Functional morphology, ecology, and evolution of the Scaphitaceae Gill, 1871 (cephalopoda)

Scaphitids are heteromorph ammonites exhibiting morphologicaltrends counter to of those of the other main heteromorph ammonitegroups. These trends include the shortening of the body chamber,lateral compression of the whorl, closure of the coil, and moreregular, spiral coiling. Scaphitid-like morphologies may haveappeared in other heteromorphs, but the Scaphitaceae are monophyletic.The most primitive scaphitids are known from the Albian, butan important radiation occurred in the Western Interior Seawayof North America from the Santonian to Maastrichtian, some ofwhich spread to the Old World. The scaphitid morphology is consistentwith improved swimming abilities, but scaphitids remained associatedwith the seafloor and are best considered to have been nektobenthossimilar to modern nautiluses.     

Package models and the information crisis of prebiotic evolution

The coexistence between different types of templates has been the choice solution to the information crisis of prebiotic evolution, triggered by the finding that a single RNA-like template cannot carry enough information to code for any useful replicase. In principle, confining d distinct templates of length L in a package or protocell, whose survival depends on the coexistence of the templates it holds in, could resolve this crisis provided that d is made sufficiently large. Here we review the prototypical package model of Niesert et al. [1981. Origin of life between Scylla and Charybdis. J. Mol. Evol. 17, 348-353] which guarantees the greatest possible region of viability of the protocell population, and show that this model, and hence the entire package approach, does not resolve the information crisis. In particular, we show that the total information stored in a viable protocell (Ld) tends to a constant value that depends only on the spontaneous error rate per nucleotide of the template replication mechanism. As a result, an increase of d must be followed by a decrease of L, so that the net information gain is null.     

Ammonoid evolution in marine ecosystems prior to the Permian-Triassic crisis

Evolutionary trends in ammonoid communities in the Middle and Late Permian are analyzed in connection with the changes in their taxonomic, morphological, geographical, and ecological structure. It is shown that the processes that led to the almost complete disappearance of the subclass began long before the global Permian-Triassic crisis.     

Retrograde evolution of Albaillella during the Permian-Triassic crisis

In the present paper, we discuss the evolution of an upper Permian anagenetic lineage of polycystine radiolarians belonging to the genus Albaillella. This genus is characterized by increasing curvature of the shell during the upper Permian and the trend is reversed (proteromorphic retrogradation) in the Lower Triassic with the sudden appearance of forms that are homeomorphic to the earliest Permian representative of the genus. These primitive-looking forms are derived from their immediate ancestors by retrograde evolution, a phenomenon which has been described as proteromorphosis.     

Respirometry and swimming dynamics of the giant australian cuttlefish, sepia apama (mollusca, cephalopoda)

Swimming dynamics of the giant Australian cuttlefish, Sepia apama, were investigated using swimtunnel respirometry. Relationships between jet pressure, fin frequency, swimming speed and oxygen consumption were defined. Laboratory calibration of swimming parameters is necessary to allow estimates of swimming costs in the field.

Jet pressure was the best predictor of oxygen consumption with an averaged equation of MO₂ = 722 (jet pressure) + 107 r² = 0.51. Individually, fin frequency and jet pressure correlated highly to swimming speed, but due to the complicated usage of finning and jetting, the correlation between swimming speed and oxygen consumption was weaker. Cuttlefish were not optimal swimtunnel subjects and could not swim at high speeds for extended periods. At 15°C and a swimming speed of 0.06 m s^-1, the gross cost of transport was calculated to be 10.1 kg^-1 m ^-1, with a net cost of 4.1 kg^-1 m^-1.     

Biotech in the financial crisis

Cover illustration: Biotech in the financial crisis. This special issue of Biotechnology Journal covers how the current financial turmoil creates problems but also chances for biotech. Forum articles and biotech highlights ask whether biotech can rescue economy and environment (green growth). Image © PhotoDisc, Inc.     

Localization of catecholamine-containing nerve fibres in the branchial heart and cardiac ganglion of the common cuttlefish Sepia officinalis L. (cephalopoda)

The innervation of the branchial heart of Sepia officinalis was examined using TEM and glyoxylic acid induced fluorescence. In the cardiac ganglion and in cardiac nerves bluish-green fluorophores were seen associated with perikarya and varicose nerve fibres. Microspectrofluorometric analysis provided clear evidence that monoaminergic neurons in the branchial heart contain only catecholamines. Considering pharmacological data, it is more than likely that 5-hydroxytryptamine (serotonin) is not present in this system.     

Phylogeny and historical biogeography of the loliginid squids (Mollusca: cephalopoda) based on mitochondrial DNA sequence data

The cephalopod taxon Loliginidae (Cephalopoda: Myopsida) is a species-rich group of tropical and temperate shallow-water squids, many of which are commercial fisheries objects and neurophysiological research organisms. The worldwide distribution of these squids could make Loliginidae a useful case study in shallow-water marine biogeography, but the phylogeny of the group is unknown. To clarify loliginid phylogeny, regions of two mitochondrial genes (the 16S rRNA and the cytochrome c oxidase subunit I genes) were sequenced for members of 19 loliginid species and several outgroups. Maximum-parsimony and maximum-likelihood analyses were performed on a combined data set, as well as on each data set individually. Analyses of the combined data support loliginid monophyly and reveal four clades-one consisting primarily of species in American waters from two genera, one composed of 3 east Atlantic species, one consisting of the bioluminescent loliginids (Uroteuthis sensu Vecchione et al., 1998) plus Loliolus japonica, and one represented by a Loligo (Alloteuthis) subulata-Lolliguncula mercatoris pair. The likelihood of the unconstrained maximum-likelihood tree is not significantly better than the likelihoods of the best trees constrained to Sepioteuthis monophyly or Uroteuthis monophyly, but there is significant support for Lolliguncula polyphyly. Tests of alternative hypotheses of loliginid cladogenesis suggest that cladogenesis within Loliginidae is correlated with the widening of the Atlantic and the closure of the Tethys Sea, although dispersal from the Indo-West Pacific is a reasonable explanation for the origin of the clade of American loliginines.     

Times of Plenty, Times of Less: Last-Millennium Societal Disruption in the Pacific Basin

During the last millennium in the Pacific Basin (islands and continental rim) there was a marked contrast between ‘times of plenty’ and ‘times of less’ for its human societies. This contrast is attributable to climate and sea-level variations, notably the Medieval Warm Period (a.d. 700–1250) and the Little Ice Age (a.d. 1350–1800) separated by a time of rapid cooling and sea-level fall called the ‘a.d. 1300 Event.’ Outlines of the times of plenty during the Medieval Warm Period and the times of less during the Little Ice Age are given, supported by a number of examples. These confirm a general picture of societal collapse as a result of the a.d. 1300 Event. Well-dated human responses to the a.d. 1300 Event (establishment of fortified settlements, end of ocean voyaging) allow links to potential nonhuman causes to be strengthened. Although more data referring to both (natural) changes and their human effects are needed, a conclusion involving environmental determinism is inescapable.