Genetic divergence in lobsters (Crustacea: Palinuridae and Scyllaridae) from the Indian EEZ

The management of exploited species requires the identification of demographically isolated populations that can be considered as independent management units (MUs), failuring in which can lead to over -fishing and depletion of less productive stocks. By characterizing the distribution of genetic variation, population sub structuring can be detected and the degree of connectivity among populations can be estimated. The genetic variation can be observed using identified molecular markers of both nuclear and mitochondrial origin. Hence, the present work was undertaken to study the genetic diversity and population/stock structure in P. homarus homarus and T. unimaculatus from different landing centres along the Indian coast using nuclear (RAPD) and mitochondrial DNA marker tools which will help towards developing management strategies for management and conservation of these declining resources.To make consistent conservation and fisheries management decisions, accurate species identifications are needed. It is also suggested that it is not always desirable to rely on a single sequence for taxonomic identification. Thus, the feasibility of using partial sequences of additional mitochondrial genes like 16SrRNA, 12SrRNA and nuclear 18SrRNA has also been explored in our study. Phylogenies provide a sound foundation for establishing taxonomy. The present work also attempts to reconstruct the phylogeny of eleven species of commercially important lobsters from the Indian EEZ using molecular markers

Slipper lobsters (Scyllaridae) off the southeastern coast of Brazil: relative growth, population structure, and reproductive biology

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Slipper lobster (Crustacea, Decapoda, Scyllaridae) fisheries off the southeastern coast of Brazil: I. Exploitation patterns between 23 degrees 00 ` and 29 degrees 65 ` S

In southeastern Brazil, slipper lobsters (Scyllarides deceptor and S. brasiliensis) are caught by fleets trawling for pink shrimp (Farfantepenaeus brasiliensis and F. paulensis) and pots-and-traps fishing for octopuses (Octopus vulgaris). Eight hundred fifty-six landings of shrimp trawlers and 28 of the octopus fleet were monitored in the Santos region from May 2006 to April 2007. Additional analysis was performed using a database covering the period from 1999 onwards. This study seeks to identify the recent patterns of exploitation of these lobsters with the goal of improving the way towards fishery sustainability. Scyllarides deceptor was the dominant lobster species with 1032 specimens collected, while only three specimens of S. brasiliensis were identified. The area known as the `Farol do Boi` (23 degrees 01`S, 45 degrees 00`W to 25 degrees 00`S, 45 degrees 40`W at 60-135 m deep) showed the highest Catch Per Unit Effort (CPUE). A General Linearized Model (GLM) was used to investigate the factors influencing variations in CPUE in trawl fleets and led to the conclusion that year, month and depth were the most important factors. We detected a significant decrease in the relative abundance of lobsters in the fishing zone despite relatively low fishing effort. Recommendations to protect the lobster resources include taking special precautions in the natural refuge area of the `Farol do Boi`, as an exclusion zone for trawl fleets, and controlling the use of traps longlines to catch octopuses. Concerns about depensatory processes due to the over-exploitation of lobster populations around the world are raised. (C) 2009 Elsevier B.V. All rights reserved.

Isolation and expression analysis of multiple isoforms of putative farnesoic acid O-methyltransferase in several crustacean species

Farnesoic acid O-methyltransferase (FaMeT) is the enzyme responsible for the conversion of farnesoic acid (FA) to methyl farnesoate (MF) in the final step of MF synthesis. Multiple isoforms of putative FaMeT were isolated from six crustacean species belonging to the families Portunidae, Penaeidae, Scyllaridae and Parastacidae. The portunid crabs Portunus pelagicus and Scylla serrata code for three forms: short, intermediate and long. Two isoforms (short and long) were isolated from the penaeid prawns Penaeus monodon and Fenneropenaeus merguiensis. Two isoforms were also identified in the scyllarid Thenus orientalis and parastacid Cherax quadricarinatus. Putative FaMeT sequences were also amplified from the genomic DNA of P. pelagicus and compared to the putative FaMeT transcripts expressed. Each putative FaMeT cDNA isoform was represented in the genomic DNA, indicative of a multi-gene family. Various tissues from P. pelagicus were individually screened for putative FaMeT expression using PCR and fragment analysis. Each tissue type expressed all three isoforms of putative FaMeT irrespective of sex or moult stage. Protein domain analysis revealed the presence of a deduced casein kinase II phosphorylation site present only in the long isoform of putative FaMeT.

Relative pleopod length as an indicator of size at sexual maturity in slipper (Scyllarides squammosus) and spiny Hawaiian (Panulirus marginatus) lobsters

Body size at gonadal maturity is described for females of the slipper lobster (Scyllarides squammosus) (Scyllaridae) and the endemic Hawaiian spiny lobster (Panulirus marginatus) (Palinuridae) based on microscopic examination of histological preparations of ovaries. These data are used to validate several morphological metrics (relative exopodite length, ovigerous condition) of functional sexual maturity. Relative exopodite length (“pleopod length”) produced consistent estimates of size at maturity when evaluated with a newly derived statistical application for estimating size at the morphometric maturation point (MMP) for the population, identified as the midpoint of a sigmoid function spanning the estimated boundaries of overlap between the largest immature and smallest adult animals. Estimates of the MMP were related to matched (same-year) characterizations of sexual maturity based on ovigerous condition — a more conventional measure of functional maturity previously used to characterize maturity for the two lobster species. Both measures of functional maturity were similar for the respective species and were within 5% and 2% of one another for slipper and spiny lobster, respectively. The precision observed for two shipboard collection series of pleopod-length data indicated that the method is reliable and not dependent on specialized expertise. Precision of maturity estimates for S. squammosus with the pleopod-length metric was similar to that for P. marginatus with any of the other measures (including conventional evidence of ovigerous condition) and greatly exceeded the precision of estimates for S. squammosus based on ovigerous condition alone. The two measures of functional maturity averaged within 8% of the estimated size at gonadal maturity for the respective species. Appendage-to-body size proportions, such as the pleopod length metric, hold great promise, particularly for species of slipper lobsters like S. squammosus for which there exist no other reliable conventional morphological measures of sexual maturity. Morphometric proportions also should be included among the factors evaluated when assessing size at sexual maturity in spiny lobster stocks; previously, these proportions have been obtained routinely only for brachyuran crabs within the Crustacea.

Filogeografia e evolução molecular de lagostas sapateiras (Scyllarides spp.) da América do Sul

Nos últimos anos, duas espécies de lagostas sapateiras, Scyllarides brasiliensis e S. deceptor, vêm se destacando nos desembarques pesqueiros de lagostas do Atlântico Sul Ocidental. Para espécies comercialmente importantes, o desenvolvimento de estudos que permitam conhecer a variabilidade e entender a dinâmica populacional é fundamental. Assim, o objetivo do primeiro capítulo desta tese foi avaliar a diversidade genética e a estrutura populacional dessas duas lagostas ao longo de aprox. 2.800 km da costa da América do Sul. Para as análises, foram empregados marcadores mitocondriais (citocromo oxidase I: COI; e a região controle: RC) e marcadores nucleares (13 loci de microssatélites desenvolvidos nesta tese). As duas espécies apresentaram altos níveis de variabilidade (S. deceptor: N = 200, mtDNA: h > 0,841, π > 0,005; microssatélites: He = 0,685; S. brasiliensis: N = 211, He = 0,554), distribuídos homogeneamente entre as localidades (S. deceptor: ΦST < -0,004, ΦCT < 0,016, FST global = 0,001, Dest global = 0,003, FCT < 0,002, P > 0,05, K = 1; S. brasiliensis: FST global = 0,004, Dest global = 0,001, FCT < 0,004, P > 0,05, K = 1). A ausência de estruturação nas duas espécies pode estar relacionada a características biológicas que promovem a conectividade entre localidades geograficamente distantes, como alta fecundidade e alto potencial de dispersão das larvas planctônicas. Além disso, os dados mitocondriais sugerem que a história demográfica de S. deceptor foi marcada por eventos de expansão populacionais e geográficos possivelmente relacionados às condições ambientais favoráveis dos episódios interglaciais do Pleistoceno Médio-Tardio. Diversos estudos têm mostrado que os fenômenos de inserção de regiões mitocondriais no DNA nuclear (NuMts) e heteroplasmia limitam a correta amplificação e identificação dos marcadores mitocondriais. Em estudos filogenéticos e de genética de populações, a presença inadvertida de sequências de diversas origens viola o principio de ortologia, o que pode resultar em inferências evolutivas erradas. Assim, o objetivo do segundo capítulo desta tese foi identificar e caracterizar os possíveis NuMts e sequências heteroplásmicas de três regiões mitocondriais (COI, RC e o gene da subunidade maior do RNA ribossomal: 16S) em quatro espécies do gênero Scyllarides (S. aequinoctialis, S. brasiliensis, S. deceptor e S. delfosi). A clonagem e sequenciamento de extratos de DNA genômico e DNA enriquecido com mtDNA revelaram que os genomas destas espécies podem exibir NuMts (que divergem entre 0,6 e 17,6% do mtDNA) e heteroplasmia (que divergem < 0,2% do mtDNA prevalente). Os NuMts surgiram possivelmente de vários eventos independentes de integração ao núcleo ao longo da história evolutiva do gênero Scyllarides. Dependendo do seu grau de similaridade com o mtDNA, a presença de NuMts nas análises filogenéticas no nível de gênero pode causar superestimativa do número de espécies e alterações nos comprimentos dos ramos e nas relações filogenéticas entre espécies.