Notograptidae, sister to Acanthoplesiops Regan (Teleostei: Plesiopidae: Acanthoclininae), with comments on biogeography, diet and morphological convergence with Congrogadinae (Teleostei: Pseudochromidae)

The Notograptidae contains one genus, Notograptus Günther, and five nominal species from northern Australia and southern New Guinea. Morphological evidence places Notograptus among acanthoclinine plesiopids (continuous free margin of lower lip; head naked; dorsal and anal fins with many spines and few segmented rays; no extensor proprius; reduced number of caudal-fin rays) and supports a sister relationship with Acanthoplesiops (symphyseal flap on lower lip; reduced hypural 5; reduced hypurapophysis). This hypothesis resolves the relationships within Acanthoplesiops , clarifying the polarity of autogenous middle radials of dorsal- and anal-fin pterygiophores. The proposed relationships among acanthoclinines are: Acanthoclinus ( Belonepterygion ( Beliops ( Notograptus ( Acanthoplesiops hiatti ( A. indicus ( A. psilogaster ( A. echinatus ))))))). The distribution of Notograptus compliments that of its proposed sister clade in that Acanthoplesiops is unknown from northern Australia or southern New Guinea. There are repeated geographical patterns among several groups suggesting that Australia is a basal area to a broader Indo-Pacific region. Similarity between the Congrogadinae (Pseudochromidae) and Notograptus has long been noted, both having a loosely connected suspensorium and elongate body which were mistakenly considered indicators of relationship; we add reduced branchial arches, straight, tube-like gut and highly expandable anus. We examine these similarities as an indication of a shared specialized feeding habit. Notograptus is an alpheid shrimp predator, able to swallow its large prey whole. Most species of congrogadines eat whole, large crustaceans. This is probably an example of convergent adaptation to a particular selective regime.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 179–205.     

Observations on the Development of Babesia caballi (Nuttall) in the Tropical Horse Tick Dermacentor nitens Neumann

SYNOPSIS. The development of Babesia caballi (Nuttall) in Dermacentor nitens Neumann was studied in smear preparations and histologic sections of ticks infected with this protozoan parasite. A majority of the parasites in equine erythrocytes ingested by the adult ticks apparently were destroyed. Smal spherical bodies 4–6 μ in diameter were the 1st developmental stages of B. caballi observed in the gut contents of ticks infected with this parasite. These spherical bodies apparently gave rise to clavate (club-shaped) bodies 10–14 μ long by 4–6 μ wide. The latter developed into large round bodies 12–16 μ in diameter that segmented into vermicular-shaped parasites, about 8–12 μ long by 2–4 μ wide; some penetrated the gut wall, some invaded other cells of the tick.
In the cells of the Malpighian tubules, hemolymph, and ovaries, the vermicular parasites underwent a secondary cycle of multiple fission, forming vermicules similar to those occurring earlier in the gut. Vermicules that invaded the ova underwent a similar multiple fission cycle during the larval stage of the tick.
Vermicules from the multiple fission cycle that occurred during the period of larval feeding invaded the salivary glands. A multiple fission cycle of increase within these glands resulted in large numbers of small, oval and piriform parasites, 2.5–3 μ, maximum dimension. These parasites became mixed with the salivary secretions, and presumably are the forms injected into the horse by the nymphs as they feed. The small oval and piriform parasites therefore appear to be the infective stage for the horse.     

The relevance of zoological variation studies to the generic identification of fossil brachiopods

Two disturbing trends are seen in current thinking behind the establishment of new genera of fossil brachiopods; the emphasis on their applications stratigraphi-cally, and the use of progressively finer distinctions in diagnoses. The genus is a biologically based concept and thus fossil genera are only justifiable if the basis of their establishment is also biological; any stratigraphical applications are merely a by-product. The use of finer morphological distinctions in the establishment of fossil brachiopod genera in recent years runs contrary to the findings of field zoologists working on modern marine shells. Examples of the wide morphological variation in modern shells, apparently phenotypically induced, are given, the importance of this work in keeping the genus concept of the palaeontologist in perspective is stressed, and a revision of the established taxonomy of the triple-siacean Onychotreta undertaken as an illustration.     

Growth of Particle-Bearing and Particle-Free Paramecium aurelia in Axenic Culture*

SYNOPSIS. Several strains of particle-bearing and particle-free Paramecium aurelia have been cultivated in an axenic medium composed of proteose peptone, trypticase, yeast nucleic acid, MgSO⁴.7H²O, TEM-4T (diacetyl tartaric acid esters of tallow monoglycerides), stigmasterol and a mixture of vitamins. The “yeast fraction,” an indispensable component of previous media used for the cultivation of these ciliates has been replaced by a mixture of trypticase, yeast nucleic acid and TEM-4T. Particle-bearing animals of stock 299 lambda, 138 mu, and 139 pi maintain their particles when cultivated in the medium, whereas particle-bearing animals of stock 51 kappa, 225 kappa and 114 signia do not. With the exception of stock 92 (syngen 3) the medium appears to be selective in its ability to support the growth of animals of the even- but not odd-numbered syngens of P. aurelia. Maintenance of the particles was dependent only to a small degree upon environmental conditions brought about by changes in pH and temperature. Division of the particles was found to be comparable with the division of the protozoan. Methods for the growth, maintenance and mass cultivation of particle-bearing P. aurelia are given in detail.     

MAMMALIAN EXTINCTIONS IN THE LATE PLEISTOCENE OF NORTHERN EURASIA AND NORTH AMERICA

The 'mass extinctions' at the end of the Pleistocene were unique, both in the Pleistocene and earlier in the geological record, in that the species lost were nearly all large terrestrial mammals. Although a global phenomenon, late Pleistocene extinctions were most severe in North America, South America and Australia, and moderate in northern Eurasia (Europe plus Soviet Asia). In Africa, where nearly all of the late Pleistocene 'megafauna' survives to the present day, losses were slight. Ruling out epidemic disease or cosmic catastrophe, the contending hypotheses to explain late Pleistocene extinctions are: (a) failure to adapt to climatic/environmental change; and (b) extermination by human hunters ('prehistoric overkill'). This review focuses on extinctions in northern Eurasia (mainly Europe) in comparison with North America. In addition to reviewing the faunal evidence, the highly relevant environmental and archaeological backgrounds are summarized. The latest survival dates of extinct species are estimated from stratigraphic occurrences of fossil remains, radiocarbon dates, or association with archaeological industries. The Middle and Upper Pleistocene (ca. 700,000-10,000 BP) in northern Eurasia and North America was a time of constantly changing climate, ranging from phases of extensive glaciation in cold stages, to temperate periods (interglacials). In the Lateglacial (ca. 15,000-10,000 BP), during which most extinctions occurred, there was a major reorganization of vegetation, mainly involving the replacement of open vegetation by forests. These changes were more profound than earlier in the Last Cold Stage, but similar in nature to vegetational changes that took place at previous cold stage/interglacial transitions. The archaeological record shows that humans have been present in Europe since the early Middle Pleistocene. The arrival in Europe ca. 35,000 BP of 'anatomically modern humans', with their technologically more advanced upper palaeolithic industries, was a 'quantum leap' in human history. Extinctions occurred throughout the European Pleistocene, but until the late Pleistocene most losses were replaced by the evolution or immigration of new species, and most of those lost without replacement were small mammals. In marked contrast, extinctions without replacement in the late Pleistocene were almost entirely confined to the largest mammals (greater than 1000 kg) and some medium-large species (100-1000 kg).(ABSTRACT TRUNCATED AT 400 WORDS)     

Calcium and plant organelles

Abstract. The role of intracellular organelles in the regulation of cytosolic Ca²⁺ levels and whether changes in these levels affect organelle metabolism is considered. We have assessed the biochemical properties of the Ca²⁺ transporting systems in mitochondrial, chloroplast and microsomal fractions. It is proposed that although all of these organelles can transport Ca²⁺ to varying extents it would appear that in some tissues at least mitochondria do not play a significant role in the maintenance of cytosolic Ca²⁺. The most important Ca²⁺ transporting systems are probably the ATP dependent Ca²⁺ extrusion across the plasma membrane and Ca²⁺ uptake by endoplasmic reticulum, as well as light driven Ca²⁺ uptake by chloroplasts. Changes in cytoplasmic [Ca²⁺] do appear to regulate the activity of NAD kinase in chloroplasts, the mitochondrial external NADH dehydrogenase and intra-mitochondrial glutamate dehydrogenase, all of which play a key role in plant cell metabolism. Since some of these enzymes are affected by primary stimuli such as light or hormones, it is concluded that Ca²⁺ may act as a second messenger mediating some of the primary responses.     

The impact of Pleistocene glaciation across the range of a widespread European coastal species

There is a growing consensus that much of the contemporary phylogeography of northern hemisphere coastal taxa reflects the impact of Pleistocene glaciation, when glaciers covered much of the coastline at higher latitudes and sea levels dropped by as much as 150 m. The genetic signature of postglacial recolonization has been detected in many marine species, but the effects of coastal glaciation are not ubiquitous, leading to suggestions that species may intrinsically differ in their ability to respond to the environmental change associated with glacial cycles. Such variation may indeed have a biological basis, but apparent differences in population structure among taxa may also stem from our heavy reliance on individual mitochondrial loci, which are strongly influenced by stochasticity during coalescence. We investigated the contemporary population genetics of Syngnathus typhle, one of the most widespread European coastal fish species, using a multilocus data set to investigate the influence of Pleistocene glaciation and reduced sea levels on its phylogeography. A strong signal of postglacial recolonization was detected at both the northern and eastern ends of the species’ distribution, while southern populations appear to have been relatively unaffected by the last glacial cycle. Patterns of population variation and differentiation at nuclear and mitochondrial loci differ significantly, but simulations indicate that these differences can be explained by the stochastic nature of the coalescent process. These results demonstrate the strength of a multilocus approach to phylogeography and suggest that an overdependence on mitochondrial loci may provide a misleading picture of population‐level processes.     

The daily integral of photosynthesis by Planktothrix rubescens during summer stratification and autumnal mixing in Lake Zürich

It has been suggested that the populations of planktonic cyanobacteria that occupy the metalimnion of stratified lakes during the summer months may be aestivating between the main periods of growth during entrainment in the epilimnion in spring and summer. We determined the vertical distribution of the biomass and daily integral of photosynthesis of the population of Planktothrix ( Oscillatoria ) rubescens in Lake Zürich for 136 d from July to November 1995. The population showed an 80-fold increase during the stratified period but it only doubled over the subsequent period of entrainment. During the first eight days, part of the increase was attributed to recruitment of filaments floating up from greater depths but all of the subsequent production could be accounted for by photoautotrophic growth. On sunny days the biomass-specific photosynthesis of this population reached some of the highest values over the whole period despite its depth (>13 m). On very cloudy days, however, primary productivity was very low and on 4 days, when the mean depth of the population exceeded 15 m, there was no net production. Over the whole period of the study, the accumulated photosynthetic production exceeded the increase in biomass of the population by a factor of 9·5. Although much of this production occurred during the period of entrainment only a small proportion was translated into growth of the population. It is concluded that the growth that takes place in the period of stratification in the metalimnion is essential to subsequent production.