Tetraclita ehsani sp. n. (Cirripedia, Tetraclitidae), a common intertidal barnacle from the Gulf of Oman, Iran

A new species of intertidal acorn barnacle Tetraclita ehsanisp. n. was identified from the Iranian coast in the Gulf of Oman. Tetraclita ehsanisp. n. inhabits low exposed rocky shores and also attaches to shells of molluscs and the barnacle Megabalanus species. Parietes of Tetraclita ehsani ranged from white to pink which is different from Tetraclita serrata (in South African waters), which has green parietes. Morphology of the tergum and cirrus III of Tetraclita ehsanisp. n. is distinctive from other described West Indian Ocean species which have pink or white parietes (Tetraclita rufotincta, Tetraclita achituvi and Tetraclita reni). The tergum of Tetraclita ehsani is very narrow and the basal margin is slightly concave or straight, in contrast to Tetraclita rufotincta and Tetraclita reni, in which the tergum are board and with a very concave basal margin. Cirrus I anterior ramus of both Tetraclita ehsani and Tetraclita reni is antenniform and thus differing from the cirrus I of Tetraclita rufotincta (see Chan et al. 2009). Cirrus III of Tetraclita ehsanisp. n. is non-antenniform and lacks multicuspidate type setae, which is different from Tetraclita reni by having an antenniform cirrus III and with multicuspidate setae.     

Effects of tidal height and wave exposure on cirrus and penis morphology of the acorn barnacle Tetraclita stalactifera

Exposure to wave action and other environmental factors can alter the morphology of intertidal barnacles. We tested several hypotheses on the causes of morphological variation in the cirri and penises of the barnacle Tetraclita stalactifera at sites differing in wave exposure, at different heights in the intertidal zone, and at different levels of population density. Unlike many other acorn barnacle species, cirrus and penis characteristics did not correspond to differences in wave exposure or crowding. However, barnacles from higher tidal elevations had thicker cirri and thicker penises than those from lower elevations. Because of reduced time submerged at higher elevations, increased thickness may be a means of compensating for reduced feeding and mating opportunity by allowing for continued feeding and mating attempts during periods of greater wave action. Our observations of differences in cirrus and penis morphology suggest that phenotypic plasticity in penis and cirrus characteristics are adaptations shared by the species T. stalactifera and other acorn barnacles, but that T. stalactifera responds differently to environmental stimuli than do other species.     

Description of a new species of Thais (Mollusca: Neogastropoda: Muricidae) from Taiwan, based on morphological and allozyme analyses

Thais keluo sp. nov. is described from intertidal shores of southwest Taiwan. The new species is differentiated from five other closely related species, namely T. bitubercularis (Lamarck), T. jubilaea Tan and Sigurdsson, T. clavigera (Küster), T. luteostoma (Holten) and T. rufotincta Tan and Sigurdsson, all of which occur in the South China Sea, on the basis of shell, radula and penis morphology. Thais keluo is also distinguished from the latter three species based on allozyme electrophoresis. The shell of T. keluo is characterized by four raised, spiral bands on the last whorl, one or two small, oblique columellar plica(e) on the inner lip, a finely crenate, thin, narrow, reddish-brown outer lip edge and four white, papillate denticles inside the outer lip of the aperture. In males, the penis is curved with a long, simple flagellum. The UPGMA cluster analysis based on 9 enzyme loci revealed that T. luteostoma is more closely related to T. clavigera than to T. keluo n.sp. The Nei's genetic distance (D) obtained between the new species and T. clavigera/T. luteostoma was 0.31, while T. clavigera and T. luteostoma were separated by a distance of 0.16. Thais rufotincta was separated from the other species by a distance of 0.78. In contrast, phylogenetic analysis of morphological data by maximum parsimony suggested that T. luteostoma was more closely related to T. keluo than to T. clavigera. However, both analyses indicated the close relationship amongst T. clavigera, T. luteostoma and the new species in relation to T. rufotincta.     

Phenotypic plasticity inPotamogeton (Potamogetonaceae)

Sources of the extensive morphological variation of the species and hybrids ofPotamogeton were studied, especially from the viewpoint of the stability of the morphological characters used inPotamogeton taxonomy. Transplant experiments, the cultivation of clones under different values of environmental factors, and the cultivation of different clones under uniform conditions were performed to assess the proportion of phenotypic plasticity in the total morphological variation. Samples from 184 populations of 41Potamogeton taxa were grown. The immense range of phenotypic plasticity, which is possible for a single clone, is documented in detail in 14 well-described examples. The differences among distinct populations of a single species observed in the field were mostly not maintained when grown together under the same environmental conditions. Clonal material cultivated under different values of environmental factors produced distinct phenotypes, and in a few cases a single genotype was able to demonstrate almost the entire range of morphological variation in an observed trait known for that species. Several characters by recent literature claimed to be suitable for distinguishing varieties or even species were proven to be dependent on environmental conditions and to be highly unreliable markers for the delimiation of taxa. The unsatisfactory taxonomy that results when such classification of phenotypes is adopted is illustrated by three examples from recent literature. Phenotypic plasticity was found to be the main source of morphological variation within the species ofPotamogeton, having much more influence than morphological differences caused by different genotypes.     

Distinct subspecies or phenotypic plasticity? Genetic and morphological differentiation of mountain honey bees in East Africa

Identifying the forces shaping intraspecific phenotypic and genotypic divergence are of key importance in evolutionary biology. Phenotypic divergence may result from local adaptation or, especially in species with strong gene flow, from pronounced phenotypic plasticity. Here, we examine morphological and genetic divergence among populations of the western honey bee Apis mellifera in the topographically heterogeneous East African region. The currently accepted “mountain refugia hypothesis” states that populations living in disjunct montane forests belong to a different lineage than those in savanna habitats surrounding these forests. We obtained microsatellite data, mitochondrial sequences, and morphometric data from worker honey bees collected from feral colonies in three montane forests and corresponding neighboring savanna regions in Kenya. Honey bee colonies from montane forests showed distinct worker morphology compared with colonies in savanna areas. Mitochondrial sequence data did not support the existence of the two currently accepted subspecies. Furthermore, analyses of the microsatellite data with a Bayesian clustering method did not support the existence of two source populations as it would be expected under the mountain refugia scenario. Our findings suggest that phenotypic plasticity rather than distinct ancestry is the leading cause behind the phenotypic divergence observed between montane forest and savanna honey bees. Our study thus corroborates the idea that high gene flow may select for increased plasticity.     

Geometric morphometrics, neural networks and diagnosis of sibling Taterillus species (Rodentia, Gerbillinae)

The lack of diagnostic traits in sibling species means that great quantities of biogeographical and ecological data held in museum collections cannot be utilized effectively, leading to underestimates of biodiversity. In this study we applied neural networks (NN) and canonical variates analyses (CVA) to landmark measurements on the skulls of the West African species Taterillus arenarius , T. petteri , T. gracilis and T. pygargus in an attempt to discriminate species previously identified unambiguously from their karyotypes. Among suggested differences, the relationship between inflation of the tympanic bullae and lower population density is discussed. Cross-validated classification rates did not exceed 73%. Two hypotheses are proposed to explain such high phenotypic similarity: morphological plasticity limited by environmental constraints and the possibility that speciation has been too recent to allow significant morphological divergence.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 319−327.     

Phenotypic plasticity and genetic isolation-by-distance in the freshwater mussel <Emphasis Type="Italic">Unio pictorum</Emphasis> (Mollusca: Unionoida)

Freshwater mussels (Unionoida) show high intraspecific morphological variability, and some shell morphological traits are believed to be associated with habitat conditions. It is not known whether and which of these ecophenotypic differences reflect underlying genetic differentiation or are the result of phenotypic plasticity. Using 103 amplified fragment length polymorphism (AFLP) markers, we studied population genetics of three paired Unio pictorum populations sampled from two different habitat types (marina and river) along the River Thames. We found genetic differences along the Thames which were consistent with a pattern of isolation by distance and probably reflect limited dispersal via host fish species upon which unionoid larvae are obligate parasites. No consistent genetic differences were found between the two different habitat types suggesting that morphological differences in the degree of shell elongation and the shape of dorso-posterior margin are caused by phenotypic plasticity. Our study provides the first good evidence for phenotypic plasticity of shell shape in a European unionoid and illustrates the need to include genetic data in order properly to interpret geographic patterns of morphological variation.     

The structural, compositional and mechanical features of the calcite shell of the barnacle Tetraclita rufotincta

The microstructure and chemical composition of the calcite shell of the sea barnacle Tetraclita rufotincta (Pilsbry, 1916) were investigated using microscopic and analytical methods. The barnacle shell was separated mechanically into its three substructural units: outer, interior, and inner layers. The organic matrices of these structural parts were further separated into soluble and insoluble constituents and their characteristic functional groups were studied by FTIR. Investigation of the mechanical properties of the interior mass of the shell reveals remarkable viscoelastic behavior. In general, the mechanical behavior of the shell is a function of its geometry as well as of the material, of which it is constructed. In the case of T. rufotincta, as calcite is a brittle material, the elastic behavior of the shell is apparently related to its micro- and macroarchitecture. The latter enables the shell to fulfill its primary function which is to protect the organism from a hostile environment and enables its survival. Our detailed identification of the similarities and differences between the various structural components of the shell in regard to the composition and properties of the organic component will hopefully throw light on the role of organic matrices in biomineralization processes.     

Leaf morphological plasticity in three dominant tree species in the Sundarbans mangrove forest of Bangladesh in different salinity zones

Mangrove tree species show plasticity in their leaf morphological traits in different salinity zones. However, leaf morphological plasticity and its causes in different salinity zones are incompletely understood. To understand the mechanism of plasticity, this study investigated the responses of three dominant tree species Sundri (Heritiera fomes), Gewa (Excoecaria agallocha) and Goran (Ceriops decandra) of the Sundarbans to the salinity gradients. A total of 17 leaf parameters were measured and quantified. All collected data were analyzed using univariate and multivariate statistical tools to investigate leaf morphological plasticity. A wide range of phenotypic plasticity was observed in all leaf parameters studied among the salinity zones of the Sundarbans. One-way ANOVA and Tukey’s posthoc test revealed significant differences (P?<?0.05) in all leaf parameters among the salinity zones and confirming that there was a high degree of phenotypic plasticity among the salinity zones of the Sundarbans. Petiole length (PL), leaf area (LA) and leaf length/petiole length (LL/PL) showed high level of plasticity among the salinity zones of the Sundarbans for each species of Sundri, Gewa and Goran. Plasticity index (PI) was developed in this study for each species studied. High level of phenotypic plasticity in these leaf traits reflects fitness of these species to different saline environments. Our results provide clear evidence that all the leaf parameters measured for three tree species viz., Sundri, Gewa and Goran effectively utilizes a plastic strategy in different salinity zones in the Sundarbans. Morphological trait plasticity could serve as powerful biological indicators to predict the shift of leaf morphology in upcoming environmental change events like sea level rise and reduction of fresh water flow from upstream.

     

Which Extent is Plasticity to Light Involved in the Ecotypic Differentiation of a Tree Species from Savanna and Forest?

Light intensity and heterogeneity are some of the main environmental factors that differ between forest and savanna habitats, and plant species from these habitats form distinct functional types. In this study, we tested the hypothesis that not only differences in morphological and physiological traits but also phenotypic plasticity in response to light are involved in adaptation to forest and savanna habitats by investigating ecotypic differentiation between populations of Plathymenia reticulata (Leguminosae: Mimosoideae), a tree from the Brazilian Atlantic Forest and the Brazilian Cerrado (savanna). Seeds from four natural populations (one from each biome core area and two from ecotonal regions) were grown in a common garden with four light treatments. Fifteen morphological and physiological characteristics were evaluated until individuals reached 6 mo old. Comparisons among populations showed differences for seven traits in at least one light treatment. These differences pointed to local adaptation to different biomes. Populations showed different levels of phenotypic plasticity in response to light in seven traits. Higher plasticity was found either in the forest core population or ecotonal populations; lower values were found in the cerrado core population. Lower plasticity in the cerrado population emphasizes the stress resistant syndrome, as lower plasticity is probably advantageous in a habitat where a conservative resource use is crucial. Higher plasticity in forest individuals suggests higher ability in exploiting the light heterogeneity in this habitat. Also, higher plasticity in ecotonal populations can be important to ensure the maintenance of P. reticulata in these temporally and spatially dynamic areas. Abstract in Portugese is available at http://www.blackwell‐synergy.com/loi/btp .     

Phenotypic plasticity closely linked to climate at origin and resulting in increased mortality under warming and frost stress in a common grass

Phenotypic plasticity is important for species responses to global change and species coexistence. Phenotypic plasticity differs among species and traits and changes across environments. Here, we investigated phenotypic plasticity of the widespread grass Arrhenatherum elatius in response to winter warming and frost stress by comparing phenotypic plasticity of 11 geographically and environmentally distinct populations of this species to phenotypic plasticity of populations of different species originating from a single environment. The variation in phenotypic plasticity was similar for populations of a single species from different locations compared to populations of functionally and taxonomically diverse species from one environment for the studied traits (leaf biomass production and root integrity after frost) across three indices of phenotypic plasticity (RDPI, PIN, slope of reaction norm). Phenotypic plasticity was not associated with neutral genetic diversity but closely linked to the climate of the populations’ origin. Populations originating from warmer and more variable climates showed higher phenotypic plasticity. This indicates that phenotypic plasticity can itself be considered as a trait subject to local adaptation to climate. Finally, our data emphasize that high phenotypic plasticity is not per se positive for adaptation to climate change, as differences in stress responses are resulting in high phenotypic plasticity as expressed by common plasticity indices, which is likely to be related to increased mortality under stress in more plastic populations.     

Exploring phenotypic plasticity and biogeography in emerald moths: A phylogeny of the genus Nemoria (Lepidoptera: Geometridae)

The moth genus Nemoria (Lepidoptera: Geometridae) includes 134 described species whose larvae and adults display a considerable range of phenotypic plasticity in coloration and morphology. We reconstructed the phylogeny of 54 species of Nemoria and seven outgroups using characters from the mitochondrial genes, Cytochrome Oxidase I and II (COI and COII), and the nuclear gene, Elongation Factor-alpha (EF-1alpha). Maximum parsimony, maximum likelihood and Bayesian inference were used to infer the phylogeny. The 54 ingroup species represented 13 of the 15 recognized species groups of Nemoria [Ferguson, D.C., 1985. Fasc. 18.1, Geometroidea: Geometridae (in part). In: Dominick, R.B. (Ed.), The Moths of America North of Mexico, Fasc. 18.1. Wedge Entomological Research Foundation, Washington; Pitkin, L.M., 1993. Neotropical emerald moths of the genera Nemoria, Lissochlora and Chavarriella, with particular reference to the species of Costa Rica (Lepidoptera: Geometridae, Geometrinae). Bull. Br. Mus. Nat. Hist. 62, 39-159], and the seven outgroups came from four tribes of Geometrinae. These data support Nemoria as a monophyletic group and largely recover the species groupings proposed in previous taxonomic analyses using morphological characters. Phenotypic plasticity of larvae is not correlated with plasticity of adults among those species of Nemoria where life histories are known, and appears to be evolutionarily labile for both life history stages: Species exhibiting larval phenotypic plasticity, such as N. arizonaria and N. outina, are placed in several distinct clades, suggesting that this trait has evolved multiple times, and species displaying adult phenotypic plasticity are likewise distributed throughout the phylogeny. A comparative analysis of the biogeographic history of Nemoria supports a South American origin for the genus with multiple introductions into North America, and an application of published substitution rates to the phylogram provides an age estimate of 7.5 million years.     

Phenotypic Plasticity in the Annual Weed Polygonum aviculare

Reaction norms of fourteen life history and morphological traits were investigated in four tetra- and two hexaploid genotypes of the annual weed species complex, Polygonum aviculare. The plants were cultivated in six treatments consisting of factorial combinations of three pot sizes and two fertility levels. All characters, except life span, were plastic but the relative importance of genotype (G), treatment (T) and interaction (G × T) to total variance was strongly trait-specific. Consistent genetic differentiation, not correlated with ploidy level, was found in metamer size and life history: genotypes originating from trampled sites had smaller metamers and shorter shoots while those originating from sites with a short growing season, due to weeding activities, had a shorter life span, an earlier flowering date and a higher biomass allocation to reproduction compared to genotypes from less disturbed sites. Significant variation was found in reaction norms for all characters, including a lower amount of plasticity in metamer size in genotypes with numerous metamers and a lower amount of plasticity in total weight in shortlived genotypes. This suggested that variation in phenotypic plasticity reflected developmental constraints imposed by contrasting life span and metamer size in different genotypes. There was no evidence for niche differentiation along the soil resource gradient, suggesting that the species is comprised of “general purpose” genotypes with respect to soil fertility. It is concluded that the Polygonum aviculare complex has evolved a “dual” adaptive strategy i.e. a combination of genetic polymorphism and high phenotypic plasticity.     

Streptacidiphilus jiangxiensis sp. nov., a novel actinomycete isolated from acidic rhizosphere soil in China

The taxonomic position of three acidophilic actinomycetes isolated from acidic rhizosphere soil was established using a polyphasic approach. The morphological and chemical properties of the isolates were found to be consistent with their assignment to the genus Streptacidiphilus. Almost complete 16S rRNA gene sequences determined for the strains were aligned with corresponding sequences of representatives of the genera Kitasatospora, Streptacidiphilus and Streptomyces and phylogenetic trees inferred using three tree-making algorithms. The organisms formed a distinct subclade within the Streptacidiphilus 16S rRNA gene tree. They also shared nearly identical phenotypic profiles and rep-PCR fingerprint patterns that readily distinguished them from representatives of the established species of Streptacidiphilus. It is evident from the genotypic and phenotypic data that the three isolates form a new species in the genus Streptacidiphilus. The name proposed for this new species is Streptacidiphilus jiangxiensis, the type strain is isolate 33214T (= AS 4.1857T = JCM 12277T).     

Morphological and genetic differentiation of the acorn barnacle Tetraclita squamosa (Crustacea, Cirripedia) in East Asia and description of a new species of Tetraclita

The common intertidal barnacle Tetraclita squamosa occurs in two morphologically and genetically distinct forms in East Asia. The north-western Pacific form (Japan, Okinawa and Taiwan) has green parietes and the tergo-scutal flaps are black without any patterns. The south China form (Xiamen, Hong Kong) also has green parietes but the tergo-scutal flaps are black with two white spots on the tergal and scutal margin. Compared to the NW Pacific form, the south China form has a beaked tergum, a sharper tergal spur and cirrus I lacks serrulate type setae that have four rows of setules. The two forms differ by 15–16% in COI divergence, which is comparable to values for other congeneric barnacle species. The 12S rRNA and ITS1 sequences are also distinct between the two forms. Our results support the conclusion that the two forms are genetically differentiated species. We describe the NW Pacific form as a new species, Tetraclita pacifica . We are treating the other species as Tetraclita squamosa based on the fact that Pilsbry, in 1916, redescribed T. squamosa squamosa using samples collected from south China and the Philippines. Further studies are needed to confirm the identity and geographical distribution of the 'widely distributed' T. squamosa in the Indo-West Pacific.     

Plasticity and genotypic variation in some Mentha × verticillata hybrids

Leaf and flower oil terpene composition and several plant morphological characteristics of 17 Mentha × verticillata hybrids were analysed during two growing seasons (1988 and 1989). The data obtained were used to study the phenotypic plasticity, the genotypic variation and the genetic variation for phenotypic plasticity. All plants showed high leveis of phenotypic plasticity for both oil chemical and morphometrical parameters. Higher degrees of genotypic variation were found among the plants for oll components while a higher phenotypic plasticity was observed for morphological parameters. Temperatures and rainfall data were collected during the growing seasons and correlated to the data obtained from plant oil and morphology. Low levels of phenotypic plasticity and high degrees of genotypic variation were found to form outliers in the population of M. x verticillata hybrids. The results obtained confirm a significant effect of environmental conditions on the physiology and morphology of the genus Mentha.     

Trophic polymorphism in introduced pumpkinseed (<Emphasis Type="Italic">Lepomis gibbosus</Emphasis>) inhabiting Iberian reservoirs

Introduced pumpkinseed in Iberian reservoirs display marked external morphological differentiation along two simultaneous dimensions of flow and trophic structure. We assessed the degree of internal morphological differentiation using gill rakers, pharyngeal jaws and the levator posterior muscle among pumpkinseeds occupying four different habitats and determined whether prey consumption accounted for any discernible differences in feeding structures among ecomorphs. Results showed significant differentiation by habitat based on pharyngeal muscle and jaw dimensions in all study reservoirs, with pelagic pumpkinseeds having smaller jaws than littoral pumpkinseeds in four of the five reservoirs. Gill rakers, however, differentiated morphs in only three of the five reservoirs, corresponding to differences in zooplankton consumption among pelagic and littoral individuals in those reservoirs. Based on all internal morphological traits, greater divergence was seen along the littoral-pelagic trophic axis in the lacustrine zones of reservoirs compared to the fluvial zone. Overall differences noted in internal morphology are likely the result of phenotypic plasticity; the ability of this species to readily adapt to changing physical environments may explain the success of the pumpkinseed in its introduced range.     

Insulin signalling underlies both plasticity and divergence of a reproductive trait in Drosophila

Phenotypic plasticity is the ability of a single genotype to yield distinct phenotypes in different environments. The molecular mechanisms linking phenotypic plasticity to the evolution of heritable diversification, however, are largely unknown. Here, we show that insulin/insulin-like growth factor signalling (IIS) underlies both phenotypic plasticity and evolutionary diversification of ovariole number, a quantitative reproductive trait, in Drosophila. IIS activity levels and sensitivity have diverged between species, leading to both species-specific ovariole number and species-specific nutritional plasticity in ovariole number. Plastic range of ovariole number correlates with ecological niche, suggesting that the degree of nutritional plasticity may be an adaptive trait. This demonstrates that a plastic response conserved across animals can underlie the evolution of morphological diversity, underscoring the potential pervasiveness of plasticity as an evolutionary mechanism.     

Phenotypic plasticity in alpine Erigeron species (Asteraceae)

Utelli, A.-B., Huber, W. & Zopfi, H.-J. 1995. Phenotypic plasticity in alpine Erigeron species (Asteraceae). — Nord. J. Bot. 15: 483–492. Copenhagen. ISSN 0107–055X.
Twelve morphological characters were analysed in 67 E. alpinus, E. neglectus and E. uniflorus plants which had been transplanted from their natural habitat to the greenhouse. Mean values and standard deviations were compared for each species. The phenotypic plasticity of the characters resp. their genetic basis was estimated from the correlation of morphological data recorded on single individuals, each grown under both ecological conditions.
A considerable phenotypic plasticity was found in all species and for most characters. E. unijlorus was the most constant species regarding taxonomically relevant characters such as pubescence of the basal leaves, number of flowering heads and number of filiform flowers. In all three species the same highly significant directional variation in plant height and involucre length was found which suggests that these characters have some genetic basis in Erigeron .     

Biosystematic Studies on Adenophora potaninii Korsh. Complex (Campanulaceae). Ⅰ. Phenotypic Plasticity

Phenotypic plasticity is the environmental modification of genotypic expression and an important means by which individual plants respond to environmental heterogeneity. The study of phenotypic plasticity in the genus Adenophora, which is very complicated taxo nomically because of great morphological variation, proves to be helpful in both investigating the phenotypic variation so as to evaluate potential taxonomic value of their characters and providing important sources of information on the variation, adaptation and evolution of the genus. Twenty-three populations representing all the six species in Adenophora potaninii complex were transplanted into the garden. Of them six populations were selected for study ing their performance in the field and in the garden, in addition to cultivation experiment under different treatments. The results show that there exists considerable developmental plasticity in some leaf, floral and capsule characters. In particular, the leaf shape and length of calyx lobe display significant developmental variation with the maximum being three times as great as the minimum, which is noteworthy because they were previously considered as diagnostic. The characters of root, caudex, stem and inflorescence are found to be very plastic, especially the root diameter, the number of stems, stem height and inflorescence length with great environmental plasticity. In addition, the populations from different habi tats show distinct amounts of plasticity. On the contrary, the characters of leaf, floral, cap sule and seed are less influenced by environments. It seems that the considerable variation in the characters of leaf is attributed mainly to genetic differences. Finally, the phenotypic plasticity of morphological characters of A. potaninii complex and its taxonomic significanceis discussed.