Osmoregulation by Means of a Hitherto Unsuspected Osmoregulatory Organ in Two Grapsid Crabs

Cape sugarbirds, Promerops cafer, preferred certain pro tea bushes as nest-sites. These bushes were characterized by relatively large leaves and dense foliage. Nests were usually placed in the central parts of bushes Nest-sites were shielded from the cold night sky, and were associated with relatively favourable air temperatures and protection from wind in a season of unfavourable weather. Data on microclimate of nest-sites, together with those on heat loss from an incubating sugarbird, were interpreted in relation to nest-site selection as adaptive behaviour promoting breeding success through conservation of energy. Sugarbirds nesting relatively high off the ground and in dense vegetation were considered to be decreasing die risk of exposure to predators.     

Adaptive evolutionary expansion of the ribonuclease 6 in Rodentia

Ribonuclease 6 (RNase6 or RNase K6) is a protein that belongs to a superfamily thought to be the sole verte‐brate‐specific enzyme known for a wide range of physiological functions, including digestion, cytotoxicity, angiogenesis, male reproduction and host defense. In our study, 51 functional genes and 11 pseudogenes were identified from 27 Rodentia species. Intriguingly, in the 3 main lineages of rodents there were multiple RNase6s identified in all species of Ctenohystrica, whereas only a single RNase6 was observed in other Rodentia species examined except for 2 species in the mouse‐related clade. The evolutionary scenario of “birth (gene duplication) and death (gene deactivation)” and gene sorting have been demonstrated in Ctenohystrica. In addition, bursts of positive selection, diversification of isoelectric point and positive net charge have been identified in Ctenohystrica, especially at two key sites that are involved in antimicrobial function. Site Trp30 has undergone positive selection and Ile45 has changed into other residues in Group B and Group C of the Ctenohystrica. Our results demonstrated a complex and intriguing evolutionary pattern of rodent RNase6, and indicated that functional modification may have occurred, which establishes an important theoretical foundation for future functional assays in rodent RNase6.     

Collateral arteries of the aortic arch of the red-rumped agouti (Dasyprocta leporina Linnaeus, 1758)

Detailed knowledge of the arterial system is an important prerequisite when interpreting experimental data in research, as well as in the diagnosis of cardiovascular disease using imaging techniques such as Doppler echocardiography and contrast radiography. Thus, considering the importance of the aortic arrangement, the objective of this study was to describe the collateral arteries of the aortic arch of agoutis in order to establish the standard model, and therefore contribute to studies involving research related to heart disease, and produce information for a more accurate diagnosis in complementary imaging examinations. In this study, 14 adult animals were used, comprising eight males and six females. The vascular system was washed with 0.9% aqueous saline solution and perfused with Neoprene 450 latex coloured with yellow or red pigment, which was subsequently dissected and analysed. One male animal was used for the digital contrast radiography technique perfused with a liquid barium sulphate solution (Bariogel^®) (1 g/ml) and Neoprene 450 latex, both diluted 1/3. The aortic arch of the agouti presented with only the brachiocephalic trunk as collateral branch in all the animals studied. Thus, agouti falls into type 1 for mammalian aortic arch vascular arrangements.     

Population demise and extinction threat of the Angel de la Guarda deer mouse (Peromyscus guardia)

We analyze the status of the Angel de la Guarda deer mouse (Peromyscus guardia), a species endemic to Mexico, based on our own fieldwork, bibliographic records and information from colleagues. This species, with different subspecies on three islands and a population of an undetermined subspecies on a fourth, was apparently common until the mid-1960s. Currently the species is critically endangered, if not already extinct. One of the subspecies and the undetermined population are presumed extinct. Of the two other subspecies, one is at least in critical condition, and the other at least reduced. The demise of the species can be attributed to the introduction of domestic cats. The case of P. guardia is a good example of the vulnerability of other taxa of endemic rodents on islands in the Gulf of California.     

Least speciose among the most speciose: Natural history correlates of monospecific and bispecific genera of Rodentia and Soricomorpha

Monospecific and bispecific genera are of special concern as they represent unique phylogenetic/evolutionary trajectories within larger clades. In addition, as phylogenetically older taxa are supposed to be exposed to higher rarity and extinction risk, monospecific and bispecific genera may be intrinsically more prone to extinction risks than multispecies genera, although extinction risks also depend on the ecological and biological strategy of the species. Here, the distribution across biogeographical zones and the levels of threat to 2 speciose orders of mammals (monospecific and bispecific genera of Rodentia and Soricomorpha) are investigated in order to highlight major patterns at the worldwide scale. In Rodentia, 39.7% of the genera (n = 490) were monospecific and 17.9% were bispecific. In Soricomorpha, 44.4% of the total genera (n = 45) were monospecific and 15% were bispecific. There was a positive correlation between the number of monospecific genera and the total number of genera per family. Peaks of monospecific and bispecific genera richness were observed in Neotropical, Oriental and Afrotropical regions in rodents and in the Palearctic region in soricomorphs. Range size was significantly uneven across biogeographic region in rodents (with larger ranges in Nearctic and Oriental regions and smaller ranges in the Australian region), but there was no difference across biogeographic regions in terms of range size in soricomorphs. Most of the monospecific and bispecific genera occurred in forest habitat in both taxa. The frequency distribution of the monospecific and bispecific genera across IUCN categories did not differ significantly from the expected pattern using the total rodent genera and the multispecies genera.     

Food of the Black-Backed Jackal: A Preliminary Report

A study was made of the food habits of the black-backed jackal Canis mesomelas by analysis of stomach contents. Two hundred and one stomachs were collected between May 1961 and May 1963, most being obtained in the Transvaal. Percentage occurrence and percentage by volume were calculated for the various foods found in 185 stomachs. Vegetable food (excluding grass) occurred in 18 · 9 per cent of the stomachs, vertebrates in 84 · 9 per cent and invertebrates in 47 · 6 per cent. The most frequent food groups were insects (45 · 5 per cent), rodents and birds (both 32 · 4 per cent), carrion (27 · 0 per cent), hoofed domestic stock (17 · 3 per cent), wild vegetable food (16 · 2 per cent), hares (15 · 7 per cent) and antelope (9 · 7 per cent). A large variety of foods was found in individual stomachs.

Volumetrically, vegetable food amounted to 4 · 5 per cent of the diet, animal food made up 95 · 5 per cent, vertebrates 54 · 2 per cent and invertebrates 8 · 2 per cent. By volume, the major food groups were carrion (28 · 7 per cent), domestic stock (18 · 5 per cent), antelope (9 · 7 per cent), hares (9 · 4 per cent), rodents (9 · 0 per cent), insects (8 · 0 per cent) and birds (4 · 5 per cent).

One hundred and five stomachs from male jackals contained an average of 171 · 6 cc. of food while 90 females gave an average of 129 · 3 cc. The average food volume for all stomachs was 150 · 7 cc. Average food volumes were greater in spring and summer than for the autumn-winter period, suggesting a lesser availability of food from March to August. The merits of the two analysis methods used are discussed and the difficulty in identifying carrion is emphasised. Further investigation is necessary for an understanding of the ecological significance of the jackal’s diet and its economic importance to the sheep farmer. The black-backed jackal is a highly omnivorous feeder; although a confirmed sheep-killer at times, it also feeds on many harmful pest species.     

A blind climber: The first evidence of ultrasonic echolocation in arboreal mammals

The means of orientation is studied in the Vietnamese pygmy dormouse Typhlomys chapensis, a poorly known enigmatic semi‐fossorial semi‐arboreal rodent. Data on eye structure are presented, which prove that Typhlomys (translated as “the blind mouse”) is incapable of object vision: the retina is folded and retains no more than 2500 ganglion cells in the focal plane, and the optic nerve is subject to gliosis. Hence, Typhlomys has no other means for rapid long‐range orientation among tree branches other than echolocation. Ultrasonic vocalization recordings at the frequency range of 50–100 kHz support this hypothesis. The vocalizations are represented by bouts of up to 7 more or less evenly‐spaced and uniform frequency‐modulated sweep‐like pulses in rapid succession. Structurally, these sweeps are similar to frequency‐modulated ultrasonic echolocation calls of some bat species, but they are too faint to be revealed with a common bat detector. When recording video simultaneously with the ultrasonic audio, a significantly greater pulse rate during locomotion compared to that of resting animals has been demonstrated. Our findings of locomotion‐associated ultrasonic vocalization in a fast‐climbing but weakly‐sighted small mammal ecotype add support to the “echolocation‐first theory” of pre‐flight origin of echolocation in bats.