Daily and seasonal vertical migration rhythms in Daphnia

1. Clones of Daphnia longispina (O.F.M.), collected from ponds with different levels of predation, were monitored using video techniques in order to test the effects of temperature and visual cues on vertical migration behaviour.
2. Endogenous rhythms were found to have a part in the control of vertical migration in some clones but responses were highly variable.
3. Low temperature caused a marked increase in the amplitude of vertical migration in D. longispina , consistent with field studies.
4. Clones from ponds with fish predators had larger vertical migration amplitudes than clones from ponds with no fish, providing further evidence for the genetic basis of this mechanism.     

Chamber growth in ammonites inferred from colour markings and naturally etched surfaces of Cretaceous vascoceratids from Nigeria

Cretaceous Vascoceras and Jurassic Lytoceras show colour markings and etched surfaces representing original organic membranes between the septa. The main difference between the formation of ammonite and Nautilus chambers involved the continuous secretion of a gelatinous cameral liquid to support the ammonite mantle when it moved forward. The gel containing cyclically secreted membranes. here named pseudosepta, resembled the intra-cameral structures of the cuttlebone in Sepia. Pseudoscpta are attached to the shell wall in pseudosutures (Pseudoloben) which are particularly visible in the saddles of the septal suture and tend to mimic them. Their shape suggests reconstruction of posterior mantle shape during translocation. Drag-bands (Schleppstreifen) are spiral markings formed by the overlapping pseudosepta along the axial traces of the foliole folds. The chamber of ammonites was formed by a locally muscular mantle in a tripartite cycle: (1) the mantle initially remained attached to the saddles of the completed septal suture while muscular tissue within the umbilical lobes was contracted and rapidly reattached to the side of the lateral saddles; (2) the whole mantle subsequently crept forward by secreting a gelatinous matrix which contained telescoped membranes, with an adhesive function on pseudolobc flanks; (3) the mantle almost ceased to move within the sites of future lobules, but expanded and crept on before forming the mural and 'gutter' ridges of the septum. □ Ammonites, chamber growth, vascoceratids, LYTOCERAS, Nigeria.     

Ranking Alaska Moose Nutrition: Signals to Begin Liberal Antlerless Harvests

Abstract: We focused on describing low nutritional status in an increasing moose (Alces alces gigas) population with reduced predation in Game Management Unit (GMU) 20A near Fairbanks, Alaska, USA. A skeptical public disallowed liberal antlerless harvests of this moose population until we provided convincing data on low nutritional status. We ranked nutritional status in 15 Alaska moose populations (in boreal forests and coastal tundra) based on multiyear twinning rates. Data on age-of-first-reproduction and parturition rates provided a ranking consistent with twinning rates in the 6 areas where comparative data were available. Also, short-yearling mass provided a ranking consistent with twinning rates in 5 of the 6 areas where data were available. Data from 5 areas implied an inverse relationship between twinning rate and browse removal rate. Only in GMU 20A did nutritional indices reach low levels where justification for halting population growth was apparent, which supports prior findings that nutrition is a minor factor limiting most Alaska moose populations compared to predation. With predator reductions, the GMU 20A moose population increased from 1976 until liberal antlerless harvests in 2004. During 1997-2005, GMU 20A moose exhibited the lowest nutritional status reported to date for wild, noninsular, North American populations, including 1) delayed reproduction until moose reached 36 months of age and the lowest parturition rate among 36-month-old moose (29%, n = 147); 2) the lowest average multiyear twinning rates from late-May aerial surveys (x = 7%, SE = 0.9%, n = 9 yr, range = 3-10%) and delayed twinning until moose reached 60 months of age; 3) the lowest average mass of female short-yearlings in Alaska (x̄ = 155 ± 1.6 [SE] kg in the Tanana Flats subpopulation, up to 58 kg below average masses found elsewhere); and 4) high removal (42%) of current annual browse biomass compared to 9-26% elsewhere in boreal forests. When average multiyear twinning rates in GMU 20A (sampled during 1960-2005) declined to <10% in the mid- to late 1990s, we began encouraging liberal antlerless harvests, but only conservative annual harvests of 61-76 antlerless moose were achieved during 1996-2001. Using data in the context of our broader ranking system, we convinced skeptical citizen advisory committees to allow liberal antlerless harvests of 600-690 moose in 2004 and 2005, with the objective of halting population growth of the 16,000-17,000 moose; total harvests were 7-8% of total prehunt numbers. The resulting liberal antlerless harvests served to protect the moose population's health and habitat and to fulfill a mandate for elevated yield. Liberal antlerless harvests appear justified to halt population growth when multiyear twinning rates average ≤10% and ≥1 of the following signals substantiate low nutritional status: <50% of 36-month-old moose are parturient, average multiyear short-yearling mass is <175 kg, or >35% of annual browse biomass is removed by moose.     

Rio Grande Wild Turkey Habitat Selection in the Southern Great Plains

ABSTRACT We recorded telemetry locations from 1,129 radiotagged turkeys (Meleagris gallopavo intermedia) on 4 study areas in the Texas Panhandle and southwestern Kansas, USA, from 2000 to 2004. Analyses of telemetry locations indicated both sexes selected riparian vegetative zones. Females did not select grazed or nongrazed pastures for daily movements. However, females did select nongrazed pastures for nest sites on 2 study areas and males selected for grazed pastures at one study area during the breeding season. We compared nest sites (n = 351) to random sites using logistic regression, which indicated height of visual obstruction, percent canopy cover, and percent bare ground provided the highest predictive power (P ≤ 0.003) for characteristics describing nest-site selection. Nest-site vegetative characteristics between vegetative zones differed primarily in composition: upland zone nest sites had more (P ≤ 0.001) shrubs and riparian zone nest sites had more (P ≤ 0.001) grass. There were no differences in measured nest site vegetative characteristics between pasture types, but there were differences between available nesting cover in grazed and nongrazed pastures. Random plots in grazed pastures had less grass cover (P ≤ 0.001) and more bare ground (P = 0.002). Because of cattle impacts on average grass height and availability, grazing would likely have the highest impact on nesting in riparian zones due to turkey use of grass as nesting cover. An appropriate grazing plan to promote Rio Grande turkey nesting habitat would include grazing upland zones in the spring, when it likely has little impact on nesting-site selection, and grazing riparian zones following breeding season completion. Grazing at light to moderate intensities with periods of rest did not affect male turkey pasture use and may have continued to maintain open areas used by male turkeys for displaying purposes.     

Mutable things: colours as material practice in the northwest of South Australia

This article details the material colour practices of An angu (Pitjantjatjara and Yankunytjatjara people) living in the east of the Western Desert, to show how coloured things have been instrumental in remaking their lives post contact with the colonizers. I argue here that ‘colour’ is a cultural invention. Brightly coloured things, such as cloth and paints, were eagerly appropriated by Aboriginal people when these were imported during the colonization of Australia. Material colours, including consumer goods, have become integral to An angu's conception of their own humanity in the contemporary world. For An angu, colours manifest the mutability of things and sequences of colour transformations are states of becoming.

Résumé

L'auteure détaille les pratiques matérielles des couleurs des An angu (peuples Pitjantjatjara et Yankunytjatjara) vivant dans l'est du Désert de l'Ouest pour montrer comment les choses colorées ont joué un rôle crucial pour reconstruire leurs existences après le contact colonial. Elle avance que « la couleur » est une invention culturelle. Les Aborigènes se sont appropriés avec enthousiasme les objets de couleur vive, tissus et peintures par exemple, lorsque ceux‐ci ont été importés pendant la colonisation de l'Australie. Les couleurs matérielles, notamment celles de biens de consommation courante, en sont venues à faire partie intégrante de la conception par les An angu de leur propre humanité dans le monde contemporain. Pour eux, les couleurs manifestent la mutabilité des choses et les séquences de transformations des couleurs sont des états de devenir.     

A new genus from the continental slope off Brazil and the discovery of the first males in the Hirsutiidae (Crustacea: Peracarida: Bochusacea)

Montucaris distincta gen. nov. sp. nov. , a new genus and species of hirsutiid, is described from the bathyal floor of the northern South Atlantic, off Brazil. It is easily distinguished from other members of the family by the reduced, one-segmented exopods of pereopods 5 and 6 and the array of stout triangular spines present on the anterior margin of the basis and proximal endopodal segments of the third pereopod. This discovery is notable as it includes the first record of males in the family, demonstrating that hirsutiids are gonochoristic. Developmental stages including mancas, preparatory females and juvenile males were recovered, in addition to numerous brooding females and two morphs of adult males. We infer that the new genus has a life cycle involving non-feeding terminal males with regressed mouthparts. These males display a bizarre cephalic configuration, with a clearly defined transverse dorsal suture on the dorsal cephalothoracic shield just behind the articulation of mandibles, a feature present also in syncarida and in some Thermosbaenacea and that we interpret as secondary. The peracaridan affinities of the Hirsutiidae are firmly established here after settling definitively the oostegitic nature of the setose plates present on the posteromedial margin of the pereopodal coxae of brooding females. The separate ordinal rank for hirsutiids – as the Bochusacea – with respect to the Mictacea, within which they had been previously classified, is favoured here. In addition, we highlight similarities between hirustiids and tanaidaceans that warrant further investigation. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 148 , 169–208.     

The ontogeny and homology of the Weberian apparatus in the zebrafish Danio rerio (Ostariophysi: Cypriniformes)

The ontogeny of the Weberian apparatus was examined in the zebrafish, Danio rerio , using both cleared and stained specimens and histology. Over 300 individuals from four independent zebrafish lineages, ranging in size from 3 to 28 mm TL, were examined for this study. Results provide a basic understanding of the development of the Weberian apparatus in the wild-type zebrafish. Our results, in conjunction with those already published, point to substantial variation in the development of the Weberian apparatus among otophysans and new interpretations of the homology of certain ossicles (e.g. tripus and claustrum). Hypotheses of homology among various Weberian ossicles are considered and represent an important step in understanding the evolution of sound transmission in ostariophysan fishes.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 241–254.