Jorge de la Rosa-Vélez

Population structure of purple sea urchin Strongylocentrotus purpuratus along the Baja California peninsula

Purple sea urchin Strongylocentrotus purpuratus is fished from British Columbia, Canada to Punta Baja, Mexico. The North American population has been divided into northern and southern fishery stocks at the break of Point Conception, but little is known about its southernmost distribution along the Mexican Pacific coast of the Baja California peninsula. In this study purple sea urchin populations in six sites along the Baja California peninsula were analyzed using mitochondrial deoxyribonucleic acid restriction fragment length polymorphism (mtDNA RFLP). A homogeneous distribution of three common haplotypes among all sites was observed. A significant FST value, however, indicated genetic structure mainly due to the haplotype array in San Miguel, Isla Todos Santos and Punta Baja sites, which were characterized by having high haplotype diversity and several unique haplotypes. Homogeneous distribution of haplotypes along the peninsula could have been influenced by the unidirectional California Current system, flowing north to south. Unique haplotypes in Punta Baja and the structure found could be the result of local oceanographic features specific to this major upwelling zone. It may be necessary to consider the Punta Baja populations individually when managing the purple sea urchin fishery in Baja California, as they show signs of being a unique stock.

Mitochondrial haplotype variation in wild trout populations (Teleostei: Salmonidae) from northwestern Mexico

The variation and composition of Mexican wild trout mitochondrial DNA haplotypes throughout northwestern Mexico was determined by means of polymerase chain reaction–restriction fragment polymorphism analysis (PCR–RFLP), of one region of mitochondrial DNA between cytochrome b and the D-loop. This analysis was based on 261 specimens taken in 12 basins and four hatcheries from northwestern Mexico. From 23 haplotypes, 15 wild trout haplotypes were identified and classified in four groups: (1) one restricted to Nelson’s trout (Oncorhynchus mykiss nelsoni), (2) four restricted to Río Mayo and RíoYaqui trout (O. mykiss sspp.), (3) six to Mexican golden trout (O. chrysogaster) with two subgroups, and (4) one exclusive to Río Piaxtla trout. Distributions of native haplotypes broadly overlap the distribution of non-native hatchery rainbow trout reflecting the historical management of introductions of exotic rainbow trout and the artificial transference of these trout among basins.

The complete mitochondrial genomes of the yellowleg shrimp Farfantepenaeus californiensis and the blue shrimp Litopenaeus stylirostris (Crustacea: Decapoda).

Mitochondria play key roles in many cellular processes. Description of penaeid shrimp genes, including mitochondrial genomes are fairly recent and some are focusing on commercially important shrimp as the Pacific shrimp Litopenaeus vannamei that is being used for aquaculture not only in America, but also in Asia. Much less is known about other Pacific shrimp such as the yellowleg shrimp Farfantepenaeus californiensis and the blue shrimp Litopenaeus stylirostris. We report the complete mitogenomes from these last two Pacific shrimp species. Long DNA fragments were obtained by PCR and then used to get internal fragments for sequencing. The complete F. californiensis and L. stylirostris mtDNAs are 15,975 and 15,988 bp long, containing the 37 common sequences and a control region of 990 and 999 bp, respectively. The gene order is identical to that of the tiger shrimp Penaeus monodon. Secondary structures for the 22 tRNAs are proposed and phylogenetic relationships for selected complete crustacean mitogenomes are included. Phylogenomic relationships among five shrimp show strong statistical support for the monophyly of the genus across the analysis. Litopenaeus species define a clade, with close relationship to Farfantepenaeus, and both clade with the sister group of Penaeus and Fenneropenaeus.

Gene expression kinetics of the yellow head virus in experimentally infected Litopenaeus vannamei

Abstract The yellow head virus (YHV) has been reported to be one of most pathogenic viruses for cultivated shrimp; however, serious problems have only been reported in farms in south and southeastern Asian. Recently, a YHV strain was detected in Litopenaeus vannamei cultivated in Mexican farms that lacked virus‐associated mortalities or epizooties, and the animals were apparently healthy. The identity of the virus was confirmed by sequencing replicative and structural protein‐encoding regions and comparing with homologous virus sequences. Phylogenic relationships and genetic distances were also determined and, although some differences were observed, an influence on virulence was uncertain. In addition, the expression levels of several transcripts (3CLPRO, POL, GP64 and GP116) were evaluated by quantitative real‐time polymerase chain reaction during an experimental infection. Although the transcript showed varying kinetics, viral genes were expressed in infected L. vannamei, demonstrating the replicative capability of this YHV strain.

Biometric and Allozymic Characterization of Three Coastal and Inland Killifish Populations (Pisces: Fundulidae) from the Peninsula of Baja California, Mexico

Type localities and/or central populations of coastal and inland killifishes along the peninsula of Baja California were sampled to survey the biometric and allozymic relationships among them. The standard stepwise discriminatory function analysis of biometric characters classified organisms into three well distinctive groups (p < 0.001 ). The number of scales in the lateral series successfully split the species, while the caudal length/standard length ratio did so between subspecies. Two diagnostic loci (PROT-2 * and AAT-2 * ) segregated private alleles in each taxon. Fundulus lima showed lower genetic variability levels than F. parvipinnis spp., in both polymorphism (18.8% in F. lima vs. 25.0% in F. parvipinnis spp.) and expected heterozygosity (0.060 in F. lima vs 0.099 in F. p. brevis and 0.089 in F. p. parvipinnis). The reduced genetic variability in the threatened species F. lima may be related to its evolutionary history. Neis genetic distance between F. lima and F. p. parvipinnis was 0.247, while 0.075 between F. parvipinnis spp.

Lack of genetic evidence for the subspeciation of Pisaster ochraceus (Echinodermata: Asteroidea) in the north-eastern Pacific Ocean

The existence of two Pisaster ochraceus subspecies has been proposed; one located northwards ( P. ochraceus ochraceus) and the other southwards (Pisaster ochraceus segnis ) from Point Conception. We used polymerase chain reaction–restriction fragment length polymorphism of the CO I and CO III mitochondrial genes to assess the degree of population structure from 126 samples collected along the western coast of North America, from Vancouver, Canada to Punta San Carlos, of Baja California, Mexico. The genetic structure was tested through molecular analysis of variance and by Monte Carlo simulations of the original data set. The phylogeographical pattern was deduced from a minimum spanning network analysis. No genetic structure was detected. Instead, a high degree of genetic homogeneity along the species distribution was evident from haplotype frequencies at each location. Two haplotypes, Po1 and Po5 , were predominant along the distribution and were considered ancestral because of their central position in the minimum spanning network. Since Pisaster ochraceus depicts a planktotrophic larval stage with very long duration before settlement, it seems to be able to surpass the biogeographical boundary that limits other species around Point Conception, thereby maintaining homogeneity of its genetic pool. Results of this study recognize P. ochraceus as a single species.

Ten new microsatellite markers for the buttonwood mangrove (Conocarpus erectus L., Combretaceae).

We present 10 microsatellite markers for the buttonwood mangrove, Conocarpus erectus, a wide‐range mangrove associate species. Polymorphism was assessed among individuals from six different populations along the Pacific Coast of Mexico and Costa Rica, as well as in two individuals from the Yucatan Peninsula in the Atlantic. The number of alleles detected in the Pacific ranged from two to five. All loci amplified in the Yucatan samples and seven loci revealed a unique Atlantic allele. These markers will be useful for studies in the conservation of the species and to study the basic biology of C. erectus.

Interbreeding between two populations of Acartia californiensis (Copepoda: Calanoida): a laboratory study

Interbreeding between two populations (Estero de Punta Banda, Baja California, Mexico (PB) and Mission Bay, California, USA (MB)) was tested using the live progeny (nauplii) of the marine calanoid copepod Acartia californiensis , in a male to female ratio of 3:1. The laboratory conditions were 18±2°C and a 12:12 h L:D cycle, during an experimental period of one week. The first filial progeny (F 1 ) present in the replicates were used in four combinational experiments (non-hybrids: PB-PB and MB-MB, and hybrids: PB-MB and MB-PB). To investigate the production of the F 2 generation, males and females were selected from F 1 and 16 combinational experiments were conducted with five replicates each (non-hybrids: PBPB-PBPB and MBMB-MBMB, and hybrids: PBPB-MBMB, PBPB-PBMB, PBPB-MBPB, MBMB-PBPB, MBMB-PBMB, MBMB-MBPB, PBMB-PBPB, PBMB-MBMB, PBMB-PBMB, PBMB-MBPB, MBPB-PBPB, MBPB-MBMB, MBPB-PBMB and MBPB-MBPB). Statistical analysis for F 1 showed no significant differences of the mean for live progeny between the non-hybrids and hybrids and between non-hybrids, but a significant difference between hybrids was found. For F 2 , the mean live progeny between non-hybrids and hybrids, between hybrids and between non-hybrids was found to be non-significant. These results show successful interbreeding between the populations studied.