The adequacy of GWPs as indicators of damage costsincurred by global warming

This article looks at the ability of Global Warming Potentials (GWPs) towork as indicators of equivalence for temperature development and damagecosts. We look at two abatement scenarios that are equivalent when using100-year GWPs: one scenario reduces short-lived gases, mainly methane(CH₄); the other scenario reduces carbon dioxide (CO₂).Despite their equivalence in terms of CO₂ equivalents, the scenariosdo not result in equal rates or levels of temperature change. The disparitiescontinue as we move further down the chain of causality toward damagecosts, measured either in terms of rate of climate change or level of climatechange. Compared to the CH₄ mitigation scenario, the CO₂mitigation scenario gives present value costs 1.3 and 1.5 times higher forlevel- and rate-dependent damage costs, respectively, assuming a discountrate of 3%. We also test the GWPs for other time horizons and theconclusions remain the same; using GWP as an index to reflect equivalentclimate effects and damage costs from emissions is questionable.     

Growth conditions affect carotenoid-based plumage coloration of great tit nestlings

 Carotenoid-based integument colour in animals has been hypothesised to signal individual phenotypic quality because it reliably reflects either foraging efficiency or health status. We investigated whether carotenoid-derived yellow plumage coloration of fledgling great tits (Parus major) reflects their nestling history. Great tit fledglings reared in a poor year (1998) or in the urban habitat were less yellow than these reared in a good year (1999) or in the forest. The origin of nestlings also affected their coloration since nestlings from a city population did not improve their coloration when transferred to the forest. Brood size manipulation affected fledgling colour, but only in the rural population, where nestlings from reduced broods developed more yellow coloration than nestlings from increased and control broods. Effect of brood size manipulation on fledgling plumage colour was independent of the body mass, indicating that growth environment affects fledgling body mass and plumage colour by different pathways. Received: 20 March 2000 / Accepted in revised form: 4 September 2000     

Genetic amniocentesis at 7–14 weeks of gestation

Genetic amniocentesis performed at 7–14 weeks of gestation was studied in a series of 138 patients of whom 50 wanted termination of pregnancy (⩽ 12 weeks). The material for analysis consisted of 132 samples due to two sampling failures and four samples being handled incorrectly. Forty-eight samples (36 per cent) were taken at 7–12 weeks of gestation, mainly transvaginally (36/48:75 per cent). The success rate of culture and karyotyping increased with the duration of pregnancy, but was only satisfactory from week 11 onwards. The time until harvest was then 14–15 days. The transvaginal approach is easy to perform and was accepted by the women, but we experienced bacterial or fungal overgrowth in 17 per cent of these samples, whereas no infection occurred in the samples taken transabdominally (n = 96). We conclude that genetic amniocentesis is feasible from week 11, but further studies concerning side effects, especially focusing on the procedure-related abortion risk, should be carried out before early amniocentesis is routinely applied.     

True trisomy 15 mosaicism,detected by amniocentesis at 12 weeks of gestation and fetal echocardiography

A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications.     

High resolution chromosomes from first trimester trophoblast cultures

A simple method for obtaining prometaphase chromosomes from cultured first trimester cells involves the addition of BrdU and FdU 11 h before harvest and ethidium bromide 1.5 h before harvest. High resolution R-banding is obtained by acridine orange staining.     

The significance of hotspots to lekking topi antelopes (<Emphasis Type="Italic">Damaliscus lunatus</Emphasis>)

Controversy has surrounded the question of why lek-breeding has evolved in certain ungulate species. Can the behavior be explained simply by males mapping onto a female distribution that is determined by factors unrelated to mating? Or are leks created because estrous females distinguish between males and favor males who cluster? Here I address these questions by looking at spatial distribution in lekking topi antelopes (Damaliscus lunatus). Contrary to the predictions of a model assuming male clustering in the zone of maximum female range overlap, territories were highly clustered also within this zone, and lek size correlated positively with population density. In support of models derived from the ideal free distribution of males onto female dispersion, leks were in areas with high female density during the rut. However, models not taking into account both individual variation in male quality and female mate preferences failed to explain the extreme male clumping also within high density areas, which was revealed by a strongly male-biased sex-ratio on leks. Additional support for the female preference-based model came from the finding that estrous females concentrated onto leks. Female preference for clustered males may develop if males initially follow an ideal free distribution of unequal competitors with high quality males slightly clustered at density hotspots; positive feedback between female benefits of preference for clustered males and male benefits of clustering could lead to contraction of the territorial network and lek behavior. Thus only the female preference-based model correctly predicted a negative correlation between male mating rate and resource density.     

Energy metabolism during development of eggs and larvae of gilthead sea bream (Sparus aurata)

Developing eggs and larvae of laboratory-reared gilthead sea bream (Sparus aurata) maintained in filtered seawater (40 ppt) at 18°C, were measured for oxygen uptake, ammonia excretion, contents of free amino acids (FAA), protein, fatty acids (FA) accumulated ammonia, and volumes of yolk-sac and oil globule. Absorption of the yolk coincided with the consumption of FAA and was complete ca. 100 h post-fertilisation. Amino acids from protein were mobilised for energy in the last part of the yolk-sac stage. Absorption of the oil globule occurred primarily after hatching following yolk absorption, and correlated with catabolism of the FA neutral lipids. Overall, FAA appear to be a significant energy substrate during the egg stage (60 to 70%) while FA from neutral lipids derived from the oil globule are the main metabolic fuel after hatching (80 to 90%).     

Adaptive significance of phytoplankton stickiness with emphasis on the diatom Skeletonema costatum

Diatom aggregate formation was analyzed using coagulation theory. Population dynamics models show that coagulation has an important impact on species succession during diatom blooms. When different species collide and form mixed aggregates this process causes interspecific interference competition within the diatom community. The outcome can be predicted by a set of simple differential equations. For a twospecies system the equations reduce to the Lotka-Volterra two-species competition model. The outcome of this interference competition depends on species-specific growth rates, cell sizes, stickiness and on the species composition of the seeding populations of a bloom. Due to mutual flocculation some species may disappear from the environment. Small and fast growing diatoms are favoured by high stickiness coefficients. The impact of stickiness on species succession was found to be most pronounced in eutrophic and hydrographically isolated environments. The sticking properties of the diatom Skeletonema costatum are discussed in an evolutionary context; we suggest that mutual coagulation increases the abundance of S. costatum relative to other diatom species in coastal areas. The model was tested on field data, and the predicted dynamics of a spring bloom was very similar to that observed.     

Echolocation in two very small bats from Thailand Craseonycteris thonglongyai and Myotis siligorensis

Summary The echolocation and hunting behavior of two very small bats, Craseonycteris thonglongyai (Hill) and Myotis siligorensis (Horsfield), from Thailand, were investigated using multiflash photographs, video, and high-speed tape recordings with a microphone array that allowed determination of distance and direction to the bats. C. thonglongyai is the world's smallest mammal and M. siligorensis is only slightly larger. Both bats hunted insects in open areas. The search signals of C. thonglongyai were 3.5 ms long multiharmonic constant frequency (CF) signals with a prominent second harmonic at 73 kHz repeated at around 22 Hz. The band width (BW) of the short terminal frequency modulated (FM) sweep increased during the very short approach phase. In the final buzz the CF component disappeared, the duration decreased to 0.2 ms, and the repetition rate increased to 215 Hz (Figs. 2, 3, 4). There was no drop in frequency in the buzz. The video recordings of C. thonglongyai indicated that it seizes insects directly with the mouth (Fig. 1). M. siligorensis produced 5.4 ms long CF search signals at 66 kHz. The repetition rate was around 13 Hz. In the approach phase an initial broad band FM sweep was added. The buzz consisted of two phases, buzz I and buzz II. Buzz 11 was characterized by short cry durations (around 0.3 ms), a constant high repetition rate (185 Hz), a distinct drop in frequency, and a prominent second harmonic (Figs. 5, 6, 7). The drop in frequency, apparently typical of vespertilionid bats, has been explained by physiological limitations in sound production. However, C. thonglongyai produced very short signals at very high repetition rates without any frequency drop. The drop may be of adaptive value since it enables M. siligorensis to produce very short signals with high sweep rates. The drop moves the pronounced second harmonic into the frequency range of most interest to the bat (Fig. 7D). The sweep rate in this frequency range may now increase to twice the maximum rate that the vocal cords can produce directly. C. thonglongyai and M. siligorensis belong to different superfamilies, Emballonuroidea and Vespertilionoidea, respectively. In spite of their phylogenetic distance they produce strikingly similar search signals of narrow BW around 70 kHz with high source levels (100–115 dB peSPL peak equivalent sound pressure level). We argue that the signal resemblance is due to the similarity in size and hunting behavior of the two bats both hunting insects in open areas. High frequencies are heavily attenuated in air, but because of their small size the bats are restricted to hunting small insects which only reflect echoes at high frequencies. Thus, the emitted frequency is probably the lowest possible given the prey size. Hence, the two bats can only maximize the range of their sonar by decreasing the BW and emitting high intensities. Correspondence to: A. Surlykke