19 research outputs found
Digest:The role of postzygotic isolation in Mimulus speciation
Recently diverged species often show incomplete reproductive isolation and subsequently experience hybridization and introgression. The plant genus Mimulus includes many such examples of closely related taxa that prove useful for studying incipient speciation. However, Sandstedt et al. show that in contrast to other Mimulus species, species of the M. tilingii complex are characterized by strong postzygotic isolation mediated by multiple barriers. This finding highlights the diverse speciation histories of related plant groups
Measuring, comparing and interpreting phenotypic selection on floral scent
Natural selection on floral scent composition is a key element of the hypothesis that pollinators and other floral visitors drive scent evolution. The measure of such selection is complicated by the high-dimensional nature of floral scent data and uncertainty about the cognitive processes involved in scent-mediated communication. We use dimension reduction through reduced-rank regression to jointly estimate a scent composite trait under selection and the strength of selection acting on this trait. To assess and compare variation in selection on scent across species, time and space, we reanalyse 22 datasets on six species from four previous studies. The results agreed qualitatively with previous analyses in terms of identifying populations and scent compounds subject to stronger selection but also allowed us to evaluate and compare the strength of selection on scent across studies. Doing so revealed that selection on floral scent was highly variable, and overall about as common and as strong as selection on other phenotypic traits involved in pollinator attraction or pollen transfer. These results are consistent with an important role of floral scent in pollinator attraction. Our approach should be useful for further studies of plant-animal communication and for studies of selection on other high-dimensional phenotypes. In particular, our approach will be useful for studies of pollinator-mediated selection on complex scent blends comprising many volatiles, and when no prior information on the physiological responses of pollinators to scent compounds is available
Measuring, comparing and interpreting phenotypic selection on floral scent
Natural selection on floral scent composition is a key element of the hypothesis that pollinators and other floral visitors drive scent evolution. The measure of such selection is complicated by the high-dimensional nature of floral scent data and uncertainty about the cognitive processes involved in scent-mediated communication. We use dimension reduction through reduced-rank regression to jointly estimate a scent composite trait under selection and the strength of selection acting on this trait. To assess and compare variation in selection on scent across species, time and space, we reanalyse 22 datasets on six species from four previous studies. The results agreed qualitatively with previous analyses in terms of identifying populations and scent compounds subject to stronger selection but also allowed us to evaluate and compare the strength of selection on scent across studies. Doing so revealed that selection on floral scent was highly variable, and overall about as common and as strong as selection on other phenotypic traits involved in pollinator attraction or pollen transfer. These results are consistent with an important role of floral scent in pollinator attraction. Our approach should be useful for further studies of plant-animal communication and for studies of selection on other high-dimensional phenotypes. In particular, our approach will be useful for studies of pollinator-mediated selection on complex scent blends comprising many volatiles, and when no prior information on the physiological responses of pollinators to scent compounds is available.Peer reviewe
Diversification of Mediterranean orchids : pollination niches, floral trait evolution and integrative taxonomy
Les interactions avec les pollinisateurs font partie de la niche Ă©cologique des orchidĂ©es et ont jouĂ© un rĂŽle dans leur diversification taxonomique et florale. Au cours de cette thĂšse, jâai dâabord analysĂ© lâarchitecture du rĂ©seau orchidĂ©es-pollinisateurs en rĂ©gion Euro-MĂ©diterranĂ©enne et montrĂ© que la similaritĂ© de niches de pollinisation entre orchidĂ©es Ă©tait fonction de leur distribution spatio-temporelle, suggĂ©rant un certain opportunisme dans les interactions orchidĂ©es-pollinisateurs. Je me suis ensuite intĂ©ressĂ©e au rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux dans deux groupes dâorchidĂ©es. Jâai dâabord montrĂ© une diffĂ©rentiation dans les traits floraux des trois taxa du groupe Anacamptis coriophora, probablement causĂ©e et maintenue par un processus de sĂ©lection divergente. En cartographiant les interactions avec les pollinisateurs et les odeurs florales sur la phylogĂ©nie de la section Pseudophrys, jâai ensuite montrĂ© que l'Ă©volution de l'odeur florale Ă©tait conditionnĂ©e par une sĂ©lection exercĂ©e par les pollinisateurs et par des contraintes phylogĂ©nĂ©tiques. Enfin, jâai mis au point une dĂ©marche de taxonomie intĂ©grative basĂ©e sur des donnĂ©es molĂ©culaires, morphomĂ©triques et chimiques dans le genre Ophrys. Avec cette dĂ©marche, jâai confirmĂ© le rang taxonomique des trois espĂšces du groupe O. insectifera et proposĂ© de fusionner deux paires dâespĂšces parmi les Pseudophrys. Une meilleure comprĂ©hension des facteurs qui façonnent la niche de pollinisation et du rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux et la spĂ©ciation chez les orchidĂ©es Euro-MĂ©diterranĂ©ennes devrait nous permettre dâamĂ©liorer la conservation de ces espĂšces emblĂ©matiques.Interactions with pollinators are part of orchidsâ ecological niches and have played a role in their taxonomic and floral diversification. During this thesis, I have analysed the architecture of the orchid-pollinator network in the Euro-Mediterranean region and shown that similarity in pollination niches between orchids primarily depends on their spatio-temporal distribution, suggesting that orchid-pollinator interactions are more opportunistic than previously thought. Then, I have been interested in the role of pollinators in floral trait evolution in two orchid groups. I have shown a differentiation in floral traits of the three taxa of the Anacamptis coriophora group, probably caused and maintained by a process of divergent selection. Then, by mapping interactions with pollinators and floral odours on the phylogeny of the section Pseudophrys, I have shown that floral odour evolution is conditioned by pollinator-mediated selection and by phylogenetic constraints. Finally, I have developed an integrative taxonomic approach based on molecular, morphometric and chemical data in the genus Ophrys. With this approach, I have confirmed the taxonomic rank of the three species of the O. insectifera group and proposed to merge two species pairs among Pseudophrys. A better understanding of the factors that have shaped pollination niches and of the role of pollinators in floral trait evolution and speciation in Euro-Mediterranean orchids should allow us to improve the conservation of these emblematic species
Diversification des orchidées méditerranéennes : niches de pollinisation, évolution des traits floraux et taxonomie intégrative
Interactions with pollinators are part of orchidsâ ecological niches and have played a role in their taxonomic and floral diversification. During this thesis, I have analysed the architecture of the orchid-pollinator network in the Euro-Mediterranean region and shown that similarity in pollination niches between orchids primarily depends on their spatio-temporal distribution, suggesting that orchid-pollinator interactions are more opportunistic than previously thought. Then, I have been interested in the role of pollinators in floral trait evolution in two orchid groups. I have shown a differentiation in floral traits of the three taxa of the Anacamptis coriophora group, probably caused and maintained by a process of divergent selection. Then, by mapping interactions with pollinators and floral odours on the phylogeny of the section Pseudophrys, I have shown that floral odour evolution is conditioned by pollinator-mediated selection and by phylogenetic constraints. Finally, I have developed an integrative taxonomic approach based on molecular, morphometric and chemical data in the genus Ophrys. With this approach, I have confirmed the taxonomic rank of the three species of the O. insectifera group and proposed to merge two species pairs among Pseudophrys. A better understanding of the factors that have shaped pollination niches and of the role of pollinators in floral trait evolution and speciation in Euro-Mediterranean orchids should allow us to improve the conservation of these emblematic species.Les interactions avec les pollinisateurs font partie de la niche Ă©cologique des orchidĂ©es et ont jouĂ© un rĂŽle dans leur diversification taxonomique et florale. Au cours de cette thĂšse, jâai dâabord analysĂ© lâarchitecture du rĂ©seau orchidĂ©es-pollinisateurs en rĂ©gion Euro-MĂ©diterranĂ©enne et montrĂ© que la similaritĂ© de niches de pollinisation entre orchidĂ©es Ă©tait fonction de leur distribution spatio-temporelle, suggĂ©rant un certain opportunisme dans les interactions orchidĂ©es-pollinisateurs. Je me suis ensuite intĂ©ressĂ©e au rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux dans deux groupes dâorchidĂ©es. Jâai dâabord montrĂ© une diffĂ©rentiation dans les traits floraux des trois taxa du groupe Anacamptis coriophora, probablement causĂ©e et maintenue par un processus de sĂ©lection divergente. En cartographiant les interactions avec les pollinisateurs et les odeurs florales sur la phylogĂ©nie de la section Pseudophrys, jâai ensuite montrĂ© que l'Ă©volution de l'odeur florale Ă©tait conditionnĂ©e par une sĂ©lection exercĂ©e par les pollinisateurs et par des contraintes phylogĂ©nĂ©tiques. Enfin, jâai mis au point une dĂ©marche de taxonomie intĂ©grative basĂ©e sur des donnĂ©es molĂ©culaires, morphomĂ©triques et chimiques dans le genre Ophrys. Avec cette dĂ©marche, jâai confirmĂ© le rang taxonomique des trois espĂšces du groupe O. insectifera et proposĂ© de fusionner deux paires dâespĂšces parmi les Pseudophrys. Une meilleure comprĂ©hension des facteurs qui façonnent la niche de pollinisation et du rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux et la spĂ©ciation chez les orchidĂ©es Euro-MĂ©diterranĂ©ennes devrait nous permettre dâamĂ©liorer la conservation de ces espĂšces emblĂ©matiques
Diversification des orchidées méditerranéennes : niches de pollinisation, évolution des traits floraux et taxonomie intégrative
Interactions with pollinators are part of orchidsâ ecological niches and have played a role in their taxonomic and floral diversification. During this thesis, I have analysed the architecture of the orchid-pollinator network in the Euro-Mediterranean region and shown that similarity in pollination niches between orchids primarily depends on their spatio-temporal distribution, suggesting that orchid-pollinator interactions are more opportunistic than previously thought. Then, I have been interested in the role of pollinators in floral trait evolution in two orchid groups. I have shown a differentiation in floral traits of the three taxa of the Anacamptis coriophora group, probably caused and maintained by a process of divergent selection. Then, by mapping interactions with pollinators and floral odours on the phylogeny of the section Pseudophrys, I have shown that floral odour evolution is conditioned by pollinator-mediated selection and by phylogenetic constraints. Finally, I have developed an integrative taxonomic approach based on molecular, morphometric and chemical data in the genus Ophrys. With this approach, I have confirmed the taxonomic rank of the three species of the O. insectifera group and proposed to merge two species pairs among Pseudophrys. A better understanding of the factors that have shaped pollination niches and of the role of pollinators in floral trait evolution and speciation in Euro-Mediterranean orchids should allow us to improve the conservation of these emblematic species.Les interactions avec les pollinisateurs font partie de la niche Ă©cologique des orchidĂ©es et ont jouĂ© un rĂŽle dans leur diversification taxonomique et florale. Au cours de cette thĂšse, jâai dâabord analysĂ© lâarchitecture du rĂ©seau orchidĂ©es-pollinisateurs en rĂ©gion Euro-MĂ©diterranĂ©enne et montrĂ© que la similaritĂ© de niches de pollinisation entre orchidĂ©es Ă©tait fonction de leur distribution spatio-temporelle, suggĂ©rant un certain opportunisme dans les interactions orchidĂ©es-pollinisateurs. Je me suis ensuite intĂ©ressĂ©e au rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux dans deux groupes dâorchidĂ©es. Jâai dâabord montrĂ© une diffĂ©rentiation dans les traits floraux des trois taxa du groupe Anacamptis coriophora, probablement causĂ©e et maintenue par un processus de sĂ©lection divergente. En cartographiant les interactions avec les pollinisateurs et les odeurs florales sur la phylogĂ©nie de la section Pseudophrys, jâai ensuite montrĂ© que l'Ă©volution de l'odeur florale Ă©tait conditionnĂ©e par une sĂ©lection exercĂ©e par les pollinisateurs et par des contraintes phylogĂ©nĂ©tiques. Enfin, jâai mis au point une dĂ©marche de taxonomie intĂ©grative basĂ©e sur des donnĂ©es molĂ©culaires, morphomĂ©triques et chimiques dans le genre Ophrys. Avec cette dĂ©marche, jâai confirmĂ© le rang taxonomique des trois espĂšces du groupe O. insectifera et proposĂ© de fusionner deux paires dâespĂšces parmi les Pseudophrys. Une meilleure comprĂ©hension des facteurs qui façonnent la niche de pollinisation et du rĂŽle des pollinisateurs dans l'Ă©volution des traits floraux et la spĂ©ciation chez les orchidĂ©es Euro-MĂ©diterranĂ©ennes devrait nous permettre dâamĂ©liorer la conservation de ces espĂšces emblĂ©matiques
Extensive pollinator sharing does not promote character displacement in two orchid congeners
International audienc
Les défis inhérents à la systématique et la taxinomie de genres ayant connu une radiation explosive récente : le cas des orchidées du genre Ophrys
International audienc