Abundance signals of amphibians and reptiles indicate strong edge effects in Neotropical fragmented forest landscapes

Fragmentation and habitat loss contribute considerably to global declines of amphibians and reptiles. However, few studies focus on forest edges, created during the fragmentation process, as proximate drivers of the local demographic structure of populations. Here, we use abundance data of amphibians and reptiles to study their responses to forest edges in nine fragmented forested landscapes of the Neotropics. Species-specific abundance data were collected in plots established at varying distances from their respective nearest forest edge. We tested for edge effects on the abundance of species, and used curve clustering techniques to group species with similar edge responses, i.e. species with either increasing or decreasing abundance from the matrix towards the forest interior. We also grouped species that showed no change in abundance with respect to the nearest forest edge and those whose abundance response was unimodal, peaking in either forest habitat or the surrounding matrix habitat. We found that 96% of all amphibians and 90% of all reptiles showed an edge response, with the abundance of 74.5% of amphibians and 57.3% of reptiles decreasing with increasing proximity to forest edges. However, species-specific edge effects were not always consistent, with some species having opposite edge responses when measured in different landscapes. The depth of edge effects exhibited by forest species, i.e. species that increased in abundance in the forest interior, extended up to one kilometre away from forest edges. We show that the median edge effect on forest species extends to 250 m within the forest interior, indicating that tropical forest patches with a mean diameter < 500 m (minimum area ≈ 78 ha) are unsuitable for half of forest-dependent species considered in this study

Soil spore bank in <em>Tuber melanosporum</em>: up to 42% of fruitbodies remain unremoved in managed truffle grounds

International audienceFungi fruiting hypogeously are believed to form spore banks in soil especially because some fruitbodies are not removed by animals. However, little is known on the proportion of fruitbodies that are not removed by animals. We took advantage of the brûlé phenomenon, which allows delineation of the mycelium distribution, to assess the proportion of unremoved black truffle (Tuber melanosporum) fruitbodies in the context of plantations where fruitbodies are actively sought and harvested by truffle growers. We inspected portions of the brûlés after the harvest season to find unremoved fruitbodies. On average, from six truffle grounds in which a total of 38 brûlés were investigated, unremoved fruitbodies represented 33% of the whole fruitbody production (42% when averaging all the brûlés). We discuss this value and its high variability among truffle grounds. Beyond the local and variable accidental reasons that may lead to this high proportion, we speculate that the formation of some undetectable fruitbodies may be under selection pressure, given the reproductive biology of T. melanosporum

Reproductive biology of the black truffle <em>Tuber melanosporum</em>: contrasting ecologies of the two parents

International audienceThe black truffle Tuber melanosporum is an ectomycorrhizal ascomycete of commercial value. Few is known about the reproductive biology of this famous edible mushroom. It is potentially hermaphroditic but reproduction – i.e. formation of the fruitbody (asco-carp) and production of meiotic spores (ascospores) within the later – requires mating between two individuals with opposite mating types. At fruiting, a maternal parent forms the ascocarp, whereas the paternal one only leaves genes in the ascospores. In addition, beyond ascocarps, maternal genotypes also form surrounding ectomycorrhizas, suggesting that they are established as tree symbiont. We summarize here novelties issuing from five years of sampling over France. In order to characterize the genetic structure of populations for both parents, we conducted gen-otyping analyses using 12 microsatellites to characterize maternal and paternal geno-types in ascocarps from seven truffle grounds. This revealed high inbreeding and a strong isolation by distance for maternal and paternal genotypes, ruling out the possibil-ity of gametic gene flow. Maternal individuals were bigger and more perennial than pa-ternal ones, more numerous and transient. Paternal genotypes were never found on sur-rounding ectomycorrhizas. This suggests that the two partners have different develop-ments and niches. We also investigated herbaceous plant roots as a potential niche for the two paternal partners by barcoding and, when possible, by genotyping T. melanosporum from these roots. Although the black truffle infects the herbaceous plants of truffle grounds, only maternal genotypes were again found here. We thus suggest that germinating asco-spores could act as paternal parent

Reproductive biology of the black truffle Tuber melanosporum: contrasting ecologies of the two parents

The black truffle Tuber melanosporum is an ectomycorrhizal ascomycete of commercial value. Few is known about the reproductive biology of this famous edible mushroom. It is potentially hermaphroditic but reproduction – i.e. formation of the fruitbody (asco-carp) and production of meiotic spores (ascospores) within the later – requires mating between two individuals with opposite mating types. At fruiting, a maternal parent forms the ascocarp, whereas the paternal one only leaves genes in the ascospores. In addition, beyond ascocarps, maternal genotypes also form surrounding ectomycorrhizas, suggesting that they are established as tree symbiont. We summarize here novelties issuing from five years of sampling over France. In order to characterize the genetic structure of populations for both parents, we conducted gen-otyping analyses using 12 microsatellites to characterize maternal and paternal geno-types in ascocarps from seven truffle grounds. This revealed high inbreeding and a strong isolation by distance for maternal and paternal genotypes, ruling out the possibil-ity of gametic gene flow. Maternal individuals were bigger and more perennial than pa-ternal ones, more numerous and transient. Paternal genotypes were never found on sur-rounding ectomycorrhizas. This suggests that the two partners have different develop-ments and niches. We also investigated herbaceous plant roots as a potential niche for the two paternal partners by barcoding and, when possible, by genotyping T. melanosporum from these roots. Although the black truffle infects the herbaceous plants of truffle grounds, only maternal genotypes were again found here. We thus suggest that germinating asco-spores could act as paternal parent

Black Truffle, a Hermaphrodite with Forced Unisexual Behaviour

The life cycle of the black truffle (Tuber melanosporum) includes a mating before sporulation: although the species is hermaphroditic, mating turns out to involve parents with very different features, that mostly behave as male or female only, suggesting that this species undergoes forced dioecism

Data from: Colonization and extinction dynamics among the plant species at tree bases in Paris (France)

1. In cities, trees growing along streets could play an important ecological role for spontaneous plants that grow at their bases. For example, these trees could represent corridors that allow species to move in the urban matrix by potentially connecting large green spaces (e.g., parks, gardens, etc.) We considered sets of urban trees in 15 streets as metapopulations for 15 plant species. Our objective was to determine the factors influencing the dynamics of colonization and extinction of populations based on the distance of the streets from green spaces and the biological traits of each species. 2. The species in 1,324 tree bases of the Bercy district of Paris were surveyed annually from 2009 to 2015. For each species and each street, we used SPOMSIM software to identify the best-fit metapopulation model: the propagule rain model (PRM), Levins model (LM), and the PRM and LM with a fixed extinction or a rescue effect. 3. The results demonstrated that the species more often conformed to the PRM in streets near green spaces, which suggested that green spaces could act as the sources for the populations in those streets. Species with seeds with long-term persistence more often conformed to the PRM, indicating that a soil seed bank helps species invade entire streets. Finally, a higher percentage of species with a short height conformed to models with a rescue effect, which indicated that those species resisted the effects of weeding by the city technical services more often than taller species. 4. Synthesis and applications. This study showed how the biological traits of species and the geography of the district determine the dynamics of the plants in the streets, and the results may provide important information for biodiversity management in cities

Truffe en quête de pères : un champignon à l’orientation sexuelle forcée, et pas encore domestiqué !

Truffe en quête de pères : un champignon à l’orientation sexuelle forcée, et pas encore domestiqué

Data of the results of SPOMSIM modeling

Features of the 15 species and 15 streets for which population dynamics was modeled and SPOMSIM modeling results

Quelques considérations sur le réensemencement par ascospores des truffières à Tuber melanosporum

Quelques considérations sur le réensemencement par ascospores des truffières à [i]Tuber melanosporum[/i

Is <em>Tuber melanosporum</em> colonizing the roots of herbaceous, non-ectomycorrhizal plants?

International audienceThe ectomycorrhizal Tuber melanosporum forms edible fruit-bodies after mating between two haploid parents: a maternal individual, which feeds the fruit-body and colonizes surrounding ectomycorrhizas, and a paternal one hitherto undetected around fruit-bodies. Several other aspects of T. melanosporum ecology remain unclear, such as the formation of a brûlé around the mycelium, i.e. patches where plant growth is impaired. Here, we test the hypothesis that T. melanosporum, and specifically paternal individuals, is present on the roots of herbaceous, non-ectomycorrhizal plants of the brûlé. Specific primers detected T. melanosporum on 78.9% of the plant individuals investigated (89.7% of the 80 species considered), and metabarcoding confirmed its presence on 46 of the 70 plant individuals investigated. Genotyping with 13 microsatellites detected maternal individuals of nearby fruit-bodies, but not paternal individuals, whose niche thus remains elusive. We discuss the possibility that T. melanosporum is also a root endophyte in non-ectomycorrhizal plants