Large Taxa Research Articles

Phylogenetic utility and evidence for multiple copies of elongation factor-1alpha in the spider genus Habronattus (Araneae: Salticidae).

In the continuing quest for informative genes for use in molecular systematics, the protein-coding gene Elongation factor-1alpha (EF-1alpha) has rapidly become one of the most prevalent "single-copy" nuclear genes utilized, particularly in arthropods. This paper explores the molecular evolutionary dynamics and phylogenetic utility of EF-1alpha in the salticid spider genus Habronattus. As has been reported for other arthropod lineages, our studies indicate that multiple (two) copies of EF-1alpha exist in Habronattus. These copies differ in intron structure and thus in size, making it possible to easily separate PCR amplification products. We present data for an intronless EF-1alpha copy for three Habronattus species. The presence of nonsense mutations and generally elevated rates of amino acid change suggest that this copy is evolving under relaxed functional constraints in Habronattus. A larger taxon sample (50 species plus outgroups) is presented for an EF-1alpha copy that includes both intron and exon regions. Characteristics of both regions suggest that this is a functional, orthologous copy in the species sampled. Maximum-likelihood relative-rate comparisons show that exon third codon sites are evolving more than 100 times as fast as second codon sites in these sequences and that intron sites are evolving about twice as fast as exon third sites. In combination, the EF-1alpha data provide robust, species-level phylogenetic signal that is largely congruent with morphologically well supported areas of Habronattus phylogeny. The recovery of some novel clades, and the unexpected fragmentation of others, suggests areas requiring further phylogenetic attention.

An Assessment of the Feeding Success of Young-of-the-Year Winter Flounder (Pseudopleuronectes americanus) near a Municipal Pier in the Hudson River Estuary, U. S. A.

We examined feeding success of young-of-the-year winter flounder (Pseudopleuronectes americanus Walbaum) (20–50 mm TL) around a large, municipal pier in the Hudson River estuary, USA. Replicate, 3-h feeding experiments were conducted using benthic cages (0.64 m2) deployed under, at the edge, and outside of the pier during late spring and early summer in 1998 and 1999. Significantly more winter flounder caged under piers had empty stomachs ( $$\bar x$$ =71.9%) than at the edge or in open water ( $$\bar x$$ =29.2% and 14.4%, respectively). Feeding intensity was significantly higher outside of the pier ( $$\bar x$$ =0.40%) than the edge or under the pier ( $$\bar x$$ =0.19% and 0.03%, respectively). Simultaneous with feeding experiments, benthic core samples were collected adjacent to cages. Variability was high, but abundances of prey were consistently higher under the pier ( $$\bar x$$ =200.14±113.3 SD in 1998; 335±290.2 in 1999) than at the edge ( $$\bar x$$ =126.6±50.2 in 1998; 70.8±68.5 in 1999) or in open water ( $$\bar x$$ =53.4±16.1 in 1998; 123.8±193.9 in 1999). No significant differences in prey biomass were determined, suggesting that small, numerous prey were available under the pier and fewer, larger taxa were present at the edge and outside. Data indicate that feeding is suppressed among young-of-the-year winter flounder caged under piers in spite of sufficient prey available. Based on these and other experiments we submit that areas under piers are not suitable long-term habitats for juvenile fish because they interfere with normal feeding activities.

Large dissorophoid skeletal elements from the Lower Permian Richards Spur Fissures, Oklahoma, and their paleoecological implications

ABSTRACT Skeletal remains attributable to large dissorophoid amphibians, including four femora, two humeri, and an isolated palatine bone, have recently been recovered from the Lower Permian fissure fill deposits at Richards Spur, Oklahoma. Three of the femora are assignable to Acheloma cumminsi. One humérus represents an indeterminate trematopid, perhaps A. cumminsi, whereas the remaining humerus and femur are evidently of dissorophid origin and probably assignable to Cacops. The palatine bone is of unusual morphology and evidently represents a third distinct large dissorophoid taxon. Although the Richards Spur faunal assemblage is unquestionably dominated by small animals such as Captorhinus aguti, Cardiocephalus, and Euryodus, the discovery of rare, larger skeletal elements at the site implies that some elements of the fauna approached or slightly exceeded a body length of about one meter. Although probably uncommon in the vicinity of the fissures, such larger species were clearly not excluded from the deposits by preservational biases. Like other taxa known from Richards Spur, the dissorophoids were fully terrestrial as adults, and their presence reinforces previous interpretations of the Richards Spur paleoenvironment as an arid highland region. However, some Richards Spur taxa have also been reported from lowland “deltaic” localities such as South Grandfield, Oklahoma, implying that their distribution was more cosmopolitan.

Orbit orientation and the function of the mammalian postorbital bar

AbstractThe visual predation hypothesis of primate origins was introduced by M. Cartmill in the 1970s. In outlining a series of predictions regarding changes in orbital orientation, he further posits that the formation of a bony postorbital bar is correlated with greater orbital convergence, which in turn appears to be linked to selection for increased stereoscopic visual acuity in a nocturnal milieu. A series of predictions related to this model is tested in living analogues that vary in postorbital bar formation: felid and herpestid carnivorans and the pteropodid megabats. Bivariate correlations and regressions, ANOVA and ANCOVA are used to assess the intrinsic allometric and non‐allometric factors thought to affect two aspects of orbital orientation, convergence and frontation. These angles of orbital orientation are then examined in an effort to determine how they are associated with the development of a postorbital bar. Cartmill suggested that convergent orbits develop from changes in relative orbit diameter and relative interorbital breadth. This study indicates that felids show only weak support for these predictions, while herpestids do not provide support and pteropodids show some support. Instead, in response to natural selection, convergence seems to develop to improve stereoscopic vision and depth perception in nocturnal predators. As predicted, felids show a significant positive relationship between orbital frontation and relative brain size. Analyses in herpestids, however, do not show significant relationships between frontation and relative palate length or relative brain mass. Pteropodids also do not support the model regarding intrinsic frontation factors. In both carnivoran groups, convergence and frontation are positively correlated, whereas they are not correlated in Pteropodidae. In partial contrast to Cartmill's predictions, we found that orbital convergence and/or orbital frontation are generally higher in carnivorans and bats with postorbital bars. Therefore, a greater emphasis on nocturnal stereoscopic visual predation and increased relative brain size both move the orbital aperture out of the plane of the temporal fossa and a postorbital bar thus provides adequate rigidity to the lateral orbital margin. In the more encephalized Felidae, orbital frontation is positively correlated with relative brain size; as smaller mammals have relatively larger brains, this explains why postorbital bars tend to be found in smaller felids. In herpestids and pteropodids, postorbital bars tend to occur in larger taxa which are more convergent than smaller forms.

Phylogeny of the Anopliidae (Brachiopoda: Chonetidina)

The Anopliidae is one of the most diverse families in the brachiopod suborder Chonetidina. All previous attempts to work out the phylogeny and taxonomy of this family assume that the group is monophyletic. Great phylogenetic significance has been placed on the presence or absence of a single key feature, such as radial external ornament or accessory lateral septa of the brachial valve. In order to evaluate previous classifications of the family and the characters on which they are based, we performed a cladistic analysis of 23 anopliid taxa, two outgroup taxa, Rugosochonetes and Waagenites and three problematic taxa, Trichochonetes, Airtonia and Davoustia whose inclusion within the Anopliidae has been controversial. A single most parsimonious tree was obtained, with a length of 157, CI=0.28 and RI=0.47. The results do not support previous bipartite divisions of the family. In addition, the analysis is inconsistent with the presumption of monophyly for this family. Rather, it supports restriction of the Anopliidae to a clade united by small adult length, removing several large taxa from the family and confirming the non‐anopliid status of Airtonia and Davoustia.

Selective isolation and characterisation of members of the Streptomyces violaceusniger clade associated with the roots of Paraserianthes falcataria.

Large numbers of putatively novel streptomycetes were isolated from environmental samples collected from in and around the root system of the tropical angiosperm, Paraserianthes falcataria. Representative isolates were assigned to 37 multi-membered and 107 single membered colour groups based on their ability to form pigments on oatmeal and peptone yeast extract iron agars. The largest taxon, colour group 3, encompassed 94 isolates which had morphological properties typical of members of the Streptomyces violaceusniger clade. Twelve representatives of this taxon chosen on the basis of Curie-point pyrolysis mass spectrometric data were compared with representatives of the validly described species which constitute the Streptomyces violaceusniger clade. Six out of the twelve representative strains were readily distinguished from one another and from the marker strains using a combination of genotypic and phenotypic properties. These organisms were consequently considered to merit species status as Streptomyces asiaticus sp. nov., Streptomyces cangkringensis sp. nov., Streptomyces indonesiensis sp. nov., Streptomycesjavensis sp. nov., Streptomyces rhizosphaerius sp. nov. and Streptomyces yogyakartensis sp. nov.

Biogeographical and Ecological Factors Affecting the Altitudinal Variation of Mountainous Communities of Coprophagous Beetles (Coleoptera: Scarabaeoidea): a Comparative Study

The altitudinal variation in the richness and composition of communities of coprophagous beetles in a mountainous landscape in Mexico is analyzed and the results obtained are compared with those of similar studies carried out in other parts of the world. Two nonexclusive processes are proposed as responsible for the assemblage of mountain fauna: horizontal colonization by elements originating from lineages distributed at higher latitudes and vertical colonization by lineages distributed at the same latitude but at different altitudes. The current analysis supports the hypothesis that when the horizontal colonization dominates, mountain faunas show a clear altitudinal substitution between large taxa with different evolutionary histories (e.g., Scarabaeinae and Aphodiinae) and the gradient of reduction in species richness is attenuated. This occurs in mountains of different continents and depends primarily on the degree of isolation and general orientation of the mountain ranges. Conversely, when vertical colonization dominates, mountain faunas show only slight altitudinal substitution, and the reduction in richness is greater.

Biogeography of Crustacea and Mollusca of the Subantarctic and Antarctic regions

The Joint Magellan Victor Hensen Campaign in 1994 focused on the biogeographic relationships of the Antarctic and Magellan fauna. The Peracarida and Mollusca sampled at 18 stations in the Beagle Channel by means of an epibenthic sledge were compared with the knowledge about the distribution of species data from the Falkland Islands, South Georgia, Antarctica and the Kerguelen. Peracarida were an important fraction of the macrobenthos and sampled in high numbers. About 105,000 individuals were collected with the epibenthic sledge. Until now about 40 species of Amphipoda, about 42 species of Isopoda, 24 species of Cumacea, eight species of Mysidacea, and 16 species of Tanaidacea were found. 118 mollusc taxa were identified, nine species of Aplacophora, 52 of Gastropoda, five of Scaphopoda and 52 of Bivalvia. Although the species present different distribution trends, the zoogeographic comparison for six larger taxa (four Mollusca and two Peracarida) showed that the species similarities decreased from the Magellan region towards the Falkland Islands and from South Georgia to Antarctica. The Magellanic Gastropoda showed similarities with the fauna of the Falkland Islands and South Georgia (31-37 %), whereas the Bivalvia were more similar to the Antarctic fauna (29 %). With regard to Crustacea, 10% of Antarctic Isopoda species were also found in the Magellan region; the Weddell Sea and East Antarctica, and South Georgia and the Antarctic Peninsula shared most species of both Cumacea and Isopoda, whereas the lowest similarities were shown between Bellingshausen and Weddell Sea for the Isopoda, and interestingly between the Magellan region and South Georgia for the Cumacea. The highest degree of endemism of the Isopoda and Cumacea was found in the Magellan region, where as a consequence of the opening of the Drake Passage many new species seem to have evolved in these taxa.

Trochophore concepts: ciliary bands and the evolution of larvae in spiralian Metazoa

Abstract «Trochophore» is a term used in a strict sense for larvae having an opposed-band method of feeding, involving a prototroch and metatroch. Other ciliary bands such as a telotroch and neurotroch may be present. The trochophore has been proposed to represent the ancestral larval form for a group of metazoan phyla (including all members of the Spiralia). The name trochophore is also often applied to larvae that do not conform to the above definition. A cladistic analysis of spiralian taxa (with special reference to polychaete annelids), based on a suite of adult and larval characters, is used to assess several hypotheses: (1) that the trochophore (in a strict sense) is a plesiomorphic form for the Spiralia; (2) that the strictly defined trochophore is plesiomorphic for members of the Spiralia such as the Polychaeta. The homology of each of the various separate ciliary bands of spiralian larvae, and features such as the apical tuft and protonephridia is also assessed. The results favour the conclusion that the trochophore, if defined as a feeding larval form using opposed bands, should not be regarded as an ancestral (= plesiomorphic) type for the Spiralia, or any other large taxon such as the Polychaeta or Mollusca. The evidence suggests that the various ciliary bands have differing evolutionary histories, and only the Echiura (possibly an annelid group) has members with the classical trochophore. The trochophore is re-defined as a larval form with a prototroch. This broad definition covers a wide variety of larvae, and matches the current usage more accurately than the restricted term. Features such as the neurotroch, telotroch and opposed-band feeding show convergence and reversals. The nature of the metatroch requires further investigation. The presence of a prototroch (and hence trochophore larvae) is used to identify an apomorphy-based taxon, Trochozoa, that includes the first ancestor to have evolved a prototroch and all its descendants. This minimally includes the Annelida (sensu lato), Echiura, Entoprocta, Mollusca and Sipuncula and is a less inclusive taxon than the Spiralia.

Trochophore concepts: ciliary bands and the evolution of larvae in spiralian Metazoa

«Trochophore» is a term used in a strict sense for larvae having an opposed-band method of feeding, involving a prototroch and metatroch. Other ciliary bands such as a telotroch and neurotroch may be present. The trochophore has been proposed to represent the ancestral larval form for a group of metazoan phyla (including all members of the Spiralia). The name trochophore is also often applied to larvae that do not conform to the above definition. A cladistic analysis of spiralian taxa (with special reference to polychaete annelids), based on a suite of adult and larval characters, is used to assess several hypotheses: (1) that the trochophore (in a strict sense) is a plesiomorphic form for the Spiralia; (2) that the strictly defined trochophore is plesiomorphic for members of the Spiralia such as the Polychaeta. The homology of each of the various separate ciliary bands of spiralian larvae, and features such as the apical tuft and protonephridia is also assessed. The results favour the conclusion that the trochophore, if defined as a feeding larval form using opposed bands, should not be regarded as an ancestral (= plesiomorphic) type for the Spiralia, or any other large taxon such as the Polychaeta or Mollusca. The evidence suggests that the various ciliary bands have differing evolutionary histories, and only the Echiura (possibly an annelid group) has members with the classical trochophore. The trochophore is re-defined as a larval form with a prototroch. This broad definition covers a wide variety of larvae, and matches the current usage more accurately than the restricted term. Features such as the neurotroch, telotroch and opposed-band feeding show convergence and reversals. The nature of the metatroch requires further investigation. The presence of a prototroch (and hence trochophore larvae) is used to identify an apomorphy-based taxon, Trochozoa, that includes the first ancestor to have evolved a prototroch and all its descendants. This minimally includes the Annelida (sensu lato), Echiura, Entoprocta, Mollusca and Sipuncula and is a less inclusive taxon than the Spiralia.

Research noteUltrastructure of the eyes of the larva of Neoheterocotyle rhinobatidis (Platyhelminthes, Monopisthocotylea), and phylogenetic implications

The oncomiracidium of Neoheterocotyle rhinobatidis (Monogenea, Monopisthocotylea, Monocotylidae) has two pairs of eyes, each eye with a lens and pigment cup. The anterior eyes have a single rhadomere; the posterior ones, two rhadomeres. Lenses are part of the pigment cup cells, as indicated by cytoplasmic connections between them and the pigment cups, and they are of mitochondrial origin because mitochondrial cristae are present in the periphery of the lenses. This is the first time that mitochondrial lenses have been shown to exist in a neodermatan. Such lenses may be a synapomorphy of a large taxon comprising the Neodermata and its turbellarian sister groups, or they may have evolved convergently in several not closely related groups as a result of strong selection pressure to find a suitable habitat or host.

Evolutionary immunology?

Evolutionary immunology?

What, if anything, is a cursor? Categories versus continua for determining locomotor habit in mammals and dinosaurs

AbstractTraditional categories of locomotor habit in mammals are largely based on variables that are continuous in nature, making intermediate forms difficult to evaluate quantitatively. Interpretations of these categories have varied greatly among authors, mainly owing to the inconsistent meanings ascribed to these essentially morphological variables. As a result, it is not clear whether these categories reflect any true locomotor influence, or if they can be applied in any form to non‐mammalian taxa. In order to rectify these two difficulties, locomotor categories are rejected here in favour of a multivariate continuum. By basing this continuum on morphological variables that fulfil predictions of limb design under biomechanical theory, it can be tied to limb mechanics and applied to both extant and extinct animals alike. A series of such measurements were taken from a large sample of mammal and dinosaur hindlimb bones, and subjected to statistical testing. Patterns of variation in dinosaurs are similar to those seen in mammals, ranging between extremes traditionally designated as ‘cursorial’ and ‘graviportal’. An evaluation of dinosaur locomotor evolution in light of this continuum suggests that dinosaurs originated as small cursors, but that most lineages acquired a more mid‐grade locomotor habit. Large taxa (sauropods, armoured ornithischians) were essentially graviportal, while smaller forms tended towards cursoriality; only coelurosaur theropods developed cursoriality at large body sizes. The discrepancy between large, graviportal herbivores and large, mid‐grade to cursorial carnivores in Mesozoic communities argues against pursuit predation as a major influence in dinosaur locomotor evolution.

A lesson from the past: Patterns, Processes of Vertebrate Evolution.

No wonder, to begin with, that speculations on fossil vertebrates stimulated some of the best pieces of evolutionary biology. The quality of the fossil record, especially the wealth of information we may often recover from teeth or skeletal remains, together with the subterraneous but generally unconfessed interest for a large and diverse taxon to which we ourselves belong, set the background for some of the most enjoyable and stimulating readings in our ®eld. Think, for instance, of George Gaylord Simpson's Tempo & Mode in Evolution (Simpson, 1944), a book of such an importance as to justify a jubilee (Fitch & Ayala, 1995) 50 years after it appeared in print, or of his later The Major Features of Evolution (Simpson, 1953). No wonder, then, that Robert L. Carroll's book is `dedicated to the work of George Gaylord Simpson, who brought palaeontology into the evolutionary synthesis and established the study of large-scale evolution on a strong scienti®c footing.' Carroll's book, however, is nothing of a celebrative or historical book. It is a sound, well-argued monograph on evolution, using ± as much as Simpson also did ± fossil vertebrates as the main, but not exclusive model for describing and interpreting evolutionary patterns over the scale of geological time. Carroll deals at length with several of the most controversial points in palaeobiology and evolutionary biology at large: topics obviously familiar to any reader acquainted with the evolutionary biology literature of the last couple of decades, but all too often approached through a few selected examples and in terms of philosophical controversy. This was true even of the valuable stimulating pages of the late Antoni Hoffman (1989). Here, on the contrary, the reader is offered a broad range of well-documented examples, and Carroll's conclusions often verge on the pluralistic: in the Preface, he anticipates the general conclusions of his study, which will `differ from those of Darwin, the modern evolutionary synthesis, and the theory of punctuated equilibrium in being much more pluralistic', which is repeated at the end: `[P]atterns, rates, and controlling forces are much more varied than had been conceived by either Darwin or Simpson.' (p. 390). Carroll must be congratulated on his superb ability to provide the reader with a digest of precious information on genetics and developmental biology and in carefully distinguishing between the problems where these disciplines may already help understanding the patterns from the fossil record and other still grey areas, where a similar understanding is likely to be developed, but some key information is still lacking. I dare to say that Carroll succeeded in grasping and summarizing genetics and developmental biology for palaeobiologists better than most geneticists and developmental biologists have been able to do with palaeobiological evidence. A die-hard tradition in palaeobiology is ®lling pages with statistics of ®rst occurrences, extinctions and the like. As poignantly demonstrated by Andrew Smith and the late Colin Patterson (e.g. Smith & Patterson, 1988; Smith, 1994), all those statistics are prone to very strong in uence from subjective taxonomic decisions. In Carroll's book there is still a place for that kind of numerical exercises, but not too much. Instead, the author embraces the cladistic method of counting changes of character states along the branches of a cladogramme: a beautiful example of this kind of analysis provides the backbone for his analysis of the evolution of mosasaurs. What about macroevolution? Carroll soberly rules out the existence of evolutionary mechanisms peculiar to it, but goes on commenting that `On the other hand, macroevolutionary patterns cannot be directly extrapolated from microevolution because there are additional external forces that are undetectable over short time scales and whose force, frequency, and duration are unpredictable. These include plate tectonics, with corresponding changes in climate and routes of dispersal, and mass extinction' (p. 392). To sum up, if Simpson's The Major Features of Evolution `was the latest attempt by a vertebrate palaeontologist to provide a uni®ed picture of evolutionary theory' (p. 60), now it has been replaced, in many ways, by Carroll's Patterns and Processes of Vertebrate Evolution. His last chapter includes a section entitled Agenda for the Future: `Counting taxa is never suf®cient to solve the important biological aspects of these events.' (p. 393); we need to differentiate between extinctions and pseudoextinctions, to look for processes underlying the patters, to incorporate into palaeobiology the new spectacular advances in developmental biology. But, to be sure, there is still scope for getting important lessons from the past.

Biodiversity and systematics in cephalopods: unresolved problems require an integrated approach

Some problems of cephalopod biodiversity are discussed. Many squid species are represented by 2–4 intraspecies groupings that may be wholly or partly sympatric, but differ in spawning season and size at maturity. They may be genetically distinct stock units, but their taxonomic status remains unresolved. Discovery of a biochemical or molecular key to distinguish between intra- and interspecific differences may help to solve the problem of subspecific taxa in cephalopods, as stated by G. L. Voss in 1977. Electrophoretic study of allozyme differentiation is a good method for clearing up relationships between taxa within a family, but this method cannot be used in situations when the concept of subgenus or subfamily is necessary. The problem of suprafamilial taxa needs urgent attention. However, restructuring only one family or group of families leaving others unrevised may lead to skewing the entire system. Examples are splitting the Enoploteuthidae into three families (as proposed by M. R. Clarke in 1988) and raising the rank of the Sepiidae and the Sepiolidae to ordinal, a proposal by P. Fioroni in 1981. In such cases the method of common level should be applied: subdivisions in a large taxon shall be separated by approximately similar characters. Many attempts to select natural groups of families, for example in the Oegopsida, failed primarily because they were based on analysis of a single organ or system of organs when study of other organs/systems may lead to different natural groupings. The use of molecular techniques in cephalopod phylogeny may be profitable, but initial attempts have led to results that are not easily interpretable. The evolution of Recent Cephalopoda has probably proceeded with such large variations in rates among different clades that it is impossible to construct a non-contradictory system based on any single organ or system. No single organ/system-of-organs nor single methodology currently exists that will solve every problem in taxonomy. An integrated approach, based on analysis of as many organs and different taxa as possible, is necessary to construct an accurate picture and not a mosaic of dispersed random pieces.

The evolution of body size in birds. I. Evidence for non-random diversification

The hypothesis that evolution of body size in birds was a random process coupled with an absolute lower boundary on body mass was tested using data on 6217 species of extant birds. The test was based on the fact that subclades within birds that have body masses much larger than this minimum should not have skewed log body mass distributions, while clades close to this boundary should. Bird species were classified into 23 orders suggested by Sibley and Monroe (1988). Thirteen orders that had average log body masses greater than the average for all birds had significantly skewed log body mass distributions. This is inconsistent with the hypothesis that evolution of body size in birds is random, but is constrained only at the smallest body masses. Most orders of birds cannot be considered random samples from the parental distribution of all birds. When the pattern of body mass evolution in birds is reconstructed using an estimate of the phylogenetic relationships among orders, there are many more instances where a large taxon putatively originated from a smaller one than vice versa. The non-random nature of body mass evolution in birds is consistent with models that postulate that evolution is constrained by the ability of individuals to turn resources into offspring.

Gonopod tegumental glands: a new accessory sex gland in the Brachyura

It is not yet known whether gonopod tegumental glands (GTG) previously described in one species of brachyuran crab (Chionoecetes opilio) are a general feature in this large taxon. In order to determine the prevalence and role of GTG in the Brachyura, the first gonopods of six species of boreo-temperate and tropical brachyurans belonging to four families were examined morphologically and histologically, using the PAS–Alcian-blue staining protocol: Carcinus maenas, Portunus sebae, and Ovalipes ocellatus (Portunidae), Cancer irroratus (Cancridae), Grapsus grapsus (Grapsidae), and Petrolisthes armatus (Porcellanidae). Discrete rosette-type GTG were found in all species examined, although the longitudinal extent and location differed somewhat between taxa. The GTG were invariably grouped about the ejaculatory canal, and communicated with the lumen of the ejaculatory canal via ducts which traversed pores in the cuticle; staining properties of secretions at the duct openings to the ejaculatory canal matched those of the GTG. Neither GTG, ducts, nor pores were observed in regions distal to the ejaculatory canal. These data indicate that the prime, if not exclusive, role of the GTG is in reproduction, and that GTG may therefore be considered accessory sex glands. Together with previous and current investigations such GTG have been observed in all eight brachyuran species examined from five families, and are thus probably ubiquitous within the Brachyura. The organization and nature of the gland secretions differed between taxa: alternating acid (AMPS) and neutral mucopolysaccharide (NMPS) layers in the three Portunidae, AMPS only in Cancer irroratus, and NMPS only in Grapsus grapsus and Petrolisthes armatus. When combined with data on gonopod morphology and occurrence of spermatophore-less sealant in the ejaculate of various brachyurans, two plausible functions of the AMPS GTG secretions emerge: protection of the male's genetic investment (stored spermatophores) from opportunistic microbes following copulation, and the reciprocal processes of sperm competition and paternity assurance. The NMPS secretions may function as a lubricant to reduce mechanical wear of the ejaculatory canal by the second gonopod during copulation, and to reduce the viscosity of the ejaculate from the vas deferens as it enters the narrow ejaculatory canal.

A system of large taxa of the subclass serernentea (Lonstow, 1905)

A system of large taxa of the subclass serernentea (Lonstow, 1905)

The normal Lactobacillus flora of healthy human rectal and oral mucosa.

The Lactobacillus flora of the rectal and oral mucosa was sampled from 42 healthy volunteers. Species identification was carried out by numerically comparing API 50CH fermentation patterns with type strains, using an SJ-similarity cut-off level of 79%. For the largest groups, identity was further confirmed by DNA-DNA hybridizations against the type strain of the species. Seventeen lactobacilli clusters were defined, of which most were found both on rectal and oral mucosa. The largest taxa were Lactobacillus plantarum, Lact. rhamnosus and Lact. paracasei ssp. paracasei, which were isolated from 52%, 26% and 17% of the individuals, respectively. Most isolates were tested for their capacity to adhere to the human colonic cell line HT-29 in the absence and presence of methyl-alpha-D-mannoside. Mannose-sensitive adherence to HT-29 cells was encountered in two-thirds of the Lact. plantarum isolates, but infrequently among isolates of other taxa. The results suggest that Lact. plantarum is a major colonizer of the human gastrointestinal mucosa, and that its capacity to adhere to mannose-containing receptors may be of some ecological importance.

Response of a zooplankton community to insecticide application in experimental ponds: a review and the implications of the effects of chemicals on the structure and functioning of freshwater communities

A review is presented of experimental studies in outdoor experimental ponds to investigate the effects of various insecticide exposures on natural zooplankton communities. Large zooplankton species, which generally are superior to small zooplankton species in competition, are also more sensitive to insecticides. Relatively low insecticide concentrations, which damage only large taxa ( Daphnia), may affect the population dynamics of other zooplankton indirectly through altered competitive relationships. The effects of insecticide on the zooplankton community are also influenced by factors such as temperature, chemical properties (e.g. degradation rate), population trends among the organisms, community structure (presence or absence of predators), and timing of the chemical application. These factors modify interrelationships between organisms and, therefore, control the recovery process of the zooplankton community following insecticide impacts. Results to date suggest that insecticide stress decreases the average size of the organisms, reduces energy transfer efficiency, elongates the food chain and sometimes increases species richness.