Female-biased dispersal and patrilocal kin groups in a mammal with resource-defence polygyny

In most mammals, dispersal rates are higher in males than in females. Using behavioural and genetic data of individually marked bats, we show that this general pattern is reversed in the greater sac-winged bat (Saccopteryx bilineata). Dispersal is significantly female biased and male philopatry in combination with rare male immigration causes a patrilineal colony structure. Female dispersal helps avoid father-daughter inbreeding, as male tenure exceeds female age at first breeding in this bat species. Furthermore, our data suggest that females may engage in extra-harem copulations to mate with genetically dissimilar males, and thus avoid their male descendants as mating partners. Acquaintance with the natal colony might facilitate territory takeover since male sac-winged bats queue for harem access. Given the virtual absence of male immigration and the possible lower reproductive success of dispersing males, we argue that enhancing the likelihood of settlement of male descendants could be adaptive despite local mate competition. We conclude that resource defence by males is important in promoting male philopatry, and argue that the potential overlap of male tenure and female first conception is the driving force for females to disperse.     

No evidence of inbreeding avoidance in a polygynous ungulate: the reindeer (Rangifer tarandus)

In polygynous species, mate choice is an integrated part of sexual selection. However, whether mate choice occurs independently of the genetic relatedness among mating pairs has received little attention, although inbreeding may have fitness consequences. We studied whether genetic relatedness influenced females' choice of partner in a highly polygynous ungulate--the reindeer (Rangifer tarandus)--in an experimental herd during two consecutive rutting seasons; the herd consisting of 75 females in 1999 and 74 females in 2000 was exposed to three 4.5-year-old adults and three 1.5-year-old young males, respectively. The females' distribution during peak rut was not influenced by their genetic relatedness with the dominant males of the mating groups. Further, genetic relatedness did not influence the actual choice of mating partner. We conclude that inbreeding avoidance through mating group choice as well as choice of mating partner, two interconnected processes of female mate choice operating at two different scales in space and time, in such a highly female-biased reindeer populations with low level of inbreeding may not occur.     

Dispersal as a means of inbreeding avoidance in a wild bird population

The long-term study of animal populations facilitates detailed analysis of processes otherwise difficult to measure, and whose significance may appear only when a large sample size from many years is available for analysis. For example, inbreeding is a rare event in most natural populations, and therefore many years of data are needed to estimate its effect on fitness. A key behaviour hypothesized to play an important role in avoiding inbreeding is natal dispersal. However, the functional significance of natal dispersal with respect to inbreeding has been much debated but subject to very few empirical tests. We analysed 44 years of data from a wild great tit Parus major population involving over 5000 natal dispersal events within Wytham Woods, UK. Individuals breeding with a relative dispersed over several-fold shorter distances than those outbreeding; within the class of inbreeding birds, increased inbreeding was associated with reduced dispersal distance, for both males and females. This led to a 3.4-fold increase (2.3-5, 95% CI) in the likelihood of close (f=0.25) inbreeding relative to the population average when individuals dispersed less than 200m. In the light of our results, and published evidence showing little support for active inbreeding avoidance in vertebrates, we suggest that dispersal should be considered as a mechanism of prime importance for inbreeding avoidance in wild populations.     

Domestic,peridomestic and wild hosts in the transmission of Trypanosoma cruzi in the Caatinga area colonised by Triatoma brasiliensis

The role played by different mammal species in the maintenance of Trypanosoma cruzi is not constant and varies in time and place. This study aimed to characterise the importance of domestic, wild and peridomestic hosts in the transmission of T. cruzi in Tauá, state of Ceará, Caatinga area, Brazil, with an emphasis on those environments colonised by Triatoma brasiliensis. Direct parasitological examinations were performed on insects and mammals, serologic tests were performed on household and outdoor mammals and multiplex polymerase chain reaction was used on wild mammals. Cytochrome b was used as a food source for wild insects. The serum prevalence in dogs was 38% (20/53), while in pigs it was 6% (2/34). The percentages of the most abundantly infected wild animals were as follows: Thrichomys laurentius 74% (83/112) and Kerodon rupestris 10% (11/112). Of the 749 triatomines collected in the household research, 49.3% (369/749) were positive for T. brasiliensis, while 6.8% were infected with T. cruzi (25/369). In captured animals, T. brasiliensis shares a natural environment with T. laurentius, K. rupestris, Didelphis albiventris, Monodelphis domestica, Galea spixii, Wiedomys pyrrhorhinos, Conepatus semistriatus and Mus musculus. In animals identified via their food source, T. brasiliensis shares a natural environment with G. spixii, K. rupestris, Capra hircus, Gallus gallus, Tropidurus oreadicus and Tupinambis merianae. The high prevalence of T. cruzi in household and peridomiciliar animals reinforces the narrow relationship between the enzootic cycle and humans in environments with T. brasiliensis and characterises it as ubiquitous.     

Chemically induced predator avoidance behaviour in the burrowing bivalve Macoma balthica

The responses of the burrowing bivalves Macoma balthica and Cerastoderma edule to chemical cues emitted by feeding shore crabs Carcinus maenas were investigated. M. balthica held in the laboratory and exposed to chemical signals in effluent water discharging from tanks containing C. maenas fed 20 M. balthica day^− 1 reacted by increasing their burial depths from approximately 30 mm to depths of > 60 mm, over a period of several days. When the signal was removed the bivalves gradually returned to their original depth over 5 days. C. edule similarly exposed to effluent from crabs feeding on conspecifics showed no response. In an attempt to identify the signal inducing this burrowing response, M. balthica were exposed to a variety of chemical signals. Crabs fed M. balthica elicited the strongest response, followed by crabs fed C. edule. There were also small responses to effluent from crabs fed on fish, crabs previously fed on M. balthica and to crab faeces, but no responses to starved crabs, crushed M. balthica, or controls. We conclude that increased burrowing depth of M. balthica is induced by some as yet unidentified chemical cue produced by feeding crabs and is strongest when the crabs were fed on M. balthica. Unexpectedly, neither the presence of crabs themselves, nor of damaged conspecifics, was effective in eliciting a burrowing response. The mortality rates of M. balthica and C. edule selected by crabs when burrowed at normal depths and after exposure to effluent from feeding crabs were different. Crabs selected 1.5 times more C. edule than M. balthica when both species were burrowed at their normal depths, but 15 times more after the tanks had been exposed to effluent from feeding crabs for 5 days. The burrowing response of M. balthica thus appears to reduce mortality significantly by displacing predation pressure on to the more accessible C. edule.     

Population properties affect inbreeding avoidance in moose

Mechanisms reducing inbreeding are thought to have evolved owing to fitness costs of breeding with close relatives. In small and isolated populations, or populations with skewed age- or sex distributions, mate choice becomes limited, and inbreeding avoidance mechanisms ineffective. We used a unique individual-based dataset on moose from a small island in Norway to assess whether inbreeding avoidance was related to population structure and size, expecting inbreeding avoidance to be greater in years with larger populations and even adult sex ratios. The probability that a potential mating event was realized was negatively related to the inbreeding coefficient of the potential offspring, with a stronger relationship in years with a higher proportion or number of males in the population. Thus, adult sex ratio and population size affect the degree of inbreeding avoidance. Consequently, conservation managers should aim for sex ratios that facilitate inbreeding avoidance, especially in small and isolated populations.     

Description of Lentistivalius philippinensis,a new species of flea (Siphonaptera,Pygiosyllomorpha, Stivaliidae), and new records of Ascodipterinae (Streblidae) on bats and other small mammals from Luzon,The Philippines

During May 2009 and July 2011, we collected 357 mammals and examined each for ectoparasites. Among the ectoparasites collected, a new species of flea was discovered. This new species, Lentistivalius philippinensis, is described from the male sex only. Two males were recovered from two specimens of the soricid Crocidura grayi Dobson in Municipality Maria Aurora, Aurora Province, Luzon, Philippines. Additional fleas included Thaumapsylla breviceps orientalis Smit, Thaumapsylla longiforceps Traub, and Ischnopsyllus indicus Jordan. Although the latter species is common in Japan and documented in Guam (as well as mainland Southeast Asia) also on Pipistrellus javanicus (Gray), Ischnopsyllus indicus represents a new record in the Philippine Islands. The ascodipterinae (Streblidae) Maabella stomalata and Ascodipteron speiserianum Muir collected from Rhinolophus inops K. Andersen and Rhinolophus subrufus K. Andersen, respectively, also represent new host records. A key to the species of the flea genus Lentistivalius Traub is provided.     

Interaction between Paracoccidioides brasiliensis conidia and the coagulation system: involvement of fibrinogen

The infectious process starts with an initial contact between pathogenand host. We have previously demonstrated that Paracoccidioidesbrasiliensis conidia interact with plasma proteins includingfibrinogen, which is considered the major component of the coagulation system.In this study, we evaluated the in vitro capacity of P.brasiliensis conidia to aggregate with plasma proteins andcompounds involved in the coagulation system. We assessed the aggregation ofP. brasiliensis conidia after incubation with human serumor plasma in the presence or absence of anticoagulants, extracellular matrix(ECM) proteins, metabolic and protein inhibitors, monosaccharides and othercompounds. Additionally, prothrombin and partial thromboplastin times weredetermined after the interaction of P. brasiliensis conidiawith human plasma. ECM proteins, monosaccharides and human plasma significantlyinduced P. brasiliensis conidial aggregation; however,anticoagulants and metabolic and protein inhibitors diminished the aggregationprocess. The extrinsic coagulation pathway was not affected by the interactionbetween P. brasiliensis conidia and plasma proteins, while theintrinsic pathway was markedly altered. These results indicate that P.brasiliensis conidia interact with proteins involved in thecoagulation system. This interaction may play an important role in the initialinflammatory response, as well as fungal disease progression caused byP. brasiliensis dissemination.     

Living with the enemy: avoidance of hyenas and lions by cheetahs in the Serengeti

Predator avoidance is likely to play a strong role in structuringspecies communities, even where actual mortality due to predationis low. In such systems, mortality may be low because predatoravoidance is effective, and if the threat of predation is liftedthen entire community structures may be altered. Where competitionis intense, then competitor avoidance may have a similar impacton communities. Avoidance behaviors have been documented fora wide range of species, but this is the first attempt to documentavoidance behavior within a large carnivore community. Audioplayback techniques are used to examine the risk perceivedby cheetahs from their two main competitors that are also theirmain predators, lions and hyenas. The results from these experimentsshow that cheetahs actively moved away from lion and hyenaplayback experiments, compared with dummy playbacks where nosound was played. Cheetahs showed no differences in their responsesto playbacks dependent on their sex or reproductive status,suggesting they were responding principally to a competitionrather than a predation threat. However, cheetahs were muchless likely to hunt after competitor playbacks than after dummyplaybacks, and this resulted in a lower kill rate after competitorplaybacks, demonstrating that the perceived presence of competitorshad a noticeable impact on the foraging rate of cheetahs. Furthermore,while cheetahs moved just as far following lion playbacks asafter hyena playbacks, they spent significantly more time lookingat the loudspeaker and were less likely to make a kill afterlion playbacks, suggesting that cheetahs perceive lions tobe a greater threat than hyenas.     

Involvement of cotton gene GhFPF1 in the regulation of shade avoidance responses in Arabidopsis thaliana

Phytochrome system perceives the reduction in the ratio of red to far-red light when plants are grown under dense canopy. This signal, regarded as a warning of competition, will trigger a series of phenotypic changes to avoid shade. Progress has been made for several phytochrome signaling intermediates acting as positive regulators of accelerated elongation growth and promotion of flowering in shade-avoidance has been identified. Recently, a FPF1 homolog GhFPF1 was identified in upland cotton. Our data supported that transgenic Arabidopsis of over-expressing GhFPF1 displayed a constitutive shade-avoiding phenotype resembling phyB mutants in several respects such as accelerated elongation of hypocotyl and petioles, upward of leaf movement, and promoted flowering. In this addendum, by dissection of GhFPF1 acting as a component of shade-avoidance responses we suppose that GhFPF1 might influence the timing of the floral transition independently of shade-mediated early flowering. Furthermore, the opposite changes of IAA content in transgenic leaves and stems suggested that alteration of IAA storage and release took place during shade-avoidance responses.     

Why do shrews twitter? Communication or simple echo-based orientation

Shrews are very vocal animals. We tested behaviourally whether the high-pitched laryngeal ‘twittering’ calls of as-yet unclear function serve for communication or echo-based orientation. We used a representative species from each of the two largest phylogenetic groups of shrews. In both species, experimental manipulation of substrate density, but not of the likelihood of conspecific presence, affected the shrews'' call rate when exploring an unknown environment. This adaptation of call rate to the degree of habitat clutter parallels bat echolocation and suggests that shrews may use the echoes and reverberations of their calls for identifying routes through their habitat or for probing habitat type. To assess the acoustic feasibility of shrew echo orientation, we ensonified shrew habitats in the field with an ‘artificial shrew’ (small speaker mounted close to a sensitive microphone). The data showed that shrew-like calls can indeed yield echo scenes useful for habitat assessment at close range, but beyond the range of the shrews'' vibrissae.     

Rapid evolution of Wolbachia incompatibility types

In most insects, the endosymbiont Wolbachia induces cytoplasmic incompatibility (CI), an embryonic mortality observed when infected males mate either with uninfected females or with females infected by an incompatible Wolbachia strain. Although the molecular mechanism of CI remains elusive, it is classically viewed as a modification–rescue model, in which a Wolbachia mod function disables the reproductive success of the sperm of infected males, unless eggs are infected and express a compatible resc function. The extent to which the modification–rescue model can predict highly complex CI pattern remains a challenging issue. Here, we show the rapid evolution of the mod–resc system in the Culex pipiens mosquito. We have surveyed four incompatible laboratory isofemale lines over 50 generations and observed in two of them that CI has evolved from complete to partial incompatibility (i.e. the production of a mixture of compatible and incompatible clutches). Emergence of the new CI types depends only on Wolbachia determinants and can be simply explained by the gain of new resc functions. Evolution of CI types in Cx. pipiens thus appears as a gradual process, in which one or several resc functions can coexist in the same individual host in addition to the ones involved in the self-compatibility. Our data identified CI as a very dynamic process. We suggest that ancestral and mutant Wolbachia expressing distinct resc functions can co-infect individual hosts, opening the possibility for the mod functions to evolve subsequently. This gives a first clue towards the understanding of how Wolbachia reached highly complex CI pattern in host populations.