Genetic and behavioural evidence of monogamy in a mammal,Kirk's dik-dik (Madoqua kirkii).

Little is known about the mating behaviour of monogamous mammals. Here, we present behavioural and genetic evidence of fidelity in a socially monogamous dwarf antelope, Kirk''s dik-dik. DNA microsatellite analysis revealed no evidence of extra-pair paternity (EPP) in dik-diks: mothers'' partners matched the paternal genotype in all 12 juveniles tested. One likely reason for the absence of EPP is that males guard their mates closely during oestrus and over-mark all female scent, thereby reducing the likelihood of other males attempting to mate. In addition, males may be limited in their ability to search for extra-pair populations (EPCs) by activities associated with pair-bond maintenance. Year-round, males maintained proximity within pairs, followed their females'' activity patterns, and spent approximately 64% of their time with their partners. However, males did attempt to obtain EPCs when the opportunity arose, and genetic monogamy in dik-diks is probably best explained by the behaviour of females: in contrast to many monogamous female birds, female dik-diks do not appear to seek EPC partners. We propose that females avoid extra-pair males because they are unable to mate with them without instigating a potentially dangerous conflict.     

Acute visceral toxoplasmosis in captive dik-dik (Madoqua guentheri smithi)

Acute toxoplasmosis was diagnosed in 2 captive dik-dik (Madoqua guentheri smithi) in the Houston Zoo. Both animals became ill suddenly and died in spite of supportive therapy. Toxoplasma gondii was identified in tissues of both animals immunohistochemically, and antibodies to T. gondii were found in titers of 1:800 or more in both animals upon examination by the modified agglutination rest. The cause of death was considered to be toxoplasmic pneumonia. This is the first report of toxoplasmosis in M. g. smithi.     

Environmental constraints on the foraging behaviour of a dwarf antelope (Madoqua kirkii)

Dik-diks (Madoqua sp.) inhabit semi-arid regions and experience very different conditions of food availability and quality between wet and dry seasons. By comparing the behaviour of dik-diks between these two seasons, we identified environmental constraints affecting their feeding strategies. In both seasons foraging time was limited by high mid day temperatures. In the wet season a high intake rate compensates for the loss in foraging time, but in the dry season water and protein become limiting. To meet minimum daily water requirements in the dry season dik-diks fed on plant species that they avoided during the wet season. Analysis at the plant species level showed higher species selectivity in the wet season than in the dry season. In a multiple regression analysis food species preferences were best explained by relative abundance and water content in the dry season, and by dry matter content in the wet season. In the wet season the daily dry-matter intake of dik-diks in the field was only about 10% higher than the theoretically predicted minimum for a ruminant of this body weight, while protein and water intake were about 3 times as high. This suggests that the most limiting dietary component in the wet season is energy. In the dry season the daily intake of all dietary components is lower than the theoretical minimum required, and also lower than the values suggested by laboratory studies of dik-diks. This dry season deficit is presumably met from body reserves. Dry season water intake was approximately 30% of the intake observed in laboratory studies indicating that dikdiks are even better adapted to arid conditions than suggested by physiological experiments.     

The ovary of Günther's dik-dik, Madoqua guentheri Thomas

The ovaries of five Günther's dik-dik were investigated using histological techniques. The structure of the ovary and corpus luteum as well as the growth and atresia of the follicles are described.     

Renal excretion of urea in a small east African antelope, the dik-dik (Rhynchotragus kirkii)

1. A study on the renal handling of urea by the dik-dik antelope (Rhynchotragus kirkii) was conducted. 2. Plasma and urine samples were analysed for osmolality, urea and creatinine concentrations during dehydration and intra-ruminal loading of potassium and sodium solutions. 3. The glomerular filtration rate (GFR) of the dik-dik was found to be 182.6 +/- 11.7 ml/min/100 kg body mass. 4. Dehydration was observed to increase tubular urea reabsorption and increase plasma and urine osmolalities, but had no effect on the amount of urea filtered at the glomerulus. 5. Potassium loading increased both GFR and urine flow rate.     

The relationship between rate of oxygen consumption, heart rate and thermal conductance of the dik-dik antelope (Rhynchotragus kirkii) at various ambient temperatures

1. The extent of cardiovascular adjustments to heat and cold were investigated between ambient temperatures of 5 and 45 degrees C by measuring conductance and the rates of oxygen consumption and heart beats. 2. Minimum heart rate was observed at 25 degrees C (114 +/- 9 beats/min). In the heat at 45 degrees C heart rate was observed to increase only slightly (127 +/- 12 beats/min) but in the cold -5 degrees C heart rate nearly doubled that at 25 degrees C. 3. Thermal conductance was on average 0.031 mlO2 (g. hr. degrees C)-1 below 25 degrees C but increased by more than 20 times at 40 degrees C. 4. A positive correlation between heart rate and rate of oxygen consumption was demonstrated below 25 degrees C and the relation may be of practical use.     

Observation of a black‐cheeked waxbill (Brunhilda charmosyna) cleaning a Kirk’s dik‐dik (Madoqua kirkii)

The vast majority of interspecific interactions are competitive or exploitative. Yet, some positive interspecies interactions exist, where one (commensalism) or both (mutualism) species benefit. One such interaction is cleaning mutualisms, whereby a cleaner removes parasites from a client. In this note, we document the novel observation of a black‐cheeked waxbill (Brunhilda charmosyna) appearing to clean a Kirk''s dik‐dik (Madoqua kirkii), at the Mpala Research Centre in Laikipia County, Kenya. The purported cleaning took place for over one minute and is notable firstly for the dik‐dik remaining still for the duration of cleaning and secondly for involving two species that are much smaller than those traditionally involved in bird–mammal cleaning interactions. Unfortunately, no further cleaning events were subsequently observed, raising questions about whether this record was opportunistic or a regular occurrence. Future observations may reveal whether this behavior is widespread and whether it involves other small passerines.     

Estimating density of Kirk’s dik‐dik (Madoqua kirkii Günther), impala (Aepyceros melampus Lichtenstein) and common zebra (Equus burchelli Gray) at Mpala,Laikipia District,Kenya

This study compares two methods of estimating the density of three ungulate species: Kirk’s dik‐dik, impala and common zebra, in a dry savannah ecosystem. Fixed strip width and distance sampling involving direct animal counts were used in parallel, and tested for bias and precision in two habitats. Distance sampling was the method that achieved a better balance between accuracy and precision. The differences in sightability of ungulates, according to body size, colour and habitat characteristics, are taken into account by the distance sampling method, but not by the strip method, which produced, what we suspect are, underestimates of animal density.     

Cytogenetics and reproduction of sheep with multiple centric fusions (Robertsonian translocations)

The significance of centric fusions (Robertsonian translocations) in domestic animals, with special reference to sheep, is reviewed. The mating is described of a further 856 ewes with either a normal chromosome number 2n = 54 or carrying one or more of the three different translocations (centric fusions) t1, t2 and t3 in various heterozygous and homozygous arrangements. Rams which were used in the matings were homozygous for one of the translocation chromosomes (2n = 52), double heterozygotes (2n = 52), triple heterozygotes (2n = 51) or were carriers of 4 translocation chromosomes (2n = 50) and 5 translocation chromosomes (2n = 49). A remarkably even distribution of segregation products was recorded in the progeny of all combinations of translocation ewes x translocation rams in those groups in which sufficient animals were available for statistical analysis. Forty-eight chromosomally different groups of animals were mated. Further, the overall fertility of the translocation sheep, measured by conception rate to first service, lambing percentage and number of ewes which did not breed a lamb, was not significantly different from New Zealand national sheep breeding data. In some groups the poorer reproductive performance could be explained by the age structure of the flock and inbreeding depression, which probably affected the performance of some animals. Sheep with progressively decreasing chromosome numbers, due to centric fusion, 2n = 50, 2n = 49 and 2n = 48, are reported. The 2n = 48 category represents a triple homozygous ewe and a triple homozygous ram and is the first report of the viable evolution of such domestic animals. Less than 1% of phenotypically abnormal lambs were recorded in a total of 1995 progeny born over 10 years. It is now considered that there is little or no evidence to suggest that centric fusions in a variety of combinations affect the total productive fitness of domestic sheep. It is suggested that future research should be more actively directed to understanding their genetic significance.     

Caprinae (Bovidae,Artiodactyla, Mammalia) from the Neogene of Mongolia

Gobiocerus mongolicus Sokolov, 1952, Turcocerus kekemaidengensis Ye Jie et al., 1999; and Hypsodontus sp. were recorded in Miocene deposits of the Valley of Lakes (MN4-MN8) and Oioceros atropatenes (Rodler et Weithofer, 1890) occurred in the Mio-Pliocene (MN11-MN20) of northwestern Mongolia. Gobiocerus, Turcocerus, and Hypsodontus represent the same evolutionary lineage. Thus, Caprinae existed in Central Asia in the Early Miocene. They diverged from the Bovidae at the Oligocene-Miocene boundary. The presence of early bovids in this region suggests that this group could have appeared in Central Asia.     

Amino-acid sequence of gayal hemoglobin (Bos gaurus frontalis, Bovidae)

The amino-acid sequences of the alpha- and beta-chains of gayal hemoglobin have been determined and compared with those of bovine and yak hemoglobins. The gayal alpha-chain differs from the alpha-chains of bovine by 3 amino-acid residues and from yak I alpha- and II alpha-hemoglobins by 4 and 2 residues, respectively. The gayal beta-chain differs from bovine beta A- and beta B-chains by 3 and 4 residues, respectively and from yak beta-chains by 2 residues.     

Hippotraginae (Bovidae,Artiodactyla, Mammalia) from the Late Miocene of Tuva

Fossil remains of Late Miocene (Baode, NMU10-NMU11) horse antelopes from Tuva (Russia) are described, including Tragoreas sp., Protoryx tuvaensis sp. nov. from the Taralyk Cher locality and Quirliqnoria sp. from the Kholu locality. A new species, Protoryx tuvaensis Dmitrieva et Serdyuk, is described. These taxa compose a Late Miocene antelope assemblage of a new eastern geographical point (Russia, Tuva, Baode, NMU10-MN11).     

Reproductive biology of Nilgiri tahr, Hemitragus hylocrius (Mammalia: Bovidae)

The reproductive biology of Nilgiri tahr ( Hemitragus hylocrius ) was studied in Eravikulam National Park, Kerala, India from August 1979 to September 1981.
The rutting season occurred during the monsoon (July and August) and the main birth season was January to mid-February. Gestation was estimated at 179 days.
Three females which lost their first young in 1981 conceived 18 to 21 days post-partum. One female conceived of her second young while the first was 15 days old. The remainder of the individually identified females gave birth to one young (n=40) or none (n=4).
Infant mortality was highest during the first two weeks after birth. Young born during the monsoon also had a high mortality rate (0.50/week).
Oestrus during the rut was discontinuous in 1980 and 1981. Periods of frequent oestrus corresponded with periods of low rainfall with a mean lag time of 4.9 days.
The ultimate factor determining the birth season in Nilgiri tahr appears to be weather. The main birth season is timed so as to minimize thermal stress.
Several proximal factors may be important in stimulating reproductive activity. These include photoperiod, temperature, the presence of males in mixed groups, and nutrition. The photoperiod response is unusual in that Nilgiri thar evidently respond to the abrupt decrease in apparent day length associated with the onset of the monsoon.
The inverse correlation of rainfall and oestrous activity may have been effected through the sudden decrease in thermal stress on the females or heavy rainfall (5.7 cm/day) masking pheromonal stimulation.
The pattern of lactation anoestrus observed in Nilgiri tahr approximates results obtained from some studies of domestic Caprini.
Nilgiri tahr females are presumably able to increase their lifetime reproduction by giving birth twice in one year. However, this strategy seemed counterproductive in 1981 as survival was low for second offspring.     

Early Pleistocene Spiral-Horned Antelopes (Artiodactyla,Bovidae) from the Taurida Cave (Crimea,Russia)

Paleontological Journal - The article describes fossil remains of two spiral-horned antelope species Gazellospira torticornis (Aymard, 1854) and Pontoceros ambiguus Vereschagin, Alexejeva, David et...     

Cytotypes of Andropogon gerardii Vitman (Poaceae): fertility and reproduction of aneuploids

In many North American prairies, populations of Andropogon gerardii Vitman (Poaceae) are composed of hexaploid and enneaploid cytotypes (2 n  = 60, 90), with intermediates occurring occasionally. Under controlled pollination, the two common cytotypes can be crossed, producing progeny with a range of chromosome numbers. In an investigation of fertility and compatibilities of intermediate cytotypes, individuals with chromosome numbers between 60 and 90 were crossed with each other, with the 2 n  = 60 and 90 cytotypes, and with South American Andropogon species having 60 chromosomes. Regardless of cytotype, all A. gerardii plants had some fertility and virtually all crosses produced seeds. Cytotype is only partially predictive of fertility. Inter-specific hybrids between A. gerardii and South American hexaploid species were vigorous but sterile. Gene flow in natural A. gerardii populations of mixed cytotype probably involves plants of all cytotypes.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 95–103.     

The Bovidae of Dorn-Dürkheim 1, Germany (Turolian age)

Three bovid species are present at Dorn-Dürkheim 1. The overwhelmingly abundant species is a boselaphine, Miotragocerus sp., with smaller and less advanced teeth than Tragoportax amalthea from Pikermi, Greece. Miotragocerus was present in the latest middle Miocene and Vallesian of western and central Europe and survived into the Turolian. The other two bovid species remain enigmatic and of uncertain tribal affiliation. Each is represented by very few teeth, none of them associated. One species is larger and the other smaller than the Miotragocerus sp. Mesowear analysis of M²s and M³s was used to investigate the dietary regime of Miotragocerus sp. from Dorn-Dürkheim 1. Miotragocerus was found to be linked to extant browsing ungulates close to the transition to mixed feeders. The percentage of abrasive food components like grass in the diet of this species was probably close to 10%. This ratio suggests Miotragocerus is intermediate between the two hipparionine horse species of this early Turolian (MN11) palaeoenvironment.