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Extended Library for Visual Interactive Applications (ELVIA) is a programming tool developed and used by the two most important public universities in the Baja California peninsula in México. ELVIA provides a Java class framework that helps novice students of programming to automatically generate the graphical user interface of interactive applications, focusing in the classes and objects that compose the applications. This paper describes ELVIA, some application examples and experiences applying this programming tool in introductory programming courses. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 214-220, 2012 [ABSTRACT FROM AUTHOR]

We analysed the floristic turnover, or β-diversity patterns, of woody legumes in Baja California, the 1300 km long peninsula in NW Mexico. From the specimen labels of nine herbaria, we digitized 4205 records from 78 species and projected them onto a grid of 205 cartographic cells (20 longitude&tims; 15' latitude). We found that the E-W turnover from the Pacific coast to the Sea of Cortés was high (ca, 60% change from one cell to the next) and that it was significantly associated with topographic variation across the peninsula. An analysis of between-site similarities showed that floristic regions in the peninsula have well defined boundaries, and that floristic similarities tend to extend for long distances along the coastal corridor of the Sea of Cortés, Finally, a numerical classification of Baja California based on the floristic attributes of the cells separated the peninsula into five well defined regions that coincide very closely with regionalizations, previously proposed by various authors using descriptive methods, and with the areas of endemism described for the peninsula in a previous paper. We conclude that the ecological regions of woody legumes in the peninsula clearly reflect the two main environmental forces that act on it, namely, the 1300 km long temperate-tropical climatic gradient and the dramatic E-W gradient running from the Pacific Ocean ca, 100 km across the mountain range into the Sea of Cortés. [ABSTRACT FROM AUTHOR]

In this work, we report new chemical and isotopic data (3He/4He, δ13CCO2, δ13CCH4, and δDCH4) from poorly or previously unstudied hydrothermal and magmatic gases that are emitted along the eastern coast of the Baja California Peninsula (BCP). High 3He/4He values (up to ~7 Ra) characterize the magmatic gases, while lower ratios (≤1.6 Ra) characterize hydrothermal springs. We infer that the mantle beneath the BCP could be Mid‐ocean‐ridge basalt (MORB)‐likes, as in the rift within the Gulf of California, or it may reflect contamination from C‐rich sediment during paleo‐subduction of the Farallon plate. During their ascent, through the crust, mantle/magmatic gases mix with CO2‐ and 4He‐rich fluids, thus forming CO2‐rich hydrothermal gases. These hydrothermal gases undergo partial dissolution of CO2 in shallow waters under different temperature and pH conditions, which further modifies their composition. Thermogenic and possibly abiogenic sources of methane are present only in magmatic gases from the BCP. Secondary methane oxidation (microbial/inorganic) processes are proposed for some hydrothermal gases, which are extremely enriched in heavy isotopes. Finally, we argue that the hydrothermal gases that are emitted from the BCP have variable percentages of mantle contribution, indicating the presence of lithospheric faults enhancing the rise of mantle fluids also in areas where volcanism is absent. Key Points: Based on 3He/4He, the gases emitted from the Baja California Peninsula have two origins: magmatic and hydrothermalThe hydrothermal gases contain variable mantle contributions that indicate the presence of active faultsThe mantle beneath the Baja California Peninsula could be contaminated from subducted C‐rich sediment [ABSTRACT FROM AUTHOR]

Evaluating historical changes in the exploitation of marine organisms is a key challenge in fisheries ecology and marine conservation. In the Eastern Pacific, marine turtles were exploited for millennia before systematic monitoring began <50 years ago. Using ethnographic and historical data, we generated a detailed reconstruction of the East Pacific green sea turtle ( Chelonia mydas) fishery in Mexico's Baja California peninsula from 1700 to 1990. Sea turtles from the region's important feeding areas were a staple food source from the earliest phases of human occupation, dating back at least 12,000 years. In contrast with regions such as the Caribbean, small human populations and limited market access resulted in apparently sustainable turtle harvests until the second half of the 20th century. We found that the estimated annual catches between 1960 and 1980 exceeded the estimated annual catches of the previous 250 years by an order of magnitude, leading to the collapse of the fishery and the depletion of the green turtle population. A total ban on sea turtle captures in 1990, comprehensive nesting beach protection, and significant conservation efforts resulted in increases in breeding females on nesting beaches and catch rates in scientific monitoring on main feeding grounds since the early 2000s. This provides a positive outlook for this once-depleted population segment. Although further research is needed to evaluate current conservation status, we have identified a date, between 1950 and 1960, which can serve as a reliable temporal reference for future evaluations of historical baseline abundance in this region. [ABSTRACT FROM AUTHOR]

The complex geological and ecological processes that have generated high levels of biodiversity and endemism in the Baja California Peninsula have been the subject of intensive study. However, relatively little is known about phylogeography of the iconic endemic palm species of this region. We therefore analyzed a total of 2,294 bp of chloroplast and 738 bp of nuclear sequence data in 169 samples of five native palm species from Baja California, Sonora and Guadalupe Island. We found that Washingtonia and Brahea palms had low levels of genetic diversity and were highly structured, with the majority of species and major geographic regions being characterized by distinct haplotypes. We also found strong support for currently recognized species in Washingtonia, but our results were less clear cut for Brahea due to haplotype sharing. Furthermore, patterns of population structure were broadly consistent with historical vicariant events such as the inundation of the Isthmus of La Paz, the formation of the Sea of Cortez, and the more recent colonization and isolation of Guadalupe Island's palms. Our findings contribute toward a growing appreciation of the complexity of plant responses to past geological changes and also provide valuable baseline genetic data on relict American palm species. [ABSTRACT FROM AUTHOR]

Coastal habitats are crucial to pinnipeds for resting, molting, and reproduction. We examined terrestrial habitat preferences of four pinniped species (California sea lion, Guadalupe fur seal, harbor seal, and northern elephant seal) on the islands off the western coast of the Baja California Peninsula, Mexico. Boat-based surveys were conducted while circumnavigating 10 islands or archipelagos during summer and winter in 2009 and 2010. Habitat selection was inferred based on generalized linear models using animal counts and four habitat descriptors (substrate type, tide pools, bathymetry, and surf protection). The interspecific overlapping was analyzed using the Morisita index. Sea lions, fur seals, and harbor seals used sheltered beaches and rocky platforms as breeding sites. Cobblestone and sandy beaches were the most important substrates for elephant seals. Cliffs were the least preferred habitat by all species. Although substrate preferences were similar among species, segregation was observed in most islands except at the San Benito Archipelago, where sea lions co-inhabit with elephant seals and fur seals. In the context of a recolonization process, these results could provide insights about the location of future colonies and information on habitat use, which can be used when designing conservation strategies for the islands. [ABSTRACT FROM AUTHOR]

Predators have been considered to be good surrogates for measuring biodiversity, and raptors, in particular, have been proposed and used as biodiversity surrogates. This assumption is based on the general idea of concordance between two taxonomic groups that showed a similar spatial/temporal structure, with the aim of using one of the groups as a surrogate of the other. If a surrogate can be identified, then inferences can be made and conservation strategies can be established about the other. Assemblage concordance measures the degree of relationship between the composition patterns shown by two groups of organisms. In this study, we evaluated the effect of spatial and environmental variability on the degree of assemblage concordance between top-order predators (i.e. raptors), as the surrogate group, and vascular plants, reptiles, birds and mammals, as target groups. We also examined the potential causes of assemblage concordance and the degree to which the surrogate assemblage can predict community structure in the desert of southern Baja California Peninsula. Levels of assemblage concordance varied in all cross-taxon comparisons. We found that the concordance between raptors and birds may be due a combination of their similar responses to environmental gradients and trophic interactions, whereas other patterns of assemblage concordance are more likely derived from interactions between groups. We found low predictability and that no particular taxonomic group significantly predicted all the other groups. The low and shifting levels of assemblage concordance, in terms of environmental and spatial variables, suggest that raptors are poor biodiversity surrogates in this desert ecosystem. [ABSTRACT FROM AUTHOR]

Aim Previous work on the tidepool copepod Tigriopus californicus revealed a curious case of incipient speciation at the southern end of the species' range in Baja California, Mexico. The present study expands on the geography of this pattern and tests for congruence between reproductive and phylogenetic patterns. Location The Pacific coast of North America, from central Baja California to south-eastern Alaska (27-57° N), including the full range of T. californicus. Methods Primary techniques included mating experiments (> 4000 crosses), phylogeny reconstruction (mitochondrial cytochrome c oxidase subunit I) and screening of single nucleotide polymorphisms ( SNPs, 42 loci). Analyses used > 8000 copepods for the mating experiments, 86 copepods for the phylogeny and 41 copepods for the SNP assays. Phylogenies were constructed using Bayesian, maximum likelihood and maximum parsimony methods. Results Populations were found to fall into three reproductive groups: northern and southern groups that were reproductively isolated from each other, and an intermediate group that could serve as a conduit for gene flow. The northern and intermediate populations fell into one clade while all southern populations fell into a second clade. These two clades are now separated by less than 12 km at latitude 29.35° N. Nuclear SNP data for a subset of locations confirmed striking divergence between populations on either side of this boundary. The second (southern) clade was further subdivided into two clades separated by the lagoon region of Guerrero Negro (latitude 28° N). Main conclusions Reproductive assays and molecular data (both mitochondrial and nuclear) reveal a sharp break at 29.35° N, a region with no obvious barriers to dispersal, with no evidence for mixing across this narrow transition zone. Results also showed a milder break at the Guerrero Negro Lagoon (28° N), a location where breaks have been reported for other taxa. [ABSTRACT FROM AUTHOR]

Located in northwest Baja California, Mexico, the Guadalupe River Basin is situated in a semiarid region where periods of drought pose serious economic, social and environmental concerns. The study area has highly variable climate, with mean annual precipitation ranging from less than 12 mm to over 750 mm a year across the basin, and with most of the annual precipitation occurring during the autumn and winter seasons. To quantify the frequency and severity of meteorological droughts at the local (watershed) scale, this study investigates seasonal and annual precipitation data from 34 sites in northwest Baja California. Along with the analysis of precipitation climatology and interannual variability, El Niño/Southern Oscillation (ENSO) and related Pacific Ocean sea surface temperature (SST) patterns are shown to be potential predictors of seasonal precipitation. Analysis of precipitation variability at seasonal and annual time scales is performed using the standardized precipitation index (SPI) methodology, and annual, seasonal, and ENSO-conditioned precipitation frequency analyses are executed using the regional L-moment algorithm. The SPI and regional rainfall drought frequency estimates developed in this study may be useful for monitoring meteorological droughts and could serve as critical components of a comprehensive drought management plan. Furthermore, the methods applied in this study may be transferred to other semi-arid locations to mitigate drought risk and, potentially, impacts of drier conditions in the 21st century. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Summary In response to an outbreak of Rocky Mountain spotted fever (RMSF) in Baja California in early 2009, dogs at two shelters in neighbouring Imperial County, California, were evaluated for ectoparasites. Brown dog ticks ( Rhipicephalus sanguineus), a recognized vector for RMSF, were found on 35 (30%) of 116 dogs but all ticks tested negative for Rickettsia rickettsii by PCR. [ABSTRACT FROM AUTHOR]

The interannual distribution of early life stages of Pacific hake Merluccius productus, within the southern part of the California Current (32–23° N) from 1951 to 2001, was examined to describe the relationship between spawning habitat and environmental conditions. Mean annual abundance was affected by different factors along the west coast of the Baja California Peninsula. In the northern areas (Ensenada and Punta Baja), reduced abundance of larvae coincided with the El Niño and a North Pacific Ocean climatic regime shift, but in the southern areas (San Ignacio to Bahía Magdalena), the drastic reductions suggested a fishery effect for large adults of the coastal migratory population, starting in 1966. Two spawning stocks, coastal and dwarf, were evident in comparisons of latitudinal differences in occurrence of early stages and differences in temperature preferences that seemed to break at Punta Eugenia. [ABSTRACT FROM AUTHOR]

In México, 63% of the mammalian carnivore species are considered threatened. Therefore, we performed a prioritization exercise to find sets of areas needed for the conservation of Mexican terrestrial carnivores. Using a grid of half-degree cells, we mapped the distribution of richness, endemic and threaten species. Then, we determine the efficiency of the natural protected areas in México for protecting carnivores. Finally, we define optimal sets of complementary cells needed to represent all species either one or five times, or to represent at least 10% of the geographic distribution range of each carnivore in México. We perform this analysis including or excluding the existing protected areas, or excluding the top 10% cells with highest human population density (HPD). Species richness was higher in south-eastern México, threatened species concentrate in the same region, and also in the Yucatan's Peninsula. The Baja California Peninsula and the central region of the Mexican Plateau is where lower richness and numbers of threatened species are found. There is only one endemic carnivore distributed in the central and southern portion of the Pacific Slope. Complementary analysis showed that sets of three, 16 and 71 cells are required to represent one time, five times or at least 10% of the total distribution range of all species. Sets of 35 cells are needed to complement the natural protected areas to achieve this last representation goal. Finally, if cells with highest HPD are excluded, sets of three, 14 and 71 cells are needed to achieve our three representation goals. Our results provide insight into the ability of different sites to contribute to the representation of carnivore diversity at the national scale, and indicate gaps in the existing protected area network. [ABSTRACT FROM AUTHOR]

Aim We studied the relationship between the size and isolation of islands and bat species richness in a near-shore archipelago to determine whether communities of vagile mammals conform to predictions of island biogeography theory. We compared patterns of species richness in two subarchipelagos to determine whether area per se or differences in habitat diversity explain variations in bat species richness. Location Islands in the Gulf of California and adjacent coastal habitats on the Baja California peninsula in northwest Mexico. Methods Presence–absence surveys for bats were conducted on 32 islands in the Gulf of California using acoustic and mist-net surveys. We sampled for bats in coastal habitats of four regions of the Baja peninsula to characterize the source pool of potential colonizing species. We fitted a semi-log model of species richness and multiple linear regression and used Akaike information criterion model selection to assess the possible influence of log10 area, isolation, and island group (two subarchipelagos) on the species richness of bats. We compared the species richness of bats on islands with greater vegetation densities in the southern gulf ( n = 20) with that on drier islands with less vegetation in the northern gulf ( n = 12) to investigate the relationship between habitat diversity and the species richness of bats. Results Twelve species of bats were detected on islands in the Gulf of California, and 15 species were detected in coastal habitats on the Baja peninsula. Bat species richness was related to both area and isolation of islands, and was higher in the southern subarchipelago, which has denser vegetation. Log10 area was positively related to bat species richness, which increased by one species for every 5.4-fold increase in island area. On average, richness declined by one species per 6.25 km increase in isolation from the Baja peninsula. Main conclusions Our results demonstrate that patterns of bat species richness in a near-shore archipelago are consistent with patterns predicted by the equilibrium theory of island biogeography. Despite their vagility, bats may be more sensitive to moderate levels of isolation than previously expected in near-shore archipelagos. Differences in vegetation and habitat xericity appear to be associated with richness of bat communities in this desert ecosystem. Although observed patterns of species richness were consistent with those predicted by the equilibrium theory, similar relationships between species richness and size and isolation of islands may arise from patch-use decision making by individuals (optimal foraging strategies). [ABSTRACT FROM AUTHOR]

The broad distribution of the Sceloporus magister species group (squamata: phrynosomatidae) throughout western North America provides an appropriate model for testing biogeographical hypotheses explaining the timing and origins of diversity across mainland deserts and the Baja California Peninsula. We inferred concordant phylogenetic trees describing the higher-level relationships within the magister group using 1.6 kb of mitochondrial DNA (mtDNA) and 1.7 kb of nuclear DNA data. These data provide strong support for the parallel divergence of lineages endemic to the Baja California Peninsula ( S. zosteromus and the orcutti complex) in the form of two sequential divergence events at the base of the magister group phylogeny. A relaxed phylogenetic analysis of the mtDNA data using one fossil and one biogeographical constraint provides a chronology of these divergence events and evidence that further diversification within the Baja California clades occurred simultaneously, although patterns of geographical variation and speciation between clades differ. We resolved four major phylogeographical clades within S. magister that (i) provide a novel phylogenetic placement of the Chihuahuan Desert populations sister to the Mojave Desert; (ii) illustrate a mixed history for the Colorado Plateau that includes Mojave and Sonoran Desert components; and (iii) identify an area of overlap between the Mojave and Sonoran Desert clades near Yuma, Arizona. Estimates of bidirectional migration rates among populations of S. magister using four nuclear loci support strong asymmetries in gene flow among the major mtDNA clades. Based on the nonexclusivity of mtDNA haplotypes, nuclear gene flow among populations and wide zones of phenotypic intergradation, S. magister appears to represent a single geographically variable and widespread species. [ABSTRACT FROM AUTHOR]

Electronically tagged juvenile Pacific bluefin, Thunnus orientalis, were released off Baja California in the summer of 2002. Time-series data were analyzed for 18 fish that provided a record of 380 ± 120 days (mean ± SD) of ambient water and peritoneal cavity temperatures at 120 s intervals. Geolocations of tagged fish were estimated based on light-based longitude and sea surface temperature-based latitude algorithms. The horizontal and vertical movement patterns of Pacific bluefin were examined in relation to oceanographic conditions and the occurrence of feeding events inferred from thermal fluctuations in the peritoneal cavity. In summer, fish were located primarily in the Southern California Bight and over the continental shelf of Baja California, where juvenile Pacific bluefin use the top of the water column, undertaking occasional, brief forays to depths below the thermocline. In autumn, bluefin migrated north to the waters off the Central California coast when thermal fronts form as the result of weakened equatorward wind stress. An examination of ambient and peritoneal temperatures revealed that bluefin tuna fed during this period along the frontal boundaries. In mid-winter, the bluefin returned to the Southern California Bight possibly because of strong downwelling and depletion of prey species off the Central California waters. The elevation of the mean peritoneal cavity temperature above the mean ambient water temperature increased as ambient water temperature decreased. The ability of juvenile bluefin tuna to maintain a thermal excess of 10°C occurred at ambient temperatures of 11–14°C when the fish were off the Central California coast. This suggests that the bluefin maintain peritoneal temperature by increasing heat conservation and possibly by increasing internal heat production when in cooler waters. For all of the Pacific bluefin tuna, there was a significant correlation between their mean nighttime depth and the visible disk area of the moon. [ABSTRACT FROM AUTHOR]

Geological forces and long-term climate changes can have profound effects on species. Such effects may be manifested in the pattern and magnitude of genealogical diversity, as revealed by mitochondrial DNA (mtDNA) lineages. The relative importance of the different forces on a regional biota must be evaluated along with a good understanding of geological and climatological history. The peninsula of Baja California of north-western Mexico is one area where both geology and climate have affected the historical biogeography of the regional biota. Molecular studies based on the genealogical relationships among mtDNA lineages have contributed greatly towards elucidating the historical biogeography of Baja California. Perhaps most noticeably, numerous concordant breaks in mtDNA genealogies half-way along the peninsula suggest a vicariant history in which the mid-peninsula was temporarily submerged. This vicariant explanation has recently been criticized, as no conclusive geological evidence exists for a continuous submergence of the mid-peninsula. As an alternative, a scenario based on climatological factors has been suggested. Here we discuss the validity of the hypothesized mid-peninsular vicariance event and the climate-based alternative in explaining the concordant genealogical breaks. We argue that, despite the significant changes in climate brought about by the glacial cycles throughout the Quaternary, a vicariant history involving a mid-peninsular seaway remains the most parsimonious explanation of the observed patterns in mtDNA genealogies. [ABSTRACT FROM AUTHOR]

Aim Native American fire use influenced bark thickness of coastal and island Monterey pine ( Pinus radiata D. Don) and bishop pine ( Pinus muricata D. Don) populations. Methods Basal bark thickness and d.b.h. were measured in two common-garden pine plantations that included all five native Monterey pine populations and nine of 10 native bishop pine populations. One-factor analysis of covariance was used to determine if significant differences in bark thickness existed between island and coastal populations. Results Bark thickness was measured on 228 Monterey and 42 bishop pines. Bark thickness in coastal and island Monterey pine populations was significantly different. Bark thickness in coastal and island bishop pine populations was not significantly different. Main conclusions Basal bark was thick in populations where there was a history of Native American burning. Basal bark was thin in two island populations where Native Americans have been absent or distant from the pine populations. While other influences no doubt affect the evolution of lower-bole bark thickness, it appears that frequent anthropogenic fires may be a powerful selection force. [ABSTRACT FROM AUTHOR]

Question: What are the shape, abundance, size, and structural characteristics of sapling patches in an old-growth Pinus jeffreyi-mixed conifer forest with a relatively intact disturbance regime? Location: Sierra San Pedro Martir, Baja California, Mexico. Methods: Regeneration was quantified by sampling sapling patches on seven 1200 m permanently marked line transects. For all patches intersected, tree size, species, age, and patch canopy cover were recorded. Patch structural characteristics were statistically compared to data from unbiased forest inventory plots. The minimum regeneration patch was defined as three saplings in a 49-m² area. Results: We sampled 54 sapling regeneration patches. Patch size varied from 6.6 to 674.8 m². A small portion of the forest was in patches (patch fraction = 3.8%, patch abundance = 8.5 per ha). The majority of the patches were small; 64.8% were less than the mean patch area of 100.1 m². Patches were shaped as a rhombus. For all forest characteristics, mean values inside patches were significantly different than those from the unbiased forest inventory plots. Conclusions: These forests have a fine-grained pattern of regeneration patches. Our largest patch size of 674.8 m² is the smallest reported in Pinus jeffreyi, P. ponderosa, and mixed conifer forests; other studies have probably had more difficulty delineating regeneration patches because of forest ingrowth from fire exclusion. Frequent fire, irregular seed crops, and seed dispersal by small mammals and birds could create this regeneration patch regime. High variation in nutrient availability after fire could also contribute to increased stand patchiness. [ABSTRACT FROM AUTHOR]

The subsurface geometry of the Sebastián Vizcaíno Basin is obtained from the 2D inversion of gravity data, constrained by a density-versus-depth relationship derived from an oil exploration deep hole. The basin accumulated a thick pile of marine sediments that evolved in the fore-arc region of the compressive margin prevalent along western North America during Mesozoic and Tertiary times. Our interpretation indicates that the sedimentary infill in the Sebastián Vizcaíno Basin reaches a maximum thickness of about 4 km at the centre of a relatively symmetric basin. At the location of the Suaro-1 hole, the depth to the basement derived from this work agrees with the drilled interface between calcareous and volcaniclastic members of the Alisitos Formation. A sensitivity analysis strongly suggests that the assumed density function leads to a nearly unique solution of the inverse problem. [ABSTRACT FROM AUTHOR]

The Baja California region provides a natural setting for studying the early mechanisms of allopatric speciation in marine systems. Disjunct fish populations from several species that occur in the northern Gulf of California and northern Pacific coast of Baja California, but are absent from its southern shores, were previously shown to be genetically isolated, making them excellent candidates for studying allopatry. In addition, one of these species, the sargo Anisotremus davidsonii, has two pairs of congeneric Panamic trans-isthmian geminate species that allow for internal molecular clock calibration. Phylogeographic and demographic approaches based on mitochondrial (cytochrome b) and nuclear (S7 ribosomal protein) sequences showed that A. davidsonii entered the gulf from the south, and later colonized the Pacific coast, approximately 0.6–0.16 million years ago. Pacific coast colonization may have used a route either around the southern cape of Baja California or across the peninsula through a natural seaway. However, while several seaways have been described from different geological times, none matches the dates of population disjunction, yet much geological work remains to be done in that area. At the present time, there is no evidence for dispersal around the southern tip of the Baja California Peninsula. Signatures of incipient allopatric speciation were observed, such as the reciprocal monophyly of disjunct populations for the mitochondrial marker. However, other characteristics were lacking, such as a strong difference in divergence and coalescence times. Taken together, these results suggest that disjunct populations of A. davidsonii may be consistent with the earliest stages of allopatric speciation. [ABSTRACT FROM AUTHOR]

We investigate the controls on the architecture of coarse-grained delta progradational units (PUs) in the Pliocene Loreto basin (Baja California Sur, Mexico), a half-graben located on the western margin of the Gulf of California. Dorsey et al. (1997b) argued that delta progradation and transgression cycles in the basin were driven by episodic fault-controlled subsidence along the basin-bounding Loreto fault. Here we test this hypothesis by a detailed analysis of the sedimentary architecture of 11 exceptionally well-exposed, vertically arranged fluvio-deltaic PUs, each of which shows lateral facies transition from proximal alluvial facies palaeo-seaward into distal pro-delta facies. Of these 11 PUs, seven exhibit a lateral transition from a shoal water to Gilbert-delta facies associations as they are traced palaeo-seaward. This transition is characterised by down-transport development of foresets, which grow in height up to 35 m. Foreset units thicken in a basinward direction, with initially an oblique topset–foreset geometry that becomes increasingly sigmoidal. Each delta is capped by a shell bed that records drowning of the delta top. This systematic transition in delta architecture records increasing water depth through time during individual episodes of progradation. A mechanism that explains this transition is an accelerating rate of fault-controlled subsidence during each PU. During episodes of low slip rate, shoal-water deltas prograde across the submerged topography of the underlying delta unit. As displacement rate accelerates, increasing bathymetry at the delta front leads to steepening of foresets and initiation of Gilbert deltas. Subsequent delta drowning results from sediment starvation at the shoreline at high slip rates because of sediment trapping upstream. The observed delta architecture suggests that the long-term (>100 kyr) history of slip on the Loreto fault was characterised by repetitive episodes of accelerating displacement accumulation. Such episodic fault behaviour is most likely to be because of variations in temporal and spatial strain partitioning between the Loreto fault and other faults in the Gulf of California. A physical explanation for the acceleration phenomenon involves evolving frictional properties on the episodically active Loreto fault. [ABSTRACT FROM AUTHOR]

The Baja California peninsula represents a biogeographical boundary contributing to regional differentiation among populations of marine animals. We investigated the genetic characteristics of perennial and annual populations of the marine angiosperm,Zostera marina,along the Pacific coast of Baja California and in the Gulf of California, respectively. Populations ofZ.marinafrom five coastal lagoons along the Pacific coast and four sites in the Gulf of California were studied using nine microsatellite loci. Analyses of variance revealed significant interregional differentiation, but no subregional differentiation. Significant spatial differentiation, assessed usingθST values, was observed among all populations within the two regions.Z. marinapopulations along the Pacific coast are separated by more than 220 km and had the greatestθST (0.13–0.28) values, suggesting restricted gene flow. In contrast, lower but still significant genetic differentiation was observed among populations within the Gulf of California (θST = 0.04–0.18), even though populations are separated by more than 250 km. This suggests higher levels of gene flow among Gulf of California populations relative to Pacific coast populations. Direction of gene flow was predominantly southward among Pacific coast populations, whereas no dominant polarity in the Gulf of California populations was observed. The test for isolation by distance (IBD) showed a significant correlation between genetic and geographical distances in Gulf of California populations, but not in Pacific coast populations, perhaps because of shifts in currents during El Niño Southern Oscillation (ENSO) events along the Pacific coast. [ABSTRACT FROM AUTHOR]

Phylogenetic analyses of complete mitochondrial cytochrome b sequences support the monophyly of pocket gopher ( Thomomys bottae) populations from the 1000 km length of the Baja California peninsula of Mexico, relative to other geographical segments of the species range in western North America. The Baja California peninsula is an area that encompasses considerable ecomorphological and infraspecific diversity within this pocket gopher species. However, detailed population analyses encompassing 35 localities distributed over the southern half of the peninsula reveal only trivial phylogeographical structure. Rather, most of the 72 unique 500-base pair haplotypes examined from 142 individuals is restricted to single populations, although a few haplotypes are shared broadly across geography. Individual populations are typically comprised of haplotype sets from different branches in a network of relationships. Analysis of molecular variance ( amova) indicates that approximately half of the total pool of variation is contained among individuals within local populations, and that only about 25% can be explained by the regional subdivisions of current subspecies distributions or physiographic realms. A hypothesized historical vicariant event that has been causally linked to the phylogeographical structure of other, codistributed species has had little influence on these pocket gopher populations, explaining only 13% of the total variation. The temporal depth, estimated by coalescence parameters, of the haplotype lineage in Baja California is relatively recent, approximately 300 000 generations; both the mismatch distribution of pairwise comparisons and a significantly positive exponential growth estimate support a recent history of expanding populations; but current, or recent past, migration estimates have remained small, are largely unidirectional from north to south, and weak isolation by distance is present. All data suggest that pocket gophers have relatively recently invaded the southern half of peninsular Baja California, with the genetic signature of expansion still evident but with sufficient time having lapsed to result in a weak isolation by distance pattern. The geographical assemblage of sampled populations thus appears as a meta-population, with limited gene flow contrasting with random haplotype loss due to drift in small, localized populations. [ABSTRACT FROM AUTHOR]

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Abstract Aim To analyse the distributional patterns of the Baja California Peninsula's resident avifauna, and to generate a regionalization based on a method that uses a parsimony analysis (parsimony analysis of endemicity, PAE) of point data and modelled potential distributions. Location The Baja California Peninsula, Mexico. Methods A data base was constructed containing records of 113 species of resident terrestrial birds present in the Baja California Peninsula. Records and localities were obtained from the literature and from specimens housed in scientific collections world-wide. Raw data points and potential distribution maps obtained using the software Genetic Algorithms for Rule-set Prediction (GARP), were analysed with PAE. Results The data base consisted of 4164 unique records (only one combination of species/locality) belonging to 113 terrestrial resident bird species, in a total of 809 localities. From the point distribution matrix, the analysis generated 500 equally parsimonious trees, from which a strict consensus cladogram with 967 steps was obtained. The cladogram shows a basal polytomy and some geographical correspondence of a few resolved groups obtained in the analysis. These results do not allow the recognition of areas defined by avifaunistic associations. From the potential distribution matrix, the analysis generated 501 equally parsimonious trees, and a strict consensus cladogram of 516 steps was obtained. The cladogram shows a higher resolution because of the number of resolved groups with better geographical correspondence and therefore regions are well-defined. Main conclusions The correspondence of some groupings of species suggest their validity as areas with biogeographical (historical and/or ecological) meaning. This regionalization in the Baja California avifauna seems to be consistent with previous regionalizations for other groups. Hence, PAE is a useful tool for area categorization if reliable point records and prediction tools... [ABSTRACT FROM AUTHOR]

Unattached, nongeniculate, coralline algae or rhodoliths exhibit a range of morphological variability seemingly dependent on environmental factors. Rhodoliths have an extensive fossil record, and environmentally dependent characteristics make them potentially reliable paleoindicators. Species of the rhodolith-forming genus Lithophyllum Philippi in Baja California Sur, Mexico were recently consolidated into one species. Under the new classification, L. margaritae (Hariot) Heydrich consists of several growth forms presumably reflecting local environmental conditions. We examined the genetic structure of four populations of this species using amplified fragment length polymorphisms (AFLP) to characterize the extent of genetic variation associated with foliose and fruticose growth forms. AFLP band sharing analysis revealed that foliose growth forms exhibited consistently higher intrapopulation similarities (0.75–0.85) than fruticose growth forms (similarity range, 0.55–0.67). This trend was also evident in comparisons of geographically isolated populations. These data indicate that the two morphologies are genetically distinct and that genetic exchange between foliose and fruticose growth forms of L. margaritae may be limited. Consequently, rhodolith growth forms appear to be the result of an interplay between both genetic makeup and environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract Aims Ants (Hymenoptera: Formicidae) of the Baja California peninsula are poorly known, with information based largely on scattered museum and literature records. We provide the first comprehensive account of ant species occurring on the peninsula, we examine distribution patterns, and we assess the ‘peninsular effect’ which predicts that species richness declines from the base to the tip of a peninsula. Location Peninsula of Baja California, Mexico. Methods Data collection involved examining, identifying and recording label data from c. 2350 series of ants. These records provide a provisional, if incomplete, species list. We applied the incidence-based estimator, Chao-2, to our data base of specimen records to estimate the total number of ant species on the peninsula. We assessed endemism by comparing our peninsular species list to those from adjacent states. The peninsular effect was tested by comparing genus and species level richness between the two states of Baja California, and across five latitudinal blocks. Results We document 170 native ant species in thirty-three genera, plus six non-native species, in Baja California. It seems likely that additional species remain to be discovered: the Chao-2 estimator of species richness, at 206.0 species, is about 20% higher than our observed species richness. About 30% of the species and 20% of the genera are restricted within Baja California to the relatively mesic California Floristic Province of north-western Baja California. Nearly all of these species also occur in California. Forty-seven species (27.6%) are peninsula endemics. Using our entire data set, the peninsular effect appears to be strong, with about twice as many species in the northern state of Baja California than are recorded from the southern state of Baja California Sur; the ratio of genera is 33 to 24. However, this effect becomes weak at the species level and absent at the genus level when minimizing habitat effects by... [ABSTRACT FROM AUTHOR]

Presents information on a study which traced the thermal evolution of the Monte Blanco dome in the Sierra El Mayor of northeastern Baja California. Geologic and tectonic setting; Sampling and analytical methods; Thermal history results; Conclusions.

The Pliocene Loreto basin is an asymmetrical half graben located on the eastern margin of Baja California Sur, Mexico, which formed by rapid subsidence along the dextral-normal Loreto fault. The southern Loreto basin contains numerous, well exposed coarse-grained Gilbert-type fan deltas that were derived from the footwall of the Loreto fault. Detailed sedimentological study of individual foreset beds provides information about down-slope flow transformations of cohesionless sediment gravity flows in shallow water. Deposits of Gilbert-delta foresets consist of ungraded, normal-graded, inverse- to normal-graded, and bipartite conglomerate and sandstone. Lateral transitions in sorting, grading style and internal structure are commonly observed within individual beds, both across and down slope, suggesting heterogeneity within flows and a close relationship between high-density turbidity currents and gravel traction carpets. A conceptual model for flow transformation and deposition of high-density turbidity currents on Gilbert-delta foreset slopes is developed for Pliocene strata in the Loreto basin. In this model, ungraded cohesionless debris flows evolved rapidly down-slope into normal-graded gravelly turbidity currents. With continued down-slope transport, the gravel fraction collapses and becomes concentrated into a basal traction carpet undergoing laminar shear, and is over-ridden by a sandy turbulent suspension. The short distances (10–20 m) over which lateral transitions within single beds are observed indicate very rapid flow transformations (10–20 s) and rapid deposition of gravel traction carpets by frictional freezing on and near the base of the foreset slope. [ABSTRACT FROM AUTHOR]

In terms of biomass, Sargassum lapazeanum (Phaeophyceae, Fucales) is one of the most important seaweeds in La Paz Bay, on the southeastern coast of the Baja California Peninsula, Mexico. This species can be found year-round in shallow subtidal sites. Standing biomass is lowest between fall and winter and highest between spring and summer. We are currently studying the annual demography of fronds as a necessary step to understanding the mechanisms of population regulation. Work is being done on a bed of about 90 m in length and three m in width. At this stage of abstract submission, we can report results for winter only. Random samples were collected in February and in March 2000 to estimate stand biomass, frond density, and size (frond length) structure. In addition, we labeled fronds with numbered plastic tags to estimate their rates of growth and of mortality during this period. Rates of recruitment were estimated from a combined analysis of the above. In February, fronds were all shorter than 6.5 cm. Between February and March, mean total frond density increased from 122 to 776 fronds m−2 (n = 30 quadrats). The mean recruitment rate was 667 fronds m−2, the mean growth rate was 0.5 cm day−1 (n = 60 fronds), and the mean mortality rate was 43 fronds m−2. From last year's preliminary observations, we expect to observe peaks of biomass and of reproduction in late spring, followed by negative growth rates and high mortality rates during summer. [ABSTRACT FROM AUTHOR]

Two abalone species: green Haliotis fulgens and yellow Halioti corrugata represent nearly 97% of the total production in the Mexican abalone fishery. It has been assumed that abalone feed on the kelp algae Macrocystis pyrifera. Regional hatcheries use this species as a main source of natural food. M. pyrifera does not occur at the southern limit of the distribution of abalone species along the Baja California Peninsula. In this study, growth rates of juveniles H. fulgens, 17.3 ± 2.2 mm shell length and 0.4 ± 0.2 g body weight, were evaluated. Juveniles were fed with common species in the benthic environments inhabited by abalone along the western coast of Baja California during 191 days. Three diets were based on algae: palm kelp, Eisenia arborea, giant kelp, M. pyrifera and Gelidium robustum, and one on seagrass, Phyllospadix torreyi. Shell length and body growth rates varied between 21.5 μm day−1 and 2.2 mg day−1 for E. arborea and between 45.9 μm day−1 and 6.7 mg day−1 for M. pyrifera. Higher specific growth rates (SGR) in length and weight were determined for M. pyrifera: 0.2% and 0.7% day−1. Significant differences between values of juveniles fed M. pyrifera with the rest of the diets were found. The highest mortality (21%) was in juveniles fed the red algae G. robustum. [ABSTRACT FROM AUTHOR]

Porphyra perforata is a common species off the Pacific coast of Baja California peninsula. In situ growth, phenology and reproductive characteristic of this plant are being determined in order to evaluate the feasibility of its culture in open water conditions. Contrary to previous studies that describe this species as ephymeral, P. perforata is present all year around off the north coast of the Baja California peninsula. Its vertical distribution is limited to a band, +50 to +150 cm above sea level. However, subtidal growth transplant experiments showed that the plants are capable of growing down to a depth of 5 m. Highest growth rates were observed from February to July, then tissue was lost as a consequence of sexual reproduction. Biomass continues to decreases for the rest of the year. About 50% of the plants were reproductive by May and more than 90% by August. Oysters shells were introduced and collected every month to evaluate the presence of chonchocelis phase and P. perforata recruitment. Chonchocelis was observed all year and new recruits were present from September to February. These results suggest that the foliar phase P. perforata could be cultured in the ocean for about six months of the year and could be culture subtidally. [ABSTRACT FROM AUTHOR]