Contraception, reproduction and demography of free-ranging Etosha lions (Panthera leo)

The use of long-acting contraceptives as an effective population control mechanism for free-ranging lions was investigated during a three-year study in the Etosha National Park on five lion prides. Lions were immobilized with ketamine hydrochloride and xylazine hydrochloride. Following immobilization, lionesses were weighed, measured and aged, while serum steroid hormone levels were analysed and vaginal smears were obtained. Physical condition and sexual state were assessed. Individuals were used as control animals or given melengestrol acetate (contraceptive) implants, branded and released; the animals were observed for possible changes in behaviour, birth rate and mortality. Ten treated lionesses were recaptured at irregular intervals to reassess weight and steroid hormone levels, while three lionesses had their implants removed to determine if their fertility would return. The contraceptives prevented pregnancy, were reversible when removed and did not alter lion behaviour significantly, except that sexual behaviour was not recorded in treated lionesses.     

Influence of Liriomyza species (Diptera: Agromyzidae) and their host plants, on oviposition by Opius dissitus females (Hymenoptera: Braconidae)

Two factors, among others, influence the oviposition of Opius dissitus Muesebeck. The first was the host species, the second the plant upon which the pest host larvae develop. O. dissitus females prefer Liriomyza trifolii (Burgess) larvae over those of L. huidobrensis (Blanchard). O. dissitus females were more attracted to the larvae of L. trifolii or L. huidobrensis when these were present on courgette rather than tomato or lettuce.     

Involvement of thioredoxin y2 in the preservation of leaf methionine sulfoxide reductase capacity and growth under high light

Methionine (Met) in proteins can be oxidized to two diastereoisomers of methionine sulfoxide, Met‐S‐O and Met‐R‐O, which are reduced back to Met by two types of methionine sulfoxide reductases (MSRs), A and B, respectively. MSRs are generally supplied with reducing power by thioredoxins. Plants are characterized by a large number of thioredoxin isoforms, but those providing electrons to MSRs in vivo are not known. Three MSR isoforms, MSRA4, MSRB1 and MSRB2, are present in Arabidopsis thaliana chloroplasts. Under conditions of high light and long photoperiod, plants knockdown for each plastidial MSR type or for both display reduced growth. In contrast, overexpression of plastidial MSRBs is not associated with beneficial effects in terms of growth under high light. To identify the physiological reductants for plastidial MSRs, we analyzed a series of mutants deficient for thioredoxins f, m, x or y. We show that mutant lines lacking both thioredoxins y1 and y2 or only thioredoxin y2 specifically display a significantly reduced leaf MSR capacity (–25%) and growth characteristics under high light, related to those of plants lacking plastidial MSRs. We propose that thioredoxin y2 plays a physiological function in protein repair mechanisms as an electron donor to plastidial MSRs in photosynthetic organs.     

Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosae

The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae , a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects.     

The influence of age and sex on wing-tip pattern in adult Black-headed Gulls Larus ridibundus

A discriminant equation based on bill-depth and total head- and bill-length is provided to sex adult Black-headed Gulls Larus ridibundus . This equation is used to sex birds of known age. Relationships between age and morphometrics and between age and the black extent on the wing are then investigated both in males and females. Size of birds did not change with age but the black extent on the wing tended to decrease with age in both sexes. The tendency to become lighter with age may he an expression of senescence.     

BRYOZOAN MUD-MOUNDS FROM THE UPPER ORDOVICIAN JIFARAH (DJEFFARA) FORMATION OF TRIPOLITANIA, NORTH-WEST LIBYA

Abstract:  A bryozoan fauna from carbonate mud-mounds is described from subsurface well cores from the Upper Ordovician (Lower Ashgill) Jifarah (Djeffara) Formation of Tripolitania, north-west Libya. Among a diverse assemblage dominated by trepostomes, nine species of bryozoans are identified, including Jifarahpora libyensis gen. et sp. nov. Delicate and robust branching, encrusting and nodular bryozoan growth forms are all common. The bryozoan-rich limestones are mostly mudstones and wackestones, with bafflestone and floatstone textures, but the mounds apparently lack organic framework and microbial fabrics. Regional geophysical data indicate rapid thickness changes between wells, where mound complexes locally up to 100 m thick had limited topographic relief over the surrounding sea floor. The mounds formed in a high-latitude, cool-water carbonate belt that extended widely across the northern margin of Gondwana. Quaternary analogues from the Great Australian Bight suggest that these early Ashgill mounds may have developed in slope environments during an episode of glacial lowstand that preceded the late Ashgill, Hirnantian glacial event.