Chiropterophily in Sinningieae (Gesneriaceae): Sinningia brasiliensis and Paliavana prasinata are bat-pollinated,but P. sericiflora is not. Not yet?

BACKGROUND AND AIMS: Based on the bell shape and greenish colour of the flowers, bat-pollination was suggested for some Sinningieae species (Gesneriaceae). Actually, there are no reports on pollination biology and visitors for these species. This paper reports on pollination biology of Sinningia brasiliensis, Paliavana prasinata and P. sericiflora in south-eastern Brazil. METHODS: Flowers were observed in situ to determine phases of anthesis, colour patterns and scent intensity. Corolla measures were taken from fresh flowers. Nectar production and concentration were measured in flowers bagged at the pre-anthesis phases. Direct visual observations of visitors were made during the day and night, and photographs were taken to analyse their visiting behaviour. KEY RESULTS: Some floral features of the three species fit the bat-pollination syndrome: large, robust and gullet-shaped corollas, colour patterns and large amount of nectar. However, other floral features-such as onset of anthesis, nectar attributes and odour intensity-differ among the species. Nectar volume and total sugar production increased significantly at midnight in S. brasiliensis and P. prasinata, but in P. sericiflora there were no significant differences in the total nectar and sugar production during anthesis. Scent intensity is much higher in S. brasiliensis and P. prasinata than P. sericiflora. Flowers of S. brasiliensis and P. prasinata, whose features fit the chiropterophilous syndrome, are pollinated by glossophagine bat species. Paliavana sericiflora, on the other hand, presents floral features intermediate between bat and hummingbird syndromes, but is visited and pollinated only by hummingbirds. CONCLUSIONS: These data strengthen the statement that the bat syndrome in Sinningieae originated independently in Sinningia brasiliensis and in Paliavana species. Paliavana sericiflora may be another example of a plant 'in transition' from the hummingbird to the bat pollination, but a reversion in the direction of bat to hummingbird might not be excluded. It is also possible that this is a case of speciation on both bat and hummingbird pollination. Studies on Paliavana sister species may provide insights about origins and the evolutionary directions of the pollination systems of these species.     

Phylogenetic relationships in the Gesnerioideae (Gesneriaceae) based on nrDNA ITS and cpDNA trnL-F and trnE-T spacer region sequences

The Gesnerioideae includes most of the New World members of the Gesneriaceae family and is currently considered to include five tribes: Beslerieae, Episcieae, Gesnerieae, Gloxinieae, and Napeantheae. This study presents maximum parsimony and maximum likelihood phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer regions (ITS), and the chloroplast DNA trnL intron, trnL-trnF intergenic spacer region, and trnE-trnT intergenic spacer region sequences. The ITS and cpDNA data sets strongly support the monophyly of a Beslerieae/Napeantheae clade; an Episcieae clade; a Gesnerieae clade; a Gloxinieae clade minus Sinningia, Sinningia relatives, and Gloxinia sarmentiana; and a Sinningia/Paliavana/Vanhouttea clade. This is the first study to provide strong statistical support for these tribes/clades. These analyses suggest that Sinningia and relatives should be considered as a separate tribe. Additionally, generic relationships are explored, including the apparent polyphyly of Gloxinia. Chromosome number changes are minimized on the proposed phylogeny, with the exception of the n = 11 taxa of the Gloxinieae. Scaly rhizomes appear to have been derived once in the Gloxinieae sensu stricto. The number of derivations of the inferior ovary is unclear: either there was one derivation with a reversal to a superior ovary in the Episcieae, or there were multiple independent derivations of the inferior ovary.     

Nectar Sugar Composition in Relation to Pollination Syndromes in Sinningieae (Gesneriaceae)

A putative correlation between nectar sugar composition andpollination syndrome was evaluated in the tribe Sinningieae(Neotropical Gesneriaceae). Sucrose, fructose and glucose werequantified in the nectar of 45 species using high performanceanion-exchange chromatography. Representative species of thehummingbird, bee, bat and moth pollination syndromes were sampledin relation to their numeric importance in the tribe. In hummingbirdand bee flowers, which represent 95% of the species in Sinningieae,nectar was sucrose-dominant (ratio [sucrose]/[hexose] > 1).Sugar ratios below one were only found in the nectar of threespecies with moth and bat syndromes. Sugar concentration averaged23.9 ± 10.6% (wt/total wt) in hummingbird flowers and28.7 ± 10.6% in bee flowers, whereas diluted nectar (7.1± 3.4%) was restricted to bat flowers. Similarities inthe nectar of hummingbird and bee flowers contrast with thepresence of specific morphological traits associated with thesetwo syndromes, indicating that plant-pollinator relationshipsrely on flower display rather than on nectar characteristics.By contrast, distinct nectar chemistry is correlated with thebat syndrome in which a particularly low sucrose productionis responsible for hexose dominance. Copyright 2001 Annals ofBotany Company Nectar sugar composition, pollination syndrome, Sinningia, Gesneriaceae, Brazil     

Non-Euglossine bees also function as pollinators of Sinningia species (Gesneriaceae) in southeastern brazil

Pollination by male and female Euglossini bees, euglossophily, was suggested for a number of neotropical Gesneriaceae species. Information on bee species other than Euglossini as pollinators of neotropical members of this family is limited, and in the tribe Sinningieae data about bee pollination are still lacking. Here, we report on floral biology and bee pollination of four Sinningia species: S. schiffneri, S. eumorpha, S. villosa, and Sinningia "canastrensis". The flower features, such as corolla size, shape, and colour, are very different among the four species, but all conform to the melittophilous syndrome. The average nectar volume and sugar amount is low in S. schiffneri, S. eumorpha, and Sinningia "canastrensis", when compared to that of S. villosa, but low nectar amounts is a general feature of Sinningia species. The main pollinators of the four species are: small Tapinotaspidini (Trigonopedia ferruginea) of S. schiffneri, large Bombini (Bombus morio) and large Centridini (Epicharis morio) of S. eumorpha, large Euglossini (Eulaema cingulata and Eufriesea surinamensis) of S. villosa, and large Euglossini (Eufriesea violascens) and Megachilini (Megachile sp.) of Sinningia "canastrensis". Out of the four species, only S. villosa is exclusively Euglossini-pollinated. The marked differences in flower features and nectar production of these Sinningia species may reflect their pollination by distinct groups of bees. These results strengthen the idea of multiple origins for the pollination systems involving bees within this genus, which is highly supported by molecular phylogenetic analyses.     

Testing the regeneration niche hypothesis with Gesneriaceae (tribe Sinningiae) in Brazil: Implications for the conservation of rare species

The germination requirements of sexually reproducing plants are regulated by environmental factors such as temperature. Those factors acting at the germination phase are part of the regeneration niche, which is fundamental in the processes that contribute to habitat suitability and geographic distribution. We tested the hypothesis that rarity is associated with regeneration niche in three species of plants in the family Gesneriaceae (tribe Sinningieae), Sinningia rupicola (Mart.) Wiehler, Paliavana sericiflora Benth and Sinningia allagophylla (Mart.) Wiehler, which vary in their distribution and habitat specificity but share a small zone of sympatry in rocky fields south of Belo Horizonte in Minas Gerais, Brazil. The regeneration niche was tested using a seed germination experiment under controlled light conditions at seven fixed temperatures (10–40°C at 5°C intervals). Each of the three species germinated differently at the various temperatures. The species with the smallest geographic range, S. rupicola, also had the most restricted germination: germination peaked at 15°C when relatively few seeds germinated (45%), and even fewer germinated at other temperatures. The regeneration niche was wider in P. sericiflora and wider still in S. allagophylla, with germination greater than 90% between 15–25°C and greater than 80% between 15–30°C, respectively. Our germination results provide qualified support for the hypothesis of correlation of the regeneration niche with geographic distribution of related plant taxa, with important conservation implications for rare and endangered species.     

Constrained lability in floral evolution: counting convergent origins of hummingbird pollination in Penstemon and Keckiella

In the clade of Penstemon and segregate genera, pollination syndromes are well defined among the 284 species. Most display combinations of floral characters associated with pollination by Hymenoptera, the ancestral mode of pollination for this clade. Forty-one species present characters associated with hummingbird pollination, although some of these ornithophiles are also visited by insects. The ornithophiles are scattered throughout the traditional taxonomy and across phylogenies estimated from nuclear (internal transcribed spacer (ITS)) and chloroplast DNA (trnCD/TL) sequence data. Here, the number of separate origins of ornithophily is estimated, using bootstrap phylogenies and constrained parsimony searches. Analyses suggest 21 separate origins, with overwhelming support for 10 of these. Because species sampling was incomplete, this is probably an underestimate. Penstemons therefore show great evolutionary lability with respect to acquiring hummingbird pollination; this syndrome acts as an attractor to which species with large sympetalous nectar-rich flowers have frequently been drawn. By contrast, penstemons have not undergone evolutionary shifts backwards or to other pollination syndromes. Thus, they are an example of both striking evolutionary lability and constrained evolution.     

Distribution and Flowering Ecology of Bromeliads along Two Climatically Contrasting Elevational Transects in the Bolivian Andes1

We compared the diversity, taxonomic composition, and pollination syndromes of bromeliad assemblages and the diversity and abundance of hummingbirds along two climatically contrasting elevational gradients in Bolivia. Elevational patterns of bromeliad species richness differed noticeably between transects. Along the continuously wet Carrasco transect, species richness peaked at mid‐elevations, whereas at Masicurí most species were found in the hot, semiarid lowlands. Bromeliad assemblages were dominated by large epiphytic tank bromeliads at Carrasco and by small epiphytic, atmospheric tillandsias at Masicurí. In contrast to the epiphytic taxa, terrestrial bromeliads showed similar distributions across both transects. At Carrasco, hummingbird‐pollination was the most common pollination mode, whereas at Masicurí most species were entomophilous. The proportion of ornithophilous species increased with elevation on both transects, whereas entomophily showed the opposite pattern. At Carrasco, the percentage of ornithophilous bromeliad species was significantly correlated with hummingbird abundance but not with hummingbird species richness. Bat‐pollination was linked to humid, tropical conditions in accordance with the high species richness of bats in tropical lowlands. At Carrasco, mixed hummingbird/bat‐pollination was found especially at mid‐elevations, i.e., on the transition between preferential bat‐pollination in the lowlands and preferential hummingbird‐pollination in the highlands. In conclusion, both richness patterns and pollination syndromes of bromeliad assemblages varied in distinct and readily interpretable ways in relation to environmental humidity and temperature, and bromeliad pollination syndromes appear to follow the elevational gradients exhibited by their pollinators.     

基于13 个内含子的序列探讨鲸目的系统发育关系

本文基于实验室筛选得到的13 对内含子标记,在鲸偶蹄目的15 个物种中进行有效扩增,并重建了这15
个物种的系统发育关系。结果表明,抹香鲸总科(Physeteroidea) 位于齿鲸亚目(Odontoceti)的基部,从而支
持了传统的齿鲸亚目的单系性。在海豚总科(Delphinoidea)内部,贝斯分析结果支持了鼠海豚科(Phocoenidae)
和一角鲸科(Monodontidae)的姐妹群关系,而后再与海豚科(Delphinidae)相聚。系统发育分析同时还
强烈支持了海豚科的四个属(Sousa,Tursiops,Stenella,Delphinus)组成一个单系的“复合体”。另外,我们的分
析结果并不支持瓶鼻海豚属(Tursiops)和原海豚属(Stenella)的单系性。基于松散分子钟的分歧时间估算与以
往文献中的结果没有明显差异。这些研究结果提示,核基因内含子序列有希望解决一些长期存在的鲸类系统发
育问题。     

Repeated evolution of vertebrate pollination syndromes in a recently diverged Andean plant clade

Although specialized interactions, including those involving plants and their pollinators, are often invoked to explain high species diversity, they are rarely explored at macroevolutionary scales. We investigate the dynamic evolution of hummingbird and bat pollination syndromes in the centropogonid clade (Lobelioideae: Campanulaceae), an Andean‐centered group of ∼550 angiosperm species. We demonstrate that flowers hypothesized to be adapted to different pollinators based on flower color fall into distinct regions of morphospace, and this is validated by morphology of species with known pollinators. This supports the existence of pollination syndromes in the centropogonids, an idea corroborated by ecological studies. We further demonstrate that hummingbird pollination is ancestral, and that bat pollination has evolved ∼13 times independently, with ∼11 reversals. This convergence is associated with correlated evolution of floral traits within selective regimes corresponding to pollination syndrome. Collectively, our results suggest that floral morphological diversity is extremely labile, likely resulting from selection imposed by pollinators. Finally, even though this clade's rapid diversification is partially attributed to their association with vertebrate pollinators, we detect no difference in diversification rates between hummingbird‐ and bat‐pollinated lineages. Our study demonstrates the utility of pollination syndromes as a proxy for ecological relationships in macroevolutionary studies of certain species‐rich clades.     

Ancestral reconstruction of flower morphology and pollination systems in Schizanthus (Solanaceae)

Concerted changes in flower morphology and pollinators provide strong evidence on adaptive evolution. Schizanthus (Solanaceae) has zygomorphic flowers and consists of 12 species of annual or biennial herbs that are distributed mainly in Chile and characterized by bee-, hummingbird-, and moth-pollination syndromes. To infer whether flowers diversified in relation to pollinator shifts, we traced the evolutionary trajectory of flower traits and visitors onto a phylogeny based on sequence data from ITS, waxy, and trnF/ndhJ DNA. Maximum-likelihood ancestral reconstruction of floral traits suggests that ancestral Schizanthus had a bee-pollination syndrome. The hummingbird syndrome evolved in S. grahamii, a high elevation species in the Andes. The moth syndrome evolved in the ancestor of three species that inhabit the Atacama Desert. Results of mapping flower visitors onto the phylogeny show that the shift from bee to hummingbird pollination concurred with a shift in pollinators as predicted by the syndromes. However, the same pattern was not found for the moth syndrome. Visits by moths were observed only in one of the three moth-syndrome species, and at a very low rate. This mismatch suggests either anachronic floral characters or maintenance of rare, imperceptible moth pollination backed up by capacity for autonomous selfing. Overall, results suggest that diversification of flower traits in Schizanthus has occurred in relation to pollinator shifts.     

Obligatory group I introns with unusual features at positions 1949 and 2449 in nuclear LSU rDNA of Didymiaceae myxomycetes

Myxomycetes (plasmodial slime molds) belonging to the order Physarales contain obligatory group I introns at positions 1949 and 2449 in their large subunit ribosomal RNA gene. Here, we report 36 group I introns from the Didymiaceae family (order Physarales) from 18 isolates representing three genera and seven species, and have reconstructed both host and intron phylogenies. The introns, named L1949 and L2449, were found in all isolates analyzed, consistent with an obligatory distribution in Didymiaceae. The introns fold at the RNA-level into typical group I ribozyme core structures that are relatively conserved, but contain large and highly variable extension sequences in peripheral domains without any detectable protein coding capacities. Furthermore, the L1949 and L2449 introns have probably become dependent on host factors for folding or activity. This assumption is based on that all introns tested for self-splicing in vitro failed to ligate the flanking exon regions. Phylogenies based on LSU rDNA and intron sequences are consistent with that the L1949 and L2449 introns follow a strict vertical inheritance within Didymiaceae. We suggest that the Didymiaceae L1949 and L2449 introns are well suited as high-resolution markers in genetic assessments at various taxonomic levels, from closely related strains of a single species to separating genera.     

地衣型真菌的I型内含子及其在系统发育中的应用

以蜈蚣衣属、黑蜈蚣衣属地衣样品为材料,结合GenBank中相关数据,对地衣型真菌核糖体小亚基 DNA上的I型内含子分布模式进行归纳,并探讨了其在地衣型真菌系统发育研究中的应用。结果表明在地衣型真菌核糖体小亚基 DNA上存在多个I型内含子插入位点,通过二级结构分析给出了天然状态下I型内含子发生转座的证据。分析显示,I型内含子作为分子标记,只适合用于种下单位的系统发育研究中。     

The assembly of plants used as nectar sources by hummingbirds in a Cerrado area of Central Brazil

Studies on hummingbird–plant interactions commonly use a pollination approach emphasizing mutualistic relationships. But floral resources are often used opportunistically by these birds. Plant–pollinator assemblies and pollination sustainability will depend both on the well-adapted plants and other potential floral resources. The Cerrado, Neotropical savannas of Central Brazil, has ca. 7.5 % of its flora supposedly adapted to hummingbird pollination. But detailed information about flowers effectively used by hummingbirds at community level is still lacking. Hence, we recorded all plant species visited by hummingbirds, to determine how these nectariferous flowers were distributed in time and space in different plant formations of a Cerrado area, and also the hummingbird species that visit them. The study was conducted between March 2007 and December 2008 in the Panga Ecological Station. Data regarding flowering phenology, floral morphology and visitation were collected monthly. Forty-six nectariferous species from 39 genera and 17 families were recorded, most with annual flowering dynamics and tubular flowers. But only 21 species had a combination of traits fitting classic ornithophilous syndrome. For the remaining species hummingbird visitation was ascertained from observations at the study site or other sites in the region. Eight hummingbird species occurred in the area and were recorded visiting directly 36 plant species. The study area presented a relatively low number of ornithophilous plants, but a great habitat diversity and many non-ornithophilous plants that hummingbirds used as nectar sources. Therefore, in the studied Cerrado, the diversity of environments and nectariferous plants favour the maintenance of resident and migrant hummingbirds.     

Phylogenetic relationships of the African bush-shrikes and helmet-shrikes (Passeriformes: Malaconotidae)

The African bush-shrikes and helmet-shrikes (Malaconotidae sensu [A Complete Checklist of the Birds of the World, third ed., Helm Editions, London, 2003]) include 10 genera and 52 species of predatory passerine birds for which monophyly, sister-group, and inter-generic relationships are disputed. To resolve their relationships, we analyzed 2313 bp of sequence data obtained from two nuclear introns (myoglobin intron-2, beta-fibrinogen intron-5) and a mitochondrial protein-coding gene (ND2) using parsimony, maximum likelihood, and Bayesian inference. A strongly supported clade that included representatives of the Malaconotidae, Platysteiridae, and Vangidae was found in all analyses. Three main groups emerged within this clade but relationships between these three groups were always poorly supported. The first group included the helmet-shrikes (Prionops), flycatcher-shrikes (Bias and Megabyas), and vangas (Cyanolanius and Pseudobias), currently placed in the families Malaconotidae, Platysteiridae, and Vangidae, respectively. The second group consisted of four Platysteiridae genera (Lanioturdus, Batis, Platysteira, and Dyaphorophyia), with the remaining Malaconotidae genera ('core malaconotids') forming the last group. Two main clades emerged within the 'core malaconotids,' with the position of the genus Nilaus being variable. The first clade included Malaconotus, Dryoscopus, Bocagia, and Tchagra and the second Chlorophoneus, Laniarius, Rhodophoneus, and Telophorus. Monophyly of the genus Chlorophoneus was never recovered, a result that is consistent with morphological data.     

AFLP phylogeny of Mimulus section Erythranthe and the evolution of hummingbird pollination

Abstract.— Species in Mimulus section Erythranthe (monkeyflowers) have become model systems for the study of the genetic basis of ecological adaptations. In this study, we pursued two goals. First, we reconstructed the phylogeny of species in Erythranthe using both DNA sequences from the ribosomal DNA ITS and ETS and AFLPs. Data from rDNA sequences support the monophyly of the section, including M. parishii, but provide little support for relationships within it. Analyses using AFLP data resulted in a well-supported hypothesis of relationships among all Erythranthe species. Our second goal was to reconstruct ancestral pollination syndromes and ancestral states of individual characters associated with hummingbird-pollinated flowers. Both parsimony and likelihood approaches indicate that hummingbird pollination evolved twice in Erythranthe from insect-pollinated ancestors. Our reconstruction of individual characters indicates that corolla color and some aspects of corolla shape change states at the same point on the phylogenetic tree as the switch to hummingbird pollination; however, a switch to secretion of high amounts of nectar does not. Floral trait transformation may have been more punctuational than gradual.     

Quantifying hummingbird preference for floral trait combinations: The role of selection on trait interactions in the evolution of pollination syndromes

Darwin recognized the flower's importance for the study of adaptation and emphasized that the flower's functionality reflects the coordinated action of multiple traits. Here we use a multitrait manipulative approach to quantify the potential role of selection acting on floral trait combinations underlying the divergence and maintenance of three related North American species of Silene (Caryophyllaceae). We artificially generated 48 plant phenotypes corresponding to all combinations of key attractive traits differing among the three Silene species (color, height, inflorescence architecture, flower orientation, and corolla‐tube width). We quantified main and interaction effects of trait manipulation on hummingbird visitation preference using experimental arrays. The main effects of floral display height and floral orientation strongly influenced hummingbird visitation, with hummingbirds preferring flowers held high above the ground and vertically to the sky. Hummingbirds also prefer traits in a nonadditive manner as multiple two‐way and higher order interaction effects were important predictors of hummingbird visitation. Contemporary trait combinations found in hummingbird pollinated S. virginica are mostly preferred. Our study demonstrates the likelihood of pollination syndromes evolving due to selection on trait combinations and highlights the importance of trait interactions in understanding the evolution of complex adaptations.     

An Assemblage of Hummingbird-pollinated Flowers in a Montane Forest in Southeastern Brazil

Relationships between ornithophilous flowers and hummingbirds have been little studied in southern South America, where hummingbird species richness is low. We studied an ornithophilous flower assemblage and the hummingbird pollinators in a montane forest in southeastern Brazil. Twenty-three native hummingbird-pollinated plant species in 21 genera and 14 families were observed. Bromeliaceae, Fabaceae, Gesneriaceae, and Lobeliaceae are represented by more than one species within the assemblage. Flower shapes vary from narrow tube to bowl-shape, but tubular flowers prevail. The variety of flower shapes and sizes results in diverse pollen placement on the body parts of hummingbird visitors, although pollen is deposited mostly on the bill. Sugar concentration in nectar averages 22.1%, and nectar volume per flower averages 16.9 μl. The plant populations bloom for one month to year-round, and their flowering approaches the steady-state pattern. Four flower subsets may be defined within the assemblage, each subset related to the bill size and foraging habits of the most frequent bird visitor. Of the six species of hummingbirds recorded at the study site, four are common and largely resident. The four hummingbirds differ in bill size, body mass, and favoured foraging sites, attributes which reflect their favoured flower subsets. One hermit and one trochiline hummingbird share most of the flower species they use, these two birds being the major pollinators within the flower assemblage. This montane forest community may be viewed as medium-rich in ornithophilous flower species and poor in hummingbird species.     

Phylogeny of the parasitic plant family Orobanchaceae inferred from phytochrome A

Partial sequences of the nuclear gene encoding the photoreceptor phytochrome A (PHYA) are used to reconstruct relationships within Orobanchaceae, the largest of the parasitic angiosperm families. The monophyly of Orobanchaceae, including nonphotosynthetic holoparasites, hemiparasites, and nonparasitic Lindenbergia is strongly supported. Phytochrome A data resolve six well-supported lineages that contain all of the sampled genera except Brandisia, which is sister to the major radiation of hemiparasites. In contrast to previous plastid and ITS trees, relationships among these major clades also are generally well supported. Thus, the robust phylogenetic hypothesis inferred from the PHYA data provides a much better context in which to evaluate the evolution of parasitism within the group. Ninety-eight species of Orobanchaceae, representing 43 genera, are included and Brandisia, Bungea, Cymbaria, Esterhazya, Nesogenes, Phtheirospermum, Radamaea, Siphonostegia, and Xylocalyx are confirmed as members of Orobanchaceae. The earliest diverging lineage of hemiparasites is identified for the first time; it contains Bungea, Cymbaria, Monochasma, Siphonostegia, and the monotypic Schwalbea, which is federally endangered. This basal clade is marked by the presence of two novel introns. A second, apparently independent gain of one of these introns marks a clade of largely European taxa. There is significant rate heterogeneity among PHYA sequences, and the presence of multiple PHYA in some taxa is consistent with observed ploidy levels.     

The geographical pattern of speciation and floral diversification in the neotropics: the tribe sinningieae (gesneriaceae) as a case study

The geographical pattern of speciation and the relationship between floral variation and species ranges were investigated in the tribe Sinningieae (Gesneriaceae), which is found mainly in the Atlantic forests of Brazil. Geographical distribution data recorded on a grid system of 0.5 x 0.5 degree intervals and a near-complete species-level phylogenetic tree of Sinningieae inferred from a simultaneous analysis of seven DNA regions were used to address the role of geographical isolation in speciation. Geographical range overlaps between sister lineages were measured across all nodes in the phylogenetic tree and analyzed in relation to relative ages estimated from branch lengths. Although there are several cases of species sympatry in Sinningieae, patterns of sympatry between sister taxa support the predominance of allopatric speciation. The pattern of sympatry between sister taxa is consistent with range shifts following allopatric speciation, except in one clade, in which the overlapping distribution of recent sister species indicates speciation within a restricted geographical area and involving changes in pollinators and habitats. The relationship between floral divergence and regional sympatry was also examined by analyzing floral contrasts, phenological overlap, and the degree of sympatry between sister clades. Morphological contrast between flowers is not increased in sympatry and phenological divergence is more apparent between allopatric clades than between sympatric clades. Therefore, our results failed to indicate a tendency for sympatric taxa to minimize morphological and phenological overlap (geographic exclusion and/or character displacement hypotheses). Instead, they point toward adaptation in phenology to local conditions and buildup of sympatries at random with respect to flower morphology. Additional studies at a lower geographical scale are needed to identify truely coexisting species and the components of their reproductive isolation.     

Molecular Systematics and Evolution of the Growth Hormone Introns in the Salmoninae

DNA sequence data was collected for the C and D introns in the duplicate growth hormone loci (GH1 and GH2) from Brachmystax lenok, two subspecies of Hucho hucho, Hucho (Parahucho) perryi, Salmo salar, Salmo trutta, Acantholingua ohridana (Salmothymus), six species of Salvelinus, eight species of Oncorhynchus including O. masou, and three outgroups including Thymallus thymallus, Coregonus artedi, and Coregonus clupeaformis. Phylogenetic analyses were performed using maximum parsimony and maximum likelihood (PAUP, version 4.08beta) with gaps as missing data and as a fifth base. B. lenok was basal in all of the trees and all of the other genera were monophyletic with the exception that A. ohridana always placed within Salmo, and H. hucho sp. often placed with B. lenok. The GH1 introns supported a sister relationship between Oncorhynchus and Salvelinus, while the combined GH2 introns were ambiguous at this node. This result contrasts with trees based on morphology and the ribosomal ITS1 sequences that support a sister relationship between Salmo and Oncorhynchus. The only estrogen response element (ERE) in the gene is found in the C intron and has mutated in GH2 in all of the species except B. lenok. The ERE element in GH1 has undergone another mutation in all of the species except for B. lenok, and members of the two genera Salvelinus and Oncorhynchus. Thus these latter two genera are the only ones with a difference in expression of GH1 and GH2 in the presence of estrogen. Differences in selective pressure on the introns in the duplicate genes in different taxa could account for the conflicting results obtained in the phylogenetic analysis.