Was Homo erectus responsible for the hand-axe culture?

This paper reviews the evidence from Africa, Asia and Europe of the cultural associations of Middle Pleistocene hominids, as well as the hominid skeletal associations of hand-axe remains.The author points out that it is possible to make a good argument—from the evidence of Steinheim, Kanjera and Swanscombe—that the hand-axes at these sites were made by Homo sapiens. On the other hand, on the basis of Fontéchevade and Vértesszöllös, it could be claimed that Middle Pleistocene Homo sapiens was responsible for primitive flake and chopper cultures. The evidence from Java is negative while that from China is directly opposed to the view that Homo erectus made hand-axes. Only from Ternifine in Algeria and Olduvai in Tanzania is there suggestive evidence that Homo erectus in those areas might have been responsible for the hand-axe culture. Thus, it is not possible at present to make any categorical statements as to the makers of either the great hand-axe culture or the flake and chopper culture, during Middle Pleistocene times.     

Is the originality of a species measurable?

In this paper, we introduce the concept of 'originality of a species within a set' in order to indicate the average rarity of all the features belonging to this species. Using a phylogenetic tree of 70 species of New World terrestrial Carnivora, we suggest measuring the originality by a probability distribution. This maximizes the expected number of features shared by two species randomly drawn from the set. By using this new index, we take account of branch lengths whereas current indices of originality focus on tree topology. As a supplement to Nee and May's optimizing algorithm, we find that originality must be one of the criteria used in conservation planning.     

Is the Iberian lacewing Chrysopa regalis a semivoltine species?

ABSTRACT.

• 1 Adults of the lacewing Chrysopa regalis Navás were caught in north Spain, Huesca province, Aragon.
• 2 Their progeny reared in the laboratory under short- and long-day light conditions at 20°C, entered a long diapause as prepupae within the cocoon.
• 3 Transferred outdoors after spinning up, only a few (12%) became active again in the following spring, whereas the rest remained in diapause for one more year and waited for the end of the second spring to resume their morphogenetic development. Thus most of the studied strain exhibited a 2–year life cycle. This semivoltine strategy is new to chrysopid biology.
• 4 The predaceous larval phase did not exceed 3% of the total individual lifespan, though the duration of the free-living larval instars averaged 19.9±1.1 (SD) days.
• 5 During the extended diapause, weight loss was very small, no more than 6.6% of the initial weight, 16.9±2.7 (SD) mg, at the end of diapause, and 8.8% at the time of pupal ecdysis.

     

Developmental integration in a complex morphological structure: how distinct are the modules in the mouse mandible?

The mouse mandible has long served as a model system for studying the development and evolution of complex morphological structures. We used the methods of geometric morphometrics to reassess the hypothesis that the mandible consists of two separate modules: an anterior part bearing the teeth and a posterior part with muscle attachment surfaces and articulating with the skull. The analyses particularly focused on covariation of fluctuating asymmetry, because such covariation is due exclusively to direct interactions between the developmental processes that produce the traits of interest, whereas variation of traits among individuals also reflects other factors. The patterns of fluctuating asymmetry and individual variation were only partly consistent, indicating that developmental processes contribute differentially to variation at different levels. The results were in agreement with the hypothesis that the anterior and posterior parts of the mandible are separate develop-mental modules. Comparison of all alternative partitions of the landmarks into two contiguous subsets confirmed the hypothesis for the location of the boundary between modules but also underscored that the separation between them is not complete. Modularity is therefore manifest as the relative independence of parts within the framework of overall integration of the mandible as a whole-it is a matter of degrees, not all or nothing.     

Is Giardia a significant pathogen in production animals?

Although Giardia duodenalis is recognised worldwide as the most important parasitic cause of gastro-intestinal disorder in human patients, the relevance of infection in production animals is prone to debate. Since the 1980s, clinical disease has been associated with giardiasis in production animals, both in natural conditions and in experimental studies. However, most Giardia research is focussed on the relevance of production animals as a reservoir for zoonotic transmission. In this study, the current knowledge on clinical relevance of giardiasis in production animals is reviewed, along with the diagnosis, treatment and control of infection. Furthermore, future research objectives are discussed.     

Is the Wild Coast in eastern South Africa a distinct marine bioregion?

The South African coastline can be divided into at least four temperature-defined marine bioregions, including the tropical north-east coast, the subtropical east coast, the warm-temperate south coast, and the cool-temperate west coast. There are also two biogeographical transition zones, the south-west coast and the south-east coast (or Wild Coast). The former is sometimes considered a distinct marine bioregion, but no such status has yet been suggested for the Wild Coast. Previous data on the distribution of a recently described but very common coastal crab, Hymenosoma longicrure, indicated that this species could be a Wild Coast endemic. If confirmed, this would be a first indication that this region harbours unique fauna, and that additional research is required to determine whether the Wild Coast constitutes a distinct bioregion that needs to be managed separately from other coastal regions. In the present study, we generated novel genetic data for H. longicrure and compared the species’ range with that of its southern African congeners. We found that H. longicrure occurs north of the Wild Coast, where its range overlaps with that of H. projectum. This finding rejects the idea that the Wild Coast harbours endemic fauna and suggests that the ranges of the two species may be linked to the subtropical and tropical bioregions, respectively, with some southward dispersal facilitated by the southward-flowing Agulhas Current. We conclude that there is as yet no compelling evidence that the Wild Coast is a distinct marine bioregion, and concur with previous biogeographical studies which have suggested that the Wild Coast is an area in which species from the subtropical and warm-temperate bioregions have overlapping ranges. Nonetheless, that fact that no biological information is available for the majority of the region’s estuaries highlights the necessity of comprehensively documenting the biodiversity of this understudied region to fully resolve this issue.     

Is Karenia brevis really a low-light-adapted species?

Despite nearly annual blooms of the neurotoxic dinoflagellate Karenia brevis (Davis) G. Hansen and Moestrup in the Gulf of Mexico, defining the suite of biological traits that explain its proliferation has remained challenging. Studies have described K. brevis as a low-light-adapted species, incapable of sustaining growth under high light, which is at odds with observed surface aggregations sometimes within centimeters of the sea surface and also with short-term experiments showing photosynthetic machinery accommodating high irradiances. Here, growth and photophysiology of three K. brevis isolates were evaluated under a range of environmentally relevant irradiances (10–1500 μmol photons m⁻² s⁻¹) in the laboratory. No differences in growth–irradiance curves were observed among isolates; all sustained maximum growth rates at the highest irradiances examined, even in exposures as long as three weeks. The growth efficiency α of K. brevis under light-limiting conditions appeared mediocre among dinoflagellates, and poorer than that of other phytoplankton (e.g., diatoms, cyanobacteria), implying that K. brevis is not a low-light specialist. This finding substantially alters earlier parameterizations of K. brevis growth–irradiance curves. Therefore, a model was developed to contextualize how these new growth–irradiance curves might affect bottom growth rates. This model was subsequently applied to a case study comparing seasonal light forcing offshore of Pinellas County, FL, USA, with a single empirical value for light attenuation, and seasonal bottom water temperatures. Predictions suggested that light may limit bottom growth as close as 1 km from shore in winter, but would only begin limiting growth 20 km from shore in summer. Population maintenance (no net growth) was possible as far offshore as 90 km in summer and 68 km in winter. These ranges intercept areas thought to be important for bloom initiation.     

Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

We studied the immune response to Bacillus thuringiensis kurstaki (Btk) in susceptible (Bt-RS) and resistant (Bt-R) Trichoplusia ni after exposure to low doses of Btk and injection with Escherichia coli. We measured the levels of resistance, the expression profiles of hemolymph proteins, the phenoloxidase (PO) activity, and the differential number of circulating hemocytes in resistant and susceptible individuals. Individuals from the Bt-RS line became more resistant following a previous exposure to sub lethal concentrations of Btk, but the resistance to Btk of the Bt-R line did not change significantly. Similarly the Bt-R strain showed no significant changes in any of the potential immune responses, hemolymph protein levels or PO activity. The number of circulating hemocytes was significantly lower in the Bt-R strain than in the Bt-RS strain. Exposure to Btk decreased the hemocyte counts and reduced PO activity of Bt-RS larvae. Hemolymph protein concentrations also declined significantly in the susceptible larvae continually exposed to Btk. Seven peptides with antibacterial activity were identified in the hemolymph of Bt-RS larvae after exposure to Btk and five were found in the Bt-R larvae. When exposed to a low level Bt challenge the susceptible strain increases in tolerance and there are concomitant reductions in hemolymph protein concentrations, PO activity and the number of circulating hemocytes.     

Is telomere erosion a mechanism of species extinction?

According to the fossil record, 99.9% of all species that have ever lived on Earth have disappeared. However, only about 4% died out during the five mass extinction events, whereas it seems that the majority of species vanished without any signs of significant earthbound or extraterrestrial physical threats. Clearly, biological extinction mechanisms are by far the most important, but they are subject to serious limitations concerning the worldwide disappearance of species. In view of that, species-inherent mechanisms, which could lead to the worldwide destabilization of a population, might be worth reconsideration. Telomeres, the protective caps of chromosome ends, and the enzyme telomerase have been well preserved in plants and animals during evolution. In the absence of telomerase activity, telomeric DNA has been shown to shorten every time a cell divides. The concept of a mitotic clock based on the gradual erosion of telomeres is now generally accepted and has been confirmed in numerous plants and animals. Chromosomal rearrangements are the hallmarks of two completely different biological phenomena, cancer and speciation. In premalignant cells, gradual telomere erosion beyond a critical threshold is a well-known inducer of chromosomal instability. The species clock hypothesis, as presented here, is based on the idea of a tiny loss of mean telomere length per generation. This mechanism would not rapidly endanger the survival of a particular species. Yet, after many thousands of generations, critically short telomeres could lead to the weakening and even the extinction of old species and would simultaneously create the unstable chromosomal environment that might result in the origination of new species.     

Is the Pope a Catholic?

The whole-part relationship is generally considered transitive, but there are some apparent exceptions. Componential sortals create some apparent problems. Homo sapiens, the Pope, and his heart are all individuals. A human being, such as the Pope, is an organism-level component of Homo sapiens. The Pope’s heart is an organ-level component of both Homo sapiens and the Pope. Although the Pope is a part, and not an instance, of the Roman Catholic Church, it seems odd to say that his heart is a part of that church. This is largely because the Pope’s heart does not have a place in the ecclesiastical government. However, it does contribute to the functioning of the organization. One popular alternative to the view that Homo sapiens is an individual is the notion that it is a natural kind. This has been done by redefining ‘natural kind’ in such a manner that not just the Roman Catholic Church, but the Pope and every other human being is a natural kind as well.     

Is <Emphasis Type="Italic">Testudo werneri</Emphasis> a distinct species?

Sequence variation of a 1066 bp long mtDNA fragment (cytochrome b gene, adjacent part of tRNA-Thr gene) of four known-locality samples of Testudo kleinmanni (Tripolitania, Libya) and of four samples of T. werneri (Negev, Israel) is compared with additional five sequences of pet trade tortoises allegedly representing T. kleinmanni. Four haplotypes, differing in one to four mutation steps occur. The most common haplotype was shared by all known-locality samples of T. kleinmanni and three T. werneri. Sequence variation within each nominal species and in the pooled sample of T. kleinmanni, T. werneri and pet trade tortoises is the lowest known for any Testudo species. We conclude there is no support for the validity of T. werneri Perälä, 2001.     

Is the Testis a Chemo-Privileged Site? Is There a Blood-Testis Barrier?

The incidence of testicular cancer, primarily seminoma, has been increasing in many countries, including the United States. The testis is often the site of residual cancer after adequate treatment with systemic chemotherapy. The blood-testis barrier is commonly cited as the explanation for residual tumor within the gonad after chemotherapy and as the indication for delayed orchiectomy. Conversely, complete eradication of viable tumor from the primary site is common and argues against the testis as a "tumor sanctuary." Residual tumor is also demonstrated within metastatic foci, and the disparity between the histopathologic response of the primary tumor and metastatic sites may be best explained by tumor heterogeneity and multiple tumor clones. Regardless of the scientific and academic arguments, delayed radical orchiectomy remains an important part of treatment for patients undergoing primary chemotherapy.     

Older species: a rejuvenation on coral reefs?

Aim To discuss the theory that the present high species diversity and apomorphic character of the coral reef ecosystem is because of the historic accumulation of basal species from marginal habitats. Location The Indo‐West Pacific Ocean. Methods The examination of biogeographical patterns from the standpoint of paleontology, phylogeny, genetics, and empirical data. Results Fossil patterns from several clades indicate a gradient of increasing average generic age that extends outward from the high diversity reefs. Successful species that give rise to new species, genera, and families apparently originate from high diversity locations. The tropics have been a major source of evolutionary novelty, not simply a refuge that has accumulated diversity. Many plesiomorphic clades, that once dominated the shallow tropics, are now limited to the deep sea and other safe places. Recent research on several tropical fish families indicates that more apomorphic species inhabit the high diversity reefs. Genetic studies suggest that a decrease in genetic variation extends from the diversity centre toward the outer reaches of the Indo‐West Pacific. Empirical data show that it is extremely difficult for species from low diversity areas to invade places of higher diversity. Main conclusions There is no convincing evidence to indicate that basal species from marginal habitats have been able to accumulate on the coral reefs. Once such species have been displaced from a high diversity environment, there is apparently no return. The evolutionary innovations that contribute to the origination of new phyletic lines take place under conditions of high diversity and maximum competition.     

Is the Effect of Aerobic Exercise on Cognition a Placebo Effect?

A number of studies and meta-analyses conclude that aerobic fitness (walking) interventions improve cognition. Such interventions typically compare improvements from these interventions to an active control group in which participants engage in non-aerobic activities (typically stretching and toning) for an equivalent amount of time. However, in the absence of a double-blind design, the presence of an active control group does not necessarily control for placebo effects; participants might expect different amounts of improvement for the treatment and control interventions [1]. We conducted a large survey to explore whether people expect greater cognitive benefits from an aerobic exercise intervention compared to a control intervention. If participants expect greater improvement following aerobic exercise, then the benefits of such interventions might be due in part to a placebo effect. In general, expectations did not differ between aerobic and non-aerobic interventions. If anything, some of the results suggest the opposite (e.g., respondents expected the control, non-aerobic intervention to yield bigger memory gains). These results provide the first evidence that cognitive improvements following aerobic fitness training are not due to differential expectations.     

Sympatric morphotypes of the restricted-range Tashan Cave Garra: distinct species or a case of phenotypic plasticity?

Environmental Biology of Fishes - Among Tashan cave barb Garra tashanensis inhabiting a small cave in southwest Iran, two mental disc (sucking mouth disc) forms were observed. To assess their...