Do bonobos copulate more frequently and promiscuously than chimpanzees?

The copulatory activities of bonobos (Pan paniscus) of Wamba, Zaire, were compared with those of chimpanzees (P. troglodytes schweinfurthii) of Mahale, Tanzania. The copulation rates of adult male bonobos were equal to or lower than those of adult male chimpanzees. The copulation rates of adult female bonobos were approximately equal to those of adult female chimpanzees who were in maximal genital swelling, but it should be much higher than those of the adult female chimpanzees throughout the birth interval. The copulation rates of adolescent male bonobos were lower than those of adolescent male chimpanzees, whereas the copulation rates of adolescent female bonobos were much higher than those of adolescent female chimpanzees. It was suggested that the bonobos of Wamba did not copulate more promiscuously than did the chimpanzees of Mahale. The female bonobos may show “receptivity”, whereas female chimpanzees may show rather “proceptivity”.     

Do men yawn more than women?

The aim of this study was to test the hypothesis that sex differences in primate yawning are related to size dimorphism in canine teeth. Data were collected on yawning by a primate species (Homo sapiens) in which the two sexes differ only slightly in canine size. Unlike more dimorphic primates, human males and females did not differ in the frequency of yawning, although uncovered yawns were more frequent in men than in women.     

Do molecules matter more than morphology? Promises and pitfalls in parasites

Systematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences--morphological and molecular data--as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.     

Are deception-pollinated species more variable than those offering a reward?

In most pollination systems, animals transfer pollen among plants of a given species. Pollinator visitations do not come without cost, so plants usually offer a reward. However, the flowers of some plant species, mostly orchids, lack rewards and deceive animals into visiting their flowers. Deceptive species are thought to have high levels of variation in traits associated with advertisement and pollinator attraction, which have been attributed to genetic drift, or disruptive selection due to pollinator behavior. Rewarding species are assumed to have less variation due to stabilizing selection. We compared variability in floral morphology and fragrance composition between deceptive and rewarding species. Because both suites of traits are often linked with floral advertisement and pollinator attraction, we expected variation to be greater in species with deceptive pollination systems than in those offering rewards. We obtained floral morphology metrics for 20 deceptive species and 41 rewarding species native or naturalized in Puerto Rico, Venezuela, and Ecuador. Floral fragrances were sampled from eight deceptive species and four rewarding species. We found that the amplitude of variation in floral morphology and fragrance composition covaries significantly. Comparison of coefficients of variation for morphology indicated that, overall, deceptive species show significantly higher variation than rewarding species, and this pattern was also found among just orchids or just nonorchids. There were no statistical differences in morphological variation between orchids and nonorchids within a functional pollination group. Fragrance variation, measured by Jaccard distance, tended to be greater for deceptive species than for rewarding species. Although overlap in measures of variation occurs between the two groups, the data support the hypothesis that populations of deception-pollinated species are more variable than rewarding species in traits associated with pollinator attraction.     

Do invasive alien plants benefit more from global environmental change than native plants?

Invasive alien plant species threaten native biodiversity, disrupt ecosystem functions and can cause large economic damage. Plant invasions have been predicted to further increase under ongoing global environmental change. Numerous case studies have compared the performance of invasive and native plant species in response to global environmental change components (i.e. changes in mean levels of precipitation, temperature, atmospheric CO₂ concentration or nitrogen deposition). Individually, these studies usually involve low numbers of species and therefore the results cannot be generalized. Therefore, we performed a phylogenetically controlled meta‐analysis to assess whether there is a general pattern of differences in invasive and native plant performance under each component of global environmental change. We compiled a database of studies that reported performance measures for 74 invasive alien plant species and 117 native plant species in response to one of the above‐mentioned global environmental change components. We found that elevated temperature and CO₂ enrichment increased the performance of invasive alien plants more strongly than was the case for native plants. Invasive alien plants tended to also have a slightly stronger positive response to increased N deposition and increased precipitation than native plants, but these differences were not significant (N deposition: P = 0.051; increased precipitation: P = 0.679). Invasive alien plants tended to have a slightly stronger negative response to decreased precipitation than native plants, although this difference was also not significant (P = 0.060). So while drought could potentially reduce plant invasion, increases in the four other components of global environmental change considered, particularly global warming and atmospheric CO₂ enrichment, may further increase the spread of invasive plants in the future.     

Do most human populations descend from phylogenetic trees?

Molecular biologists and some population geneticists have recently claimed to be able to reconstruct modern human populations remote history by means of phylogenetic trees. Many objections to this method are discussed in the present paper. The most important are

1. Inter-populations migrations are likely to have been important, even in the remote past. So the “treeness” of this evolution is disputable.
2. There is no reason to believe that actual molecular phylogenies would be convergent between different molecules and would therefore represent populations history.

The various kind of genetic data, their relations to other data and the limits of their possible use in the analysis of our past are then discussed, together with the ideological background of the most common theories and of their publication. It is very likely that the history of different populations was heterogeneous. Small and isolated hunter-gatherers frequently evolving close to a phylogenetic model, while dense and increasing populations, since the Neolithic, were closer to a dynamic network model, structured by isolation by distance. In any case, our present knowledge is obviously insufficient to reconstruct our genetic past, especially on the long term, and we can only hope that the development of the HUGO Genome Diversity project is going to yield the significant information presently lacking.     

Does Speciation between Arabidopsis halleri and Arabidopsis lyrata Coincide with Major Changes in a Molecular Target of Adaptation?

Ever since Darwin proposed natural selection as the driving force for the origin of species, the role of adaptive processes in speciation has remained controversial. In particular, a largely unsolved issue is whether key divergent ecological adaptations are associated with speciation events or evolve secondarily within sister species after the split. The plant Arabidopsis halleri is one of the few species able to colonize soils highly enriched in zinc and cadmium. Recent advances in the molecular genetics of adaptation show that the physiology of this derived ecological trait involves copy number expansions of the AhHMA4 gene, for which orthologs are found in single copy in the closely related A. lyrata and the outgroup A. thaliana. To gain insight into the speciation process, we ask whether adaptive molecular changes at this candidate gene were contemporary with important stages of the speciation process. We first inferred the scenario and timescale of speciation by comparing patterns of variation across the genomic backgrounds of A. halleri and A. lyrata. Then, we estimated the timing of the first duplication of AhHMA4 in A. halleri. Our analysis suggests that the historical split between the two species closely coincides with major changes in this molecular target of adaptation in the A. halleri lineage. These results clearly indicate that these changes evolved in A. halleri well before industrial activities fostered the spread of Zn- and Cd-polluted areas, and suggest that adaptive processes related to heavy-metal homeostasis played a major role in the speciation process.     

Ribosome-inactivating proteins from plants: more than RNA N-glycosidases?

Many plants contain proteins that are capable of inactivating ribosomes and accordingly are called ribosome-inactivating proteins or RIPs. These typical plant proteins receive a lot of attention in biological and biomedical research because of their unique biological activities toward animal and human cells. In addition, evidence is accumulating that some RIPs play a role in plant defense and hence can be exploited in plant protection. To understand the mode of action of RIPs and to optimize their medical and therapeutical applications and their use as antiviral compounds in plant protection, intensive efforts have been made to unravel the enzymatic activities of RIPs and provide a structural basis for these activities. Though marked progress has been made during the last decade, the enzymatic activity of RIPs has become a controversial issue because of the concept that RIPs possess, in addition to their classical RNA N-glycosidase and polynucleotide:adenosine glycosidase activity, other unrelated enzymatic activities. Moreover, the presumed novel enzymatic activities, especially those related to diverse nuclease activities, are believed to play an important role in various biological activities of RIPs. However, both the novel enzymatic activities and their presumed involvement in the biological activities of RIPs have been questioned because there is evidence that the activities observed are due to contaminating enzymes. We offer a critical review of the pros and cons of the putative novel enzymatic activities of RIPs. Based on the available data, it is suggested that there is little conclusive evidence in support of the presumed activities and that in the past too little attention has been given to the purity of the RIP preparation. The antiviral activity and mode of action of RIPs in plants are discussed in view of their classical and presumed novel enzymatic activities.     

Do scale-free regulatory networks allow more expression than random ones?

In this paper, we compile the network of software packages with regulatory interactions (dependences and conflicts) from Debian GNU/Linux operating system and use it as an analogy for a gene regulatory network. Using a trace-back algorithm we assemble networks from the pool of packages with both scale-free (real data) and exponential (null model) topologies. We record the maximum number of packages that can be functionally installed in the system (i.e., the active network size). We show that scale-free regulatory networks allow a larger active network size than random ones. This result might have implications for the number of expressed genes at steady state. Small genomes with scale-free regulatory topologies could allow much more expression than large genomes with exponential topologies. This may have implications for the dynamics, robustness and evolution of genomes.     

Brain and testis: more alike than previously thought?

Several strands of evidence indicate the presence of marked similarities between human brain and testis. Understanding these similarities and their implications has become a topic of interest among the scientific community. Indeed, an association of intelligence with some semen quality parameters has been reported and a relation between dysfunctions of the human brain and testis has also been evident. Numerous common molecular features are evident when these tissues are compared, which is reflected in the huge number of common proteins. At the functional level, human neurons and sperm share a number of characteristics, including the importance of the exocytotic process and the presence of similar receptors and signalling pathways. The common proteins are mainly involved in exocytosis, tissue development and neuron/brain-associated biological processes. With this analysis, we conclude that human brain and testis share several biochemical characteristics which, in addition to their involvement in the speciation process, could, at least in part, be responsible for the expression of a huge number of common proteins. Nonetheless, this is an underexplored topic, and the connection between these tissues needs to be clarified, which could help to understand the dysfunctions affecting brain and testis, as well as to develop improved therapeutic strategies.     

Do island plant populations really have lower genetic variation than mainland populations? Effects of selection and distribution range on genetic diversity estimates

Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long‐standing idea that island populations have lower GD than their mainland counterparts. Plastid data showed that colonization of the Canary Islands promoted strong lineage divergence within P. laevigata, which was accompanied by selective sweeps at several nuclear microsatellite loci. Inclusion of loci affected by strong divergent selection produced a significant downward bias in the GD estimates of the mainland lineage, but such underestimates were substantial (>14%) only when more than one loci under selection were included in the computations. When loci affected by selection were removed, we did not find evidence that insular Periploca populations have less GD than their mainland counterparts. The analysis of data obtained from a comprehensive literature survey reinforced this result, as overall comparisons of GD estimates between island and mainland populations were not significant across plant taxa (N = 66), with the only exception of island endemics with narrow distributions. This study suggests that identification and removal of markers potentially affected by selection should be routinely implemented in estimates of GD, particularly if different lineages are compared. Furthermore, it provides compelling evidence that the expectation of low GD cannot be generalized to island plant populations.     

Do the Japanese feel more suspicious about cancer registration than the British?

Background: Cancer registration is indispensable, providing useful statistical measures for the appropriate evaluation of cancer control programs and medical treatment or screening. Methods: Following the British national survey on attitudes toward cancer registration, we conducted an investigation to correctly evaluate the general opinion of the Japanese population in this regard. We randomly recruited 3000 men and women aged 20–69 years from a research database. Results: Only 4% of all respondents had heard about the cancer registry system before the investigation. However, 77% of respondents thought that cancer registration was useful. Forty-three percent of respondents answered, regardless of the strictness of the data protection, that privacy had been violated if the registration occurred without an individual explanation. Compared with the British survey results, Japanese people seemed to be more suspicious about the largely unknown system of cancer registry. Nonetheless, it is noteworthy that Japanese respondents did not show active opposition to cancer registration; they tended to choose “I don’t know” instead of “no” to questions asking if they supported the registry system. Multivariate analysis showed that male sex, older age, and living in the southern region were the factors significantly associated with support for cancer registration. Conclusions: We can seek society's understanding toward cancer registration by actively utilizing information from cancer registries, by using examples of how data are actually used that have wide appeal, and by educating the public on how the data are treated under the complete privacy policy.     

Bacteriophages and pathogenicity: more than just providing a toxin?

An increasing number of pathogenicity factors carried by bacteriophages have been discovered. This review considers bacteriophage-bacterium interaction and its relation to disease processes. We discuss the search for new bacteriophage-associated pathogenicity factors, with emphasis on recent advances brought by the use of genomic sequence data and the techniques of genomic epidemiology.