Food habits and dietary overlap of nongame insectivorous fishes in Flint Creek, Oklahoma, a western Ozark foothills stream

Insectivorous fishes were sampled from March, 1983 to February 1984, in Flint Creek, Delaware Co., Oklahoma. There was insignificant habitat segregation between Etheostoma spectabile and E. punctulatum and seasonal habitat partitioning between Cottus carolinae and both darters. Mature E. spectabile ate primarily chironomids and mayflies, whereas juveniles fed primarily on microcrustaceans. Mature E. punctulatum consumed fewer Ephemerella and Leptophlebia than E. spectabile , feeding on Stenonema and other crustaceans. Juvenile E. punctulatum fed mainly on amphipods and mayflies, and juvenile E. spectabile ate primarily microcrustaceans. Cottus carolinae elected primarily mayflies in spring - summer and chironomids in January - February. Coefficients of dietary overlap were highest between larger E. spectabile and juvenile E. punctulatum and lowest between immature E. spectabile and mature E. punctulatum . Overlap between the two darters was significantly correlated with differences in mean prey size (p E. spectabile was also significantly correlated to differences in mean prey sizes. Etheostoma spectabile generally preferred smaller prey than E. punctulatum . All three species avoided Stenelmis . Cottus carolinae avoided microcrustaceans. The study showed that resource partitioning among these three insectivorous fishes is affected by complex interactions of habitat and prey electivity, and prey size selectivity.         

The generic name of the North American musk turtles

Although several recent workers have used the name Sternothaerus for the North American musk turtles, the rules of priority render Sternotherus the correct name for them. The generic type fixation by Stejneger of S. odoratus is accepted.     

Numeric analysis of the lizard genus Sceloporus with special reference to cranial osteology

Phylogenetic relationships among Sceloporine genera are briefly discussed. Species relationships within the genus Sceloporus are analyzed, and evolutionary lines of descent are proposed. The genus Sceloporus is composed of three monophyletic groups: Group I, the most primitive, probably developed from Sator - like ancestral stock in Miocene times. This group speciated from stock similar to Sceloporus gadoviae in southern Mexico to S. merriami in the North and contains 7 species in 3 species groups. We propose that these species be included in the genus Lysoptychus Cope. Group II arose from Group I and evolved from centrally located Sceloporus pictus in all directions throughout Mexico. This intermediate group contains approximately 19 species in 5 species groups. Group III also arose from the primitive stock of Group I and radiated from several desert refugia created by Pleistocene glaciation. Evolution of this group in Mexico was generally from north to south with Sceloporus malachiticus extending as far south as Panama. This group contains approximately 33 species in 5 species groups.     

Three new species of Nearctic Isoperla (Plecoptera)

Nymphs and adults of three new species of Isoperla are described from reared material. I. sagittata is known only from southeastern Texas, I. Coushatta has been collected in East Texas and Oklahoma, and I. jewetti occurs in the Basin and Range Mountains of West Texas. The male aedeagii, female subgenital plates, and nymphal mouthparts are diagnostic in all three species.     

Tungsten isotope evidence from approximately 3.8-Gyr metamorphosed sediments for early meteorite bombardment of the Earth

The 'Late Heavy Bombardment' was a phase in the impact history of the Moon that occurred 3.8 4.0 Gyr ago, when the lunar basins with known dates were formed. But no record of this event has yet been reported from the few surviving rocks of this age on the Earth. Here we report tungsten isotope anomalies, based on the (182)Hf (182)W system (half-life of 9 Myr), in metamorphosed sedimentary rocks from the 3.7 3.8-Gyr-old Isua greenstone belt of West Greenland and closely related rocks from northern Labrador, Canada. As it is difficult to conceive of a mechanism by which tungsten isotope heterogeneities could have been preserved in the Earth's dynamic crust mantle environment from a time when short-lived (182)Hf was still present, we conclude that the metamorphosed sediments contain a component derived from meteorites.     

The use of space in living systems theory: Extensions and applications

Space, especially physical or geographical space, is a very important concept in living systems theory (LST). Indeed, along with time, it is included in the very definition of a concrete living system. But while time has its own critical subsystem in LST, space receives relative neglect. There is no space subsystem, but space is discussed in the boundary and supporter subsystems. The problem here is that discussion of the boundary emphasizes the regulation of matter-energy and information flows, while discussion of the supporter emphasizes vertical support rather than lateral spacing. The purpose of this paper is to rectify the relative neglect of spacing by unifying the scattered discussion of space in LST. After discussing space in the boundary and supporter subsystems at six levels (the organism, group, organization, community, society, and supranational), the paper extends and complements the literature of LST by discussing additional relevant literature on space, and by discussing possible applications at the six levels.     

An ancient cytokine,astakine, mediates circadian regulation of invertebrate hematopoiesis

Invertebrate circulating hemocytes are key players in the innate immune defense and their continuous renewal from hematopoietic tissues is tightly regulated in crustaceans by astakine, a new family of cytokines sharing a prokineticin (PROK) domain. In vertebrates, brain PROKs function as transmitters of circadian rhythms and we present evidence that hemocyte release from hematopoietic tissues in crayfish is under circadian regulation, a direct result of rhythmic expression of astakine. We demonstrate that the observed variation in astakine expression has an impact on innate immunity assessed as susceptibility to a pathogenic Pseudomonas species. These findings enlighten the importance of comparing immune responses at fixed times not to neglect circadian regulation of innate immunity. Moreover, our results entail an evolutionary conserved function for prokineticins as mediators of circadian rhythm, and for the first time show a role for this domain in circadian regulation of hematopoiesis that may have implications also in vertebrates.     

Distant metastasis occurs late during the genetic evolution of pancreatic cancer

Metastasis, the dissemination and growth of neoplastic cells in an organ distinct from that in which they originated, is the most common cause of death in cancer patients. This is particularly true for pancreatic cancers, where most patients are diagnosed with metastatic disease and few show a sustained response to chemotherapy or radiation therapy. Whether the dismal prognosis of patients with pancreatic cancer compared to patients with other types of cancer is a result of late diagnosis or early dissemination of disease to distant organs is not known. Here we rely on data generated by sequencing the genomes of seven pancreatic cancer metastases to evaluate the clonal relationships among primary and metastatic cancers. We find that clonal populations that give rise to distant metastases are represented within the primary carcinoma, but these clones are genetically evolved from the original parental, non-metastatic clone. Thus, genetic heterogeneity of metastases reflects that within the primary carcinoma. A quantitative analysis of the timing of the genetic evolution of pancreatic cancer was performed, indicating at least a decade between the occurrence of the initiating mutation and the birth of the parental, non-metastatic founder cell. At least five more years are required for the acquisition of metastatic ability and patients die an average of two years thereafter. These data provide novel insights into the genetic features underlying pancreatic cancer progression and define a broad time window of opportunity for early detection to prevent deaths from metastatic disease.     

Invasion and the evolution of speed in toads

Cane toads (Bufo marinus) are large anurans (weighing up to 2 kg) that were introduced to Australia 70 years ago to control insect pests in sugar-cane fields. But the result has been disastrous because the toads are toxic and highly invasive. Here we show that the annual rate of progress of the toad invasion front has increased about fivefold since the toads first arrived; we find that toads with longer legs can not only move faster and are the first to arrive in new areas, but also that those at the front have longer legs than toads in older (long-established) populations. The disaster looks set to turn into an ecological nightmare because of the negative effects invasive species can have on native ecosystems; over many generations, rates of invasion will be accelerated owing to rapid adaptive change in the invader, with continual 'spatial selection' at the expanding front favouring traits that increase the toads' dispersal.