Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Ambio ; 49(1): 85-97, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31055795

RESUMEN

Retention forestry implies that biological legacies like dead and living trees are deliberately selected and retained beyond harvesting cycles to benefit biodiversity and ecosystem functioning. This model has been applied for several decades in even-aged, clearcutting (CC) systems but less so in uneven-aged, continuous-cover forestry (CCF). We provide an overview of retention in CCF in temperate regions of Europe, currently largely focused on habitat trees and dead wood. The relevance of current meta-analyses and many other studies on retention in CC is limited since they emphasize larger patches in open surroundings. Therefore, we reflect here on the ecological foundations and socio-economic frameworks of retention approaches in CCF, and highlight several areas with development potential for the future. Conclusions from this perspective paper, based on both research and current practice on several continents, although highlighting Europe, are also relevant to other temperate regions of the world using continuous-cover forest management approaches.


Asunto(s)
Ecosistema , Agricultura Forestal , Biodiversidad , Conservación de los Recursos Naturales , Europa (Continente) , Bosques , Árboles
2.
PLoS One ; 14(4): e0214889, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30995262

RESUMEN

Atractaspidines are poorly studied, fossorial snakes that are found throughout Africa and western Asia, including the Middle East. We employed concatenated gene-tree analyses and divergence dating approaches to investigate evolutionary relationships and biogeographic patterns of atractaspidines with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). We sampled 91 individuals from both atractaspidine genera (Atractaspis and Homoroselaps). Additionally, we used ancestral-state reconstructions to investigate fang and diet evolution within Atractaspidinae and its sister lineage (Aparallactinae). Our results indicated that current classification of atractaspidines underestimates diversity within the group. Diversification occurred predominantly between the Miocene and Pliocene. Ancestral-state reconstructions suggest that snake dentition in these taxa might be highly plastic within relatively short periods of time to facilitate adaptations to dynamic foraging and life-history strategies.


Asunto(s)
Viperidae/clasificación , Viperidae/genética , Estructuras Animales/anatomía & histología , Estructuras Animales/fisiología , Animales , Citocromos b/genética , Evolución Molecular , Genes Mitocondriales , Genes RAG-1 , Genes mos , NADH Deshidrogenasa/genética , Filogenia , Conducta Predatoria , ARN Ribosómico 16S/genética , Factores de Tiempo , Viperidae/fisiología
3.
Nat Commun ; 9(1): 4697, 2018 11 08.
Artículo en Inglés | MEDLINE | ID: mdl-30409973

RESUMEN

Despite extensive research on ecological community compositions, general patterns across large-scale environmental gradients have remained unclear. A widely used explanatory model is the stress dominance hypothesis (SDH), predicting that the relative influence of environmental filtering is greater in stressful habitats while competition is more important in benign environments. Here, we test the SDH using African squamates as a model system to facilitate general predictions on community structures amidst changing global environments. For the first time we investigate changes in functional, phylogenetic and species diversity across continental, environmental gradients within a multidimensional, phylogenetically informed approach. Results suggest that phylogenetic patterns of African squamates were likely shaped by clade-specific biogeographic histories, whereas functional structure reflects SDH predictions. We further detected significant structuring at both local and regional spatial scales, emphasizing the impact of regional-historical processes on local assemblages, and the need for broad conceptual frameworks to detect general patterns of community composition.


Asunto(s)
Biodiversidad , Filogenia , Reptiles/clasificación , África , Animales , Clima , Ecosistema , Carácter Cuantitativo Heredable , Especificidad de la Especie
4.
Sci Total Environ ; 613-614: 1376-1384, 2018 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-29898505

RESUMEN

Global change effects on biodiversity and human wellbeing call for improved long-term environmental data as a basis for science, policy and decision making, including increased interoperability, multifunctionality, and harmonization. Based on the example of two global initiatives, the International Long-Term Ecological Research (ILTER) network and the Group on Earth Observations Biodiversity Observation Network (GEO BON), we propose merging the frameworks behind these initiatives, namely ecosystem integrity and essential biodiversity variables, to serve as an improved guideline for future site-based long-term research and monitoring in terrestrial, freshwater and coastal ecosystems. We derive a list of specific recommendations of what and how to measure at a monitoring site and call for an integration of sites into co-located site networks across individual monitoring initiatives, and centered on ecosystems. This facilitates the generation of linked comprehensive ecosystem monitoring data, supports synergies in the use of costly infrastructures, fosters cross-initiative research and provides a template for collaboration beyond the ILTER and GEO BON communities.


Asunto(s)
Biodiversidad , Ecosistema , Monitoreo del Ambiente/métodos , Política Ambiental , Toma de Decisiones , Monitoreo del Ambiente/estadística & datos numéricos
5.
Mol Phylogenet Evol ; 127: 288-303, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-29551523

RESUMEN

Members of the snake subfamily Aparallactinae occur in various habitats throughout sub-Saharan Africa. The monophyly of aparallactine snakes is well established, but relationships within the subfamily are poorly known. We sampled 158 individuals from six of eight aparallactine genera in sub-Saharan Africa. We employed concatenated gene-tree analyses, divergence dating approaches, and ancestral-area reconstructions to infer phylogenies and biogeographic patterns with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). As a result, we uncover several cryptic lineages and elevate a lineage of Polemon to full species status. Diversification occurred predominantly during the Miocene, with a few speciation events occurring subsequently in the Pliocene and Pleistocene. Biogeographic analyses suggested that the Zambezian biogeographic region, comprising grasslands and woodlands, facilitated radiations, vicariance, and dispersal for many aparallactines. Moreover, the geographic distributions of many forest species were fragmented during xeric and cooler conditions, which likely led to diversification events. Biogeographic patterns of aparallactine snakes are consistent with previous studies of other sub-Saharan herpetofauna.


Asunto(s)
Clima Desértico , Lagartos/anatomía & histología , Lagartos/clasificación , Filogenia , Filogeografía , África del Sur del Sahara , Animales , ADN Mitocondrial/genética , Funciones de Verosimilitud , Lagartos/genética , Serpientes/anatomía & histología , Serpientes/genética
6.
Mol Phylogenet Evol ; 120: 274-285, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29246817

RESUMEN

Frogs in the genus Amnirana (family Ranidae) are widely distributed across sub-Saharan Africa and present a model system for exploring the relationship between diversification and geography across the continent. Using multiple loci from the mitochondrial (16S) and nuclear genomes (DISP2, FICD, KIAA2013, REV3L), we generated a strongly supported species-level phylogeny that provides insights into the continental biogeography of African species of Amnirana, which form a monophyletic group within the genus. Species delimitation analyses suggest that there may be as many as seven additional species of Amnirana in Africa. The biogeographic history of Amnirana is marked by several dispersal and vicariance events, including dispersal from the Lower Guinean Forest into the Congo Basin. In addition, phylogeographic patterns within two widespread species, A. albolabris and A. galamensis, reveal undescribed cryptic diversity. Populations assigned to A. albolabris in western Africa are more closely related to A. fonensis and require recognition as a distinct species. Our analyses reveal that the Lower and Upper Guinean Forest regions served as important centers of interspecific and intraspecific diversifications for Amnirana.


Asunto(s)
Anuros/clasificación , Biodiversidad , Filogenia , África del Sur del Sahara , Proteínas Anfibias/clasificación , Proteínas Anfibias/genética , Proteínas Anfibias/metabolismo , Animales , Anuros/genética , ADN/clasificación , ADN/aislamiento & purificación , ADN/metabolismo , ADN Mitocondrial/clasificación , ADN Mitocondrial/aislamiento & purificación , ADN Mitocondrial/metabolismo , Evolución Molecular , Proteínas de la Membrana/clasificación , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Filogeografía , Análisis de Secuencia de ADN
7.
Proc Biol Sci ; 284(1851)2017 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-28356450

RESUMEN

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial modes of reproduction are strongly correlated with steep terrain and low availability of accumulated water sources. Evolutionary transitions to terrestrial modes of reproduction occurred synchronously with or after transitions in habitat, and we, therefore, interpret terrestrial breeding as an adaptation to these abiotic conditions, rather than an exaptation that facilitated the colonization of montane habitats.


Asunto(s)
Bufonidae/fisiología , Ambiente , Reproducción , Animales , Evolución Biológica , Filogenia
8.
Mol Phylogenet Evol ; 106: 254-269, 2017 01.
Artículo en Inglés | MEDLINE | ID: mdl-27664344

RESUMEN

The Mascarene ridged frog, Ptychadena mascareniensis, is a species complex that includes numerous lineages occurring mostly in humid savannas and open forests of mainland Africa, Madagascar, the Seychelles, and the Mascarene Islands. Sampling across this broad distribution presents an opportunity to examine the genetic differentiation within this complex and to investigate how the evolution of bioclimatic niches may have shaped current biogeographic patterns. Using model-based phylogenetic methods and molecular-clock dating, we constructed a time-calibrated molecular phylogenetic hypothesis for the group based on mitochondrial 16S rRNA and cytochrome b (cytb) genes and the nuclear RAG1 gene from 173 individuals. Haplotype networks were reconstructed and species boundaries were investigated using three species-delimitation approaches: Bayesian generalized mixed Yule-coalescent model (bGMYC), the Poisson Tree Process model (PTP) and a cluster algorithm (SpeciesIdentifier). Estimates of similarity in bioclimatic niche were calculated from species-distribution models (maxent) and multivariate statistics (Principal Component Analysis, Discriminant Function Analysis). Ancestral-area reconstructions were performed on the phylogeny using probabilistic approaches implemented in BioGeoBEARS. We detected high levels of genetic differentiation yielding ten distinct lineages or operational taxonomic units, and Central Africa was found to be a diversity hotspot for these frogs. Most speciation events took place throughout the Miocene, including "out-of-Africa" overseas dispersal events to Madagascar in the East and to São Tomé in the West. Bioclimatic niche was remarkably well conserved, with most species tolerating similar temperature and rainfall conditions common to the Central African region. The P. mascareniensis complex provides insights into how bioclimatic niche shaped the current biogeographic patterns with niche conservatism being exhibited by the Central African radiation and niche divergence shaping populations in West Africa and Madagascar. Central Africa, including the Albertine Rift region, has been an important center of diversification for this species complex.


Asunto(s)
Ranidae/clasificación , África , Animales , Teorema de Bayes , Citocromos b/clasificación , Citocromos b/genética , Citocromos b/metabolismo , ADN/química , ADN/aislamiento & purificación , ADN/metabolismo , Ecología , Haplotipos , Proteínas de Homeodominio/clasificación , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Madagascar , Filogenia , Filogeografía , Análisis de Componente Principal , ARN Ribosómico 16S/clasificación , ARN Ribosómico 16S/genética , ARN Ribosómico 16S/metabolismo , Ranidae/genética , Análisis de Secuencia de ADN
9.
Zootaxa ; 4032(1): 55-80, 2015 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-26624339

RESUMEN

We describe two new species of puddle frogs, genus Phrynobatrachus, from the south-western Republic of the Congo. One of them, P. horsti sp. nov., occurs also in neighbouring Gabon and is morphologically most similar to the Cameroonian P. ruthbeateae. It differs from the latter species by smaller males with longer thighs and shanks. The new species comprises various colour morphs but always has less conspicuous black borders between flanks and belly than P. ruthbeateae. The distinct and large black axillary blotch of P. ruthbeateae is either much smaller in P. horsti sp. nov., or broken into numerous irregularly shaped smaller dots. Similarly, a black transversal line at the anterior ventral border of thighs and the black face mask is less distinct and irregularly delimitated in P. horsti sp. nov. when compared to P. ruthbeateae. The mean genetic difference in the sampled region of the 16S rRNA gene between P. horsti sp. nov. and 40 other western African congeners range from 3.66-18.10%. The second new species, P. mayokoensis sp. nov., differs from all other known congeners by the combination of a compact and warty body, the absence of a spiny eyelid tubercle and pedal webbing, a conspicuous black triangle on throat and anterior part of the belly, and a distinct large red blotch on the anterior-proximal surface of the thighs. It exhibited a mean genetic difference in the 16S rRNA to 40 other western African congeners ranging from 1.34-16.98%. The genetically most similar sequence stems from a GenBank entry of a Gabonese frog, determined as P. ogoensis. A comparison of the new species with P. ogoensis syntypes confirmed their specific distinctiveness, most convincingly underlined by the absence of pedal webbing in the new species and the pronounced pedal webbing in P. ogoensis. The GenBank entry thus most likely is based on a misidentification and P. mayokoensis sp. nov. may also occur in neighbouring Gabon. The discovery of the two new frog species is further evidence of the huge gap in our knowledge concerning the species richness in the Guineo-Congolian rainforests.


Asunto(s)
Anuros/clasificación , Distribución Animal , Estructuras Animales/anatomía & histología , Estructuras Animales/crecimiento & desarrollo , Animales , Anuros/anatomía & histología , Anuros/crecimiento & desarrollo , Tamaño Corporal , Congo , Ecosistema , Femenino , Masculino , Tamaño de los Órganos
10.
BMC Evol Biol ; 15: 67, 2015 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-25928080

RESUMEN

BACKGROUND: Correct species identification is crucial in different fields of biology, and in conservation. The endemic West African frog family Odontobatrachidae currently contains a single described species, Odontobatrachus natator. From western Guinea to western Côte d'Ivoire it inhabits forests around waterfalls or cascades. Based on more than 130 specimens from 78 localities, covering the entire distribution, we investigated the molecular diversity of these frogs. RESULTS: Our analyses included mitochondrial and nuclear genes, with a concatenated alignment of 3527 base pairs. We detected high level of genetic differentiation with five distinct lineages or operational taxonomic units (OTUs). These OTUs were also identified by two different species delimitation approaches, Generalized Mixed Yule Coalescent (GMYC) and cluster algorithm. All OTUs occur in parapatry in the Upper Guinean forests. One OTU, assigned to the "true" Odontobatrachus natator, covers the largest distribution, ranging from the border region of western Sierra Leone-Guinea to eastern Liberia. Two OTUs are restricted to western Guinea (Fouta Djallon and foothills), while two others occur in eastern Guinea and the border region of Guinea-Liberia-Côte d'Ivoire. The OTU representing O. natator consists of two divergent subclades: one restricted to the Freetown Peninsula (Sierra Leone) and the other covering all populations further inland. Environmental niche models indicated that the restricted Freetown Peninsula population is separated by unsuitable habitat from remaining populations. CONCLUSION: Geographic isolation of OTUs and molecular differences comparable to species level differentiation in other frog families indicate that O. natator contains cryptic species diversity. Respective distribution patterns most probably resulted from repeated changes of forest cover (contraction and expansion) over evolutionary timescales. The survival within forest refugia that have persisted through multiple drier periods and subsequent dispersal during wetter times may best explain the observed geographic distributions of OTUs. According to the IUCN Red List range criteria each OTU should be classified as "Endangered." If the Freetown Peninsula "natator" population is recognized as a distinct species it would warrant recognition as "Critically Endangered." The identification of cryptic lineages highlights the urgent need to protect these frogs, all of which are endemic to small areas within the Upper Guinean biodiversity hotspot.


Asunto(s)
Anuros/clasificación , Anuros/genética , África Occidental , Animales , Biodiversidad , Ecosistema , Especies en Peligro de Extinción , Filogenia
11.
Mol Phylogenet Evol ; 71: 261-73, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24239613

RESUMEN

Torrent frogs of the genus Petropedetes Reichenow, 1874 as currently understood have a disjunct distribution with species endemic to West, Central or East Africa. We herein present a phylogenetic analysis including all but one of the currently described 12 species of the genus. Maximum Likelihood and Bayesian analyses of combined nuclear (rag1, SIA, BDNF) and mitochondrial (16S, 12S, cytb) genes of more than 3500 base pairs, revealed clades corresponding to the three sub-Saharan regions. Molecular results are confirmed by morphological differences. Surprisingly, the three geographic clades do not form a monophyletic group with respect to closely related families Pyxicephalidae and Conrauidae and therefore require taxonomic changes. We resurrect Arthroleptides Nieden, 1911 for the East African taxa. The Central African taxa remain in the genus Petropedetes. The West African members are placed in the new genus Odontobatrachus gen. nov. The taxonomic position of the new genus remains incertae sedis as it was not assigned to any of the four families included in our analyses. Potential new species have been detected within all three major clades, pointing to a still not fully clarified diversity within African torrent frogs.


Asunto(s)
Anuros/genética , Filogenia , África , Animales , Anuros/clasificación , Teorema de Bayes , ADN Mitocondrial/genética , Evolución Molecular , Funciones de Verosimilitud , Filogeografía , Análisis de Secuencia de ADN
12.
PLoS One ; 8(2): e56236, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23426141

RESUMEN

A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni ("Vulnerable") and Petropedetes natator ("Near Threatened")) as well as the "Critically Endangered" viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis).


Asunto(s)
Anuros/microbiología , Quitridiomicetos/genética , Dermatomicosis/epidemiología , Dermatomicosis/veterinaria , África Occidental/epidemiología , Animales , Ecosistema , Modelos Biológicos , Reacción en Cadena de la Polimerasa , Especificidad de la Especie
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA