10 research outputs found
Rapid ecological specialization despite constant population sizes
Background
The bushbuck, Tragelaphus scriptus, is a widespread and ecologically diverse ungulate species complex within the spiral-horned antelopes. This species was recently found to consist of two genetically divergent but monophyletic lineages, which are paraphyletic at mitochondrial (mt)DNA owing to an ancient interspecific hybridization event. The Scriptus lineage (T. s. scriptus) inhabits the north-western half of the African continent while Sylvaticus (T. s. sylvaticus) is found in the south-eastern half. Here we test hypotheses of historical demography and adaptation in bushbuck using a higher-resolution framework, with four nuclear (MGF, PRKCI, SPTBN, and THY) and three new mitochondrial markers (cytochrome b, 12S rRNA, and 16S rRNA).
Methods
Genealogies were reconstructed for the mitochondrial and nuclear data sets, with the latter dated using fossil calibration points. We also inferred the demographic history of Scriptus and Sylvaticus using coalescent-based methods. To obtain an overview of the origins and ancestral colonisation routes of ancestral bushbuck sequences across geographic space, we conducted discrete Bayesian phylogeographic and statistical dispersal-vicariance analyses on our nuclear DNA data set.
Results
Both nuclear DNA and mtDNA support previous findings of two genetically divergent Sylvaticus and Scriptus lineages. The three mtDNA loci confirmed 15 of the previously defined haplogroups, including those with convergent phenotypes. However, the nuclear tree showed less phylogenetic resolution at the more derived parts of the genealogy, possibly due to incomplete lineage sorting of the slower evolving nuclear genome. The only exception to this was the montane Menelikâs bushbuck (Sylvaticus) of the Ethiopian highlands, which formed a monophyletic group at three of four nuclear DNA loci. We dated the coalescence of the two lineages to a common ancestor âŒ2.54 million years ago. Both marker sets revealed similar demographic histories of constant population size over time. We show that the bushbuck likely originated in East Africa, with Scriptus dispersing to colonise suitable habitats west of the African Rift and Sylvaticus radiating from east of the Rift into southern Africa via a series of mainly vicariance events.
Discussion
Despite lower levels of genetic structure at nuclear loci, we confirmed the independent evolution of the Menelikâs bushbuck relative to the phenotypically similar montane bushbuck in East Africa, adding further weight to previous suggestions of convergent evolution within the bushbuck complex. Perhaps the most surprising result of our analysis was that both Scriptus and Sylvaticus populations remained relatively constant throughout the Pleistocene, which is remarkable given that this was a period of major climatic and tectonic change in Africa, and responsible for driving the evolution of much of the continentâs extant large mammalian diversity
Lois et rĂšglements sur la faune sauvage Ă Madagascar : ProgrĂšs accomplis et besoins du futur
In many countries wildlife species are threatened by hunting for meat or collection for the pet trade. Wildlife laws which control where these activities can occur, limit the timing of exploitation, or provide strict protection for some species are therefore an important component of the conservation strategy. However it is important that these wildlife laws reflect the ecology and threat status of the species concerned, and that they are aligned with any relevant international conventions. In this article we discuss the legal framework for exploiting and protecting tetrapod species in Madagascar. We review the 2006 update to wildlife legislation with respect to international treaties, other national legislation and the IUCN Red List of Threatened Species. We also present a summary of the different categories of hunting (sport, commercial, scientific, and subsistence) and the control of hunting in protected areas. Madagascar has a sound legal framework for the use and protection of wildlife and the classification of species into protected, pest and legally hunted is clear and mostly fits well with the speciesâ classification according to the IUCN Red List and CITES. A revision of the protected species list managed is needed however to (i) include marine mammals that are protected by fisheries law and the Convention on Migratory Species and to (ii) better reflect the rights of people whose livelihoods rely heavily on the income or protein derived from hunting animals. Renewed effort to communicate and enforce wildlife legislation is needed, especially regarding the illegal hunting and export of protected species. This would also support the ongoing initiative to expand the protected area system and could be integrated into a revised National Biodiversity Strategy and Action Plan that Madagascar should produce for 2011-2020 as part of its commitment to implementing the Convention on Biological Diversity. RĂSUMĂLes lois et rĂšglements dĂ©terminant les niveaux de protection des espĂšces de la faune et de la flore sauvages sont des indicateurs importants de lâimportance quâaccorde un pays Ă la conservation de sa biodiversitĂ©. Dans cette revue, nous Ă©valuons la cohĂ©rence entre les lois et rĂšglements portant sur la gestion de la faune sauvage Ă Madagascar, en considĂ©rant la lĂ©gislation nationale, les conventions internationales ratifiĂ©es et la Liste Rouge de lâUICN pour les confronter aux rĂ©alitĂ©s locales. Suite Ă nos analyses, nous pouvons conclure que Madagascar dispose dâun cadre juridique adĂ©quat pour rĂ©glementer la protection et lâexploitation des animaux sauvages. Cependant, des rĂ©visions et mises Ă jour sont nĂ©cessaires, particuliĂšrement en ce qui concerne la liste des espĂšces dans les diffĂ©rentes catĂ©gories et la facilitation de la mise en application de la loi
Phylogeography and population genetics of the endemic Malagasy bat, Macronycteris commersoni s.s. (Chiroptera: Hipposideridae)
Macronycteris commersoni (Hipposideridae), a bat species endemic to Madagascar, is widespread across the island and utilizes a range of habitat types including open woodland, degraded habitats, and forested areas from sea level to 1,325 m. Despite being widely distributed, there is evidence that M. commersoni exhibits morphological and bioacoustic variation across its geographical range. We investigated the fine-scale phylogeographic structure of populations in the western half of the island using extensive spatial sampling and sequence data from two mitochondrial DNA regions. Our results indicated several lineages within M. commersoni. Individuals collected from northern Madagascar formed a single monophyletic clade (clade C). A second clade (clade B) included individuals collected from the south-western portion of the island. This second clade displayed more phylogeographical partitioning with differences in mtDNA haplotypes frequency detected between populations collected in different bioclimatic regions. Lineage dispersal, genetic divergence, and timing of expansion events of M. commersoni were probably associated with Pleistocene climate fluctuations. Our data suggest that the northern and the central western regions of Madagascar may have acted as refugia for this species during periods of cooler and drier climate conditions associated with the Pleistocene
A conservation assessment of Rousettus madagascariensis (Grandidier, 1929, Pteropodidae) roosts in eastern Madagascar
We visited four cave roosts of the near threatened, and endemic, fruit bat Rousettus madagascariensis over a five year period and found major threats to the bats from hunting and deforestation. The conservation of this species is particularly challenging because it is legally hunted inside its cave roosts. Although provisional protected area status was obtained for two sites with community support, hunting continued. R. madagascariensis roosts were associated with humid forest and the loss of vegetation around caves rendered them unsuitable for the bats at two abandoned sites. A few individual hunters can have a rapid and destructive impact on R. madagascariensis roosts and future initiatives in this area should involve working with hunters to develop realistic solutions to reduce hunting. These efforts need to be supported by habitat protection measures. RĂSUMĂ LâespĂšce de chauve-souris frugivore Quasi MenacĂ©e Rousettus madagascariensis est endĂ©mique Ă Madagascar. Nous avons Ă©tudiĂ© quatre gĂźtes dans des grottes oĂč cette espĂšce a Ă©tabli des dortoirs diurnes en procĂ©dant Ă des visites multiples au cours dâune pĂ©riode de cinq ans et avons trouvĂ© que la chasse et la dĂ©forestation constituaient les principales menaces pesant sur R. madagascariensis. La conservation de cette espĂšce est particuliĂšrement difficile dans la mesure oĂč la chasse dans ses dortoirs ou gĂźtes est permise. Bien que les deux sites abritant lâespĂšce bĂ©nĂ©ficient du statut de Nouvelle Aire ProtĂ©gĂ©e avec le soutien de la communautĂ© locale, la chasse ne cesse de sâintensifier. Les gĂźtes de R. madagascariensis sont associĂ©s Ă la forĂȘt humide, de sorte que la disparition de la vĂ©gĂ©tation arborĂ©e autour de deux de ces gĂźtes les a rendus impropres Ă hĂ©berger R. madagascariensis qui a fini par les abandonner. La disparition de la vĂ©gĂ©tation arborĂ©e autour du gĂźte pourrait ĂȘtre Ă lâorigine dâun changement de microclimat Ă lâintĂ©rieur de la grotte qui constitue le gĂźte diurne. Les activitĂ©s de certains chasseurs peuvent aussi avoir un impact destructif rapide sur les gĂźtes de R. madagascariensis et des initiatives Ă mener conjointement avec les chasseurs sont nĂ©cessaires pour Ă©laborer des mesures rĂ©alistes afin de rĂ©duire la chasse. De tels efforts doivent ĂȘtre Ă©tendus et appuyĂ©s par des mesures de protection de l'habitat car plusieurs autres gĂźtes pourraient exister dans les forĂȘts du versant est de Madagascar et subir les mĂȘmes pressions anthropiques. Des recherches rĂ©centes ont Ă©galement montrĂ© que lâhistoire naturelle de R. madagascariensis est Ă©troitement liĂ©e Ă la forĂȘt naturelle, de sorte que la perte de la biodiversitĂ© de la forĂȘt naturelle malgache menace les plantes dont se nourrit cette espĂšce ainsi que lâĂ©quilibre de lâensemble de lâĂ©cosystĂšme dont elle dĂ©pend.
Analysis of patterns of bushmeat consumption reveals extensive exploitation of protected species in eastern Madagascar.
Understanding the patterns of wild meat consumption from tropical forests is important for designing approaches to address this major threat to biodiversity and mitigate potential pathways for transmission of emerging diseases. Bushmeat consumption has been particularly poorly studied in Madagascar, one of the worldâs hottest biodiversity hotspots. Studying bushmeat consumption is challenging as many species are protected and researchers must consider the incentives faced by informants. Using interviews with 1154 households in 12 communes in eastern Madagascar, as well as local monitoring data, we investigated the importance of socio-economic variables, taste preference and traditional taboos on consumption of 50 wild and domestic species. The majority of meals contain no animal protein. However, respondents consume a wide range of wild species and 95% of respondents have eaten at least one protected species (and nearly 45% have eaten more than 10). The rural/urban divide and wealth are important predictors of bushmeat consumption, but the magnitude and direction of the effect varies between species. Bushmeat species are not preferred and are considered inferior to fish and domestic animals. Taboos have provided protection to some species, particularly the Endangered Indri, but we present evidence that this taboo is rapidly eroding. By considering a variety of potential influences on consumption in a single study we have improved understanding of who is eating bushmeat and why. Evidence that bushmeat species are not generally preferred meats suggest that projects which increase the availability of domestic meat and fish may have success at reducing demand. We also suggest that enforcement of existing wildlife and firearm laws should be a priority, particularly in areas undergoing rapid social change. The issue of hunting as an important threat to biodiversity in Madagascar is only now being fully recognised. Urgent action is required to ensure that heavily hunted species are adequately protected
Southern Africa's great escarpment as an amphitheater of climate-driven diversification and a buffer against future climate change in bats
DATA AVAILABILITY STATEMENT :
Raw cyt-b sequence data (FASTA files; Datasets S1âS3) and craniometric and specimen data (Excel files; Datasets S4âS7) are openly available on Dryad at https://doi.org/10.5061/dryad.3bk3j9ksc.Hosting 1460 plant and 126 vertebrate endemic species, the Great Escarpment (hereafter, Escarpment) forms a semi-circular âamphitheaterâ of mountains girdling southern Africa from arid west to temperate east. Since arid and temperate biota are usually studied separately, earlier studies overlooked the biogeographical importance of the Escarpment as a whole. Bats disperse more widely than other mammalian taxa, with related species and intraspecific lineages occupying both arid and temperate highlands of the Escarpment, providing an excellent model to address this knowledge gap. We investigated patterns of speciation and micro-endemism from modeled past, present, and future distributions in six clades of southern African bats from three families (Rhinolophidae, Cistugidae, and Vespertilionidae) having different crown ages (Pleistocene to Miocene) and biome affiliations (temperate to arid). We estimated mtDNA relaxed clock dates of key divergence events across the six clades in relation both to biogeographical features and patterns of phenotypic variation in crania, bacula and echolocation calls. In horseshoe bats (Rhinolophidae), both the western and eastern âarmsâ of the Escarpment have facilitated dispersals from the Afrotropics into southern Africa. Pleistocene and pre-Pleistocene âspecies pumpsâ and temperate refugia explained observed patterns of speciation, intraspecific divergence and, in two cases, mtDNA introgression. The Maloti-Drakensberg is a center of micro-endemism for bats, housing three newly described or undescribed species. Vicariance across biogeographic barriers gave rise to 29 micro-endemic species and intraspecific lineages whose distributions were congruent with those identified in other phytogeographic and zoogeographic studies. Although KöppenâGeiger climate models predict a widespread replacement of current temperate ecosystems in southern Africa by tropical or arid ecosystems by 2070â2100, future climate Maxent models for 13 bat species (all but one of those analyzed above) showed minimal range changes in temperate species from the eastern Escarpment by 2070, possibly due to the buffering effect of mountains to climate change.National Research Foundation and
Department of Science and Innovation
of South Africa; Afromontane Research Unit,
University of the Free State; National
Research Foundation.http://www.wileyonlinelibrary.com/journal/gcbhj2024Medical VirologySDG-15:Life on lan