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508 records returned

The biogeography of introgression in the critically endangered African monkey Rungwecebus kipunji.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the four years since its original description, the taxonomy of the kipunji (Rungwecebus kipunji), a geographically restricted and critically endangered African monkey, has been the subject of much debate, and recent research suggesting that the first voucher specimen of Rungwecebus has baboon mitochondrial DNA has intensified the controversy. We show that Rungwecebus from a second region of Tanzania has a distinct mitochondrial haplotype that is basal to a clade containing all Papio species and the original Rungwecebus voucher, supporting the placement of Rungwecebus as the sister taxon of Papio and its status as a ...
Source: Biology Letters - November 11, 2009 Category: Biology Authors: Roberts TE, Davenport TR, Hildebrandt KB, Jones T, Stanley WT, Sargis EJ, Olson LE Tags: Biol Lett Source Type: journals

Personality predicts spatial responses to food manipulations in free-ranging great tits (Parus major).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study is the first to show that personality traits predict the spatial response to experimentally induced changes in their natural environment. PMID: 19906682 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - November 11, 2009 Category: Biology Authors: van Overveld T, Matthysen E Tags: Biol Lett Source Type: journals

Organisms on the move: ecology and evolution of dispersal.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The symposium and workshop 'Organisms on the move: ecology and evolution of dispersal', held in Ghent (Belgium), 14-18 September 2009, brought together a wide range of researchers using empirical and modelling approaches to examine the dispersal process. This meeting provided an opportunity to assess how much cross-fertilization there has been between empiricists and theoreticians, to present novel insights on dispersal patterns in plants, animals and micro-organisms and to measure the progress made in examining the causes and consequences of dispersal. PMID: 19906683 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - November 11, 2009 Category: Biology Authors: Gibbs M, Saastamoinen M, Coulon A, Stevens VM Tags: Biol Lett Source Type: journals

Social influences of competition on impulsive choices in domestic chicks.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Social factors involved in the control of impulsiveness were examined in domestic chicks. In binary choices between a large/long-delay option (LL) and a small/short-delay alternative (SS), chicks that had been competitively trained in groups of three individuals showed fewer choices of LL than did those trained in isolation (experiment 1), suggesting that competition causes impulsive choice. In experiment 2, in order to identify the critical factor involved, we tested the effects of perceived competition (coincident feeding without interruption) and scrounging (gaining food without pecking bead) separately. To examine ...
Source: Biology Letters - November 11, 2009 Category: Biology Authors: Amita H, Kawamori A, Matsushima T Tags: Biol Lett Source Type: journals

Running-specific prostheses limit ground-force during sprinting.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Running-specific prostheses (RSP) emulate the spring-like behaviour of biological limbs during human running, but little research has examined the mechanical means by which amputees achieve top speeds. To better understand the biomechanical effects of RSP during sprinting, we measured ground reaction forces (GRF) and stride kinematics of elite unilateral trans-tibial amputee sprinters across a range of speeds including top speed. Unilateral amputees are ideal subjects because each amputee's affected leg (AL) can be compared with their unaffected leg (UL). We found that stance average vertical GRF were approximately 9 p...
Source: Biology Letters - November 4, 2009 Category: Biology Authors: Grabowski AM, McGowan CP, McDermott WJ, Beale MT, Kram R, Herr HM Tags: Biol Lett Source Type: journals

Safe sex: male-female coalitions and pre-copulatory mate-guarding in a fiddler crab.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In fiddler crabs both males and females defend territories that are essential for survival. Given pronounced sexual dimorphism in weaponry, how do weaponless females defend their territory from well-armed males? Using observational data and two simple experiments, we test whether male Uca annulipes protect their female neighbours from conspecific intruders. We show that males defend their female neighbours against male but not female intruders. We also show that females sometimes mate with their immediate neighbours. Male defence of female neighbours appears to represent both pre-copulatory mate-guarding and a territor...
Source: Biology Letters - November 4, 2009 Category: Biology Authors: Milner RN, Jennions MD, Backwell PR Tags: Biol Lett Source Type: journals

Effects of parental larval diet on egg size and offspring traits in Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report that in Drosophila melanogaster, parents raised on poor larval food laid 3-6% heavier eggs than parents raised on standard food, despite being 30 per cent smaller. Their offspring developed 14 h (4%) faster on the poor food than offspring of well-fed parents. However, they were slightly smaller as adults. Thus, the effects of parental diet on offspring performance under malnutrition apparently involve both adaptive plasticity and maladaptive effects of parental stress. PMID: 19875510 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - October 29, 2009 Category: Biology Authors: Vijendravarma RK, Narasimha S, Kawecki TJ Tags: Biol Lett Source Type: journals

Host ant independent oviposition in the parasitic butterfly Maculinea alcon.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Parasitic Maculinea alcon butterflies can only develop in nests of a subset of available Myrmica ant species, so female butterflies have been hypothesized to preferentially lay eggs on plants close to colonies of the correct host ants. Previous correlational investigations of host-ant-dependent oviposition in this and other Maculinea species have, however, shown equivocal results, leading to a long-term controversy over support for this hypothesis. We therefore conducted a controlled field experiment to study the egg-laying behaviour of M. alcon. Matched potted Gentiana plants were set out close to host-ant nests and n...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Fürst MA, Nash DR Tags: Biol Lett Source Type: journals

Extrafloral nectar content alters foraging preferences of a predatory ant.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We tested whether the carbohydrate and amino acid content of extrafloral nectar affected prey choice by a predatory ant. Fire ants, Solenopsis invicta, were provided with artificial nectar that varied in the presence of carbohydrates and amino acids and were then provided with two prey items that differed in nutritional content, female and male crickets. Colonies of fire ants provided with carbohydrate supplements consumed less of the female crickets and frequently did not consume the high-lipid ovaries of female crickets. Colonies of fire ants provided with amino acid supplements consumed less of the male crickets. Wh...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Wilder SM, Eubanks MD Tags: Biol Lett Source Type: journals

Mountain lions prey selectively on prion-infected mule deer.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examined whether mountain lions (Puma concolor) selectively prey upon mule deer (Odocoileus hemionus) infected with chronic wasting disease, a prion disease. We located kill sites of mountain lions in the northern Front Range of Colorado, USA, and compared disease prevalence among lion-killed adult (>/=2 years old) deer with prevalence among sympatric deer taken by hunters in the vicinity of kill sites. Hunter-killed female deer were less likely to be infected than males (odds ratios (OR) = 0.2, 95% confidence intervals (CI) = 0.1-0.6; p = 0.015). However, both female (OR = 8.5, 95% CI = 2.3-30.9) and male deer (OR =...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Krumm CE, Conner MM, Hobbs NT, Hunter DO, Miller MW Tags: Biol Lett Source Type: journals

With his memory magnetically erased, a monkey knows he is uncertain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, transcranial magnetic stimulation was used to disrupt cognitive processing by a rhesus monkey (Macaca mulatta) in a computerized divided visual field memory task. When magnetic stimulation disrupted neural activity in the cerebral hemisphere that initially processed the visual images, recognition accuracy declined and use of the uncertain response significantly increased, relative to control conditions. Thus, the monkey tended to respond adaptively when he did not know the answer-where uncertainty was produced by targeted disruption of the neural processing of a stimulus-even in the absence of external, obje...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Washburn DA, Gulledge JP, Beran MJ, Smith JD Tags: Biol Lett Source Type: journals

Ontogeny of long bone geometry in capuchin monkeys (Cebus albifrons and Cebus apella): implications for locomotor development and life history.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we examined the ontogenetic scaling of humeral and femoral cross-sectional robusticity in a mixed-longitudinal sample of two slow-growing, behaviourally altricial capuchin monkeys. Results showed that, when regressed against biomechanically appropriate size variables (i.e. the product of body mass and bone length), humeral and femoral bending strengths generally scale with negative allometry, matching the scaling patterns observed in previous studies of more precocial mammals. Additionally, bone strength relative to predicted loads (e.g. 'safety factors') peaks at birth and rapidly decreases during postnatal...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Young JW, Fernández D, Fleagle JG Tags: Biol Lett Source Type: journals

Three-dimensional resting behaviour of northern elephant seals: drifting like a falling leaf.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During their long migrations through the Pacific, northern elephant seals, Mirounga angustirostris, never haul out on land and they rarely spend more than a few minutes at a time at the surface. They are almost constantly making repetitive, deep dives, raising the question of when do they rest? One type of dive, the drift dive, characterized by a time-depth profile with a phase of lower than average descent speed is believed to be a resting dive. To examine the behaviour of seals during drift dives, we measured body position and three-dimensional diving paths of six juvenile seals. We found that seals rolled over and s...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Mitani Y, Andrews RD, Sato K, Kato A, Naito Y, Costa DP Tags: Biol Lett Source Type: journals

Giant panda conservation science: how far we have come.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The giant panda is a conservation icon, but science has been slow to take up its cause in earnest. In the past decade, researchers have been making up for lost time, as reflected in the flurry of activity reported at the symposium Conservation Science for Giant Pandas and Their Habitat at the 2009 International Congress for Conservation Biology (ICCB) in Beijing. In reports addressing topics ranging from spatial ecology to molecular censusing, from habitat recovery in newly established reserves to earthquake-induced habitat loss, from new insights into factors limiting carrying capacity to the uncertain effects of clim...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Swaisgood RR, Wei F, Wildt DE, Kouba AJ, Zhang Z Tags: Biol Lett Source Type: journals

Visual cues and parental favouritism in a nocturnal bird.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study provides the first experimental evidence of the use of visual cues for parent-offspring communication in a nocturnal bird. PMID: 19864276 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Parejo D, Avilés JM, Rodríguez J Tags: Biol Lett Source Type: journals

Tropical warming and the dynamics of endangered primates.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Many primate species are severely threatened, but little is known about the effects of global warming and the associated intensification of El Niño events on primate populations. Here, we document the influences of the El Niño southern oscillation (ENSO) and hemispheric climatic variability on the population dynamics of four genera of ateline (neotropical, large-bodied) primates. All ateline genera experienced either an immediate or a lagged negative effect of El Niño events. ENSO events were also found to influence primate resource levels through neotropical arboreal phenology. Furthermore, frugivorous ...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Wiederholt R, Post E Tags: Biol Lett Source Type: journals

Individual consistency in flight initiation distances in burrowing owls: a new hypothesis on disturbance-induced habitat selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Individuals often consistently differ in personalities and behaviours that allow them to cope with environmental variation. Flight initiation distance (FID) has been measured in a variety of taxa as an estimate of the risk that an individual is willing to take when facing a predator. FID has been used to test life-history trade-offs related to anti-predatory behaviour and for conservation purposes such as to establish buffer zones to minimize human disturbance, given its species-specific consistency. Individual consistency in FID, however, has been largely overlooked. Here we show that, even after controlling for sever...
Source: Biology Letters - October 28, 2009 Category: Biology Authors: Carrete M, Tella JL Tags: Biol Lett Source Type: journals

Do female ornaments indicate quality in eider ducks?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The fitness consequences of female ornamentation remain little studied and the results are often contradictory. Female ornamentation may be an artefact of a genetic correlation with male ornamentation, but this possibility can be disregarded if the ornament only occurs in females. Female-specific white wing bars in eiders (Somateria mollissima) have been suggested to indicate individual quality, and we studied size variation in this trait in relation to key fitness components and quality attributes. We found that clutch size, body condition, female age, hatching date and success were unrelated to female ornament size; ...
Source: Biology Letters - October 21, 2009 Category: Biology Authors: Lehikoinen A, Jaatinen K, Ost M Tags: Biol Lett Source Type: journals

Inbreeding depression in adaptive plasticity under predation risk in a freshwater snail.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
While much attention has been paid to the effects of inbreeding on fitness, this has mostly come from a genetic perspective. Consequently, the interaction between inbreeding and the environment is less well understood. To understand the effects of inbreeding in natural populations where environmental conditions are variable, we need to examine not only how the effects of inbreeding change among environments but also how inbreeding may affect the ability to respond to environmental conditions (i.e. phenotypic plasticity). We reared selfed and outcrossed hermaphroditic snails (Physa acuta) in the presence and absence of ...
Source: Biology Letters - October 21, 2009 Category: Biology Authors: Auld JR, Relyea RA Tags: Biol Lett Source Type: journals

Phagocytic B cells in a reptile.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Evidence for a developmental relationship between B cells and macrophages has led to the hypothesis that B cells evolved from a phagocytic predecessor. The recent identification of phagocytic IgM+ cells in fishes and amphibians supports this hypothesis, but raises the question of when, evolutionarily, was phagocytic capacity lost in B cells? To address this, leucocytes were isolated from red-eared sliders, Trachemys scripta, incubated with fluorescent beads and analysed using flow cytometry and confocal microscopy. Results indicate that red-eared slider B cells are able to ingest foreign particles and suggest that ecto...
Source: Biology Letters - October 21, 2009 Category: Biology Authors: Zimmerman LM, Vogel LA, Edwards KA, Bowden RM Tags: Biol Lett Source Type: journals

Repeatability of nest morphology in African weaver birds.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is generally assumed that birds build nests according to a genetic 'template', little influenced by learning or memory. One way to confirm the role of genetics in nest building is to assess the repeatability of nest morphology with repeated nest attempts. Solitary weaver birds, which build multiple nests in a single breeding season, are a useful group with which to do this. Here we show that repeatability of nest morphology was low, but significant, in male Southern Masked weaver birds and not significant in the Village weavers. The larger bodied Village weavers built larger nests than did Southern Masked weavers, b...
Source: Biology Letters - October 21, 2009 Category: Biology Authors: Walsh PT, Hansell M, Borello WD, Healy SD Tags: Biol Lett Source Type: journals

Evolution of climate niches in European mammals?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Our ability to predict consequences of climate change is severely impaired by the lack of knowledge on the ability of species to adapt to changing environmental conditions. We used distribution data for 140 mammal species in Europe, together with data on climate, land cover and topography, to derive a statistical description of their realized climate niche. We then compared climate niche overlap of pairs of species, selected on the basis of phylogenetic information. In contrast to expectations, related species were not similar in their climate niche. Rather, even species pairs that had a common ancestor less than 1 Ma ...
Source: Biology Letters - October 13, 2009 Category: Biology Authors: Dormann CF, Gruber B, Winter M, Herrmann D Tags: Biol Lett Source Type: journals

Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carboniferous to end-Permian. Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonu...
Source: Biology Letters - October 13, 2009 Category: Biology Authors: Lamsdell JC, Braddy SJ Tags: Biol Lett Source Type: journals

Food availability differentially influences young males' and females' cognitive processes in accordance with sexual selection theory.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sexual selection theory predicts that additional resources will have a greater impact on males' compared with females' reproductive success. Consequently, we expected that strong cues signalling increased resource availability should augment cognitive functioning associated with long-term maximization of reproductive outcomes (inhibition, working memory) in human males. In human females, who can rely on assistance in resource-rich environments, we expected the opposite effect. We tested this prediction in lower socio-economic status children, since their poverty increased the relative salience of the cues available in ...
Source: Biology Letters - October 13, 2009 Category: Biology Authors: Benenson JF, Rivard R, Markovits H Tags: Biol Lett Source Type: journals

Sperm competition and sperm length influence the rate of mammalian spermatogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sperm competition typically favours an increased investment in testes, because larger testes can produce more sperm to provide a numerical advantage in competition with rival ejaculates. However, interspecific variation in testis size cannot be equated directly with variation in sperm production rate-which is the trait ultimately selected under sperm competition-because there are also differences between species in the proportion of spermatogenic tissue contained within the testis and in the time it takes to produce each sperm. Focusing on the latter source of variation, we provide phylogenetically controlled evidence ...
Source: Biology Letters - October 13, 2009 Category: Biology Authors: Ramm SA, Stockley P Tags: Biol Lett Source Type: journals

Live birth among Iguanian lizards predates Pliocene-Pleistocene glaciations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Among tetrapods, viviparity is estimated to have evolved independently within Squamata (lizards and snakes) more than 100 times, most frequently in species occupying cold climate environments. Because of this relationship with cold climates, it is sometimes assumed that many origins of squamate viviparity occurred over the past 2.5-4 Myr during the Pliocene-Pleistocene glaciations; however, this hypothesis is untested. Divergence-dating analysis on a 733-species tree of Iguanian lizards recovers 20 independent lineages that have evolved viviparity, of which 13 multispecies groups derived live birth prior to glacial adv...
Source: Biology Letters - October 6, 2009 Category: Biology Authors: Schulte JA, Moreno-Roark F Tags: Biol Lett Source Type: journals

Complex vocal imitation during ontogeny in a bat.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report that pups of the bat Saccopteryx bilineata learn a complex vocalization through vocal imitation. During ontogeny, pups of both sexes imitate territorial song from adult males, starting with simple precursor songs that develop into genuine renditions. The resemblance of pup renditions to their acoustic model is not caused by physical maturation effects, is independent of pups' gender and relatedness towards adult males and becomes more pronounced during ontogeny, showing that auditory experience is essential for vocal development. Our findings indicate that the faculty of vocal imitation is more widespread than pr...
Source: Biology Letters - October 6, 2009 Category: Biology Authors: Knörnschild M, Nagy M, Metz M, Mayer F, von Helversen O Tags: Biol Lett Source Type: journals

Ovulation mode modifies paternity monopolization in mammals.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
There are two forms of ovulation: spontaneous and induced. As copulation triggers ovulation for induced ovulators, males can predict the timing of ovulation and may have greater paternity monopolization than spontaneous ovulators. However, this prediction has never, to my knowledge, been tested. Using a cross-species comparison I examined the percentage of offspring sired within a litter (single paternity) and in social species the percentage of offspring sired by the dominant male (alpha paternity). My results indicate that ovulation mode alters the ability of males to monopolize paternity, with males of induced ovula...
Source: Biology Letters - October 6, 2009 Category: Biology Authors: Soulsbury CD Tags: Biol Lett Source Type: journals

Dynamic sexual dichromatism in an explosively breeding Neotropical toad.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sexual selection often promotes the evolution of elaborate colour signals in males, but the importance of sexually selected colour signals remains poorly studied in amphibians. We used reflectance spectrometry to document pronounced sexual dichromatism and dramatic colour change in Bufo luetkenii, a toad that breeds in large aggregations at the onset of the rainy season in Costa Rica. Our observations suggest that males fade rapidly from a vibrant lemon yellow to a dull brown once they have paired with a female. We demonstrate this by showing that males are much brighter than females and that unpaired males are more co...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: Doucet SM, Mennill DJ Tags: Biol Lett Source Type: journals

Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator-prey systems. To solve this, we manipulated the domains of danger of Cape fur seal (Arctocephalus pusillus pusillus) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a propo...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: De Vos A, O'Riain MJ Tags: Biol Lett Source Type: journals

Variation in habitat suitability does not always relate to variation in species' plant functional traits.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Habitat suitability models, which relate species occurrences to environmental variables, are assumed to predict suitable conditions for a given species. If these models are reliable, they should relate to change in plant growth and function. In this paper, we ask the question whether habitat suitability models are able to predict variation in plant functional traits, often assumed to be a good surrogate for a species' overall health and vigour. Using a thorough sampling design, we show a tight link between variation in plant functional traits and habitat suitability for some species, but not for others. Our contrasting...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: Thuiller W, Albert CH, Dubuis A, Randin C, Guisan A Tags: Biol Lett Source Type: journals

Adaptation as organism design.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The problem of adaptation is to explain the apparent design of organisms. Darwin solved this problem with the theory of natural selection. However, population geneticists, whose responsibility it is to formalize evolutionary theory, have long neglected the link between natural selection and organismal design. Here, I review the major historical developments in theory of organismal adaptation, clarifying what adaptation is and what it is not, and I point out future avenues for research. PMID: 19793739 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - September 29, 2009 Category: Biology Authors: Gardner A Tags: Biol Lett Source Type: journals

Whisker isotopic signature depicts migration patterns and multi-year intra- and inter-individual foraging strategies in fur seals.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The movement and dietary history of individuals can be studied using stable isotope records in archival keratinous tissues. Here, we present a chronology of temporally fine-scale data on the trophic niche of otariid seals by measuring the isotopic signature of serially sampled whiskers. Whiskers of male Antarctic fur seals breeding at the Crozet Islands showed synchronous and regular oscillations in both their delta(13)C and delta(15)N values that are likely to represent their annual migrations over the long term (mean 4.8 years). At the population level, male Antarctic fur seals showed substantial variation in both de...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: Cherel Y, Kernaléguen L, Richard P, Guinet G Tags: Biol Lett Source Type: journals

Experience influences aggressive behaviour in the Argentine ant.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
All animals interact with conspecifics during their life, and nearly all also display some form of aggression. An enduring challenge, however, is to understand how the experiences of an individual animal influence its later behaviours. Several studies have shown that prior winning experience increases the probability of initiating fights in later encounters. Using behavioural assays in the laboratory, we provide evidence that, in Argentine ants (Linepithema humile), the mere exposure to an opponent, without the encounter escalating to a fight, also increases the probability that it will display aggression in later enco...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: Van Wilgenburg E, Clémencet J, Tsutsui ND Tags: Biol Lett Source Type: journals

Climate change increases the likelihood of catastrophic avian mortality events during extreme heat waves.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Severe heat waves have occasionally led to catastrophic avian mortality in hot desert environments. Climate change models predict increases in the intensity, frequency and duration of heat waves. A model of avian evaporative water requirements and survival times during the hottest part of day reveals that the predicted increases in maximum air temperatures will result in large fractional increases in water requirements (in small birds, equivalent to 150-200 % of current values), which will severely reduce survival times during extremely hot weather. By the 2080s, desert birds will experience reduced survival times much...
Source: Biology Letters - September 29, 2009 Category: Biology Authors: McKechnie AE, Wolf BO Tags: Biol Lett Source Type: journals

Rapid adaptive evolution of northeastern coyotes via hybridization with wolves.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present mtDNA sequence data from 686 eastern coyotes and measurements of 196 skulls related to their two-front colonization pattern. We find evidence for hybridization with Great Lakes wolves only along the northern front, which is correlated with larger skull size, increased sexual dimorphism and a five times faster colonization rate than the southern front. Northeastern haplotype diversity is low, suggesting that this population was founded by very few females moving across the Saint Lawrence River. This northern front then spread south and west, eventually coming in contact with an expanding front of non-hybrid coyot...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Kays R, Curtis A, Kirchman JJ Tags: Biol Lett Source Type: journals

Exposure to seismic survey alters blue whale acoustic communication.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration da...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Di Iorio L, Clark CW Tags: Biol Lett Source Type: journals

Sometimes the obvious answer is the right one: a response to 'Missing the rarest: is the positive interspecific abundance-distribution relationship a truly general macroecological pattern?'Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19776060 [PubMed - as supplied by publisher] (Source: Biology Letters)
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Blackburn TM, Gaston KJ Tags: Biol Lett Source Type: journals

DNA from a 100-year-old holotype confirms the validity of a potentially extinct hummingbird species.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We used mtDNA sequence data to confirm that the controversial 100-year-old holotype of the Bogotá sunangel (Heliangelus zusii) represents a valid species. We demonstrate that H. zusii is genetically well differentiated from taxa previously hypothesized to have given rise to the specimen via hybridization. Phylogenetic analyses place H. zusii as sister to a clade of mid- to high-elevation Andean species currently placed in the genera Taphrolesbia and Aglaiocercus. Heliangelus zusii, presumed extinct, has never been observed in nature by biologists. We infer that the species occupied a restricted distribution betwee...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Kirchman JJ, Witt CC, McGuire JA, Graves GR Tags: Biol Lett Source Type: journals

Are female monarch butterflies declining in eastern North America? Evidence of a 30-year change in sex ratios at Mexican overwintering sites.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Every autumn the entire eastern North American population of monarch butterflies (Danaus plexippus) undergoes a spectacular migration to overwintering sites in the mountains of central Mexico, where they form massive clusters and can number in the millions. Since their discovery, these sites have been extensively studied, and in many of these studies, monarchs were captured and sexes recorded. In a recent effort to compile the sex ratio data from these published records, a surprising trend was found, which appears to show a gradual decline in proportion of females over time. Sex ratio data from 14 collections of monarc...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Davis AK, Rendón-Salinas E Tags: Biol Lett Source Type: journals

Environmental modulation of metabolic allometry in ornate rainbowfish Rhadinocentrus ornatus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The nature of the relationship between the metabolic rate (MR) and body mass (M) of animals has been the source of controversy for over seven decades, with much of the focus on the value of the scaling exponent b, where MR is proportional to M(b). While it is well known that MR does not generally scale isometrically (i.e. b is seldom equal to 1), the value of b remains the subject of heated debate. In the present study, we examine the influence of an ecologically relevant abiotic variable, pH, on the metabolic allometry of an Australian freshwater fish, Rhadinocentrus ornatus. We show that the value of b is lower for r...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Vaca HF, White CR Tags: Biol Lett Source Type: journals

Meta-analysis in applied ecology.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This overview examines research synthesis in applied ecology and conservation. Vote counting and pooling unweighted averages are widespread despite the superiority of syntheses based on weighted combination of effects. Such analyses allow exploration of methodological uncertainty in addition to consistency of effects across species, space and time, but exploring heterogeneity remains controversial. Meta-analyses are required to generalize in ecology, and to inform evidence-based decision-making, but the more sophisticated statistical techniques and registers of research used in other disciplines must be employed in eco...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Stewart G Tags: Biol Lett Source Type: journals

Group-foraging is not associated with longevity in North American birds.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Group-foraging is common in many animal taxa and is thought to offer protection against predators and greater foraging efficiency. Such benefits may have driven evolutionary transitions from solitary to group-foraging. Greater protection against predators and greater access to resources should reduce extrinsic sources of mortality and thus select for higher longevity according to life-history theory. I assessed the association between group-foraging and longevity in a sample of 421 North American birds. Taking into account known correlates of longevity, such as age at first reproduction and body mass, foraging group si...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Beauchamp G Tags: Biol Lett Source Type: journals

A strain of the bacterial symbiont Regiella insecticola protects aphids against parasitoids.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Aphids commonly harbour facultative bacterial endosymbionts and may benefit from their presence through increased resistance to parasitoids. This has been demonstrated for Hamiltonella defensa and Serratia symbiotica, while a third common endosymbiont, Regiella insecticola, did not provide such protection. However, this symbiont was recently detected in a highly resistant clone of the peach-potato aphid, Myzus persicae, from Australia. To test if resistance was indeed conferred by the endosymbiont, we eliminated it from this clone with antibiotics, and we transferred it to two other clones of the same and one clone of ...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Vorburger C, Gehrer L, Rodriguez P Tags: Biol Lett Source Type: journals

Life history, sexual dimorphism and 'ornamental' feathers in the mesozoic bird Confuciusornis sanctus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The life history of Confuciusornis sanctus is controversial. Recently, the species' body size spectrum was claimed to contradict osteohistological evidence for a rapid, bird-like development. Moreover, sexual size dimorphism was rejected as an explanation for the observed bimodal size distribution since the presence of elongated rectrices, an assumed 'male' trait, was uncorrelated with size. However, this interpretation (i) fails to explain the size spectrum of C. sanctus which is trimodal rather than bimodal, (ii) requires implausible neonate masses and (iii) is not supported by analogy with sexual dimorphisms in mode...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Peters WS, Peters DS Tags: Biol Lett Source Type: journals

Evicting cuckoo nestlings from the nest: a new anti-parasitism behaviour.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
As avian brood parasitism usually reduces hosts' reproductive success, hosts often exhibit strong defence mechanisms. While such host defences at the egg stage (especially egg rejection) have been extensively studied, defence mechanisms at the nestling stage have been reported only recently. We found a previously unknown anti-parasitism behaviour in the large-billed Gerygone, which is a host species of the little bronze-cuckoo, a host-evicting brood parasite. The hosts forcibly pulled resisting nestlings out of their nests and dumped them. Although it has been suggested that defence mechanisms at the nestling stage may...
Source: Biology Letters - September 22, 2009 Category: Biology Authors: Sato NJ, Tokue K, Noske RA, Mikami OK, Ueda K Tags: Biol Lett Source Type: journals

Females prefer to associate with males with longer intromittent organs in mosquitofish.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sexual selection is a major force behind the rapid evolution of male genital morphology among species. Most within-species studies have focused on sexual selection on male genital traits owing to events during or after copulation that increase a male's share of paternity. Very little attention has been given to whether genitalia are visual signals that cause males to vary in their attractiveness to females and are therefore under pre-copulatory sexual selection. Here we show that, on average, female eastern mosquitofish Gambusia holbrooki spent more time in association with males who received only a slight reduction in...
Source: Biology Letters - September 14, 2009 Category: Biology Authors: Kahn AT, Mautz B, Jennions MD Tags: Biol Lett Source Type: journals

Structural equation modelling reveals plant-community drivers of carbon storage in boreal forest ecosystems.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we applied structural equation modelling to a previously published dataset involving 30 boreal-forested islands that vary greatly in their historic fire regime, in order to explore the simultaneous influence of several factors believed to be important in influencing above-ground, below-ground and total ecosystem C accumulation. We found that wildfire was a major driver of ecosystem C sequestration, and exerted direct effects on below-ground C storage (presumably through humus combustion) and indirect effects on both above-ground and below-ground C storage through altering plant-community composition. By cont...
Source: Biology Letters - September 14, 2009 Category: Biology Authors: Jonsson M, Wardle DA Tags: Biol Lett Source Type: journals

Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Killer whales (Orcinus orca) are large predators that occupy the top trophic position in the world's oceans and as such may have important roles in marine ecosystem dynamics. Although the possible top-down effects of killer whale predation on populations of their prey have received much recent attention, little is known of how the abundance of these predators may be limited by bottom-up processes. Here we show, using 25 years of demographic data from two populations of fish-eating killer whales in the northeastern Pacific Ocean, that population trends are driven largely by changes in survival, and that survival rates a...
Source: Biology Letters - September 14, 2009 Category: Biology Authors: Ford JK, Ellis GM, Olesiuk PF, Balcomb KC Tags: Biol Lett Source Type: journals

Rowers' high: behavioural synchrony is correlated with elevated pain thresholds.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Physical exercise is known to stimulate the release of endorphins, creating a mild sense of euphoria that has rewarding properties. Using pain tolerance (a conventional non-invasive assay for endorphin release), we show that synchronized training in a college rowing crew creates a heightened endorphin surge compared with a similar training regime carried out alone. This heightened effect from synchronized activity may explain the sense of euphoria experienced during other social activities (such as laughter, music-making and dancing) that are involved in social bonding in humans and possibly other vertebrates. PMID...
Source: Biology Letters - September 14, 2009 Category: Biology Authors: Cohen EE, Ejsmond-Frey R, Knight N, Dunbar RI Tags: Biol Lett Source Type: journals