Search for lunar periodicity in the bannertail kangaroo rat (Dipodomys spectabilis)

Abstract

The endogenous activity cycle of the nocturnal bannertail kangaroo rat was investigated. Although bannertail activity is a function of the lunar day as well as the solar day, all ten subjects exhibited free‐running activity periods of solar‐day length; there was no evidence of an endogenous lunar‐day cycle. Animals were provided with a burrow system and a small pseudo‐desert, a laboratory facility in which animal activity data closely resembled measurements taken in the field. Several analytical techniques for quantifying the data were utilized, and one, the mean interval of activity, is recommended to other investigators.     

Conspecific pilferage but not presence affects Merriam's kangaroo rat cache strategy

We investigated the effects of pilferage on caching behaviorin the Merriam's kangaroo rat by manipulating two factors associatedwith pilferage: the presence of a conspecific, and the opportunityfor pilferage. In one experiment we assessed animals in either"Stealer" or "Victim" roles and measured changes in caching,space use, and behavior after caches were pilfered. Victimsshifted from a majority scatter-hoarding to a majority larder-hoardingstrategy after their caches were pilfered by the Stealer. InExperiment 2, we measured changes after exposure to a conspecificwhen there was no pilferage, with or without prior exposureto pilferage from Experiment 1. Merriam's kangaroo rats werevigilant when a conspecific was present, but did not changecache strategy. Prior exposure did not have any major effecton caching or behavior. Food storage is an economic decisionthat is often made by a solitary forager. Our results suggestthat social competition nonetheless influences such economic decisions, even in a nonsocial forager.     

北美CHIHUAHUAN荒漠旗尾更格卢鼠(DIPODOMYS SPECTABILIS)的种群生态学

本文提供了1978—1985年美国亚利桑那州Chihuahuan荒漠旗尾更格卢鼠(Dipodomys spectabilis)种群的密度、体重、繁殖、扩散和寿命的标志重捕资料。较长的寿命、较重的体重、低繁殖力和喜巢行为标志着它的灵活的生活史,这种生活史使该鼠的种群密度适应荒漠环境的变化而变化。本文还比较了与旗尾更格卢鼠共同生活于同一地区的同属物种麦利阿姆更格卢鼠(Merriam's kangaroo rat, Dipodomys merriami)的生活史性状的差异,这些差异使这两个同属物种能利用不同资源或以不同方式利用相同资源,从而保证了它们的共同生存。     

Coccidiosis in wild grey kangaroos

Deaths occurred among wild grey kangaroos (Macropus giganteus) whose habitat was subject to flooding. A sample of the involved juvenile animals was hypoproteinaemic, and extensive haemorrhagic enteritis, associated with the presence of coccidial life cycle stages was found in the small intestine at necropsy. Masses of small schizonts infected cells of the lamina propria; large schizonts occupied clusters of hypertrophied cells; macrogametes and microgametocytes were observed in cells of the lamina propria. The species of coccidia involved could not be determined, although oocysts of Eimeria cunnamullensis and E. kogoni were found in faeces. Overcrowding, food shortage, damp conditions and possibly feed supplementation with hay on the ground were considered probable epizootiological factors contributing to an outbreak of coccidiosis among juvenile animals.     

Multiple paternity in a philopatric rodent: the interaction of competition and choice

Paternity confusion is often suggested as the benefit that femalemammals accrue by mating with multiple males, but genetic advantagesare also possible. Microsatellite-based parentage analyses demonstratethat female banner-tailed kangaroo rats (Dipodomys spectabilis)commonly mate with more than one male; we asked how male andfemale behaviors interact to influence the characteristics ofmales that sire offspring. Specifically, we compared attributes(age, weight, mobility, relatedness, proximity) of the fathersof 229 known-maternity offspring with those of the other malesaccessible to the mothers. Adult males living adjacent to eachfemale attempt to monopolize access to her, and the nearestmale sires a plurality of offspring, but most mothers' youngare fathered by more than one male and littermates are usuallyhalf-sibs. Male proximity and mobility, but not size, influencethe probability of paternity, suggesting a role for competitivemate searching. Females significantly reduce the inbreedingcoefficient of their offspring by mating with males other than(or in addition to) the nearest male. Fathers are less closelyrelated to the mother in years of high density when unrelatedmales are more accessible to the female. Our results favor thegenetic "bet-hedging" hypothesis, whereby females actively butunselectively seek matings with additional males when the malemost likely to win in mate competition is costly to her (inthis case, genetically less compatible). We anticipate thatgenetic bet hedging will be common in species whose femalesare defendable, especially if they are also philopatric.     

Reconstruction of the historical range alters niche estimates in an endangered rodent

Defining historical baselines is critical for species conservation. Under the niche reduction hypothesis, species in decline may be restricted disproportionately from parts of their environmental niche. This bias likely has important implications for modeling species’ distributions if only contemporary occurrences (i.e. post‐range reduction) are used, because suitable habitat will be classified as unsuitable. Unfortunately, robust historical occurrence data is rarely available for sensitive species. In this study, we documented historical locations of the endangered, keystone giant kangaroo rat Dipodomys ingens by examining aerial imagery for burrow mounds. These burrow mounds are readily identifiable and distinguishable from other soil disturbances. We found giant kangaroo rat burrows well outside the currently accepted estimate of their historical distribution. Following the niche reduction hypothesis, we found that giant kangaroo rats have been extirpated from the flattest, hottest, driest parts of their range due to agricultural conversion. This reduction in their realized niche led to significant changes between historical and contemporary models of their distribution. We found that giant kangaroo rats may have occupied up to 56% more habitat historically than currently believed. Our results provide new guidance for managers working on restoration and habitat protection for this ecosystem engineer. This study highlights the critical importance of modeling historical distributions using the entire environmental niche once occupied by species of conservation need.     

Semicircular canal system in early primates

Mammals with more rapid and agile locomotion have larger semicircular canals relative to body mass than species that move more slowly. Measurements of semicircular canals in extant mammals with known locomotor behaviours can provide a basis for testing hypotheses about locomotion in fossil primates that is independent of postcranial remains, and a means of reconstructing locomotor behaviour in species known only from cranial material. Semicircular canal radii were measured using ultra high resolution X-ray CT data for 9 stem primates (“plesiadapiforms”; n = 11), 7 adapoids (n = 12), 4 omomyoids (n = 5), and the possible omomyoid Rooneyia viejaensis (n = 1). These were compared with a modern sample (210 species including 91 primates) with known locomotor behaviours. The predicted locomotor agilities for extinct primates generally follow expectations based on known postcrania for those taxa. “Plesiadapiforms” and adapids have relatively small semicircular canals, suggesting they practiced less agile locomotion than other fossil primates in the sample, which is consistent with reconstructions of them as less specialized for leaping. The derived notharctid adapoids (excluding Cantius) and all omomyoids sampled have relatively larger semicircular canals, suggesting that they were more agile, with Microchoerus in particular being reconstructed as having had very jerky locomotion with relatively high magnitude accelerations of the head. Rooneyia viejaensis is reconstructed as having been similarly agile to omomyids and derived notharctid adapoids, which suggests that when postcranial material is found for this species it will exhibit features for some leaping behaviour, or for a locomotor mode requiring a similar degree of agility.     

Development of Schistosoma mansoni in the laboratory rat analyzed by light and confocal laser scanning microscopy

The kinetic of maturation (schistogram) of Schistosoma mansoni worms grown in laboratory rats was studied by light and confocal laser scanning microscopy. Infected rats with the BH strain were weekly euthanized 3-9 weeks pi. Recovered flukes stained with hydrochloric carmine were preserved as whole-mounts and analyzed by confocal and brightfield microscopy. Worms displayed varying degrees of maturation of the reproductive system at weeks 3-6. Male worms showed complete maturation of the reproductive system at week 6, while female worms completed their maturation at week 7. Males presented few tubercles in tegument in all weeks. Despite the presence of a developing embryo within the ootype, no uterine egg was found. The schistogram in rats follows a pattern similar to that observed in mice hosts.     

Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Differential bacterial counts were made on the intestinal and caecal contents of chickens after inoculation with a standard dose of 320 000 freshly sporulated oocysts of Eimeria brunetti.     

SNS: Adhesive properties, localization requirements and ectodomain dependence in S2 cells and embryonic myoblasts

The body wall muscles in the Drosophila larva arise from interactions between Duf/Kirre and Irregular chiasm C-roughest (IrreC-rst)-expressing founder myoblasts and sticks-and-stones (SNS)-expressing fusion competent myoblasts in the embryo. Herein, we demonstrate that SNS mediates heterotypic adhesion of S2 cells with Duf/Kirre and IrreC-rst-expressing S2 cells, and colocalizes with these proteins at points of cell contact. These properties are independent of their transmembrane and cytoplasmic domains, and are observed quite readily with GPI-anchored forms of the ectodomains. Heterotypic interactions between Duf/Kirre and SNS-expressing S2 cells occur more rapidly and to a greater extent than homotypic interactions with other Duf/Kirre-expressing cells. In addition, Duf/Kirre and SNS are present in an immunoprecipitable complex from S2 cells. In the embryo, Duf/Kirre and SNS are present at points of contact between founder and fusion competent cells. Moreover, SNS clustering on the cell surface is dependent on Duf/Kirre and/or IrreC-rst. Finally, although the cytoplasmic and transmembrane domains of SNS are expendable for interactions in culture, they are essential for fusion of embryonic myoblasts.     

Distinct mechanisms for mRNA localization during embryonic axis specification in the wasp Nasonia

mRNA localization is a powerful mechanism for targeting factors to different regions of the cell and is used in Drosophila to pattern the early embryo. During oogenesis of the wasp Nasonia, mRNA localization is used extensively to replace the function of the Drosophila bicoid gene for the initiation of patterning along the antero-posterior axis. Nasonia localizes both caudal and nanos to the posterior pole, whereas giant mRNA is localized to the anterior pole of the oocyte; orthodenticle1 (otd1) is localized to both the anterior and posterior poles. The abundance of differentially localized mRNAs during Nasonia oogenesis provided a unique opportunity to study the different mechanisms involved in mRNA localization. Through pharmacological disruption of the microtubule network, we found that both anterior otd1 and giant, as well as posterior caudal mRNA localization was microtubule-dependent. Conversely, posterior otd1 and nanos mRNA localized correctly to the posterior upon microtubule disruption. However, actin is important in anchoring these two posteriorly localized mRNAs to the oosome, the structure containing the pole plasm. Moreover, we find that knocking down the functions of the genes tudor and Bicaudal-D mimics disruption of microtubules, suggesting that tudor's function in Nasonia is different from flies, where it is involved in formation of the pole plasm.     

Identification key for European strand-forming house-rot fungi

An identification key for 20 common strand-forming indoor wood decay fungi is given. The key is based on observations of material from affected buildings and on wood samples that have been incubated in the laboratory. The key is with macro- and microscopic photographs.