Myxidium macrocheili n. sp. (Cnidospora: Myxidiidae) from the Largescale Sucker Catostomus macrocheilus Girard,and a Synopsis of the Myxidium of North American Freshwater Vertebrates*

SYNOPSIS. Myxidium macrocheili n. sp. is described from the gall bladder, bile and pancreatic ducts of Catostomus macrocheilus Girard (largescale sucker) in western Montana. This parasite is markedly host specific; the trophozoite is nonmotile, polysporous, spheroidal, elongated or irregular, often arched and rolled at the edges, and up to 2.5 mm in greatest length; the ecto- and endoplasm are distinct; the sporonts are disporoblastic. The bipolar spore is longitudinally striated, usually ellipsoidal in front view, slightly S-shaped in side view, and averages 11.7 × 6.6 × 6.3 μ; the suture line and ridge are distinct; the polar filaments are coiled 4–6 times. An illustrated synopsis and a key of the 19 species and 10 unnamed forms of Myxidium of North American freshwater vertebrates are presented. At present members of the genus are known to infect fishes, amphibians and a single species of reptile on this continent.     

Facility for studying the effects of elevated carbon dioxide concentration and increased temperature on crops

The requirements for the experimental study of the effects of global climate change conditions on plants are outlined. A semi-controlled plant growth facility is described which allows the study of elevated CO₂ and temperature, and their interaction on the growth of plants under radiation and temperature conditions similar to the field. During an experiment on winter wheat (cv. Mercia), which ran from December 1990 through to August 1991, the facility maintained mean daytime CO₂ concentrations of 363 and 692 cm³ m^?3 for targets of 350 and 700 cm³ m^?3 respectively. Temperatures were set to follow outside ambient or outside ambient +4°C, and hourly means were within 0.5°C of the target for 92% of the time for target temperatures greater than 6°C. Total photosynthetically active radiation incident on the crop (solar radiation supplemented by artifieal light with natural photoperiod) was 2% greater than the total measured outside over the same period.     

Phylogenetic relationships of the enigmatic land snail genus Prestonella: the missing African element in the Gondwanan superfamily Orthalicoidea (Mollusca: Stylommatophora)

The land snail superfamily Orthalicoidea, although generally assumed to be of Gondwanan origin, is considered by the majority of recent authors to be absent from the African continent. However, two poorly-known African genera, Aillya and Prestonella , have historically been referred to the orthalicoid family Bulimulidae s.l. Anatomical study of Aillya has subsequently shown it to be morphologically distinct from the Bulimulidae and referable to a family of its own, outside the Orthalicoidea, but Prestonella has remained an enigmatic taxon of unknown affinity. Using molecular and morphological evidence, we demonstrate conclusively that Prestonella is indeed a member of the Bulimulidae s.l. We thus confirm that this family is represented in Africa, and that it has a classical disjunct, tri-continental southern distribution. Thus, either the origin of the family must at the least predate the separation of Africa and South America in the Mid Cretaceous (under a vicariance scenario) or there must have been subsequent dispersal between the isolated Gondwanan fragments. In view of the limited dispersal ability of terrestrial snails, we consider the former more likely. Anatomically, Prestonella exhibits many character states thought to be plesiomorphic, suggesting a relationship with the subfamily Bulimulinae. Bayesian analysis of nuclear DNA sequence data places it as sister group (posterior probability = 1.0) to an Australasian clade comprising Bothriembryon and Placostylus . However, taxon sampling within the Orthalicoidea is currently inadequate to permit meaningful resolution of subfamilial affinity using molecular data. Similarly, although those orthalicoid taxa for which molecular data are available comprise a well-supported clade, the relationships of this clade to other stylommatophoran clades remain unresolved.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 203–221.     

Short‐ and long‐term costs of reproduction in a migratory songbird

Costs of reproduction represent a common life‐history trade‐off. Critical to understanding these costs in migratory species is the ability to track individuals across successive stages of the annual cycle. We assessed the effects of total number of offspring fledged and date of breeding completion on pre‐migratory body condition, the schedule of moult and annual survival in a migratory songbird, the Savannah Sparrow Passerculus sandwichensis. Between 2008 and 2010, moult was delayed for individuals that finished breeding later in the breeding period and resulted in reduced lean tissue mass during the pre‐migratory period, suggesting an indirect trade‐off between the timing of breeding completion and condition just prior to migration. Lean tissue mass decreased as the number of offspring fledged increased in 2009, a particularly cool and wet year, illustrating a direct trade‐off between reproductive effort and condition just prior to migration in years when weather is poor. However, using a 17‐year dataset from the same population, we found that parents that fledged young late in the breeding period had the highest survival and that number of offspring fledged did not affect survival, suggesting that individuals do not experience long‐term trade‐offs between reproduction and survival. Taken together, our results suggest that adult Savannah Sparrows pay short‐term costs of reproduction, but that longer‐term costs are mitigated by individual quality, perhaps through individual variation in resource acquisition.