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Two types of perigon coloration can be found in the genus Ophrys: ( A ) O. attica exhibits a green perigon, typical for most Ophrys species. In contrast ( B ) O. heldreichii exhibits a bright pinkish perigon, which is frequently found in the O. holoserica - oestrifera group
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Orchids of the genus Ophrys are pollinated by males of solitary bees and wasps through sexual deception. Flowers mimic the odor of a receptive female
and thus attract males that seek to copulate. Visual stimuli have been assumed so far to play only a minor role in male attraction.
We investigated the role of the perigon as a potential visual signal...
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The attraction of male pollinating insects by sexual deception is known for several orchids from the Mediterranean, Australia, South Africa and South America. The sexual delusion may be so enticing in some species that it elicits males to attempt copulation with insect-like structures of the labellum. Pollination by such a pseudocopulation mechanis...
Pterostylis is a diverse genus of terrestrial orchids with dull-coloured trap flowers, of which pollination has largely remained a mystery. Recently, one species has been confirmed to achieve pollination by the sexual deception of male fungus gnats. Here we assess if this pollination mechanism is used more widely in the genus. We ‘baited’ for polli...
Citations
... It should be recalled at this point that Ophrys species are sexual deceptive flowers that attract male bees with species-specific bouquets of scents, thereby encouraging them to attempt mating with the flower and thus enabling suitable pollen transfer to occur (KULLENBERG 1961, SCHIESTL et al. 1999). In the pollination process of the genus Ophrys, these males act as so-called "pragmatic isolation mechanisms" and therefore exert a strong selection on flowering behavior, scent characteristics and, for our assessments in practice, on the appearance, the coloration (PAULUS & GACK 1990, SPAethe et al. 2007RAKOSY et al. 2012;PAULUS 2019) and the size of the labellum of the flowers. The latter is important for Ophrys because successful pollination is only guaranteed when the body size of the male bees and the size of the labellum match. ...
Summary
Hirth, M. & H.F. Paulus (2024): Pollination biology, morphology, taxonomy of
the small flowered species of the Ophrys holosericea aggregate in the East
Aegean.- J. Eur. Orch. 56 (2-4): 219-266.
For many years, we have been visiting several of the East Aegean islands to
study the orchid flora there. For this work, we paid particular attention to the
different populations of the small-flowered Ophrys holosericea group, which
presented themselves differently on each of the islands visited. As smallflowered,
we group together plants of the Ophrys holosericea aggregate with lip
length less than 1 cm. To understand these better and, above all, to be able to
establish their taxonomic-systematic status, we visited the larger islands of
Samos and Kos in particular, as well as the smaller islands of Phournoi, Tilos
and Lipsi. To be able to establish the populations concerned as a biospecies, we
studied the pollination biology in particular. The following results can be
presented.
1. On the island of Samos, we discovered the presence of two different “small
flowered holosericeas”. One in the center, north of the city of Mytilene, with
a substantial population in an extensively used vineyard. The other mainly in
the southwest of the island, in the Limnionas-Agia Kyriaki area. Both forms
differ in flower morphology and have different pollinators. The vineyard
population has already been published in advance in the new field guide by
KREUTZ (2024) under the name Ophrys ampelaki M.Hirth, Paulus, Kreutz. Its
pollinator is the small long-horned bee Eucera digitata. The other form is
Autorenexemplar - copyright by AHO Baden-Württemberg
220 Journal Europäischer Orchideen 56 (2-4): 2024.
described as O. kerkissoula M.Hirth & Paulus in this article. This species also
occurs on the neighbouring island of Phournoi. Its pollinator is Eucera
laxiscopa.
2. From the small island of Lipsoi. a small flowered holosericea is reported but
not finaly discribed, as the data base is insufficient and the pollinator is
unknown.
3. Ophrys tili from the island of Tilos was re-examined and compared with the
very similar-looking plants from Kos which had already been described as
O. ellinicaea Kreutz & B. Tenschert (2011). Since both forms are hardly to
distinguish and both have the same pollinator, Eucera cineraria, we consider
them to be conspecific.
4. In a phylogeographic context, the current distributions of the species are
discussed with regard to data presented by KOUGIOUMOUTZIS et al. (2017) on
pre- and postglacial land changes in the eastern Aegean.
... Es sei an dieser Stelle daran erinnert, dass Ophrys-Arten Sexualtäuschblumen sind, die über artspezifische Duftbouquets Bienenmännchen anlocken, diese dadurch zu Paarungsversuchen mit der Blüte animieren und so zu passenden Pollenübertragungen kommen können (KULLENBERG 1961, SCHIESTL et al. 1999. Diese Männchen fungieren im Bestäubungsgeschehen der Gattung Ophrys als sogenannte "prägame Isolationsmechanismen" und üben daher eine starke Selektion auf Blühverhalten, Duftausstattung und für unsere Beurteilungen in der Praxis auf das Aussehen, der Färbungen (PAULUS & GACK 1990, SPAETHE et al. 2007RAKOSY et al. 2012; PAULUS 2019) und der Lippengrößen der Blüten aus. Letzteres ist bei Ophrys deshalb von Bedeutung, da nur oder doch vor allem bei passender Körpergröße der Bienenmännchen und Labellumgröße eine erfolgreiche Bestäubung gewährleistet ist. ...
changes in the eastern Aegean.
Zusammenfassung
Hirth, M. & H.F. Paulus (2024): Bestäubungsbiologie, Morphologie,
Taxonomie kleinblütiger Sippen des Ophrys holosericea-Aggregates in der OstÄgäis.-
J. Eur. Orch. 56 (2-4): 219-266.
Seit vielen Jahren besuchen wir eine Reihe der ostägäischen Inseln, um die
dortigen Orchideen zu studieren. Besonderes Augenmerk legten wir für diese
Arbeit auf die verschiedenen Populationen der kleinblütigen Arten der Ophrys
holosericea-Gruppe, die sich auf jeder der besuchten Inseln andersartig
darstellten. Unter “kleinblütig“ fassen wir aus eher pragmatischen Gründen
diejenigen Formen zusammen, die eine Lippenlänge von 1 cm und weniger
haben. Um diese besser verstehen zu können und vor allem ihren taxonomischsystematischen
Status begründen und festlegen zu können, besuchten wir vor
allem die größeren Inseln Samos und Kos, daneben auch die kleinen Inseln
Phournoi, Tilos und Lipsi. Um die betreffenden Populationen gegebenenfalls
besser als Biospezies begründen zu können, studierten wir vor allem die
Bestäubungsbiologie. Folgende Ergebnisse können präsentiert werden:
1. Auf der Insel Samos beschäftigten wir uns mit Vorkommen von zwei
verschiedenen Arten der kleinblütigen Hummel-Ragwurz. Eines im Zentrum
nördlich der Stadt Mytilini mit einer stattlichen Population in einem extensiv
genutzten Weinberg. Diese Population wurde unter dem Namen Ophrys
ampelaki M.Hirth, Paulus, Kreutz bereits vorab im neuen Feldführer von
Kreutz (2024) veröffentlicht. Ihr Bestäuber ist die kleine Langhornbiene
Eucera digitata. Eine andere vor allem im Südwesten der Insel im Raum
Limnionas-Agia Kyriaki. Diese Form wird als Ophrys kerkissoula M.Hirth &
Paulus in diesem Artikel neu beschrieben. Die Art kommt auch auf der
Nachbarinsel Phournoi vor. Ihr Bestäuber ist Eucera laxiscopa. Beide Formen
unterscheiden sich in der Blütenmorphologie und haben verschiedene
Autorenexemplar - copyright by AHO Baden-Württemberg
Journal Europäischer Orchideen 56 (2-4): 2024. 221
Bestäuber.
2. Von der kleinen Insel Lipsoi wird eine kleinblütige holosericea gemeldet,
aber nicht abschließend beschrieben, da die Datenbasis unzureichend und der
Bestäuber unbekannt ist.
3. Ophrys tili von der Insel Tilos wurde erneut untersucht und mit den sehr
ähnlich aussehenden Pflanzen von Kos verglichen, die bereits früher als
O. ellinicaea beschrieben wurden. Da beide Formen kaum zu unterscheiden
sind und beide denselben Bestäuber Eucera cineraria haben, halten wir sie
für konspezifisch.
4. In einer phylogeographischen Erörterung werden die heutigen Verbreitungen
der Arten im Zusammenhang der Daten von KOUGIOUMOUTZIS et al. (2017)
der prä- und postglazialen Landveränderungen der östlichen Ägäis diskutiert.
Summary
Hirth, M. & H.F. Paulus (2024): Pollination biology, morphology, taxonomy of
the small flowered species of the Ophrys holosericea aggregate in the East
Aegean.- J. Eur. Orch. 56 (2-4): 219-266.
For many years, we have been visiting several of the East Aegean islands to
study the orchid flora there. For this work, we paid particular attention to the
different populations of the small-flowered Ophrys holosericea group, which
presented themselves differently on each of the islands visited. As smallflowered,
we group together plants of the Ophrys holosericea aggregate with lip
length less than 1 cm. To understand these better and, above all, to be able to
establish their taxonomic-systematic status, we visited the larger islands of
Samos and Kos in particular, as well as the smaller islands of Phournoi, Tilos
and Lipsi. To be able to establish the populations concerned as a biospecies, we
studied the pollination biology in particular. The following results can be
presented.
1. On the island of Samos, we discovered the presence of two different “small
flowered holosericeas”. One in the center, north of the city of Mytilene, with
a substantial population in an extensively used vineyard. The other mainly in
the southwest of the island, in the Limnionas-Agia Kyriaki area. Both forms
differ in flower morphology and have different pollinators. The vineyard
population has already been published in advance in the new field guide by
KREUTZ (2024) under the name Ophrys ampelaki M.Hirth, Paulus, Kreutz. Its
pollinator is the small long-horned bee Eucera digitata. The other form is
Autorenexemplar - copyright by AHO Baden-Württemberg
220 Journal Europäischer Orchideen 56 (2-4): 2024.
described as O. kerkissoula M.Hirth & Paulus in this article. This species also
occurs on the neighbouring island of Phournoi. Its pollinator is Eucera
laxiscopa.
2. From the small island of Lipsoi. a small flowered holosericea is reported but
not finaly discribed, as the data base is insufficient and the pollinator is
unknown.
3. Ophrys tili from the island of Tilos was re-examined and compared with the
very similar-looking plants from Kos which had already been described as
O. ellinicaea Kreutz & B. Tenschert (2011). Since both forms are hardly to
distinguish and both have the same pollinator, Eucera cineraria, we consider
them to be conspecific.
4. In a phylogeographic context, the current distributions of the species are
discussed with regard to data presented by KOUGIOUMOUTZIS et al. (2017) on
pre- and postglacial land changes in the eastern Aegean.
... Given the weakness or non-existence of postmating barriers, these orchids rely on the robust prepollination reproductive isolation provided by their floral scents and labella to prevent hybridisation [23][24][25][26]28]. Besides floral scent-which has a primary significance for both pollinator attraction and reproductive isolation in sexually deceptive orchids-morphological features of the flowers such as shape, colour, size, and texture provide visual and tactile cues to male pollinators, playing a decisive role in effectively turning attraction into pollination [11,16,18,[30][31][32][33][34][35][36][37]. Therefore, characterising the key floral traits involved in the attraction of specific pollinators is crucial to an understanding of the process of pollinator-driven speciation [28,29,[36][37][38][39]. ...
... Consequently, the speculum constitutes a secondary key visual stimulus that, in combination with the primary key odour signal, seems to play a decisive role in the short-range attraction of male insect pollinators to the flower [11,43]. Further field experiments with diverse Ophrys species and their respective insect pollinators are yet needed to demonstrate which labellar features act effectively as visual stimuli for pollinators [30,32,36,37,39]. ...
Pollination by sexual deception specifically attracts male insects, through the floral scent and particular morphological features of the flower that serve as visual and tactile stimuli. The unique bond between the Ophrys speculum orchid and the male Dasyscolia ciliata wasp primarily stems from a few distinctive semiochemicals that mimic the female wasp’s sex pheromone, although the floral scent comprises a variety of compounds. An osmophore producing highly volatile compounds has been documented in four close relatives of O. speculum and is now being also investigated in this species. Given the existing debates regarding the structure of the labellum and stigmatic cavity in O. speculum, this study details their micromorphology. Additionally, comparisons of O. speculum flowers and female D. ciliata wasps under stereomicroscopy and scanning electron microscopy are conducted to seek new evidence of visual and tactile mimicry. The findings confirm that (i) an osmophore is present at the apical margin of the labellum in O. speculum flowers; (ii) the labellum features a distinct basal field homologous to those found in other Ophrys species; and (iii) the basal labellum region closely mimics the female wasp’s thorax and wings. The implications of these novel floral features are discussed within an evolutionary context.
... The profiling of volatile organic compounds in the flowers of A. cuneata will provide probable information for its attraction towards T. macroceps compared to A. nervosa. The floral scent and visual cues synergistically attract Tetralonia bees for pollination (Spaethe et al., 2007). Modifying the key volatile components of flowers would play a vital role in the rate of visitation by a specific pollinator resulting in an enhanced pollination rate and reproductive success of crop plants (Parachnowitsch et al., 2012). ...
Floral specificity is a behavior that evolved due to mutualistic interactions between the plant-pollinator community. Flowers advertise themselves using visual or chemical cues to attract pollinators and gain reproductive success through pollination. Pollinators forage for rewards such as nectar or pollen produced by the flowers. We found that an anthophorid bee, Tetralonia macroceps, foraged specifically on Argyreia cuneata flowers. No visitation was observed on the flowers of A. nervosa though both belong to Convolvulaceae. T. macroceps was the most abundant floral visitor (5.21 bees/flower/5 min) on A. cuneata and did not visit A. nervosa. Mass flowering and narrow tubular flower structure with easy access to pollen in A. cuneata were the traits that accounted for the foraging specificity of T. macroceps. The present study investigates the preference of T. macroceps for the flowers and floral extracts of A. cuneata and A. nervosa. The bee visited 10.16 flowers/5 min of A. cuneata. T. macroceps were highly attracted to the flowers of A. cuneata. No
bees were attracted to A. nervosa. The floral abundance of A. cuneata was relatively higher compared to A. nervosa. Pollen analysis of foraging bees of T. macroceps revealed the selective preference towards the pollen of A. cuneata. The highest number of bees preferred the extract of A. cuneata (7.75) compared to A. nervosa (0.50) in the Y-olfactory maze. Floral extract of A. cuneata caused the highest neuronal electroantennogram (EAG) response (1.48 mV) than A. nervosa (0.36 mV). Our preliminary studies indicated the presence of specific volatile organic compounds (VOCs) nonacosane (13.26%), hexatriacontane (12.06%), and beta farnesene (6.19%) observed in A. cuneata were absent in congener A. nervosa.
... A specific case of interest is that of Xylocopa iris, which has distinctly blue-reflecting wings, similarly as the structurally coloured wings of the related carpenter bee X. latipes (Stavenga et al. 2023). The body pattern of a resting female X. iris with her metallic reflecting wings is mimicked by the orchids Ophrys spuneri and O. sipontensis (Spaethe et al. 2007). Males are attracted by the orchids, and via their subsequent visits, they function in pollinating the orchids. ...
... Nanosized structures, most likely multilayers in the strongly melanized wings as in X. latipes, cause the distinct blue-violet colour of for instance X. valga and X. iris. The short-wavelength reflections presumably have a function in intraspecific communication, as is indicated by orchids that mimic the females (Spaethe et al. 2007). Blue structural colouration is encountered also in other hymenopterans, e.g., the blue-banded bee Amegilla cingulate and the neon cuckoo bee Thereus nitidulus (Saranathan et al. 2015). ...
Carpenter bees can display distinct colouration patterns due to structural coloured wings and/or coloured hairs on their bodies. Females of the sexually dichromatic Xylocopa caerulea are marked by strongly blue-pigmented hairs on the head, thorax and abdomen. The thorax of female X. confusa is covered by yellow-pigmented hairs. The diffuse pigmentary colouration of the blue and yellow hairs is effectively enhanced by strongly scattering granules. The absorption spectrum of the blue pigment of X. caerulea has a maximum at 605 nm and is probably a bilin (a bile pigment). The absorption spectrum of the yellow pigment of X. confusa has a maximum at 445 nm and may be a pterin. The thoracic hairs of female X. confusa contain also a minor amount of the bilin. The reflectance spectra of the pigmented hairs suggest that the pigments are tuned to the spectral sensitivity of the bees' photoreceptors and provide spectral contrast with a green background.
... The most notable exception is the series of behavioural experiments conducted by Hannes Paulus and colleagues using the pink-sepaled microspecies heldreichii (macrospecies Fuciflora) as their experimental system. Initially, Spaethe et al. [101] recorded the effect on pollinator attraction of removing the sepals and lateral petals. When tested using the eucerid bee Tetralonia (Eucera) berlandi, excision reduced the attractiveness of an actual flower by ca. ...
Simple Summary: Our frequently deployed approach to optimally circumscribing species requires large-scale field sampling within and between populations for large numbers of morphometric characters, followed by multivariate ordinations to objectively seek discontinuities (or, failing that, zones of limited overlap) among sets of populations considered to represent species. Corresponding boundaries are sought in DNA-based outputs, either phylogenies or preferably ordinations based on population genetic data. Herein, we analyse within a molecular phylogenetic framework detailed morphometric data for the charismatic bee orchids (Ophrys), seeking a 'mesospecies' species concept that might provide a compromise between the nine 'macrospecies' recognised primarily through DNA barcoding and the several hundred 'microspecies' recognised primarily through perceived pollinator specificity. Our analyses failed to find robust groupings that could be regarded as credible mesospecies, instead implying that each macrospecies constitutes a morphological continuum. This problematic result encouraged us to reappraise both our morphometric approach and the relative merits of the contrasting macrospecies and microspecies concepts, and to reiterate the key role played by genetics in species circumscription. Abstract: Despite (or perhaps because of) intensive multidisciplinary research, opinions on the optimal number of species recognised within the Eurasian orchid genus Ophrys range from nine to at least 400. The lower figure of nine macrospecies is based primarily on seeking small but reliable discontinuities in DNA 'barcode' regions, an approach subsequently reinforced and finessed via high-throughput sequencing studies. The upper figure of ca. 400 microspecies reflects the morphological authoritarianism of traditional taxonomy combined with belief in extreme pollinator specificity caused by reliance on pollination through pseudo-copulation, enacted by bees and wasps. Groupings of microspecies that are less inclusive than macrospecies are termed mesospecies. Herein, we present multivariate morphometric analyses based on 51 characters scored for 457 individual plants that together span the full morphological and molecular diversity within the genus Ophrys, encompassing 113 named microspecies that collectively represent all 29 mesospecies and all nine macrospecies. We critique our preferred morphometric approach of accumulating heterogeneous data and analysing them primarily using principal coordinates, noting that our conclusions would have been strengthened by even greater sampling and the inclusion of data describing pseudo-pheromone cocktails. Morphological variation within Ophrys proved to be exceptionally multidimensional, lacking strong directional trends. Multivariate clustering of plants according to prior taxonomy was typically weak, irrespective of whether it was assessed at the level of macrospecies, mesospecies or microspecies; considerable morphological overlap was evident even between subsets of the molecularly differentiable macrospecies. Characters supporting genuine taxonomic distinctions were often sufficiently subtle that they were masked by greater and more positively correlated variation that reflected strong contrasts in flower size, tepal colour or, less often, plant size. Individual macrospecies appear to represent morphological continua, within which taxonomic divisions are likely to prove arbitrary if based exclusively on morphological criteria and adequately sampled across their geographic range. It remains unclear how much of the mosaic of subtle character variation among the microspecies reflects genetic versus epigenetic or non-genetic influences and what proportion of any contrasts observed in gene frequencies can be attributed to the adaptive microevolution that is widely considered to dictate speciation in the genus. Moreover, supplementing Biology 2023, 12, 136. https://doi.org/10.3390/biology12010136 https://www.mdpi.com/journal/biology Biology 2023, 12, 136 2 of 52 weak morphological criteria with extrinsic criteria, typically by imposing constraints on geographic location and/or supposed pollinator preference, assumes rather than demonstrates the presence of even the weakest of species boundaries. Overall, it is clear that entities in Ophrys below the level of macrospecies have insufficiently structured variation, either phenotypic or genotypic, to be resolved into discrete, self-circumscribing ("natural") entities that can legitimately be equated with species as delimited within other less specialised plant genera. Our search for a non-arbitrary (meso)species concept competent to circumscribe an intermediate number of species has so far proven unsuccessful.
... G Angle dependence of the TE-and TM-signal, elicited by sunlight (inset) reflected by the wing, in a UV-, B-, and G-photoreceptor, with absorption spectrum as in inset panel H. H Polarization degree of the sunlight reflected by the wing and absorbed by the three receptor types as a function of the angle of light incidence The role of the body colouration is far from well understood, but indirect evidence can be derived from the case of Xylocopa iris. The reflecting wings of the females when at rest display a distinct pattern that mimics the orchids Ophrys spuneri and O. sipontensis (Spaethe et al. 2007). Males attracted by this pattern land sequentially on different orchids and thus fulfil a pollinating function. ...
The tropical carpenter bee, Xylocopa latipes, has metallic-reflecting, iridescent wings. The wing reflectance spectra for TE- and TM-polarized light depend on the angle of light incidence in a way characteristic for dielectric multilayers. Anatomy indicates the presence of melanin multilayers in the wing’s chitinous matrix. A simple optical model of melanin multilayers explains the angle dependence of the wing reflectance spectra. The wing reflections that occur upon oblique illumination exhibit colourful and strongly polarized light patterns, which may mediate intraspecific signaling and mutual recognition by conspecifics.
... Different authors [76][77][78] have demonstrated that the Ophrys flower mimics the chemical compounds exactly like those produced by the true females of the pollinating males. Olfaction is used to orientate from a distance; however, in the near vicinity, where spatial vision is sufficient to detect the flower, the males' approach is only visually guided [79,80]. Thus, to further ensure success, the pollinating males also select other characters of the Ophrys flower such as labellum size, colour, labellum hair characters, phenology and possibly habitat selections, etc. [58]. ...
In central western Spain, the bee orchid Ophrys scolopax Cav. is limited to a few localities of the Arribes del Duero Natural Park, reaching the municipality of Villarino de los Aires (Salamanca) to the north. Due to its restricted distribution, this plant is hardly known in this territory, with the exception of this village, where it is very popular. Although most of its inhabitants are unaware of various aspects of the biology of this orchid, for example its pollination strategy, the place where the only local population grows is well-known: the Teso de San Cristóbal (“St. Christopher’s Hill”), a place of ancient pagan rituals Christianised through the construction of a hermitage. The villagers also know that its flowering period coincides with the Easter celebration, and they have traditionally looked for and collected it there during Easter Monday. This ritual has evolved over time based on the needs and interests of the community. From a religious celebration aimed at blessing the fields, it became a game among young men to obtain prestige within the community, and from the end of the 20th century to the present, it has become a festival to revitalise cultural identity. In this article, we analyse how the aforementioned traditional practices affected this orchid species in the recent past, and we describe the educational actions (conferences, workshops, courses, etc.) carried out during the last ten years so that, while maintaining the cultural practices of the village, its population should be respected and conserved at the same time.
... Thus, in typically fly (or rarely bee, wasp) pollinated species of this pantropical genus (about 2400 spp.; Sieder et al. 2009), the pollinator usually moves along the hinged and motile labellum and is forced against the column for pollinia deposition or removal (e.g., Chen and Gao 2011;Chen et al. 2014;Ong and Tam 2019;Hu et al. 2020; see Fig. 1 for details). Hence, at least for this genus, the efficiency hypothesis of modularity would predict that labellum and column together form a distinct unit that evolved separately from both sepals and the remaining petals, which are likely to act primarily as visual attractants (Spaethe et al. 2007;Rakosy et al. 2012;Kowalkowska et al. 2015Kowalkowska et al. , 2017Dodson 2020; but see Hu et al. 2020). ...
Covarying suites of phenotypic traits, or modules, are increasingly recognized to promote morphological evolution. However, information on how modularity influences flower diversity is rare and lacking for Orchidaceae. Here we combine high‐resolution X‐ray computed tomography scanning with 3D geometric morphometrics and phylogenetic comparative methods to test various hypotheses about three‐dimensional patterns of flower evolutionary modularity in Malagasy Bulbophyllum orchids and examine rates and modes of module evolution. Based on the four evolutionary modules identified (i.e., sepals, lateral petals, labellum + column‐foot, and column‐part), our data support the hypothesis that both genetic‐developmental and functional adaptive factors shaped evolutionary flower trait covariation in these tropical orchids. In line with ‘evo‐devo’ studies, we also find that the labellum evolved independently from the rest of the petal whorl. Finally, we show that modules evolved with different rates, and either in a neutral fashion (only column‐part) or under selective constraints, as likely imposed by pollinators. Overall, this study supports current views that modular units can enhance the range and rate of morphological evolution. This article is protected by copyright. All rights reserved
... The astonishing precision by which pollen is placed on a pollinator's body during visits to zygomorphic flowers is exemplified by some species of orchids, in which flower shapes are so complex that they include highly specialised structures which only specific types of pollinators (insects and sometimes vertebrates) can access to feed, while passively supporting plant reproduction [21]. An extreme example of the complexity of bilateral flowers is the orchid genus Ophrys which produce blossoms that mimic the form and scent of a female wasp to attract/ deceive male wasps in search of a mating partner ( Figure 2) [22,23]. Although the mutual benefit for both plants and animals is clear, the debate of who led this co-evolution, e.g. ...
The flower is an astonishing innovation that arose during plant evolution allowing flowering plants — also known as angiosperms — to dominate life on earth in a relatively short period of geological time. Flowers are formed from secondary meristems by co-ordinated differentiation of flower organs, such as sepals, petals, stamens, and carpels. The position, number and morphology of these flower organs impose a geometrical pattern — or symmetry type — within the flower which is a trait tightly connected to successful reproduction.
During evolution, flower symmetry switched from the ancestral poly-symmetric (radial symmetry) to the mono-symmetric (bilateral symmetry) type multiple times, including numerous reversals, with these events linked to co-evolution with pollinators and reproductive strategies.
In this review, we introduce the diversity of flower symmetry, trace its evolution in angiosperms, and highlight the conserved genetic basis underpinning symmetry control in flowers. Finally, we discuss the importance of building upon the concept of flower symmetry by looking at the mechanisms orchestrating symmetry within individual flower organs and summarise the current scenario on symmetry patterning of the female reproductive organ, the gynoecium, the ultimate flower structure presiding over fertilisation and seed production.