms and consequences of EDC exposure. But the threats EDCs present to populations of wildlife species themselves are significant, particularly for endangered species whose existence is vulnerable to any reproductive perturbation....
    • Sequential ovulation and fertility of polyoestrus in American black bears (Ursus americanus)

      Himelright, Brendan M.; Moore, Jenna M.; Gonzales, Ramona L.; Mendoza, Alejandra V.; Dye, Penny S.; Schuett, Randall J.; Durrant, Barbara S.; Read, Betsy A.; Spady, Thomas J. (2014)
      American black bears (Ursus americanus) are seasonally polyoestrous and exhibit delayed implantation, which may allow equal and independent fertility of recurrent oestruses of a mating season. We postulated that the luteal inactivity during delayed implantation allows bears to have sequential ovulation during a polyoestrous mating season such that each oestrus of a polyoestrous female will have equivalent fertility, and pregnancy would not preclude subsequent ovulation and superfetation. Controlled mating experiments were conducted on semi-free-ranging female American black bears during three mating seasons, wherein females were bred by different male cohorts in each oestrus. Behavioural observation, vulva score ranking, genetic paternity analysis, gross morphology of ovaries and microscopic morphology of diapaused embryos were used to evaluate the fertility of each subsequent oestrus in polyoestrous females. Oestrus duration, number of successful mounts and median vulva scores were similar between first and subsequent oestruses of the season. Polyoestrus occurred in 81.3% of oestrous females, with a 9.7 ± 5.5 day (mean ± SD) inter-oestrous interval. Sequential ovulation was documented in three polyoestrous females, including one that possessed both a corpus haemorrhagicum and a developed corpus luteum. Among polyoestrous dams, four of nine embryos were conceived in the first oestrus and five of nine in the second oestrus. These results indicate that each oestrus of polyoestrous females is capable of fertility, even if the female is already pregnant from a prior oestrus. Although superfetation was not directly observed in the present study, our results strongly suggest the potential of superfetation in the American black bear and provide novel insight into the complex behavioural and physiological breeding mechanisms of bears. Given that most endangered bear species share similar reproductive traits with American black bears, captive breeding programmes could take advantage of superfetation by mating females with different males at each subsequent oestrus of the season in order to increase the genetic diversity of captive endangered bears.
    • Serum prolactin and testosterone levels in captive and wild brown kiwi (Apteryx mantelli) during the prebreeding, breeding, and incubation periods

      Jensen, Thomas; Jamieson, Sarah E.; Castro, Isabel; Gartrell, Brett; Cockrem, John F.; Durrant, Barbara S. (2019)
      In brown kiwi (Apteryx mantelli), the male is the primary incubator, a trait that is relatively rare among birds. The maintenance of avian incubation behavior is controlled by the protein hormone prolactin (PRL)....
    • Social influences on the estrous cycle of the captive sun bear (Helarctos Malayanus): Sun bear social influences

      Frederick, Cheryl; Hunt, Kathleen; Kyes, Randall; Collins, Darin; Durrant, Barbara S.; Ha, James; Wasser, Samuel K. (2013)
      We examined the potential influences of existing social housing arrangements on captive sun bear female reproductive cycling. Three social conditions were studied: 1.2, 1.1, and 0.2. Fecal hormone metabolites of total estrogens, progestins and glucocorticoids were compared between the three social conditions and were analyzed along with vaginal cytology data in individuals that experienced a change in social condition....