Description, seasonal morphological variation, and molecular identification of Paraxanthus barbiger megalopae obtained from the natural environment

Larval identification represents a powerful tool for detailed studies on recruitment and population dynamics in marine invertebrates. However, intra-specific morphological variation can become a serious limitation for the correct identification at species level. High morphological variation can be expected in species with continuous breeding periods because larvae are exposed to seasonal fluctuations in physical and biological factors during their development in the plankton. We describe, for the first time, the megalopae of Paraxanthus barbiger, one of the most common and abundant brachyuran crabs along the coast of Chile. To validate larvae identification, the 16S rRNA gene was sequenced from both megalopae and adults, and was compared with sequences of three sympatric species. In addition, size, body shape, and appendage setation pattern variations were analyzed with a year-round sampling scheme. The results demonstrated high seasonal phenotypic plasticity in size. Despite these differences, certain conservative characteristics exist which can be very useful for identification at species level.     

Freshwater sponge (Porifera: Spongillidae) distribution across a landscape: Environmental tolerances,habitats, and morphological variation

Freshwater sponges are important to ecosystem functioning; however, information about their biogeography and interspecific variation is fragmentary, limiting our ability to assess their role. Although the specific epithets of two common species suggest that sponges found in lentic habitats are Spongilla lacustris, and those found in lotic habitats are Ephydatia fluviatilis, the number of sponge species in the UK is unresolved. We sampled sponges in a variety of habitats and used both morphological and molecular (D3 domain of 28S rDNA) methods to identify six species, including the first record of Trochospongilla horrida. We contrasted species in terms of their environmental tolerances, habitats, and variation, and we expanded on the limited information available about the geographic distributions of these sponges. In our study, most sponge species colonized a variety of substrates, but exhibited different distributions. The most widespread sponge, S. lacustris, was present at lower mean water temperatures and was more often located above a latitude of 55°N. Ephydatia fluviatilis was the most common species in rivers, but was also located in lentic habitats. Salinity in anthropogenic habitats was not a significant factor for the presence of E. fluviatilis or the more patchily distributed species Eunapius fragilis. Instead, these species occurred more frequently at sites with negative oxidation–reduction potential. Sponge biodiversity may be affected by substrate availability in anthropogenic habitats, invasive species, and improved ability to recognize sponge taxa. Crucially, we provide foundation data as a prerequisite for future ecological evaluation.     

Rapid Morphological Changes in Threespine Stickleback, Gasterosteus aculeatus, in Freshwater

Synopsis Freshwater and marine threespine stickleback, Gasterosteus aculeatus, differ remarkably in armour plate number and body shape, although differences in other morphological characters are also common. Most freshwater populations have apparently evolved after isolation of marine sticklebacks in freshwater. After colonisation of freshwater habitats, they show rapid morphological changes and associated genetic isolation within as few as eight generations. I transferred fish from marine tide pools to two isolated freshwater ponds, differing in habitat characteristics, at the beginning of the breeding season, when females had ripe ovaries and males had breeding coloration. The first generation fish that I sampled from the ponds had significantly fewer armour plates than their marine ancestors and differed in shape. I also found some significant differences between fish sampled from the larger pond and those from a smaller, adjacent pond. This extremely rapid morphological divergence suggests that either the marine sticklebacks were highly phenotypically plastic or that there was very strong natural selection acting on the first generation within freshwater habitats.     

Morphological divergence of North‐European nine‐spined sticklebacks (Pungitius pungitius): signatures of parallel evolution

Parallel evolution is characterised by repeated, independent occurrences of similar phenotypes in a given habitat type, in different parts of the species distribution area. We studied body shape and body armour divergence between five marine, four lake, and ten pond populations of nine‐spined sticklebacks [Pungitius pungitius (Linnaeus, 1758)] in Fennoscandia. We hypothesized that marine and lake populations (large water bodies, diverse fish fauna) would be similar, whereas sticklebacks in isolated ponds (small water bodies, simple fish fauna) would be divergent. We found that pond fish had deeper bodies, shorter caudal peduncles, and less body armour (viz. shorter/absent pelvic spines, reduced/absent pelvic girdle, and reduced number of lateral plates) than marine fish. Lake fish were intermediate, but more similar to marine than to pond fish. Results of our common garden experiment concurred with these patterns, suggesting a genetic basis for the observed divergence. We also found large variation among populations within habitat types, indicating that environmental variables other than those related to gross habitat characteristics might also influence nine‐spined stickleback morphology. Apart from suggesting parallel evolution of morphological characteristics of nine‐spined sticklebacks in different habitats, the results also show a number of similarities to the evolution of three‐spined stickleback (Gasterosteus aculeatus Linnaeus, 1758) morphology. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 403–416.     

Morphological plasticity and ecophysiological response of ground ivy (Glechoma hederacea,Lamiaceae) in contrasting natural habitats within its native range

Abstract

Some species intrinsically have a high invasiveness capacity, shown by high phenotypic plasticity and rapid growth, enabling a wide distribution across their native habitats and successful invasion in the introduced range. For such species, information from native habitats is critically important. An example is Glechoma hederacea, native to Eurasia but introduced and widespread in the USA. Our main objective was to investigate variation in traits of native G. hederacea populations across contrasting habitats: open, forest edge and understory. Vegetation was sampled and the ecophysiological and morphological traits were measured with accompanying environmental parameters. Results showed that in native habitats environmental conditions cover wide gradients of light and soil moisture. Plants had the highest cover in nutrient-rich, shaded habitats, representing the optimal habitat, indicating shade tolerance of G. hederacea. Plants from forest understory exhibited strong similarities in investigated traits to plants from the forest edge, even though this was a drier, sunnier habitat. Plants from open, sunny habitats experienced stress as indicated by the quantum efficiency of PSII and significantly higher sexual reproduction. Results show that G. hederacea is moderately tolerant simultaneously to shade and drought, a characteristic that has been reported for numerous invasive species, while at the same time it shares some characteristics with weedy plants.     

Land masses and oceanic currents drive population structure of Heritiera littoralis,a widespread mangrove in the Indo‐West Pacific

Phylogeographic forces driving evolution of sea‐dispersed plants are often influenced by regional and species characteristics, although not yet deciphered at a large spatial scale for many taxa like the mangrove species Heritiera littoralis. This study aimed to assess geographic distribution of genetic variation of this widespread mangrove in the Indo‐West Pacific region and identify the phylogeographic factors influencing its present‐day distribution. Analysis of five chloroplast DNA fragments’ sequences from 37 populations revealed low genetic diversity at the population level and strong genetic structure of H. littoralis in this region. The estimated divergence times between the major genetic lineages indicated that glacial level changes during the Pleistocene epoch induced strong genetic differentiation across the Indian and Pacific Oceans. In comparison to the strong genetic break imposed by the Sunda Shelf toward splitting the lineages of the Indian and Pacific Oceans, the genetic differentiation between Indo‐Malesia and Australasia was not so prominent. Long‐distance dispersal ability of H. littoralis propagules helped the species to attain transoceanic distribution not only across South East Asia and Australia, but also across the Indian Ocean to East Africa. However, oceanic circulation pattern in the South China Sea was found to act as a barrier creating further intraoceanic genetic differentiation. Overall, phylogeographic analysis in this study revealed that glacial vicariance had profound influence on population differentiation in H. littoralis and caused low genetic diversity except for the refugia populations near the equator which might have persisted through glacial maxima. With increasing loss of suitable habitats due to anthropogenic activities, these findings therefore emphasize the urgent need for conservation actions for all populations throughout the distribution range of H. littoralis.     

Species boundaries,phylogenetic relationships,and ecological differentiation inAnthriscus (Apiaceae)

Species boundaries and phylogenetic relationships of 17 taxa ofAnthriscus (Apiaceae), with special emphasis on the critical sect.Cacosciadium, were explored using morphological data with principal component analysis, phenetics, and phylogenetics. The analyses did not provide satisfactory resolution of taxa from sect.Cacosciadium and only four species were retained. The total number of species was reduced to nine. Sect.Cacosciadium is distinguished by only two synapomorphies while sects.Anthriscus andCaroides are better supported. Present geographic and ecological variation suggests that the radiation ofAnthriscus occurred through divergence of peripheral isolated populations adapting to different habitats: high montane meadows and screes, shady climax forests, and seasonally dry habitats at lower altitudes. The adaptive significance of particular morphological traits is discussed.     

Floral morphology and reproductive success in the orchid Epipactis helleborine: regional and local across-habitat variation

 The terrestrial orchid Epipactis helleborine is a morphologically variable species with a wide distribution in Europe. It is pollinated by social wasps, and most populations show the morphological characteristics of outcrossing species. However, local predominantly selfing subspecies and varieties have been documented from drier habitats. To document geographic variation in floral morphology, ability to produce seeds through autogamy, and reproductive success in E. helleborine, we sampled 13 populations from three geographic regions along a latitudinal gradient of c. 1000 km from northern to southern Sweden. In the southernmost region, populations in dry and mesic habitats were compared. Supplemental hand-pollination was conducted to determine whether among-population variation in fruit set could be explained by differences in the natural level of pollination, and whether any relationship between floral morphology and fruit production could be explained by interactions with pollinators. Bagging experiments showed no evidence of autogamy in any of the study populations. Number of flowers, pollinia removal and fruit set varied significantly among populations but did not differ among regions. Pollinia removal was positively correlated with population size and both pollinia removal and fruit set were lower in dry than in mesic habitats. At the level of the individual plant, the number of pollinia removed increased more rapidly with flower number than did number of fruits produced. The hand-pollination experiment indicated that the positive relationship between number of flowers and fruit production was due to a higher degree of pollen limitation in plants with few flowers than in plants with many flowers. The experiment also showed that variation in the level of pollen limitation could only partly explain variation in fruit set among populations. Received November 6, 2001; accepted April 27, 2002 Published online: December 3, 2002     

Morphology and ecology of Oblea rotunda (Diplopsalidaceae,Dinophyceae) from a new habitat: a brackish and hypertrophic ecosystem,the Étang de Bolmon (South of France).

A small thecate dinoflagellate was encountered during winter and spring in the phytoplankton community of a shallow, brackish and hypertrophic pond in the South of France. The abundance of material permitted its identification, using scanning electron microscopy, as Oblea rotunda Balech ex Sournia. However, morphological features showed some discrepancies with the typical characteristics of O. rotunda. Environmental hydrographic parameters in the pond were very different from marine ecosystems where O. rotunda is usually reported. In this polluted and alkaline pond, salinity was low, ranging from 1.1 to 6.2 p.s.u.; the maximum densities of O. rotunda (greater than 1?×?10⁵ cells l^???1) were observed at temperatures around 13°C, after a Cylindrotheca closterium?–?Heterocapsa rotundata bloom in early spring. These two species and other abundant taxa of the phytoplankton had seasonal patterns that could explain the presence of O. rotunda, since they could have been a food for this heterotrophic species. As this population showed most of the morphological criteria of O. rotunda, but with some variability and a different ecology, it is better considered as a variant of the marine species, rather than as a new species. This study provides additional data on the ecological and morphological features of this poorly known small peridinioid species, previously only reported from open seas and oceans.     

Ecomorphological variation and sexual dimorphism in a recent radiation of dwarf chameleons (Bradypodion)

Natural selection tends to favour optimal phenotypes either through directional or stabilizing selection; however, phenotypic variation in natural populations is common and arises from a combination of biotic and abiotic interactions. In these instances, rare phenotypes may possess a fitness advantage over the more common phenotypes in particular environments, which can lead to adaptation and ecological speciation. A recently radiated clade of dwarf chameleons (Bradypodion) restricted to southern KwaZulu‐Natal Province, South Africa, is currently comprised of two species (Bradypodion melanocephalum and Bradypodion thamnobates), yet three other phenotypic forms exist, possibly indicating the clade is far more speciose. Very little genetic differentiation exists between these five phenotypic forms; however, all are allopatric in distribution, occupy different habitats and vary in overall size and coloration, which may indicate that these forms are adapting to their local environments and possibly undergoing ecological speciation. To test this, we collected morphometric and habitat data from each form and examined whether ecological relevant morphological differences exist between them that reflect their differential habitat use. Sexual dimorphism was detected in four of the five forms. Yet, the degree and number of dimorphic characters was different between them, with size‐adjusted male‐biased dimorphism being much more pronounced in B. thamnobates. Habitat differences also existed between sexes, with males occupying higher perches in more closed canopy (forested) habitats than females. Clear morphological distinctions were detected between four of the five forms, with the head explaining the vast majority of the variation. Chameleons occupying forested habitats tended to possess proportionally larger heads and feet but shorter limbs than those in open canopy habitats (i.e. grassland). These results show that this species complex of Bradypodion is morphologically variable for traits that are ecologically relevant for chameleons, and that the variation among the five phenotypic forms is associated with habitat type, suggesting that this species complex is in the early stages of ecological speciation. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 113–130.     

Phenotypic plasticity and morphological adaptation of Halimeda opuntia (Bryopsidales,Chlorophyta) to light intensity

Plasticity gives plants the ability to adapt their morphology and growth to various environments. Environmental factors can lead to changes in the growth forms of algae. Halimeda opuntia was used as a model organism to determine the effects of highly irradiated and shade conditions in the field and its responses to low light conditions in the laboratory, which are known to be some of the main factors driving its morphological plasticity. To investigate the morphological and anatomical characteristics of the species, a total of 61 characteristics and 54 samples from Thailand, Japan and Indonesia were examined. In addition, we also tested the response under different light conditions in the laboratory. A phylogenetic tree was constructed using the tufA marker to confirm the species identification. We found that the thallus forms, branching patterns and segment shapes and sizes responded to the different light conditions. A brittle thallus network was found under shade conditions with low light intensity, while a compact thallus form was found under highly irradiated conditions. The H. opuntia segment shape was reniform under highly irradiated conditions, but its segments were adapted to be deeply trilobed in the lower thallus and tripartite shape in the upper thallus under shade conditions. The segment size also adapted; the segments in shaded areas were longer than those in sunny areas, which might have helped them increase their thallus height to ensure exposure to the high light habitat. This morphological variation and plasticity expanded our understanding of the range of H. opuntia plasticity present in the field and could help explain why this species is common and successfully colonizes various habitats worldwide.     

Multivariate analysis of morphological and anatomical characters of Calophyllum (Calophyllaceae) in South America

Calophyllum (Calophyllaceae), previously placed in Clusiaceae, is easily recognizable by its opposite entire leaves with close parallel venation alternating with resin canals. However, distinction between species has been difficult, because of infraspecific variation in tepal and stamen number and resemblance among species that share similar habitats. Here, I report the results of multivariate analyses of morphological and anatomical characters for Calophyllum in South America, and provide a taxonomic treatment for the genus in South America, the first since that of Vesque in 1893. Thirteen preliminary morphogroups were identified. Thirty‐two morphological characters of the leaf, flower and fruit from 401 specimens, and 17 anatomical leaf characters from 45 specimens were measured and analysed using principal component analyses (PCAs) and discriminant analyses (DAs). PCAs were used to find groups and DAs were used to validate those PCAs that were potential groups. Two main subgroups were identified in the general analysis. Subgroup M1 has terete stems and smaller leaves and flowers than subgroup M2, which, instead, has quadrangular stems. Only subgroup M2 showed distinctive clusters in regional and local analyses. Distinctive clusters and morphological and anatomical characters helped us to recognize four species in South America, including a new species, Calophyllum pubescens sp. nov. . In addition, a new species, Calophyllum mesoamericanum sp. nov. , is described from Central America. © 2013 The Linnean Society of London,     

SEED GERMINATION TIMING PATTERNS IN INTERMOUNTAIN PENSTEMON (SCROPHULARIACEAE)

Regulation of seed germination timing is an important component of population persistence, especially for short-lived plants in seasonal environments with unpredictable year-to-year weather variation. Seed germination patterns were examined in the laboratory for seeds from 135 populations belonging to 38 species and 13 sections of the genus Penstemon (Scrophulariaceae), from habitats ranging from warm desert to alpine tundra. Seeds of most species were dormant at dispersal and required a period of moist chilling to become germinable. Response to chilling was related to probable chilling duration at the collection site. Populations from habitats with severe winters produced seeds with long chilling requirements, while those from habitats with mild winters produced seeds with short chilling requirements. Populations from midelevation habitats produced seeds with intermediate chilling requirements but with a sizeable fraction whose dormancy was not broken by chilling of any length. Another pattern observed mostly in warm desert populations was little primary dormancy at autumn temperatures combined with induction of a fraction into secondary dormancy by short chilling. Species with a wide habitat range included populations with contrasting germination patterns. Parallel habitat-correlated patterns were observed in different sections. Most species showed germination patterns that combined predictive mechanisms with potential for carryover of a persistent seed bank. Results of common garden experiments suggested that germination differences had a strong genetic basis both among populations and among plants in a population. Adaptive radiation in the genus Penstemon has thus included the evolution of habitat-specific germination timing strategies in multiple lineages within the genus.     

Are there morphological and life‐history traits under climate‐dependent differential selection in S Tunesian Diplotaxis harra (Forssk.) Boiss. (Brassicaceae) populations?

Adaptation of morphological, physiological, or life‐history traits of a plant species to heterogeneous habitats through the process of natural selection is a paramount process in evolutionary biology. We have used a population genomic approach to disentangle selection‐based and demography‐based variation in morphological and life‐history traits in the crucifer Diplotaxis harra (Forssk.) Boiss. (Brassicaceae) encountered in populations along aridity gradients in S Tunisia. We have genotyped 182 individuals from 12 populations of the species ranging from coastal to semidesert habitats using amplified fragment length polymorphism (AFLP) fingerprinting and assessed a range of morphological and life‐history traits from their progeny cultivated under common‐garden conditions. Application of three different statistical approaches for searching AFLP loci under selection allowed us to characterize candidate loci, for which their association with the traits assessed was tested for statistical significance and correlation with climate data. As a key result of this study, we find that only the shape of cauline leaves seems to be under differential selection along the aridity gradient in S Tunisian populations of Diplotaxis harra, while for all other traits studied neutral biogeographical and/or random factors could not be excluded as explanation for the variation observed. The counter‐intuitive finding that plants from populations with more arid habitats produce broader leaves under optimal conditions of cultivation than those from more mesic habitats is interpreted as being ascribable to selection for a higher plasticity in this trait under more unpredictable semidesert conditions compared to the more predictable ones in coastal habitats.     

DISTRIBUTION OF DIURNAL ACID METABOLISM IN THE GENUS ISOETES

Previous studies have revealed a crassulacean acid metabolism-like pathway in the submerged aquatic Isoetes howellii (Isoetaceae). A survey of 11 other species in this largely aquatic genus showed all had diurnal fluctuations in titratable acidity and malic acid concentration. The magnitude of the diurnal fluctuation in titratable acidity varied from 119 (μeq g^–1 fresh weight) for I. bolanderi to 44 for I. engelmanni. Although these species were grown under similar conditions in a greenhouse, it is questionable whether or not any significance can be attached to observed species specific differences in magnitude of diurnal acid fluctuation. This is suggested by a single species comparison of plants in the field with greenhouse grown plants which indicated nearly as much variation in magnitude of acid fluctuations as observed across all species in the greenhouse. Much of this variation may be due to seasonal differences. Substrate appears to have very little effect on magnitude of acid fluctuations. Since this survey covered most of the range of the latitudinal, elevational, habitat, and morphological variation in the genus, it is likely that diurnal acid metabolism will prove to be common in the genus Isoetes.     

Microhabitat and morphometric variation of two Chaetophoracean (Chaetophorales, Chlorophyta) species in tropical streams of southeastern Brazil

Two populations of Chaetophora elegans (Roth) C. Agardh and two of Stigeoclonium helveticum Vischer were investigated for microhabitat characteristics and morphological variation in streams of São Paulo State, southeastern Brazil. Different patterns of microhabitat distribution were found between species investigated. Populations of C, elegans were distributed under relatively narrow microhabitat conditions (high irradiance, low depth, moderate to high current velocity, rocky substrata and lower values of niche width) and showing little morphometric variation (colony diameter, main axis cell size, and apical branch number), Stigeoclonium helveticum occurred under more diverse microhabitat conditions, revealed by lack of significant difference between sampling units with and without the alga and wider niche width, but also exhibited relatively narrow morphometric variation (plant length, main axis cell and ateral branch cell sizes). The narrow microhabitat conditions and smaller niche width of C. elegans can explain its low abundance (percentage cover) in streams from the area studied as well as in other regions of São Paulo State, In contrast, the wider variation of microhabitat conditions and the higher niche widths of S. helveticum suggest that this green alga is able to grow in a high number of stream ecosystems in the region investigated, ranging from undisturbed to highly disturbed habitats. Thus. the results suggest that S. helveticum is a generalist species.     

Morphological responses to nutrient availability in four clonal herbs

This paper examines morphological plasticity of clonal plants of contrasting habitats and of contrasting architectures in response to nutrient supply. The hypotheses were tested that plants from rich habitats possess greater plasticity in response to variation in resource supply than species from poor habitats, and that rhizomatous species are less plastic in their response than stoloniferous species. Two sympodial rhizomatous herbs (Carex flacca, C. hirta) and two monopodial stoloniferous herbs (Trifolium fragiferum, T. repens) were subjected to four levels of nutrient supply in a garden experiment. One of the two species of each genus (C. hirta, T. repens) is from fertile and the other from infertile habitats. We measured 1) whole plant characters: total plant dry weight, number of modules (product of a single apical meristem) and number of ramets; 2) ramet characters: ramet leaf area and ramet height; and 3) spacer characters: branches per module, length per module and length per module internode.All measured characters in the Trifolium species significantly responded to treatment: the values for all measured characters increased with higher levels of fertilization. The differences in plant characters between fertilization levels were larger in Trifolium repens than in T. fragiferum in terms of whole plant characters, ramet characters and stolon internode length. The two Carex species did not differ in their responses to treatment in terms of most characters measured. In ramet characters and in some whole plant characters the species from fertile habitats were more plastic than those from infertile habitats. In spacer characters this pattern was not found. Foraging could not be demonstrated unequivocally.Morphological plasticity in the stoloniferous (Trifolium) species was much larger than in the rhizomatous (Carex) species. This seems in accordance with a foremost storage function of rhizomes, as against a foremost explorative function of stolons.     

Phylogenetic study of benthic, spine-bearing prorocentroids, including Prorocentrum fukuyoi sp. nov.

Species of prorocentroid dinoflagellates are common in marine benthic sediment and epibenthic habitats, as well as in planktonic habitats. Marine planktonic prorocentroids typically possess a small spine in the apical region. In this study, we describe a new, potentially widely distributed benthic species of Prorocentrum, P. fukuyoi sp. nov., from tidal sand habitats in several sites in Australia and from central Japan. This species was found to possess an apical spine or flange and was sister species to P. emarginatum. We analyzed the phylogeny of the group including this new species, based on large subunit (LSU) rDNA sequences. The genus contained a high level of divergence in LSU rDNA, in some cases among sister taxa. P. fukuyoi and P. emarginatum were found to be most closely related to a clade of generally planktonic taxa. Several morphological features may constitute more informative synapomorphies than habitat in distinguishing clades of prorocentroid species.     

Zooplankton (Cladocera, Ostracoda), Chironomidae and other benthic faunal remains in sediment cores from nine North African wetland lakes: the CASSARINA Project

Palaeolimnological studies were carried out on sediment cores from nine North African wetland lakes. The lakes represented a variety of habitats ranging from freshwater to mixohaline conditions and with and without direct connections to the sea. Sediment cores were examined for records of recent environmental change during the 20th century period. Faunal remains analysed in the sediments included those of Cladocera, Ostracoda, Chironomidae, Mollusca and, at the sites with marine connections, Foraminifera. Cyprideis torosa littoralis was the most common ostracod, occurring in sediments from the seven sites linked with the sea and also in brackish water Sidi Bou Rhaba. In acid Megene Chitane ostracods were scarce, being represented by a single species (Cypria ophtalmica). Candona neglecta completely disappeared at two sites (Sidi Bou Rhaba and Bokka) during the 20th century. Of the Cladocera, Chydorus sphaericus was common in the moderately mixohaline sites and but Heterocypris salina occurred only where marine salinities were occasionally achieved (in Zerga, Ichkeul and Korba). Microinvertebrate assemblages in the Nile Delta lake cores and to a less extent in Zerga showed a clear response indicative of more fresher conditions occurring during the latter part of the 20th century. However the freshening trend began prior to construction of the Aswan High Dam (mid 1960s).With the exception of the most saline site (Korba), microinvertebrate communiuties at all the CASSARINA sites have experienced major disturbances during the 20th century. Changes in freshwater availability associated with increased human usage of water resources is perceived as a major factor regulating the abundance and occurrence of aquatic microinvertebrate species at these sites     

淫羊藿属植物形态分类性状评述

淫羊藿属是分类学上研究的热点和难点,其类群发表和修订均较频繁。为更清晰掌握淫羊藿属的性状变异,该文在查阅该属研究成果和标本的基础上,结合课题组野外调查和分析,对该属重要性状进行系统梳理。花瓣式样是淫羊藿属分类的最重要依据,但并非绝对稳定,种内花瓣形态可能存在丰富变异。花瓣颜色、花药颜色,甚至花的大小至少在部分类群中不宜作为分类的主要依据。根茎性状在多数类群中不失为一个有用的分类性状,但不能一概而论,应基于广泛调查。多数类群的花茎上叶的类型及小叶存在不同程度的变异,在实际应用中存在一定困难。非腺毛特征十分复杂,不同样本存在不同程度差异,不宜作为物种鉴别的关键依据。淫羊藿属植物栽培后植株普遍更矮小,提示开展自然生境下的调查和形态观测对掌握物种形态特征非常必要。中国淫羊藿属类群仍处于活跃进化中,其形态变异复杂,物种鉴定和资源利用时应足够谨慎。