Female-biased natal and breeding dispersal in an alpine lizard, Niveoscincus microlepidotus

We measured two aspects of dispersal in the alpine Australian scincid lizard, Niveoscincus micolepidotus : (1) natal dispersal, i.e. shift in home range over the lizard's first year of life, and (2) breeding dispersal, i.e. shifts of home ranges between breeding attempts as adults. On average, displacements were surprisingly small. Female neonates dispersed about twice as far as did males in the same cohort (means of 12 m vs. 6 m). A female's natal dispersal distance was not correlated with her body size or our estimate of physiological performance (sprint speed). However, larger, faster-running male neonates dispersed further than did smaller, slower males. As was the case for neonates, adult females moved significantly further between breeding seasons than did adult males (14.2 m vs. 9.6 m). Because of a female's long gestation period (more than 1 year), two groups of females occur simultaneously in the population, non-ovulated (i.e. with yolking folicles) and pregnant females (i.e. approaching parturition). Females that were not yet ovulated showed a markedly stronger dispersal in response to high reproductive effort (i.e. clutch size in relation to body condition) than did pregnant females. In adult males, body size was negatively correlated with dispersal distance, suggesting that although males have overlapping territories, they exhibit an increasing level of site tenacity with age and/or size. Thus, selection for the relatively more pronounced site tenacity in adult males may have resulted in the more marked philopatric behaviour compared to females also as neonates.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 277–283.     

Influence of hatching asynchrony and within-brood parental investment on size, condition, and immunocompetence in nestling red-billed choughs

Studies of hatching asynchrony have rarely assessed the effect of parental investment strategies on the development of intra-brood hierarchies using indicators of nestling quality. The influence of hatching asynchrony and other variables related to parental investment on immunocompetence was evaluated measuring T-cell mediated immune response in broods of red-billed choughs ( Pyrrhocorax pyrrhocorax ), a large long-living passerine with a pronounced sexual size dimorphism. The results showed that T-cell mediated immune response depends on parental effects as shown by the differences between broods on hatching asynchrony. Male nestlings were both heavier and larger than female nestlings, but there was no effect of hatching order on these traits, nor on sex differences in immunocompetence. Differential investment strategy in relation to laying order did not favour older offspring or either of the sexes. Successful reproduction in this species might be so unpredictable and infrequent that strategies of parental investment in the brood could have evolved to attempt to maximize the survival of all nestlings by avoiding within-brood hierachies of size, body condition, and immunocompetence.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 675–684.     

Adaptive coat colour polymorphism in the Kermode bear of coastal British Columbia

We investigated potential ecological attributes of the striking coat colour polymorphism in the black bear ( Ursus americanus kermodei Hornaday) occurring on several small islands off the mid-coast of British Columbia, where a white morph (Kermode), fully recessive to the black morph, reaches 10–25% of the population. During three autumn field seasons (2000–2002; 697 h of observation time), we monitored salmon capture behaviour of individual bears (black, N  = 37; white, N  = 4). Both colour morphs foraged on salmon throughout daylight and darkness but with twice the rate during darkness. Log-linear analysis of capture efficiency (success/attempts) and average capture success per bout of the white morph was marginally lower than the black morph during darkness (22.8%, N  = 158 versus 25.8%, N  = 279 respectively; P  < 0.04), although it was significantly higher during daylight (34.1%, N  = 132 versus 25.3%, N  = 896, respectively, P  < 0.02), with similar trends in three different pursuit modes. Replicated ( N  = 10–14) field experiments involving a colour dimorphic simulated predator (i.e. human in a black or white cloak) showed that salmon were one-half as evasive during darkness than during daylight, with no differences ( P  > 0.4) in response to either the white or black models; however, during daylight, salmon were twice as evasive to the black compared to the white model ( P  < 0.001). The persistence of this coat colour polymorphism may be facilitated by increased salmon accessibility to the Kermode bear and diel foraging differences between morphs. These results are consistent with multi-niche models of adaptive variability.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 479–488.     

Reproductive performance of otters Lutra lutra (Linnaeus, 1758) in Eastern Germany: low reproduction in a long-term strategy

The reproductive status of female otters ( Lutra lutra ) was determined from an examination of 518 carcasses collected from Eastern Germany between 1950 and 2001. In Germany otters mate throughout the year. Significant seasonal differences are evident with a distinct peak in summer. Females were in breeding condition between the ages of three and 15 years, with the majority between six and nine years. The mean litter size at birth was 2.36, which was the lowest when compared with other inland populations. There were no significant differences in litter size for regions, seasons or age. Prenatal losses account for 26.31%. The mortality between birth and first appearance of cubs following their mother is about 29%. An effective reproduction rate of 78.4% was deduced from the known age structure of the sample and the proportion of breeding females. Reproductively active females show a significantly higher body condition than non-reproductive females. Following these investigations into breeding status, suggestions on reproductive output and the life history of the otter are discussed.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 329–340.     

Condition-dependent spermatophore size is correlated with male's age in a bushcricket (Orthoptera: Phaneropteridae)

During mating, male bushcrickets transfer a spermatophore that consists of a sperm-containing ampulla and a product of the accessory glands, the spermatophylax, which females directly ingest. In the present study, we demonstrate male spermatophore allocation in the bushcricket Poecilimon zimmeri . Males of this species show condition-dependent spermatophore investment. This investment depended upon the age at first mating of males, with older individuals transferring larger spermatophores than younger ones of the same body mass. Independently of age, heavier males transfer larger spermatophores, but the size of males (as measured by femur length) was not a good predictor. Heavier males allocate a lower proportion of their mass to spermatophores and reach their maximal investment point earlier than less heavy males. Spermatophylax production levelled off to a species specific maximum earlier than that of sperm investment (measured as ampulla mass), suggesting that males face high levels of sperm competition.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 354–360.     

Using image analysis on the ventral colour pattern in Salamandrina perspicillata (Amphibia: Salamandridae) to discriminate among populations

The ventral colour pattern in Salamandrina perspicillata is characteristic of each individual and remains invariant throughout the salamanders' life. The present study aimed to determine, using statistical methods applied to quantitative image analysis, whether the coloration pattern is population-specific. The images of ventral colour pattern of 180 salamanders belonging to five populations were analysed. The images were previously warped by geometric morphometry. To our knowledge, this is the first study to use an approach based on geometric morphometrics to standardize ventral shapes. This technique is useful for eliminating form distortions. The results of an analysis of similarities recognized more coloration similarity among individuals of the same population than among individuals from different populations. Analysis by partial least squares correctly classified the 88.88% of individuals into the correct population. The similarities or differences among individuals of different populations are not related to the geographical distances. The results obtained showed that the coloration of the ventral side of the head of the salamanders can be used for discriminating among populations.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 35–43.     

Frequency of fault bars in feathers of birds and susceptibility to predation

Fault bars are transparent bands in the feathers of birds produced under stressful and adverse conditions. The frequency of feathers with fault bars is highly heterogeneous among species. We predicted that prey had a higher frequency of fault bars than individuals from the general population, and that a high susceptibility to predation would be associated with a low frequency of fault bars among species of birds because such species would suffer particularly high costs of producing fault bars. The frequency of fault bars in prey was almost three-fold higher than in the general population, based on a database on the frequency of fault bars and susceptibility to predation by the goshawk Accipiter gentilis L., implying intense natural selection against fault bars. A high susceptibility to predation by the sparrowhawk Accipiter nisus L. and the goshawk, relative to what would be expected from their abundance, was associated with a low frequency of fault bars across species, with long distance migration also being negatively associated with frequency of fault bars. Feathers with fault bars were more likely to break than feathers without fault bars, thereby potentially affecting the flight ability of individuals. These findings are consistent with the hypothesis that susceptibility to factors that cause production of fault bars can be modified by natural selection, as illustrated by the impact of predation on the frequency of fault bars.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 334–345.     

Costs of carnivory: tooth fracture in Pleistocene and Recent carnivorans

Large, carnivorous mammals often break their teeth, probably as a result of tooth to bone contact that occurs when carcasses are consumed more fully, a behaviour likely to occur under conditions of food stress. Recent studies of Pleistocene predators revealed high numbers of teeth broken in life, suggesting that carcass utilization and, consequently, food competition was more intense in the past than at present. However, the putative association between diet and tooth fracture frequency was based on a small sample of large, highly carnivorous species. In the present study, a greater diversity of extant carnivorans is sampled, including insectivorous, omnivorous, and carnivorous forms, ranging in size from weasels to tigers. Species that habitually consume hard foods (bones, shells) had the highest fracture frequencies, followed by carnivores, and then insectivorous and/or omnivorous species. Predator and prey sizes were not associated with tooth fracture frequency, but more aggressive species did break their teeth more often. Comparison of the modern sample with five Pleistocene species confirms the previous finding of higher tooth breakage in the past, although some extant species have fracture frequencies that approach those of extinct species. Thus, the Pleistocene predator guild appears to have been characterized by relatively high levels of competition that are rarely observed today.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 68–81.     

Population genetics of the black ant Formica lemani (Hymenoptera: Formicidae)

Colony kin structure and spatial population structure were studied in multiple populations of the ant Formica lemani , using allozymes and DNA microsatellites. Average genetic relatedness between nestmate workers varied little between populations ( r  = 0.51–0.76), indicating that the average colony kin structure was relatively simple. Worker genotypes could not be explained with a single breeding pair in all nests, however, and the distribution of relatedness estimates across nests was bimodal, suggesting that single- and multi-queen colonies co-occur. We studied spatial population structure in a successional boreal forest system, which is a mixture of different aged habitats. Newly clear-cut open habitat patches are quickly colonized by F. lemani , where it is able to persist for a limited number of generations. Newly-founded populations showed signs of a founder effect and spatial substructuring, whereas older populations were more homogenous. This suggests that new populations are founded by a limited number of colonizers arriving from more than one source. Genetic differentiation among local populations was minor, indicating strong migration between them. There were, however, indications of both isolation by distance and populations becoming more isolated as habitat patches grew older.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 247–258.     

Changes in sperm stores, ejaculate size, fertilization success, and sexual motivation over repeated matings in the common toad, Bufo bufo (Anura: Bufonidae)

Fertilization is of central importance in the determination of reproductive success for both males and females. In species where males have the chance to mate repeatedly within a short period of time, sperm stocks may become depleted and males may have to carefully economize on their sperm reserves. Also, intensive intrasexual competition for females and repeated matings may lead to exhaustion on the behavioural level. To determine whether the reproductive potential of males is limited and if such a limitation is due to behavioural exhaustion or sperm depletion, we experimentally investigated changes in sperm stores, sperm expenditure, fertilization success, and sexual motivation over three repeated matings in the common toad, Bufo bufo , where the breeding season is short and sequential polygyny occurs. At the end of the breeding season, the number of sperm stored in the testes of males mated repeatedly was close to 50% lower than in testes of unmated males. Ejaculate size, which was estimated by applying a novel method allowing direct quantification, decreased by 88% from first to third matings. We also observed a drop in fertilization success from the first two to third matings by 65%, which was largest in males that had started the reproductive season in bad body condition. Some of these males also showed a decreased interest in females in the third mating round. Our results suggest that sperm depletion and loss of sexual motivation may together set a limit to the reproductive potential of common toad males. The present study draws attention to a limitation in reproductive potential, which may occur more often than currently anticipated and has the potential to strongly influence several aspects of reproductive behaviour.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 361–371.     

Who's your daddy? Paternity testing reveals promiscuity and multiple paternity in the carnivorous marsupial Dasyurus maculatus (Marsupialia: Dasyuridae)

Female promiscuity is common among mammals but its advantages, particularly for marsupials, remain unclear. Using microsatellite DNA from pouch young of known mothers, we identified the most likely fathers of 25 wild spotted-tailed quolls ( Dasyurus maculatus ) from six litters. We aimed to determine whether young within the same litter had different fathers, and whether breeding success of males was associated with large body mass (consistent with inter-male competition) or scrotal width (consistent with sperm competition). We also explored the possible influence of promiscuity on relatedness within litters. Finally, we used data on paternity and relatedness to make inferences regarding movement and dispersal.
Four litters were sired by more than one male, and three males sired offspring in more than one litter. Known fathers had higher body mass, but not scrotal width, than males of unknown paternity status, suggesting that males may compete for access to females. Sires were less related to dams than expected by chance, and litters with multiple paternity had lower relatedness than litters sired by a single male.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 1–7.     

Effects of habitat heterogeneity and local adaptation on the body condition of a forest passerine at the edge of its distributional range

We studied fluctuating asymmetry and feather growth rates as indicators of fitness of blackcaps ( Sylvia atricapilla ) breeding at the border of their distribution range in the Iberian Peninsula. Iberian blackcaps increase their abundance with increasing rainfall and ground cover of brambles. In border habitats, they are sedentary and morphologically different from migrants, suggesting that they could be adapted to peripheral conditions. We tested whether juvenile body condition depends on (1) distance from the centre of the range, (2) mean precipitation or (3) bramble cover. Controlling for environmental variation, we tested for differences between migratory and sedentary populations. Body condition varied across the Iberian gradient in parallel with changes in precipitation. Controlling for this effect, sedentary populations were in better body condition than migratory populations. Our results support the idea that environmental heterogeneity causes fitness to fluctuate across species' ranges, and also that local adaptation may mean that peripheral populations are more than a 'tail end' of the species.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 479–488.     

Offspring performance is linked to parental identity and male breeding ornamentation in whitefish

The 'good genes' hypothesis predicts that males advertise their quality with different sexual ornaments and that females are able to recognize the genetic quality of males by evaluating these characteristics. In the present study, we investigated the parental effects on offspring performance (feeding and swimming ability of newly-hatched larvae) and examined whether male ornamentation indicates offspring success in performance trials of whitefish ( Coregonus lavaretus Linnaeus). Offspring first-feeding success had a strong paternal effect and it was also positively correlated with the size of male breeding tubercles, indicating that breeding ornamentation of males can function as an honest indicator of their genetic quality. In addition, the observed positive correlation between male tubercle size and condition factor suggests that highly ornamented males are efficient foragers and that this trait may have a heritable basis. By contrast to feeding success, only a maternal effect was found in the swimming ability of the larvae. Clear family-specific differences observed in both measures of performance strongly suggest that parental identity may have important effects on larval survival in the wild.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 532–539.     

Low population genetic structuring of two cryptic bat species suggests their migratory behaviour in continental Europe

Although two cryptic pipistrelle bat species, Pipistrellus pipistrellus and Pipistrellus pygmaeus , belong among the most common bat species in Europe, it is still unclear whether they can migrate over long distances between summer and winter roosts. Long-distance migratory species may be expected to show low levels of genetic structuring in large areas due to regular mixing of the gene pool by mating that occurs during migration and/or hibernation. Conversely, the dispersal of gametes in sedentary species is spatially restricted, populations are more genetically structured, and isolation by relatively short distance is visible. By analysing diversity of highly variable microsatellites within and among summer colonies of both studied species in central Europe, we found that differentiation between populations is very weak. Both classical F _ST and Bayesian clustering approach failed to detect genetic structure among colonies and there was no significant isolation-by-distance pattern. The analyses of relatedness, however, revealed that individuals within colonies are more related than random suggesting philopatry of at least one sex. The results were very similar for the two species. The high level of gene flow among central European populations, even on large geographic distances, is discussed in relation with migrations, dispersal, and mating behaviour.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 103–114.     

Correlates of timing of spring migration in birds: a comparative study of trans-Saharan migrants

The evolution of migratory strategies in birds is likely to have been influenced by ecological as well as socio-sexual factors in both wintering and breeding areas. In this comparative study, we analysed timing of spring passage of 38 long-distance migratory bird species that winter south of the Sahara desert and breed in Europe, in relation to wintering and breeding latitudes, moult strategy, nesting site (open vs. cavity), and sexual dimorphism in size and coloration, which may reflect intensity of sexual selection. We employed a large data set consisting of more than 190 000 individuals ringed during spring migration in the Mediterranean Sea. We found that the species that migrated earlier were those wintering farther north, nesting in cavities and showing the largest degree of sexual size dimorphism (SSD). However, sexual dichromatism was not related to migration date. Among passerine species, moulting wing-feathers in Africa delayed migration. We found no support for the energetic constraint hypothesis, which proposes that early arrival selects for large male size, since early arriving species were not larger than late arriving ones. Thus, the observed associations suggest that variation in migration schedules at the interspecific level may have evolved in relation to ecological factors and SSD, possibly reflecting the intensity of mating competition.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 199–210.     

Variation in social rank acquisition influences lifetime reproductive success in black-capped chickadees

Dominance relationships structure many animal societies, yet the process of rank attainment is poorly understood. We investigated acquisition of social dominance in winter flocks and its fitness consequences in male black-capped chickadees (Poecile atricapillus) over a 10-year period. Age was the best predictor of rank, and paired comparisons showed high-ranked males to be older than their low-ranked flock-mates. When controlling for age, morphological variables did not predict male social rank, but high-ranked males were heavier, had lower fat scores and were in leaner condition than low-ranked males. Males that survived between years tended to increase in rank over time; however, the rate of rank advancement varied individually. Rank reversals between familiar contestants were rare, and changes in male social rank were associated with changes in flock membership. Average lifetime reproductive success (LRS) of males and females was variable and best predicted by lifespan. Male rank history also influenced realized reproductive success. Birds with higher average rank over their lifespan were more likely to reproduce successfully. However, among successful birds, average rank did not significantly predict LRS. Thus, birds that lived longer and attained high social rank earlier had higher fitness, but this effect was not manifested as fine-scale differences among successful individuals. Taken together, these findings demonstrate the importance of social factors influencing individual fitness.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 85–95.     

Growth and the expression of alternative life cycles in the salamander Ambystoma talpoideum (Caudata: Ambystomatidae)

Complex life cycles (CLCs) contain larval and adult phases that are morphologically and ecologically distinct. Simple life cycles (SLCs) have evolved from CLCs repeatedly in a wide variety of lineages but the processes that may underlie the transition have rarely been identified or investigated experimentally. We examined the influence of larval growth rate on the facultative expression of alternative life cycles (metamorphosis or maturation as gill-bearing adults [= paedomorphosis]) in the salamander Ambystoma talpoideum. We manipulated growth rates by altering the amount of food individuals received throughout larval development. The expression of alternative life cycles in A. talpoideum is influenced by growth via food levels, but the same growth rates at different points in the larval period elicit different responses. Individuals were more likely to metamorphose (i.e. express a CLC) when food levels and growth rates were high later in development and more likely to mature without metamorphosing (SLC) when growth rates were comparatively low during the same point in development. Growth rates at particular points in development, rather than overall larval growth rate, may be an important proximate factor in salamander life-cycle evolution.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 639–646.     

Odour–genes covariance within a natural population of subterranean Spalax galili blind mole rats

Previous research, using habituation techniques with multiple rodent species as subjects, has demonstrated (from kin to across species) the greater perceptual similarity in the qualities of individual odours of more closely genetically related individuals ('odour–genes covariance', abbreviated 'OGC'). This predictable relationship between individual genotypes and individual odours has only been assessed in rodents in which the genetic similarities and dissimilarities are known either through laboratory breeding or by selecting odour donors from different populations or species. To study OGC within a natural population of rodents, we genotyped Spalax galili blind mole rats using ten microsatellite markers, and conducted pairwise genetic distance comparisons to estimate genetic similarity and to calculate the relatedness coefficient between pairs of individuals. We then used habituation-generalization techniques to assess whether perceived odour similarities covaried with the genetic similarities we had identified. Indeed, animals treated odours from genetically closer donors as more similar than odours from less genetically similar donors. The results suggest an accurate and subtle ability to resolve genetically determined odour distinctions among familially unrelated animals within a population. Graded differential responses to conspecific odours based on degrees of similarity between other individuals' odours and one's own have been demonstrated in kinship and species discriminations and preferences. The evidence presented here provides the basis for hypothesizing a similar process that could promote optimal outbreeding and inclusive fitness within populations of conspecifics. The evolutionary implications of these findings are discussed.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 483–490.     

Laying date,body mass and tick infestation of nestling tropical Roseate Terns Sterna dougallii predict fledging success,first‐year survival and age at first return to the natal colony

Both intrinsic and extrinsic factors recorded at individual nests can predict offspring fitness and survival but few studies have examined these effects in the tropics. We recorded nestling survival, post‐fledging survival and age at first return of Roseate Terns breeding at Aride Island, Seychelles, over a 12‐year period (1998–2009). Nest data recorded at the egg, nestling and fledging stages were collected during six breeding seasons (1998, 2001–2005) and a capture‐mark‐recapture dataset of six cohorts of fledglings was obtained from 2001–2009. Logistic regression models were used to assess the predictive effect of reproductive variables on fledging success, while multistate capture‐mark‐recapture models were used to estimate post‐fledging survival and return–recruitment probabilities to the natal site. Nestling survival probability increased with earliness of laying and was negatively affected by tick infestation during the growth period (0–23 days). Fledging probability was also positively related to chick body condition, whereas other pre‐fledging reproductive parameters such as clutch size and egg size were not influential. A multistate modelling of age‐specific survival and return–recruitment (transition) rates found that first‐year survival differed between cohorts and was also negatively affected by tick infestation. Annual survival stabilized from age 2 onwards at 0.83 ± 0.02. Transition rates were positively related to body condition at fledging, with heavier individuals returning for the first time to the natal colony at a younger age compared with lighter individuals. These results highlight the importance of local conditions encountered by tropical seabirds during the breeding season in shaping demographic parameters.     

Morphology, growth and reproduction in the Australian house mouse: differential effects of moderate temperatures

The house mouse ( Mus musculus domesticus ) was introduced into Australia two centuries ago and is now succeeding in a wide range of habitats and climatic regions. To explore how mice exploit such extreme environments, we compared growth rate, morphology and reproductive success of animals reared under differing thermal regimes (13 °C 'cool', 22 °C 'moderate' and 30 °C 'warm') in laboratory mice derived from wild stock. 'Warm' group young were smaller and grew more slowly than those from other groups. At 6 weeks of age, body mass was less in 'warm' than in 'cool' treatment individuals; and liver mass/body mass also was less in 'warm' than in 'cool' treatment individuals. Paired kidney mass/body mass and paired adrenal mass/body mass were less in 'warm' than in 'cool' and 'moderate' treatment mice. Low heritability values indicate that these effects were from the temperature treatments rather than genetic influences. Irrespective of temperature treatment, females were more likely to produce a litter from post-partum matings if they were experienced, rather than young or reproductively naïve, and also bore more young from post-partum matings. These observations contribute to understanding of the sudden plague activities of mice in some parts of Australia and also their sparse distribution in the interior of the continent.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 21–30.