Click
here to close Hello! We notice that
you are using Internet Explorer, which is not supported by Echinobase
and may cause the site to display incorrectly. We suggest using a
current version of Chrome,
FireFox,
or Safari.
PeerJ
2015 Jan 01;3:e1128. doi: 10.7717/peerj.1128.
Show Gene links
Show Anatomy links
Environmental influences on the Indo-Pacific octocoral Isis hippuris Linnaeus 1758 (Alcyonacea: Isididae): genetic fixation or phenotypic plasticity?
Rowley SJ
,
Pochon X
,
Watling L
.
Abstract
As conspicuous modular components of benthic marine habitats, gorgonian (sea fan) octocorals have perplexed taxonomists for centuries through their shear diversity, particularly throughout the Indo-Pacific. Phenotypic incongruence within and between seemingly unitary lineages across contrasting environments can provide the raw material to investigate processes of disruptive selection. Two distinct phenotypes of the Isidid Isis hippurisLinnaeus, 1758 partition between differing reef environments: long-branched bushy colonies on degraded reefs, and short-branched multi/planar colonies on healthy reefs within the Wakatobi Marine National Park (WMNP), Indonesia. Multivariate analyses reveal phenotypic traits between morphotypes were likely integrated primarily at the colony level with increased polyp density and consistently smaller sclerite dimensions at the degraded site. Sediment load and turbidity, hence light availability, primarily influenced phenotypic differences between the two sites. This distinct morphological dissimilarity between the two sites is a reliable indicator of reef health; selection primarily acting on colony morphology, porosity through branching structure, as well as sclerite diversity and size. ITS2 sequence and predicted RNA secondary structure further revealed intraspecific variation between I. hippuris morphotypes relative to such environments (ΦST = 0.7683, P < 0.001). This evidence suggests-but does not confirm-that I. hippuris morphotypes within the WMNP are two separate species; however, to what extent and taxonomic assignment requires further investigation across its full geographic distribution. Incongruence between colonies present in the WMNP with tenuously described Isis alternatives (Isis reticulataNutting, 1910, Isis minorbrachyblastaZou, Huang & Wang, 1991), questions the validity of such assignments. Furthermore, phylogenetic analyses confirm early taxonomic suggestion that the characteristic jointed axis of the Isididae is in fact a convergent trait. Thus the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members.
Figure 1. Isis hippuris morphotypes and location map of the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia.Isis hippuris morphotypes: (A) short branched predominantly planar or multiplanar colonies at the healthy site Ridge 1, and (B) long branched bushy colonies at the impacted site Sampela, with additional (C) collection localities within the WMNP. Sample number in brackets for molecular and asterisk for morphological analyses.
Figure 2. Isis hippuris morphological trait measurements plate.Isis hippuris morphological trait measurements of the (A) colony; (B, C, D) canal and polyp dynamics; (E) sub-colony (branching) dynamics; (F) sclerites site/morphotype comparisons of i and ii spindles, iii and iv capstan 7-radiates, v–vi and vii–viii clubs from Ridge 1 and Sampela respectively. All abbreviations are described in text.
Figure 3. Constrained ordinations (CAP) of Isis hippuris character traits.Constrained ordinations (CAP) of Isis hippuris character traits between Ridge 1 [◆] and Sampela [▴]. Vector abbreviations as described in text.
Figure 4. Isis haplotype network and ITS2 RNA predicted secondary structure.Isis haplotype network with corresponding ITS2 RNA predicted secondary structure relative to haplotype ((A–E), see also Fig. 5) and enthalpy values according to MFOLD. Roman numerals (I–IV) represent helices; red and black arrows indicate point mutations and loop differences, respectively. Coloured bases according to transitions (red), transversions (yellow) and gaps (lilac), S5. Haplotype circle diameters are proportional to identical clone sequences.
Figure 5. Phylogram of Isis haplotypes and Octocoral out groups.Phylogram based on Maximum Likelihood (ML) analyses of the ITS2 region from twenty Octocoral taxa in GenBank and Isis haplotypes within the WMNP. Branch numbers represent ML bootstrap support and BI posterior probabilities, respectively, with low values expressed as a hyphen (–) ≤70% and asterisk (*) indicative of differences from MrBayes phylogenetic inference. Letters Sc, Scleraxonia; Ca, Calcaxonia, Ho, Holaxonia, Al, Alcyoniina, and A–E represent Isis haplotypes as depicted in Fig. 4.
Armando Sánchez,
Phylogenetic analyses among octocorals (Cnidaria): mitochondrial and nuclear DNA sequences (lsu-rRNA, 16S and ssu-rRNA, 18S) support two convergent clades of branching gorgonians.
2003, Pubmed
Armando Sánchez,
Phylogenetic analyses among octocorals (Cnidaria): mitochondrial and nuclear DNA sequences (lsu-rRNA, 16S and ssu-rRNA, 18S) support two convergent clades of branching gorgonians.
2003,
Pubmed
Bergman,
Evolutionary capacitance as a general feature of complex gene networks.
2003,
Pubmed
Calosi,
What determines a species' geographical range? Thermal biology and latitudinal range size relationships in European diving beetles (Coleoptera: Dytiscidae).
2010,
Pubmed
Clavico,
Antipredator defense and phenotypic plasticity of sclerites from Renilla muelleri, a tropical sea pansy.
2007,
Pubmed
Coleman,
Secondary structure of the rRNA ITS2 region reveals key evolutionary patterns in acroporid corals.
2008,
Pubmed
Cossins,
Post-genomic approaches to understanding the mechanisms of environmentally induced phenotypic plasticity.
2006,
Pubmed
Darriba,
jModelTest 2: more models, new heuristics and parallel computing.
2012,
Pubmed
Darty,
VARNA: Interactive drawing and editing of the RNA secondary structure.
2009,
Pubmed
Excoffier,
Arlequin suite ver 3.5: a new series of programs to perform population genetics analyses under Linux and Windows.
2010,
Pubmed
Flatt,
The evolutionary genetics of canalization.
2005,
Pubmed
Guindon,
A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood.
2003,
Pubmed
Hoogenboom,
Interactions between morphological and physiological plasticity optimize energy acquisition in corals.
2008,
Pubmed
Huelsenbeck,
MRBAYES: Bayesian inference of phylogenetic trees.
2001,
Pubmed
Ladner,
Extensive sympatry, cryptic diversity and introgression throughout the geographic distribution of two coral species complexes.
2012,
Pubmed
Lasker,
Determinate growth and modularity in a gorgonian octocoral.
2003,
Pubmed
Librado,
DnaSP v5: a software for comprehensive analysis of DNA polymorphism data.
2009,
Pubmed
Magwene,
New tools for studying integration and modularity.
2001,
Pubmed
McFadden,
A molecular phylogenetic analysis of reproductive trait evolution in the soft coral genus Alcyonium.
2001,
Pubmed
Pigliucci,
Evolution of phenotypic plasticity: where are we going now?
2005,
Pubmed
Pochon,
A new Symbiodinium clade (Dinophyceae) from soritid foraminifera in Hawai'i.
2010,
Pubmed
Prada,
Phenotypic plasticity or speciation? A case from a clonal marine organism.
2008,
Pubmed
Prada,
Long prereproductive selection and divergence by depth in a Caribbean candelabrum coral.
2013,
Pubmed
Puritz,
Extraordinarily rapid life-history divergence between Cryptasterina sea star species.
2012,
Pubmed
,
Echinobase
Rice,
Theoretical approaches to the evolution of development and genetic architecture.
2008,
Pubmed
Schluter,
Ecology and the origin of species.
2001,
Pubmed
Seibel,
Synchronous visual analysis and editing of RNA sequence and secondary structure alignments using 4SALE.
2008,
Pubmed
Seibel,
4SALE--a tool for synchronous RNA sequence and secondary structure alignment and editing.
2006,
Pubmed
Shaish,
Branch to colony trajectory in a modular organism: pattern formation in the Indo-Pacific coral Stylophora pistillata.
2006,
Pubmed
Shearer,
Slow mitochondrial DNA sequence evolution in the Anthozoa (Cnidaria).
2002,
Pubmed
Simmons,
Gaps as characters in sequence-based phylogenetic analyses.
2000,
Pubmed
Simpson,
Species selection and the macroevolution of coral coloniality and photosymbiosis.
2013,
Pubmed
Sánchez,
Patterns of morphological integration in marine modular organisms: supra-module organization in branching octocoral colonies.
2003,
Pubmed
Sánchez,
Do multi-branched colonial organisms exceed normal growth after partial mortality?
2004,
Pubmed
Sánchez,
Phenotypic plasticity and morphological integration in a marine modular invertebrate.
2007,
Pubmed
Thompson,
Multiple sequence alignment using ClustalW and ClustalX.
2002,
Pubmed
Vollmer,
Hybridization and the evolution of reef coral diversity.
2002,
Pubmed
Wagner,
A POPULATION GENETIC THEORY OF CANALIZATION.
1997,
Pubmed
West,
Plasticity in the Sclerites of a Gorgonian Coral: Tests of Water Motion, Light Level, and Damage Cues.
1997,
Pubmed
Xu,
Differential influence of clonal integration on morphological and growth responses to light in two invasive herbs.
2012,
Pubmed
Young,
GapCoder automates the use of indel characters in phylogenetic analysis.
2003,
Pubmed
Zuker,
Mfold web server for nucleic acid folding and hybridization prediction.
2003,
Pubmed
