Morphological variation in the palaeonemertean Tubulanus annulatus (Montagu, 1804)

Previous studies on the palaeonemertean Tubulanus annulatus have hinted on possible geographic variation, or even a species complex. This study describes the variation in morphology, focusing on the characters that have been supposed to vary geographically. Specimens from the Swedish west coast (Tjärnö and Kristineberg), Scottish west coast (Millport), and the Mediterranean (Naples and Split) were included in the study. It is concluded that the pattern of variation in the studied characters do not correspond to geography and most of the character states previously thought to vary geographically are in fact found within one and the same population.     

Genetic connectivity of the scleractinian coral Goniastrea aspera around the Okinawa Islands

Genetic variation and gene flow in the scleractinian coral Goniastrea aspera (Verrill), found around the north–south Okinawa Islands, were studied using allozyme and starch gel electrophoresis. The relative contribution of sexual and asexual reproduction to recruitment was determined. Analysis of multilocus genotypes of samples, collected at least 3 m apart, identified a high number of unique genotypes (N_G) relative to the number of individuals sampled (N) (mean N_G: N=0.97±0.03 [SD]), and also highly observed genotypic diversity (G_O) relative to expected genotypic diversity under Hardy–Weinberg equilibrium (G_E) (mean G_O: G_E=0.95±0.06 [SD]). These results suggest that the collected G. aspera propagated predominantly by sexual reproduction in Okinawan populations. The UPGMA grouping of five populations in the Okinawa, based on Neis unbiased genetic distance, showed two clusters that were south and north Okinawa populations. AMOVA analyses that incorporated the data of populations from the Kerama and the Ishigaki Islands detected significant F_SC values among the populations within groups in analyses distinguishing north–south Okinawa, Okinawa–Kerama, and Okinawa–Kerama–Ishigaki. Significant F_CT values were neither detected between north–south Okinawa nor between the Okinawa–Kerama groups. The local-recruits hypothesis, which assumes that a substantial proportion of recruits is produced locally, appears to be applicable to coral populations in the Ryukyu Archipelago. On the other hand, detection of nonsignificant F_CT values indicated the presence of genetic connectivity between north–south Okinawa and Kerama–Okinawa groups.     

A poecilostome copepod parasitic in a scleractinian coral in the moluccas

Wedanus inconstans, n. gen., n. sp., a lichomolgid copepod living in the polyps of the reef coral Goniopora tenuidens (Quelch), is described from Halmahera in the Moluccas. The genus is apparently related to Xenomolgus Humes & Stock, 1972.     

Mitogenome rearrangement in the cold-water scleractinian coral Lophelia pertusa (Cnidaria, Anthozoa) involves a long-term evolving group I intron

Group I introns are genetic insertion elements that invade host genomes in a wide range of organisms. In metazoans, however, group I introns are extremely rare, so far only identified within mitogenomes of hexacorals and some sponges. We sequenced the complete mitogenome of the cold-water scleractinian coral Lophelia pertusa, the dominating deep sea reef-building coral species in the North Atlantic Ocean. The mitogenome (16,150 bp) has the same gene content but organized in a unique gene order compared to that of other known scleractinian corals. A complex group I intron (6460 bp) inserted in the ND5 gene (position 717) was found to host seven essential mitochondrial protein genes and one ribosomal RNA gene. Phylogenetic analysis supports a vertical inheritance pattern of the ND5-717 intron among hexacoral mitogenomes with no examples of intron loss. Structural assessments of the Lophelia intron revealed an unusual organization that lacks the universally conserved ωG at the 3′ end, as well as a highly compact RNA core structure with overlapping ribozyme and protein coding capacities. Based on phylogenetic and structural analyses we reconstructed the evolutionary history of ND5-717, from its ancestral protist origin, through intron loss in some early metazoan lineages, and into a compulsory feature with functional implications in hexacorals.     

Simulation and analysis of flow patterns around the scleractinian coral Madracis mirabilis (Duchassaing and Michelotti)

Three-dimensional morphologies of Madracis mirabilis were obtained using X-ray computed tomography scanning techniques. The morphologies were used to simulate the flow patterns around the colony. In the simulations, the thin-branching low-flow morph with a relatively larger branch-spacing was compared with the more compact high-flow morph of M. mirabilis. For both morphologies, the inside-colony flow velocities were computed for Reynolds numbers ranging from 154 to 3840. In the high-flow morph, it was found that in the range of investigated Reynolds numbers a stagnant region develops within the colony, whereas in the low-flow morph the stagnant region disappeared. Experiments done under natural conditions suggest that a morph is adapted to a certain external flow velocity and develops a stagnant region below a particular threshold for the external flow velocity. When the external flow velocity exceeds a certain threshold, which is characteristic for the growth form, the core velocity becomes equal to the external velocity. A potential application of a profile of core velocities for a range of Reynolds numbers for a certain morph is the prediction of the optimal external flow velocity for a certain morph, and this can be used to assess the state of the physical (palaeo-) environment.     

Host-associated speciation in the coral barnacle Wanella milleporae (Cirripedia: Pyrgomatidae) inhabiting the Millepora coral

Speciation by host shift is a common phenomenon observed in many symbiotic animals. The symbiont–host interaction is highly dynamic, but it is poorly documented in the marine realm. In the present study, we examined the genetic and morphological differentiation of the coral barnacle Wanella milleporae (obligate to fire corals) collected from four different Millepora host species in Taiwan to investigate the host specificity of this barnacle. Phylogenetic analysis of mitochondrial COI gene for 241 individuals of Wanella revealed five distinct clades, whose sequence divergences are comparable to values between other cogeneric barnacle species. The five clades also differ in shell and opercular plate morphology and colour. Genetic and morphological differentiations together strongly suggest the presence of cryptic species. Although the five clades do not display species-level host specificity, they showed a significant difference in preference on host growth form. Clades 1 and 2 were predominantly found on encrusting Millepora exaesa and Millepora platyphylla , while clades 3, 4 and 5 live exclusively on branching-form fire corals Millepora dichotoma and Millepora tenella . Phylogeny inferred from the combined mitochondrial COI, 16S and 12S (2182 bp) analysis suggests the division of the five clades into two major lineages congruent with the morphology of the host coral. Multiple independent invasions to the same form of host and subsequent speciation are evident in the Red Sea and Taiwan. Our results indicate that ecological/sympatric speciation could occur in marine symbiotic invertebrates through host shift and specialization. It appears that, as in their terrestrial counterparts, host–symbiont radiations in the marine realm are more prevalent than we expected and thus warrant further investigation.     

Comparative growth in the postnatal skull of the extant North American turtle Pseudemys texana (Testudinoidea: Emydidae)

Bever, G.S. 2007. Comparative growth in the postnatal skull of the extant North American turtle Pseudemys texana (Testudinoidea: Emydidae). —Acta Zoologica (Stockholm) 88 : 000–000 Postnatal growth is one of the many aspects of developmental morphology that remains distinctly understudied in reptiles. Variation and ontogenetic scaling within the skull of the extant emydid turtle, Pseudemys texana is described based on 25 continuous characters. Results indicate that skull shape in this species changes little during postnatal growth relative to the only cryptodire taxa for which comparable datasets are available (Apalone ferox and Sternotherus odoratus). This relative lack of change results in the paedomorphic retention of a largely juvenile appearance in the adult form of P. texana. The skulls of males and females, despite the presence of distinct sexual dimorphism in size, grow with similar scaling patterns, and the few observed differences appear to reflect alteration of the male growth trajectory. Comparisons with A. ferox and S. odoratus reveal a number of similarities and differences that are here interpreted within a phylogenetic context. These preliminary hypotheses constitute predictive statements that phylogenetically bracket the majority of extant cryptodire species and provide baseline comparative data that are necessary for the future recognition of apomorphic transformations. Plasticity of ontogenetic scaling as a response to the homeostatic needs and behaviour of individuals commonly is evoked as a limitation of ontogenetic scaling as a means to inform phylogenetic studies. These evocations are largely unfounded considering that variability itself can evolve and thus be phylogenetically informative.     

Morphological variation in Polydora ciliata complex (Polychaeta: Annelida)

Intraspecific variation in Polydora ciliata (Johnston) was assessed on the basis of evidence from morphological characters, which were studied by scanning electron microscopy. Differences were observed between populations of P. ciliata with respect to the setae of the fifth modified segment and in the caruncle. Two other species, namely P. ligni Webster and P. limicola (Annenkova), were also studied in order to assess interspecific variation. The two forms of P. ciliata , that is boring and non-boring, were found to be different morphologically.     

Patterns of morphological variation in the Acacia species (Mimosaceae) of northern Sudan

KORDOFANI, M. & INGROUILLE, M., 1991. Patterns of morphological variation in the Acacia species (Mimosaceae) of northern Sudan. A numerical taxonomic review has been carried out on the morphology of northern Sudanese Acacia species. Fifty-one characters were scored from 12 species sampled at 12 sites. There is evidence of large scale population variation. Within a single site species are distinct but a comparison of plants between different sites may obscure species differences. Each species has a peculiar local variant in each sampled site, even when sites are separated by only a few kilometres. The possible significance of this pattern of variation is discussed. Species complexes are delineated and useful species diagnostics described.     

Morphological variation of the saker (Falco cherrug) and the implications for conservation

The saker (Falco cherrug) is a traditional and valued bird of Arabic falconry. Harvesting birds from the wild raises questions of its conservation status and sustainability. The external morphology of this species is highly variable and the Arabic system of classification identifies over 11 saker types, some of which are more favoured among Arab falconers than others. Our study assessed morphological variation of birds chosen for known natal origin. Although most variation was between individuals-within-regions, the remaining variation in size and plumage characters may be appropriately described as a gradual cline between small dorsally uniform brown sakers from western lowland regions (e.g. lowland Kazakstan, and south-west Russia) to large, dorsally barred russet, dark brown and grey coloured sakers from eastern highland regions (e.g. south-east Russia, Mongolia, and China). Between these extremes exists a plethora of highly variable and contiguous populations. Although preferred falconry types may originate from any of these populations, the preferred jarudi and 'sinjari sakers from northeastern Altai, Tuva, and Sayan populations, and the large sakers from eastern populations may be over exploited through trapping. The demand for wild sakers, however, may be substituted by an increasing number of captive bred falcons used for Arab falconry.     

Morphological variation in the Serolis minuta-group (Isopoda: Serolidae) from Australian waters

Serolid isopods from soft sediments in three bays off Townsville (Queensland, Australia) are described. On the basis of existing keys they appear to fit into the Serolis minuta-group as S. minuta, S. bakeri and S. yongei. Although the first two species seem to be separated bathymetrically there is such a wide variation in the diagnostic characters that separation at the species level may no longer be tenable. Examination of serolids from other Australian localities confirms this view. Comparison of the taxonomy of the S. minuta-group is made with other Australian serolids, and with the American S. carinata-group. The need to examine a large number of specimens when attempting to understand problems of variation, and the importance of intensive surveys for supplying these specimens, is stressed.     

Genetic structure of Heliofungia actiniformis (Scleractinia: Fungiidae) populations in the Indo-Malay Archipelago: implications for live coral trade management efforts

The fungiid Heliofungia actiniformis is one of the most popular scleractinian coral species in the growing live aquarium trade, with the majority of specimens originating in Indonesia. Details on population connectivity may potentially provide important information with regards to harvest management efforts. Genetic structure was examined, using ribosomal ITS1, 5.8S and partial ITS2 sequences on a small scale among populations in the Spermonde Archipelago, South Sulawesi (up to 65 km distance, Φ_st = 0.09), and on a large scale throughout the Indo-Malay Archipelago (up to 2,900 km distance, Φ_st = 0.26). Significant genetic structuring was found at both scales. Within the Spermonde Archipelago isolation by distance as well as local oceanographic features shaped patterns of genetic connectivity. On the large scale, the data revealed genetically distinct populations in Tomini Bay, New Guinea and the Thousand Islands near Jakarta, and a lack of genetic differentiation among populations lying close to or directly in the path of the Indonesian throughflow: from the central Visayas to the Flores Sea (Φ_ct = 0.32). Whilst the influence of both historical and present day processes on genetic structuring of H. actiniformis populations was revealed, large scale results further emphasised the importance of oceanographic dynamics on larval dispersal patterns in this species. Potential for larval input from surrounding populations, and the increased vulnerability of upstream as well as isolated populations should be taken into consideration when setting future harvest quotas.     

Shaping intraspecific variation: Development,ecology and the evolution of morphology and life history variation in tiger salamanders

The tiger salamander,Ambystoma tigrinum, is a geographically widespread, morphologically variable, polytipic species. It is among the most variable species of salamanders in morphology and life history with two larval morphs (typical and cannibal) and three adult morphs (metamorphosed, typical branchiate, cannibal branchiate) that vary in frequency between subspecies and between populations within subspecies. We report morphometric evidence suggesting that branchiate cannibals arose through intraspecific change in the onset or timing of development resulting in the wider head and hypertrophied tooth-bearing skull bones characteristic of this phenotype. We also quantified bilateral symmetry of gill raker counts and abnormalities, then evaluated fluctuating asymmetry as a measure of the developmental stability of each morph. There was a significant interaction between fluctuating asymmetry of developmental abnormalities in cannibals and typicals and the locality where they were collected, suggesting that relative stability of each phenotype could vary among populations. While altered timing of developmental events appears to have a role in the evolution and maintenance of morphs, novel phenotypes persist only under favorable ecological conditions. Predictability of the aquatic habitat, genetic variation, kinship, body size, intraspecific competition and predation all affect expression and survival of the morphs inA. tigrinum. This taxon provides an excellent model for understanding the diversity and complexity of developmental and ecological variables controlling the evolution and maintenance of novel phenotypes.     

The geographic structure of morphological variation in eight species of fiddler crabs (Ocypodidae: genus Uca) from the eastern United States and Mexico

Species with larger geographic distributions are more likely to encounter a greater variety of environmental conditions and barriers to gene flow than geographically‐restricted species. Thus, even closely‐related species with similar life‐history strategies might vary in degree and geographic structure of variation if they differ in geographic range size. In the present study, we investigated this using samples collected across the geographic ranges of eight species of fiddler crabs (Crustacea: Uca) from the Atlantic and Gulf coasts of North America. Morphological variation in the carapace was assessed using geometric morphometric analysis of 945 specimens. Although the eight Uca species exhibit different degrees of intraspecific variation, widespread species do not necessarily exhibit more intraspecific or geographic variation in carapace morphology. Instead, species with more intraspecific variation show stronger morphological divergence among populations. This morphological divergence is partly a result of allometric growth coupled with differences in maximum body size among populations. On average, 10% of total within‐species variation is attributable to allometry. Possible drivers of the remaining morphological differences among populations include gene flow mediated by ocean currents and plastic responses to various environmental stimuli, with isolation‐by‐distance playing a less important role. The results obtained indicate that morphological divergence among populations can occur over shorter distances than expected based on dispersal potential. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 248–270.     

Complementary (secondary) metabolites in an octocoral competing with a scleractinian coral: effects of varying nutrient regimes

Competitive interactions between two sessile, epibenthic species were investigated on the Great Barrier Reef (GBR) in the presence and absence of added nutrients, as part of the Enrichment of Nutrients on Coral Reefs Experiment (ENCORE). Sarcophyton ehrenbergi Marenzeller (Octocorallia: Alcyonacea), an alcyonacean soft coral, and Pocillopora damicornis (Linnaeus), a scleractinian coral, were relocated and placed in contact with each other on large plastic grids on each of 12 micro-atolls within the One Tree Island (OTI) lagoon (23°30′S, 152°96′E, GBR). These micro-atolls were allocated in equal-sized groups to three enrichment treatments (addition of nitrogen, N; addition of phosphorus, P; addition of both nitrogen and phosphorus, N+P) and one control. Non-relocated (NR) and relocated colonies were also monitored as controls. After relocation and 1 year of nutrient enrichment, concentrations of a terpenoid complementary metabolite—sarcophytoxide—and wax esters were analyzed in colonies of S. ehrenbergi that had been exposed to elevated concentrations of N, P, N+P and compared with colonies on the non-nutrient-enriched control. Non-relocated control colonies from the natural environment were monitored over a period of 1 year and compared to colonies relocated to the control micro-atolls to assess handling effects. Analyses were performed on non-interacting S. ehrenbergi colonies, S. ehrenbergi colonies in experimental contact with P. damicornis colonies, and on non-interacting S. ehrenbergi colonies from the site of initial collection. Significant differences were found between sarcophytoxide levels in colonies of S. ehrenbergi in contact with P. damicornis vs. control/non-contact colonies; contact colonies had higher levels of this metabolite. Non-relocated control colonies of S. ehrenbergi exhibited significantly higher levels of sarcophytoxide than relocated control colonies. Augmentation of nutrient levels in micro-atolls significantly increased sarcophytoxide levels in S. ehrenbergi colonies relative to colonies on the control micro-atolls, although this response was not strong. Concentrations of fatty esters increased significantly through time in S. ehrenbergi colonies in their natural setting (non-relocated controls). This variability was not observed in relocated colonies in the treatment and control micro-atolls, irrespective of contact with P. damicornis. Concentrations of fatty esters in colonies of S. ehrenbergi in contact with P. damicornis were significantly lower than control/non-contact colonies, indicating that there is a cost in terms of stored energy reserves for the production of additional complementary metabolites when involved in competition for space. Augmentation of P levels in micro-atolls induced significant increases in fatty ester levels within S. ehrenbergi colonies vs. colonies in control micro-atolls, or in micro-atolls treated with added N or N+P together. These findings indicate that interspecific competition for space between a scleractinian coral and an alcyonacean soft coral and/or changes in the environmental nutrient regime can influence concentrations of complementary/secondary metabolites in the alcyonacean coral and the organism's stored energy reserves.