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"Nicolas, Violaine"
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Evolutionary history of the thicket rats (genus Grammomys) mirrors the evolution of African forests since late Miocene
by
Šumbera, Radim
,
Bryjová, Anna
,
Peterhans, Julian C. Kerbis
in
Arvicanthini
,
Bayesian analysis
,
Central Africa
2017
Aim: Grammomys are mostly arboreal rodents occurring in forests, woodlands and thickets throughout sub-Saharan Africa. We investigated whether the divergence events within the genus follow the existing evolutionary scenario for the development of African forests since the late Miocene. Location: Sub-Saharan African forests and woodlands. Methods: We inferred the molecular phylogeny of Grammomys using Bayesian and maximum likelihood methods and DNA sequences of 351 specimens collected from across the distribution of the genus. We mapped the genetic diversity, estimated the divergence times by a relaxed clock model and compared evolution of the genus with forest history. Results: Phylogenetic analysis confirms the monophyly of Grammomys and reveals five main Grammomys lineages with mainly parapatric distributions: (1) the poensis group in Guineo-Congolese forests; (2) the selousi group with a distribution mainly in coastal forests of southern and eastern Africa; (3) the dolichurus group restricted to the easternmost part of South Africa; (4) the macmillani group in the northern part of eastern and Central Africa with one isolated species in Guiñean forests; and (5) the surdaster group, widely distributed in eastern Africa south of the equator. Every group contains well supported sublineages suggesting the existence of undescribed species. The earliest split within the genus (groups 1 vs. 2-5) occurred in the late Miocene and coincides with the formation of the Rift Valley which resulted in the east-west division of the initially pan-African forest. The subsequent separation between groups (2 vs. 3-5) also dates to the end of the Miocene and suggests the split between Grammomys from coastal to upland forests in eastern Africa followed by a single dispersal event into western Africa during the Pleistocene. Conclusions: The evolutionary history of the genus Grammomys closely reflects the accepted scenario of major historical changes in the distribution of tropical African forests since the late Miocene.
Journal Article
Multilocus phylogeny of the Crocidura poensis species complex (Mammalia, Eulipotyphla) Influences of the palaeoclimate on its diversification and evolution
by
Hutterer, Rainer
,
Institut Pasteur de Côte d'Ivoire ; Pasteur Network (Réseau International des Instituts Pasteur)
,
Jacquet, François
in
allopatry
,
Arid environments
,
Aridity
2019
Aim: This study aims to reconstruct the evolutionary history of the Crocidura poensis species complex and to identify factors driving diversification within it. We tested whether: (a) there is a pattern of allopatric differentiation coincident with the location of hypothesized Pleistocene forest refugia, (b) sister taxa are separated by broad rivers, (c) sister taxa occupy adjacent but distinct habitat.Location: Sub‐Saharan African forests and adjacent savanna.Taxon: Shrews.Methods: Analyses were based on 247 specimens collected from across the distribution of the species complex. We reconstructed the phylogeny (Bayesian and maximum likelihood methods) and assessed historical biogeography of this taxonomic group using a combination of mitochondrial and nuclear markers. We mapped the genetic diversity and estimated the divergence times by a relaxed clock model. Informed by multilocus species delimitation methods, we discussed possible taxonomic implications.Results: This complex is composed of nine major genetic lineages (proposed species). The earliest split within this complex occurred after 2.0–2.4 Ma, which corresponds to a period of increased aridity and/or extreme environmental variability. Most other divergence events occurred after the Early‐Middle Pleistocene Transition (1.2–0.8 Ma). Divergent selection across ecological gradients could explain diversification within the West African lineage. In Central Africa, the observed phylogeographic pattern fits the Pleistocene refuge hypothesis and supports the existence of multiple small rather than a few large forest refugia during glacial maxima. Large rivers, like the Congo and Sanaga Rivers, are important barriers to gene flow for several lineages but probably were not the primary cause of differentiation.Main conclusions: Both geographic isolation in distinct forest refugia and divergent selection along ecological gradients could explain Pleistocene diversification within this complex.
Journal Article
Defining Fragmentation Patterns of Archaeological Bone Remains without Typologies: A Landmark-Based Approach on Rodent Mandibula
by
Maestri, Renan
,
Durocher, Marine
,
Nicolas, Violaine
in
Animal biology
,
Animal models
,
Archaeology
2022
Fragmentation is a recurring feature of archaeological faunal material, and impacts many aspects of zooarchaeological studies from taxonomical identification to biometric studies. It can result from anthropic and natural actions that occurred respectively before and/or after bone deposit. While several bone fragmentation typologies have been described, they are currently based on both macroscopic observations and researcher subjectivity and lack the universality necessary for inter-study comparisons. To fulfill this need we present a standardized landmark-based protocol for the description and quantification of mandibular fragmentation patterns, using two insular rodents of different sizes as models. The rice rats (Oryzomyini tribe) and the agouti (Dasyprocta) from the Lesser Antilles were abundant during the pre-Columbian Ceramic Age (500 BCE-1500 CE). Their mandibles’ shapes were quantified using the coordinates of 13 2D-landmarks. We show that landmark-based measurements can be used to:—assess the preservation differences between taxa of the same taxonomic group (e.g., rodents),—estimate the level of preservation of a skeletal part (e.g., mandible),—describe fragmentation patterns without pre-existing typologies and—facilitate the application of geometric morphometric methods to fragmented archaeological material. Our novel approach, leveraging fragmentation analyses and establishing specific fragmentation patterns, frees itself from existing typologies and could be systematically applied to future research.
Journal Article
A Remarkable Case of Micro-Endemism in Laonastes aenigmamus (Diatomyidae, Rodentia) Revealed by Nuclear and Mitochondrial DNA Sequence Data
by
Keovichit, Kham
,
Herbreteau, Vincent
,
Hugot, Jean-Pierre
in
Animal biology
,
Animal genetics
,
Animals
2012
L. aenigmamus is endemic to the limestone formations of the Khammuan Province (Lao PDR), and is strongly specialized ecologically. From the survey of 137 individuals collected from 38 localities, we studied the phylogeography of this species using one mitochondrial (Cyt b) and two nuclear genes (BFIBR and GHR). Cyt b analyses reveal a strong mtDNA phylogeographical structure: 8 major geographical clades differing by 5-14% sequence divergence were identified, most of them corresponding to distinct karst areas. Nuclear markers display congruent results but with a less genetic structuring. Together, the data strongly suggest an inland insular model for Laonastes population structure. With 8 to 16 evolutionary significant units in a small area (about 200×50 km) this represents an exceptional example of micro-endemism. Our results suggest that L. aenigmamus may represent a complex of species and/or sub-species. The common ancestor of all Laonastes may have been widely distributed within the limestone formations of the Khammuan Province at the end of Miocene/beginning of the Pliocene. Parallel events of karst fragmentation and population isolation would have occurred during the Pleistocene or/and the end of the Pliocene. The limited gene flow detected between populations from different karst blocks restrains the likelihood of survival of Laonastes. This work increases the necessity for a strict protection of this rare animal and its habitat and provides exclusive information, essential to the organization of its protection.
Journal Article
Phylogeographic structure and regional history of Lemniscomys striatus (Rodentia: Muridae) in tropical Africa
by
Verheyen, Erik
,
Lecompte, Emilie
,
Olayemi, Ayodeji
in
Africa
,
Animal and plant ecology
,
Animal, plant and microbial ecology
2008
Aim This study aims to elucidate the phylogeography of the murid rodent Lemniscomys striatus and to evaluate the relative roles of ecological change, habitat patchiness, rivers and geological barriers in structuring patterns of diversity. Location Sub-Saharan Africa. Methods The extent of phylogeographic patterns and molecular genetic diversity (cytochrome b gene) were addressed in a survey of 128 individuals of L. striatus from 42 localities. Using maximum parsimony, maximum likelihood, Bayesian, network and genetic structure analyses, we inferred intraspecific relationships and tested hypotheses for historical patterns of gene flow within L. striatus. Results Our results identified four major geographical clades within L. striatus: a West African clade, a Benin-Nigeria clade, a Central African clade, and an East African clade. Several subclades were identified within these four major clades. Restricted gene flow with isolation by distance was recorded, which is congruent with the low dispersal ability of such a small murid rodent. No clear signal of population expansion was detected within clades or subclades. Main conclusions The western rift system and the Volta and Niger rivers may have acted as long-term extrinsic barriers to gene flow, resulting in the emergence of the four main clades of L. striatus. The observed pattern of mitochondrial variation observed within each clade probably results from late Pleistocene climatic and vegetation changes: during adverse conditions (forest expansion), L. striatus may have survived only in refugia, and then experienced range expansion under favourable conditions (savanna expansion).
Journal Article
Molecular Phylogeny of Hantaviruses Harbored by Insectivorous Bats in Côte d’Ivoire and Vietnam
2014
The recent discovery of genetically distinct hantaviruses in multiple species of shrews and moles prompted a further exploration of their host diversification by analyzing frozen, ethanol-fixed and RNAlater®-preserved archival tissues and fecal samples from 533 bats (representing seven families, 28 genera and 53 species in the order Chiroptera), captured in Asia, Africa and the Americas in 1981–2012, using RT-PCR. Hantavirus RNA was detected in Pomona roundleaf bats (Hipposideros pomona) (family Hipposideridae), captured in Vietnam in 1997 and 1999, and in banana pipistrelles (Neoromicia nanus) (family Vespertilionidae), captured in Côte d’Ivoire in 2011. Phylogenetic analysis, based on the full-length S- and partial M- and L-segment sequences using maximum likelihood and Bayesian methods, demonstrated that the newfound hantaviruses formed highly divergent lineages, comprising other recently recognized bat-borne hantaviruses in Sierra Leone and China. The detection of bat-associated hantaviruses opens a new era in hantavirology and provides insights into their evolutionary origins.
Journal Article
Seasonal variations in population and community structure of small rodents in a tropical forest of Gabon
by
Nicolas, Violaine
,
Colyn, Marc
in
Animal and plant ecology
,
Animal breeding
,
Animal populations
2003
The composition, structure, and reproductive phenology of a community of murid rodents were investigated for 1 year at two sites in an undisturbed forest in southwestern Gabon, Africa. We captured 1531 mice belonging to 11 species and eight genera. At both sites, species richness varied seasonally and tended to be maximal during the period of maximal trap success. For the most abundant species (Hylomyscus stella, Hybomys univittatus, Heimyscus fumosus, and Praomys cf. misonnei), a general unimodal trend in trap success was detected, owing to variations in breeding activity and survival, with a minimum around the long rainy season and a maximum either during the short rainy season or at the beginning of the following long dry season. These fluctuations varied in magnitude among species, and seasonal variations in relative abundance were recorded. Our results support the assumption that in the tropics, rainfall and associated patterns of fruit and insect abundance are important factors which may act directly or indirectly to initiate breeding activity so that lactation occurs at a time of greatest food abundance. Finally, intrapopulational differences in age at sexual maturity were found, both between the sexes and among individuals of the same sex.
Journal Article
Interrogating Phylogenetic Discordance Resolves Deep Splits in the Rapid Radiation of Old World Fruit Bats (Chiroptera: Pteropodidae)
2021
The family Pteropodidae (Old World fruit bats) comprises >200 species distributed across the Old World tropics and subtropics. Most pteropodids feed on fruit, suggesting an early origin of frugivory, although several lineages have shifted to nectar-based diets. Pteropodids are of exceptional conservation concern with >50% of species considered threatened, yet the systematics of this group has long been debated, with uncertainty surrounding early splits attributed to an ancient rapid diversification. Resolving the relationships among the main pteropodid lineages is essential if we are to fully understand their evolutionary distinctiveness, and the extent to which these bats have transitioned to nectar-feeding. Here we generated orthologous sequences for >1400 nuclear protein-coding genes (2.8 million base pairs) across 114 species from 43 genera of Old World fruit bats (57% and 96% of extant species- and genus-level diversity, respectively), and combined phylogenomic inference with filtering by information content to resolve systematic relationships among the major lineages. Concatenation and coalescent-based methods recovered three distinct backbone topologies that were not able to be reconciled by filtering via phylogenetic information content. Concordance analysis and gene genealogy interrogation show that one topology is consistently the best supported, and that observed phylogenetic conflicts arise from both gene tree error and deep incomplete lineage sorting. In addition to resolving long-standing inconsistencies in the reported relationships among major lineages, we show that Old World fruit bats have likely undergone at least seven independent dietary transitions from frugivory to nectarivory. Finally, we use this phylogeny to identify and describe one new genus.
Journal Article
Genetic variation of the most abundant forest‐dwelling rodents in Central Africa ( Praomys jacksoni complex): Evidence for Pleistocene refugia in both montane and lowland forests
by
Denys, Christiane, C
,
University of Liverpool
,
Verheyen, Erik
in
Bayesian analysis
,
Bayesian theory
,
Cameroon
2019
Aim We investigate the Plio‐Pleistocene evolutionary history of one of the most abundant rodents in Afrotropical forests. Specifically, we ask how their diversification was influenced by climate change, topography and major rivers. Location Tropical Africa: Lower Guinea (including Cameroon volcanic line; CVL), Congolia, Albertine Rift (AR), Kenyan highlands (KH). Taxon Murine rodents of the Praomys jacksoni complex. Methods We used 849 genotyped individuals to describe the overall diversity and spatial genetic structure across a majority of their known distribution area. The combination of one mitochondrial and three nuclear markers was used to infer dated phylogenies using Bayesian and maximum likelihood approaches. Genetic structure was further assessed by multispecies coalescent species delimitation. Current and past distributions of particular taxa were predicted using environmental niche modelling. Results The complex is composed of five major genetic clades (proposed species). Two of them are restricted to specific habitat types (either montane forests of AR or wetlands in lowland forests along the Congo River), three others have wide geographic distributions and lower levels of ecological specialization. The earliest divergence is dated to the Plio‐Pleistocene boundary and is in accordance with the separation of AR forests and Guineo‐Congolian forests. Further diversification of the complex is associated with Pleistocene climate changes. Relatively stable refugia of suitable climatic conditions were identified in lowland Congolia (for two species currently distributed only in lowland forests) as well as in montane forests of CVL, AR, KH (playing the role of reservoirs of diversity). Large rivers, especially the Congo River, are important barriers to gene flow for most taxa, but probably were not the primary cause of differentiation. Main conclusions The evolutionary history of the complex was primarily affected by Pleistocene climate changes and diversification in forest refugia. There is little support for ecological parapatric speciation or the riverine barrier hypothesis.
Journal Article
Seasonal variation in population and community structure of shrews in a tropical forest of Gabon
by
Nicolas, Violaine
,
Barrière, Patrick
,
Colyn, Marc
in
Africa
,
Animal and plant ecology
,
Animal traps
2005
The composition, structure and reproductive phenology of a shrew community were investigated for 1 y at two neighbouring sites in an undisturbed African forest of south-western Gabon. We captured 717 shrews, belonging to four genera and 10 species. The data were analysed to answer three main questions: (1) to what extent does the shrew abundance vary seasonally? (2) is there a shift in species dominance over time? and (3) does the intensity of breeding activity vary seasonally? The number of species captured varied seasonally and tended to be least during the period of minimal trap success. Trap success for the four most abundant species (Sylvisorex johnstoni, Crocidura batesi, Paracrocidura schoutedeni and Sylvisorex ollula) varied seasonally with a minimum around the long dry season. Sylvisorex johnstoni remained the dominant species throughout the year. Seasonal variation in trap success of shrews might be related, at least partly, to their reproductive characteristics. Litter size, based on embryo counts, ranged from 1–4 among the species. Breeding occurred throughout the year, but its intensity was lower during the long dry season corresponding with the period of higher ecological constraints for shrews.
Journal Article