Treatment of equine sarcoid in seven Cape mountain zebra (Equus zebra zebra)

Equine sarcoid has been diagnosed in endangered Cape mountain zebra (Equus zebra zebra) in at least two game reserves in South Africa, with prevalence as high as 53% in Bontebok National Park. Seven Cape mountain zebras with sarcoids were treated with either surgical excision, 5-fluorouracil, allogenous vaccine, or a combination of 5-fluorouracil and allogenous vaccine. One of the two sarcoids on one of the 5-fluorouracil-treated zebras was left untreated. The microscopic features of the tumors evaluated showed either all or most of the typical epidermal and dermal histologic features of equine sarcoid. The zebras were examined 2 yr posttreatment to determine outcome. All sarcoids had resolved except on the zebra on which one of the sarcoids was left untreated. The efficacy of the three treatment methods in Cape mountain zebra is encouraging.     

Reproductive characteristics of a free-ranging population of Cape mountain zebra (Equus zebra zebra)

In a population of free-ranging Cape mountain zebra, median age at first foaling was 67 months (range 38-105 months), median foaling interval was 25 months (range 13-69 months) and annual foaling rate was 32%. Foaling rates of younger and older mares were similar. Foals were born all year round with a peak corresponding to the rainy season (summer). Conception occurred later in the season when the spring was dry.     

Reproduction in female Hartmann's zebra, Equus zebra hartmannae

Ovaries, fetuses and plasma were collected from zebra mares shot in the Etosha National Park in Namibia between 15 and 25 August 1983. Ovarian weight was affected by reproductive status and most of the non-pregnant mares were anoestrous. The number of follicles varied between individuals and only pro-oestrous/oestrous mares had follicles larger than 20 mm in diameter. The largest follicle in pregnant mares was only 9 mm in diameter. Corpora lutea and corpora albicantia were found in non-pregnant as well as pregnant mares: 4 pregnant mares had only corpora albicantia. The presence of secondary corpora lutea could not be confirmed in any of the pregnant mares. Implantation was estimated to occur at around 73 days of gestation, and most mares (84%) had conceived between November and April. Peripheral concentrations of plasma progesterone during pregnancy varied from 0.5 to 2.4 ng/ml.     

Monitoring and management of the endangered Cape mountain zebra Equus zebra zebra in the Western Cape, South Africa

De Hoop Nature Reserve and a neighbouring conservancy contain the most genetically diverse subpopulation of the Endangered (IUCN) Cape mountain zebra ( Equus zebra zebra Linnaeus 1758). Although vital for the long-term stability of the meta-population, the population had received limited monitoring post-1999. We summarize data obtained during a population monitoring programme established in 2005. Ninety-nine individuals were identified indicating a decline in annual population growth from 6.6% (1995–1999) to 4.5% (1999–2005). The population was male biased and the deficit of females is likely to have prevented additional breeding herd formation resulting in excess nonbreeding males. These animals are currently of limited reproductive value to the meta-population and may be contributing to the decline in reproductive potential at De Hoop by competing for limited resources. One solution may be to translocate 'excess' males to reinforce existing small populations or establish new populations with females from elsewhere provided that a minimum of 78 animals is maintained at De Hoop to limit genetic loss. Population monitoring and effective management strategies for the De Hoop population and the meta-population are vital to ensure the long-term survival of Cape mountain zebra and for the success of other species recovery programmes.     

Age estimation of zebra

A method of zebra age determination, using the decreasing height of Ml in a wear model, was compared with the method of visual assessment of incisor changes as used by Klingel & Klingel (1966). Good agreement between the methods was found.     

斑纹薄鳅(Leptobotia zebra)应该为斑纹沙鳅(Sinibotia zebra)

斑纹薄鳅(Leptobotia zebra)最初是由Wu(1939)描述的一个新种,当时定名为斑纹沙鳅(Botia zebra),后来Chen(1980)根据眼下刺不分叉将其改归为薄鳅属的物种。本研究通过对线粒体DNA细胞色素b基因序列的测定和分析,发现斑纹薄鳅和薄鳅属(除斑纹薄鳅)物种间的平均遗传距离为0.177,和中华沙鳅属物种美丽沙鳅(Sinibotia pulcher)的平均遗传距离仅为0.057。系统发育分析发现斑纹薄鳅并未和薄鳅属的物种聚在一起,而是和中华沙鳅属物种美丽沙鳅聚在一起形成姐妹群。进一步对斑纹薄鳅进行形态学特征检视,发现该物种具有颊部裸露无鳞、颏部具一对纽状突起等中华沙鳅属鱼类的特征,但又具有眼下刺简单不分叉的薄鳅属鱼类的特征。结合分子数据分析的结果,将斑纹薄鳅订正为中华沙鳅属的物种,其命名为斑纹沙鳅(Sinibotia zebra)。另外,对沙鳅科鱼类属的划分标准及形态特征的演化也进行了讨论。     

Testis size and onset of spermatogenesis in Cape mountain zebras (Equus zebra zebra)

Testis mass of adult Cape mountain zebra stallions (mean 70.0 g) was appreciably less than that of other zebra species and domestic horses. The histological appearance of the testes of 11-, 24- and 29-month-old colts was typically prepubertal. Spermatogenic activity of a 4-year-old stallion obtained at the end of summer was at a very low level, while a 4.5-year-old stallion obtained 6 weeks after the winter solstice showed a marked increase in spermatogenesis compared with the 4-year-old. Stallions 6.5-19 years of age collected in different seasons all showed active spermatogenesis.     

Parentage verification of a mountain zebra (Equus zebra hartmannae) using polymorphic microsatellite markers

The Hartmann's mountain zebra (Equus zebra hartmannae) has been classified by the IUCN as a vulnerable species. Approximately 300 individuals, maintained in zoos throughout Europe and the United States of America, are being managed as part of a captive breeding program. An International Studbook is maintained for the Hartmann's mountain zebra at Marwell Zoological Park, UK. Despite the use of a variety of means to identify each individual in a captive herd, confusion sometimes occurs, resulting in the misidentification of an animal. Here we report the first application of DNA typing, using polymorphic microsatellite loci, to resolve a misidentification involving two female Hartmann's mountain zebra. This case demonstrates the way in which genetic tests derived from a related domesticated species may be used as an effective tool for captive management. Further, this case highlights the need to be able to conclusively identify captive individuals and to maintain accurate pedigree information for successful captive management. © 1995 Wiley-Liss, Inc.     

Palaeozoological insights into management options for a threatened mammal: southern Africa’s Cape mountain zebra (Equus zebra zebra)

Aim Promoting population growth of genetically distinct subpopulations of Cape mountain zebra (Equus zebra zebra) is crucial to the survival of the subspecies. Several important Cape mountain zebra reserves are dominated by fynbos vegetation, and population growth is limited by a lack of grassland habitat. A fossil ungulate sequence spanning the last c. 18,000 years is examined to understand the long‐term history of this conservation challenge. Location Boomplaas Cave (BPA), South Africa. Methods The fossil sequence from BPA is examined to reconstruct ungulate community dynamics in relation to climate and vegetation change over the last 18,000 years. Results Ungulates from 18,000 to 12,000 years ago suggest an expansion of open grasslands that supported a grazing ecosystem dominated by an extinct caprine antelope and equid remains attributed to E. zebra and E. quagga. At the onset of the Holocene, the grazing ungulate community disappears and small browsers and mixed feeders dominate the assemblage, indicating the loss of open grassland vegetation. Several open‐habitat grazers go extinct at this time, and Equus persists at much lower abundances. This shift can be explained by global climate change across the Pleistocene–Holocene transition. Main conclusions The fossil sequence supports contemporary observations indicating that access to open grassland is crucial to maintaining large Cape mountain zebra subpopulations. Although fynbos is abundant throughout the historic range of the Cape mountain zebra, fossil evidence suggests that such vegetation is unlikely to support dense populations. It has been suggested that the acquisition of agricultural lands that were historically converted to open grasslands for livestock could promote Cape mountain zebra population growth. Results presented here support this management option, as the open grasslands in these converted landscapes likely approximate the vegetation structure during latest Pleistocene, when grasslands were widespread and grazing ungulates abundant.     

Molecular ecology of zebra mussel invasions

The invasion of the zebra mussel, Dreissena polymorpha, into North American waters has resulted in profound ecological disturbances and large monetary losses. This study examined the invasion history and patterns of genetic diversity among endemic and invading populations of zebra mussels using DNA sequences from the mitochondrial cytochrome oxidase I (COI) gene. Patterns of haplotype frequency indicate that all invasive populations of zebra mussels from North America and Europe originated from the Ponto-Caspian Sea region. The distribution of haplotypes was consistent with invasive populations arising from the Black Sea drainage, but could not exclude the possibility of an origin from the Caspian Sea drainage. Similar haplotype frequencies among North American populations of D. polymorpha suggest colonization by a single founding population. There was no evidence of invasive populations arising from tectonic lakes in Turkey, while lakes in Greece and Macedonia contained only Dreissena stankovici. Populations in Turkey might be members of a sibling species complex of D. polymorpha. Ponto-Caspian derived populations of D. polymorpha (theta = 0.0011) and Dreissena bugensis (one haplotype) exhibited low levels of genetic diversity at the COI gene, perhaps as a result of repeated population bottlenecks. In contrast, geographically isolated tectonic lake populations exhibited relatively high levels of genetic diversity (theta = 0.0032 to 0.0134). It is possible that the fluctuating environment of the Ponto-Caspian basin facilitated the colonizing habit of invasive populations of D. polymorpha and D. bugensis. Our findings were concordant with the general trend of destructive freshwater invaders in the Great Lakes arising from the Ponto-Caspian Sea basin.     

半散放条件下普通斑马的种群特征

<正>普通斑马又称平原斑马(Equus burchelli),隶属于奇蹄目马科,是一种极具观赏价值的大型哺乳动物。广泛分布于非洲,喜欢栖息在平原和草原,随季节和食物迁徙。普通斑马是社会性动物,习惯群体生活,规模较小的群体由1只雄性和2-6只雌性以及它们未成年的子女组成;或是由十几只未成年的雄性普通斑马组成;较大的群体则有几百只,它们通常是由若干个小规模的群体组成。雄性     

Chromosome studies of a donkey-grevy zebra hybrid

Summary Leukocyte and skin cultures of a female hybrid between a donkey and Grevy zebra show a diploid chromosome complement of 48. From this finding it is inferred that the Grevy zebra is characterized by 2n=34 and that such hybrid's regular infertility is analogous to that of mules and hinnies.Barr bodies were present in the tissue-cultured cells and studies with tritiated thymidine show that Barr body and the chromosome set replicate asynchronously. One large element corresponds to the late replicating X of other species and often possesses the morphologic features of a donkey X. At other times it is decidedly more metacentric, a quality tentatively assigned to the Grevy zebra X. Not enough cells could be studied to determine whether random or selective late replication (? inactivation) of one or the other of the sex chromosomes takes place. It is suggested that the study of such hybrids may yield cytologic information concerning the lyon hypothesis.Supported by a Grant from the USPH Service, GM 10210.The authors acknowledge gratefully the assistance of Mrs. Jane Juergens in photographic work.     

Metabolic ageing in individual zebra finches

Oxidative stress is suggested as a contributor to the ageing process. Knowledge of the relationship between age and energy expenditure may contribute to our understanding of ageing patterns, due to the link between oxygen consumption and free radical production. However, studies on basal metabolic rate (BMR) and age have generally been cross-sectional, which may confound estimates of the age effect due to disproportionate mortality (also known as 'selective disappearance'). We therefore performed a longitudinal study of BMR using captive zebra finches (Taeniopygia guttata) up to 5 years of age. BMR declined with age in individuals of both sexes when body mass was controlled for. Males gained mass with age while females did not. There was no evidence for disproportionate mortality with respect to BMR in either sex. To our knowledge, this is the first longitudinal study of avian BMR over such a long proportion of the lifespan of the study species.     

Song discrimination learning in zebra finches

Young male and female zebra finches, Taeniopygia guttata, were tested for their ability to discriminate between the song of their father or tutor and that of another male in two types of preference test, one with a male whose song was dissimilar to that of the father or tutor and one with a male who sang a similar song, on removal from the father, at 4 months and at 6 months of age. Birds that were isolated from their father at 25 days (group A) did not show a preference for their father's song whereas those isolated from the father at 35 days (groups B and C) learnt to prefer their father's song. In addition, group C, which were housed with tutor 1 from 35 to 70 days and with tutor 2 from 4 to 6 months of age, preferred their tutors' songs to those of other males. If one compares the strength of preference in the two types of test, group B showed a weaker preference for the father in tests with the father and a similar male. Further, group C showed a weaker preference in the test with tutor 1 versus a similar male. The possible influence of tutor, sibling and own song on the discrimination of the father's song is discussed, and the results are compared with those for song performance learning. Finally, the mother birds preferred their mate's song.     

Motion camouflage induced by zebra stripes

The functional significance of the zebra coat stripe pattern is one of the oldest questions in evolutionary biology, having troubled scientists ever since Charles Darwin and Alfred Russel Wallace first disagreed on the subject. While different theories have been put forward to address this question, the idea that the stripes act to confuse or ‘dazzle’ observers remains one of the most plausible. However, the specific mechanisms by which this may operate have not been investigated in detail. In this paper, we investigate how motion of the zebra's high contrast stripes creates visual effects that may act as a form of motion camouflage. We simulated a biologically motivated motion detection algorithm to analyse motion signals generated by different areas on a zebra's body during displacements of their retinal images. Our simulations demonstrate that the motion signals that these coat patterns generate could be a highly misleading source of information. We suggest that the observer's visual system is flooded with erroneous motion signals that correspond to two well-known visual illusions: (i) the wagon-wheel effect (perceived motion inversion due to spatiotemporal aliasing); and (ii) the barber-pole illusion (misperceived direction of motion due to the aperture effect), and predict that these two illusory effects act together to confuse biting insects approaching from the air, or possibly mammalian predators during the hunt, particularly when two or more zebras are observed moving together as a herd.