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Many of the world’s most biodiverse regions are found in the poorest and second most populous continent of Africa; a continent facing exceptional challenges. Africa is projected to quadruple its population by 2100 and experience increasingly severe climate change and environmental conflict—all of which will ravage biodiversity. Here we assess conservation threats facing Africa and consider how these threats will be affected by human population growth, economic expansion, and climate change. We then evaluate the current capacity and infrastructure available to conserve the continent’s biodiversity. We consider four key questions essential for the future of African conservation: (1) how to build societal support for conservation efforts within Africa; (2) how to build Africa’s education, research, and management capacity; (3) how to finance conservation efforts; and (4) is conservation through development the appropriate approach for Africa? While the challenges are great, ways forward are clear, and we present ideas on how progress can be made. Given Africa’s current modest capacity to address its biodiversity crisis, additional international funding is required, but estimates of the cost of conserving Africa’s biodiversity are within reach. The will to act must build on the sympathy for conservation that is evident in Africa, but this will require building the education capacity within the continent. Considering Africa’s rapidly growing population and the associated huge economic needs, options other than conservation through development need to be more effectively explored. Despite the gravity of the situation, we believe that concerted effort in the coming decades can successfully curb the loss of biodiversity in Africa.
Many ethicists consider the rule of nonmaleficence – Do no harm! – to be the most fundamental ethical rule and key to ethics. This rule is taken as the foundation of the present work. I argue that any entity, that can be harmed, ought to be morally considered. Only those entities can be harmed that are inherently goal-directed or striving – in other words, that possess a telos. The reason is that by constantly acting in ways to preserve their being and to prevent their own not-being, goal-directed entities express that they value their own good. To harm such a goal-directed entity therefore means to act against the values and the good of it. The argument so far supports ethical biocentrism, that is, the view that all living, goal-directed beings are harmable, possess interests, and are, thus, morally considerable, while non-living beings are not. Yet, I digress from classical biocentrism since I conclude, based on analysis of evolutionary and biological findings, that the locus of goal-directedness and potential harm is also, if not foremost, situated in genes. Within many species, individual organisms sacrifice themselves for the betterment of their descendants like in praying mantises where males sacrifice themselves and are eaten by the female during copulation. This shows that it is not necessarily the organism as an individual which follows its own interests and goals. Individual organisms are – to a high degree – “directed” by their genes. Even in highly developed animals, genes play a significant role in the goal-directedness of the individuals. An adult human organism, for example, consists of trillions of individual cells. However, all these cells are derived from a single cell – the fertilized egg. Each of our lives begins with a single cell that contains almost all information to finally form our functioning body. Where do all the instructions, the goal-directedness come from to finally form an adult organism if not from the genes contained in this first cell, the zygote? It is the genes of each zygote that contain a set of information for making the appropriate adult. Organisms are largely programmed to do everything necessary to stay in existence, to survive, and finally to pass on their genes successfully – either by reproducing or by helping close relatives that carry a similar set of genes. The main interests of genes lie in their continued existence. This necessitates reproduction since the gene-carrying organisms will inevitably die. Single genes, though, are difficult to morally consider directly since they perform entirely in and through individual organisms. Without the individual organisms, genes cannot survive. The good news for ethics is that the interests of genes and organism usually converge: individual organisms try to survive – as do their genes. In practice, it thus makes much more sense to give moral attention to entire organisms instead of single genes. An advantage of the gene-centric ethical theory proposed here is that the moral relevance of future generations and species can be “directly” justified: Since genes have an interest in their continued existence (in the form of identical copies), they would be harmed if future generations were doomed to inexistence. Within a species with many individuals, each gene is likely to be represented in many organisms. The smaller the gene pool of a species gets, the less likely is the existence of the same gene and, therefore, the less likely is the fulfillment of its fundamental interests. Hence, saving one of the last individuals of an endangered species would be ethically preferable to saving an individual of a populous species. Unfortunately, moral conflicts are abundant – not only concerning biodiversity conservation. We often have to choose between harming either entity A or entity B – for example in the daily questions of food and eating. In such cases, a strictly egalitarian theory (especially an egalitarian biocentric one) would be no real help and without any guiding power. Therefore, on a second level of morality, we have to include additional criteria that help to minimize the overall harm. For these criteria to be objective, universalizable, and thus moral ones, I apply a number of widely accepted ethical principles like the principle of proportionality, impartiality, self-defense, and universalizability. By recurring to these principles, I identify a set of morally relevant criteria for a fair resolution of moral conflict situations which help to minimize the overall harm done. The identified criteria are: (phylogenetic) nearness, endangerment, r- or K-selected species, evolutionary distinctiveness, ability to regrow and to regenerate, pain-susceptibility, and ecosystematic role. In sum, my gene-centric environmental ethical theory provides numerous reasons and arguments for biodiversity conservation – for protecting genes, organisms, species, and ecosystems alike – without neglecting the needs of humans.
Samples of two duckweed species, Spirodela polyrhiza and Lemna minor, were collected around small ponds and investigated concerning the question of whether natural populations of duckweeds constitute a single clone, or whether clonal diversity exists. Amplified fragment length polymorphism was used as a molecular method to distinguish clones of the same species. Possible intraspecific diversity was evaluated by average-linkage clustering. The main criterion to distinguish one clone from another was the 95% significance level of the Jaccard dissimilarity index for replicated samples. Within natural populations of L. minor, significant intraspecific genetic differences were detected. In each of the three small ponds harbouring populations of L. minor, based on twelve samples, between four and nine distinct clones were detected. Natural populations of L. minor consist of a mixture of several clones representing intraspecific biodiversity in an aquatic ecosystem. Moreover, identical distinct clones were discovered in more than one pond, located at a distance of 1 km and 2.4 km from each other. Evidently, fronds of L. minor were transported between these different ponds. The genetic differences for S. polyrhiza, however, were below the error-threshold of the method within a pond to detect distinct clones, but were pronounced between samples of two different ponds.
Metabarcoding of invertebrate-derived DNA (iDNA) is increasingly used to describe vertebrate diversity in terrestrial ecosystems. Fly iDNA has also shown potential as a tool for detecting pathogens. Combining these approaches makes fly iDNA a promising tool for understanding the ecology and distribution of novel pathogens or emerging infectious diseases. Here, we use fly iDNA to explore the geographic distribution of Bacillus cereus biovar anthracis (Bcbva) along a gradient from the forest within Taï National Park, Côte d'Ivoire, out to surrounding villages. We tested fly pools (N = 100 pools of 5 flies) collected in the forest (N = 25 pools), along the forest edge (N = 50 pools), and near surrounding villages (N = 25 pools) for Bcbva. Using the same iDNA, we sought to reconstruct fly and mammal communities with metabarcoding, with the aim of investigating potential links with Bcbva detection. We detected Bcbva in 5/100 fly pools and positivity varied significantly across the habitat types (forest = 4/25, edge = 1/50, village = 0/25). It was possible to culture Bcbva from all positive fly pools, confirming their positivity, while sequencing of their whole genomes revealed a considerable portion of known genomic diversity for this pathogen. iDNA generated data about the mammal and fly communities in these habitats, revealing the highest mammal diversity in the forest and considerable changes in fly community composition along the gradient. Bcbva host range estimates from fly iDNA were largely identical to the results of long-term carcass monitoring efforts in the region. We show that fly iDNA can generate data on the geographic distribution and host range of a pathogen at kilometer scales, as well as reveal the pathogen's phylogenetic diversity. Our results highlight the power of fly iDNA for mammal biomonitoring and pathogen surveillance.
The present work focusses on the mosquito populations of two zoological gardens in Germany with the aim to better understand mosquito biology of native species and to contribute to a greater awareness of mosquito and mosquito-borne disease agent surveillance in zoos. For this purpose, data on species composition, blood meal patterns and mosquito-borne pathogens were analysed. The investigated zoological gardens differed not only in their sizes and animal stocks, but also in their surrounding environments. The 160 ha Tierpark Berlin is located in a densely populated urban area, while the 15 ha Zoological Garden Eberswalde is surrounded by forest.
To gain an overview about the mosquito fauna of both zoos, adult specimens were caught by aspirating and EVS-trapping during the 2016 season. In addition, larval stages were collected from their breeding sites located in the zoo areas. In total, 2,257 mosquitoes were sampled, belonging to 20 taxa. Seasonal differences between the zoos were documented, both in terms of species composition and the relative abundance of mosquito species collected. As the studied zoos were located in the same climatic region and both locations provided similar breeding sites, differences in species composition were attributed to the entry of mosquitoes from surrounding landscapes. Influencing factors could have been the different sizes of the zoos and variations in the potential host animal populations.
According to the vector potential of most frequently collected taxa in the Zoological Garden Eberswalde (Annulipes Group, Culiseta annulata), TAHV, USUV, WNV, filariae and avian malaria parasites appear to have the highest risk of being transmitted at this location. In the Tierpark Berlin, Aedes vexans was the most frequently collected mosquito species, suggesting a theoretical risk for the transmission of a broader spectrum of pathogens due to covered vector competences. Pathogens such as BATV, SINV, TAHV, USUV and filarial worms could be of major importance regarding transmission risk to zoo animals, as they had previously been found to circulate Germany. In addition, avian malaria parasites represent a considerable risk for susceptible exotic bird species in Berlin.
Since the blood-feeding behaviour of vector-competent mosquito species has a major influence on the transmission of a mosquito-associated pathogen, the analysis of blood meal patterns is crucial to better understand vector-pathogen cycles. Therefore, blood meals of blood-fed mosquitoes caught in 2016 and 2017 by aspirating and EVS-trapping in the Tierpark Berlin and the Zoological Garden Eberswalde were analysed. The aim was to investigate to what extent native mosquito species accept exotic zoo animals, wild native animals and humans as blood hosts. In addition, it was examined whether the collected species are generalists or specialists when selecting vertebrates for blood feeding.
A total of 405 blood-fed mosquitoes from 16 taxa were collected. The genetic analysis of blood meals identified 56 host species, which – in addition to humans – mainly originated from mammals of the zoo animal populations. In agreement with the previous study on the mosquito fauna of the Tierpark Berlin and the Zoological Garden Eberswalde, the analysis of blood meals also showed differences between the two zoos. In the smaller Zoological Garden Eberswalde, a higher number of blood-fed mosquitoes was collected than in the Tierpark Berlin, probably caused by a higher host density in Eberswalde, which may have led to an overall higher mosquito density. However, no differences between both zoos were observed with respect to the blood feeding behaviour of the analysed mosquito species: Mosquitoes of both locations were rather generalistic, although species could be grouped according their blood meals into 'amphibian', 'non-human mammal' and, ‘non-human mammal and human' feeding species. The more random selection of hosts could indicate a low probability of effective pathogen transmission by applying the 'dilution effect'. Notwithstanding, since wild animals have also been accepted as hosts, pathogen transmission by bridge vectors from one vertebrate group to another could be relevant in the sampled zoos.
Adult mosquito specimens collected in 2016 and 2017 were screened for filarial nematodes, avian Haemosporidia and mosquito-borne viruses. Dirofilaria repens was detected in a mosquito from the Zoological Garden Eberswalde. Mosquitoes from Berlin and Eberswalde were tested positive for the nematode species S. tundra. Sindbis virus was found in a mosquito pool collected in the Tierpark Berlin, while no mosquito-associated viruses were detected in specimens collected in the Zoological Garden Eberswalde. Mosquitoes from both zoos were positive for the haemosporidian parasites Haemoproteus sp. and Leucocytozoon sp., and one documentation was made for avian Plasmodium sp. in the Tierpark Berlin.
The identified pathogens have the potential to cause disease in captive and wild animals, and some of them also in humans. Most of the mosquitoes tested positive had been collected in July, suggesting a high infection risk during this month. Since most pathogen detections were made from species belonging to the Cx. pipiens complex, species of this complex seem to be most relevant in the studied zoos when it comes to mosquito-borne pathogen transmission. Although mosquitoes are no proven vectors of most of the avian malaria parasite genera found, evidence for Haemoproteus sp. and Leucozytozoon sp. demonstrated a high prevalence of avian malaria parasites in the zoos.
In summary, the results of the three studies indicate regional differences both in the mosquito species composition and in the occurrence of mosquito-borne pathogens. However, no differences were found between the mosquito communities of both zoos concerning their blood feeding behaviour, suggesting that the general behaviour of the insects is location-independent.
Several potential disease agents were found in the collected mosquitoes, although not at high abundances. Whether these pathogens were found by chance in the two zoos or whether the particular zoo environment is a hot spot of arthropod-borne pathogens cannot be determined with the studies conducted. Nonetheless, it seems clear that zoological gardens are attractive to mosquito females not only in their search for breeding sites, but also when looking for blood hosts and places for mating or resting. These advantageous conditions also attract mosquito species that have their larval habitats outside the zoological gardens, which is why elimination of breeding sites on the zoo premises alone will not necessarily keep away all mosquitoes.
A closer collaboration between zoological gardens and entomologists could be beneficial for both. Zoo officials could benefit from being able to identify potential arthropod vectors on the zoo grounds and receiving information on circulating arthropod-borne disease agents, as well as on the animal species susceptible to those. For entomologists, zoological gardens are ideal research locations, as they provide an environment with a high diversity of habitats and potential blood hosts for haematophagous arthropods in a confined space.
Studying mosquito biology will become even more significant in the future, since in a world that is getting smaller, both potential vectors and pathogens are regularly introduced into areas where they did not occur before. Therefore, it would be desirable if more studies targeting ecological as well as infectiological aspects of vector species in zoological gardens in Germany were carried out.