On the iterated prisoner's dilemma in a finite population

Two standard assumptions in analytical work on the iterated prisoner's dilemma are that the population is infinite, and that opponents—though randomly selected—are fixed for the duration of the game. This paper explores the consequences of relaxing both assumptions. It is shown in particular that if opponents are drawn at random throughout the game, then stable cooperation via reciprocity requires both that the probability of a further interaction be sufficiently high—higher than when opponents are fixed—and that the population not exceed a certain critical size, which depends on the probability of further interaction.     

The role of Asia in the global trade in CITES II-listed poison arrow frogs: hopping from Kazakhstan to Lebanon to Thailand and beyond

We report on the international trade in South American poison arrow frogs (Dendrobatidae) in the period 2004–2008, and focus on the role of Asian countries. All species of dendrobatid frogs are included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), regulating all commercial trade in these species. Based on data compiled in the WCMC CITES database, we establish that >63,000 dendrobatid frogs (of 32 species) were traded internationally. For 21 species the majority of individuals were reported as captive-bred. A quarter to a fifth of the commercial trade in dendrobatid frogs in terms of volume is destined for Asian markets (mainly Japan, Thailand and Taiwan, Province of China). Kazakhstan, the main supplier for the Thai market, is reported as a source country for 16 species, all captive-bred. We found large discrepancies between the reported export of dendrobatid frogs from Kazakhstan—none—and imports reported by Thailand as coming from Kazakhstan (>2,500 individuals). A significant part of the trade flow goes via Lebanon, a non-CITES Party. We urge the CITES Management Authorities of the countries involved to investigate the trade in dendrobatid frogs to ensure it does not violate the rules and intentions of CITES.     

A decade of change in the saproxylic beetle fauna of eucalypt logs in the Warra long-term log-decay experiment,Tasmania. 1. Description of the fauna and seasonality patterns

The first decade of sequential and cyclical sampling of saproxylic beetles by means of eclector traps on 12 freshly-felled Eucalyptus obliqua logs at Warra, Tasmania has allowed documentation of a taxonomically and ecologically diverse fauna present in such logs in their early decompositional state. About half of all species are apparently undescribed—a much higher proportion than in most temperate regions. The distribution of individuals among species is typically skewed, with most species being rare and few being common. Neither obligately nor facultatively saproxylic beetles dominate the fauna, but predators predominate over other larval feeding guilds, and—in accordance with ecological theory for early successional habitats—winged species predominate over functionally flightless species. There is some suggestion that trophic structure changed over the period of the study, with the proportion of functionally flightless species increasing. The fauna shows strong seasonality. While the summer months represent the peak of occurrence for most species (in keeping with the cool-temperate climate), every month has its own particular complement of species, such that a strong seasonal cycle in assemblage composition is apparent throughout the year. The timings of emergence peaks vary among the years represented in this study by up to 2 months, with the year of latest emergence corresponding to that with the lowest mean annual maximum temperature; no signature of climate change is evident in the data-set.     

Mapping Bushmeat Hunting Pressure in Central Africa

Hunting and trade of wild animals for their meat (bushmeat), especially mammals, is commonplace in tropical forests worldwide. In West and Central Africa, bushmeat extraction has increased substantially during recent decades. Currently, such levels of hunting pose a major threat to native wildlife. In this paper, we compiled published data on hunting offtake of mammals, from a number of studies conducted between 1990 and 2007 in Cameroon, Central African Republic, Democratic Republic of Congo, Equatorial Guinea, Gabon, and Republic of Congo. From these data sources, we estimated annual extraction rates of all hunted species and analyzed the relationship between environmental and anthropogenic variables surrounding each hunting rate and levels of bushmeat extraction. We defined hunting pressure as a function of bushmeat offtake and number of hunted species and confirm that hunting pressure is significantly correlated with road density, distance to protected areas and population density. These correlations are then used to map hunting pressure across the Congo Basin. We show that predicted risk areas show a patchy distribution throughout the study region and that many protected areas are located in high‐risk areas. We suggest that such a map can be used to identify areas of greatest impact of hunting to guide large‐scale conservation planning initiatives for central Africa.     

The freshwater aquarium trade as a vector for incidental invertebrate fauna

The aquarium trade has a long history of transporting and introducing fish, plants and snails into regions where they are not native. However, other than snails, research on species carried “incidentally” rather than deliberately by this industry is lacking. I sampled invertebrates in the plankton, and from water among bottom stones, of 55 aquaria from 43 New Zealand households. I recorded 55 incidental invertebrate taxa, including copepods, ostracods, cladocerans, molluscs, mites, flatworms and nematodes. Six were known established non-indigenous species, and eight others were not previously recorded from New Zealand. Of the latter, two harpacticoid copepod species, Nitokra pietschmanni and Elaphoidella sewelli, are not native to or known from New Zealand, demonstrating the aquarium trade continues to pose an invasion risk for incidental fauna. The remaining six species were littoral/benthic rotifers with subtropical/tropical affinities; these may or may not be native, as research on this group is limited. A variety of behaviours associated with the set-up and keeping of home aquaria were recorded (e.g., fish and plants in any home were sourced from stores, wild caught, or both, and cleaning methods varied), which made prediction of “high risk” behaviours difficult. However, non-indigenous species had a greater probability of being recorded in aquaria containing aquatic plants and in those that were heated. Methods for disposal of aquarium wastes ranged from depositing washings on the lawn or garden (a low risk for invasion) to disposing of water into outdoor ponds or storm-water drains (a higher risk). It is recommended that aquarium owners be encouraged to pour aquarium wastes onto gardens or lawns—already a common method of disposal—as invasion risk will be minimised using this method.     

Cat Dilemma: Too Protected To Escape Trophy Hunting?

Trophy hunting is one of the most controversial issues in the field of biodiversity conservation. In particular, proponents and opponents debate fiercely over whether it poses a threat to hunted populations. Here, we show that trophy hunting constitutes a greater menace to threatened species than previously realized. Because humans value rarity, targeted species that are threatened are likely to be disproportionately hunted, thereby becoming even more vulnerable, which could eventually push them to extinction. With the ten felid species currently hunted for their trophies, we present evidence that (1) the number of killed individuals increases with time, in several cases exponentially, despite population declines, (2) the price of trophies is strongly dependent on species protection status, (3) changes of protection status coincide with counter-intuitive changes of hunting pressures: protection intensification with augmented hunting effort, and protection relaxation with lower effort. This suggests an over-exploitation of trophy-hunted felids and the necessity of a better quota system coupled with reconsidered protection methods.     

Loopholes in the regulation of invasive species: genetic identifications identify mislabeling of prohibited aquarium plants

Numerous invasive aquatic species introductions can be traced to the aquarium trade. Many potentially harmful aquarium species may be difficult to identify based on morphology alone. As such, some prohibited or invasive species may be available for purchase if they are mislabeled as species without restrictions. Here we compare molecular identifications to internet vendors’ identifications for accessions of a popular genus of aquarium plants that are difficult to distinguish morphologically (Myriophyllum; watermilfoils). Specifically, we identified the extensive mislabeling of M. heterophyllum—an invasive species in the northeastern and western US. Furthermore, genotypes of M. heterophyllum found in our aquarium survey have also been found in invasive populations, suggesting their potential introduction through escape from aquaria, water gardens, or nurseries. Two additional taxa were sold under incorrect names. Finally, our survey revealed that Myriophyllum taxa present in the aquarium trade generally have poorly known distributions and ecologies, and therefore their invasive potential is unknown. Our study confirms that molecular identification methods can provide a valuable tool to survey commercial pathways for potentially harmful species that are otherwise difficult to identify.     

Preventing horticultural introductions of invasive plants: potential efficacy of voluntary initiatives

Although prevention is the most cost-effective way to avoid the enormous expenses associated with plant invasions, invasive plants continue to be imported as trade commodities for horticultural use. With very little government regulation of horticultural imports of invasive plants, efforts have turned toward fostering voluntary initiatives to encourage self-regulation by the horticulture trade. Our study takes the first step toward evaluating the potential success of these voluntary initiatives. We conducted a survey of nursery professionals to gauge their perceptions of invasive species, the role of the horticulture trade in invasive plant introductions, and their participation—potential and actual—in preventive measures outlined in the St Louis Voluntary Codes of Conduct for nursery professionals. We found nursery professionals to be highly aware of invasive plants and to accept responsibility as a trade for horticultural introductions. Although only 7% of respondents had heard of the St Louis Voluntary Codes of Conduct, the majority (57%) reported having participated in at least two of seven preventive measures, and most (78%) reported willingness to engage in the majority of preventive measures. We found that several factors significantly predict increased participation in preventive measures, particularly awareness of invasive plants and involvement in trade associations. We also identified incentives and obstacles to participating in preventive behaviors, including “concern for the environment” and “lack of information,” respectively. Our results suggest that participation in voluntary initiatives will improve through increased outreach, and we provide specific recommendations for improving participation in voluntary programs in the horticulture trade.     

Integrating Different Biological Evidence Around Some Microevolutionary Processes: Bottlenecks and Asian-American Arctic Gene Flow in the New World Settlement

Excepting some specific efforts, most of the mainstream debate around the Americas’ settlement has been directed by specialists dealing with partial evidence. Thus, discussions have been confined to particular academic and scientific environments with limited interchange among archeologists, physical anthropologists, linguists, geneticists, geologists, paleontologists, and so on. As a consequence, integrative views about a process that is complex by definition have been scarce and driven by confrontation rather than by a search for common results. Still, an increasing number of specialists are attempting to integrate different types of data. In our view, a proper way to do this is to focus the discussion around evolutionary or cultural processes and the putative patterns that such processes could have generated in the different types of data, which in turn, depend on the nature of the data. In this way, the analyses and conclusions can be interpreted as “model-bound” rather than purely inferential. In this paper, we first provide a brief summary of main differences among the two main sources of biological information—genetics and craniofacial size and shape—along with the main conclusions that the patterns of genetic and craniofacial variation provide. Furthermore, we exemplify the above-mentioned notion by discussing two particular processes and their hypothetical impact on genetic and craniofacial data: the influence of bottlenecks during the early dispersal and a putative zone of gene flow among Asian and American Circum-Arctic populations.     

The effects of serotiny and rainfall-cued dispersal on fitness: bet-hedging in the threatened cactus <Emphasis Type="Italic">Mammillaria pectinifera</Emphasis>

Serotiny—the retention of seeds in the mother plant for over a year—in unpredictable environments may increase the probability that at least some seeds are dispersed during favorable periods. Propagules may be expelled when environmental cues announcing favorable conditions occur, or be gradually released into the environment. This could be a bet-hedging strategy increasing the long-term fitness by reducing interannual variability in reproduction. However, the impact of seed retention on the population dynamics of serotinous species and its contribution to fitness has been barely explored under field conditions. We assessed these issues in the threatened Mammillaria pectinifera, a small globose cactus that gets established only in exceptionally rainy years. This species expels some seeds actively during unusually rainy periods, while dispersing others passively over several years. Dynamics of the seeds in the mother plant over two very contrasting years in terms of precipitation was incorporated into a stochastic matrix model. Seed retention was found to increase significantly the probability that some of the seeds retained in any given year are dispersed within a subsequent rainy period. Active seed-expulsion raises this probability even further. As expected in bet hedgers, seed retention increased fitness in the presence of temporal variability. Active fruit expulsion did not affect fitness, but reduced demographic stochasticity. The incomplete serotiny and fruit expulsion observed is the evolutionary outcome expected for the environment and life-history attributes of the species.     

Azaperone and sudden death of drive net-captured southern chamois

The use of tranquilizers in the capture of southern chamois (Rupicapra pyrenaica) for scientific and/or management purposes (collection of samples, marking, translocations) was studied to improve animal welfare during capture operations. We used clinical findings and a statistical approach to analyze the causes of six incidences of mortality during captures using drive nets and tranquilizers in this species. Hematology and serum biochemistry, pathology, the use of tranquilizers and their dosages, the number of people involved in the capture of the chamois, and the location were all taken into account. The selection of candidate models to explain mortality was conducted using the theoretic information approach. Both observational findings and the models selected suggested that high doses of azaperone and to a lesser extent haloperidol had an effect on mortality rates. The higher mean serum lactate concentrations found in the chamois that died suggests that fatigue levels increased drug sensitivity and provoked the appearance of adverse effects, thereby increasing the probability of death. We conclude that butyrophenones—and especially azaperone—have a low safety margin in the southern chamois, contrary to what has been described for other species.     

Comparing data of different survey methods for sustainable wildlife management in hunting areas: the case of Tarangire–Manyara ecosystem,northern Tanzania

Cost–benefit considerations of wildlife monitoring are essential, particularly, in areas outside national park boundaries, where resources for conducting wildlife censuses are scarce, but that, at the same time, are subject to high pressure for wildlife utilization, such as hunting. Large mammal survey data from various sources were collated and analyzed to investigate which methods are best suited for monitoring purposes at low cost in the Tarangire–Manyara ecosystem, northern Tanzania. Our results indicate that primary data (from aerial and road transects counts) that involve direct species observations, although sometimes very expensive, are required for establishing the status of the target species in terms of density or population size. Concomitantly, secondary data from various sources, such as interviews, hunting quota, and damage reports, obtained over wide areas and over longer periods of time, can provide important information on presence/absence and distribution of species within an area. In addition, the study revealed that hunting quotas set did not correlate with species abundance/numbers from the primary data surveys for most of the large mammals hunted within the ecosystem. For a better conservation and management of wildlife, in particular with respect to the forthcoming formation of Wildlife Management Areas, we propose an integrated approach to wildlife monitoring using primary and secondary data sources through the involvement of local people’s knowledge.     

A consistent terminology for quantifying species diversity? Yes, it does exist

The prevailing terminological confusion around the concept ‘diversity’ has hampered accurate communication and caused diversity issues to appear unnecessarily complicated. In fact, a consistent terminology for phenomena related to (species) diversity is already available. When this terminology is adhered to, diversity emerges as an easily understood concept. It is important to differentiate between diversity itself and a diversity index: an index of something is just a surrogate for the thing itself. The conceptual problem of defining diversity also has to be separated from the practical problem of deciding how to adequately quantify diversity for a community of interest. In practice, diversity can be quantified for any dataset where units of observation (such as individuals) have been classified into types (such as species). All that needs to be known is what proportion of the observed units belong to a type of mean abundance. Diversity equals the inverse of this mean, and it quantifies the effective number of the types of interest. In ecology, interest often (but not always) focuses on species diversity. If the dataset consists of (or gets divided into) subunits, then the total effective number of species (gamma diversity) can be partitioned into the effective number of compositionally distinct subunits (beta diversity) and the mean effective number of species per such subunit (alpha diversity). Species richness is related to species diversity, but they are not the same thing; richness does not take the proportional abundances into account and is therefore the actual—rather than the effective—number of types. Most of the phenomena that have been called ‘beta diversity’ in the past do not quantify an effective number of types, so they should be referred to by names other than ‘diversity’ (for example, species turnover or differentiation).     

Rates of Agonism by Diurnal Lemuroids: Implications for Female Social Relationships

Sterck and colleagues (Behaviour 134:749–774, 1997) focused attention on the evolutionary ecology of female social relationships within and between groups and proposed a model that distinguishes 4 categories of female relationships, which correspond to particular types of intra- and intergroup competition. They emphasized literature on haplorhines in their model because of numerous, detailed studies conducted on a range of species in the wild; in contrast, strepsirrhines such as the lemuroids are poorly represented. We evaluate more closely their classification of lemuroids as Dispersal-Egalitarian using a greater number of species of Lemur, Eulemur, Varecia, Hapalemur, Indri, and Propithecus. For the focal species we found that female philopatry occurs rarely, agonistic rates are relatively low, female dominance hierarchies are not stable and do not exist year-round, and intra- and intergroup female-female competition is infrequent. Therefore, our results support the suggestion that a majority of lemuroid taxa we surveyed correspond to the Dispersal-Egalitarian category with 2 probable exceptions: Lemur catta and Propithecus edwardsi. Because female Lemur catta are philopatric, have year-round dominance hierarchies with female matrilines, exhibit the highest rates of agonism in studied lemuroids, and have frequent intra- and intergroup female-female competition, it would seem that they more closely correspond to the category Resident-Nepotistic. However, maternal Lemur catta rarely support their offspring in agonistic contests and matrilineal rank is not inherited, which leads us to state that the species does not fit into any existing category that explains the nature of female social relationships. The relationships of female Propithecus edwardsi are also a challenge to categorize under the current model because some of their characteristics —typical female dispersal and low agonistic rates— fall into the Dispersal-Egalitarian category, yet other behaviors —intense targeted aggression and stable and year-round female dominance hierarchies— do not.     

Modularity and reliability in the organization of organisms

An organism persists only if it satisfies internal and external constraints. Within the organism networks of processes meet the constraints. In such networks a principle of matching often obtains: the pattern of coupling among processes matches the correlation among constraints. That is, a module—a cluster of coupled processes—meets a constraint. Dissociable modules meet dissociàble constraints. A hierarchy of modules meets a hierarchy of constraints. We have inquired whether such matching is predicted by an optimality criterion in a simple example. We find that in an ensemble of networks with unreliable processes, the networks that meet the constraints with highest reliability obey the principle of matching. The difference in reliability between modular and nonmodular networks that meet the same constraints is a function of the probability of success per process. Our results suggest that this difference is maximal at a probability of success that increases monotonically with the number of processes in the network.     

Commentary: Do we have a consistent terminology for species diversity? The fallacy of true diversity

There is no single best index that can be used to answer all questions about species diversity. Entropy-based diversity indices, including Hill’s indices, cannot account for geographical and phylogenetic structure. While a single diversity index arises if we impose several constraints—most notably that gamma diversity be completely decomposed into alpha and beta diversity—there are many ecological questions regarding species diversity for which it is counterproductive, requiring decomposability. Non-decomposable components of gamma diversity may quantify important intrinsic ecological properties, such as resilience or nestedness.     

Flower colours along an alpine altitude gradient, seen through the eyes of fly and bee pollinators

Alpine flowers face multiple challenges in terms of abiotic and biotic factors, some of which may result in selection for certain colours at increasing altitude, in particular the changing pollinator species composition, which tends to move from bee-dominated at lower elevations to fly-dominated in high-alpine regions. To evaluate whether growing at altitude—and the associated change in the dominant pollinator groups present—has an effect on the colour of flowers, we analysed data collected from the Dovrefjell National Park in Norway. Unlike previous studies, however, we considered the flower colours according to ecologically relevant models of bee and fly colour vision and also their physical spectral properties independently of any colour vision system, rather than merely looking at human colour categories. The shift from bee to fly pollination with elevation might, according to the pollination syndrome hypothesis, lead to the prediction that flower colours should shift from more bee-blue and UV-blue flowers (blue/violet to humans, i.e. colours traditionally associated with large bee pollinators) at low elevations to more bee-blue-green and green (yellow and white to humans—colours often linked to fly pollination) flowers at higher altitude. However, although there was a slight increase in bee-blue-green flowers and a decrease in bee-blue flowers with increasing elevation, there were no statistically significant effects of altitude on flower colour as seen either by bees or by flies. Although flower colour is known to be constrained by evolutionary history, in this sample we also did not find evidence that phylogeny and elevation interact to determine flower colours in alpine areas. Handling editor: Neal Williams     

Ultrastructural changes of the midgut epithelium in Isohypsibius granulifer granulifer Thulin, 1928 (Tardigrada: Eutardigrada) during oogenesis

The midgut epithelium of Isohypsibius granulifer granulifer (Eutardigrada) is composed of columnar digestive cells. At its anterior end, a group of cells with cytoplasm which differs from the cytoplasm of digestive cells is present. Probably, those cells respond to crescent-like cells (midgut regenerative cells) described for some tardigrade species. Their mitotic divisions have not been observed. We analyzed the ultrastructure of midgut digestive cells in relation to five different stages of oogenesis (previtellogenesis, beginning of the vitellogenesis, vitellogenesis—early choriogenesis, vitellogenesis—middle choriogenesis, late choriogenesis). In the midgut epithelium cells, the gradual accumulation of glycogen granules, lipid droplets and structures of varying electron density occurs. During vitellogenesis and choriogenesis, in the cytoplasm of midgut cells we observed the increasing number of organelles which are responsible for the intensive synthesis of lipids, proteins and saccharides such as cisterns of endoplasmic reticulum and Golgi complexes. At the end of oogenesis, autophagy also intensifies in midgut epithelial cells, which is probably caused by the great amount of reserve material. Midgut epithelium of analyzed species takes part in the yolk precursor synthesis.     

Maximizing biodiversity, information and sustainability

Numerous global changes—notably anthropogenic extinction—force reconsideration of our management practices and the ways we regulate human influence in today’s world. Here, I define management to maximize biodiversity and illustrate the science that provides information to set goals for such management. Maximizing biodiversity simultaneously achieves sustainability and systemic health by avoiding the abnormal or pathological. The normal or sustainable are determined through the use of empirical integrative patterns to objectively account for the complexity of systems within which we find ourselves as a species. The science that reveals these integrative patterns provides measures of problems that can be solved by maximizing biodiversity—problems heretofore recognized only qualitatively. I use the Shannon-Weiner information index to test, and, with no surprise, reject the null hypothesis that there is no direct anthropogenic effect on biodiversity. The results of this science serve as examples of the kind of information most useful for guiding management and illustrate maximized biodiversity as a standard for management. Reference points based on maximized biodiversity are preferable to statistical parameters in meeting the objective of avoiding the abnormal or pathological in our interactions with other species, ecosystems and the biosphere. Management to maximize biodiversity is implemented by modifying human interactions with other biotic systems to achieve consistency in such interactions by mimicking natural role models of sustainability. Human influence is a significant factor in today’s world and the magnitude of such influence is illustrated by comparing humans with other species.