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Western Lowland Gorilla (western + lowland_gorilla)
Selected AbstractsFlow Cytometric Sorting of Fresh and Frozen-Thawed Spermatozoa in the Western Lowland Gorilla (Gorilla gorilla gorilla)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2005J.K. O'Brien Abstract We adapted flow cytometry technology for high-purity sorting of X chromosome-bearing spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). Our objectives were to develop methodologies for liquid storage of semen prior to sorting, sorting of liquid-stored and frozen-thawed spermatozoa, and assessment of sorting accuracy. In study 1, the in vitro sperm characteristics of gorilla ejaculates from one male were unchanged (P>0.05) after 8 hr of liquid storage at 15°C in a non-egg yolk diluent (HEPES-buffered modified Tyrode's medium). In study 2, we examined the efficacy of sorting fresh and frozen-thawed spermatozoa using human spermatozoa as a model for gorilla spermatozoa. Ejaculates from one male were split into fresh and frozen aliquots. X-enriched samples derived from both fresh and frozen-thawed human semen were of high purity, as determined by fluorescence in situ hybridization (FISH; 90.7%±2.3%, overall), and contained a high proportion of morphologically normal spermatozoa (86.0%±1.0%, overall). In study 3, we processed liquid-stored semen from two gorillas for sorting using a modification of methods for human spermatozoa. The sort rate for enrichment of X-bearing spermatozoa was 7.3±2.5 spermatozoa per second. The X-enriched samples were of high purity (single-sperm PCR: 83.7%) and normal morphology (79.0%±3.9%). In study 4 we examined frozen-thawed gorilla semen, and the sort rate (8.3±2.9 X-bearing sperm/sec), purity (89.7%), and normal morphology (81.4%±3.4%) were comparable to those of liquid-stored semen. Depending on the male and the type of sample used (fresh or frozen-thawed), 0.8,2.2% of gorilla spermatozoa in the processed ejaculate were present in the X-enriched sample. These results demonstrate that fresh or frozen-thawed gorilla spermatozoa can be flow cytometrically sorted into samples enriched for X-bearing spermatozoa. Am. J. Primatol. 66:297,315, 2005. © 2005 Wiley-Liss, Inc. [source] A survey of the apes in the Dzanga-Ndoki National Park, Central African Republic: a comparison between the census and survey methods of estimating the gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) nest group densityAFRICAN JOURNAL OF ECOLOGY, Issue 1 2001A. Blom Abstract A survey of apes was carried out between October 1996 and May 1997 in the Dzanga sector of the Dzanga-Ndoki National Park, Central African Republic (CAR), to estimate gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) densities. The density estimates were based on nest counts. The strip transect census and the line transect survey method (Standing Crop Nest Count) were used to estimate the gorilla nest group density. The strip transect has been most commonly used to date. It assumes that all nest groups within the width of the strip are detected, but as this assumption is easily violated in the dense tropical rain forest, the line transect survey was also used. In this method, only the nest groups on the transect line itself should be detected. This method proved to be an adequate and easy technique for estimating animal densities in dense vegetation. The gorilla density of 1.6 individuals km,2 (line transect survey method) found for the Dzanga sector is one of the highest densities ever reported in the literature for the Western lowland gorilla. The density estimate for chimpanzees was 0.16 individuals km,2 (census method). The results of this study confirm the importance of the Dzanga-Ndoki National Park for primate conservation. Résumé Entre octobre 1996 et mai 1997, on a étudié les grands singes du secteur de Dzanga dans le Parc National de Dzanga-Ndoki, en République Centrafricaine (RCA), pour évaluer les densités de gorilles (Gorilla gorilla gorilla) et de chimpanzés (Pan troglodytes). Les estimations de densité se basaient sur le comptage des nids. On a utilisé le recensement par bande transect et la méthode de contrôle par transect linéaire (comptage réel des nids) pour estimer la densité des groupes de nids de gorilles. C'est la bande transect qui est la plus communément utilisée à ce jour. Cela suppose que l'on détecte tous les groupes de nids inclus dans la largeur de la bande, mais comme cette supposition est facilement mise en défaut dans la forêt tropicale humide dense, on a aussi utilisé la méthode des transects en ligne. Avec cette méthode, seuls les groupes de nids qui sont sur la ligne de transect doivent être détectés. Cette méthode s'est révélée une technique adéquate et facile pour estimer les densités animales dans la végétation dense. La densité des gorilles (1,6 individus / km2) relevée pour le secteur de Dzanga est une des plus élevées jamais reportées dans la littérature pour le Gorille de plaine occidental. On a estimé la densité des chimpanzés à 0,16 individus / km2 (par la méthode de recensement). Les résultats de cette étude confirment l'importance du Parc National de Dzanga-Ndoki pour la conservation des primates. [source] Dental wear, wear rate, and dental disease in the African apesAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2010Alison A. Elgart Abstract The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin,enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin,enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample. Am. J. Primatol. 72:481,491, 2010. © 2010 Wiley-Liss, Inc. [source] Western lowland gorillas (Gorilla gorilla gorilla) change their activity patterns in response to frugivoryAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2009Shelly Masi Abstract The most important environmental factor explaining interspecies variation in ecology and sociality of the great apes is likely to be variation in resource availability. Relatively little is known about the activity patterns of western lowland gorillas (Gorilla gorilla gorilla), which inhabit a dramatically different environment from the well-studied mountain gorillas (G. beringei beringei). This study aims to provide a detailed quantification of western lowland gorillas' activity budgets using direct observations on one habituated group in Bai Hokou, Central African Republic. We examined how activity patterns of both sexes are shaped by seasonal frugivory. Activity was recorded with 5-min instantaneous sampling between December 2004 and December 2005. During the high-frugivory period the gorillas spent less time feeding and more time traveling than during the low-frugivory period. The silverback spent less time feeding but more time resting than both females and immatures, which likely results from a combination of social and physiological factors. When compared with mountain gorillas, western lowland gorillas spend more time feeding (67 vs. 55%) and traveling (12 vs. 6.5%), but less time resting (21 vs. 34%) and engaging in social/other activities (0.5 vs. 3.6%). This disparity in activity budgets of western lowland gorillas and mountain gorillas may be explained by the more frugivorous diet and the greater dispersion of food resources experienced by western lowland gorillas. Like other apes, western lowland gorillas change their activity patterns in response to changes in the diet. Am. J. Primatol. 71:91,100, 2009. © 2008 Wiley-Liss, Inc. [source] Cervical necrotizing fasciitis and myositis in a western lowland gorilla (Gorilla gorilla gorilla)JOURNAL OF MEDICAL PRIMATOLOGY, Issue 3 2009M.C. Allender Abstract A 39-yr-old wild-caught, female western lowland gorilla (Gorilla gorilla gorilla) died during an immobilization to assess swelling and apparent pain of the cervical region. Necropsy revealed a fistulous tract containing plant material in the oropharynx, above the soft palate, communicating with a left-sided cervical necrotizing fasciitis and myositis. Alpha-hemolytic Streptococcus and Prevotella sp. were isolated from the cervical lesion. This is a report of cervical necrotizing fasciitis in a western lowland gorilla. [source] Behavioral responses of one western lowland gorilla (Gorilla gorilla gorilla) group at Bai Hokou, Central African Republic, to tourists, researchers and trackersAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2010Michelle Klailova Abstract Gorilla tourism, widely perceived as a lucrative industry, is propelled by strong market demand with programs in five countries and for three of four gorilla subspecies. Human presence may negatively affect wild gorillas, potentially lowering immunity and increasing the likelihood of acquiring human-borne disease. Yet, behavioral impacts of humans on wild gorilla behavior remain largely unexplored, particularly for western lowland gorillas. We evaluate the impact of tourist presence, human observer numbers (tourists, trackers, and researchers), and human observer distance on the behavior of one habituated gorilla group at Bai Hokou, Central African Republic. Behavioral data were collected for more than 12 months from January 2007. Of silverback aggressive events, 39% (N=229) were human directed, but 65% were low-level soft barks. Adult females, and one in particular, were responsible for the highest number of aggressive events toward humans. Humans maintained closer proximity to the silverback when tourists were present, although tourist numbers had no significant impact on overall group activity budgets or rates of human-directed aggression. However, as research team size increased, group feeding rates decreased. Close observer,silverback distance correlated with a decrease in his feeding rates and an increase in human monitoring. He directed less aggression toward observers at distances >10,m, although observers spent 48.5% of time between 6 and 10,m of the silverback. We discuss gorilla personality as a factor in human-directed aggression. We explore whether the current 7,m distance limit governing gorilla tourism, based on disease transmission risks, is sufficient considering the potential behavioral stressor of close human presence. We recommend increasing minimum observation distance to >10,m where possible, decreasing observer group sizes, particularly after a visit consisting of maximum numbers and restricting tourist access to 1 visit/day. Am. J. Primatol. 72:897,906, 2010. © 2010 Wiley-Liss, Inc. [source] Hominoid seminal protein evolution and ancestral mating behaviorAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2008Sarah J. Carnahan Abstract Hominoid mating systems show extensive variation among species. The degree of sexual dimorphism in body size and canine size varies among primates in accordance with their mating system, as does the testes size and the consistency of ejaculated semen, in response to differing levels of sperm competition. To investigate patterns of evolution at hominoid seminal proteins and to make inferences regarding the mating systems of extinct taxa, we sequenced the entire coding region of the prostate-specific transglutaminase (TGM4) gene in human, chimpanzee, bonobo, western lowland gorilla, eastern lowland gorilla, orangutan, and siamang, including multiple humans, chimps, and gorillas. Partial DNA sequence of the coding regions was also obtained for one eastern lowland gorilla at the semenogelin genes (SEMG1 and SEMG2), which code for the predominant proteins in semen. Patterns of nucleotide variation and inferred protein sequence change were evaluated within and between species. Combining the present data with previous studies demonstrates a high rate of amino acid substitutions, and low intraspecific variation, at seminal proteins in Pan, presumably driven by strong sperm competition. Both gorilla species apparently possess nonfunctional TGM4, SEMG1, and SEMG2 genes, suggesting that gorillas have had low sperm competition, and therefore their current polygynous mating system, for a long time before their divergence. Similarly, orangutans show longstanding stasis at TGM4, which may be interpreted as evidence for an unchanging mating system for most of their evolution after their divergence from African apes. In contrast to the great apes, the data from humans could be interpreted as evidence of fluctuations between different mating systems or alternatively as a relaxed functional constraint in these proteins. It is our hope that this study is a first step toward developing a model to predict ancestral mating systems from extant molecular data to complement interpretations from the fossil record. Am. J. Primatol. 70:939,948, 2008. © 2008 Wiley-Liss, Inc. [source] Flow Cytometric Sorting of Fresh and Frozen-Thawed Spermatozoa in the Western Lowland Gorilla (Gorilla gorilla gorilla)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2005J.K. O'Brien Abstract We adapted flow cytometry technology for high-purity sorting of X chromosome-bearing spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). Our objectives were to develop methodologies for liquid storage of semen prior to sorting, sorting of liquid-stored and frozen-thawed spermatozoa, and assessment of sorting accuracy. In study 1, the in vitro sperm characteristics of gorilla ejaculates from one male were unchanged (P>0.05) after 8 hr of liquid storage at 15°C in a non-egg yolk diluent (HEPES-buffered modified Tyrode's medium). In study 2, we examined the efficacy of sorting fresh and frozen-thawed spermatozoa using human spermatozoa as a model for gorilla spermatozoa. Ejaculates from one male were split into fresh and frozen aliquots. X-enriched samples derived from both fresh and frozen-thawed human semen were of high purity, as determined by fluorescence in situ hybridization (FISH; 90.7%±2.3%, overall), and contained a high proportion of morphologically normal spermatozoa (86.0%±1.0%, overall). In study 3, we processed liquid-stored semen from two gorillas for sorting using a modification of methods for human spermatozoa. The sort rate for enrichment of X-bearing spermatozoa was 7.3±2.5 spermatozoa per second. The X-enriched samples were of high purity (single-sperm PCR: 83.7%) and normal morphology (79.0%±3.9%). In study 4 we examined frozen-thawed gorilla semen, and the sort rate (8.3±2.9 X-bearing sperm/sec), purity (89.7%), and normal morphology (81.4%±3.4%) were comparable to those of liquid-stored semen. Depending on the male and the type of sample used (fresh or frozen-thawed), 0.8,2.2% of gorilla spermatozoa in the processed ejaculate were present in the X-enriched sample. These results demonstrate that fresh or frozen-thawed gorilla spermatozoa can be flow cytometrically sorted into samples enriched for X-bearing spermatozoa. Am. J. Primatol. 66:297,315, 2005. © 2005 Wiley-Liss, Inc. [source] Behavioral responses of one western lowland gorilla (Gorilla gorilla gorilla) group at Bai Hokou, Central African Republic, to tourists, researchers and trackersAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2010Michelle Klailova Abstract Gorilla tourism, widely perceived as a lucrative industry, is propelled by strong market demand with programs in five countries and for three of four gorilla subspecies. Human presence may negatively affect wild gorillas, potentially lowering immunity and increasing the likelihood of acquiring human-borne disease. Yet, behavioral impacts of humans on wild gorilla behavior remain largely unexplored, particularly for western lowland gorillas. We evaluate the impact of tourist presence, human observer numbers (tourists, trackers, and researchers), and human observer distance on the behavior of one habituated gorilla group at Bai Hokou, Central African Republic. Behavioral data were collected for more than 12 months from January 2007. Of silverback aggressive events, 39% (N=229) were human directed, but 65% were low-level soft barks. Adult females, and one in particular, were responsible for the highest number of aggressive events toward humans. Humans maintained closer proximity to the silverback when tourists were present, although tourist numbers had no significant impact on overall group activity budgets or rates of human-directed aggression. However, as research team size increased, group feeding rates decreased. Close observer,silverback distance correlated with a decrease in his feeding rates and an increase in human monitoring. He directed less aggression toward observers at distances >10,m, although observers spent 48.5% of time between 6 and 10,m of the silverback. We discuss gorilla personality as a factor in human-directed aggression. We explore whether the current 7,m distance limit governing gorilla tourism, based on disease transmission risks, is sufficient considering the potential behavioral stressor of close human presence. We recommend increasing minimum observation distance to >10,m where possible, decreasing observer group sizes, particularly after a visit consisting of maximum numbers and restricting tourist access to 1 visit/day. Am. J. Primatol. 72:897,906, 2010. © 2010 Wiley-Liss, Inc. [source] Sexual behavior in female western lowland gorillas (Gorilla gorilla gorilla): evidence for sexual competitionAMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2009Tara S. Stoinski Abstract Previous research in gorillas suggests that females engage in post-conception mating as a form of sexual competition designed to improve their own reproductive success. This study focused on sexual behaviors in a newly formed group of western lowland gorillas (Gorilla gorilla gorilla) housed at Zoo Atlanta. All females engaged in mating outside their conceptive periods, although there was individual variation in the frequency of the behavior. An analysis of the presence/absence of sexual behavior found females, regardless of reproductive condition, were more likely to engage in sexual behavior on days when other females were sexually active. On these "co-occurrence" days, females were significantly more likely to solicit the silverback, but copulations did not differ from expectation. The results find further evidence for sexual competition among female gorillas and suggest that this may occur throughout their reproductive cycle rather than only during pregnancy. Am. J. Primatol. 71:587,593, 2009. © 2009 Wiley-Liss, Inc. [source] Western lowland gorillas (Gorilla gorilla gorilla) change their activity patterns in response to frugivoryAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2009Shelly Masi Abstract The most important environmental factor explaining interspecies variation in ecology and sociality of the great apes is likely to be variation in resource availability. Relatively little is known about the activity patterns of western lowland gorillas (Gorilla gorilla gorilla), which inhabit a dramatically different environment from the well-studied mountain gorillas (G. beringei beringei). This study aims to provide a detailed quantification of western lowland gorillas' activity budgets using direct observations on one habituated group in Bai Hokou, Central African Republic. We examined how activity patterns of both sexes are shaped by seasonal frugivory. Activity was recorded with 5-min instantaneous sampling between December 2004 and December 2005. During the high-frugivory period the gorillas spent less time feeding and more time traveling than during the low-frugivory period. The silverback spent less time feeding but more time resting than both females and immatures, which likely results from a combination of social and physiological factors. When compared with mountain gorillas, western lowland gorillas spend more time feeding (67 vs. 55%) and traveling (12 vs. 6.5%), but less time resting (21 vs. 34%) and engaging in social/other activities (0.5 vs. 3.6%). This disparity in activity budgets of western lowland gorillas and mountain gorillas may be explained by the more frugivorous diet and the greater dispersion of food resources experienced by western lowland gorillas. Like other apes, western lowland gorillas change their activity patterns in response to changes in the diet. Am. J. Primatol. 71:91,100, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||