Effects of floral diversity and pollinator behaviour on the persistence of hybrid zones between plants sharing pollinators

Background: Plant hybrid zones often display a large diversity in floral traits due to segregation and recombination occurring in the second and later hybrid generations. Such diversity can have important effects on pollinator behaviour.

Aims: We hypothesised that the number of floral types and their relative densities may influence pollinator preferences and level of flower constancy.

Methods: To test the influence of floral diversity on the number of visits to inflorescences of the most common type and on the level of flower constancy, we monitored bumblebees’ behaviour in experimental arrays of artificial inflorescences with a common (‘parental’) floral type mixed with either one or three uncommon (‘hybrid’) floral types.

Results: We found that pollinators preferentially visited the most common flower colour and showed slightly greater constancy when the number of uncommon floral types was increased.

Conclusions: We conclude that diversity in flower colour could promote moderate pollinator constancy in some types of hybrid zones. Segregation of floral phenotypes due to hybridisation may result in small levels of pollinator-mediated assortative mating and contribute, to a small extent, and most probably in combination with other factors, to the persistence of some hybrid zones.     

Integrating environmental,molecular, and morphological data to unravel an ice‐age radiation of arctic‐alpine Campanula in western North America

Many arctic‐alpine plant genera have undergone speciation during the Quaternary. The bases for these radiations have been ascribed to geographic isolation, abiotic and biotic differences between populations, and/or hybridization and polyploidization. The Cordilleran Campanula L. (Campanulaceae Juss.), a monophyletic clade of mostly endemic arctic‐alpine taxa from western North America, experienced a recent and rapid radiation. We set out to unravel the factors that likely influenced speciation in this group. To do so, we integrated environmental, genetic, and morphological datasets, tested biogeographic hypotheses, and analyzed the potential consequences of the various factors on the evolutionary history of the clade. We created paleodistribution models to identify potential Pleistocene refugia for the clade and estimated niche space for individual taxa using geographic and climatic data. Using 11 nuclear loci, we reconstructed a species tree and tested biogeographic hypotheses derived from the paleodistribution models. Finally, we tested 28 morphological characters, including floral, vegetative, and seed characteristics, for their capacity to differentiate taxa. Our results show that the combined effect of Quaternary climatic variation, isolation among differing environments in the mountains in western North America, and biotic factors influencing floral morphology contributed to speciation in this group during the mid‐Pleistocene. Furthermore, our biogeographic analyses uncovered asynchronous consequences of interglacial and glacial periods for the timing of refugial isolation within the southern and northwestern mountains, respectively. These findings have broad implications for understanding the processes promoting speciation in arctic‐alpine plants and the rise of numerous endemic taxa across the region.     

Genetic diversity and differentiation in narrow versus widespread taxa of Helianthemum (Cistaceae) in a hotspot: The role of geographic range,habitat, and reproductive traits

Unraveling the relationships between ecological, functional traits and genetic diversity of narrow endemic plants provide opportunities for understanding how evolutionary processes operate over local spatial scales and ultimately how diversity is created and maintained. To explore these aspects in Sierra Nevada, the core of the Mediterranean Betic‐Rifean hotspot, we have analyzed nuclear DNA microsatellite diversity and a set of biological and environmental factors (physicochemical soil parameters, floral traits, and community composition) in two strictly endemic taxa from dolomite outcrops of Sierra Nevada (Helianthemum pannosum and H. apenninum subsp. estevei) and two congeneric widespread taxa (H. cinereum subsp. rotundifolium and H. apenninum subsp. apenninum) that further belong to two different lineages (subgenera) of Helianthemum. We obtained rather unexpected results contrasting with the theory: (a) The narrow endemic taxa showed higher values of genetic diversity as well as higher average values of pollen production per flower and pollen‐to‐ovule ratio than their widespread relatives; and (b) the two taxa of subg. Helianthemum, with larger corollas, approach herkogamy and higher pollen production than the two taxa of subg. Plectolobum, displayed lower genetic diversity and higher values of inbreeding. Altogether, these results disclose how genetic diversity may be affected simultaneously by a large number of intrinsic and extrinsic factors, especially in Pleistocene glacial refugia in mountains where the spatial context harbors a great ecological heterogeneity. On the other hand, differences in mating system and the significant effect of the substrate profile, both being highly diverse in the genus Helianthemum, in the genetic variability illustrate about the importance of these two factors in the diversification and species differentiation of this paradigmatic genus in the Mediterranean and open the field to formulate and test new hypotheses of local adaptation, trait evolution, and habitat diversification.     

Reconstructing the history of Campanulaceae with a Bayesian approach to molecular dating and dispersal–vicariance analyses

We reconstruct here the spatial and temporal evolution of the Campanula alliance in order to better understand its evolutionary history. To increase phylogenetic resolution among major groups (Wahlenbergieae–Campanuleae), new sequences from the rbcL region were added to the trnL-F dataset obtained in a previous study. These phylogenies were used to infer ancestral areas and divergence times in Campanula and related genera using a Bayesian approach to molecular dating and dispersal–vicariance analyses that takes into account phylogenetic uncertainty. The new phylogenetic analysis confirms Platycodoneae as the sister group of Wahlenbergieae–Campanuleae, the two last ones inter-graded into a well-supported clade. Biogeographic and dating analyses suggest that Western Asia and the Eastern Mediterranean have played a major role as centers of migration and diversification within the Campanula alliance, probably in relation to the intense orogenic activity that took place in this region during the Late Neogene, and that could have promoted isolation and allopatric speciation within lineages. Diversification rates within several Campanula lineages would have increased at the end of the Miocene, coinciding with the Messinian Stage. Strong selective pressures from climate changes and the expansion of mountainous regions during this period are suggested to explain the adaptation to drought, cold or disturbed environments observed in many Campanula species. Several independent long-distance dispersal events to North America are inferred within the Rapunculus clade, which seem to be related to high ploidy levels.     

PLANT POLYPLOIDY AND POLLINATION: FLORAL TRAITS AND INSECT VISITS TO DIPLOID AND TETRAPLOID HEUCHERA GROSSULARIIFOLIA

In many polyploid species, polyploids often have different suites of floral traits and different flowering times than their diploid progenitor species. We hypothesized that such differences in floral traits in polyploids may subsequently affect their interactions with pollinating and other insect visitors. We measured floral morphology and flowering phenology in 14 populations of diploid and autotetraploid Heuchera grossulariifolia Rydb. (Saxifragaceae), determined if repeated evolution of independent polyploid lineages resulted in differentiation in floral morphology among those lineages, and ascertained if there was a consistent pattern of differentiation among genetically similar diploid and autotetraploid populations. In addition, we evaluated the differences in suites of floral visitors within a natural community where diploids and autotetraploids occur sympatrically. Overall, flowers of autotetraploid plants were larger and shaped differently than those of diploids, had a different flowering phenology than that of diploids, and attracted different suites of floral visitors. In comparison with flowers of diploids, tetraploid floral morphology varied widely from pronounced differences between cytotypes in some populations to similar flower shapes and sizes between ploidal levels in other populations. Observations of floral visitors to diploids and autotetraploids in a natural sympatric population demonstrated that the cytotypes had different suites of floral visitors and six of the 15 common visitors preferentially visited one ploidy more frequently. Moreover, we also found that floral morphology differed among independent autotetraploid origins, but there was no consistent pattern of differentiation between genetically similar diploid and autotetraploid populations. Hence, the results suggest that the process of polyploidization creates the potential for attraction of different suites of floral visitors. Multiple origins of polyploidy also presents the opportunity for new or different plant-insect interactions among independent polyploid lineages. These differences in turn may affect patterns of gene flow between diploids and polyploids and also among plants of independent polyploid origin. Polyploidy, therefore, may result in a geographic mosaic of interspecific interactions across a species' range, contributing to diversification in both plant and insect groups.     

Visual and Olfactory Floral Cues of Campanula (Campanulaceae) and Their Significance for Host Recognition by an Oligolectic Bee Pollinator

Oligolectic bees collect pollen from a few plants within a genus or family to rear their offspring, and are known to rely on visual and olfactory floral cues to recognize host plants. However, studies investigating whether oligolectic bees recognize distinct host plants by using shared floral cues are scarce. In the present study, we investigated in a comparative approach the visual and olfactory floral cues of six Campanula species, of which only Campanula lactiflora has never been reported as a pollen source of the oligolectic bee Ch. rapunculi. We hypothesized that the flowers of Campanula species visited by Ch. rapunculi share visual (i.e. color) and/or olfactory cues (scents) that give them a host-specific signature. To test this hypothesis, floral color and scent were studied by spectrophotometric and chemical analyses, respectively. Additionally, we performed bioassays within a flight cage to test the innate color preference of Ch. rapunculi. Our results show that Campanula flowers reflect the light predominantly in the UV-blue/blue bee-color space and that Ch. rapunculi displays a strong innate preference for these two colors. Furthermore, we recorded spiroacetals in the floral scent of all Campanula species, but Ca. lactiflora. Spiroacetals, rarely found as floral scent constituents but quite common among Campanula species, were recently shown to play a key function for host-flower recognition by Ch. rapunculi. We conclude that Campanula species share some visual and olfactory floral cues, and that neurological adaptations (i.e. vision and olfaction) of Ch. rapunculi innately drive their foraging flights toward host flowers. The significance of our findings for the evolution of pollen diet breadth in bees is discussed.     

Fruit production and floral traits: correlated evolution in <Emphasis Type="Italic">Govenia</Emphasis> (Orchidaceae)

The most common estimate of reproductive success in orchids is usually fruit set. Factors such as resource limitation and certain floral traits may influence reproductive success in animal-pollinated plants. Correlated evolution of reproductive success vs. seven floral traits (inflorescence length, flower number, flower distribution along inflorescence, dorsal sepal length, lateral sepal length, flower color, and column position) was studied in eight species of Govenia. Taxa represented three lineages in the genus. Independent contrasts were calculated on a phylogeny inferred from chloroplast (trnL-F IGS) DNA sequences, and a correlation test and multiple regression were then performed. Two data sets were evaluated, one including all eight species and another excluding G. utriculata, which is autogamous. The historical analyses showed that there is a correlation between reproductive success and dorsal sepal length, column position, and flower number, these correlations suggest that changes in these floral traits usually accompany evolutionary shifts in reproductive success. Multiple regression tests suggest that changes in reproductive success can be explained by shifts in flower number, inflorescence length, column position and by dorsal sepal length. When phylogeny is taken into account, our analyses showed that evolutionary shifts in these floral traits were correlated with changes in reproductive success. Evolutionary correlation between reproductive success and floral traits might be explained by the natural selection of certain floral phenotypes by pollinators.     

Missing links: the genetic architecture of flower and floral diversification

To understand the genetic architecture of floral development, including the origin and subsequent diversification of the flower, data are needed not only for a few model organisms but also for gymnosperms, basal angiosperm lineages and early-diverging eudicots. We must link what is known about derived model plants such as Arabidopsis, snapdragon and maize with other angiosperms. To this end, we suggest a massive evolutionary genomics effort focused on the identification and expression patterns of floral genes and elucidation of their expression patterns in ‘missing-link’ taxa differing in the arrangement, number and organization of floral parts.     

DEVELOPMENT AND VASCULATURE OF THE FLOWERS OF LOPHOTOCARPUS CALYCINUS AND SAGITTARIA LATIFOLIA (ALISMACEAE)

The development of the bisexual flower of Lophotocarpus calycinus and of the unisexual flowers of Sagittaria latifolia has been observed. In all eases floral organs arise in acropetal succession. In L. calycinus, after initiation of the perianth, the first whorl of stamens to form consists of six stamens and is ordinarily followed by two alternating whorls of six stamens each. The very numerous carpels arc initiated spirally. In the male flower of S. latifolia the androecium develops in spiral order. A few rudimentary carpels appear near the floral apex after initiation of the stamens. There are no staminodia. The female flower has a similar developmental pattern to that of Lophotocarpus except that a prominent residual floral apex is left bare of carpels. The vascular system in all flowers is semiopen, with vascular bundles passing to the floral organs in a pattern unrelated to the relative positions of those organs. The androecia of these two taxa are similar to those of some Butomaceae and relationships based on ontogeny and morphology are suggested. The gynoecia are meristically less specialized but morphologically more specialized than the gynoecia of Butomaceae.     

Mouthpart evolution in adults of the basal, 'symphytan', hymenopteran lineages

We review feeding biology and mouthpart structure generally among adults of the basal hymenopteran, or ‘symphytan’, lineages (sawflies, woodwasps, horntails and their relatives). These insects feed on a wide range of materials: floral and extrafloral nectar, pollen, plant (floral and leaf) tissues, plant (angiosperm) sap, the juice of ripe fruit, die spermatial fluid of rust fungi, sternorrhynchan bug honeydew, and insect tissues. Adults show feeding‐related mouthpart specialization either for consuming pollen (the Xyelidae only) or for consuming ‘concealed’ floral nectar (several families). Seven functional types of elongated proboscis or ‘concealed‐nectar extraction apparatus (GNEA)’ have previously been recognized among Hymenoptera. We identify an additional type, which appears to be unique among Hy‐menoptera and has probably evolved direcdy from unspecialized mouthparts (labiomaxillary complex). In total, three types of CNEA are known to occur in ‘Symphyta’. Type 1 occurs in Pamphiliidae, Megalodontesidae, Argidae, Pergidae, Tenthredinidae, Cimbicidae and Cephidae. Type 5 occurs in Pergidae (in two unidentified species of Euryinae). Type 8 occurs in Tenthredinidae (in the genus Nipponorhynchus Takeuchi). CNEA of some type or other has arisen at least twice within the family Tenthredinidae and at least twice widiin die pergid subfamily Euryinae. Evolutionary parallelism in CNEA structure has occurred between the basal, ‘symphytan’, hymenopteran lineages and die Apocrita, a phenomenon hitherto not mentioned in the literature. Within the ‘Symphyta’, possession of Type 1 CNEA appears to be a ground plan feature of each of the following taxa: the pergid genus Eurys Newman, the megalodontesid genus Megalodontes Latreille (the only extant representative of the Megalodontesidae) and the tenthredinid genus Cuneala Zirngiebl, while possession of Type 8 appears to be a ground plan feature of die tenthredinid genus Mpponorhynchus Takeuchi. However, in general among ‘Symphyta’, possession of CNEA is characteristic of only small and taxonomically subordinate groups, suggesting that CNEA has evolved independendy many times within the basal hymenopteran lineages rather than being inherited from a common ancestor early in the evolutionary history of the Hymenoptera. In other words, ecological expediency radier than phylogenetic history mainly accounts for its distribution pattern within the basal lineages. The results of a morphological survey of ‘Symphyta’ indicate that the habit of exploiting ‘concealed nectar’, by means of CNEA, is fairly     

Foraging strategies of generalist and specialist Old World nectar bats in response to temporally variable floral resources

Foraging theory predicts that generalist foragers should switch resources more readily, while specialist foragers should remain constant to preferred food resources. Plant‐pollinator interactions provide a convenient system to test such predictions because floral resources are often temporally patchy, thus requiring long‐lived pollinators to switch resources seasonally. Furthermore, flowering phenologies range from ‘steady‐state’ (low‐rewarding but highly reliable) to ‘big‐bang’ (high‐rewarding but ephemeral) plant species. We assessed how nectarivorous Old World bats respond to this temporally variable floral environment by examining their diets throughout the year. Over 15 months of fieldwork in southern Thailand, we simultaneously: (1) recorded the flowering phenologies of six bat‐pollinated plant taxa; and (2) assessed the diets of seven common flower‐visiting bat species. As predicted, the generalist nectarivore (Eonycteris spelaea) frequently switched diets and utilized both big‐bang and steady‐state resources, while the specialist nectarivores (Macroglossus minimus and M. sobrinus) foraged on one or two steady‐state plant species year‐round. Our results suggest that larger and faster bat species are able to fly longer distances in search of big‐bang resources, while smaller bat species rely on highly predictable food resources. This study supports the theory that generalist foragers have flexible diets, while specialist species restrict foraging to preferred floral resources even when other floral resources are more abundant. Moreover, these findings demonstrate how plant flowering phenology and pollinator diet breadth can shape the frequency and constancy of pollinator visits; we further discuss how such interactions can influence the potential extent of gene flow within a patchy floral environment.     

Is floral morphology a good predictor of floral visitors to Antirrhineae (snapdragons and relatives)?

• The association between plants and flower visitors has been historically proposed as a main factor driving the evolutionary change of both flower and pollinator phenotypes. The considerable diversity in floral morphology within the tribe Antirrhineae has been traditionally related to pollinator types. We used empirical data on the flower visitors from 59 Antirrhineae taxa from the literature and our own field surveys, which provide an opportunity to test whether flower phenotypes are reliable predictors of visitors and pollinator niches.
• The degree of adjustment between eight key floral traits and actual visitors was explored by testing the predictive value of inferred pollinator syndromes (i.e. suites of floral traits that characterise groups of plant species related to pollination). Actual visitors and inferred pollinator niches (categorisation of visitors’ association using a modularity algorithm) were also explored using Linear Discriminant Analysis (LDA).
• The bee pollinator niche is correctly classified for flowers with dull corolla colour, without nectar guides, as the most important predictor. Both predictive value and statistical classification prove useful in classifying Antirrhineae taxa and the bee pollinator niche, mostly as a consequence of the high proportion of genera and taxa with occluded corollas primarily visited by bees. Our predictive approach rendered a high Positive Predictive Value (PPV) of floral traits in the diagnosis of visitors/pollinator niches. In particular, a high PPV was found for bees as both visitors and forming pollinator niches. In addition, LDA showed that four pollinator niches are well defined based on floral traits.
• The large number of species visited by bees irrespective of pollinator syndromes leads us to hypothesise their generalist pollinator role, despite the phenotypically specialised flowers of Antirrhineae.

     

Bird–flower interactions in the Macaronesian islands

Aims Several bird‐pollinated or ornithophilous flowers are present on the Macaronesian archipelagos, the Canary Islands and Madeira, but absent from nearby NW Africa and Europe. In Macaronesia, no specialist nectar‐feeding birds are found, but several generalist passerine bird species visit flowers for nectar. Two hypotheses attempt to explain the origin and evolution of ornithophily in the Macaronesian flora. According to ‘the island de novo hypothesis’, bird‐flowers evolved from mainland insect‐pollinated ancestors after island colonization. Alternatively, ancestors of the ornithophilous Macaronesian plant species evolved bird‐flowers before reaching the islands (‘the relict hypothesis’). In this study we first compile information of Macaronesian bird–flower interactions from the literature and our own field observations. Secondly, we discuss the two hypotheses of origin of ornithophily in the light of evidence from recent molecular plant phylogenies, palaeontology, historical biogeography of the African avifauna and flora, and present‐day ecological patterns. Location Madeira and Canary Islands. Results At least eleven endemic Macaronesian plant species from six genera have typical ornithophilous floral traits. These genera are: Canarina and Musschia (Campanulaceae), Isoplexis (Scrophulariaceae), Echium (Boraginaceae), Lotus (Fabaceae) and Lavatera (Malvaceae). These lineages have clear affinities to the Mediterranean region, except for Canarina whose closest relatives grow in East African mountains. Six generalist passerine bird species of Sylvia, Phylloscopus (Sylviidae), Serinus (Fringillidae) and Parus (Paridae) visit this flora for nectar. Main conclusion We suggest that the origin and evolution of ornithophilous traits in these plant species took place mostly in mainland areas prior to island colonization. In Canarina and Lavatera, it is well supported that ornithophily is a relict condition, which originated in mainland areas possibly in association with specialist nectar‐feeding birds. For the remaining plant species except Echium wildpretii bird floral traits probably also are a relict condition. These species may be derived from ancestors, which were visited by specialist nectar‐feeding birds during geological periods when the Mediterranean and the Ethiopian vegetation were intermingled in mainland Africa. Probably, these mainland ancestors went extinct due to severe climatic fluctuations, while their Macaronesian descendants survived in ‘refuge’ on the islands. Finally, the island de novo hypothesis may explain the evolution of a mixed bird/insect‐pollination system in the neo‐endemic red‐flowered Echium wildpretii.     

Comparative flower development of Juglans regia,Cyclocarya paliurus and Engelhardia spicata: homology of floral envelopes in Juglandaceae

Homology among reproductive structures is pivotal for understanding angiosperm evolution. In Juglandaceae, homologies of floral parts have been disputed due to morphological variability in flowers. Previous interpretations were based mainly on mature flowers and lacked developmental studies. We investigated the unisexual flower development of Juglans regia, Cyclocarya paliurus and Engelhardia spicata using scanning electron microscopy. The ‘floral envelope’ of staminate flowers in J. regia and C. paliurus consists of a bract and several tepals. Six tepals are initiated in a whorled pattern in J. regia, whereas four to six tepals are arranged in a variable pattern in C. paliurus. The three‐lobed bract of E. spicata results from the cleavage of an entire bract, rather than adnation of the bract and its bracteoles. Pistillate flowers of J. regia and C. paliurus, subtended by a bract and a horseshoe‐shaped bracteole, usually have four tepals initiating simultaneously in one whorl. The organogenesis patterns of the ‘floral envelope’ and stamens in staminate flowers show greater diversity, indicating different degrees of reduction among genera. Our floral developmental data support the division of Juglandaceae into two subfamilies and then further into three tribes.     

Comparative phylogeography of capitulate <Emphasis Type="Italic">Campanula</Emphasis> species from the Balkans,with description of a new species, <Emphasis Type="Italic">C. daucoides</Emphasis>

Capitulate inflorescence is a specific, strongly adaptive and rare feature in the genus Campanula. We studied morphologically eight capitulate Campanula taxa from the Balkans (1537 individuals/52 populations) and one more species from Caucasus at the molecular level (using chloroplast markers trnG^UCC-trnS^GCU and psbA-trnH, 130 individuals/58 populations) to assess their relations and evolutionary histories. Although all studied taxa were well circumscribed at both the morphological and molecular levels (except morphologically distinct but genetically invariable C. moesiaca which acquired its single haplotype via past cytoplasmic introgression from C. cervicaria), their relations inferred from the two datasets were incongruent possibly due to the homoplasy of morphological characters frequently reported in Campanula. Interspecific hybridization and introgression affected majority of studied species and may be more common in Campanula than previously thought. These processes, along with incomplete lineage sorting and retention of ancestral polymorphisms, hampered our phylogenetic reconstructions and prevented us to fully resolve species relations, and to support monophyletic origin of capitulate Campanula species. Nonetheless, several cryptic taxa were delineated, and C. daucoides was described as a new capitulate Campanula species. Different evolutionary histories and multiple glacial refugia were inferred for all species represented by multiple samples (except C. moesiaca). According to our dating, their speciation was in most cases triggered by various geo-historic events such as the uplift of the Alpide belt, Messinian Salinity Crisis, or desiccation of the Pannonian Sea/Pliocene Lakes from the central Balkans, while their further diversification was mainly driven by the onset of the Quaternary and cycles of glacials/interglacials.     

Desert spring refugia: museums of diversity or evolutionary cradles?

Refugia play a critical role in preserving species unable to move or adapt to cope with environmental change. The role of refugia as ‘museums of diversity’ means these environments have a high conservation priority. Less well known, however, is the role that isolated and fragmented refugia can play in the generation of new diversity. Here, we examined the diversification and evolutionary history of a community of endemic invertebrates that inhabit Australian desert spring refugia. We compared the phylogenies of seven endemic groups (Haloniscus and Phreatomerus isopods, chiltoniid amphipods, Ngarawa ostracods, Trochidrobia and Fonscochlea snails and Gymnochthebius beetles) from these springs and examine the rates and timing of diversification and reconstructed the phylogeographic history of each taxon. Despite major life‐history differences among these taxa, they demonstrate remarkable similarities in their evolutionary histories. All groups have multiple lineages that extend back to a time before the formation of present‐day deserts, and significant geographic‐based diversification since adapting to a refugial habitat. The results provide further evidence that refugia act as museums of biodiversity, preserving lineages that would have otherwise gone extinct. However, we also observed that isolation in refugia corresponds with significant diversification, leading to a recently evolved, novel endemic fauna, supporting the idea that fragmented refugia provide ideal conditions for the generation of future biodiversity hotspots.     

Floral and pollinator behaviour of flexistylous Bornean ginger, Alpinia nieuwenhuizii (Zingiberaceae)

Flexistyly is a unique floral mechanism involving extreme curving of the style. It was first described in Chinese ginger (Amomum, Zingiberaceae). This is a pioneer report on flexistylous gingers of Malesia, where most species of this family grow. We observed the floral behaviour and flower visitors in Alpinia nieuwenhuizii Val., a Bornean endemic. Although the floral behaviour and effective pollinators (carpenter bees, Xylocopa) were similar between the Bornean species and the previously reported flexistylous Alpinia, the pollinator behaviour between them strikingly differed with regard to the visit frequency of the pollinators showing a bimodal pattern during the day. This was a better match for the floral behaviour of the flexistylous Alpinia. Some gender differentiation observed between the two types of morphs is also discussed in the present study.     

Pattern of flower size variation along an altitudinal gradient differs between Impatiens textori and Impatiens noli-tangere

Studies of factors influencing spatial variation in flower size offer insights into floral evolution. We investigated altitudinal variations in five flower dimensions of two native Japanese Impatiens species (I. textori and I. noli-tangere) and their interactions with their faunal visitors. These two species have similar floral traits, including flower shape, flowering time, and pollinator species; both species are pollinated mainly by Bombus diversus. In I. textori, all measured flower dimensions were negatively correlated with altitude. In contrast, in I. noli-tangere, no measured flower dimensions correlated with altitude. Thus, the altitudinal pattern of flower size variation differed between these congeneric co-habiting herbaceous plant species. The different patterns suggest that the factors (e.g. altitudinal variations of abiotic factors) that cause variation of flower size differ between these two Impatiens species even though focal species have similar floral traits (e.g. flower shape, flowering time, and pollinator species).     

Morphometric and molecular (RAPD) analysis of six <Emphasis Type="Italic">Serapias</Emphasis> taxa from Croatia

The morphometric analyses and genetic variability assessed by RAPD markers have been used to analyse relations among six Serapias taxa from Croatia (S. istriaca, S. pulae originally described as hybrid, S. ionica, S. vomeracea, S. lingua and S. cordigera). S. istriaca distributed in southern Istria and the island of Lošinj and S. pulae stenoendemic taxon distributed only in southern Istria S. ionica is endemic to the Ionian and Dalmatian islands, while the remaining taxa are more widely distributed. The obtained results shows that the endemic S. istriaca is a well characterised taxon, that S. pulae is a hybrid between S. istriaca and S. lingua and that the hybrid is morphologically and genetically more similar to S. lingua than the second parental species S. istriaca. The division into the subsections Steno-, Medio- and Platypetalae is founded based on the floral morphology while the division into the sections Serapias and Bilamellaria is not evident in the quantitative morphological and genetic analyses. Furthermore, considerable genetic resemblance between S. vomeracea and S. ionica was established.