From genetic diversity and structure to conservation: Genetic signature of recent population declines in three mouse lemur species (Microcebus spp.) / Gillian L. Olivieri  

Public ISBD Titre : From genetic diversity and structure to conservation: Genetic signature of recent population declines in three mouse lemur species (Microcebus spp.) Type de document : texte imprimé Auteurs : Gillian L. Olivieri ; Vitor Sousa ; Lounès Chikhi ; Ute Radespiel Année de publication : 2008 Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Génétique, Parasite, Maladie Mots-clés : POPULATION STRUCTURE  DEMOGRAPHIC HISTORY  HABITAT FRAGMENTATION  MICROSATELLITES  CONSERVATION  MADAGASCAR Résumé : The exceptional biodiversity of Madagascar is threatened by anthropogenic landscape changes that took place during the 2000 years of human colonization. This study focuses on the influence of geographic distance and forest fragmentation on genetic diversity and population differentiation of three rare, nocturnal, arboreal lemur species in northwestern Madagascar. Historic declines in population sizes as a consequence of forest fragmentation are quantified and dated. Eighteen sites were visited, and a total of 205 Microcebus ravelobensis, 45 M. bongolavensis and 78 M. danfossi were genotyped with eight microsatellite loci. Genetic differentiation among the sites, as measured by FST, ranged from 0.01 to 0.19. These values were significant in almost all cases and indicated genetic structure in the samples. Isolation-by-distance was detected in one species and a STRUCTURE analysis indicated that fragmentation further promoted genetic differentiation. Bayesian methods revealed that populations from all three species underwent a major demographic collapse of around two orders of magnitude. This decrease probably began after the arrival of humans, most likely within the last 500 years. This result suggests that anthropogenic changes may have been limited during the first 1500 years of human colonization in all three ranges. Two of the study species (M. danfossi, M. bongolavensis) lack effectively protected areas in their ranges. Consequently, quick conservation actions are now needed in order to secure the remaining genetic diversity of these species. Titre du périodique : Biological Conservation Volume : 141 (5): 1257-1271 En ligne : https://doi.org/10.1016/j.biocon.2008.02.025 From genetic diversity and structure to conservation: Genetic signature of recent population declines in three mouse lemur species (Microcebus spp.) [texte imprimé] / Gillian L. Olivieri ; Vitor Sousa ; Lounès Chikhi ; Ute Radespiel . - 2008. Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Génétique, Parasite, Maladie Mots-clés : POPULATION STRUCTURE  DEMOGRAPHIC HISTORY  HABITAT FRAGMENTATION  MICROSATELLITES  CONSERVATION  MADAGASCAR Résumé : The exceptional biodiversity of Madagascar is threatened by anthropogenic landscape changes that took place during the 2000 years of human colonization. This study focuses on the influence of geographic distance and forest fragmentation on genetic diversity and population differentiation of three rare, nocturnal, arboreal lemur species in northwestern Madagascar. Historic declines in population sizes as a consequence of forest fragmentation are quantified and dated. Eighteen sites were visited, and a total of 205 Microcebus ravelobensis, 45 M. bongolavensis and 78 M. danfossi were genotyped with eight microsatellite loci. Genetic differentiation among the sites, as measured by FST, ranged from 0.01 to 0.19. These values were significant in almost all cases and indicated genetic structure in the samples. Isolation-by-distance was detected in one species and a STRUCTURE analysis indicated that fragmentation further promoted genetic differentiation. Bayesian methods revealed that populations from all three species underwent a major demographic collapse of around two orders of magnitude. This decrease probably began after the arrival of humans, most likely within the last 500 years. This result suggests that anthropogenic changes may have been limited during the first 1500 years of human colonization in all three ranges. Two of the study species (M. danfossi, M. bongolavensis) lack effectively protected areas in their ranges. Consequently, quick conservation actions are now needed in order to secure the remaining genetic diversity of these species. Titre du périodique : Biological Conservation Volume : 141 (5): 1257-1271 En ligne : https://doi.org/10.1016/j.biocon.2008.02.025

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Influence of forest fragmentation on an endangered large-bodied lemur in northwestern Madagascar / Mathias Craul  

Public ISBD Titre : Influence of forest fragmentation on an endangered large-bodied lemur in northwestern Madagascar Type de document : texte imprimé Auteurs : Mathias Craul, Auteur ; Lounès Chikhi, Auteur ; Vitor Sousa, Auteur ; Gillian L. Olivieri ; Andriatahiana Rabesandratana, Auteur ; Elke Zimmermann, Auteur ; Ute Radespiel, Auteur Année de publication : 2009 Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Fragmentation, Habitat Mots-clés : LEPILEMUR EDWARDSI  POPULATION GENETICS  D-LOOP, MICROSATELLITES  GENETIC DIVERSITY  BOTTLENECK Résumé : Madagascar’s diverse and mostly endemic fauna and flora suffer from recent landscape changes that are primarily caused by high levels of human activities. The loss and fragmentation of forest habitats are well known consequences of human activities. In this study, we investigate the effects of forest fragmentation on presence, abundance and genetic diversity in a larger-bodied lemur species, Lepilemur edwardsi, in northwestern Madagascar. In addition, we characterized the genetic differentiation among populations and demographic changes. We found L. edwardsi at only 13 (76.5%) of 17 visited sites, 11 of which were situated in the Ankarafantsika National Park (ANP). We captured between two and 17 individuals per site. We sequenced the mtDNA d-loop of all samples and genotyped 14 microsatellite loci in two exemplary populations for demographic analyses. A negative influence on forest fragmentation could be detected, since the fragments had a lower genetic diversity than sites in the ANP. Genetic differentiation between populations ranged from low to high but was almost always significant. A typical pattern of isolation-by-distance could not be detected and the data could rather be interpreted as results of random genetic drift. The data furthermore revealed signals of a demographic collapse of about two orders of magnitude in the two exemplary sites. This decline probably started during the last few hundred years of intensified human disturbances and population growth. Given the results of this study, urgent conservation actions are needed and should concentrate on an effective protection of the few remaining populations in order to ensure the long-term survival of L. edwardsi. Titre du périodique : Biological Conservation Volume : 142 (12) : 2862-2871 En ligne : https://doi.org/10.1016/j.biocon.2009.05.026 Influence of forest fragmentation on an endangered large-bodied lemur in northwestern Madagascar [texte imprimé] / Mathias Craul, Auteur ; Lounès Chikhi, Auteur ; Vitor Sousa, Auteur ; Gillian L. Olivieri ; Andriatahiana Rabesandratana, Auteur ; Elke Zimmermann, Auteur ; Ute Radespiel, Auteur . - 2009. Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Fragmentation, Habitat Mots-clés : LEPILEMUR EDWARDSI  POPULATION GENETICS  D-LOOP, MICROSATELLITES  GENETIC DIVERSITY  BOTTLENECK Résumé : Madagascar’s diverse and mostly endemic fauna and flora suffer from recent landscape changes that are primarily caused by high levels of human activities. The loss and fragmentation of forest habitats are well known consequences of human activities. In this study, we investigate the effects of forest fragmentation on presence, abundance and genetic diversity in a larger-bodied lemur species, Lepilemur edwardsi, in northwestern Madagascar. In addition, we characterized the genetic differentiation among populations and demographic changes. We found L. edwardsi at only 13 (76.5%) of 17 visited sites, 11 of which were situated in the Ankarafantsika National Park (ANP). We captured between two and 17 individuals per site. We sequenced the mtDNA d-loop of all samples and genotyped 14 microsatellite loci in two exemplary populations for demographic analyses. A negative influence on forest fragmentation could be detected, since the fragments had a lower genetic diversity than sites in the ANP. Genetic differentiation between populations ranged from low to high but was almost always significant. A typical pattern of isolation-by-distance could not be detected and the data could rather be interpreted as results of random genetic drift. The data furthermore revealed signals of a demographic collapse of about two orders of magnitude in the two exemplary sites. This decline probably started during the last few hundred years of intensified human disturbances and population growth. Given the results of this study, urgent conservation actions are needed and should concentrate on an effective protection of the few remaining populations in order to ensure the long-term survival of L. edwardsi. Titre du périodique : Biological Conservation Volume : 142 (12) : 2862-2871 En ligne : https://doi.org/10.1016/j.biocon.2009.05.026

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Lemurs in a dying forest: Factors influencing lemur diversity and distribution in forest remnants of north-eastern Madagascar / Dominik Schüßler  

Public ISBD Titre : Lemurs in a dying forest: Factors influencing lemur diversity and distribution in forest remnants of north-eastern Madagascar Type de document : texte imprimé Auteurs : Dominik Schüßler, Auteur ; Ute Radespiel, Auteur ; Ratsimbazafy, Auteur ; Jasmin Mantilla-Contreras, Auteur Année de publication : 2018 Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Fragmentation, Habitat Mots-clés : DEFORESTATION  FOREST FRAGMENTATION  HABITAT DEGRADATION  COMMUNITY-BASED  FOREST MANAGEMENT  CONSERVATION Résumé : A majority of Madagascar's iconic lemurs (Primates, Strepsirrhini) is threatened with extinction due to anthropogenic activities like land use change (deforestation) and bushmeat hunting. We used a multivariate approach combining land cover mapping, vegetation/degradation monitoring, the degree of anthropogenic disturbance and the status of forest protection by the local community to model their impact on lemur diversity, population densities and encounter rates within a rural area of lowland rain forest in north-eastern Madagascar. High mean annual deforestation rates (2.4%) were calculated since 1990, resulting in a landscape of small and isolated forest fragments. A limited number of eight lemur species belonging to five lemur families were encountered. Diurnal species were absent, while cathemeral lemurs avoided human disturbance. Small and nocturnal species were relatively abundant. Overall lemur diversity was best explained by forest size and a combination of disturbance and hunting. Encounter rates of three nocturnal taxa were influenced by forest size and habitat degradation. Community-level forest protection had no effect on lemur diversity, but coincided with lower levels of habitat degradation. Lemur population sizes were relatively small and only few forests remain that offer suitable habitats for viable populations. We highly recommend external conservation NGOs to support local forest management by improving the existing community-based approach. Actions should include expansion of protected habitats to increase population connectivity (reforestation) and to decrease lemur disturbance by villagers. Without external support, the last remaining forest habitats will be devastated within a few years resulting in the local extinction of most lemur populations. Titre du périodique : Biological Conservation Volume : 228: 17-26 En ligne : https://doi.org/10.1016/j.biocon.2018.10.008 Lemurs in a dying forest: Factors influencing lemur diversity and distribution in forest remnants of north-eastern Madagascar [texte imprimé] / Dominik Schüßler, Auteur ; Ute Radespiel, Auteur ; Ratsimbazafy, Auteur ; Jasmin Mantilla-Contreras, Auteur . - 2018. Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Fragmentation, Habitat Mots-clés : DEFORESTATION  FOREST FRAGMENTATION  HABITAT DEGRADATION  COMMUNITY-BASED  FOREST MANAGEMENT  CONSERVATION Résumé : A majority of Madagascar's iconic lemurs (Primates, Strepsirrhini) is threatened with extinction due to anthropogenic activities like land use change (deforestation) and bushmeat hunting. We used a multivariate approach combining land cover mapping, vegetation/degradation monitoring, the degree of anthropogenic disturbance and the status of forest protection by the local community to model their impact on lemur diversity, population densities and encounter rates within a rural area of lowland rain forest in north-eastern Madagascar. High mean annual deforestation rates (2.4%) were calculated since 1990, resulting in a landscape of small and isolated forest fragments. A limited number of eight lemur species belonging to five lemur families were encountered. Diurnal species were absent, while cathemeral lemurs avoided human disturbance. Small and nocturnal species were relatively abundant. Overall lemur diversity was best explained by forest size and a combination of disturbance and hunting. Encounter rates of three nocturnal taxa were influenced by forest size and habitat degradation. Community-level forest protection had no effect on lemur diversity, but coincided with lower levels of habitat degradation. Lemur population sizes were relatively small and only few forests remain that offer suitable habitats for viable populations. We highly recommend external conservation NGOs to support local forest management by improving the existing community-based approach. Actions should include expansion of protected habitats to increase population connectivity (reforestation) and to decrease lemur disturbance by villagers. Without external support, the last remaining forest habitats will be devastated within a few years resulting in the local extinction of most lemur populations. Titre du périodique : Biological Conservation Volume : 228: 17-26 En ligne : https://doi.org/10.1016/j.biocon.2018.10.008

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