The meandering path to the discovering of cryptic sponge species
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1
Consejo Superior de Investigaciones Cientificas, Marinec Ecology, Spain
Introduction
Sponges are sessile, aquatic filter-feeders that represent the earliest branching metazoans in Earth, with a total of more than 8,000 accepted species and ca. 12,000 predicted to the end of the 21 century (Van Soest et al., 2012). Many of those potential species remain hidden within supposed widespread morph-species. Molecular markers are the tools of choice to reveal morphologically cryptic species (Blanquer & Uriz 2008; Uriz & Turon 2012). However, species that remain cryptic represent not only a drawback for sponge biodiversity assessment but to ecological and applied research projects as often they deeply differ in biological traits and thus interact in contrasting ways with other sharing habitat species.
Hemimycale columella (Demospongiae:Poecilosclerida) is a common sponge, widely distributed across the Northeastern Atlantic and Mediterranean basins (http://www.marinespecies.org/porifera). It has been recorded that some shallow populations disappeared yearly after reproduction (Pérez-Porro et al., 2012) while deep populations remain stable for years (authors’ obs.).
Searching for the potential causes of these contrasting behaviors, we analyzed growth dynamics and environmental factors of shallow and deep populations (Garate et al., this symposium) and search for genetic differences across the western, eastern, and central Mediterranean by using three gene partitions (nuclear and mitochondrial).
Methods
Species sampling across the Mediterranean was performed by SCUBA diving at six locations across the North, Central and East Mediterranean basins. COI, 18S and 28S gene partitions were amplified and sequenced in at least three randomly selected individuals per population. Phylogenetic trees were constructed under the Neighbor Joining (NJ), Bayesian Inference (BI) and Maximum likelihood (ML) clustering methods. Morphological traits of the sequenced individuals were carefully examined searching for phenotypic differences between species. Spicules were observed and measured through Scanning Electron Microscope. Contrasting life span and biological cycles (Garate et al., this symposium) were also considered.
Results
The resulting phylogenies with the three gene partitions consistently separated two monophyletic groups of individuals. Those from deeper Mediterranean populations clustered with the Atlantic H. columella sequence downloaded from the GenBank, while sequences from shallower populations across the Mediterranean were identical and formed a well-supported distinct clade.
The spicules (anisostronglyles, exclusively) were similar in shape and size across populations. Only slight differences in external color tinges, sponge thickness and height of the ring that surrounds inhaling areas could be discerned.
Moreover, the two monitored populations showed contrasting biological features (see Garate et al., this symposium). Survival curves diverged at both sites. A seasonal growth pattern was recorded only in the deep population, with higher growth rates in cold months. Mean growth rates were higher in the shallow population.
Conclusion
The up to now known as H. columella is a complex of at least two morphologically cryptic species: H.columella with an Atlanto-Mediterranean distribution, and H. mediterranea widespread across the western, central and eastern Mediterranean. Biological features differentiate both species more than morphological traits, as the Mediterranean clade has an annual life spam while H. columella is multiannual. Although reproduction almost overlapped growth showed contrasting patterns in populations of both species despite temperature and trophic conditions rather do not differ between their respective habitats (Garate et al., this symposium). Moreover both species harbor contrasting microbiomes (Garate et al., 2016).
Acknowledgements
This research has been partially funded by MARSYMBIOMICS, Spanish FECYT agency, grant ref. CTM2013-43286-P, and Benthic Ecology Consolidate Award (Generalitat of Catalonian, ref. 213-SGR-120) to MJU. Sampling was partially conducted in the frame of CoConet (EU, VII Frame Program, GA no 277844).
References
References
Van Soest RWM, Boury-Esnault N, Vacelet J, Dohrmann M, Erpenbeck D, De Voogd NJ, Santodomingo N, Vanhoorne B, Kelly M, Hooper JNA (2012) Global Diversity of Sponges (Porifera). PLoS ONE 7: e35105
Blanquer A, Uriz MJ (2008) ‘A posteriori ’ searching for phenotypic characters to describe new cryptic species of sponges revealed by molecular markers (Dictyonellidae : Scopalina) Invertebrate Systematics 22:489-502
Uriz MJ, Turon X (2012) Sponge ecology in the molecular era. Adv Mar Biol 61:345−410
Pérez-Porro AR, González J, Uriz MJ (2012) Reproductive traits explain contrasting ecological features in sponges: The sympatric poecilosclerid Hemimycale columella and Crella elegans as examples. Hydrobiologia 687:315–330
Garate L, Blanquer A, Uriz MJ (2016) Microbial communities across species and oceans (Submitted)
Keywords:
cryptic species,
Sponges,
Mediterranean,
Hemimycale columella,
Hemimycale mediterranea nv. sp.,
Atlantic
Conference:
XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016.
Presentation Type:
Oral Presentation
Topic:
1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS
Citation:
Uriz
MJ,
Garate
L and
Agell
G
(2016). The meandering path to the discovering of cryptic sponge species.
Front. Mar. Sci.
Conference Abstract:
XIX Iberian Symposium on Marine Biology Studies.
doi: 10.3389/conf.FMARS.2016.05.00009
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Received:
27 Apr 2016;
Published Online:
02 Sep 2016.
*
Correspondence:
Dr. Maria J Uriz, Consejo Superior de Investigaciones Cientificas, Marinec Ecology, Blanes, Girona, 173000, Spain, iosune@ceab.csic.es