Development and characterization of eight microsatellite markers in bullet tuna (Auxis rochei)

The bullet tuna (Auxis rochei) is a worldwide species of high commercial value in Spain. Nevertheless, little information is currently available about the genetic characteristics of wild A. rochei populations. In this survey, we have developed eight new microsatellites for the bullet tuna using an enriched genome library protocol. Primers were screened on a total of 78 individuals from three wild populations (Mediterranean, Atlantic, and Pacific), revealing seven to 27 alleles per locus with expected heterozygosities ranging from 0.63 to 0.97. These markers can be potentially useful tools for use in population genetic studies.     

The Crime of Manabozo

On the explanation here given of the nature of the trickster, as the projection in myth of the magical violator of taboo, the contradictory features he presents may be elucidated one by one. A secondary feature, hitherto ignored in the Algonkin trickster myth—namely, Manabozo's brother's death—is shown to conceal the ritual murder of a near-kinsman committed in order to obtain magical power for the benefit of the group.     

MINERAL COMPOSITION OF NUDIBRANCH SPICULES

Doridacean opisthobranchs have calcium carbonate spicules intheir mantle, foot, gills and rhinophores, which are generallyfusiform or spheroid in shape. There is surprising little knowledgeof their structure, and little information is available on theirmineral composition, generally considered to be calcite. Inorder to study their compositional variability and the possiblerole of environmental temperature in their calcification, thespicules of several doridaceans, collected at different latitudes,were analysed using a diffractometer (XRD) and a SEM microscopeequippedwith an EDS spectrometer. The study yielded the followingresults, concerning the minero-chemical composition of the spicules: 1) the fusiform spicules are mainly composed of calcite (CaCO₃)and brucite (Mg(OH)₂), with a small percentage of fluorite (CaF₂).The smaller spherules are almost pure calcite; 2) the mineral composition of fusiform spicules of species collectedat different latitudes showed inter-and intra-individual differences,but the Ca/Mg ratio does not seem to vary according to the environmentaltemperature. In fact, this ratio reflects the volume percentof calcite and brucite in a crystalline aggregate, and consequently,temperature has a poor influence on spicule composition. Onthe other hand, differences between foot and mantle, not onlywithin the same species but also in the same specimen, suggestthat the animal itself can influence the ratio ofcalcite andbrucite nucleation. In this case, the different pH in mantleand foot tissue could induce a different up-take and use ofcalcium and magnesium; 3) the presence of pure calcite spherules suggests that theycould be related to variations of the ion concentration in theskin caused by pH variations due to the dermal gland activityor, more simply, could be considered as a calcium reservoirand source for the production of the slender spicules. (Received 25 August 1994; accepted 28 December 1994)     

Cortical and Nuclear Events During Cell Division and Resting Cyst Formation in Colpoda inflata

Nuclear and cortical phenomena during dividing and resting cyst formation of Colpoda inflata are described. Cell division forms a cyst and produces two or four tomites. In each tomite, the right oral field results from the proliferation of the anterior extreme of a single kinety, and the left oral field results from the proliferation of four, five, or six somatic kineties. After macronuclear division, each macronuclear mass undergoes a chromatinic extrusion process. During resting cyst formation, the oral infraciliature of the vegetative cell is resorbed. The somatic kineties dispose in a radial way and some pairs of kinetosomes disappear. As in cell division, there is an extrusion process. From these results we conclude that the resting cysts of Colpoda inflata cannot be included in any group of the previous classifications for hypotrich resting cysts. Thus, we propose a new additional group to Walker and Maugel's classification called PKR (partial-kinetosome-resorbing) cysts.     

Synergistic effects of climate change and local stressors: CO2 and nutrient-driven change in subtidal rocky habitats

Climate-driven change represents the cumulative effect of global through local-scale conditions, and understanding their manifestation at local scales can empower local management. Change in the dominance of habitats is often the product of local nutrient pollution that occurs at relatively local scales (i.e. catchment scale), a critical scale of management at which global impacts will manifest. We tested whether forecasted global-scale change [elevated carbon dioxide (CO₂) and subsequent ocean acidification] and local stressors (elevated nutrients) can combine to accelerate the expansion of filamentous turfs at the expense of calcifying algae (kelp understorey). Our results not only support this model of future change, but also highlight the synergistic effects of future CO₂ and nutrient concentrations on the abundance of turfs. These results suggest that global and local stressors need to be assessed in meaningful combinations so that the anticipated effects of climate change do not create the false impression that, however complex, climate change will produce smaller effects than reality. These findings empower local managers because they show that policies of reducing local stressors (e.g. nutrient pollution) can reduce the effects of global stressors not under their governance (e.g. ocean acidification). The connection between research and government policy provides an example whereby knowledge (and decision making) across local through global scales provides solutions to some of the most vexing challenges for attaining social goals of sustainability, biological conservation and economic development.     

Phyllanthus section Choretropsis (Euphorbiaceae) in Brazil

Section Choretropsis genus Phyllanthus (Euphorbiaceae) is formed by plants whose branches are modified into phylloclades. Despite the suitable characteristics of phylloclades within the Phyllanthus genus, the systematics of these species are poorly understood. Morphological data are presented here to allow future revision of this taxonomic group. The section is represented by nine species distributed in South America, eight of them endemic to Brazil. Our taxonomic studies distinguish the species and propose the synonymization of nine varieties of P. klotzschianus and two varieties of P. flagelliformis based on vegetative and reproductive characters. The diversity of branching and the morphology of phylloclades are discussed.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 131–164.     

The evolution of nocturnal behaviour in sweat bees,Megalopta genalis and M. ecuadoria (Hymenoptera: Halictidae): an escape from competitors and enemies?

Evolutionary transitions to dim-light foraging (predawn matinal, crepuscular, nocturnal) have occurred repeatedly in bees, and may be associated with an escape from enemies or competitors. To date, however, little information has been available to test these hypotheses. Here we provide the first detailed information on the nesting behaviour of two species of Neotropical, nocturnal sweat bees, Megalopta genalis and M. ecuadoria (Hymenoptera: Halictidae). Females are facultatively social or solitary, and construct nests in dead wood. Nocturnal foraging behaviour is bimodal. Bees began foraging after sunset (∼18:30 h) and ceased foraging approximately 1 h later even though nocturnal flowers with pollen were still abundant; a second foraging bout occurred in the predawn morning, which began at ∼04:45 h and ended around sunrise (∼06:15 h) when diurnal-blooming flowers were abundant. Bees are capable of controlled flight in full light. They utilized pollen from both canopy and understory plant species, which have diurnal or nocturnal pollen anthesis. Megalopta nests are attacked by generalist predators such as ants, as well as the endoparasitic fly Melaloncha sp. nov. (Phoridae), the beetle Macrosaigon gracilis (Rhipophoridae), the parasitic wasp Lophostigma cincta (Mutillidae), and the brood parasite Megalopta byroni (Halictidae). Overall nest survivorship rates were comparable to those for diurnal relatives, but rates of cell parasitism for Megalopta (< < 5%) were substantially lower than they are for day-flying relatives, offering some support for the hypothesis that the evolution of nocturnal behaviour enables escape from natural enemies.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 377–387.     

The mushroom habitat as an ecological arena for global exchange of Wolbachia

Wolbachia infect a variety of arthropod and nematode hosts, but in arthropods, host phylogenetic relationships are usually poor predictors of strain similarity. This suggests that new infections are often established by horizontal transmission. To gain insight into the factors affecting the probability of horizontal transmission among host species, we ask how host phylogeny, geographical distribution and ecology affect patterns of Wolbachia strain similarity. We used multilocus sequence typing (MLST) to characterize Wolbachia strain similarity among dipteran hosts associated with fleshy mushrooms. Wolbachia Supergroup A was more common than Supergroup B in Diptera, and also more common in mycophagous than non‐mycophagous Diptera. Within Supergroup A, host family within Diptera had no effect on strain similarity, and there was no tendency for Wolbachia strains from sympatric host species to be more similar to one another than to strains from hosts in different biogeographical realms. Supergroup A strains differed between mycophagous and non‐mycophagous Diptera more than expected by chance, suggesting that ecological associations can facilitate horizontal transmission of Wolbachia within mycophagous fly communities. For Supergroup B, there were no significant associations between strain similarity and host phylogeny, biogeography, or ecology. We identified only two cases in which closely related hosts carried closely related Wolbachia strains, evidence that Wolbachia‐host co‐speciation or early introgression can occur but may not be a major contributor to overall strain diversity. Our results suggest that horizontal transmission of Wolbachia can be influenced by host ecology, thus leading to partial restriction of Wolbachia strains or strain groups to particular guilds of insects.     

The stem xylem of Patagonian shrubs operates far from the point of catastrophic dysfunction and is additionally protected from drought‐induced embolism by leaves and roots

Hydraulic architecture was studied in shrub species differing in rooting depth in a cold desert in Southern Argentina. All species exhibited strong hydraulic segmentation between leaves, stems and roots with leaves being the most vulnerable part of the hydraulic pathway. Two types of safety margins describing the degree of conservation of the hydraulic integrity were used: the difference between minimum stem or leaf water potential (Ψ) and the Ψ at which stem or leaf hydraulic function was reduced by 50% (Ψ – Ψ₅₀), and the difference between leaf and stem Ψ₅₀. Leaf Ψ₅₀ – stem Ψ₅₀ increased with decreasing rooting depth. Large diurnal decreases in root‐specific hydraulic conductivity suggested high root vulnerability to embolism across all species. Although stem Ψ₅₀ became more negative with decreasing species‐specific Ψ_soil and minimum stem Ψ, leaf Ψ₅₀ was independent of Ψ and minimum leaf Ψ. Species with embolism‐resistant stems also had higher maximum stem hydraulic conductivity. Safety margins for stems were >2.1 MPa, whereas those for leaves were negative or only slightly positive. Leaves acted as safety valves to protect the integrity of the upstream hydraulic pathway, whereas embolism in lateral roots may help to decouple portions of the plant from the impact of drier soil layers.