Box-shaped halophilic bacteria

Three morphologically similar strains of halophilic, box-shaped procaryotes have been isolated from brines collected in the Sinai, Baja California (Mexico), and southern California (United States). Although the isolates in their morphology resemble Walsby's square bacteria, which are a dominant morphological type in the Red Sea and Baja California brines, they are probably not identical to them. The cells show the general characteristics of extreme halophiles and archaebacteria. They contain pigments similar to bacteriorhodopsin which apparently mediate light-driven ion translocation and photophosphorylation.     

Genetic diversity and population structure of North America’s rarest heron, the reddish egret (Egretta rufescens)

The global distribution of the reddish egret is characterized by disjunct colonies occurring from the Pacific side of Northwest Mexico to the Caribbean. We examined distantly isolated colonies of reddish egret to determine global population genetic structure. We used seven polymorphic microsatellites to accomplish five goals: (1) to assess range wide population differentiation among reddish egret (Egretta rufescens) populations, (2) identify extent of gene flow, (3) determine any historical occurrence of bottlenecks, (4) assess genetic differentiation between color morphs, (5) clarify subspecies status of E. r. dickeyi, a completely dark morph population located in and around the Baja California peninsula, Mexico. Genetic differentiation was dramatic (global Fst = 0.161) throughout the reddish egrets range extending from Baja California, Mexico to Great Inagua, Bahamas. Differentiation occurred among three distinct regions (Fst = 0.238) but not among colonies/islands within regions suggesting regional philopatry. Genetic diversity (alleles per locus, and heterozygosity) in Baja California Sur, Mexico and Great Inagua, Bahamas populations is lower than in the Texas/Mexico population due to minimal dispersal between regions and smaller population sizes. Dark and white color morphs when present within the same region showed no differentiation. Patterns of recent population bottlenecks are not evident in each of the three regional populations. With evidence of limited gene flow in addition to low genetic diversity and prospects of habitat loss we recommend that reddish egrets be managed as three distinct or evolutionary significant units.     

New records of large branchiopods (Branchiopoda: Anostraca,Notostraca, and Spinicaudata) in Mexico

This paper reports new distribution records of large branchiopods for Mexico following a three year survey of the Baja California peninsula. The occurance of the anostracans Thamnocephalus mexicanus (Linder, 1941) and T. platyurus (Packard, 1877), the notostracan Lepidurus lemmoni (Holmes, 1894), and the spinicaudatans Eulimnadia cylindrova (Belk, 1989) and E. texana (Packard,1871), all represent the first records for the peninsula. An undescribed species of the anostracan genus Streptocephalus is recorded from the state of Baja California (Norte). The occurrence of the notostracan genus Triops and four other anostracan species on the peninsula is also confirmed. The conchostracan Cyclestheria hislopi (Baird, 1859) is recorded from the state of Quintana Roo. The collections of Lepidurus and Cyclestheria are the first records for México. These records increase the number of species of large branchiopods reported fromMéxico to 36: 20 Anostraca, 3 Notostraca, 11 Spinicaudata, and 2Laevicaudata. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Revision of the genus Wislizenia (Capparidaceae) based on population studies

Morphological and cytological studies of mass collections from the southwestern United States and Baja California, and morphological studies on herbarium specimens from these areas and northern Mexico have been used to solve a taxonomic problem within the genusWislizenia. Canonical analysis of morphological data from mass collections separates three geographic groups from: California, Baja California, and states east of California. A similar analysis of herbarium specimens collected throughout the range ofWislizenia refracta confirms the reality of these groups, for which the status of subspecies is proposed: 1) subsp.californica from the California central valley, 2) subsp.palmeri from Baja California and the Sonoran coast, and 3 ) subsp.refracta from states east of California. This taxonomic treatment differs from any of the varied previous ones. Chromosome numbers for six of the mass collections were found to ben = 20, in agreement with other reports.     

The role of anthropogenic influences in a mixed-conifer forest mortality episode

Abstract. Anthropogenic influences on recent tree mortality in mid-montane mixed conifer forests of southern California, USA, and northern Baja California, Mexico, were investigated. The Pinus jeffreyi-Abies concolor phase of the mixed-conifer montane community was sampled at three sites, characterized by: (1) low levels of air pollution and long-term fire suppression (Holcomb Valley in the San Bernardino Mountains, California); (2) chronic, severe air pollution and long-term fire suppression (Barton Flats in the San Bernardino Mountains, California); and (3) little air pollution and no fire suppression (La Corona Arriba in the Sierra San Pedro Martir in Baja California, Mexico). Similar percentages of dead standing trees, around 14 %, were found at both San Bernardino sites, but a comparatively low level, 4 %, was found in the Mexican forest. Anthropogenic effects, in particular fire suppression, may play an important role in enhancing the impact of natural stresses on the dynamics of mixed conifer forests.     

A taxonomic revision of the New World genus Oropodes Casey (Coleoptera, Staphylinidae, Pselaphinae)

The genus Oropodes is characterized and revised with 18 species being treated. Members of this genus are found in temperate forests to desert brush lands from Oregon to Baja California, but are associated primarily with dry forests and shrub lands of California. Keys to males and females, where known, are provided. Seven species are redescribed: Oropodes arcaps (California), Oropodes dybasi (Oregon), Oropodes ishii (California), Oropodes nuclere (California), Oropodes orbiceps (California), Oropodes rumseyensis (California), Oropodes yollabolly (California). The name Oropodes raffrayi (California) is raised from synonymy and the species is redescribed, NEW STATUS. Ten new species are described: Oropodes aalbui (California), Oropodes bellorum (California), Oropodes casson (California), Oropodes chumash (California), Oropodes esselen (California), Oropodes hardyi (California), Oropodes serrano (California), Oropodes tataviam (California), Oropodes tongva (California), and Oropodes tipai (Baja California, Mexico), NEW SPECIES. These species are placed into three species groups: the arcaps-group, the orbiceps-group, and the raffrayi-group. Data for a new record of Euplecterga fideli are given, and a list of the unassociated Oropodes females with distinctive genitalia is included with their label data.     

Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: afirst overview

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 omitting species restricted to the California Floristic Province. At a finer scale, across latitudinal blocks of about 1.9°, the number of species declines towards central portions of the peninsula and then increases in the Cape Region. Nine ant species display strongly disjunct distributions, and these occur in two general patterns: peninsula disjuncts and peninsula–mainland disjuncts. Main conclusions The Baja California peninsula supports a diverse and distinctive ant fauna, with the proportion of endemic species similar to that displayed by plants. Patterns of species and genus richness across the five latitudinal blocks provide poor support for the peninsular effect. Moreover, habitat diversity, especially that related to topographic relief, appears to be the most important factor affecting the gradient of ant species richness in Baja California. Additional collections are needed to develop a more complete species list and to determine the boundaries and status of many species. Nevertheless, the present data base provides a useful starting point for understanding the evolution of ant assemblages in Baja California and for comparison with peninsular patterns in other taxa.     

Integral state on the Northern Border of Mexico: administration and surveillance of subaltern groups in Tijuana,Baja California

Dialectical Anthropology - The article examines the correlation of forces between the government apparatus and civil society in the municipality of Tijuana (Baja California, Mexico). Through a...     

Use of Museum Specimens to Refine Historical Pronghorn Subspecies Boundaries

Endangered Sonoran (Antilocapra americana sonoriensis) and Peninsular (A. a. peninsularis) pronghorn persist largely because of captive breeding and reintroduction efforts. Recovery team managers want to re-establish pronghorn in their native range, but there is currently uncertainty regarding the subspecies status of extinct pronghorn populations that historically inhabited southern California, USA, and northern Baja California, Mexico. To address this uncertainty, we genotyped museum specimens and conducted phylogenetic and population genetic analyses of historical data in the context of 3 contemporary pronghorn populations. The historical northern Baja California pronghorn share the most ancestry with contemporary Peninsular pronghorn, whereas pronghorn in southern California share more ancestry with contemporary American (A. a. americana) pronghorn. For reintroductions into northern Baja California, the Peninsular subspecies is more appropriate based on museum genetic data. For reintroductions into Southern California, ecological and genetic factors are both important, as the subspecies most genetically related to historical populations (American) may not be well-adapted to the hot, low-elevation deserts of the reintroduction area. © 2019 The Wildlife Society.     

Louse flies on birds of Baja California

Louse flies were collected from 401 birds of 32 species captured in autumn of 1996 in Baja California Sur (Mexico). Only one louse fly species (Microlynchia pusilla) was found. It occurred in four of the 164 common ground doves (Columbina passerina) collected. This is a new a host species for this louse fly.     

Paleoislands in the stream: paleogeography and expected circulation patterns

Marine islands belong to discrete geographic realms attended by persistent patterns of oceanic and atmospheric circulation. Wet and dry vegetation zones on the opposite sides of Hawaii, for example, result from northeasterly trade winds in an open-ocean setting. Distinct windward and leeward shores are due to variations in wave exposure. The Channel Islands off southern California meet northwesterly winds that push the California Current and its associated upwelling along the west coast of North America. Other islands within the Gulf of California are influenced by the seasonal shifts in winter and summer winds related to a semi-monsoonal pattern of atmospheric circulation. Ancient islands preserved in the rock record as drowned monadnocks provide a direct link to a comparable range of climatic and oceanographic interactions through Phanerozoic time. Exemplary case studies, one each from the Paleozoic, Mesozoic, and Cenozoic eras, are reviewed with respect to geography, ecology, and climate. They include the Ordovician Jens Munk Archipelago on Hudson Bay in Manitoba (Canada), the Cretaceous island group on the Pacific shores of northern Baja California (Mexico), and the Pliocene Santa Inès Archipelago from the Gulf of California in Baja California Sur (Mexico). Key physical features shared in common include sedimentary ramps with 6–12° slopes constructed on basal conglomerates that incorporate debris from eroded basement rocks. Biological attributes shared in common are contrasting biofacies indicative of distinct windward and leeward environments.     

Ecological aspects of Sargassum muticum (Fucales,Phaeophyta) in Baja California,Mexico: reproductive phenology and epiphytes

The reproductive phenology and epiphytic macroalgae of Sargassum muticum were studied through an annual cycle (September 1987 to November 1988) at two sites on the northwestern coast of Baja California, Mexico, which were subjected to different degrees of wave exposure. Sargassum muticum is a brown alga of Japanese origin, now considered a permanent member of the marine flora of Baja California. A similar reproductive development was observed at both sites, with a maximum percentage of reproductive plants from May to July (spring–summer) and minimum from December to March (winter). Reproductive plants were found throughout the year. A total of 48 species of epiphytes were identified and seasonal variation in their diversity was observed. The greatest diversity was found at the more protected site.     

THE DISTRIBUTION AND ABUNDANCE OF DEEPWATER MACROALGAE IN CENTRAL CALIFORNIA

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis , to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa , which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis , but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.     

Bacterial and archaeal profiling of hypersaline microbial mats and endoevaporites,under natural conditions and methanogenic microcosm experiments

Extremophiles - Bacterial and archaeal community structure of five microbial communities, developing at different salinities in Baja California Sur, Mexico, were characterized by 16S rRNA...     

Structure of Benthic Diatom Assemblages from a Mangrove Environment in a Mexican Subtropical Lagoon1

The taxonomic list and the structure of benthic diatom assemblages occurring in fine sediments (silt and sand) from the mangrove forest of the Balandra lagoon in Baja California Sur, Mexico was determined based on seasonal samplings for one year. Assemblage structure was analyzed using several ecological indices for estimating diversity (H'), dominance (REDI), equitability, and similarity. A total of 230 diatom taxa were identified and include 109 new records for the Baja California peninsula coast. Taxa representative of highly productive and hypersaline environments were common. Assemblages were characterized by a few abundant species and many uncommon or rare taxa. High diatom diversity estimates at all sampling sites during all seasons suggest that diatom assemblages in sediments of the Balandra lagoon represent a quasi-pristine environment.     

SPATIAL AND SEASONAL DISTRIBUTION OF THE HUMPBACK WHALE, MEGAPTERA NOVAEANGLIAE, IN THE MEXICAN PACIFIC

From observations of the spatial distribution of humpback whales in the Mexican Pacific between 1981 and 1986, it is possible to recognize four subregions: 1) the southern coast of Baja California; 2) the northern Gulf of California, including the Midriff Islands; 3) the mainland coast of Mexico, including the Isla Isabel and Islas Tres Marias and 4) the Revillagigedo Archipelago. The seasonal distribution of whales near the Mexican mainland and the Revillagigedo Archipelago extends from November to May and is similar to that of other winter breeding grounds, including the Hawaiian Islands. Along the southern coast of Baja California, whales have been observed from September to April, possibly indicating a shorter migratory route. In the northern Gulf of California, however, humpback whales have been reported throughout the year and are occasionally observed feeding during both summer and winter months. The degree of individual movement between the four subregions is still unknown. The number of individual humpback whales identified photographically in recent years suggests that there ate more whales in the Mexican Pacific than previously reported.     

Sesquiterpene lactones from dicoria canescens

Dicoria canescens from Baja California, Mexico afforded the known monoterpene glucoside, (?)-cis-chrysanthenol O-β-d-glucopyranoside, ivalbatin, a xanthanolide and two new sesquiterpene lactones, 4-dihydroivalbatin (dicorin) and 11β, 13-tetrahydrovalbatin (dihydrocorin).     

HYDROCARBONS FROM PEDILANTHUS MACROCARPUS (EUPHORBIACEAE) OF BAJA CALIFORNIA AND SONORA,MEXICO

Pedilanthus macrocarpus (Euphorbiaceae) from Baja California and Sonora, Mexico is a desert xerophyte rich in polyisoprenes and other highly reduced hydrocarbons. The latex was analyzed for rubber content and found to contain 6–10% rubber by fresh weight. Four geographically distinct populations were analyzed for alkane content and the normal alkane range was shown to be C₂₇H₃₆ to C₃₅H₇₂. The different populations show significant quantitative and qualitative variation in their alkane content. Phytochemical findings suggest that the hydrocarbon chemistry can be useful in understanding the evolution of Pedilanthus macrocarpus in Baja California.     

GEOGRAPHICAL CORRELATION OF MORPHOLOGICAL VARIATION IN SILVETIA COMPRESSA (FUCACEAE,FUCALES, PHAEOPHYCEAE)

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis, to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa, which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis, but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.     

The invasive bullfrog <Emphasis Type="Italic">Lithobates catesbeianus</Emphasis> in oases of Baja California Sur,Mexico: potential effects in a fragile ecosystem

The American bullfrog (Lithobates catesbeianus), considered as one of the world’s worst invasive species because of its negative effects on native fauna, has been introduced into over 40 countries in four continents. The invasion status in Mexico is poorly known. The first known record for this species in the Peninsula of Baja California, northwestern Mexico is an individual collected 35 years ago. A great portion of the peninsula is an arid desert where the sources of freshwater are the spring-fed oasis and mountain arroyos that support rare and endemic species closely associated with wetland conditions. Humans, who have introduced alien species, inhabit many of those oases. The aim of this work was to document the presence of the exotic bullfrog in 40 oases and mountain arroyos in Baja California Sur state during 2006–2009. Bullfrogs were found in 25% of the oases sampled; 15% have confirmed records of breeding populations and five oases are new location records. Our results show a considerable increase (50%) in the number of oasis invaded by bullfrogs in only 8 years. The animal populations of rare or endemic species associated with oases would be threatened by the arrival of bullfrogs. Actions for their control and eradication are urgently needed.