Tetranucleotide microsatellite loci from eastern bluebirds Sialia sialis

We describe primers and polymerase chain reaction (PCR) conditions to amplify 18 tetranucleotide microsatellite DNA loci in eastern bluebirds (Sialia sialis). The primers were tested using individuals from two study sites in Georgia and South Carolina. Among individuals from the Georgia population (n = 23), the primer pairs developed in this study yielded an average of 6.6 alleles per locus (range 2–12), an average observed heterozygosity of 0.56 (range 0.24–0.96) and an average polymorphic information content of 0.65 (range 0.3–0.86). Among individuals from the South Carolina population (n = 19), the primer pairs yielded an average of 5.8 alleles per locus (range 2–9), an average observed heterozygosity of 0.56 (range 0.05–0.86) and an average polymorphic information content of 0.63 (range 0.29–0.83).     

The impact of the crayfish Orconectes virilis on aquatic macrophytes

SUMMARY. 1. The impact of crayfish on the biomass, density and shoot morphology of four submersed plant species was examined under semi-natural conditions. Male or female crayfish ( Orconectes virilis ) were held for 5 weeks at biomasses of 0, 5, 10 or 18 g m⁻² (live weight) in twelve plastic pools (4.67 m², surface area) containing Potamogeton richardsonii, Myriophyllum exalbescens, Nuphar variegatum and Sparganium eurycarpum .
2. Crayfish significantly affected biomass, density and/or shoot morphology of all four macrophyte species. Differences in the effect of crayfish on macrophyte growth were related to plant species, crayfish sex and activity, and the abundance of alternative foods.
3. The effect of female crayfish on macrophyte growth was generally stimulatory. Myriophyllum and Potamogeton biomass, Potamogeton density and Myriophyllum length increased in the presence of female crayfish, possibly due to the reduction in herbivorous snails as a result of crayfish predation. In contrast, plant growth decreased in the presence of male crayfish: Myriophyllum, Nuphar and Potamogeton biomass, Myriophyllum and Sparganium density, and Sparganium and Poiamogeton length were reduced at male crayfish biomasses between 5 and 18 g m⁻².
4. These results indicate that even relatively low densities of crayfish can greatly affect the growth of submersed aquatic plants. Because of their ability to modify aquatic macrophyte, macroinvertebrate and, ultimately, fish communities, the introduction of crayfish into lakes where they do not occur could have a major effect on the structure and composition of the littoral zone.     

Long-term effects of PO4 fertilization on the distribution of bryophytes in an arctic river

1. Each year since 1983, H₃PO₄ has been added continuously during the ice-free season to a P-limited tundra river (Kuparuk River, North Slope, Alaska). Effects on epilithic metabolism, invertebrate community structure and fish production developed quickly. 2. In 1990, 7 years after fertilization began, we noted extensive coverage by bryophytes within the fertilized reach of the river, where very little had been noted before. Bryophyte biomass from a limited set of quadrats taken in 1990 and 1991 yielded 17 ± 9 (SE) g dry mass m^?2 in control reaches and 322 ± 96 g dry mass m^?2 in fertilized reaches. 3. An initial survey of macroalgal and bryophyte cover in 1991 suggested that the moss Schistidium (Grimmia) agassizii was distributed in both control and fertilized reaches of the river. No clear difference in coverage by this species was found in either reach. 4. In contrast, two species of Hygrohypnum (H. alpestre and H. ochraceum) were found almost exclusively in the fertilized reach. An extensive point transect survey done in 1992, above, within and below the fertilized reach, indicated that increased cover and biomass of Hygrohypnum spp. were confined to the fertilized reach of the river. Detrended correspondence analysis clearly separated the macrophyte and macroalgal communities in the fertilized reach from those in the control and downstream reaches. 5. A fourth bryophyte species (Fontinalis neomexicana) also occurred almost exclusively in the fertilized reach, but was much less abundant than the Hygrohypnum species. 6. Analysis of total N and P in the tissues of the Hygrohypnum spp., and estimates of average coverage (～15%) and biomass (～150g dry weight m^?2) over an 8km fertilized reach, suggest that these species alone may have removed two-thirds of the P added in the fertilizer experiment. The bryophyte community in this river is likely to be the dominant sink for P in the fertilized reach.     

Morphological and molecular taxonomy of a new Daptonema (Nematoda,Xyalidae) with comments on the systematics of some related taxa

A new species of Daptonema is described based upon morphological characters and 18S rRNA sequence. Daptonema matrona sp. nov. was collected in Pina Basin (north‐eastern Brazil). It differs from all other species of the genus by the presence of reduced cephalic setae and straight spicules. These features require an adaptation of the generic diagnosis. Moreover, the females are characterized by intra‐uterine development of the offspring, considered herein as their major autapomorphic feature. Molecular systematic analyses supported Daptonema matrona sp. nov. as a distinct genetic and evolutionary lineage. The data also indicate hypotheses of taxonomic synonymies amongst some related taxa from Xyalidae as well as the paraphyly of Daptonema. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 1–15.