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Duffy KJ, Scopece G, Cozzolino S, Fay MF, Smith RJ, Stout JC. Ecology and genetic diversity of the dense-flowered orchid, Neotinea maculata, at the centre and edge of its range. ANNALS OF BOTANY 2009; 104:507-16. [PMID: 18940852 PMCID: PMC2720646 DOI: 10.1093/aob/mcn200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 06/06/2008] [Accepted: 08/21/2008] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Species may occur over a wide geographical range within which populations can display large variation in reproductive success and genetic diversity. Neotinea maculata is a rare orchid of conservation concern at the edge of its range in Ireland, where it occurs in small populations. However, it is relatively common throughout the Mediterranean region. Here, factors that affect rarity of N. maculata in Ireland are investigated by comparing Irish populations with those found in Italy, where it is more common. METHODS Vegetation communities, breeding system and genetic diversity were compared using three amplified fragment length polymorphism (AFLP) primer pairs in populations in Ireland and Italy. Vegetation was quantified using quadrats taken along transects in study populations, and hand pollination experiments were performed to assess reliance of N. maculata on pollinators in both Irish and Italian populations. KEY RESULTS Neotinea maculata occupies different vegetation communities in Italian and Irish populations. Breeding system experiments show that N. maculata is 100 % autogamous, and there are no differences in fruit and seed production in selfed, outcrossed and unmanipulated plants. AFLP markers revealed that Irish and Italian populations have similar genetic diversity and are distinct from each other. CONCLUSIONS Neotinea maculata does not suffer any negative effects of autogamous reproduction; it self-pollinates and sets seed readily in the absence of pollinators. It occupies a variety of habitats in both Ireland and Italy; however, Irish populations are small and rare and should be conserved. This could be due to climatic factors and the absence of suitable soil mycorrhizas to allow recruitment from seed.
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Affiliation(s)
- Karl J Duffy
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland.
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202
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Cheng J, Shi J, Shangguan FZ, Dafni A, Deng ZH, Luo YB. The pollination of a self-incompatible, food-mimic orchid, Coelogyne fimbriata (Orchidaceae), by female Vespula wasps. ANNALS OF BOTANY 2009; 104:565-71. [PMID: 19218578 PMCID: PMC2720650 DOI: 10.1093/aob/mcp029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
BACKGROUND AND AIMS The study of specialized interactions between species is crucial to our understanding of processes in evolutionary ecology due to their profound effect on life cycles and diversification. Obligate pollination by a single wasp species is rare in Orchidaceae except in species with sexually deceptive flowers that are pollinated exclusively by male insects. The object of this study was to document pollination of the food-deceptive flowers of Coelogyne fimbriata, a species pollinated exclusively by female wasps. METHODS Field observations and experiments were conducted in two populations of C. fimbriata. Floral phenology was recorded, and functional floral architecture was measured. Insect visitors to flowers were observed from 2005 to 2007. Bioassay experiments were conducted to check whether the floral odour attracted pollinators. Natural (insect-mediated) rates of pollinarium removal, pollinium deposition on stigmas, and fruit set were recorded. To determine the importance of cross-pollination, the breeding system was assessed via controlled, hand-pollination experiments. KEY RESULTS Two populations of C. fimbriata with fragrant, nectarless flowers are pollinated by females of the same Vespula species (Vespidae, Hymenoptera). Experiments on wasps show that they crawl towards the source of the odour. The flowering period appears to coincide with an annual peak in Vespula colony expansion when additional workers forage for carbohydrates. Rates of pollinarium removal (0.069-0.918) and pollinium deposition on stigmas (0.025-0.695) are extremely variable. However, fruit set in C. fimbriata is always low (0.014-0.069) and appears to be based on self-incompatibility coupled with intraclonal (geitonogamous) deposition of pollinia. CONCLUSIONS Coelogyne fimbriata and Steveniella satyrioides are now the only orchid species known to have food-deceptive flowers that are pollinated exclusively by eusocial, worker wasps. In C. fimbriata, floral odour appears to be the major attractant. Sub-populations may go through flowering seasons when pollinators are abundant or infrequent, but fruit set always remains low because the obligate pollinator does not often appear to transfer pollinaria between intercompatible genets.
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Affiliation(s)
- Jin Cheng
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- Graduate School, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jun Shi
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- Graduate School, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fa-Zhi Shangguan
- College of Biology, Guizhou University, Guiyang 500251, People's Republic of China
| | - Amots Dafni
- Laboratory of Pollination Ecology, Institute of Evolution, Haifa University, Haifa, Israel
| | - Zhen-Hai Deng
- Yachang Orchids Nature Reserve, Leye 533209, People's Republic of China
| | - Yi-Bo Luo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- For correspondence. E-mail
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203
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Swarts ND, Dixon KW. Terrestrial orchid conservation in the age of extinction. ANNALS OF BOTANY 2009; 104:543-56. [PMID: 19218582 PMCID: PMC2720663 DOI: 10.1093/aob/mcp025] [Citation(s) in RCA: 222] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/13/2008] [Accepted: 12/22/2008] [Indexed: 05/03/2023]
Abstract
BACKGROUND Conservation through reserves alone is now considered unlikely to achieve protection of plant species necessary to mitigate direct losses of habitat and the pervasive impact of global climate change. Assisted translocation/migration represent new challenges in the face of climate change; species, particularly orchids, will need artificial assistance to migrate from hostile environments, across ecological barriers (alienated lands such as farmlands and built infrastructure) to new climatically buffered sites. The technology and science to underpin assisted migration concepts are in their infancy for plants in general, and orchids, with their high degree of rarity, represent a particularly challenging group for which these principles need to be developed. It is likely that orchids, more than any other plant family, will be in the front-line of species to suffer large-scale extinction events as a result of climate change. SCOPE The South West Australian Floristic Region (SWAFR) is the only global biodiversity hotspot in Australia and represents an ideal test-bed for development of orchid conservation principles. Orchids comprise 6 % of all threatened vascular plants in the SWAFR, with 76 out of the 407 species known for the region having a high level of conservation risk. The situation in the SWAFR is a portent of the global crisis in terrestrial orchid conservation, and it is a region where innovative conservation solutions will be required if the impending wave of extinction is to be averted. Major threatening processes are varied, and include land clearance, salinity, burning, weed encroachment, disease and pests. This is compounded by highly specialized pollinators (locally endemic native invertebrates) and, in the most threatened groups such as hammer orchids (Drakaea) and spider orchids (Caladenia), high levels of mycorrhizal specialization. Management and development of effective conservation strategies for SWAFR orchids require a wide range of integrated scientific approaches to mitigate impacts that directly influence ecological traits critical for survival. CONCLUSIONS In response to threats to orchid species, integrated conservation approaches have been adopted (including ex situ and translocation principles) in the SWAFR with the result that a significant, multidisciplinary approach is under development to facilitate conservation of some of the most threatened taxa and build expertise to carry out assisted migration to new sites. Here the past two decades of orchid conservation research in the SWAFR and the role of research-based approaches for managing effective orchid conservation in a global biodiversity hotspot are reviewed.
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Affiliation(s)
- Nigel D Swarts
- Kings Park and Botanic Garden, West Perth, WA 6005, Australia.
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204
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Cortis P, Vereecken NJ, Schiestl FP, Barone Lumaga MR, Scrugli A, Cozzolino S. Pollinator convergence and the nature of species' boundaries in sympatric Sardinian Ophrys (Orchidaceae). ANNALS OF BOTANY 2009; 104:497-506. [PMID: 19001428 PMCID: PMC2720645 DOI: 10.1093/aob/mcn219] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/01/2008] [Accepted: 09/30/2008] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS In the sexually deceptive Ophrys genus, species isolation is generally considered ethological and occurs via different, specific pollinators, but there are cases in which Ophrys species can share a common pollinator and differ in pollen placement on the body of the insect. In that condition, species are expected to be reproductively isolated through a pre-mating mechanical barrier. Here, the relative contribution of pre- vs. post-mating barriers to gene flow among two Ophrys species that share a common pollinator and can occur in sympatry is studied. METHODS A natural hybrid zone on Sardinia between O. iricolor and O. incubacea, sharing Andrena morio as pollinator, was investigated by analysing floral traits involved in pollinator attraction as odour extracts both for non-active and active compounds and for labellum morphology. The genetic architecture of the hybrid zone was also estimated with amplified fragment length polymorphism (AFLP) markers, and pollination fitness and seed set of both parental species and their hybrids in the sympatric zone were estimated by controlled crosses. KEY RESULTS Although hybrids were intermediate between parental species in labellum morphology and non-active odour compounds, both parental species and hybrids produced a similar odour bouquet for active compounds. However, hybrids produced significantly lower fruit and seed set than parental species, and the genetic architecture of the hybrid zone suggests that they were mostly first-generation hybrids. CONCLUSIONS The two parental species hybridize in sympatry as a consequence of pollinator overlap and weak mechanical isolation, but post-zygotic barriers reduce hybrid frequency and fitness, and prevent extensive introgression. These results highlight a significant contribution of late post-mating barriers, such as chromosomal divergence, for maintaining reproductive isolation, in an orchid group for which pre-mating barriers are often considered predominant.
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Affiliation(s)
- P. Cortis
- Dipartimento di Scienze Botaniche, Università degli Studi di Cagliari, Viale S. Ignazio 13, I-09123 Cagliari, Italy
| | - N. J. Vereecken
- Behavioural and Evolutionary Ecology, Free University of Brussels CP 160/12, Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - F. P. Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - M. R. Barone Lumaga
- Dipartimento di Biologia Strutturale e Funzionale and Orto Botanico, Università di Napoli Federico II, I-80126 Napoli, Italy
| | - A. Scrugli
- Dipartimento di Scienze Botaniche, Università degli Studi di Cagliari, Viale S. Ignazio 13, I-09123 Cagliari, Italy
| | - S. Cozzolino
- Dipartimento di Biologia Strutturale e Funzionale and Orto Botanico, Università di Napoli Federico II, I-80126 Napoli, Italy
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205
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Mondragón-Palomino M, Theissen G. Why are orchid flowers so diverse? Reduction of evolutionary constraints by paralogues of class B floral homeotic genes. ANNALS OF BOTANY 2009; 104:583-94. [PMID: 19141602 PMCID: PMC2720651 DOI: 10.1093/aob/mcn258] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 07/29/2008] [Accepted: 11/17/2008] [Indexed: 05/18/2023]
Abstract
BACKGROUND The nearly 30 000 species of orchids produce flowers of unprecedented diversity. However, whether specific genetic mechanisms contributed to this diversity is a neglected topic and remains speculative. We recently published a theory, the 'orchid code', maintaining that the identity of the different perianth organs is specified by the combinatorial interaction of four DEF-like MADS-box genes with other floral homeotic genes. SCOPE Here the developmental and evolutionary implications of our theory are explored. Specifically, it is shown that all frequent floral terata, including all peloric types, can be explained by monogenic gain- or-loss-of-function mutants, changing either expression of a DEF-like or CYC-like gene. Supposed dominance or recessiveness of mutant alleles is correlated with the frequency of terata in both cultivation and nature. Our findings suggest that changes in DEF- and CYC-like genes not only underlie terata but also the natural diversity of orchid species. We argue, however, that true changes in organ identity are rare events in the evolution of orchid flowers, even though we review some likely cases. CONCLUSIONS The four DEF paralogues shaped floral diversity in orchids in a dramatic way by modularizing the floral perianth based on a complex series of sub- and neo-functionalization events. These genes may have eliminated constraints, so that different kinds of perianth organs could then evolve individually and thus often in dramatically different ways in response to selection by pollinators or by genetic drift. We therefore argue that floral diversity in orchids may be the result of an unprecedented developmental genetic predisposition that originated early in orchid evolution.
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206
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The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products. Proc Natl Acad Sci U S A 2009; 106:8877-82. [PMID: 19470640 DOI: 10.1073/pnas.0900646106] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Orchids employing sexual deceit attract males of their pollinator species through specific volatile signals that mimic female-released sex pheromones. One of these signals proved to be 2-ethyl-5-propylcyclohexan-1,3-dione (chiloglottone1), a new natural product that was shown to be most important in the relations between orchids of the genus Chiloglottis, native to Australia, and corresponding pollinator species. Systematic investigations on the mass spectrometric fragmentation pattern of 2,5-dialkylcyclohexan-1,3-diones identified key ions providing information about the structures of the substituents at positions 2 and 5. Results enabled us to identify 2-ethyl-5-pentylcyclohexan-1,3-dione (chiloglottone2) and 2-butyl-5-methylcyclohexan-1,3-dione (chiloglottone3) as new natural products that play a decisive role in the pollination syndrome of some Chiloglottis species. During field bioassays, pure synthetic samples of chiloglottone1-3 or mixtures thereof proved to be attractive to the corresponding orchid pollinators. Because of their likely biogenesis from ubiquitous fatty acid precursors, 2,5-dialkylcyclohexan-1,3-diones may represent a hitherto overlooked, widespread class of natural products.
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207
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Vandewoestijne S, Róis AS, Caperta A, Baguette M, Tyteca D. Effects of individual and population parameters on reproductive success in three sexually deceptive orchid species. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11:454-63. [PMID: 19470116 DOI: 10.1111/j.1438-8677.2008.00125.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Reproductive success (RS) in orchids in general, and in non-rewarding species specifically, is extremely low. RS is pollinator and pollination limited in food deceptive orchids, but this has rarely been studied in sexually deceptive orchid species. Here, we tested the effects of several individual (plant height, inflorescence size, nearest neighbour distance and flower position) and population (patch geometry, population density and size) parameters on RS in three sexually deceptive Ophrys (Orchidaceae) species. Inter-specific differences were observed in RS of flowers situated in the upper versus the lower part of the inflorescence, likely due to species-specific pollinator behaviour. For all three species examined, RS increased with increasing plant height, inflorescence size and nearest neighbour distance. RS generally increased with decreasing population density and increasing patch elongation. Given these results, we postulate that pollinator availability, rather than pollinator learning, is the most limiting factor in successful reproduction for sexually deceptive orchids. Our results also suggest that olfactory 'display' (i.e. versus optical display), in terms of inflorescence size (and co-varying plant height), plays a key role in individual RS of sexually deceptive orchids. In this regard, several hypotheses are suggested and discussed.
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Affiliation(s)
- S Vandewoestijne
- Biodiversity Research Centre, Université catholique de Louvain, Louvain-la-Neuve, Belgium
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208
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Scopece G, Musacchio A, Widmer A, Cozzolino S. Contrasting thoughts about deceptive orchids: a response to Sobel and Randle. Evolution 2009; 63:2205-9. [PMID: 19453735 DOI: 10.1111/j.1558-5646.2009.00693.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Sobel and Randle (2009) challenge several methodological choices in the comparative study of the evolution of reproductive isolation in Mediterranean deceptive orchids of Scopece et al. (2007) including the species concept used and the selection of taxa, together with the perceived comparison of clades of different ages. They further criticize that pollinator information was taken from the literature and that two different methods were used to estimate pollinator specificity in food-deceptive and sexually deceptive orchids, respectively. Here we reply to these challenges.
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Affiliation(s)
- Giovanni Scopece
- Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli Federico II, Complesso Universitario MSA, Naples, Italy.
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209
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Ebert D, Peakall R. Chloroplast simple sequence repeats (cpSSRs): technical resources and recommendations for expanding cpSSR discovery and applications to a wide array of plant species. Mol Ecol Resour 2009; 9:673-90. [PMID: 21564725 DOI: 10.1111/j.1755-0998.2008.02319.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chloroplast microsatellites, or simple sequence repeats (cpSSRs), are typically mononucleotide tandem repeats. When located in the noncoding regions of the chloroplast genome (cpDNA), they commonly show intraspecific variation in repeat number. Despite the growing number of studies applying cpSSRs, studies of economically important plants and their relatives remain over-represented. Thus, the potential of cpSSRs to offer unique insights into ecological and evolutionary processes in wild plant species has yet to be fully realized. This review provides an overview of the technical resources available to aid cpSSR discovery including a list of cpSSR primer sets available and cpDNA sequencing resources. Our updated analysis of 99 whole chloroplast genomes downloaded from GenBank confirms that potentially variable cpSSRs are abundant in the noncoding cpDNA of plants. Overall variation in the frequency of cpSSRs was extreme, ranging from one to 700 per genome (median = 93), while in 81 vascular plants, between 35 and 160 cpSSRs were detected per genome (median = 86). We offer five recommendations to aid wider development and application of cpSSRs: (i) When genus-specific cpSSR primers are available, cross-species amplification can often be fruitful. (ii) While potentially useful, universal cpSSR primers at best provide access to only a small number of variable markers. (iii) De novo sequencing of noncoding cpDNA is the most effective and efficient way to develop cpSSR markers in wild species. (iv) DNA sequencing of cpSSR alleles is essential, given the complex nature of the genetic variation associated with hypervariable cpDNA regions. (v) The reliability of cpSSR length based genetic assays need to be validated in all studies.
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Affiliation(s)
- Daniel Ebert
- School of Botany and Zoology, The Australian National University, Canberra ACT 0200, Australia
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210
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Schiestl FP, Schlüter PM. Floral isolation, specialized pollination, and pollinator behavior in orchids. ANNUAL REVIEW OF ENTOMOLOGY 2009; 54:425-46. [PMID: 19067636 DOI: 10.1146/annurev.ento.54.110807.090603] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Floral isolation is a form of prepollination reproductive isolation mediated by floral morphology (morphological isolation) and pollinator behavior (ethological isolation). Here we review mechanisms and evolutionary consequences of floral isolation in various pollination systems. Furthermore, we compare key features of floral isolation, i.e., pollinator sharing and specialization in pollination, in different orchid pollination systems. In orchid pollination, pollinator sharing is generally low, indicating strong floral isolation. The pollinators' motivation to visit flowers (specifically) can be due to both foraging or reproductive behavior. In both types of behavior, innate preferences for floral signals can be quickly overruled by learning. In pollination systems in which reproductive behavior of pollinators triggers flower visits, lower pollinator sharing was evident compared with systems with foraging behavior, probably because pollinators displaying reproductive behavior show higher fidelity in their visitation patterns. Orchids pollinated through reproductive behavior also use fewer pollinators than orchids pollinated through foraging behavior. No association between specialization and pollinator sharing was found. Thus, generalized pollination does not impede floral isolation, as orchids with many pollinators may nonetheless have low pollinator sharing. Specialization in pollination was, however, linked to orchid species richness in our analysis. Flower size, spur, and column morphology are most important for morphological isolation, and floral scent is most important for ethological isolation. These traits may be based on few genes, implying that floral isolation can be brought about by few genes of large effect.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, 8008 Zürich, Switzerland.
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211
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Cozzolino S, Scopece G. Review. Specificity in pollination and consequences for postmating reproductive isolation in deceptive Mediterranean orchids. Philos Trans R Soc Lond B Biol Sci 2008; 363:3037-46. [PMID: 18579475 PMCID: PMC2607316 DOI: 10.1098/rstb.2008.0079] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The type of reproductive isolation prevalent in the initial stages of species divergence can affect the nature and rate of emergence of additional reproductive barriers that subsequently strengthen isolation between species. Different groups of Mediterranean deceptive orchids are characterized by different levels of pollinator specificity. Whereas food-deceptive orchid species show weak pollinator specificity, the sexually deceptive Ophrys species display a more specialized pollination strategy. Comparative analyses reveal that orchids with high pollinator specificity mostly rely on premating reproductive barriers and have very little postmating isolation. In this group, a shift to a novel pollinator achieved by modifying the odour bouquet may represent the main isolation mechanism involved in speciation. By contrast, orchids with weak premating isolation, such as generalized food-deceptive orchids, show strong evidence for intrinsic postmating reproductive barriers, particularly for late-acting postzygotic barriers such as hybrid sterility. In such species, chromosomal differences may have played a key role in species isolation, although strong postmating-prezygotic isolation has also evolved in these orchids. Molecular analyses of hybrid zones indicate that the types and strength of reproductive barriers in deceptive orchids with contrasting premating isolation mechanisms directly affect the rate and evolutionary consequences of hybridization and the nature of species differentiation.
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Affiliation(s)
- Salvatore Cozzolino
- Dipartimento delle Scienze Biologiche, Università degli Studi di Napoli Federico II, Via Foria 223, 80139 Naples, Italy.
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212
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Affiliation(s)
- Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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213
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On the scent of speciation: the chemosensory system and its role in premating isolation. Heredity (Edinb) 2008; 102:77-97. [PMID: 18685572 DOI: 10.1038/hdy.2008.55] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Chemosensory speciation is characterized by the evolution of barriers to genetic exchange that involve chemosensory systems and chemical signals. Here, we review some representative studies documenting chemosensory speciation in an attempt to evaluate the importance and the different aspects of the process in nature and to gain insights into the genetic basis and the evolutionary mechanisms of chemosensory trait divergence. Although most studies of chemosensory speciation concern sexual isolation mediated by pheromone divergence, especially in Drosophila and moth species, other chemically based behaviours (habitat choice, pollinator attraction) can also play an important role in speciation and are likely to do so in a wide range of invertebrate and vertebrate species. Adaptive divergence of chemosensory traits in response to factors such as pollinators, hosts and conspecifics commonly drives the evolution of chemical prezygotic barriers. Although the genetic basis of chemosensory speciation remains largely unknown, genomic approaches to chemosensory gene families and to enzymes involved in biosynthetic pathways of signal compounds now provide new opportunities to dissect the genetic basis of these complex traits and of their divergence among taxa.
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214
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Kocyan A, Vogel EFD, Conti E, Gravendeel B. Molecular phylogeny of Aerides (Orchidaceae) based on one nuclear and two plastid markers: A step forward in understanding the evolution of the Aeridinae. Mol Phylogenet Evol 2008; 48:422-43. [DOI: 10.1016/j.ympev.2008.02.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 01/19/2008] [Accepted: 02/02/2008] [Indexed: 10/22/2022]
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215
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Schlüter PM, Schiestl FP. Molecular mechanisms of floral mimicry in orchids. TRENDS IN PLANT SCIENCE 2008; 13:228-235. [PMID: 18424223 DOI: 10.1016/j.tplants.2008.02.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 02/04/2008] [Accepted: 02/12/2008] [Indexed: 05/26/2023]
Abstract
Deceptive plants do not produce floral rewards, but attract pollinators by mimicking signals of other organisms, such as food plants or female insects. Such floral mimicry is particularly common in orchids, in which flower morphology, coloration and odour play key roles in deceiving pollinators. A better understanding of the molecular bases for these traits should provide new insights into the occurrence, mechanisms and evolutionary consequences of floral mimicry. It should also reveal the molecular bases of pollinator-attracting signals, in addition to providing strategies for manipulating insect behaviour in general. Here, we review data on the molecular bases for traits involved in floral mimicry, and we describe methodological advances helpful for the functional evaluation of key genes.
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Affiliation(s)
- Philipp M Schlüter
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, Zurich, Switzerland.
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216
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Effect of nectar supplementation on male and female components of pollination success in the deceptive orchid Dactylorhiza sambucina. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2008. [DOI: 10.1016/j.actao.2008.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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217
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Associations between floral specialization and species diversity: cause, effect, or correlation? Evol Ecol 2008. [DOI: 10.1007/s10682-008-9259-z] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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218
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219
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Scopece G, Widmer A, Cozzolino S. Evolution of postzygotic reproductive isolation in a guild of deceptive orchids. Am Nat 2008; 171:315-26. [PMID: 18198999 DOI: 10.1086/527501] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The evolution of reproductive barriers is of central importance for speciation. Here, we investigated three components of postzygotic isolation-embryo mortality, hybrid inviability, and hybrid sterility-in a group of food-deceptive Mediterranean orchids from the genera Anacamptis, Neotinea, and Orchis. In these orchids, pollinator-mediated isolation is weak, which suggests that postpollination barriers exist. Based on crossing experiments and a literature survey, we found that embryo mortality caused complete reproductive isolation among 36.3% of the species pairs, and hybrid inviability affected 55.6% of the potentially hybridizing species pairs. Hybrid sterility was assessed experimentally for seven species pairs. A strong reduction of fertility in all investigated hybrids was found, together with clear differences between male and female components of hybrid sterility. Postzygotic isolation was found to evolve gradually with genetic divergence, and late postzygotic isolation (i.e., hybrid inviability and sterility) evolved faster than embryo mortality, which is an earlier postzygotic isolation stage. These results reveal that intrinsic postzygotic isolation strongly contributes to maintaining species boundaries among Mediterranean food-deceptive orchids while establishing a prominent role for these reproductive barriers in the early stage of species isolation.
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Affiliation(s)
- Giovanni Scopece
- Dipartimento delle Scienze Biologiche, Università degli Studi di Napoli Federico II, Via Foria 223, I-80139 Naples, Italy
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220
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Effects of population size and forest management on genetic diversity and structure of the tuberous orchid Orchis mascula. CONSERV GENET 2008. [DOI: 10.1007/s10592-008-9543-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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221
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Li P, Luo Y, Bernhardt P, Kou Y, Perner H. Pollination of Cypripedium plectrochilum (Orchidaceae) by Lasioglossum spp. (Halictidae): the roles of generalist attractants versus restrictive floral architecture. PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10:220-230. [PMID: 18304196 DOI: 10.1111/j.1438-8677.2007.00020.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The pollination of Cypripedium plectrochilum Franch. was studied in the Huanglong Nature Reserve, Sichuan, China. Although large bees (Bombus, Apis), small bees (Ceratina, Lasioglossum), ants (Formica sp.), true flies (Diptera) and a butterfly were all found to visit the flowers, only small bees, including three Lasioglossum spp. (L. viridiclaucum, L. sichuanense and L. sp.; Halictidae) and one Ceratina sp., carried the flower's pollen and contacted the receptive stigma. Measurements of floral architecture showed that interior floral dimensions best fit the exterior dimensions of Lasioglossum spp., leading to the consistent deposition and stigmatic reception of dorsally-placed, pollen smears. The floral fragrance was dominated by one ketone, 3-methyl-Decen-2-one. The conversion rate of flowers into capsules in open (insect) pollinated flowers at the site was more than 38%. We conclude that, while pigmentation patterns and floral fragrance attracted a wide variety of insect foragers, canalization of interior floral dimensions ultimately determined the spectrum of potential pollinators in this generalist, food-mimic flower. A review of the literature showed that the specialised mode of pollination-by-deceit in C. plectrochilum, limiting pollinators to a narrow and closely related guild of 'dupes' is typical for other members of this genus.
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Affiliation(s)
- P Li
- School of Life Sciences and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan, China
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222
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Shefferson RP, Kull T, Tali K. Mycorrhizal interactions of orchids colonizing Estonian mine tailings hills. AMERICAN JOURNAL OF BOTANY 2008; 95:156-64. [PMID: 21632341 DOI: 10.3732/ajb.95.2.156] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Northeastern Estonia is home to extensive oil shale mines. Associated with these are desolate and environmentally damaging hills of ash and semicoke tailings. Interestingly, some of the first plants to colonize these hills are rare orchids. Here, we assess the identities of the mycorrhizal fungi associated with these orchids, in particular Epipactis atrorubens, Orchis militaris, and Dactylorhiza baltica, and compare them with mycorrhizal fungi from orchids from pristine habitat. Epipactis atrorubens associated with the widest breadth of fungi, including unnamed members of the basidiomycete family Tulasnellaceae and the potentially ectomycorrhizal ascomycetes Trichophaea woolhopeia and Geopora cooperi. Orchis militaris also associated with unnamed members of the Tulasnellaceae. Dactylorhiza baltica associated with Ceratobasidium albasitensis. In Epipactis and Orchis, the same fungi associated with plants in the pristine habitat as with those on ash hills. The tulasnelloid and ceratobasidioid fungi mycorrhizal with these orchids appear closely related to common orchid mycorrhizal fungi, while one of the ascomycetes mycorrhizal with E. atrorubens is closely related to a mycorrhizal fungus with E. microphylla. Our results suggest that these orchids and their fungi are not limited to pristine habitats and that environmentally polluted sites may present novel habitats that may be exploited for endangered plant conservation.
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Affiliation(s)
- Richard P Shefferson
- Microbial Ecology Laboratory, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba 305-8687 Japan
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223
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Mondragón-Palomino M, Theissen G. MADS about the evolution of orchid flowers. TRENDS IN PLANT SCIENCE 2008; 13:51-9. [PMID: 18262819 DOI: 10.1016/j.tplants.2007.11.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 11/11/2007] [Accepted: 11/12/2007] [Indexed: 05/05/2023]
Abstract
Orchids have unique flowers involving three types of perianth organs: outer tepals, lateral inner tepals, and a lip. Expression studies indicate that the identity of these organs is specified by the combinatorial interaction of four different DEFICIENS-like MADS-box genes. We suggest that clarifying the evolution of these genes provides a rational framework for reconstructing the enigmatic origin and unique diversification of the orchid flower. For example, two rounds of gene duplications during early orchid evolution might have generated the genes that were probably recruited to distinguish the different types of perianth organs. This hypothesis suggests intriguing, experimentally testable mechanisms by which gene duplications followed by sub- and neo-functionalization events might have contributed to the evolutionary origin of morphological novelties in orchids - and well beyond.
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224
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Schiestl FP, Cozzolino S. Evolution of sexual mimicry in the orchid subtribe orchidinae: the role of preadaptations in the attraction of male bees as pollinators. BMC Evol Biol 2008; 8:27. [PMID: 18226206 PMCID: PMC2267782 DOI: 10.1186/1471-2148-8-27] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 01/28/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Within the astonishing diversity of orchid pollination systems, sexual deception is one of the most stunning. An example is the genus Ophrys, where plants attract male bees as pollinators by mimicking female mating signals. Unsaturated hydrocarbons (alkenes) are often the key signal for this chemical mimicry. Here we investigate the evolution of these key compounds within Orchidinae by mapping their production in flowers of selected species onto their estimated phylogeny. RESULTS We found that alkenes, at least in trace amounts, were present in 18 of 20 investigated species together representing 10 genera. Thus, the reconstruction of ancestral state for alkene-production showed that this is a primitive character state in Ophrys, and can be interpreted as a preadaptation for the evolution of sexual deception. Four of the investigated species, namely Ophrys sphegodes, Serapias lingua, S. cordigera, and Anacamptis papilionacea, that are pollinated primarily by male bees, produced significantly larger amounts and a greater number of different alkenes than the species pollinated either primarily by female bees or other insects. CONCLUSION We suggest that high amounts of alkenes evolved for the attraction of primarily male bees as pollinators by sensory exploitation, and discuss possible driving forces for the evolution of pollination by male bees.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Salvatore Cozzolino
- Università degli Studi di Napoli "Federico II", Dipartimento delle Scienze Biologiche, Via Foria 223, 80139 Napoli, Italy
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225
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Zhongjian L, Lijun C, Wenhui R, Liqiang L, Yuting Z. Correlation between numerical dynamics and reproductive behavior in Cypripedium lentiginosum. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1872-2032(08)60021-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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226
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ROBERTS DAVIDL, BATEMAN RICHARDM. Do ambush predators prefer rewarding or non-rewarding orchid inflorescences? Biol J Linn Soc Lond 2007. [DOI: 10.1111/j.1095-8312.2007.00938.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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227
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228
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SWARTS NIGELD, SINCLAIR ELIZABETHA, DIXON KINGSLEYW. Characterization of microsatellite loci in the endangered grand spider orchid Caladenia huegelii (Orchidaceae). ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1471-8286.2007.01810.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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229
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García-Cruz J, Sosa V. Fruit production and floral traits: correlated evolution in Govenia (Orchidaceae). Evol Ecol 2007. [DOI: 10.1007/s10682-007-9210-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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230
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MAKINO TT, SAKAI S. Experience changes pollinator responses to floral display size: from size-based to reward-based foraging. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01293.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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231
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Genetic diversity of wild Cymbidium goeringii (Orchidaceae) populations from Hubei based on Inter-simple sequence repeats analysis. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11515-007-0064-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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232
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Scopece G, Musacchio A, Widmer A, Cozzolino S. Patterns of reproductive isolation in Mediterranean deceptive orchids. Evolution 2007; 61:2623-42. [PMID: 17908246 DOI: 10.1111/j.1558-5646.2007.00231.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The evolution of reproductive isolation is of central interest in evolutionary biology. In plants, this is typically achieved by a combination of pre- and postpollination mechanisms that prevent, or limit, the amount of interspecific gene flow. Here, we investigated and compared two ecologically defined groups of Mediterranean orchids that differ in pollination biology and pollinator specificity: sexually deceptive orchids versus food-deceptive orchids. We used experimental crosses to assess the strength of postmating prezygotic, and postzygotic reproductive isolation, and a phylogenetic framework to determine their relative rates of evolution. We found quantitative and qualitative differences between the two groups. Food-deceptive orchids have weak premating isolation but strong postmating isolation, whereas the converse situation characterizes sexually deceptive orchids. Only postzygotic reproductive isolation among food-deceptive orchids was found to evolve in a clock-like manner. Comparison of evolutionary rates, within a common interval of genetic distance, showed that the contribution of postmating barriers was more relevant in the food-deceptive species than in the sexually deceptive species. Asymmetry in prezygotic isolation was found among food-deceptive species. Our results indicate that postmating barriers are most important for reproductive isolation in food-deceptive orchids, whereas premating barriers are most important in sexually deceptive orchids. The different rate of evolution of reproductive isolation and the relative strength of pre- and postmating barriers may have implication for speciation processes in the two orchid groups.
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Affiliation(s)
- Giovanni Scopece
- Dipartimento delle Scienze Biologiche, Università degli Studi di Napoli Federico II, Via Foria, 223, I-80139 Naples, Italy.
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233
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Abstract
The Orchidaceae is renowned for its large number of species (19,500) and its many diverse, even bizarre, specialized pollination systems. One unusual feature of orchids is the high frequency of food deception whereby animal pollination is achieved without providing nectar, pollen or other food rewards. Food-deceptive pollination is estimated to occur in approximately one-third of all orchids. Equally intriguing is pollination by sexual deception whereby pollination is achieved by the sexual attraction of male insects to the orchid flower. Sexual deception is found in several hundred species representing multiple lineages. Given their rich species diversity and extraordinary plant-animal interactions, orchids clearly offer exciting research opportunities in pollination biology, reproductive isolation and speciation, yet surprisingly they remain under-represented in scientific investigations both in these fields and more generally. In this special issue of Molecular Ecology, Moccia et al. provide an exemplar study that combine multiple lines of evidence to illuminate the mechanism of reproductive isolation between two closely related food-deceptive orchids. Their study demonstrates that many of the challenges that confront orchid researchers and impede progress in our understanding of speciation in the Orchidaceae can be overcome by the creative application and integration of both old and new tools in ecology and genetics.
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234
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Shefferson RP, Taylor DL, Weiss M, Garnica S, McCormick MK, Adams S, Gray HM, McFarland JW, Kull T, Tali K, Yukawa T, Kawahara T, Miyoshi K, Lee YI. THE EVOLUTIONARY HISTORY OF MYCORRHIZAL SPECIFICITY AMONG LADY'S SLIPPER ORCHIDS. Evolution 2007; 61:1380-90. [PMID: 17542847 DOI: 10.1111/j.1558-5646.2007.00112.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although coevolution is acknowledged to occur in nature, coevolutionary patterns in symbioses not involving species-to-species relationships are poorly understood. Mycorrhizal plants are thought to be too generalist to coevolve with their symbiotic fungi; yet some plants, including some orchids, exhibit strikingly narrow mycorrhizal specificity. Here, we assess the evolutionary history of mycorrhizal specificity in the lady's slipper orchid genus, Cypripedium. We sampled 90 populations of 15 taxa across three continents, using DNA methods to identify fungal symbionts and quantify mycorrhizal specificity. We assessed phylogenetic relationships among sampled Cypripedium taxa, onto which we mapped mycorrhizal specificity. Cypripedium taxa associated almost exclusively with fungi within family Tulasnellaceae. Ancestral specificity appears to have been narrow, followed by a broadening after the divergence of C. debile. Specificity then narrowed, resulting in strikingly narrow specificity in most of the taxa in this study, with no taxon rewidening to the same extant as basal members of the genus. Sympatric taxa generally associated with different sets of fungi, and most clades of Cypripedium-mycorrhizal fungi were found throughout much of the northern hemisphere, suggesting that these evolutionary patterns in specificity are not the result of biogeographic lack of opportunity to associate with potential partners. Mycorrhizal specificity in genus Cypripedium appears to be an evolvable trait, and associations with particular fungi are phylogenetically conserved.
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235
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Moccia MD, Widmer A, Cozzolino S. The strength of reproductive isolation in two hybridizing food-deceptive orchid species. Mol Ecol 2007; 16:2855-66. [PMID: 17614902 DOI: 10.1111/j.1365-294x.2007.03240.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Reproductive isolation is of fundamental importance for maintaining species boundaries in sympatry. In orchids, the wide variety of pollination systems and highly diverse floral traits have traditionally suggested a prominent role for pollinator isolation, and thus for prezygotic isolation, as an effective barrier to gene flow among species. Here, we examined the nature of reproductive isolation between Anacamptis morio and Anacamptis papilionacea, two sister species of Mediterranean food-deceptive orchids, in two natural hybrid zones. Comparative analyses of the two hybrid zones that are located on soils with volcanic origin and have different and well-dated ages consistently revealed that all hybrid individuals were morphologically and genetically intermediate between the parental species, but had strongly reduced fitness. Molecular analyses based on nuclear ITS1 and (amplified fragment length polymorphism) AFLP markers clearly showed that all examined hybrids were F1 hybrids, and that no introgression occurred between parental species. The maternally inherited plastid DNA markers indicated that hybridization between A. morio and A. papilionacea was bidirectional, as confirmed by the molecular analysis of seed families. The genetic architecture of the two hybrid zones suggests that the two parental species easily and frequently hybridize in sympatry as a consequence of partial pollinator overlap but that strong postzygotic barriers reduce hybrid fitness and prevent gene introgression. These results corroborate that chromosomal divergence is instrumental for reproductive isolation between these food-deceptive orchids and suggest that hybridization is of limited importance for their diversification.
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Affiliation(s)
- Maria Domenica Moccia
- Dipartimento delle Scienze Biologiche, Università degli Studi di Napoli Federico II, Via Foria, 223, I-80139 Naples, Italy
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236
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KITCHING RL, BOULTER SL, HOWLETT BG, GOODALL K. Visitor assemblages at flowers in a tropical rainforest canopy. AUSTRAL ECOL 2007. [DOI: 10.1111/j.1442-9993.2007.01733.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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237
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Jacquemyn H, Brys R, Vandepitte K, Honnay O, Roldán-Ruiz I. Fine-scale genetic structure of life history stages in the food-deceptive orchid Orchis purpurea. Mol Ecol 2006; 15:2801-8. [PMID: 16911201 DOI: 10.1111/j.1365-294x.2006.02978.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In natural plant populations, fine-scale spatial genetic structure can result from limited gene flow, selection pressures or historical events, but the role of each factor is in general hard to discern. One way to investigate the origination of spatial genetic structure within a plant population consists of comparing spatial genetic structure among different life history stages. In this study, spatial genetic structure of the food-deceptive orchid Orchis purpurea was determined across life history stages in two populations that were regenerating after many years of population decline. Based on demographic analyses (2001-2004), we distinguished between recruits and adult plants. For both sites, there was no difference in the proportion of polymorphic loci and expected heterozygosity between life history stages. However, spatial autocorrelation analyses showed that spatial genetic structure increased in magnitude with life history stage. Weak or no spatial genetic structure was observed for recruits, whereas adult plants showed a pattern that is consistent with that found in other species with a predominantly outcrossing mating system. The observed differences between seedlings and adults are probably a consequence of changes in management of the two study sites and associated demographic changes in both populations. Our results illustrate that recurrent population crashes and recovery may strongly affect genetic diversity and fine-scale spatial genetic structure of plant populations.
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Affiliation(s)
- Hans Jacquemyn
- Division Forest, Nature and Landscape Research, Catholic University of Leuven, Celestijnenlaan 200E, B-3001 Leuven, Belgium.
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238
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LUMAGA MRBARONE, COZZOLINO S, KOCYAN A. Exine micromorphology of Orchidinae (Orchidoideae, Orchidaceae): phylogenetic constraints or ecological influences? ANNALS OF BOTANY 2006; 98:237-44. [PMID: 16704999 PMCID: PMC2803542 DOI: 10.1093/aob/mcl094] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
BACKGROUND AND AIMS Pollen characters have been widely used in defining evolutionary trends in orchids. In recent years, information on pollination biology and phylogenetic patterns within Orchidinae has become available. Hence, the aim of the presented work is to re-evaluate exine micromorphology of Orchidinae in light of recent phylogenetic studies and to test whether pollen micromorphology strictly depends on phylogenetic relationships among species or whether it is influenced by the marked differences in pollination ecology also reported among closely related species. METHODS Pollen sculpturing of 45 species of Orchidinae and related taxa was investigated using scanning electron microscopy. To cover potential intraspecific variation, several accessions of the same species were examined. KEY RESULTS Orchidinae show remarkable variation in exine sculpturing, with a different level of variation within species groups. In some genera, such as Serapias (rugulate) and Ophrys (psilate to verrucate), intrageneric uniformity corresponds well to a common pollination strategy and close relationships among species. However, little exine variability (psilate-scabrate and scabrate-rugulate) was also found in the genus Anacamptis in spite of striking differences in floral architecture and pollination strategies. A larger variety of exine conditions was found in genera Dactylorhiza (psilate, psilate-scabrate and reticulate) and Orchis s.s. (psilate, reticulate, perforate-rugulate and baculate) where no unequivocal correspondence can be found to either phylogenetic patterns or pollination strategies. CONCLUSIONS Changes in pollen characteristics do not consistently reflect shifts in pollination strategy. A unique trend of exine evolution within Orchidinae is difficult to trace. However, the clades comprising Anacamptis, Neotinea, Ophrys and Serapias show psilate to rugulate or scabrate pollen, while that of the clade comprising Chamorchis, Dactylorhiza, Gymnadenia, Orchis s.s., Platanthera, Pseudorchis and Traunsteinera ranges from psilate to reticulate. Comparison of the data with exine micromorphology from members of the tribe Orchidieae and related tribes suggests a possible general trend from reticulate to psilate.
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Affiliation(s)
- M. R. BARONE LUMAGA
- Orto Botanico and Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Naples, Italy and Insitute of Systematic Botany, Ludwig Maximilians University, Menzinger Strasse 67, 80638 Munich, Germany
| | - S. COZZOLINO
- Orto Botanico and Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Naples, Italy and Insitute of Systematic Botany, Ludwig Maximilians University, Menzinger Strasse 67, 80638 Munich, Germany
| | - A. KOCYAN
- Orto Botanico and Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Naples, Italy and Insitute of Systematic Botany, Ludwig Maximilians University, Menzinger Strasse 67, 80638 Munich, Germany
- For correspondence. E-mail
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Song IJ, Nakamura T, Fukuda T, Yokoyama J, Ito T, Ichikawa H, Horikawa Y, Kameya T, Kanno A. Spatiotemporal expression of duplicate AGAMOUS orthologues during floral development in Phalaenopsis. Dev Genes Evol 2006; 216:301-13. [PMID: 16463041 DOI: 10.1007/s00427-005-0057-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Accepted: 12/21/2005] [Indexed: 10/25/2022]
Abstract
The AGAMOUS (AG) family of MADS-box genes plays important roles in controlling the development of the reproductive organs of flowering plants. To understand the molecular mechanisms behind the floral development in the orchid, we isolated and characterized two AG-like genes from Phalaenopsis that we denoted PhalAG1 and PhalAG2. Phylogenetic analysis indicated that PhalAG1 and PhalAG2 fall into different phylogenetic positions in the AG gene family as they belong to the C- and D-lineages, respectively. Reverse transcription-polymerase chair reaction (RT-PCR) analyses showed that PhalAG1 and PhalAG2 transcripts were detected in flower buds but not in vegetative organs. Moreover, in situ hybridization experiments revealed that PhalAG1 and PhalAG2 hybridization signals were observed in the lip, column, and ovule during the floral development of Phalaenopsis, with little difference between the expression patterns of the two genes. These results suggest that both AG-like genes in Phalaenopsis act redundantly with each other in floral development.
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Affiliation(s)
- In-Ja Song
- Graduate School of Life Sciences, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
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