Mineral Elements in the Nutrition of Larger Mammals

The larger mammals, in spite of a wide diversity in diet, differcomparatively little in total mineral or ash content of thewhole body. Because of the quantity required, calcium and phosphorusare the most commonly deficient elements. Tetany caused by adeficiency of magnesium is a problem in many areas. Deficienciesin trace elements are frequently the most dramatic in termsof the problems presented and the rapid response to minute increasesin intake. The interrelationships, both direct and indirect,have caused nutritionists to realize that, in spite of manyadvances, there are many unanswered questions about the requirementsand functions of the mineral elements in the larger mammals.The bulk of research has been with domestic species, but thereis every reason to believe that wild herbivores are equallysusceptible to deficiencies in these important nutrients.     

Ontogeny of a Simple Locomotor System: Role of the Periphery in the Development of Central Nervous Circuitry

The development of locomotor systems in the lobster Homarusamericanus is described. The tail—flip escape responseis fully developed when the larvae hatch, and occurs withoutthe participation of giant fibers. The abdominal swimmeretsare undifferentiated at hatching, but are fully developed twoto three weeks later when the animals molt to the fourth larvalstage. Forward locomotion in the pelagic larvae is achievedusing thoracic swimming appendages until the fourth larval stage,when these degenerate and the swimmerets assume the locomotorrole. The hypothesis that peripheral structures specify the centralnervous connections of motoneurons during ontogeny was testedin the swimmeret system. Presumptive swimmeret appendages, includingprospective muscle and sense organs, were extirpated prior totheir differentiation in newly hatched larvae. The correspondingswimmeret motoneurons nevertheless grew and formed normal centralconnections, as evidenced by the appearance of normal patternsof rhythmic locomotor discharge and normal reflexes at the usualtime. Moreover, swimmeret motoneurons retained normal patternsof motor output even when the regeneration of their target appendageswas prevented for as long as two months. Therefore, the formationof normal motor output patterns during ontogeny is not dependentupon feedback from differentiated target muscle nor from senseorgans which normally monitor the results of the motor activity.     

Characterization of SSRs from the American lobster,Homarus americanus

The American lobster (Homarus americanus), a commercially important benthic marine crustacean, is widely distributed along the continental shelf of the western North Atlantic. The population substructure of this species remains poorly understood despite its economic value. Informative markers are required to clarify relationships between local populations. To this end, we developed eight polymorphic short sequence repeats (SSR) for the American lobster, which were derived from expressed sequence tags. Additionally, we tested four SSRs previously identified for the Norway lobster (Nephrops norvegicus L.) for cross‐species utility; only one of these showed polymorphism.     

From forest to plantation? Obscure articles reveal alternative host plants for the coffee berry borer,Hypothenemus hampei (Coleoptera: Curculionidae)

The coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae), is the most devastating insect pest of coffee throughout the world. The insect is endemic to Africa but can now be found throughout nearly all coffee‐producing countries. One area of basic biology of the insect that remains unresolved is that of its alternative host plants, i.e. which fruits of plants, other than coffee, can the insect survive and reproduce in. An in‐depth survey of the literature revealed an article by Schedl listing 21 genera in 13 families in which the insect was collected, mainly in the Democratic Republic of Congo. This overlooked reference, together with information provided in other early articles, suggests that H. hampei is polyphagous, and could provide, if confirmed in the field, critical information on the evolution of this insect's diet, ecology and host range. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ??, ??–??.     

Evaluating Survey Methods for Monitoring a Rare Vertebrate,the Sonoran Desert Tortoise

Abstract: Effective conservation requires strategies to monitor populations efficiently, which can be especially difficult for rare or elusive species where field surveys require high effort and considerable cost. Populations of many reptiles, including Sonoran desert tortoises (Gopherus agassizii), are challenging to monitor effectively because they are cryptic, they occur at low densities, and their activity is limited both seasonally and daily. We compared efficiency and statistical power of 2 survey methods appropriate for tortoises and other rare vertebrates, line-transect distance sampling and site occupancy. In 2005 and 2006 combined, we surveyed 120 1-km transects to estimate density and 40 3-ha plots 5 times each to estimate occupancy of Sonoran desert tortoises in 2 mountain ranges in southern Arizona, USA. For both mountain ranges combined, we estimated density to be 0.30 adult tortoises/ha (95% CI = 0.17–0.43) and occupancy to be 0.72 (95% CI = 0.56–0.89). For the sampling designs we evaluated, monitoring efforts based on occupancy were 8–36% more efficient than those based on density, when contrasting only survey effort, and 17–30% more efficient when contrasting total effort (surveying, hiking to and from survey locations, and radiotracking). Occupancy had greater statistical power to detect annual declines in the proportion of area occupied than did distance sampling to detect annual declines in density. For example, we estimated that power to detect a 5% annual decline with 10 years of annual sampling was 0.92 (95% CI = 0.75–0.98) for occupancy and 0.43 (95% CI = 0.35–0.52) for distance sampling. Although all sampling methods have limitations, occupancy estimation offers a promising alternative for monitoring populations of rare vertebrates, including tortoises in the Sonoran Desert.     

Hydraulic limitation not declining nitrogen availability causes the age‐related photosynthetic decline in loblolly pine (Pinus taeda L.)

Declining net primary production (NPP) with forest age is often attributed to a corresponding decline in gross primary production (GPP). We tested two hypotheses explaining the decline of GPP in ageing stands (14–115 years old) of Pinus taeda L.: (1) increasing N limitation limits photosynthetic capacity and thus decreases GPP with increasing age; and (2) hydraulic limitations increasingly induce stomatal closure, reducing GPP with increasing age. We tested these hypotheses using measurements of foliar nitrogen, photosynthesis, sap‐flow and dendroclimatological techniques. Hypothesis (1) was not supported; foliar N retranslocation did not increase and declines were not observed in foliar N, leaf area per tree or photosynthetic capacity. Hypothesis (2) was supported; declines were observed in light‐saturated photosynthesis, leaf‐ and canopy‐level stomatal conductance, concentration of CO₂ inside leaf air‐spaces (corroborated by an increase in wood δ¹³C) and specific leaf area (SLA), while stomatal limitation and the ratio of sapwood area (SA) to leaf area increased. The sensitivity of radial growth to inter‐annual variation in temperature and drought decreased with age, suggesting that tree water use becomes increasingly conservative with age. We conclude that hydraulic limitation increasingly limits the photosynthetic rates of ageing loblolly pine trees, possibly explaining the observed reduction of NPP.