Papers by Lorenzo Rojas Bracho
Frontiers in Marine Science
The distribution of wide-ranging cetacean species often cross national or jurisdictional boundari... more The distribution of wide-ranging cetacean species often cross national or jurisdictional boundaries, which creates challenges for monitoring populations and managing anthropogenic impacts, especially if data are only available for a portion of the species’ range. Many species found off the U.S. West Coast are known to have continuous distributions into Mexican waters, with highly variable abundance within the U.S. portion of their range. This has contributed to annual variability in design-based abundance estimates from systematic shipboard surveys off the U.S. West Coast, particularly for the abundance of warm temperate species such as striped dolphin, Stenella coeruleoalba, which increases off California during warm-water conditions and decreases during cool-water conditions. Species distribution models (SDMs) can accurately describe shifts in cetacean distribution caused by changing environmental conditions, and are increasingly used for marine species management. However, until ...
Zoology 2017: 'Genotype-phenotype map: from model systems to ecosystems': Benelux Congress of Zoology, Jun 6, 2017
Gray Whales and Climate Change: Sentinels of the North Pacific / Arctic Ecosystems Monday, Novemb... more Gray Whales and Climate Change: Sentinels of the North Pacific / Arctic Ecosystems Monday, November 17, 2008 Held in Conjunction with the ACS Conference Hosted by Sue Moore and Steven Swartz Sponsored by the Pacific Life Foundation
We present an analysis of geographic variation in the diversity of marine mammals at the Mexican ... more We present an analysis of geographic variation in the diversity of marine mammals at the Mexican Pacific and surrounding waters looking to yield useful elements for the conservation of these animals as around them, important issues on the use of marine ecosystems are discussed. From the year 1981 to 2006, 54 cruises were made to register a total of 1582 sightings of 31 marine mammal species. We found a qualitative distinction of marine mammals from the North Pacific as well as a primary biogeographic affinity of the Gulf of California with the oceanographic transition zone and the Tropical Pacific. Community structure of marine mammals in the boreal frontier of the oceanographic transition zone is unstable while such structure in the Tropical Pacific appears stable in large and mesoscale. Contrast between effects of climate change on species associated with upwelling and tropical species, shows differences in populational responses of abundance and differences in the formation of coastal and offshore taxa but similarities in populational responses of geographic subdivision. These similar responses consist of populational fractioning associated to climate warming, Thereafter, we have deduced the concern about how the ongoing biosphere warming, in combination with other negative anthropogenic effects, may enhance extinction risk in species with a fragmented population structure.
The date of the overall highest wintertime counts of adult gray whales (Eschrichtius robustus) in... more The date of the overall highest wintertime counts of adult gray whales (Eschrichtius robustus) in Laguna San Ignacio, Baja California Sur, Mexico occurred as early as 16 February (2013) and as late as 28 February (2008) during the years 2007 to 2013. The earliest date of the highest counts of gray whales in Laguna Ojo de Liebre occurred on 15 February (2010) and as late as 5 March (2007 and 2012). The number of gray whales utilizing Laguna San Ignacio increased during the 2011 to 2013 winter breeding seasons compared to lower and declining counts of whales observed in this lagoon from 2007 to 2010. The highest counts of adult gray whales (i.e., single adults and female-calf pairs combined) were 320 adult whales in 2011, 268 adult whales in 2012, and 272 adult whales in 2013. The highest counts of single whales were 261 single whales in 2011, 205 single whales in 2012, and 214 single whales in 2013. The highest counts of female-calf pairs were 133 female-calf pairs in 2011, 110 femal...
Marine Environmental Research, 2010
Journal of Heredity, 2008
Accurate knowledge of population structure in cetaceans is critical for preserving and managing b... more Accurate knowledge of population structure in cetaceans is critical for preserving and managing breeding habitat, particularly when habitat is not uniformly protected. Most eastern gray whales return to their major breeding range each winter along the Pacific coast of Baja California, Mexico, concentrating in 3 major calving lagoons, but it is unknown whether genetic differences exist between lagoons. Previous photo-identification studies and genetic studies suggest that gray whales may return to their natal lagoons to breed, potentially resulting in the buildup of genetic differences. However, an earlier genetic study used only one genetic marker and did not include samples from Bahia Magdalena, a major calving lagoon not currently designated as a wildlife refuge. To expand on this previous study, we collected genetic data from the mitochondrial control region (442 bp) and 9 microsatellite markers from 112 individuals across all 3 major calving lagoons. Our data suggest that migration rates between calving lagoons are high but that a small but significant departure from panmixia exists between Bahia Magdalena and Laguna San Ignacio (Fisher's Exact test, P , 0.0001; F ST 5 0.006, P 5 0.025). Coalescent simulations show that the lack of extensive population structure may result from the disruption of structure due to whaling. Another possibility is that rates of migration have always been high (.10% per generation). In addition, microsatellite data showed evidence of a severe population bottleneck. Eastern gray whales are still recovering from the impacts of whaling on their breeding grounds, and these populations should be protected and monitored for future genetic changes.
Environmental Science and Pollution Research, 2014
In this work, a suite of diagnostic biomarkers was applied to seven cetacean species to evaluate ... more In this work, a suite of diagnostic biomarkers was applied to seven cetacean species to evaluate the role of the feeding habits and migratory behavior in the toxicological status of these species from the Gulf of California, Mexico. We investigate the interspecific differences in cytochrome P450 1A1 and 2B (CYP1A1 and CYP2B, respectively), aryl hydrocarbon receptor and E2F transcription factor 1 and the contaminants levels [organochlorine compounds, polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs)] in four odontocete species (common bottlenose dolphin, long-beaked common dolphin, sperm whale and killer whale) and three mysticete species (blue whale, fin whale, and Bryde's whale) using skin biopsy. Differences in contaminant levels and molecular biomarker responses between the odontocete and mysticete species have been pointed out. The canonical discriminant analysis on principal component analysis factors, performed to reveal clustering variables, shows that odontocete are characterised by the highest levels of lipophilic contaminants compared to the mysticete, with the highest levels of polychlorinated biphenyls, dichlorodiphenyltrichloroethanes and PBDEs detected in killer whale and the lowest levels in Bryde's whale. The biomarker data show interspecific differences amongst the seven species, revealing highest CYP1A and CYP2B protein levels in the mysticete fish-eating species (Bryde's whale). In conclusion, three main factors seem to regulate the biomarker responses in these species: (a) the inductive ability of persistent organic pollutants and PAHs; (b) the different evolutionary process of the two CYPs related to the different feeding habits of the species; (c) the migratory/resident behaviour of the mysticete species in this area.
Top: Nick Tregenza with the first C-POD. This POD was used in Vaquita Expedition 2008. Bottom: Wo... more Top: Nick Tregenza with the first C-POD. This POD was used in Vaquita Expedition 2008. Bottom: Workshop participants: StandingTomonari Akamatsu, Jay Barlow, Nick Tregenza, René Swift, Armando Jaramillo Legoretta, Paloma Ladrón de Guevara; ...
Capital natural de …, 2008
E ste cap tulo presenta la mayor parte de los resultados que se han publicado acerca de la cantid... more E ste cap tulo presenta la mayor parte de los resultados que se han publicado acerca de la cantidad y la distribuci n de la variaci n gen tica en especies mexicanas usando marcadores moleculares (desde aloenzimas hasta secuencias de adn). La ...
Citation for published version (APA): Ben Chehida, Y., Thumloup, J., Schumacher, C., Harkins, T.,... more Citation for published version (APA): Ben Chehida, Y., Thumloup, J., Schumacher, C., Harkins, T., Aguilar, A., Borrell, A., Ferreira, M., RojasBracho, L., Robertson, K. M., L. Taylor, B., A. Víkingsson, G., Sabot, F., Weyna, A., Romiguier, J., A. Morin, P., & Fontaine, M. (2019). Evolutionary history of the porpoise family (Phocoenidae) a perspective from mitogenomes and whole genomes. bioRxiv, 241. https://doi.org/10.1101/851469
CSV file created from dataset containing days of effort per year and site
R file with implementation of Spatial Model for OpenBUGS
R file implementing model averaging
R file with summary specification for Mixture Model
CSV file created from dataset containing number of vaquita clicks detected per day per site
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Papers by Lorenzo Rojas Bracho