Genetic connectivity of two marine gastropods in the Mediterranean Sea: seascape genetics reveals species‐specific oceanographic drivers of gene flow

2021 ◽  
Author(s):  
Violeta López‐Márquez ◽  
Samuel A. Cushman ◽  
José Templado ◽  
Ho Yi Wan ◽  
Helen M. Bothwell ◽  
...  
Keyword(s):  
Gene Flow ◽  
Mediterranean Sea ◽  
Genetic Connectivity ◽  
Marine Gastropods ◽  
The Mediterranean ◽  
Seascape Genetics ◽  
Species Specific

scholarly journals Genetic connectivity between Atlantic bluefin tuna larvae spawned in the Gulf of Mexico and in the Mediterranean Sea

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11568
Author(s):  
Carolina Johnstone ◽  
Montse Pérez ◽  
Estrella Malca ◽  
José María Quintanilla ◽  
Trika Gerard ◽  
...  
Keyword(s):  
Gene Flow ◽  
Gulf Of Mexico ◽  
Mediterranean Sea ◽  
Molecular Ecology ◽  
Bluefin Tuna ◽  
Structured Populations ◽  
Genetic Connectivity ◽  
Homing Behavior ◽  
Atlantic Bluefin Tuna ◽  
The Mediterranean

The highly migratory Atlantic bluefin tuna (ABFT) is currently managed as two distinct stocks, in accordance with natal homing behavior and population structuring despite the absence of barriers to gene flow. Larval fish are valuable biological material for tuna molecular ecology. However, they have hardly been used to decipher the ABFT population structure, although providing the genetic signal from successful breeders. For the first time, cooperative field collection of tuna larvae during 2014 in the main spawning area for each stock, the Gulf of Mexico (GOM) and the Mediterranean Sea (MED), enabled us to assess the ABFT genetic structure in a precise temporal and spatial frame exclusively through larvae. Partitioning of genetic diversity at nuclear microsatellite loci and in the mitochondrial control region in larvae spawned contemporarily resulted in low significant fixation indices supporting connectivity between spawners in the main reproduction area for each population. No structuring was detected within the GOM after segregating nuclear diversity in larvae spawned in two hydrographically distinct regions, the eastern GOM (eGOM) and the western GOM (wGOM), with the larvae from eGOM being more similar to those collected in the MED than the larvae from wGOM. We performed clustering of genetically characterized ABFT larvae through Bayesian analysis and by Discriminant Analysis of Principal Components (DAPC) supporting the existence of favorable areas for mixing of ABFT spawners from Western and Eastern stocks, leading to gene flow and apparent connectivity between weakly structured populations. Our findings suggest that the eastern GOM is more prone for the mixing of breeders from the two ABFT populations. Conservation of this valuable resource exploited for centuries calls for intensification of tuna ichthyoplankton research and standardization of genetic tools for monitoring population dynamics.

scholarly journals Filling in knowledge gaps: Length–weight relations of 46 uncommon sharks and rays (Elasmobranchii) in the Mediterranean Sea

2021 ◽  
Vol 51 (3) ◽  
pp. 249-255
Author(s):  
Athanassios C. Tsikliras ◽  
Donna Dimarchopoulou
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Global Scale ◽  
Biological Information ◽  
Knowledge Gap ◽  
Museum Collections ◽  
Bayesian Hierarchical ◽  
The Mediterranean ◽  
Species Specific ◽  
Bayesian Hierarchical Method

Large sharks and rays are generally understudied in the Mediterranean Sea, thus leading to a knowledge gap of basic biological characteristics that are important in fisheries management and ecosystem modeling. Out of the 76 sharks and rays inhabiting the Mediterranean Sea, the length–weight relations (LWR) are available for 28 (37%) of them, usually for common small-sized species that are not protected and may be marketed. The aim of the presently reported study was to fill in the knowledge gap through the estimation of LWR of rare and uncommon sharks and rays in the Mediterranean Sea using the information from single records or few individuals. The analysis was based on a Bayesian hierarchical method for estimating length–weight relations in fishes that has been recently proposed for data-deficient species or museum collections and uses the prior knowledge and existing LWR studies to derive species-specific LWR parameters by body form. The use of this method was applied to single records of rare and uncommon species and here we report the LWR of 46 uncommon sharks and ray species, 14 of which are first reported LWR at a global scale and 21 are the first reported LWR for the Mediterranean Sea; the remaining 11 species are first time records for the western or eastern Mediterranean regions. Museum collections and sporadic catch records of rare emblematic species may provide useful biological information with the use of appropriate Bayesian methods.

Phylogeography and genetic diversity ofOphidiaster ophidianus(Echinodermata: Asteroidea)—evidence for a recent range expansion in the Azores

2014 ◽  
Vol 94 (7) ◽  
pp. 1475-1484 ◽  
Author(s):  
J. Micael ◽  
P. Rodrigues ◽  
A.C. Costa ◽  
M.J. Alves
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Mediterranean Sea ◽  
North Atlantic ◽  
Range Expansion ◽  
Mitochondrial Gene ◽  
Protected Species ◽  
The Mediterranean

The seastarOphidiaster ophidianusis a vulnerable and protected species in the Mediterranean Sea but is common on North Atlantic islands such as the Azores and Madeira archipelagos. This work presents new insights into the phylogeography and genetic diversity ofO. ophidianusfrom the Azores, based on 67 sequences of the 16S mitochondrial gene and 46 sequences of the nuclear ATP intron 5 gene. Twenty-six samples from the Mediterranean and seven samples from Madeira were used as out-groups. The results revealed that there is a lack of genetic differentiation betweenO. ophidianusfrom the Azores and the out-groups. All, therefore, belong to the same lineage and argue for a fast and recent range expansion of this species into the Azores. Our results also suggest the existence of distinctive periods of strong gene flow followed by periods of either low or non-existent gene flow between the Mediterranean Sea and this archipelago, which could explain the presence of private haplotypes in all studied areas.

scholarly journals Evidence of high genetic connectivity for the longnose spurdog Squalus blainville in the Mediterranean Sea

2015 ◽  
Vol 17 (2) ◽  
pp. 371 ◽  
Author(s):  
V. KOUSTENI ◽  
P. KASAPIDIS ◽  
G. KOTOULAS ◽  
P. MEGALOFONOU
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Structure ◽  
Mediterranean Sea ◽  
Genetic Connectivity ◽  
Middle Pleistocene ◽  
Biological Knowledge ◽  
Shark Species ◽  
High Dispersal ◽  
Dispersal Potential ◽  
The Mediterranean

Squalus blainville is one of the least studied Mediterranean shark species. Despite being intensively fished in several locations, biological knowledge is limited and no genetic structure information is available. This is the first study to examine the genetic structure of S. blainville in the Mediterranean Sea. Considering the high dispersal potential inferred for other squalid sharks, the hypothesis of panmixia was tested based on a 585 bp fragment of the mitochondrial DNA cytochrome c oxidase subunit I gene from 107 individuals and six nuclear microsatellite loci from 577 individuals. Samples were collected across the Ionian, Aegean and Libyan Seas and off the Balearic Islands. Twenty three additional sequences of Mediterranean and South African origin were retrieved from GenBank and included in the mitochondrial DNA analysis. The overall haplotype diversity was high, in contrast to the low nucleotide diversity. Low and non-significant pairwise ΦST and FST values along with a Bayesian cluster analysis suggested high connectivity with subsequent genetic homogeneity among the populations studied, and thus a high dispersal potential for S. blainville similar to other squalids. The historical demography of the species was also assessed, revealing a pattern of population expansion since the middle Pleistocene. These findings could be considered in species-specific conservation plans, although sampling over a larger spatial scale and more genetic markers are required to fully elucidate the genetic structure and dispersal potential of S. blainville.

scholarly journals Filling in knowledge gaps: Length–weight relations of 46 uncommon sharks and rays (Elasmobranchii) in the Mediterranean Sea

2021 ◽  
Vol 51 (3) ◽  
pp. 249-255
Author(s):  
Athanassios C. Tsikliras ◽  
Donna Dimarchopoulou
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Global Scale ◽  
Biological Information ◽  
Knowledge Gap ◽  
Museum Collections ◽  
Bayesian Hierarchical ◽  
The Mediterranean ◽  
Species Specific ◽  
Bayesian Hierarchical Method

Large sharks and rays are generally understudied in the Mediterranean Sea, thus leading to a knowledge gap of basic biological characteristics that are important in fisheries management and ecosystem modeling. Out of the 76 sharks and rays inhabiting the Mediterranean Sea, the length–weight relations (LWR) are available for 28 (37%) of them, usually for common small-sized species that are not protected and may be marketed. The aim of the presently reported study was to fill in the knowledge gap through the estimation of LWR of rare and uncommon sharks and rays in the Mediterranean Sea using the information from single records or few individuals. The analysis was based on a Bayesian hierarchical method for estimating length–weight relations in fishes that has been recently proposed for data-deficient species or museum collections and uses the prior knowledge and existing LWR studies to derive species-specific LWR parameters by body form. The use of this method was applied to single records of rare and uncommon species and here we report the LWR of 46 uncommon sharks and ray species, 14 of which are first reported LWR at a global scale and 21 are the first reported LWR for the Mediterranean Sea; the remaining 11 species are first time records for the western or eastern Mediterranean regions. Museum collections and sporadic catch records of rare emblematic species may provide useful biological information with the use of appropriate Bayesian methods.

scholarly journals Genetic diversity increases with depth in red gorgonian populations of the Mediterranean Sea and the Atlantic Ocean

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6794 ◽  
Author(s):  
Joanna Pilczynska ◽  
Silvia Cocito ◽  
Joana Boavida ◽  
Ester A. Serrão ◽  
Jorge Assis ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Thermal Stress ◽  
Gene Flow ◽  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Environmental Conditions ◽  
Heat Waves ◽  
Genetic Erosion ◽  
Linear Pattern ◽  
The Mediterranean

Background In the ocean, the variability of environmental conditions found along depth gradients exposes populations to contrasting levels of perturbation, which can be reflected in the overall patterns of species genetic diversity. At shallow sites, resource availability may structure large, persistent and well-connected populations with higher levels of diversity. In contrast, the more extreme conditions, such as thermal stress during heat waves, can lead to population bottlenecks and genetic erosion, inverting the natural expectation. Here we examine how genetic diversity varies along depth for a long-lived, important ecosystem-structuring species, the red gorgonian, Paramuricea clavata. Methods We used five polymorphic microsatellite markers to infer differences in genetic diversity and differentiation, and to detect bottleneck signs between shallow and deeper populations across the Atlantic Ocean and the Mediterranean Sea. We further explored the potential relationship between depth and environmental gradients (temperature, ocean currents, productivity and slope) on the observed patterns of diversity by means of generalized linear mixed models. Results An overall pattern of higher genetic diversity was found in the deeper sites of the Atlantic Ocean and the Mediterranean Sea. This pattern was largely explained by bottom temperatures, with a linear pattern of decreasing genetic diversity with increasing thermal stress. Genetic differentiation patterns showed higher gene flow within sites (i.e., shallow vs. deeper populations) than between sites. Recent genetic bottlenecks were found in two populations of shallow depths. Discussion Our results highlight the role of deep refugial populations safeguarding higher and unique genetic diversity for marine structuring species. Theoretical regression modelling demonstrated how thermal stress alone may reduce population sizes and diversity levels of shallow water populations. In fact, the examination of time series on a daily basis showed the upper water masses repeatedly reaching lethal temperatures for P. clavata. Differentiation patterns showed that the deep richer populations are isolated. Gene flow was also inferred across different depths; however, not in sufficient levels to offset the detrimental effects of surface environmental conditions on genetic diversity. The identification of deep isolated areas with high conservation value for the red gorgonian represents an important step in the face of ongoing and future climate changes.

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