Variabilidade morfológica e genética associadas aos morfotipos de cor de Callyspongia sp. nov. com comentários sobre a plasticidade fenotípica em Porifera

Abstract

Phenotypic plasticity is defined by the ability of organisms to respond in different ways to different environmental stimuli, changing their behavior, morphology or physiology. Changes in the morphology of sponges have been correlated with the action of the waves, the flow rate of currents and the sedimentation of the substrate, the variation in water temperature, the water movement, the availability of silica, and with biotics factors, such as predation and symbiosis. Phenotypic plasticity in sponges has been a source of difficulties for taxonomic analysis. In the first chapter, an extensive literature review of the concept of phenotypic plasticity in Porifera was carried out, and in the second chapter, the model of a species of Callyspongia Duchassaing & Michelotti, 1864 found on the Brazilian coast was used for a case study. In northeastern Brazil, several sponge color morphotypes of the sponge Callyspongia sp. nov. were observed: gray-green, blue / purple, yellow / orange and red, which may indicate the existence of cryptic species. In this study I describe morphological and molecular characters which contribute to determine the taxonomic status and test the hypothesis that Callyspongia sp. nov. on the Brazilian coast represents a complex of species, not a single polymorphic species. In total 55 samples Callyspongia sp. nov. collected in Salvador, were analyzed: 12 oranges, 15 blue / purple, 06 red and 22 gray / green, and other museum samples for comparison. The specimens of Callyspongia sp. nov., regardless of the morphotype, have an erect tubular shape, with surfaces full of conules, formed by spikes supported by espongin fibers, and a reticulation clearly visible to the naked eye. The coloring presents a great variety in vivo: gray, beige, green, cream, blue, purple, lilac, yellow, orange, red and pink. The skeleton is strongly stratified; the espongin fibers are filled by diactin spicules, the oxea type, and presents the espongin fibers integrated in a doble network, typical of the genus. The ectosome is formed by primary and secondary fibers, the primary fibers tend to have an irregular polygonal arrangement, since the secondary fibers tend to be among the primary fibers. The primary fibers are about 40 μm, and secondary fibers are about 30 μm. The endosome consists of elementary fibers 47-59,81-66 μm, secondary fibers 23-33,14-38 μm, and tertiary fibers 5-10,62-18 micrometers. The megascleres, of the oxea type, have sizes of 48-121 x 2 - 8 μm, and the microscleres, of the toxa type, from 8 to 19 micrometers. Three molecular markers were used: the mitochondrial 16S and cox1, and the internal transcribed spacers (ITS1 and ITS2) of the nuclear ribosomal RNA. After extraction of the total genomic DNA, each marker was amplified and sequenced in an automatic sequencer. The sequences were edited with the DNASTAR SeqMan® 7.1 program, aligned with the v6.935 MAFFT program, and the relationship between them, reconstructed using the MEGA6 program. Our results have shown that the color morphs are a single species.