Is Territory Defence related to Plumage Ornaments in the King Penguin Aptenodytes patagonicus?

Colourful ornaments in monogamous birds may be directed at potential mates or other conspecifics to signal individual condition, reproductive status or fighting ability, especially in monogamous and territorial species. We investigated whether the size of the orange auricular patch may be an indicator of aggressiveness in the king penguin Aptenodytes patagonicus , a monogamous and territorial seabird. The relationship between auricular patch size and defence behaviour was explored relative to territory location (centre vs. periphery of the colony), period of reproduction (early vs. late), state of reproduction (incubation vs. brooding) and sex. The proportion of time spent in territorial defence and the rate of aggressive behaviours were positively correlated with auricular patch size, mainly because central birds were more aggressive than peripheral birds and also had larger patch sizes. The period of reproduction, state of reproduction and sex did not interact with patch size to affect aggressiveness. Our results suggest that the size of the auricular patch in king penguins may be a reliable signal allowing individuals to evaluate the quality of mates or competitors in terms of aggressiveness. Whether aggressiveness is directly linked to patch size or indirectly through body condition, however, remains to be determined. In any event, birds with larger patches seem to gain central territories in the colony, thereby increasing their reproductive success. Finally, our study adds to the growing evidence that the evolution of sexually monomorphic ornaments may stem from mutual sexual selection.     

Weather,microclimate, and energy costs of thermoregulation for breeding Adélie Penguins

Summary We measured meteorological conditions and estimated the energy costs of thermoregulation for young and adult Adélie Penguins (Pygoscelis adeliae) at a breeding colony near the Antarctic Peninsula. Air temperatures averaged < 5°C and strong winds were frequent. Operative temperatures (T_e) for adults ranged from –8 to 28°C, averaging 5–6°C, for the period from courtship to fledging of chicks. The average energy cost of thermoregulation (C_th) for adult penguins was equivalent to 10–16% of basal metabolism. C_th comprised about 15% of the estimated daily energy budget (DEB) of incubating adults, but only about 1% of the DEB of adults feeding chicks. The T_e's for chicks older than 14 days ranged from 0 to 31°C, averaging 8.0 C. The C_th for downy chicks ranged from about 31% of minimal metabolic rate (MMR) in 1 kg chicks to about 10% of MMR in 3 kg chicks. Between initial thermal independence (age 12–14 days) and the cessation of parental feeding (age 35–40 days), chicks use about 10–11% of assimilated energy for thermoregulation. C_th is equivalent to about 17% of the MMR of fledglings during their 2–3 week fast. We observed no indication of thermal stress (i.e., conditions in which birds cannot maintain stable T_b) in adults and no indication of cold stress in any age class. However, on clear, calm days when air temperature exceeds 7–10°C for several hours, downy chicks are vulnerable to lethal hyperthermia.     

Spontaneous micronucleus frequency and age: what are normal values?

Micronucleus frequency in epidemiological studies of human exposure has become a preferred biomarker. A generally recognized observation is that micronucleus frequency increases with age. One requirement for comparison of data, which is being generated in many countries, is some common agreement about what constitutes a typical or normal background frequency of micronuclei. This is also a requirement when examining any individual value, especially one which might be considered an outlier. A mean value for normal micronucleus frequency with age is developed via the analysis of multiple studies, all of which employed large population bases and generally were conducted with the intent of determining population values. The result is presented here, with the understanding that it may over- or under-estimate the actual values in certain populations.     

Extending Darwin’s analogy: Bridging differences in concepts of selection between farmers, biologists, and plant breeders

Darwin developed his theory of evolution based on an analogy between artificial selection by breeders of his day and “natural selection.” For Darwin, selection included what biologists came to see as being composed of (1) phenotypic selection of individuals based on phenotypic differences, and, when these are based on heritable genotypic differences, (2) genetic response between generations, which can result in (3) evolution (cumulative directional genetic response over generations). The use of the term “selection” in biology and plant breeding today reflects Darwin’s assumption—phenotypic selection is only biologically significant when it results in evolution. In contrast, research shows that small-scale, traditionally-based farmers select seed as part of an integrated production and consumption system in which selection is often not part of an evolutionary process, but is still useful to farmers. Extending Darwin’s analogy to farmers can facilitate communication between farmers, biologists, and plant breeders to improve selection and crop genetic resource conservation.     

What are the relations between mechanics, gait parameters, and energetics in terrestrial locomotion?

Are the different energy-conserving mechanics (i.e., pendulum and spring) used in different gaits reflected in differences in energetics and/or stride parameters? The analysis included published data from several species and new data from horses. When changing from pendulum to spring mechanics, there is a change in the slope of metabolic rate (MR) vs. speed in all species, in birds and quadrupeds there is no step increase, and in humans there are conflicting reports. At the trot-gallop transition, where quadrupeds are hypothesized to change from spring mechanics to some combination of spring and pendulum mechanics, there is a change in slope of MR vs. speed in horses but not in other species. Stride frequency (SF) is a logarithmic function of walking speed in all species, a linear function of trotting/running speed, and nearly independent of speed in galloping. In humans and horses there is a discontinuity in SF at the walk-trot (run) transition but not in birds. The slope of time of contact vs. speed does not change with mechanics in most species, but it does in humans. In horses and humans, there is a discontinuity at the walk-trot (run) transition and data for other species do not permit generalization. Duty factor (DF) in humans is greater than 0.5 in walking (pendulum mechanics) and less than 0.5 when running (spring mechanics). However, this is not true in many species that have DF>0.5 at the lowest speeds where they use spring mechanics. When trotting at low speeds, horses use forelimb DF>0.5 and hind limb DF<0.5. Thus, it is confusing to distinguish between walking and running by DF.     

Reaction between nitric oxide,glutathione, and oxygen in the presence and absence of protein: How are S-nitrosothiols formed?

The reaction between NO, thiols, and oxygen has been studied in some detail in vitro due to its perceived importance in the mechanism of NO-dependent signal transduction. The formation of S-nitrosothiols and thiol disulfides from this chemistry has been suggested to be an important component of the biological chemistry of NO, and such subsequent thiol modifications may result in changes in cellular function and phenotype. In this study we have reinvestigated this reaction using both experiment and simulation and conclude that: (i) S-nitrosation through radical and nonradical pathways is occurring simultaneously, (ii) S-nitrosation through direct addition of NO to thiol does not occur to any meaningful extent, and (iii) protein hydrophobic environments do not catalyze or enhance S-nitrosation of either themselves or of glutathione. We conclude that S-nitrosation and disulfide formation in this system occur only after the initial reaction between NO and oxygen to form nitrogen dioxide, and that hydrophobic protein environments are unlikely to play any role in enhancing and targeting S-nitrosothiol formation.     

Halocins: are they involved in the competition between halobacteria in saltern ponds?

Many representatives of the family Halobacteriaceae ("halobacteria") excrete halophilic bacteriocins (halocins) that inhibit the growth of other halobacteria. In spite of the fact that halocin production is widespread among the Halobacteriaceae, no information is available on their ecological significance. To test whether halocins may play a role in the interspecies competition between dif-ferent types of halobacteria in saltern crystallizer ponds inhabited by dense communities of these red halophiles, we assayed for halocins active against a variety of halobacteria in salterns from different locations worldwide. Detection of halocin activity was based on the inhibition of growth of indicator organisms on agar plates, the decreased incorporation of radiolabeled substrates, and microscopic examinations. No halocin activity was detected in any of the brines examined, in spite of the fact that halocin production was demonstrated in cultures of most microorganisms isolated from these brines. Thus, the contribution of halocins in the competition between different halobacteria in hypersaline aquatic environments is probably negligible. Received: July 29, 1999 / Accepted: October 18, 1999     

Quo vadis amphibia? Global warming and breeding phenology in frogs,toads and salamanders

As the earth is getting warmer, many animals and plants have shifted their timing of breeding towards earlier dates. However, there is substantial variation between populations in phenological shifts that typically goes unexplained. Identification of the different location and species characteristics that drive such variable responses to global warming is crucial if we are to make predictions for how projected climate change scenarios will play out on local and global scales. Here we conducted a phylogenetically controlled meta‐analysis of breeding phenology across frogs, toads and salamanders to examine the extent of variation in amphibian breeding phenology in response to global climate change. We show that there is strong geographic variation in response to global climate change, with species at higher latitudes exhibiting a more pronounced shift to earlier breeding than those at lower latitudes. Our analyses suggest that this latitude effect is a result of both the increased temperature (but not precipitation) at higher latitudes as well as a greater responsiveness by northern populations of amphibians to this change in temperature. We suggest that these effects should reinforce any direct effect of increasing warming at higher latitudes on breeding phenology. In contrast, we found very little contribution from other location factors or species traits. There was no evidence for a phylogenetic signal on advancing breeding phenology or responsiveness to temperature, suggesting that the amphibians that have been studied to date respond similarly to global warming.     

Spying on your neighbours? Social information affects timing of breeding and stress hormone levels in a colonial seabird

A good overlap between offspring energetic requirements and availability of resources is required for successful reproduction. Accordingly, individuals from numerous species fine-tune their timing of breeding by integrating cues that predict environmental conditions during the offspring period. Besides acquiring information from their direct interaction with the environment (personal information), individuals can integrate information by observing the behaviours or performance of others (social information). The use of social information is often beneficial because the accumulated knowledge of conspecifics may represent a source of information more reliable than the intrinsically more limited personal information. However, although social information constitutes the major source of information in a wide range of contexts, studies investigating its use in the context of timing of breeding are scarce. We investigated whether black-legged kittiwakes (Rissa tridactyla) used social information to adjust the timing of egg-laying. We manipulated social information using a food-supplementation experiment, known to advance kittiwakes' reproductive phenology. We expected food-supplemented and unsupplemented pairs to delay and advance, respectively, their timing of laying when surrounded by a majority of neighbours from the opposite food-treatment. However, both unsupplemented and food-supplemented kittiwakes delayed egg-laying when surrounded by a higher proportion of neighbours from the opposite food-treatment. This result shows that kittiwakes use social information to time egg-laying, but that it is not used to match the seasonal peak of food availability. We suggest that when social and personal cues give contradictory environmental information, individuals may benefit from delaying laying to gather more information to make better decisions about investment into eggs. Further, we explored a potential proximate mechanism for the pattern we report. We show that baseline corticosterone, known to mediate reproductive decisions, was lower in unsupplemented females facing a higher proportion of food-supplemented neighbours. Altogether, our results suggest that to fine-tune their timing of laying, kittiwakes use complex decision-making processes in which social and personal information interplay.

     

Relationships between direct and indirect measures of central and total adiposity in children: What are we measuring?

Objective: The relationship between central and total fat measured by anthropometry, dual energy X‐ray absorptiometry, and magnetic resonance imaging (MRI) with each other and systolic blood pressure (SBP) was examined. Design and Methods: Participants of the Avon Longitudinal Study of Parents and Children were examined at ages 9, 11, 13, and 15 years (n = 3,796‐6,567). MRI was available on a subset of children at 11 (n = 156) and 13 (n = 95). Results: Body mass index (BMI) and waist circumference (WC) were highly correlated (r = 0.84‐0.91, across ages), and total body fat mass (TBFM) and trunk fat mass (TFM) were very strongly correlated (r ≥ 0.98). Among boys, BMI vs. WC explained a similar degree of variation in TBFM and TFM (41‐71% vs. 43‐76%, across age and overweight groups); in girls, BMI accounted for 62‐73% variance and WC 47‐69%. Adiposity measures were generally similarly correlated with SBP within age groups. Further, the relationship between intra‐abdominal adipose tissue (IAAT) volume and adiposity measures did not vary greatly at 11 (0.65‐0.67) and 13 (0.64‐0.67). Conclusions: BMI and WC contain a large amount of overlapping information as evidenced by their high correlation and similarly sized associations with fat mass, SBP, and IAAT. This suggests that WC may be an inadequate marker of central adiposity during childhood.     

Why are rare traits unilaterally expressed?: Trait frequency and unilateral expression for cranial nonmetric traits in humans

Based on an analysis of nonmetric trait databases from several large skeletal series in Northern Europe and South America, representing 27 bilateral traits, we report a predictable relationship between the frequency of nonmetric traits and the probability that they are expressed bilaterally. In a wider sampling of traits and populations, this study thus confirms the findings of an earlier study by Ossenberg ([1981] Am. J. Phys. Anthropol. 54:471-479), which reported the same relationship for two mandibular traits. This trend was previously explained by extending the multifactorial threshold model for discontinuous traits to incorporate either separate thresholds for unilateral or bilateral expression, or by a fuzzy threshold in which the probability of bilateral expression increases away from the median threshold value. We show that the trend is produced under the standard multifactorial threshold model for discontinuous traits simply if the within-individual or developmental instability variance remains relatively constant across the range of liability. Under this assumption, the number of individuals in which one side but not the other is pushed over the threshold for trait formation will be a larger proportion of the number of individuals expressing the trait when the trait frequency is low. As trait frequency increases, the significance of within-individual variance as a determinant of trait formation decreases relative to the genetic and among-individual environmental variance. These results have implications for interpreting nonmetric trait data as well as for understanding the prevalence of unilateral vs. bilateral expression of a wide variety of discontinuous traits, including dysmorphologies in humans.     

Eradication of scrapie with selective breeding: are we nearly there?

Background  

Following EU decision 2003/100/EC Member States have recently implemented sheep breeding programmes to reduce the prevalence of sheep with TSE susceptible prion genotypes. The present paper investigates the progress of the breeding programme in the Netherlands. The PrP genotype frequencies were monitored through time using two sets of random samples: one set covers the years 2005 to 2008 and is taken from national surveillance programme; the other is taken from 168 random sheep farms in 2007. The data reveal that although the level of compliance to the breeding programme has been high, the frequency of susceptible genotypes varies substantially between farms. The 168 sheep farms are a subset of 689 farms participating in a postal survey inquiring about management and breeding strategies. This survey aimed to identify how much these strategies varied between farms, in order to inform assessment of the expected future progress towards eradication of classical scrapie.     

Bruises in culled cows: when,where and how are they inflicted?

In Chile, cow carcasses present the highest bruise prevalence compared with other cattle categories; however, the causes of the bruises are frequently unknown. In this study, 52 cull cows were transported to the slaughterhouse in three batches under identical transport conditions. A combination of direct observation and video analyses was used to determine moment, pre-slaughter stage and cause of potential bruising events during the period from loading on the farm until stunning at the slaughterhouse. After slaughter, number of bruises, location on the carcass and characteristics of the bruises were assessed. Seventy-eight bruises were observed on 37 carcasses. Fifty-two bruises were linked back to their causal event. Results showed that 46% of these bruises were a result of interactions between animal and facility, and most of them were inflicted in the stunning box, 27% of the bruises originated from animal–animal interactions and were mostly inflicted during lairage, another 27% was a result of human–animal interactions and were mostly inflicted during loading and unloading of animals. The percentages of potential bruising events resulting in a bruise were 43%, 9% and less than 1% for animal–facility, human–animal and animal–animal interactions, respectively. Most bruises on the back site were inflicted when the animal was in the stunning box (91.2%), whereas bruises on the pin site were mostly (75%) inflicted during loading at the farm. One may conclude that in relative short journeys (⩽4 h) directly from farm to the slaughterhouse and long lairage times (>12 h), most bruises are the result of circumstances at the slaughterhouse. A substantial amount of these bruises could be avoided by proper animal handling and adequate stunning facilities.     

Why are there so many mimicry rings? Correlations between habitat,behaviour and mimicry in Heliconius butterflies

In the new world tropics there is an extravagant array of sympatric butterfly mimicry rings. This is puzzling under strictly coevolutionary (Müllerian) mimicry: all unpalatable species should converge as ‘co-mimics' to the same pattern. If mimicry has usually evolved in unpalatable species by one-sided (Batesian) evolution, however, it is easy to see that mimicry rings centred on different models could remain distinct. If mimicry rings were also segregated by habitat, a diversity of mimicry rings could be stabilized. In this paper we report correlations between behaviour and mimicry of nine unpalatable Heliconius species. It is already known that co-mimics fly in similar habitats, and non-mimics fly in different habitats, although there is much overlap. Contrary to a previous report, we find little difference in flight heights of heliconiine mimicry rings; all species fly from ground level to the canopy. However, co-mimics roost at night in similar habitats and at similar heights above the ground, but in different habitats and at different heights from species in other mimicry rings. Heliconius (especially the erato taxonomic group) are renowned for roosting gregariously; and co-mimics roost gregariously with each other more often than with non-mimics. Gregarious roosting is therefore common between species, as well as within species. There are thus strong links between mimicry and behavioural ecology in Heliconius. The paradoxical correlation between nocturnal roosting and visual mimicry is presumably explained by bird predation at dusk when roosts are forming, or at dawn before they have disbanded. Direct evidence of predation is lacking, but there are high rates of disturbance by birds at these times. These results, together with knowledge of the phylogeny of Heliconius, suggest that species from the melpomene-group of Heliconius have radiated to occupy mimetic niches protected by model species in the Ithomiinae and the erato-group of Heliconius. A variety of sympatric mimicry rings is apparently maintained because key models fail to converge, while more rapidly-evolving unpalatable mimics evolve towards the colour patterns of the models. The maintenance of mimetic diversity would be aided by the habitat and behavioural differences between mimicry rings revealed here, provided that different predators are found in different habitats. This explanation for the maintenance of multiple mimicry rings is more plausible for Heliconius mimicry than alternatives based on visual mating constraints, thermal ecology, or camouflage.