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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Past environmental changes affected lemur population dynamics prior to human impact in Madagascar / Helena Teixeira  

Public ISBD Titre : Past environmental changes affected lemur population dynamics prior to human impact in Madagascar Type de document : texte imprimé Auteurs : Helena Teixeira ; Vincent Montade ; Jordi Salmona ; Julia Metzger ; Laurent Bremond ; Thomas Kasper ; Gerhard Daut ; Sylvie Rouland ; Sandratrinirainy Ranarilalatiana ; Lounès Chikhi ; Hermann Behling ; Rakotondravony, Romule- Radespiel, Ute Année de publication : 2021 Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Menaces et Pressions Mots-clés : MICROCEBUS ARNHOLDI  ENVRIONMENTAL CHANGE  MADAGASCAR  ANTROPOGENIC IMPACT Résumé : Quaternary climatic changes have been invoked as important drivers of species diversification worldwide. However, the impact of such changes on vegetation and animal population dynamics in tropical regions remains debated. To overcome this uncertainty, we integrated high-resolution paleoenvironmental reconstructions from a sedimentary record covering the past 25,000 years with demographic inferences of a forest-dwelling primate species (Microcebus arnholdi), in northern Madagascar. Result comparisons suggest that climate changes through the African Humid Period (15.2 – 5.5 kyr) strongly affected the demographic dynamics of M. arnholdi. We further inferred a population decline in the last millennium which was likely shaped by the combination of climatic and anthropogenic impacts. Our findings demonstrate that population fluctuations in Malagasy wildlife were substantial prior to a significant human impact. This provides a critical knowledge of climatically driven, environmental and ecological changes in the past, which is essential to better understand the dynamics and resilience of current biodiversity. Titre du périodique : Communications Biology Volume : 4 : 1084 En ligne : https://doi.org/10.1038/s42003-021-02620-1 Past environmental changes affected lemur population dynamics prior to human impact in Madagascar [texte imprimé] / Helena Teixeira ; Vincent Montade ; Jordi Salmona ; Julia Metzger ; Laurent Bremond ; Thomas Kasper ; Gerhard Daut ; Sylvie Rouland ; Sandratrinirainy Ranarilalatiana ; Lounès Chikhi ; Hermann Behling ; Rakotondravony, Romule- Radespiel, Ute  . - 2021. Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Menaces et Pressions Mots-clés : MICROCEBUS ARNHOLDI  ENVRIONMENTAL CHANGE  MADAGASCAR  ANTROPOGENIC IMPACT Résumé : Quaternary climatic changes have been invoked as important drivers of species diversification worldwide. However, the impact of such changes on vegetation and animal population dynamics in tropical regions remains debated. To overcome this uncertainty, we integrated high-resolution paleoenvironmental reconstructions from a sedimentary record covering the past 25,000 years with demographic inferences of a forest-dwelling primate species (Microcebus arnholdi), in northern Madagascar. Result comparisons suggest that climate changes through the African Humid Period (15.2 – 5.5 kyr) strongly affected the demographic dynamics of M. arnholdi. We further inferred a population decline in the last millennium which was likely shaped by the combination of climatic and anthropogenic impacts. Our findings demonstrate that population fluctuations in Malagasy wildlife were substantial prior to a significant human impact. This provides a critical knowledge of climatically driven, environmental and ecological changes in the past, which is essential to better understand the dynamics and resilience of current biodiversity. Titre du périodique : Communications Biology Volume : 4 : 1084 En ligne : https://doi.org/10.1038/s42003-021-02620-1

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Spatial variation in density and total size estimates in fragmented primate populations: the golden-crowned sifaka (Propithecus tattersalli) / Erwan Quéméré  

Public ISBD Titre : Spatial variation in density and total size estimates in fragmented primate populations: the golden-crowned sifaka (Propithecus tattersalli) Type de document : texte imprimé Auteurs : Erwan Quéméré, Auteur ; Julie Champeau, Auteur ; Aubin Besolo, Auteur ; Emmanuel Rasolondraibe, Auteur ; Clément Rabarivola, Auteur ; Brigitte Crouau-Roy, Auteur ; Lounès Chikhi, Auteur Année de publication : 2009 Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Biologie, Ecologie, Densité Mots-clés : GOLDEN-CROWNED SIFAKA  PROPITHECUS TATTERSALLI  HABITAT FRAGMENTATION  ABUNDANCE  EDGE EFFECT Résumé : The golden-crowned sifaka (Propithecus tattersalli) is an endangered lemur species found only in the Daraina region, a very restricted area in north-eastern Madagascar. Its forest habitat is highly fragmented and expected to suffer from significant changes in the near future. The species is poorly known and only one census study, carried out in 2000, has ever been published. It is thus crucial to update the conservation status of the golden-crowned sifaka before major anthropogenic environmental changes take place. Using the line-transect approach, we estimated the species density in the main forest fragments located in both the peripheral and central parts of the distribution range, including both protected and unprotected areas. In parallel, we tried to determine whether an edge effect could be detected by comparing densities at different distances from the forest edges. We found important variation of sifaka densities among forest fragments. The total species abundance is thus difficult to determine, but we estimated that it is likely to be over 18,000, two to three times higher than previously thought. However, our data also suggested that most P. tattersalli live in forests located in the central part of the distribution range and that the estimated densities in the central part were high (>80 individuals/km2). Two forest fragments, found to host a large part of the total population, are currently outside the managed area and their incorporation to the managed area is strongly recommended. Lastly, as expected for a folivorous and not heavily hunted species, our results are consistent with the hypothesis that this species does not experience a clear edge effect, at least during the first half of the dry season. This could be due to a high resiliency to habitat fragmentation or to the fact that fragmentation has been going on for some time. Titre du périodique : American Journal of Primatology Volume : 72: 72-80 En ligne : https://doi.org/10.1002/ajp.20754 Spatial variation in density and total size estimates in fragmented primate populations: the golden-crowned sifaka (Propithecus tattersalli) [texte imprimé] / Erwan Quéméré, Auteur ; Julie Champeau, Auteur ; Aubin Besolo, Auteur ; Emmanuel Rasolondraibe, Auteur ; Clément Rabarivola, Auteur ; Brigitte Crouau-Roy, Auteur ; Lounès Chikhi, Auteur . - 2009. Langues : Anglais (eng) Langues originales : Anglais (eng) Catégories : LEMURIENS LEMURIENS:Biologie, Ecologie, Densité Mots-clés : GOLDEN-CROWNED SIFAKA  PROPITHECUS TATTERSALLI  HABITAT FRAGMENTATION  ABUNDANCE  EDGE EFFECT Résumé : The golden-crowned sifaka (Propithecus tattersalli) is an endangered lemur species found only in the Daraina region, a very restricted area in north-eastern Madagascar. Its forest habitat is highly fragmented and expected to suffer from significant changes in the near future. The species is poorly known and only one census study, carried out in 2000, has ever been published. It is thus crucial to update the conservation status of the golden-crowned sifaka before major anthropogenic environmental changes take place. Using the line-transect approach, we estimated the species density in the main forest fragments located in both the peripheral and central parts of the distribution range, including both protected and unprotected areas. In parallel, we tried to determine whether an edge effect could be detected by comparing densities at different distances from the forest edges. We found important variation of sifaka densities among forest fragments. The total species abundance is thus difficult to determine, but we estimated that it is likely to be over 18,000, two to three times higher than previously thought. However, our data also suggested that most P. tattersalli live in forests located in the central part of the distribution range and that the estimated densities in the central part were high (>80 individuals/km2). Two forest fragments, found to host a large part of the total population, are currently outside the managed area and their incorporation to the managed area is strongly recommended. Lastly, as expected for a folivorous and not heavily hunted species, our results are consistent with the hypothesis that this species does not experience a clear edge effect, at least during the first half of the dry season. This could be due to a high resiliency to habitat fragmentation or to the fact that fragmentation has been going on for some time. Titre du périodique : American Journal of Primatology Volume : 72: 72-80 En ligne : https://doi.org/10.1002/ajp.20754

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