Idle slow as you grow old: longitudinal age-related metabolic decline in a wild passerine

Physiological changes due to aging are intensively studied as they have far-reaching implications for the mechanistic and evolutionary theories of senescence. In this respect, metabolic rate has been suggested to play a role for the deterioration and damage of cells and tissues with age, partly due to the generation of reactive oxygen species. To mitigate such damage, individuals can be predicted to reduce basal metabolic rate (BMR) with age. This prediction has been verified in humans and some laboratory animals but never in wild animal populations. We analyzed the change in BMR within individuals across years in two wild populations of great tit (Parus major) differing in BMR. Great tits, living under stressful conditions towards the northern limit of their distribution, decreased their BMR as they aged whereas no such decrease was found in a southern population. Thus, we found a clear decline only in the population with the highest BMR levels. This study provides the first evidence of an age-related decline in BMR for a wild homeotherm.     

Descriptive and experimental evidence for timing-mediated polygyny risk in a pied flycatcher Ficedula hypoleuca population

In polygynous species with biparental care, mates are often acquired in succession. Most research has focussed on the cost of polygyny in secondary females, but primary females may also suffer from reduced paternal care. The likelihood of sharing a male may be higher for early laying females, which could counteract the fitness benefits of breeding early. In this study, we use 12 years of data on pied flycatchers Ficedula hypoleuca, to show that the likelihood of becoming a primary female of a polygynous male declines over the season. Moreover, we provide experimental evidence that early breeding elevates polygyny risk, through an experimental manipulation that introduced early breeding females to a population with later breeding phenology. We found that, independently of breeding date, primary females slightly more often experienced complete brood failures than monogamous females, but did not differ in number of fledged offspring among successful broods or number of locally returning recruits. However, apparent survival in subsequent years was substantially lower in primary females, indicating that they may compensate for reduced male care at the expense of future reproduction. Our study reveals that polygyny risk indeed increases with early breeding and entails a local survival cost for primary females. However, this cost is likely largely outweighed by fitness benefits of early breeding in most years. Hence it is unlikely that the increased polygyny risk of early breeding counteracts the fitness benefits, but it may reduce selection for breeding extremely early.     

Ontogeny of the Upper Cambrian (Furongian) Olenid trilobite Protopeltura aciculate (Angelin, 1854) from Skåne and Västergötland,Sweden

Abstract: The ontogeny of the trilobite Protopeltura aciculata (Angelin, 1854) is described on the basis of material from the upper Cambrian (Furongian) of Andrarum (Skåne) and Hjelmsäter (Västergötland), Sweden. P. aciculata is present in the Parabolina brevispina and Parabolina spinulosa zones. Protopeltura aciculata is represented by all stages of growth, from early protaspides to holaspides, although most of the specimens are disarticulated and precise degrees are unknown. The cranidia have therefore been allocated to five morphological groups. Cuticular sculpture of the cranidia changes throughout ontogeny. Large tubercles are present in earlier stages, disappear gradually in middle meraspid stages and are replaced with a very faint granulation. The transitory pygidium, relatively large and shield‐shaped with upwardly and backwardly directed marginal spines in early meraspides, later becomes very small, triangular‐shaped and lacking spines as a late meraspid and holaspid. The development of hypostomes and librigenae is also described. Protopeltura aciculata shows major intraspecific variations throughout development, especially regarding the pygidium where variation is much less constrained than in many other olenids. This high developmental plasticity may be a survival strategy for a trilobite living in a stressed environment. Protopeltura inhabited a dysoxic environment, possibly unusually prone to localised spreading of anoxic or toxic water. Some morphs may have been less vulnerable than others to such stresses, surviving by chance and thus enabling the species to continue.     

Omnivores as plant bodyguards—A model of the importance of plant quality

The importance of omnivores in ecological systems is increasingly being recognized, not least due to their intensified use as biocontrol agents in crop production. We model a simple plant–herbivore–omnivore (predator) system to explore the effects of plant suitability as food for omnivores on the outcome of omnivore–herbivore interactions. The model predicts that increasing plant suitability relative to herbivore suitability for the omnivore will catalyze the extinction of herbivores or omnivores, depending on the relative growth rate of omnivores feeding solely on plants or herbivores. When omnivore growth is higher on plants, either the omnivore or the herbivore goes extinct. When omnivore growth is higher on herbivores, the possible consequences are extinction, stable coexistence, and limit cycles, depending on the combination of species properties. Our results suggest that plants in some situations may evolve towards becoming more suitable to omnivores to escape detrimental herbivores and that breeders could manipulate crop suitability to omnivore species to reach a desired outcome of omnivore–herbivore interactions.     

Alkali and oxygen-alkali treatment of D-arabino-hexosulose and O-β-D-glucopyranosyl-(1 → 4)-d-arabino-hexosulose.

Benzilic acid rearrangement of D-arabino-hexosulose (1) and O-β-D-glucopyranosyl-(1→4)-D-arabino-hexosulose (2) favours formation of mannonic acid and mannonic acid moieties, respectively. The results show that formation of aldonic acid end-groups via terminal aldosulose moieties is of little importance during oxygen-hydrogencarbonate treatment of (1→4)-linked polysaccharides. The major reaction of 1 in the absence of oxygen involves loss of C-1 as formic acid. The enediol intermediate gives rise to pentoses and pentuloses (degraded completely at high alkalinity), and 3-deoxypentonic acids. The yield of 3-deoxypentonic acids is decreased in the presence of oxygen, whereas that of arabinonic, erythronic, and glycolic acids is increased. The main reaction of 2 giving rise to aliphatic hydroxy acids is β-elimination of the glucose moiety, yielding a tricarbonyl intermediate (3) which, in sodium hydrogencarbonate, is decomposed mainly to 3,4-dihydroxybutanoic and glycolic acids. In sodium hydroxide, 3-deoxypentonic acids are among the major reaction products. In addition, a complex mixture of u.v.-absorbing solutes is formed, some of which are held irreversibly by anion exchangers.     

Books from an environmental perspective—Part 2: e-books as an alternative to paper books

Purpose  

Information and communication technology (ICT) has been proposed as a means to facilitate environmental sustainability. Dematerialisation is one potential way of doing this. For books, this could be realized through using e-book readers, which share many of the qualities of printed media and have notably low-energy requirements during use. The main aim of this study was to analyse the environmental impacts of an e-book read on an e-book reader, and to identify key issues determining the magnitude of the impact. A second aim was to compare the e-book product system with a paper book product system using a life cycle perspective.     

An inhibitor from placenta specifically binds urokinase and inhibits plasminogen activator released from ovarian carcinoma in tissue culture

An inhibitor present in placenta and released in placental tissue culture forms specific complexes with each of two molecular forms of urokinase. Audoradiography demonstrated that the inhibitor shifted the electrophoretic position of ¹²⁵I-labelled urokinase. It did not change the migration of diisopropyl-fluorophosphate-inactivated ¹²⁵I-labelled urokinase, thereby indicating complex formation dependent on active serine site in urokinase. The inhibitor had a strong neutralizing effect on the plasminogen activators released from human ovarian carcinoma in tissue culture. The placental inhibitor might prove useful in inhibiting the fibrinolytic process necessary for proliferation of tumour vessels.     

Behavioural responses to co-occurring threats of predation and ultraviolet radiation in Daphnia

1. Organisms in the wild are faced with multiple threats and a common response is a change in behaviour. To disentangle responses to several threats, we exposed two differently sized species of the freshwater invertebrate Daphnia to solar ultraviolet radiation (UVR) and predation from either moving pelagic or benthic ambush predators.
2. Using an advanced nanotechnology-based method, we tracked the three-dimensional movements of those mm-sized animals at the individual level. Each behavioural trial was performed both under conditions resembling night (no UVR) and day (UVR) and we examined patterns of the depth distribution and swimming speed by Daphnia across three treatments: no predator (control); bottom-dwelling damselfly (Calopteryx sp.); and fish (stickleback, Pungitius pungitius) predators. We also quantified the actual predation rate by the two predators on the two Daphnia species, Daphnia manga and Daphnia pulex.
3. We show that individual Daphnia are able to identify predators with different feeding habitats, rank multiple and simultaneously occurring risks and respond in accordance with the actual threat; complex responses that are generally associated with larger animals.
4. In a broader context, our results highlight and quantify how a cocktail of everyday threats is perceived and handled by invertebrates, which advances our understanding of species distribution in space and time, and thereby of population dynamics and ecosystem function in natural ecosystems.