Genetic and morphological diversity of the sea cucumber morphospecies Holothuria tubulosa Gmelin, 1791 in the northern and central Adriatic Sea

Sertić, Maya (2016) Genetic and morphological diversity of the sea cucumber morphospecies Holothuria tubulosa Gmelin, 1791 in the northern and central Adriatic Sea. Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

Sea cucumber species are difficult to distinguish, and the status of several taxa in the Mediterranean Sea has been a source of dispute for over a century. This is the first study using genetic analysis to differentiate holothuroid species in the Adriatic Sea. Genetic barcoding of the COI mitochondrial gene was used to analyze the genetic diversity of the H. tubulosa Gmelin, 1791 morphospecies in the northern and central Adriatic, and genetic patterns were compared with the morphological traits historically used to distinguish H. tubulosa from the closely related H. mammata Grube, 1840 and H. stellati Delle Chiaje, 1824. In addition, a specimen previously identified as H. sp. cf. mammata based on its morphological characteristics was analyzed. While genetic analyses showed that the H. sp. cf. mammata specimen is actually H. tubulosa, 12 of the 37 collected specimens were genetically identified as H. mammata, suggesting that the morphological traits traditionally used in species identification may not be dependable for distinguishing these two species. A model using external morphological characteristics distinguished the two species with 91.9% accuracy, and a similar model using ossicle characteristics distinguished the species with 100% accuracy. None of the genetically identified taxa associated with the H. stellati morphotype, suggesting that this morphotype belongs to the H. tubulosa species. Overall, this study shows high potential for distinguishing H. tubulosa and H. mammata based on external morphology, and calls into question the historically accepted sea cucumber assemblage in the Adriatic Sea, which regarded H. mammata as a rare species and generally disregarded its presence in large census studies.

Item Type: Thesis (Diploma thesis)
Keywords: Echinodermata, Holothuria tubulosa, Holothuria mammata, Adriatic Sea, Mediterranean Sea, genetic barcoding, mtDNA
Supervisor: Hamer, Bojan and Kružić, Petar
Date: 2016
Number of Pages: 60
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Grozdana Sirotic
Date Deposited: 17 Jan 2017 10:03
Last Modified: 17 Jan 2017 10:03
URI: http://digre.pmf.unizg.hr/id/eprint/5417

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