Accueil > Annuaire et pages personnelles > Pages Personnelles

HENNEQUIN Sabine

Sabine Hennequin












Maitre de conférences/Assistant professor
Muséum National d’Histoire Naturelle
Institut de Systématique, Evolution, Biodiversité
ISYEB - UMR 7205 CNRS, MNHN, UPMC, EPHE
Université Pierre et Marie Curie, Sorbonne Universités
Equipe Diversité, Evolution végétale et fongique
57 rue Cuvier - CP48
F-75005 Paris, France
☏ : (+33)1.40.79.80.58.
Fax : (+33)1.40.79.37.39
contact :sabine.hennequin@upmc.fr


bandeau en tete

 

Research

I study evolutionary patterns and processes in seed-free plants belonging to the ferns and lycophytes. This involves reconstructing evolutionary relationships between lineages (phylogenies), which can be used to understand morphological evolution, biogeography and adaptation to particular habitats. Whenever available, fossils are used to calibrate these phylogenies, thus providing the time scale for evolutionary events. A second part of my research interests focuses on the assembly of diversity on oceanic islands, in other words, its geographical whereabouts, the role of immigration or speciation and how it is phylogenetically structured.


The assembly of fern diversity in the Mascarene Islands


1 Mountain canopy


Photo 1 Mountain rainforest at La Grande Montée, with the tree ferns Cyathea glauca emerging from the canopy © S. Hennequin

The Mascarene Islands consist of three main islands (La Réunion, Mauritius and Rodrigues) located east of Madagascar in the Indian Ocean and part of the South West Indian Ocean hotspot of biodiversity and endemism. Although these oceanic islands share similar geological history, they differ in size, elevation profile, age, distance to the nearest larger land mass (Madagascar) and biodiversity. Ferns are well known for their high dispersal capacity as a result of their reproductive biology, which includes the formation of small meiospores and potentially hermaphrodite gametophytes. Consequently, frequent colonization by ferns from Madagascar and other areas around the Indian Ocean, or even further, is expected, as well as exchange between the Mascarene islands. Indeed, ferns make up an important component of the diverse flora of the Mascarenes, especially in the rain forests, with more than 240 reported species, among which 20% are endemic to these islands. After the Hawaiian Islands, the Mascarenes are the oceanic islands with the highest fern diversity, making them especially suited to study fern evolution in a real-scale Darwinian laboratory. The objectives of this study are multiple : to investigate the patterns of fern diversification in the Mascarene Islands, especially groups undergoing cladogenesis, to identify the processes of island community assembly and to investigate characteristics (such as morphology and life forms) that may be related to better chances of colonization versus speciation.


Erica mountain

Photo 2 Erica mountain thicket with Sphagnum (“avoune” type) © L. Echternacht.

Cyathea glauca

Photo 3 Cyathea glauca (Cyatheaceae) or “fanjan femelle”, an emblematic tree fern endemic to La Réunion © S. Hennequin.

This project has been funded by two ATM of the MNHN Paris (2010-2012), the British Council Darwin Now Award (2009), and a Marie Curie Intra-European Fellowship (2008-2010).

This project is currently expanded to the whole South-West Indian Ocean Region, including Madagascar, in collaboration with G. Rouhan. In addition, we are collaborating with a Brazilian team (A. Salino, UFMG Brazil) with a view to comparing how fern diversity is assembled in two geographically distinct areas sharing similar ecology : the Indian Ocean region and the Atlantic Forest in Brazil.

 Fern systematics, biogeography and evolution

In relation to my project on the ferns from the Mascarene Islands, I am interested in reconstructing the evolutionary relationships in several groups of ferns, especially the genus Ctenitis (Dryopteridaceae) which appears to have radiated in the Indian Ocean region and in the Mascarenes, and the families Thelypteridaceae and Polypodiaceae.
Main coll. : H. Schneider (NHM London), J.-Y. Dubuisson, M. Gaudeul & G. Rouhan (UMR 7205), A. Salino (UFMG, Brazil), A. Ebihara (National Museum of Nature and Science,Tokyo, T. Ranker (U. of Colorado).

bandeau photos 4_5_6 entete

Photo 4 Amauropelta heteroptera (Thelypteridaceae), endemic to La Réunion © L. Echternacht.

Photo 5 Grammitis melanoloma (Polypodiaceae), an epiphyte endemic to La Réunion, showing round nude sori and characterized by a black margin © L.Echternacht.

Photo 6 Ctenitis crinita (Dryopteridaceae) and sori, endemic to Mauritius. According to our results this genus radiated in the Mascarenes. © L. Echternacht.

This is not to forget my first research interest : the Hymenophyllaceae, or filmy ferns, easily recognized by their very thin leaves (typically one-cell thick) and their marginal sori. During my Ph.D. I studied a genus of the family, Hymenophyllum, which includes approximately 300 species. The phylogeny inferred allowed to propose a new classification for the genus. I was also especially interested in the evolution of morphological characters within the genus, and deciphering its complex biogeographical history is still underway. This requires broadening the taxon sampling of the inferred phylogeny and acquiring nuclear markers. I also draw my attention to the issue of chromosome numbers evolution in the genus, where very variable numbers are reported with n = 11, 12, 13, 14, 18, 21, 22, 26, 28, 36. (coll. J.-Y. Dubuisson, UMR7205 and A. Ebihara, National Museum of Nature and Science, Japan).

photo 7 Hymenophyllum decurrens







Photo 7 Hymenophyllum decurrens (Hymenophyllaceae) from Guadeloupe grows as an epiphyte, as nearly all other Hymenophyllum species © J.-Y. Dubuisson





fig 8





Fig 8 Chromosome number evolution in Hymenophyllum.





fig9 HabitatHymenophyllaceae

Another project targeted molecular rate heterogeneity between the two lineages of Hymenophyllaceae : hymenophylloids (= Hymenophyllum) and trichomanoids. We demonstrated that there is a slow-down in the molecular evolutionary rate in the hymenophylloids, and that this phenomenon occurs not only at the chloroplast level, but also seems to take place on the mitochondrion and nuclear levels. With a view to understanding the causes for this deceleration of rate, we investigated the evolutionary history in the family by estimating divergence times and by reconstructing the evolution of the different habitats found in the family (terrestrial, hemiepiphytic and epiphytic). Our results imply that filmy ferns were ancestrally terrestrial and that epiphytism evolved several times independently in the family during the Cretaceous and the Tertiary. Coll. K. Pryer (Duke University) and E. Schuettpelz (U. North Carolina).
Together with J.-Y. Dubuisson, we are further investigating morphological and anatomical evolution in the trichomanoids in relation to habitat. We also aim to propose a biogeographical scenario for the history of the lineage.

Fig 9 Habitat evolution and divergence times in Hymenophyllaceae.

photo10 collecting clenitis

  Fieldwork

Fieldwork is an essential part of my work in order to obtain material of the studied species and to understand their ecological preferences. Collected specimens are preserved as herbarium specimen, contributing to enriching the herbarium collections of the MNHN Paris, and as silica-dried material for DNA-based studies.

Mata Atlantica, Brazil : 2013

La Réunion : 2002, 2009, 2010

Mauritius : 2009, 2010

Guadeloupe : 2006

Canary Islands : 2010

Madeira : 2004

Photo 10 Collecting Ctenitis maritima in La Réunion (endemic to the Mascarenes) © L. Echternacht.

 Teaching

- Current teaching at the Université Pierre et Marie Curie :
Licence Sciences du Vivant 1st, 2n and 3rd year : Plant biodiversity, morphology, and anatomy.
Master Sciences de l’Univers, Environnement, Ecologie : Plant systematics and ecology, Forest sciences, Phylogeny and evolution, Plant systematics, Tropical diversity
Master in Biology Teaching : Botany

 Professional expérience

- Since september 2009 - Assistant Professor, Université Pierre et Marie Curie, Paris.

- 2008-2009 - Post-doctoral researcher, NHM London, UK
Project : Investigating the fern diversity of the Mascarene Islands
Supervisor : H. Schneider

- 2005-2007 - Post-doctoral researcher, Duke University, USA
Project : Molecular rate heterogeneity and evolutionary history in the Hymenophyllaceae Supervisor : K Pryer

- 2003-2005 - Lecturer (ATER), Université Pierre et Marie Curie, France.

- 1999-2004 - Ph.D. Université Pierre et Marie Curie, France
Project : Phylogenetic systematics of the fern genus Hymenophyllum (Hymenophyllaceae) Supervisor : J.-Y. Dubuisson.



 Publications

PDF - 313.8 ko

- Hennequin S., Kessler M., Lindsay S. & Schneider H. 2014. Evolutionary patterns in the assembly of fern diversity on the oceanic Mascarene Islands. Journal of Biogeography 41 : 1651-1663 (cover picture).

- Dubuisson J.-Y., Bary S., Ebihara A., Carnero-Diaz E., Boucheron-Dubuisson E. ; & Hennequin S. 2013. Epiphytism, anatomy and regressive evolution in trichomanoid filmy ferns (Hymenophyllaceae). Botanical Journal of the Linnean Society 173 : 573-593.

- Liu H.-M., Jiang R.-H., Guo J., Hovenkamp P., Perrie L.R., Shepherd L., Hennequin S. & Schneider H. 2013. Towards a phylogenetic classification of the climbing fern genus Arthropteris. Taxon 62 : 688-700.

- Dubuisson J.-Y., Rouhan G, Grall A., Hennequin S., Senterre B, Pynee K., & Ebihara A. 2013. New insights into the systematics and evolution of the filmy fern genus Crepidomanes (Hymenophyllaceae) in the Mascarene Archipelago with a focus on dwarf species. Acta Botanica Gallica : Botany Letters 160 : 173-194.

- Pynee K., Dubuisson J.-Y. & Hennequin S. 2013. Flora diversity of Mount Bar Le Duc Volcanic Crater (Ripailles Hill), Nouvelle Découverte, Mauritius. Cahiers scientifiques de l’Océan Indien occidental 4 : 15-20.

- Schneider H., He L., Hennequin S. & Zhang X.-C. 2013. Towards a natural classification of Pteridaceae : inferring the relationships of enigmatic pteridoid fern species occurring in the Sino-Himalaya and Afro-Madagascar. Phytotaxa 77 : 49-60.

- Schneider H., He L., Marquardt J., Wang L., Heinrichs J., Hennequin S. & Zhang X.-C. 2013. Exploring the origin of the latitudinal diversity gradient : Contrasting the sister fern genera Phegopteris and Pseudophegopteris. Journal of Systematics and Evolution 51 : 61-70.

- Pynee K, Hennequin S, Echternacht L & Dubuisson J-Y. 2012. A new local variety of Crepidomanes minutum (Hymenophyllaceae) in the Mascarene archipelago (Indian Ocean) and a new record for Mauritius. Phytotaxa 62 : 25–30.

- Dubuisson J.-Y., Hennequin S., Bary S., Ebihara A. & Boucheron-Dubuisson E. 2011. Anatomy diversity and regressive evolution in trichomanoid filmy ferns (Hymenophyllaceae) : a phylogenetic approach. Comptes Rendus Biologies 334 : 880-895.

- Hennequin S., Hovenkamp P., Christenhusz M. & H. Schneider. Phylogeny and biogeography of Nephrolepis - A tale of old settlers and young tramps. Botanical Journal of the Linnean Society 164 : 113-127

- Hennequin S., Ebihara A., Ito M., Dubuisson J.-Y. & H. Schneider. 2010. Chromosome number evolution in Hymenophyllum (Hymenophyllaceae), with special reference to the subgenus Hymenophyllum. Molecular Phylogenetics and Evolution 55 : 47-59-

- Dubuisson J.-Y., Schneider, H. & Hennequin S (2009) Epiphytism in ferns : diversity and history Comptes Rendus Biologies 332 : 120-128

- Hennequin S., Pryer K., Schuettpelz E., Ebihara, A. & Dubuisson J.-Y (2008) Divergence times and the evolution of epiphytism in filmy ferns (Hymenophyllaceae) revisited International Journal of Plant Sciencess169 : 1278-1287. doi:10.1086/591983

- Ebihara A., Iwatsuki K., Hennequin S., Ito M. & Dubuisson J.-Y (2007) Phylogeny of the fern genus Trichomanes (Hymenophyllaceae) : global sampling, molecular approach and re-evaluation of morphologyBotanical journal of the Linnean Society 155 : 1-27doi:10.1111/j.1095-8339.2007.00684.x].

- Ebihara A., Dubuisson J.-Y., Iwatsuki K., Hennequin S. & Ito M (2006) A taxonomic revision of the Hymenophyllaceae Blumea 51 : 221-280. Blumea-

- Hennequin S., Ebihara A., Ito M., Iwatsuki K., & Dubuisson J.-Y (2006) New insights into the phylogeny of Hymenophyllum (Hymenophyllaceae) : revealing the polyphyly of Mecodium Systematic Botany 31 : 271-284. doi:10.1600/036364406777585775

- Hennequin S., Ebihara A., Ito M., Iwatsuki K., & Dubuisson J.-Y. (2006) Phylogenetic systematics and evolution of the genus Hymenophyllum (Hymenophyllaceae : Pteridophyta), Fern Gazette

- Ebihara A., Hennequin S., Iwatsuki K., Bostock P., Matsumoto S., Jaman R., Dubuisson J.-Y., & Ito M. (2004) Polyphyletic origin of Microtrichomanes (Mett. Ex Prantl) Copel. (Hymenophyllaceae) with a revision of the species Taxon 53 : 935-948. Taxon

- Dubuisson J.-Y., Hennequin S., Douzery E. J. P., Pryer K. M., Cranfill R., & Smith A. R. (2003) Molecular systematics of the fern genus Trichomanes L. (Hymenophyllaceae) with special reference to neotropical taxa International Journal of Plant Science 164 : 753-761. doi:10.1086/377059.

- Dubuisson J.-Y., Hennequin S., Rakotondrainibe F. & Schneider H (2003) Ecological diversity and adaptative tendencies in the tropical fern genus Trichomanes L. (Hymenophyllaceae) with special reference to climbing habit Botanical Journal of the Linnean Society 142 : 41-63. doi:10.1046/j.1095-8339.2003.00165.x

- Hennequin S (2003) Phylogenetic relationships within the fern genus Hymenophyllum s.l. (Hymenophyllaceae, Filicopsida) : contribution of morphology and cytology Comptes Rendus Biologies 326 : 599-611. doi:10.1016/S1631-0691(03)00146-X

- Hennequin S., Ebihara A., Ito M., Iwatsuki K. & Dubuisson J.-Y. (2003) Molecular systematics of the fern genus Hymenophyllum s.l. (Hymenophyllaceae) based on chloroplastic coding and noncoding regions Molecular Phylogenetics and Evolution 27 : 283-301. doi:10.1016/S1055-7903(02)00404-9

 Book chapter

Schneider H., Janssen T., Byrstiakova N., Heinrichs J., Hennequin S. & Rakotondrainibe F. 2010. Rapid radiations and neoendemism in the Madagascan biodiversity hotpsot. In Evolution in Action. M. Glaubrecht (ed.), Springer-Verlag, Berlin Heidelberg.

 Book review

Hennequin S. & Schneider H. 2009. Biology and Evolution of Ferns and Lycophytes by T.A. Ranker & C. H. Haufler (eds). Botanical Journal of the Linnean Society 161, p. 451-452.





publié le , mis à jour le