Middle Pennsylvanian Ichnofauna from Eastern Oklahoma,USA

The Keota site, in the Middle Pennsylvanian (Desmoinesian) Keota Sandstone Member, McAlester Formation (Krebs Group) of Haskell County, Oklahoma, yields an extensive ichnofossil assemblage of arthropod trackways, insect resting traces, arthropod feeding and grazing traces, fish swimming traces, and tetrapod footprints. This ichnofossil assemblage occurs in a 0.8 to 1.5-m-thick unit of thinly laminated and ripple-laminated sandstone at the base of the Keota Sandstone Member that is interpreted as a tidal flat sandstone. The arthropod traces are assigned to the ichnotaxa Diplichnites gouldi Gevers types A and B, Diplopodichnus biformis Brady, Paleohelcura tridactyla Gilmore, Tonganoxichnus buildexensis Mángano, Buatois, Maples and Lanier, Gordia marina Emmons, cf. Cochlichnus sp. and Treptichnus bifurcus Miller. The fish swimming traces are assigned to Undichna britannica Higgs, and the tetrapod tracks to Notalacerta ichnosp. and Pseudobradypus ichnosp. The Keota ichnofossil assemblage thus documents the first North American Pennsylvanian record of Paleohelcura tridactyla and the first record of Pseudobradypus from the western United States. This ichnofossil assemblage also provides compelling evidence of a freshwater habitat in a tidal flat setting during deposition of the fossil-bearing sandstone at the Keota site. Indeed, the Keota ichnofossil assemblage is characteristic of a Carboniferous-Permian Tonganoxichnus assemblage that identifies nonmarine tidal flat settings.     

Multivariate morphometry and rates of morphologic evolution within the Pennsylvanian fusulinid Beedeina (Ardmore Basin,Oklahoma, USA)

Ten species in the genus Beedeina from Desmoinesian (Middle Pennsylvanian) rocks in the Ardmore Basin (southern Oklahoma, USA) were discriminated on the basis of 29 measured variates. Each species was characterized by its mean scores on the first and second axes in canonical variates analysis (CVA) and by its lowest stratigraphic occurrence in order to identify evolutionary lineages. The pumila → plattensis → erugata lineage involved overall size increase without appreciable changes in shape. The insolita → haworthi → aff. whitakeri → acme and insolita → cf. novamexicana → euryteines lineages both exhibited axial lengthening, but the former involved relative elongation and the latter involved relative inflation. CVA function coefficients were used to identify taxonomically important characters for the analysis of rates of morphologic evolution, and it was discovered that three of the five most important characters occur in the embryonic portion of the shell (proloculus diameter, half-length and wall thickness of the first volution). Rates of evolution are variable among ancestor-descendant pairs in the three lineages, but they do not differ significantly from rates documented in other groups of fossil and extant organisms. Apparent variation in rates is an artifact of the unequal time intervals over which morphologic change was measured, with shorter intervals resulting in faster rates. Among the five variates examined in all ancestor-descendant pairs (i.e., across a range of time intervals), proloculus size and half-length of the first and sixth volutions exhibited the fastest mean rates of change, whereas wall thickness in the first volution and radius vector of the fifth volution exhibited slower mean rates of change.     

Biohydrologic effects of eastern redcedar encroachment into grassland, Oklahoma, USA

Woody encroachment affects the biohydrology of rangelands worldwide and can increase evapotranspiration by increasing plant rooting depth, increasing the duration of the growing season, or by initiating a process of hydrologic recovery in formerly overgrazed landscapes. Eastern redcedar (Juniperus virginiana) is encroaching rapidly into rangelands in the Southern Great Plains of the USA, and beyond, including Oklahoma. However, the degree to which increasing growing season duration causes higher evapotranspiration after encroachment is not known. Here we show that increasing the duration of the growing season in north-central Oklahoma’s water-limited climate from seven months (April–October) to 12 months increases modeled evapotranspiration only marginally, from 95% to 97% of precipitation. However, this increase in evapotranspiration with woody encroachment into grassland corresponded to a two-thirds reduction in deep drainage. This study’s estimate of the hydrologic effects of eastern redcedar encroachment is likely to be highly conservative because it does not take into account the runoff-inducing effects of livestock grazing. Comparing simulated hydrologic fluxes in the present study to past work measuring runoff from grazinglands suggests that eastern redcedar encroachment into overgrazed rangelands is likely to increase evapotranspiration significantly. Whether or not eastern redcedar encroachment effects on evapotranspiration are discernable at the watershed scale will depend on the extent of encroachment throughout the watershed. Further research is necessary to quantify how the hydrologic effects of eastern redcedar encroachment vary due to climatic gradient.     

A new species of Isospora (Apicomplexa: Eimeriidae) from Carolina chickadee (Passeriformes: Paridae), from Oklahoma,USA

Systematic Parasitology - The Carolina chickadee, Poecile carolinensis Audubon is a relatively small songbird belonging to the tit and chickadee family Paridae. Feces from three P. carolinensis...     

Patterns of change over time in darter (Teleostei: Percidae) assemblages of the Arkansas River basin,northeastern Oklahoma,USA

Rivers and streams are among the most threatened ecosystems worldwide, and their fish assemblages have been modified by anthropogenic habitat alteration and introductions of non‐native species. Consequently, two frequently observed patterns of assemblage change over time are species loss and biotic homogenization. In the present study, we compared contemporary (2006–2007) and historical (1948–1955) assemblages of darters, a group of small benthic fishes of the family Percidae, in the Arkansas River drainage of northeastern Oklahoma, USA. Results showed species loss between the two sampling periods, with historical estimates of overall species diversity across the study area exceeding contemporary estimates by five to eight species. Assemblages showed a low degree of darter similarity based on species presence and absence, with pairwise site comparisons (Jaccard's similarity index) between historical and contemporary samples averaging < 0.35. No significant homogenization or differentiation of assemblages occurred. Range expansion of widespread species, one of the primary mechanisms of biotic homogenization, was not observed; rather, all species occurred at a smaller proportion of sites in contemporary samples. Our results highlight the threat posed by anthropogenic habitat alteration to taxonomic groups such as darters, most of which are habitat specialists. However, our results suggest that biotic homogenization is unlikely to occur in the absence of immigration, especially if assemblages are subjected to ‘novel disturbances’ such as dam construction and watershed‐scale habitat degradation which negatively affect all components of the assemblage.     

Nobloedischia rasnitsyni, a new genus and species of Oedischiidae (Orthoptera) from the Lower Permian Wellington Formation of Oklahoma, USA

Nobloedischia rasnitsynigen. et sp. n. (Oedischiidae) is described from the Lower Permian Wellington Formation of Noble County, Oklahoma. The genus is similar to both Petrelcana (Oedischiidae: Mezenoedischiinae) and Oedischia (Oedischiidae: Oedischiinae) and is left unplaced at the subfamily level. The new species is the twelfth Orthoptera species and the fourth species of Oedischiidae from these deposits.     

Changes in forest understory associated with Juniperus encroachment in Oklahoma,USA

Question: Does understory vegetation cover and richness decline along a gradient of increasing Juniperus virginiana midstory canopy cover and is that decline best correlated with litter accumulation? Location: Cross Timbers Forest in Payne County, OK, USA. Methods: We measured vegetation in forest gaps as well as forest areas without J. virginiana, at the inner and outer edge of J. virginiana canopies and near J. virginiana trunks (200 plots) and compared vegetation differences among location to light, litter, soil and microclimate variables. Results: Species richness (11 spp m^?2 to 6 spp m^?2) and summer vegetation cover (53.3% to 12.7%) declined with proximity to trunks. Regression indicated that richness declines (R²=0.08) and cover (R²=0.18) were best correlated with J. virginiana litter accumulation. Partial canonical correspondence analysis (pCCA) revealed two strong canonical axes, one related to litter/light and another to cover of Quercus spp. versus J. virginiana. Tree seedlings and woody vines dominated near J. virginiana. Forbs, graminoids and Quercus spp. seedlings were more common in areas without J. virginiana. Conclusions: Increasing J. virginiana and consequent litter additions alter understory biomass and composition and, through inhibiting Quercus spp. recruitment, may lead to changes in overstory composition. Decreases in herbaceous litter, which historically contributed to fuel accumulation, may have positive feedback effects on midstory encroachment by reducing the potential for prescribed burning.     

Presence of hyperplastic pectoral mammary glands in a white-footed mouse (Peromyscus leucopus) from a Superfund Site in Oklahoma, USA

Laboratory experiments have documented the effects of hormones and endocrine-disrupting compounds on mammary development in mammals. However, few observations of mammary hyperplasia have been presented for wild rodents. We describe hyperplastic mammary glands in a wild-caught white-footed mouse (Peromyscus leucopus) from an area contaminated with heavy metals.     

Reappraisal of Oklahomaichnus,a supposed amphibian trackway from the Pennsylvanian of Oklahoma,USA

Oklahomaichnus millsii Sarjeant, from the Pennsylvanian (Missourian) Nellie Bly Formation of Oklahoma, is not the trackway of a lepospondyl amphibian, as originally proposed. Instead, it is the undertrack of an arthropod.     

A new caryosporan (Apicomplexa: Eimeriidae) from flat-headed snake,Tantilla gracilis (Reptilia: Ophidia: Colubridae), from McCurtain County,Oklahoma, USA

The flat-headed snake, Tantilla gracilis Baird and Girard is a small reptile belonging to the family Colubridae. Feces from a single T. gracilis from McCurtain County, Oklahoma, USA, was collected and examined for coccidia; it was found to be passing a new species of Caryospora. Oöcysts of Caryospora sargentae n. sp. are spheroidal to typically subspheroidal with a moderately-pitted bi-layered wall, measure (L × W) 20.7 × 19.2 µm, and have a length/width (L/W) ratio of 1.1; a micropyle and oöcyst residuum were absent but one to several small, irregular to spheroidal masses of non-refractile debris within the oocyst was present as well as a polar granule attached to the inner oöcyst wall. Sporocysts are ovoidal and measure 15.0 × 11.0 µm, L/W 1.4; a nipple-like Stieda body is present as well as a distinct rounded sub-Stieda body. The sporocyst residuum is composed of a large, dense, irregular mass of various sized granules located between and often obscuring the sporozoites. This is the third coccidian described from the flat-headed snake. In addition, we include some data on the endogenous development of the coccidian.

     

Tornado damage of Quercus stellata and Quercus marilandica in the Cross Timbers,Oklahoma, USA

Questions: The Cross Timbers are a mosaic of savannas, grasslands and upland forests, occupying a significant portion of south‐central North America. Our questions here were (1) how does a severe tornado affect the two most dominant tree species of the area Quercus marilandica and Q. stellata with respect to damage and mortality; (2) how do such patterns vary as a function of tree size? What are the implications of disturbance for codominance in species‐poor systems? Location: The Cross Timbers in Oklahoma, USA. Methods: We established a 14.48‐ha permanent plot following a severe tornado in 2003. We identified, numbered and tagged each tree and recorded its diameter at breast height (DBH), spatial coordinates, status (dead or alive), and damage type. We examined (1) relative abundance before and after the tornado; (2) differences in damage and mortality, and (3) the influence of tree diameter on the probability of damage and mortality for each species. Results: Differences in species identity and tree characteristics were significantly related to tree mortality following the tornado, after accounting for spatial locations. The odds of mortality were 12.0 times greater for Q. marilandica than for Q. stellata. Such greater vulnerability of Q. marilandica versus Q. stellata was also reflected in changes in density and basal area. Tree diameter clearly influenced the damage and mortality pattern in Q. stellata; larger trees sustained more damage and mortality. However, Q. marilandica did not exhibit size‐dependent mortality. Conclusion: The tornado affected the two dominant species differently. The intra‐ and inter‐specific differences in windstorm susceptibility may allow coexistence of the two species and are potentially important in the dynamics of the Cross Timbers. Species more damaged might finally benefit from the wind disturbance due to their resprouting ability.     

Tree seedling survivorship,growth, and allocation in the Cross Timbers ecotone of Oklahoma,USA

In order to better understand tree dynamics and maintenance of the ecotone between eastern deciduous forest and tallgrass prairie, I planted seedlings of five different species into a Cross Timbers area in North West Oklahoma for one-year. The seedlings were planted in four different patch-types under two different herbivore treatments. I found that (1) out of the original 200 seedlings, 58 survived after one-year with lacebark elm (Ulmus parrifolia), osage orange (Maclura pomifera), and eastern redbud (Cercis canadensis) surviving the most and protection from herbivores increasing survivorship by more than an order of magnitude, (2) elm (Ulmus parrifolia) showed the slowest stem growth but protection from herbivory increased stem growth rate by approximately 50%, leaf area ratio was largest for elm (Ulmus parrifolia) but seedlings growing in sumac (Rhus copallina) patches had the smallest values, specific leaf area was the largest for orange (Maclura pomifera) seedlings with tree seedlings growing in grass patches showing greater values than those grown in other patches, and (3) leaf mass ratio was largest for elm (Ulmus parrifolia) with seedlings grown in sumac (Rhus copallina) patches showing the smallest values and rough-leaf dogwood (Cornus drummondii) had the most root biomass relative to shoot biomass compared to all other species. Results suggest tree invasion and establishment across this ecotone is influenced both by species identity and by the variation in resources associated with the distribution and patch dynamics of vegetation from both eastern deciduous forest and tallgrass prairie.     

Biogeography,ecoregions, and geomorphology affect fish species composition in streams of eastern Oklahoma,USA

Stream fish assemblages are structured by biogeographical, physical and biological factors acting on different spatial scales. We determined how physical factors, geomorphology and stream habitat, influenced fish species composition (presence–absence) in eastern Oklahoma, USA relative to the ecoregion and biogeographic effects previously reported. We sampled fish assemblages and surveyed geomorphology and habitat at 107 stream sites in the Boston Mountains, Ouachita Mountains, and Ozark Highlands ecoregions in eastern Oklahoma. Partial canonical correspondence analyses (pCCAs) and variance partitioning showed that patterns of endemism related to drainage basins and ecoregions explained important variation in fish species composition in all streams, but stream size and local channel morphology explained more variation overall. Stream size effects were most important in explaining variability in fish species composition in both northeastern and southeastern Oklahoma streams. Local channel morphology and substrate characteristics were secondarily important. Variables typically considered important as fish habitat (aquatic vegetation, etc.) had little effect on fish species composition.     

Long‐term directional changes in upland Quercus forests throughout Oklahoma,USA

Questions: (1) How have the composition and structure of undisturbed upland Quercus forests changed over 50 years across a large region and moisture gradient; (2) What factors are associated with long‐term and broad‐scale changes in these forests? Location: Oklahoma, USA. Methods: We re‐sampled 30 forest stands originally sampled in the 1950s across a large geographical area and compared basal area, tree density, and sapling density between the sampling periods using paired t‐tests, CCA, and DCA. We examined vegetation dynamics in the context of drought indices compiled for the sample period. Results: Total and Quercus stellata basal area and tree density increased, but Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana and woody species richness increased for all measures. DCA indicated that re‐sampled stands generally changed from Q. stellata–Q. marilandica‐dominated forests to forests with greater woody species richness and more J. virginiana. Q. stellata remained a dominant tree species; otherwise, composition shifted towards mesophytic and invasive woody species. Measurements taken in the 1950s immediately followed a major drought; whereas subsequent decades were significantly moister. Conclusions: Fire exclusion and drought may have played an important role in driving changes towards lower dominance by Quercus, increased importance of mesophytic and invasive species, and greater woody species richness. These phenomena are similar to those found in Quercus‐dominated forests throughout the northern hemisphere.     

Adverse health effects in Canada geese (Branta canadensis) associated with waste from zinc and lead mines in the Tri-State Mining District (Kansas, Oklahoma, and Missouri, USA)

Lead and zinc poisoning have been recorded in a variety of bird species, including migrating waterfowl such as Canada Geese (Branta canadensis), at sites contaminated with mine waste from lead and zinc mines in the Tri-State Mining District, Kansas, Oklahoma, and Missouri, USA. The adverse health impacts from mine waste on these birds may, however, be more extensive than is apparent from incidental reports of clinical disease. To characterize health impacts from mine waste on Canada Geese that do not have observable signs of poisoning, four to eight apparently healthy birds per site were collected from four contaminated sites and an uncontaminated reference site, and examined for physical and physiologic evidence of metals poisoning. Tissue concentrations of silver, aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead, selenium, thallium, vanadium, and zinc were determined by inductively coupled plasma mass spectroscopy. Adverse health effects due to lead were characterized by assessing blood δ-aminolevulinic acid dehydratase (ALAD) enzyme activity. Adverse effects associated with zinc poisoning were determined from histologic examination of pancreas tissues. Elevated tissue lead concentrations and inhibited blood ALAD enzyme activities were consistently found in birds at all contaminated sites. Histopathologic signs of zinc poisoning, including fibrosis and vacuolization, were associated with elevated pancreatic zinc concentrations at one of the study sites. Adverse health effects associated with other analyzed elements, or tissue concentrations indicating potentially toxic exposure levels to these elements, were not observed.     

A new species of Eimeria Schneider, 1885 (Apicomplexa: Eimeriidae) from the eastern gray squirrel,Sciurus carolinensis (Rodentia: Sciuridae: Sciurinae: Sciurini) from Oklahoma,USA

Systematic Parasitology - A new species of Eimeria Schneider, 1885 is described from an eastern gray squirrel (Sciurus carolinensis) from McCurtain County, Oklahoma, USA. Oöcysts of Eimeria...