Variation in DNA microsatellites of the ferruginous pygmy-owl (Glaucidium brasilianum)

Eleven polymorphic microsatellite loci were used to assess genetic variation in the ferruginous pygmy owl (Glaucidium brasilianum) from North America. Analysis of genotypic variation suggests restricted gene flow between pygmy-owl populations in Arizona-Sonora and Sinaloa, and Texas and the remaining states in Mexico. The Arizona-Sonora population showed signs of a recent genetic bottleneck, an observation supported by low population estimates for Arizona (13–117 individuals). Heterozygosity in Arizona, however, was equal to levels recorded throughout Mexico and Texas. Congruent patterns revealed by nuclear (microsatellites) and mitochondrial DNA that indicate Arizona-Sonora and Texas populations are distinct from adjacent populations in Mexico, thus emphasizing need for the design and implementation of separate management plans for recovery and conservation efforts. Revealing evidence of distinct groups within the pygmy-owl populations in North America, results from this study may be used to make management decisions for the recovery and conservation of this species.     

Thermosphaeroma subequalum,n. gen., n. sp. (crustacea: Isopoda) from Big Bend National Park,Texas

A new species of the Sphaeromatidae (Thermosphaeroma subequalum) is described from thermal waters (32° –35dgC) in Big Bend National Park, Brewster Co., Texas. A new genus, Thermosphaeroma, is proposed to include the Texas species and other sphaeromatids from hot springs in the American Southwest and Mexico: Exosphaeroma dugesi (Dolffus, 1893) from Aguascalientes, Mexico, and E. thermophilum (Richardson, 1897) from Socorro, New Mexico.Supported by National Park Service Contract PX 7000 3 0502, awarded to Owen T. Lind, Baylor University.     

Mitochondrial DNA Variation and Phylogeography of the Ferruginous Pygmy-Owl (Glaucidium brasilianum)

Sequences from the mitochondrial cytochrome b gene were used to examine patterns of variation within and among populations of the ferruginous pygmy-owl (Glaucidium brasilianum) from both North America (including populations from Mexico) and South America. As currently conceived, G. brasilianum is paraphyletic, with North American and South American clades representing two distinct groups that should be recognized as the distinct species G. ridgwayi and G. brasilianum, respectively. Within the G. ridgwayi clade, populations from Arizona, Sonora, and Sinaloa are genetically distinct and share no mitochondrial haplotypes with populations occurring in Texas and other regions of Mexico. According to nested clade analysis this separation may be the consequence of past fragmentation that predates the origin of the Sonora desert. In addition, gene flow between the Arizona/Sonora/Sinaloa populations and the Texas/other Mexico populations is practically nonexistent, with estimates being approximately one individual every 10 generations. Collectively, these data suggest that the Arizona/Sonora/Sinaloa clade should be recognized as either a distinct subspecies or phylospecies from the group containing populations in Texas and the remainder of Mexico. These data should be used as guidelines for pygmy-owl recovery and conservation, as they meet the recommendations of task 3 of the pygmy-owl recovery plan that lists genetic data as essential information for pygmy-owl management.     

Genetic structure of American black bears in the desert southwest of North America: conservation implications for recolonization

American black bears (Ursus americanus) have recolonized parts of their former range in the Trans-Pecos region of western Texas after a >40-year absence. Assessment of genetic variation, structuring, gene flow, and dispersal among bear populations along the borderlands of Mexico and Texas is important to gain a better understanding of recolonization by large carnivores. We evaluated aspects of genetic diversity and gene flow for 6 sampling areas of black bears in southwestern North America using genotypic data from 7 microsatellite loci. Our results indicated that genetic diversity generally was high in the metapopulation of black bears in northern Mexico and western Texas. The episodic gene flow occurring via desert corridors between populations in northern Mexico and those in western Texas has permitted the establishment of only moderate levels of genetic structuring. Bayesian clustering analyses and assignment testing depicted the presence of 3 subpopulations among our 6 sampling areas and attested to the generally panmictic nature of bear populations in the borderlands region. The potentially ephemeral nature of the small populations in western Texas and genotypic characteristics of bears recolonizing these habitats attest to the importance of linkages along this portion of the borderlands of the United States and Mexico to effectively conserve and manage the species in this part of its range.     

Taxonomy of <Emphasis Type="Italic">Koeberlinia</Emphasis> (Koeberliniaceae)

Koeberlinia has a natural amphitropical distribution that includes the deserts of central Bolivia, northern Mexico, and the southwestern United States. Despite the long recognition of only one species, K. spinosa, field, herbarium, and SEM studies support the recognition of two species. Koeberlinia spinosa of northern Mexico and adjacent United States is recognized to consist of three varieties: K. spinosa var. spinosa of northeastern Mexico and the adjacent United States, K. spinosa var. tenuispina of the Sonoran Desert of southwestern Arizona, adjacent California, and northwestern Mexico, and K. spinosa var. wivaggii from south central Texas and northern Mexico to Arizona, which is described as new. Koeberlina holacantha, endemic to the deserts of Bolivia, is proposed as new.     

SURVIVAL PATTERNS IN FOUR PRAIRIE GRASSES TRANSPLANTED TO CENTRAL TEXAS

Transplanted clones of four widespread prairie grasses, Andropogon scoparius, A. gerardii, Panicum virgatum, and Sorghastrum nutans, that had survived in cultivation 1958-1962 in central Texas were studied without cultivation 1963-67 to determine survival patterns. In all four species, clones from northern and eastern sites in the United States were eliminated. Survival of A. scoparius was restricted to plants originating in central and southern Texas and in northern Mexico. Surviving clones of A. gerardii, P. virgatum, and S. nutans were chiefly of Texas origin but included other clones mostly from the south central United States. Population samples of the four species from a central Texas grassland community showed greatest survival in a multi-ramet comparison of clones originating from North Dakota to Mexico City and in a multi-clone comparison from six sites in Texas and one in New Mexico. While the superior adaptation to the local habitat by the local populations might have been expected, this study documented the survival potential of organisms in the local ecosystem.     

PHOTOPERIOD IN XANTHIUM POPULATIONS FROM TEXAS AND MEXICO

Photoperiodic responses of Xanthium strumarium L. originating between 19° N in Mexico and 34° N in Texas varied among seedlings grown from seed under controlled conditions. The critical night lengths form a gradient from 9.5 hr in northern Texas to 10.75 hr in southern Texas and northeastern Mexico. Populations with critical night lengths of 9.5 and 9.75 hr showed a longer interval to flower bud formation under cooler temperatures (24 C day/15 C night) than under warmer temperatures (30 C day/24 C night). Three of four populations with a 10.75-hr critical night length showed a shorter interval under the cooler temperature regime. Although the Texas populations demonstrate a strong correlation of photoperiodic response with latitude, the Mexico populations show diverse photoperiodic timing from approximately the same latitude. The study emphasizes that a combination of critical night length and ripeness-to-flower (maturity) response forms the basis for reproductive adaptation in different climatic regimes in Texas and Mexico.     

The effect of environmental factors on the growth rate of Karenia brevis (Davis) G. Hansen and Moestrup

The red tide dinoflagellate Karenia brevis (Davis) G. Hansen and Moestrup is noted for causing mass mortalities of marine organisms in the Gulf of Mexico. Most research has focused on culture isolates from the eastern Gulf of Mexico. In this investigation, we examine the effects of light, temperature and salinity on the growth rate of K. brevis from the western Gulf of Mexico. Growth rates of K. brevis were determined under various combinations of irradiance (19, 31, 52, 67, and 123 μmol m⁻² s⁻¹), salinity (25, 30, 35, 40 and 45), and temperature (15, 20, 25, and 30 °C). Maximum growth rates varied from 0.17 to 0.36 div day⁻¹ with exponential growth rates increasing with increasing irradiance. Little or no growth was supported at 19 μmol photons m⁻² s⁻¹ for any experiment. Maximum growth rates at 15 °C were much lower than at other temperatures. Maximum growth rates of the Texas clone (SP3) fell within the range of Florida clones reported in the literature (0.17–0.36 div day⁻¹ versus 0.2–1.0 div day⁻¹). The Texas clone SP3 had a very similar light saturation point compared to that of a Florida isolate (Wilson's clone) (67 μmol m⁻² s⁻¹ versus 65 μmol m⁻² s⁻¹), and light compensation (20–30 μmol m⁻² s⁻¹1). The upper and lower salinity tolerance of the Texas clone was similar than that of some Florida clones (45 versus 46 and 25 versus 22.5, respectively). In our study, the Texas clone had the same temperature tolerance reported for Florida clones (15–30 °C). While individual clones can vary considerably in maximum growth rates, our results indicate only minor differences exist between the Texas and Florida strains of K. brevis in their temperature and salinity tolerance for growth. While the literature notes lower salinity occurrences of K. brevis in nearby Louisiana, our isolate from the southern Texas coast has the higher salinity requirements typical of K. brevis in the eastern Gulf of Mexico.     

Genetic and developmental variation of hemoglobin in the deermouse,Peromyscus maniculatus

A genetic investigation of electrophoretic hemoglobin variants of the deermouse, Peromyscus maniculatus, shows three alleles, HbI ^f, HbI^r, and HbI ^o, at a duplicated site controlling the six adult phenotypes. The HbI ^fallele has not been described previously. The hemoglobin locus is not closely linked to the albino locus. Fetal hemoglobin is distinct from any of the adult components and has a slower electrophoretic mobility. The fetal phenotype changes to the adult type between the days 15 and 18 of prenatal life.     

Intraspecific mitochondrial DNA variation in the Colorado potato beetle,Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Restriction endonuclease analyses of mitochondrial DNA (mtDNA) were used to examine genetic variability and population structure inLeptinotarsa decemlineata (Say). A group of three enzymes, EcoRI, HpaI, and PstI, was used to reveal polymorphism both within and among some of the 10 populations tested, yielding 16 haplotypes in combination. The frequencies of these 16 haplotypes differed significantly across geographic regions, indicating some partitioning of mtDNA haplotypes. Estimates of mtDNA sequence divergence (δ) between haplotypes ranged from 0.016 to 0.135%, suggesting local differentiation of mtDNA in some populations. Analysis of these data suggests that Texas was colonized by more than one mtDNA lineage, most likely originating in Mexico. We hypothesize that a larger founder size for the initial introductions or high levels of variability in the parent population at the edge of the CPB expanding range led to the initial partitioning of haplotypes observed in samples from Texas.     

Isolation of Histoplasma capsulatum from a texas cave

Summary Sixty-three soil samples collected from caves in Texas and the Republic of Mexico were studied to determine the incidence of pathogenic fungi by the use of the flotation technique in mice.Histoplasma capsulatum was isolated from the Kickapoo cave in Texas, and there was some histopathological evidence of its presence in the soil of Devil' cave (Cueva del Diablo) in Mexico. In the latter case, an incidence of human contact with the cave which resulted in an illness is presented.     

Allorhogas pyralophagus [Hym.: Braconidae], a gregarious external parasite imported into texas,USA, for biological control of the stalkborerEoreuma loftini [Lep.: Pyralidae] on sugar cane

Allorhogas pyralophagus Marsh is a recently discovered doryctine braconid with potential for field trials against stalk borers infesting both large- and small- stemmed Graminacea. This external gregarious parasite was originally reared fromEoreuma loftini (Dyar) larvae infesting Johnson grass [Sorghum halepense (L.) Pers.] and sugar cane (Saccharum officinarum L.) from the states of Sinaloa and Nuevo Leon, Mexico. The parasite is easily reared in the laboratory using a wide range of host larvae [Diatraea spp.,E. loftini, Chilo sp. andTryporyza nivelli (F)]. Hosts are placed in grass stems or paper straws for exposure to ovipositing females.A. pyralophagus has been field released and recovered from the following hosts infesting sugar cane:E. loftini andD. saccharalis (F.) in Texas.Diatraea spp. in Trinidad,D. rufescens in Bolivia andT. nivella in Sumatra, Indonesia. Approved as Contribution No. TA-20743 of the Texas Agricultural Experiment Station.     

Clinal variation at aspartate aminotransferase-2 in spotted seatrout,Cynoscion nebulosus (Cuvier), inhabiting the north-western Gulf of Mexico

Clinal variation was observed at the aspartate aminotransferase-2 (AAT-2) locus in the marine fish Cynoscion nebulosus (Cuvier) inhabiting the bays and estuaries of the Texas and northern Mexico Gulf coasts. Frequency of the AAT-2(80) allele increased from 0.9% at Sabine Lake, Texas to 17.1% at Rio Soto La Marina, Mexico. A statistically significant correlation existed in the frequency of this allele with degrees north latitude and west longitude. This information, if properly incorporated into a comprehensive enhancement programme, could facilitate supplemental stocking success.     

Detecting Karenia brevis blooms and algal resuspension in the western Gulf of Mexico with satellite ocean color imagery

Blooms of the toxic dinoflagellate, Karenia brevis, have had detrimental impacts on the coastal Gulf of Mexico for decades. Detection of Karenia brevis blooms uses an ecological approach based on anomalies derived from ocean color imagery. The same anomaly product used in Florida produces frequent false positives on the Texas coast. These failures occurred during wind-driven resuspension events. During these events resuspension of benthic algae significantly increases chlorophyll concentrations in the water, resulting in confusion with normal water column phytoplankton, such as Karenia. A method was developed to separate the resuspended chlorophyll from the water column chlorophyll, decreasing the false positives used with the detection method.     

Differentiation in habitat response in taxodium distichum,taxodium mucronatum,platanus occidentalis,and liquidambar styraciflua from the United States and Mexico

Summary Habitat specialization in populations of three broadly distributed trees includes adaptive differentiation to day length and temperature. Low sensitivity to environmental cues is the adaptive strategy of the southernmost populations (from northeastern Mexico). Early cessation of growth and sensitivity to the environment is adaptive for the northernmost populations (southern Illinois). Intermediate responses characterize trees of Texas. In a comparison under four photoperiod-temperature conditions, the Mexico plants were adapted to the longest growing season. Under out-of-doors conditions in central Texas, these trees from Mexico continue to demonstrate adaptive strategies different from those of Texas or Illinois trees. Stipule production and leaf area inPlatanus showed modifications correlated with latitude. Northernmost trees had the smallest leaves and did not produce stipules under 12-h day lengths and 24–15 °C temperatures. The Mexico trees had stipules under each of the four experimental conditions. The results suggest that populations of deciduous trees in a given climate are selected toward convergence in some responses to that climate. As a result, populations of the three trees resemble each other in behavior in a given ecosystem. Research funds were provided by a grant from the U.S. Forest Service and from National Science Foundation Grant GB-6097. I acknowledge help of David S. May and George J. Williams.     

Development and application of LSU rRNA probes for Karenia brevis in the Gulf of Mexico, USA

The brevetoxin producing dinoflagellate, Karenia brevis, is the target of several monitoring and research programs in the Gulf of Mexico, where it forms extensive and frequently long-lived annual blooms that can cause human intoxication and fish kills, as well as severe economic losses to coastal communities. Rapid, reliable methods for the detection and enumeration of K. brevis cells, as well as their discrimination from morphologically similar species, are valuable tools for managers and scientists alike. Our aim was to produce a species-specific molecular probe that would serve as a tool to facilitate the efficient and reliable detection of K. brevis in the Gulf of Mexico. We sequenced a fragment of the large-subunit ribosomal RNA gene (LSU rDNA) from five K. brevis cultures isolated from the Texas Gulf coast, the Florida Gulf coast, and the Atlantic coast of Florida, and detected no differences among these isolates. A consensus sequence was thus compiled and compared to a previously published sequence from Karenia mikimotoi, the closest known phylogenetic relative to K. brevis, for the purpose of identifying unique K. brevis signature sequences. Fluorescently-labeled (FITC) oligonucleotide probes targeting these regions of the K. brevis LSU rRNA were designed to include at least two base pair differences, as compared to K. mikimotoi. Among seven probes designed, one uniquely identified all K. brevis isolates to the exclusion of all other species tested (Kbprobe-7), including a Gulf of Mexico K. mikimotoi isolate (Sarasota, FL) and several additional Gymnodinium species, as well as other dinoflagellate, diatom, and raphidophyte taxa. Importantly, K. brevis cells in samples taken during a 2001 bloom, fixed with a mixture of modified saline ethanol and 10% formalin, and stored at 4 °C for 7 months were successfully labeled with Kbprobe-7. In addition, preliminary analysis of labeled cells by flow cytometry revealed that K. brevis could be distinguished from K. mikimotoi in solution, suggesting other potential applications of this probe.     

Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter.     

Phylogeography of a widespread small carnivore,the western spotted skunk (Spilogale gracilis) reveals temporally variable signatures of isolation across western North America

We analyzed phylogeographic patterns in the western spotted skunk, Spilogale gracilis Merriam, 1890 (Carnivora: Mephitidae) in relation to historical events associated with Pre‐Pleistocene Divergence (PPD) and Quaternary climate change (QCC) using mitochondrial DNA from 97 individuals distributed across Western North America. Divergence times were generated using BEAST to estimate when isolation in putative refugia occurred. Patterns and timing of demographic expansion was performed using Bayesian skyline plot. Putative climatic refugia resulting from Quaternary climate change were identified using paleoecological niche modeling and divergence dates compared to major vicariant events associated with Pre‐Pleistocene conditions. We recovered three major mitochondrial clades corresponding to western North America (California, Baja, and across the Great Basin), east‐central North America (Texas, central Mexico, New Mexico), and southwestern Arizona/northwestern Mexico. Time to most recent common ancestor for S. gracilis occurred ~1.36 Ma. Divergence times for each major clade occurred between 0.25 and 0.12 Ma, with signature of population expansion occurring 0.15 and 0.10 Ma. Ecological niche models identified three potential climatic refugia during the Last Interglacial, (1) west coast of California and Oregon, (2) northwestern Mexico, and (3) southern Texas/northeastern Mexico as well as two refugia during the Last Glacial Maximum, (1) western USA and (2) southern Texas/northeastern Mexico. This study supports PPD in shaping species‐level diversity compared to QCC‐driven changes at the intraspecific level for Spilogale, similar to the patterns reported for other small mammals (e.g., rodents and bats). Phylogeographic patterns also appear to have been shaped by both habitat and river vicariance, especially across the desert southwest. Further, continuing climate change during the Holocene coupled with anthropogenic modifications during the Anthropocene appears to be removing both of these barriers to current dispersal of western spotted skunks.     

The fall migration flyways of monarch butterflies in eastern North America revealed by citizen scientists

The migration of monarch butterflies (Danaus plexippus) from Canada and the United States to overwintering sites in Mexico is one of the world’s most amazing biological phenomena, although recent threats make it imperative that the resources needed by migrating monarchs be conserved. The most important first step in preserving migration resources—determining the migration flyways—is also the most challenging because of the large-scale nature of the migration. Prior attempts to determine the flyways using mark-recapture techniques with wing tags gave some clues, but this important information has never been fully obtainable until now. In 2005 the citizen-science program, Journey North, initiated a project that asked participants to record sightings of overnight roosts of monarchs during their fall migration, and this project now provides an ideal way to illustrate the flyways used by monarchs on their way to Mexico, with the assumption that roost locations indicate migration routes. We used 3 years of this data to elucidate the flyways on a continent-wide scale, that revealed two distinct flyways, but only one appears to lead directly to Mexico. This main, ‘central’ flyway begins in the American Midwest states and southern Ontario, then continues south-southwest through the states of Kansas, Missouri, Oklahoma and Arkansas, and finally passes through Texas and northern Mexico. These data also highlighted a separate, smaller flyway along the eastern and coastal states, but there was a noticeable lack of roost sightings in this flyway at lower latitudes. Since there are few recoveries of marked monarchs in Mexico originating from coastal areas, we compared the timing of roost formation in this ‘eastern’ flyway with the main, central flyway. Roosts in the eastern flyway lagged behind the central roosts in timing, suggesting that monarchs traveling in this flyway have a reduced chance of making it to the Mexico wintering site. Combined, our evidence indicates that locations in the central flyway should be considered priority areas for conserving migration resources.     

Trichinella infection in wildlife of the southwestern United States.

Several potential mammalian reservoirs of sylvatic species of Trichinella were examined from Texas, New Mexico, and Arizona. During 1998-99, tongues were collected from a black bear (Ursus americanus) in Arizona; from 9 black bears, a coyote (Canis latrans), and a mountain lion (Felis concolor) in New Mexico; and from 154 coyotes, 32 raccoons (Procyon lotor), 13 opossums (Didelphis marsupialis), 4 ocelots (Leopardus pardalis), 3 bobcats (Lynx rufus), and 5 feral hogs (Sus scrofa) in southern Texas. Larvae of Trichinella murrelli were identified by a multiple-polymerase chain reaction analysis in 1 black bear (11.1%) from New Mexico and in 7 coyotes (4.5%) of Texas, whereas Trichinella spiralis larvae were detected in the black bear of Arizona. This is the first report of Trichinella infection in wildlife of New Mexico and Texas and extends the distribution of T. murrelli into the southwestern United States near the border of Mexico.