Population connectivity plays significant roles on both evolutionary and ecological time-scales; however, quantifying the magnitude and pattern of ex- change between populations of marine organisms is hindered by the difficulty of tracking the trajectory and fate of propagules. We explored biophysical correlates of population substructure to determine how well pelagic larval duration (PLD) correlates with population genetic estimates of connectivity in a sample of 300 published studies drawn pseudo-randomly from about 1600 hits on electronic searches. In direct contrast to the general expectation of a strong correlation, we find that average PLD is poorly correlated (r 2 < 0.1) with genetic structure (FST). Furthermore, even this weak correlation is anchored by non-pelagic dispersal, because removal of the zero PLD class (direct developers) from the analy- sis resulted in a non-significant relationship between FST and PLD. For species in which minimum, maximum, and mean PLDs were available, it is noteworthy that both minimum and maximum PLDs are better corre- lated with FST than the mean larval duration, which has been used in all such previous studies. A 3-way AN- COVA reveals that genetic marker class (allozymes, microsatellites, and mitochondrial DNA sequences), as opposed to habitat or swimming ability, explain most of the variation in FST (F = 7.113, df = 2, p = 0.001), with higher values of FST obtained from mtDNA than with either microsatellites or allozymes (which were not sig- nificantly different). Our meta-analysis refutes recent reviews and conventional wisdom that PLD is a good predictor of the magnitude of gene flow and geo- graphic scale of population structure in marine systems.

/pdf/population-genetics-larval-dispersal-and-connectivity-in-148msamk1s.pdf

Population genetics, larval dispersal, and connectivity in marine systems

Handbook of enzyme electrophoresis in human genetics

To estimate response to selection and realized heritability for shell height, a one-generation selection was performed in the Pacific oyster Crassostrea gigas using three stocks from China (stock C), Japan (stock J), and Korea (stock K). Applying about the same intensity of selection in the upward direction, three selected and three control lines were created, which were reared under the same environmental conditions at larvae, spat, and grow-out stages. Stock C and stock J showed significantly higher response to selection and realized heritability than stock K at spat and grow-out stages (P < 0.05). At harvest on day 360, the selected lines of stocks C, J, and K were 12.2, 12.2, and 7.9% larger than their control lines, respectively, for shell height. When averaged across the grow-out period, the genetic gain for stocks C, J, and K was 13.2 ± 1.2, 13.2 ± 1.0, and 7.2 ± 0.7%, respectively, and realized heritability was 0.334 ± 0.028, 0.402 ± 0.024 and 0.149 ± 0.027, respectively. The relatively high realized heritability estimate obtained for stock C and stock J indicates that there is genetic variation in the two stocks and that selective breeding by mass selection is very promising.

Selection response and realized heritability for growth in three stocks of the Pacific oyster Crassostrea gigas

We assessed the genetic structure of the giant kelp Macrocystis pyrifera across a broad latitudinal range along the southeastern Pacific coast (SEP). Specifically we analyzed the concor- dance of putative biogeographic breaks with genetic discontinuities and the effect of historical and contemporary events on the genetic pattern of this important seaweed. Mitochondrial DNA and sin- gle-strand DNA conformation polymorphism (SSCP) analysis for a total of 730 samples were carried out. Only 5 haplotypes were found among individuals collected along 4800 km of coastline, with very low haplotype diversity and a shallow genealogy compared with other macroalgal species. Some phylogeographic disjunctions in M. pyrifera were found to correspond roughly to established biogeo- graphic breaks. On the southern coast we found a genetic break at 42°S (Chiloe Island) coincident with a well-known biogeographic boundary, while the genetic break found between samples in cen- tral/northern Chile (33° S) does not correspond to any known biogeographic breaks in other brown algae, but does reflect a break associated with other marine taxa. The low genetic diversity in north- ern Chile may be related to contemporary events (e.g. El Nino Southern Oscillation) while in south- ern Chile the haplotype distribution may reflect the effect of historical events (Last Glacial Maximum; LGM). Additionally, we compared the SEP data with samples from some of the subantarctic islands and New Zealand. The results showed shared haplotypes among some of the subantarctic islands and southern-central Chile, suggesting a recent colonization of the subantarctic region. The high dis- persal potential of kelp rafts may also help to explain the low genetic diversity observed. We conclude that both present and historic events are responsible for the genetic structure of M. pyrifera along the SEP.

/pdf/genetic-structure-of-the-giant-kelp-macrocystis-pyrifera-4c8pk4mvxr.pdf

Genetic structure of the giant kelp Macrocystis pyrifera along the southeastern Pacific

Fish and seafood substitution has become an important concern in domestic and international marketplaces, in part due to increased international trade, per capita seafood consumption, and production of processed foods. In many cases, seafood substitution is a form of economic deception, where highly prized species are substituted with those of lesser value. To prevent illegal species substitution, a number of DNA-based methods have been developed to detect fish and seafood species in commercial products. These methods, along with common gene targets, have been reviewed previously in this journal. The current article is meant to build upon earlier discussions by providing a comprehensive review of the application of these DNA-based methods to the discovery of fish and seafood substitution on the commercial market. Popular food uses, potential substitution cases, and peer-reviewed research articles published to date are discussed for all major species groups of concern, including flatfish, gadoids, scombroids, salmonids, percoids, sturgeons, sharks, eels, and bivalves. The use of DNA-based methods to monitor commercial whale meat products is also reviewed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2009.00073.x

Application of DNA‐Based Methods to Identify Fish and Seafood Substitution on the Commercial Market

The heritability of larval size is estimated in Mytilus chilensis, based on a nested design, involving 95 full-sib and 19 half-sib families (19 males each mated to 5 separated females) grown under controlled laboratory conditions. The half-sib heritability estimates at 10, 25 and 40 days for larval and spat shell height ranged between 0.38±0.33 and 0.84±0.45, suggesting that selection for shell size would be effective.

Heritability estimates of larval and spat shell height in the Chilean blue mussel (Mytilus chilensis Hupe 1854) produced under controlled laboratory conditions

The Chilean blue mussel Mytilus chilensis is an important commercial species. However, little has been published on the population genetics of this species, despite the need to implement management and conservation policies. Randomly amplified polymorphic DNA-polymerase chain reaction analysis was used to estimate genetic variation within and between eight natural populations along the whole range of its Chilean natural distribution (ca. 1900 km from Arauco (VIII Region) to Punta Arenas (XII Region)). The values of Nei's unbiased genetic distance, D (0.030–0.107), among populations were small, despite the large geographic separation. A mantel test using 50 000 randomizations showed evidence for a significant correlation (r=0.74, P<0.05) between genetic and geographic (coastal) distance. Punta Arenas population was the most genetically differentiated from the others, although the scale of differentiation was not large (D=0.076–0.107). The levels of gene flow (Nm=1.55) found in this study prevent differentiation among populations by genetic drift. This is the result of the long-lived planktotrophic larvae of M. chilensis, which provides this species with considerable dispersal ability throughout its range, which is favoured by the ocean currents along the Chilean coast. A restricted larval dispersal towards the north due to the Cape Horn Current derived from the West Wind Drift could be the cause of the higher genetic differentiation of Punta Arenas population from the northern populations. For management purposes of the M. chilensis fishery, the results provide no evidence for discrete stocks, with the possible exception of the Punta Arenas population. The present study provides the baseline data in order to continue further characterization of these mussel populations, considering the great increase in aquaculture of this species.

The genetic structure of Mytilus chilensis (Hupé 1854) populations along the Chilean coast based on RAPDs analysis

Genetic differentiation in the Chilean blue mussel Mytilus chilensis (Hupe 1854) was investigated based on the variation in the allozyme frequencies of Pgm, Gpi, Icd, Me, Gsr, Lap and Pep in eight samples collected along 1800 km from Arauco (VIII Region) to Punta Arenas (XII Region). Despite the large geographic separations, values of Neis unbiased genetic distance, D (0.004-0.048) and standardised genetic variation among populations, Fst (0.011-0.055) were small. The levels of gene flow (Nm = 8) found in this study prevent the effect of differentiation among populations by genetic drift. This findings indicate that its long-lived planktotrophic larvae provides this species with considerable dispersal ability throughout its range which is favoured by the ocean currents along the chilean coast. In terms of management of the M. chilensis fishery, the results provide no evidence for discrete stocks, with the possible exception of the Punta Arenas population. Considering the intensive aquaculture activities with this species the present study provide preliminary data which can be used as a baseline for further characterization and /or monitoring these mussel populations.

/pdf/allozymic-variation-and-differentiation-in-the-chilean-blue-f0w5jp8p44.pdf

Allozymic variation and differentiation in the chilean blue mussel, Mytilus chilensis, along its natural distribution

The Chilean blue mussel formerly Mytilus chilensis Hupe 1854, have been recently subject to a taxonomic revision using electrophoretically generated genetic data concluding that mussels from South America should be included tentatively in Mytilus edulis. The molecular genetic characterization (restriction fragment length polymorphism) of samples from 8 natural populations along the whole natural distribution of the Chilean blue mussel using 3 PCR-based nuclear DNA markers (ITS, Glu-5 and Me) was carried out. One of the markers (ITS) showed a similar banding pattern than M. edulis and M. galloprovincialis, whereas the other markers (Glu-5 and Me) showed a specific banding pattern found only in M. galloprovincialis. Also, a very low number (3.9%) of mussel hybrids (M. edulis–M. galloprovincialis) using two codominant markers was detected in the present study. The molecular evidence suggests that M. galloprovincialis is present in the southern coast of Chile, whereas no evidence for the occurrence o...

Molecular characterization of the chilean blue mussel (mytilus chilensis hupe 1854) demonstrates evidence for the occurrence of mytilus galloprovincialis in southern chile

The oyster parental stock was taken from the 1998 natural spatfall from the wild population of Ostrea chilensis at the Quempillen River Estuary, located at C...

/pdf/respuesta-a-la-seleccion-genetica-para-crecimiento-en-79ktzum9m6.pdf

Respuesta a la selección genética para crecimiento en juveniles de Ostrea chilensis Philippi (Bivalvia: Ostreidae), mantenidos en condiciones de laboratorio

Johana A. Ojeda

Papers

Heritability estimates of larval and spat shell height in the Chilean blue mussel (Mytilus chilensis Hupe 1854) produced under controlled laboratory conditions

The genetic structure of Mytilus chilensis (Hupé 1854) populations along the Chilean coast based on RAPDs analysis

Allozymic variation and differentiation in the chilean blue mussel, Mytilus chilensis, along its natural distribution

Molecular characterization of the chilean blue mussel (mytilus chilensis hupe 1854) demonstrates evidence for the occurrence of mytilus galloprovincialis in southern chile

Respuesta a la selección genética para crecimiento en juveniles de Ostrea chilensis Philippi (Bivalvia: Ostreidae), mantenidos en condiciones de laboratorio