Temperature Effects on Locomotion and Activity Bioenergetics of Amphibians, Reptiles, and Birds

1) Large temperature differences have a measurable effect onectothermic power consumption both at rest and during locomotion,yet this question remains to be satisfactorily addressed inecological studies looking at optimal foraging strategy andperformance. 2) Acclimation may influence the enzyme complementpresent in ectotherms and this could influence the energeticcost and efficiency of locomotion for ectotherms. 3) There maybe an optimal temperature for ectothermic locomotion and thismay vary from species to species, yet we measure power consumptionduring locomotion uniformly at 30°C. 4) Endothermic locomotionas demonstrated by birds is temperature sensitive, as was shownby Paladino and King (1984). Although the locomotory cost maynot change, thermoregulatory adaptations allow the bird to usethe heat produced during locomotion in the cold to reduce thermoregulatorypower requirements. 5) Avian hypothermia and inactivity is nota last ditch effort to save energy, but a strategy that allowsendotherms to conserve energy reserves during inactivity orstressful environmental conditions.     

Secondary Productivity in Terrestrial Communities

Secondary productivity is one portion of energy flow in a community,which includes the ingestion and assimilation of energy, andthe expenditure of energy in metabolism by consumer organisms.The purpose of this paper is to describe the ecological significanceof energy flow in consumers and to discuss methods of measuringits components. Data pertaining to 20 terrestrial animal populationsare presented. About 20% of the energy assimilated by invertebratesis manifested as net production, while only about 2% of theassimilated energy is represented by net production in populationsof birds and mammals. The relationship between production andmetabolism appears to depend on the capacity for homeothermy.For a given amount of assimilated energy, homeotherms produceless than heterotherms.     

SLUG DAMAGE AND NUMBERS OF SLUGS IN OILSEED RAPE BORDERING ON GRASS STRIPS

In 1995, slug damage and numbers of slugs were estimated intwo grass strips and adjacent rape fields. Investigations beganas soon as rape seedlings emerged and lasted for five weeks.Slug damage to rape plants 1 m from the grass strips was significantlyhigher than at greater distances from the strips. Derocerasreticulatum was the most abundant slug species recorded in bothgrass strips and adjacent rape fields. Arion lusitanicus andArion fasciatus were much less abundant than D. reticulatum.In one field, D. reticulatum declined steadily with increasingdistance from the grass strips and therefore appeared to havecaused the majority of severe damage to rape plants close tothe strips. This finding was surprising because until now severeslug damage in oilseed rape beside semi-natural habitats hasbeen observed only where A. lusitanicus was abundant. (Received 12 November 1997; accepted 26 January 1998)     

Cholesterol Inhibition of Pentacyclic Triterpenoid Biosynthesis in Tetrahymena pyriformis*†

SYNOPSIS. Tetrahymena pyriformis synthesizes tetrahymanol and “diplopterol” from acetate, mevalonate or squalene. The formation of these pentacyclic triterpenoid alcohols is inhibited by the addition of cholesterol to the culture fluid of the ciliates. Cholesterol also inhibits the biosynthesis of squalene from acetate or mevalonic acid. The synthesis of other terpene derivatives from acetate and mevalonate continues in the presence of cholesterol, thus suggesting that a major block occurs after “isoprene” formation and before squalene formation. Further, inhibition of squalene conversion to the pentacyclic alcohols by cholesterol has been established.     

The common patterns of nature

We typically observe large‐scale outcomes that arise from the interactions of many hidden, small‐scale processes. Examples include age of disease onset, rates of amino acid substitutions and composition of ecological communities. The macroscopic patterns in each problem often vary around a characteristic shape that can be generated by neutral processes. A neutral generative model assumes that each microscopic process follows unbiased or random stochastic fluctuations: random connections of network nodes; amino acid substitutions with no effect on fitness; species that arise or disappear from communities randomly. These neutral generative models often match common patterns of nature. In this paper, I present the theoretical background by which we can understand why these neutral generative models are so successful. I show where the classic patterns come from, such as the Poisson pattern, the normal or Gaussian pattern and many others. Each classic pattern was often discovered by a simple neutral generative model. The neutral patterns share a special characteristic: they describe the patterns of nature that follow from simple constraints on information. For example, any aggregation of processes that preserves information only about the mean and variance attracts to the Gaussian pattern; any aggregation that preserves information only about the mean attracts to the exponential pattern; any aggregation that preserves information only about the geometric mean attracts to the power law pattern. I present a simple and consistent informational framework of the common patterns of nature based on the method of maximum entropy. This framework shows that each neutral generative model is a special case that helps to discover a particular set of informational constraints; those informational constraints define a much wider domain of non‐neutral generative processes that attract to the same neutral pattern.