Institut für Ökologie, Evolution und Diversität
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Importance of latrine communication in European rabbits shifts along a rural–to–urban gradient
(2016)
Background: Information transfer in mammalian communication networks is often based on the deposition of excreta in latrines. Depending on the intended receiver(s), latrines are either formed at territorial boundaries (between-group communication) or in core areas of home ranges (within-group communication). The relative importance of both types of marking behavior should depend, amongst other factors, on population densities and social group sizes, which tend to differ between urban and rural wildlife populations. Our study is the first to assess (direct and indirect) anthropogenic influences on mammalian latrine-based communication networks along a rural-to-urban gradient in European rabbits (Oryctolagus cuniculus) living in urban, suburban and rural areas in and around Frankfurt am Main (Germany).
Results: The proportion of latrines located in close proximity to the burrow was higher at rural study sites compared to urban and suburban ones. At rural sites, we found the largest latrines and highest latrine densities close to the burrow, suggesting that core marking prevailed. By contrast, latrine dimensions and densities increased with increasing distance from the burrow in urban and suburban populations, suggesting a higher importance of peripheral marking.
Conclusions: Increased population densities, but smaller social group sizes in urban rabbit populations may lead to an increased importance of between-group communication and thus, favor peripheral over core marking. Our study provides novel insights into the manifold ways by which man-made habitat alterations along a rural-to-urban gradient directly and indirectly affect wildlife populations, including latrine-based communication networks.
Erratum to doi:10.1186/s13071-016-1853-2
Background: Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe.
Methods: In the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements.
Results: Both species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus.
Conclusions: Species distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies.
Janthinobacterium and Duganella are well-known for their antifungal effects. Surprisingly, almost nothing is known on molecular aspects involved in the close bacterium-fungus interaction. To better understand this interaction, we established the genomes of 11 Janthinobacterium and Duganella isolates in combination with phylogenetic and functional analyses of all publicly available genomes. Thereby, we identified a core and pan genome of 1058 and 23,628 genes. All strains encoded secondary metabolite gene clusters and chitinases, both possibly involved in fungal growth suppression. All but one strain carried a single gene cluster involved in the biosynthesis of alpha-hydroxyketone-like autoinducer molecules, designated JAI-1. Genome-wide RNA-seq studies employing the background of two isolates and the corresponding JAI-1 deficient strains identified a set of 45 QS-regulated genes in both isolates. Most regulated genes are characterized by a conserved sequence motif within the promoter region. Among the most strongly regulated genes were secondary metabolite and type VI secretion system gene clusters. Most intriguing, co-incubation studies of J. sp. HH102 or its corresponding JAI-1 synthase deletion mutant with the plant pathogen Fusarium graminearum provided first evidence of a QS-dependent interaction with this pathogen.
In China and other countries of East Asia, so-called Ling-zhi or Reishi mushrooms are used in traditional medicine since several centuries. Although the common practice to apply the originally European name ‘Ganoderma lucidum’ to these fungi has been questioned by several taxonomists, this is still generally done in recent publications and with commercially cultivated strains. In the present study, two commercially sold strains of ‘G. lucidum’, M9720 and M9724 from the company Mycelia bvba (Belgium), are compared for their fruiting body (basidiocarp) morphology combined with molecular phylogenetic analyses, and for their secondary metabolite profile employing an ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–ESIMS) in combination with a high resolution electrospray ionization mass spectrometry (HR-ESI-MS). According to basidiocarp morphology, the strain M9720 was identified as G. lucidum s.str. whereas M9724 was determined as Ganoderma lingzhi. In molecular phylogenetic analyses, the M9720 ITS and beta-tubulin sequences grouped with sequences of G. lucidum s.str. from Europe whereas those from M9724 clustered with sequences of G. lingzhi from East Asia. We show that an ethanol extract of ground basidiocarps from G. lucidum (M9720) contains much less triterpenic acids than found in the extract of G. lingzhi (M9724). The high amount of triterpenic acids accounts for the bitter taste of the basidiocarps of G. lingzhi (M9724) and of its ethanol extract. Apparently, triterpenic acids of G. lucidum s.str. are analyzed here for the first time. These results demonstrate the importance of taxonomy for commercial use of fungi.
Background: One aspect of premating isolation between diverging, locally-adapted population pairs is female mate choice for resident over alien male phenotypes. Mating preferences often show considerable individual variation, and whether or not certain individuals are more likely to contribute to population interbreeding remains to be studied. In the Poecilia mexicana-species complex different ecotypes have adapted to hydrogen sulfide (H2S)-toxic springs, and females from adjacent non-sulfidic habitats prefer resident over sulfide-adapted males. We asked if consistent individual differences in behavioral tendencies (animal personality) predict the strength and direction of the mate choice component of premating isolation in this system.
Results: We characterized focal females for their personality and found behavioral measures of ‘novel object exploration’, ‘boldness’ and ‘activity in an unknown area’ to be highly repeatable. Furthermore, the interaction term between our measures of exploration and boldness affected focal females’ strength of preference (SOP) for the resident male phenotype in dichotomous association preference tests. High exploration tendencies were coupled with stronger SOPs for resident over alien mating partners in bold, but not shy, females. Shy and/or little explorative females had an increased likelihood of preferring the non-resident phenotype and thus, are more likely to contribute to rare population hybridization. When we offered large vs. small conspecific stimulus males instead, less explorative females showed stronger preferences for large male body size. However, this effect disappeared when the size difference between the stimulus males was small.
Conclusions: Our results suggest that personality affects female mate choice in a very nuanced fashion. Hence, population differences in the distribution of personality types could be facilitating or impeding reproductive isolation between diverging populations depending on the study system and the male trait(s) upon which females base their mating decisions, respectively.
Non-Timber Forest Products (NTFPs) make a major contribution to the livelihoods and diets of rural households in the savanna ecosystems of West Africa. However, land use change and climatic variability might affect their availability in the future. Based on a survey among 227 households in Northern Benin, we investigated local substitution patterns for the seeds of the three socio-economically most important NTFP-species in the region, Vitellaria paradoxa, Adansonia digitata and Parkia biglobosa, being major sources for protein, fat, and micronutrients in local daily diets. Our study compared substitution patterns between, firstly, three income groups, to assess whether a households’ socio-economic status has an influence on the choice of surrogates (low cost vs. more costly options). Secondly, we compared substitution patterns between the five major ethnic groups in the study region (the Fulani, the Bariba, the Ditammarie, the Kabiyé and the Yom). The choice of substitutes differed significantly across income groups. However, the poorest households clearly show to be the most vulnerable: up to 30 % of the sampled households stated they would lack an adequate replacement for the NTFPs in question. Furthermore, ethnic affiliation showed to have a considerable impact on the preferred alternative products due to underlying cultural traditions of plant use. Subsequently, aiming at maintaining – and enhancing – the local supply of V. paradoxa, P. biglobosa and A. digitata in order to secure their contributions to local diets, local land use policy should have a particular focus on their ethnic-conditioned use and particularly the specific requirements of the poorest community members.
Background: Bacteria within the genus Photorhabdus maintain mutualistic symbioses with nematodes in complicated lifecycles that also involves insect pathogenic phases. Intriguingly, these bacteria are rich in biosynthetic gene clusters that produce compounds with diverse biological activities. As a basis to better understand the life cycles of Photorhabdus we sequenced the genomes of two recently discovered representative species and performed detailed genomic comparisons with five publically available genomes.
Results: Here we report the genomic details of two new reference Photorhabdus species. By then conducting genomic comparisons across the genus, we show that there are several highly conserved biosynthetic gene clusters. These clusters produce a range of bioactive small molecules that support the pathogenic phase of the integral relationship that Photorhabdus maintain with nematodes.
Conclusions: Photorhabdus contain several genetic loci that allow them to become specialist insect pathogens by efficiently evading insect immune responses and killing the insect host.
The use of parasites as biological tags for discrimination of fish stocks has become a commonly used approach in fisheries management. Metazoan parasite community analysis and anisakid nematode population genetics based on a mitochondrial cytochrome marker were applied in order to assess the usefulness of the two parasitological methods for stock discrimination of beaked redfish Sebastes mentella of three fishing grounds in the North East Atlantic. Multivariate, model-based approaches demonstrated that the metazoan parasite fauna of beaked redfish from East Greenland differed from Tampen, northern North Sea, and Bear Island, Barents Sea. A joint model (latent variable model) was used to estimate the effects of covariates on parasite species and identified four parasite species as main source of differences among fishing grounds; namely Chondracanthus nodosus, Anisakis simplex s.s., Hysterothylacium aduncum, and Bothriocephalus scorpii. Due to its high abundance and differences between fishing grounds, Anisakis simplex s.s. was considered as a major biological tag for host stock differentiation. Whilst the sole examination of Anisakis simplex s.s. on a population genetic level is only of limited use, anisakid nematodes (in particular, A. simplex s.s.) can serve as biological tags on a parasite community level. This study confirmed the use of multivariate analyses as a tool to evaluate parasite infra-communities and to identify parasite species that might serve as biological tags. The present study suggests that S. mentella in the northern North Sea and Barents Sea is not sub-structured.
The Asian tiger mosquito Aedes albopictus, native to South East Asia, is listed as one of the worst invasive vector species worldwide. In Europe the species is currently restricted to Southern Europe, but due to the ongoing climate change, Ae. albopictus is expected to expand its potential range further northwards. In addition to modelling the habitat suitability for Ae. albopictus under current and future climatic conditions in Europe by means of the maximum entropy approach, we here focused on the drivers of the habitat suitability prediction. We explored the most limiting factors for Aedes albopictus in Europe under current and future climatic conditions, a method which has been neglected in species distribution modelling so far. Ae. albopictus is one of the best-studied mosquito species, which allowed us to evaluate the applied Maxent approach for most limiting factor mapping. We identified three key limiting factors for Ae. albopictus in Europe under current climatic conditions: winter temperature in Eastern Europe, summer temperature in Southern Europe. Model findings were in good accordance with commonly known establishment thresholds in Europe based on climate chamber experiments and derived from the geographical distribution of the species. Under future climatic conditions low winter temperature were modelled to remain the most limiting factor in Eastern Europe, whereas in Central Europe annual mean temperature and summer temperatures were modelled to be replaced by summer precipitation, respectively, as most limiting factors. Changes in the climatic conditions in terms of the identified key limiting factors will be of great relevance regarding the invasive potential of the Ae. albopictus. Thus, our results may help to understand the key drivers of the suggested range expansion under climate change and may help to improve monitoring programmes. The applied approach of investigating limiting factors has proven to yield valuable results and may also provide valuable insights into the drivers of the prediction of current and future distribution of other species. This might be particularly interesting for other vector species that are of increasing public health concerns.