G.I.R.O.S. - Gruppo Italiano per la Ricerca sulle Orchidee Spontanee

Solo il fiore che lasci sulla pianta è tuo. (Aldo Capitini)
Oggi è 17 gennaio 2022, 3:04

Tutti gli orari sono UTC +1 ora [ ora legale ]




Apri un nuovo argomento Rispondi all’argomento  [ 2 messaggi ] 
Autore Messaggio
 Oggetto del messaggio: Nuovi studi sui morfotipi bianchi
MessaggioInviato: 5 dicembre 2013, 14:22 
Non connesso
Amministratore
Avatar utente

Iscritto il: 29 maggio 2011, 16:05
Messaggi: 1646
Nome: Luca
Cognome: Oddone
Località: Mongardino (AT)
Vi segnalo due articoli, uno pubblicato pochi giorni fa e disponibile online, che studiano in modo approfondito la presenza e la funzione delle piante a morfotipo bianco nelle popolazioni di orchidee, in particolare per la Orchis mascula.



Bertrand Schatz, Roxane Delle-Vedove, Laurent Dormont, 2013
Presence, distribution and effect of white, pink and purple morphs on pollination in the orchid Orchis mascula

Abstract.
How floral polymorphism of flowering plants can be maintained in evolutionary time has long intrigued ecologists and is still debated. In particular, how floral colour polymorphism influences reproductive success is still poorly understood. Here, we investigated the case of Orchis mascula, a deceptive orchid species in which the presence of rare white-flowered individuals is known to increase the percentage pollination of co-occurring coloured morphs. In a brief review, we report all the orchid species for which rare colour morphs are recorded and show that colour polymorphism occurs in most orchid genera occurring in France. In this study, more than 20,000 individuals of O. mascula were surveyed and some rare clear pink morphs were recorded. The frequencies of white-flowered and clear pink-flowered individuals were 0.59% and 0.28%, respectively. These two rare-colour flowered individuals were not randomly distributed and restricted to a few populations. In addition, the presence of pink-flowered individuals and the use of experimental pink lures resulted in an increase in the percentage pollination of surrounding purple-flowered individuals, as previously shown for white-flowered individuals and white lures. These new observations favour kin selection as the means by which floral colour polymorphism is maintained in this species. We suggest conducting comparative studies of other species in order to evaluate the importance of this mechanism in orchid pollination and that of other plant families.

PDF disponibile online





Dormont L, Delle-Vedove R, Bessière JM, Hossaert-Mc Key M, Schatz B., 2010:
Rare white-flowered morphs increase the reproductive success of common purple morphs in a food-deceptive orchid.

Abstract.
How floral colour polymorphism can be maintained in evolutionary time is still debated. In rewardless orchids, it is unknown whether rare white-flowered morphs differ in scent chemistry from pigmented morphs, and whether such intraspecific variation in floral signals may have an impact on reproductive success. We compared the chemical composition of floral volatiles emitted by white- and purple-flowered morphs of Orchis mascula, and recorded the fruit set of both colour morphs. We also used white ping-pong balls to mimic white-flowered morphs in field bioassays. We found that colour polymorphism was not associated with floral odour polymorphism. Surprisingly, when populations of purple-flowered plants included a few white-flowered individuals, the fruit set of the purple morph increased significantly (from 6 to 27%), while that of the white morph remained low. We obtained the same fourfold increase in fruit set when using ping-pong balls as visual lures, demonstrating the association between colour variation and fruit set, and the key role of visual signals in pollinator attraction. Our results are incompatible with negative frequency-dependent selection, a hypothesis invoked to explain colour polymorphism in other rewardless orchids. We propose several hypotheses to explain the maintenance of white morphs in O. mascula.

_________________
:ciaoo:
Luca

«Nomina si nescis, perit et cognito rerum» - Se si ignora il nome delle cose, se ne perde anche la conoscenza. C. Linnaeus, Philosophia botanica (1751)

«I was much struck how entirely vague and arbitrary is the distinction between species and varieties. Charles Darwin, On the Origin of Species (1859)

«This disagreement regarding bee orchid diversity represents a particularly extreme example of a phenomenon that frequently afflicts taxonomy - a dichotomy between researchers who divide natural variation into as many units as possible (splitters) and others who aggregate those subtly different units into entities that they consider to be either more easily recognised or more biologically meaningful (lumpers)» - R.M. Bateman

«Un fiore, anche il più insignificante, è la mirabile risultanza di un collaudato progetto genomico, di precisi equilibri ecologici, dell'azione congiunta del sole, del terreno, della pioggia e della rugiada, del vento e degli insetti impollinatori. Quale unica specie consapevole della complessità di questi processi e della preziosità del risultante dono, è nostro dovere promuoverne la conoscenza e prodigarci per la sua protezione» - G. Sciarretta


Immagine

Nomenclatura GIROS - Biodiversity Heritage Library - IPNI, International Plant Names Index - Kew Gardens Checklist



Top
 Profilo  
 
 Oggetto del messaggio: Re: Nuovi studi sui morfotipi bianchi
MessaggioInviato: 16 febbraio 2014, 11:27 
Non connesso
Amministratore
Avatar utente

Iscritto il: 29 maggio 2011, 16:05
Messaggi: 1646
Nome: Luca
Cognome: Oddone
Località: Mongardino (AT)
Ecco un altro articolo, recentissimo, sui morfotipi bianchi... in questo caso vengono studiate e confrontate le molecole emesse da Orchis mascula, Orchis simia e Anacamptis coriophora fragrans, morfotipo a colorazione normale e morfotipo bianco.

L. Dormont, R. Delle-Vedovea, J.-M. Bessièreb, B. Schatz, 2014 - Floral scent emitted by white and coloured morphs in orchids.
Phytochemistry, Available online 10 February 2014 - http://dx.doi.org/10.1016/j.phytochem.2014.01.009


Highlights

• Floral volatiles emitted by white- and coloured orchid morphs are compared.
• Overall floral scent does not differ between morphs in two orchid species.
• Only Orchis simia exhibits different odours between white and purple morphs.
• White inflorescences emit more benzenoids than purple morph in two species.
• The two deceptive orchids show higher variation of floral scent.


Abstract

Polymorphism of floral signals, such as colour and odour, is widespread in flowering plants and often considered to be adaptive, reflecting various pollinator preferences for particular floral traits. Several authors have recently hypothesized that particular associations exist between floral colour and scent, which would result from shared biochemistry between these two floral traits. In this study, we compared the chemical composition of floral volatiles emitted by white- and purple-flowered morphs of three different orchid species, including two food-deceptive species (Orchis mascula and Orchis simia) and a food-rewarding species (Anacamptis coriophora fragrans). We found clear interspecific differences in floral odours. As expected from their pollination strategy, the two deceptive orchids showed high inter-individual variation of floral volatiles, whereas the food-rewarding A. c. fragrans showed low variation of floral scent. Floral volatiles did not differ overall between white- and coloured-flowered morphs in O. mascula and A. c. fragrans, while O. simia exhibited different volatile profiles between the two colour morphs. However, a detailed analysis restricted to benzenoid compounds (which are associated with the production of floral anthocyanin pigments) showed that white inflorescences emitted more volatiles of the shikimic pathway than coloured ones, both for O. mascula and O. simia. These results are consistent with the current hypothesis that shared biochemistry creates pleiotropic links between floral colour and scent. Whether intraspecific variation of floral signals actually affects pollinator attraction and influences the reproductive success of these orchids remains to be determined.


Graphical abstract

Floral volatiles emitted by white- and coloured-flowered morphs of Orchis mascula, Orchis simia, and Anacamptis coriophora fragrans were not different between white and coloured morphs, except for O. simia.

_________________
:ciaoo:
Luca

«Nomina si nescis, perit et cognito rerum» - Se si ignora il nome delle cose, se ne perde anche la conoscenza. C. Linnaeus, Philosophia botanica (1751)

«I was much struck how entirely vague and arbitrary is the distinction between species and varieties. Charles Darwin, On the Origin of Species (1859)

«This disagreement regarding bee orchid diversity represents a particularly extreme example of a phenomenon that frequently afflicts taxonomy - a dichotomy between researchers who divide natural variation into as many units as possible (splitters) and others who aggregate those subtly different units into entities that they consider to be either more easily recognised or more biologically meaningful (lumpers)» - R.M. Bateman

«Un fiore, anche il più insignificante, è la mirabile risultanza di un collaudato progetto genomico, di precisi equilibri ecologici, dell'azione congiunta del sole, del terreno, della pioggia e della rugiada, del vento e degli insetti impollinatori. Quale unica specie consapevole della complessità di questi processi e della preziosità del risultante dono, è nostro dovere promuoverne la conoscenza e prodigarci per la sua protezione» - G. Sciarretta


Immagine

Nomenclatura GIROS - Biodiversity Heritage Library - IPNI, International Plant Names Index - Kew Gardens Checklist



Top
 Profilo  
 
Visualizza ultimi messaggi:  Ordina per  
Apri un nuovo argomento Rispondi all’argomento  [ 2 messaggi ] 

Tutti gli orari sono UTC +1 ora [ ora legale ]


Chi c’è in linea

Visitano il forum: Nessuno e 2 ospiti


Non puoi aprire nuovi argomenti
Non puoi rispondere negli argomenti
Non puoi modificare i tuoi messaggi
Non puoi cancellare i tuoi messaggi
Non puoi inviare allegati

Cerca per:
Vai a:  
cron
POWERED_BY
Traduzione Italiana phpBB.it