A marine systematic conservation plan for Rodrigues Island, Western Indian Ocean

Includes abstract.Includes bibliographical references (p. 53-59).In 2007 the local government of Rodrigues gazetted four marine reserves in the north of the island based on knowledge and insights from stakeholders, mainly from the fishing community. In order to verify the stakeholder-based design, a marine reserve network was designed using Marxan, a systematic conservation planning programme

A genetic approach to the conservation of marine sponges in the Western Indian Ocean, with emphasis on the Mascarene Archipelago

Thesis (PhD)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Marine sponges are an important component of benthic ecosystems globally. They have evolved to adapt to very different environments, thus resulting in a global distribution. However the vast diversity of sponges is still largely unknown and undescribed. Sponges lack complex morphological characteristics, and this makes it difficult to describe their taxonomic diversity. Skeletal and spicule analysis allows for morphological identification, but these characteristics have certain limitations. With new molecular techniques, the field of sponge taxonomy has recently accelerated, with studies unravelling the classification of sponges with different lineages of same species observed across various geographic regions. This highlights that sponge diversity is vastly underestimated using traditional morphological methods. Consequently, recent studies are using an integrated approach combining morphological taxonomy with molecular techniques to obtain more information on the taxonomic and systematic classification of sponges. The Mascarene Islands comprise of a group of three islands (Rodrigues, Mauritius and Reunion) which emerged from the ocean at different time periods over the past eight million years. Due to its isolation in the middle of the Western Indian Ocean, the Mascarene Islands provide a natural laboratory for phylogenetic and phylogeographic studies. Sponges are considered as the oldest living metazoans and at a regional scale, no studies have been undertaken on sponges in the Mascarenes. This PhD therefore assessed the biodiversity of sponges collected from the shallow waters of all three Mascarene Islands using both morphological and molecular approaches. The samples were identified based on morphological characteristics (spicule and skeletal). With morphological methods, the highest sponge diversity was observed in Mauritius, followed by Reunion and Rodrigues. Two main factors may explain the lowest sponge diversity in Rodrigues, firstly the small size of the island compared to the other two, and secondly its more recent emergence from the ocean. In order to validate the results obtained from the morphological taxonomy, molecular tools were then utilised to assess the biodiversity of the Mascarene sponges. The phylogenetic relationships were established and compared with similar georeferenced species available on GenBank using both mitochondrial CO1 and nuclear 28S markers. The results generally validated the morphological classification, but cryptic lineages were observed for several species thus confirming that the morphological taxonomy underestimated the true sponge biodiversity present. The global phylogenetic analyses revealed that the Mascarene sponges were largely isolated from other species found outside the Mascarene region. A regional phylogenetic reconstruction was undertaken using concatenated CO1 and 28S sequences obtained from the Mascarene sponges, with main findings showing that the sponges found in Mauritius are phylogenetically closest to those from Reunion. Lastly, a phylogeographic study was carried out for the lemon sponge, Leucetta chagosensis, which is a widely distributed sponge species in the Indo-Pacific region. Six major lineages were observed in the phylogenetic tree produced, which reinforced the hypothesis that sponges tend to adapt in their respective geographical locations with physical barriers shaping their evolution. Overall, the sponge biodiversity in the Mascarene region was described using both morphological and molecular methods and their phylogenetic relationships were assessed in the context of global sponges. This study provides an important baseline for understanding sponge biodiversity and evolution in the Mascarene Islands, as well as highlight potential conservation implications. Furthermore, the use of both morphological taxonomy coupled with molecular phylogenies have been shown to be crucial for better understanding the relationship between sponges as well as assessing their diversity.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Doctora

Molecular studies on the Creole cattle breed in Mauritius

ABSTRACT There are three main cattle breeds in Mauritius; the Friesian cows, the Creole cows and the Cross (Creole and Friesians) breeds. The main objective of the study was to differentiate the Creole breeds from the other two breeds thus valorizing and conserving the Creole cow which is in danger of extinction. Random Amplified Polymorphic DNA and random microsatellite analysis were the two PCR based techniques used. The populations studied consisted of 5 Friesians, 5 Creole breeds and 5 Cross breeds. The breeds were obtained from the Curepipe Livestock Research Station which is the only place where there is a record of Creole cows in Mauritius. Among the 5 Creoles breeds chosen, 2 of them could have been impure breeds due to their morphological characteristics. DNA extraction was carried out from blood taken from the cows selected, and yielded DNA of good quality and quantity. Polymorphic bands were obtained from the Random Amplified Polymorphic DNA primers and random microsatellite primers and the data obtained were used for constructing a dendogram. From the dendogram obtained, the breeds were separated and the two Creole samples, which were suspected to be impure, formed different clusters from the true Creole breeds. From the results obtained, the Creole breed was easily distinguishable from the other breeds studied using molecular techniques

Indo-Pacific Phylogeography of the Lemon Sponge Leucetta chagosensis

The sponge Leucetta chagosensis Dendy (1913) has a wide distribution throughout the Indo-Pacific (IP) region, with previous studies focussing primarily on the western Pacific Ocean. To increase our knowledge of the spatial variation of genetic diversity throughout the IP, we constructed a phylogeny for L. chagosensis for the IP to assess the evolutionary patterns for this species. We generated 188 sequences of L. chagosensis and constructed maximum likelihood and Bayesian inference trees, using concatenated mitochondrial cytochrome oxidase subunit 3 gene (cox3) and nuclear ribosomal RNA gene (28S) markers for the first time. The spatial variation of genetic diversity of L. chagosensis was assessed using a phylogeographic approach. Leucetta chagosensis is composed of five cryptic lineages confined to different biogeographic regions with the specimens found in the Indian Ocean differing significantly from those found in the rest of the IP region. Genetic divergence was particularly high for the cox3 marker, with a low nucleotide diversity but high haplotype diversity for most lineages. This study highlights the need for a sustained effort in studying sponge diversity, boosted by the ongoing discovery of hidden biodiversity among this ecologically important taxon

Indo-Pacific phylogeography of the lemon sponge Leucetta chagosensis

CITATION: Pasnin, O. et al. 2020. Indo-Pacific phylogeography of the lemon sponge Leucetta chagosensis. Diversity, 12(12):466, doi:10.3390/d12120466.The original publication is available at https://www.mdpi.comThe sponge Leucetta chagosensisDendy (1913) has a wide distribution throughout the Indo-Pacific (IP) region, with previous studies focussing primarily on the western Pacific Ocean. To increase our knowledge of the spatial variation of genetic diversity throughout the IP, we constructed a phylogeny for L. chagosensis for the IP to assess the evolutionary patterns for this species. We generated 188 sequences of L. chagosensis and constructed maximum likelihood and Bayesian inference trees, using concatenated mitochondrial cytochrome oxidase subunit 3 gene (cox3) and nuclear ribosomal RNA gene (28S) markers for the first time. The spatial variation of genetic diversity of L. chagosensis was assessed using a phylogeographic approach. Leucetta chagosensis is composed of five cryptic lineages confined to different biogeographic regions with the specimens found in the Indian Ocean differing significantly from those found in the rest of the IP region. Genetic divergence was particularly high for the cox3 marker, with a low nucleotide diversity but high haplotype diversity for most lineages. This study highlights the need for a sustained effort in studying sponge diversity, boosted by the ongoing discovery of hidden biodiversity among this ecologically important taxon.Rufford FoundationSTIAS Doctoral Fellowshiphttps://www.mdpi.com/1424-2818/12/12/466Publisher's versio