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Behavioural Differences (behavioural + difference)
Selected AbstractsNeuroendocrine Function and Chronic Inflammatory StressEXPERIMENTAL PHYSIOLOGY, Issue 5 2002Michael Harbuz The factors regulating susceptibility and severity of autoimmune diseases are poorly understood. That neuroendocrine factors are critical modulators in this regard is self-evident. For example, there are major gender differences in susceptibility with women at greater risk than men of, for example, rheumatoid arthritis (RA) and multiple sclerosis (MS). The hypothalamo-pituitary-adrenal (HPA) axis has rightly attracted a considerable amount of attention. Of particular interest has been the hypothesis that susceptibility to autoimmune disease may be related to an impaired responsiveness of the HPA axis; that is, an inability to mount an appropriate cortisol response with which to down-regulate the immune system might allow the immune system to rampage unchecked and attack self. This hypothesis links regulation of the release from the adrenal gland of the potent anti-inflammatory glucocorticoids to the disease process. Endogenous glucocorticoids are crucial for the regulation of the severity of the disease process. The hypothesis proposing a link between a hyporesponsive HPA axis and susceptibility to disease is compelling. However, evidence from a number of sources has suggested that this may not be the entire story and alterations in the activity of the HPA axis have not been consistently observed in patients with RA. This review will concentrate on recent findings concerning the HPA axis in determining susceptibility to, and in regulating the severity of, inflammatory processes in autoimmune disease. These studies have revealed that a single exposure to endotoxin can confer protection to subsequent development of inflammation in an arthritis model in both neonatal and adult rats. Behavioural differences within a single population of rats are associated with differences in the plasma corticosterone responses to stress. However, relative hyporesponsiveness is not reflected by an increase in the severity of inflammation. In humans with RA the dexamethasone-corticotrophin-releasing factor (CRF) test has revealed two distinct sub-populations of patients. Studies in patients with MS have shown that this is not related to depression but rather to the severity of the disease. A better understanding of these complex neuroendocrine interactions may lead to novel clinical interventions. [source] Behavioural responses to habitat patch boundaries restrict dispersal and generate emigration,patch area relationships in fragmented landscapesJOURNAL OF ANIMAL ECOLOGY, Issue 4 2003Nicolas Schtickzelle Summary 1We studied the consequences of behaviour at habitat patch boundaries on dispersal for the bog fritillary butterfly Proclossiana eunomia Esper in two networks of habitat differing in fragmentation and matrix quality. We tested for differences in responses to patch boundaries according to the fragmentation level of the network by analysing movement paths of adult butterflies. 2Butterflies systematically engaged in U-turns when they reached a boundary in the fragmented network while they crossed over boundaries in more than 40% of boundary encounters in the continuous one. 3We applied the Virtual Migration model (Hanski, Alho & Moilanen 2000) to capture,mark,recapture data collected in both networks. The model indicated (i) a lower dispersal rate and (ii) a lower survival during dispersal in the fragmented network. This latter difference is likely to be the key biological process leading to behavioural avoidance of patch boundary crossings. 4On the basis of this behavioural difference, we designed an individual-based simulation model to explore the relationship between patch area, boundary permeability and emigration rate. 5Predictions of the model fitted observed results of the effect of patch area on emigration rate according to fragmentation: butterflies are more likely to leave small patches than large ones in fragmented landscapes (where patch boundary permeability is low), while this relationship disappears in more continuous landscapes (where patch boundary permeability is high). [source] Genetic life history effects on juvenile survival in bluegillJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2007B. D. NEFF Abstract Foraging behaviour under the risk of predation has important consequences on an individual's survivorship and fitness. In bluegill (Lepomis macrochirus), we have recently shown that offspring sired by males of alternative life histories differ in their foraging behaviour. Specifically, offspring sired by ,cuckolder' males take fewer risks during foraging than do offspring sired by ,parental' males. This behavioural difference can have important consequences on the fitness of the two life histories and thus the underlying evolutionary mechanism. Here, we examine the consequences of this behavioural variation on growth rate, condition and survivorship during early development of juveniles. We used split in vitro fertilization to generate maternal half-sibs that differed in sire life history. The resulting 18 455 larvae from 50 families were released into a microcosm with safe and risky foraging areas for approximately 2 months. A total of 262 juveniles (1.4%) survived of which parentage was unambiguously determined using microsatellite genetic markers for 254 (97%). Although we found significant dam effects, there was no difference in apparent growth rate or condition of juveniles sired by males of the two life histories. Of the 25 paired half-sib families, 15 had higher survivorship when sired by a cuckolder male, seven had higher survivorship when sired by a parental male and three had no surviving offspring from either sire. Thus, although growth was similar between the two offspring types, survivorship was not. Combining the differential survivorship estimate with paternity data from natural nests and the frequency of males adopting each life history, we calculated that the cuckolder life history has 1.87 times higher fitness than the parental life history. As such, the life histories likely are not governed by a genetic polymorphism. [source] Parental care in the whitefly Aleyrodes singularisECOLOGICAL ENTOMOLOGY, Issue 5 2001Moshe Guershon Summary 1. Patches of Aleyrodes singularis nymphs are characterised by a distinctive phenotype composed of the nymphs' exuviae, which are piled on the nymph, and by a covering layer of wax secreted by the adults; these characteristics have been found to confer defensive properties against natural enemies. 2. In contrast to the behaviour typical for ovipositing females of other aleyrodids, A. singularis females tend to remain near the patch of their progeny throughout their development. These mothers were therefore tested to show whether they exhibited active defensive behaviour towards natural enemies, beyond their contribution to passive defence achieved through the secretion of wax on the immatures. 3. The behaviour of whitefly adults differed significantly when performed in the presence of conspecific adults from their behaviour in the presence of natural enemies (either a parasitoid or a predator). The differences were expressed in the mean time devoted to some behavioural events, the frequency at which events were performed, and the number of transitions between pairs of events. 4. Most of the recorded behavioural differences were associated with departure of the natural enemies, facilitating immature survival. 5. This is the first report of active behavioural changes that convey defence of immature offspring for the family Aleyrodidae. Conditions characterising these findings and their relationship with those in which parental care is expected are discussed. [source] Anaesthesia of donkeys and mulesEQUINE VETERINARY EDUCATION, Issue S7 2005N. S. Matthews Summary Great variabilities in the sizes and types of donkeys and mules affects the choice of drugs and anaesthetic management of these equids. Most of the difference between donkeys, mules and horses is apparent when using injectable anaesthetic regimens, since these drugs are distributed and metabolised at rates different from the horse. With inhalant anaesthesia, few differences are seen between equids. However, it is helpful for the clinician to recognise behavioural differences between donkeys, mules and horses which impact on anaesthetic management. [source] Does Lateral Presentation of the Palmate Antlers During Fights by Fallow Deer (Dama dama L.) Signify Dominance or Submission?ETHOLOGY, Issue 5 2002Dómhnall J. Jennings A central aim of the study of animal communication is to identify the mode and content of information transferred between individuals. The lateral presentation of the antler palm between male fallow deer has been described as either a signal of individual quality or an attempt to avoid fighting. In the first case two phenotypic features have been proposed by which transmission of individual quality may be facilitated. These are antler size and antler symmetry. The alternative hypothesis proposes that the lateral presentation of antlers occurs as a consequence of averting a threatening posture and may signify a reluctance to fight. We examined whether mature fallow deer use lateral palm presentation as a display during fights to indicate antler size and symmetry. We found no relationship between presentation rate of the antler and antler size and symmetry. Furthermore, males did not preferentially present their larger antler to their opponent. We also investigated whether the rate at which males presented antlers laterally during a fight was related to their ability to win the fight. Our results show that the male who performed more presentations during a fight was more likely to lose it. There were behavioural differences in the way in which a bout of presentation ended; subsequent losers tended to turn their body away from their opponent and subsequent winners tended to lower their antlers to an opponent which we interpret as an invitation to continue fighting. We conclude that the lateral palm presentation serves to de-escalate fighting between mature fallow deer. It is not a mechanism by which to communicate individual quality but rather an indication that a male is less committed to continuing investment in the current contest. [source] A comparison of different models of stroke on behaviour and brain morphologyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2003C.L.R. Gonzalez Abstract We compared the effects of three models of permanent ischemia, as well as cortical aspiration, on behaviour and brain morphology. Rats received a stroke either by devascularization or by two different procedures of medial cerebral artery occlusion (MCAO; small vs. large). Animals were trained in a reaching task, forepaw asymmetry, forepaw inhibition, sunflower seed task and tongue extension. Behaviour was assessed 1 week after the lesion and at 2-week intervals for a total of 9 weeks. One week after the surgery all animals were severely impaired on all tasks and although they improved over time they only reached preoperative base lines on tongue extension. Animals with small MCAOs performed better in reaching and sunflower tasks; no other behavioural differences were detected among the groups. Pyramidal cells in forelimb and cingulate areas as well as spiny neurons of the striatum were examined for dendritic branching and spine density using a Golgi,Cox procedure. Each lesion type had a different impact on cell morphology. Overall, different changes (atrophy or hypertrophy) were observed with each kind of lesion and these changes were specific for the region (forelimb, cingulate, striatum) and the condition (intact vs. damaged hemisphere). These results suggest that: (i) different lesions to the motor cortex produce subtle differences in behaviour, and (ii) the method used to induce the lesion produces striking differences in cortical and subcortical plasticity. [source] Oral health status in relation to ethnicity of children in the Municipality of Copenhagen, DenmarkINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 3 2003A. Sundby Summary. Approximately 25% of children under the age of 18 in the Municipality of Copenhagen have a non-Danish ethnic background, and it is suspected that there may be major inequalities in oral health as a result. Objectives. The objectives of this study were to describe the occurrence of dental caries in different ethnic minorities, and to analyse whether the dental caries experience of the children may be affected by cultural and behavioural differences. Materials and methods. The study was conducted in Copenhagen as a cross-sectional investigation of 794 children, aged 3 and 5 years old (preschool), 7 years old (Grade 1) and 15 years old (Grade 9). Children of Danish, Turkish, Pakistani, Albanian, Somali and Arabian backgrounds were selected by convenience sampling. Epidemiological data were retrieved from the Danish Recording System for the Public Dental Health Services (SCOR) and sociological data were collected by postal questionnaires. Results. Marked differences in dental caries prevalence were observed when different ethnic minorities were compared to Danish children. These were most prominent for the primary dentition. At age 7, 53% of the Danish and 84% of the Albanian children were affected by dental caries, the mean caries experience was 3·5 dmfs (decayed, missed and filled surfaces) and 13·8 dmfs, respectively. Caries in incisors and/or smooth surfaces was observed in 10% of the Danish children and 48% of the Albanian children. There were cultural differences in dental attendance and self-care practices of children and parents. These socio-behavioural factors may help to explain the differences in dental caries prevalence and severity. Conclusions. Development of appropriate oral health promotion strategies is urgently needed to improve oral health behaviour and attitudes of parents and children of ethnic minorities. Preventive programs should be organized at local community level in close collaboration with key persons of ethnic minority societies. [source] Habitat-specific normal and reverse diel vertical migration in the plankton-feeding basking sharkJOURNAL OF ANIMAL ECOLOGY, Issue 4 2005DAVID W. SIMS Summary 1Megaplanktivores such as filter-feeding sharks and baleen whales are at the apex of a short food chain (phytoplankton,zooplankton,vertebrate) and are sensitive indicators of sea-surface plankton availability. Even though they spend the majority of their time below the surface it is still not known how most of these species utilize vertical habitat and adapt to short-term changes in food availability. 2A key factor likely to control vertical habitat selection by planktivorous sharks is the diel vertical migration (DVM) of zooplankton; however, no study has determined whether specific ocean-habitat type influences their behavioural strategy. Based on the first high-resolution dive data collected for a plankton-feeding fish species we show that DVM patterns of the basking shark Cetorhinus maximus reflect habitat type and zooplankton behaviour. 3In deep, well-stratified waters sharks exhibited normal DVM (dusk ascent,dawn descent) by tracking migrating sound-scattering layers characterized by Calanus and euphausiids. Sharks occupying shallow, inner-shelf areas near thermal fronts conducted reverse DVM (dusk descent,dawn ascent) possibly due to zooplankton predator,prey interactions that resulted in reverse DVM of Calanus. 4These opposite DVM patterns resulted in the probability of daytime-surface sighting differing between these habitats by as much as two orders of magnitude. Ship-borne surveys undertaken at the same time as trackings reflected these behavioural differences. 5The tendency of basking sharks to feed or rest for long periods at the surface has made them vulnerable to harpoon fisheries. Ship-borne and aerial surveys also use surface occurrence to assess distribution and abundance for conservation purposes. Our study indicates that without bias reduction for habitat-specific DVM patterns, current surveys could under- or overestimate shark abundance by at least 10-fold. [source] Surviving glacial ages within the Biotic Gap: phylogeography of the New Zealand cicada Maoricicada campbelliJOURNAL OF BIOGEOGRAPHY, Issue 4 2009Kathy B. R. Hill Abstract Aim, New Zealand is an ideal location in which to investigate the roles of landscape and climate change on speciation and biogeography. An earlier study of the widespread endemic cicada Maoricicada campbelli (Myers) found two phylogeographically distinguishable major clades , northern South Island plus North Island (northern-SI + NI) and Otago. These two clades appeared to have diverged on either side of an area of the South Island known as the Biotic Gap. We sampled more intensively to test competing theories for this divergence. We aimed to discover if M. campbelli had survived within the Biotic Gap during recent glacial maxima, and if predicted areas of secondary contact between the two major clades existed. Location, New Zealand. Methods, We analysed mitochondrial DNA sequences (1520 bp; 212 individuals; 91 populations) using phylogenetic (maximum likelihood, Bayesian), population genetic (analysis of molecular variance) and molecular dating methods (Bayesian relaxed clock with improved priors). Results, We found strong geographical structuring of genetic variation. Our dating analyses suggest that M. campbelli originated 1.83,2.58 Ma, and split into the two major clades 1.45,2.09 Ma. The main subclades in the northern-SI + NI clade arose almost simultaneously at 0.69,1.03 Ma. Most subclades are supported by long internal branches and began to diversify 0.40,0.78 Ma. We found four narrow areas of secondary contact between the two major clades. We also found a difference between calling songs of the Otago vs. northern-SI + NI clades. Main conclusions, Phylogeographical patterns within M. campbelli indicate an early Pleistocene split into two major clades, followed by late Pleistocene range expansion and in situ population differentiation of subclades. The northern-SI + NI clade diversified so rapidly that the main subclade relationships cannot be resolved, and we now have little evidence for a disjunction across the Biotic Gap. Structure within the main subclades indicates rapid divergence after a common bottlenecking event, perhaps attributable to an extremely cold glacial maximum at c. 0.43 Ma. Clade structure and dating analyses indicate that M. campbelli survived in many refugia during recent glacial maxima, including within the Biotic Gap. The narrow overlap between the two major clades is attributed to recent contact during the current interglacial and slow gene diffusion. The two major clades appear to be in the early stages of speciation based on genetic and behavioural differences. [source] Multivariate phenotypes and the potential for alternative phenotypic optima in wall lizard (Podarcis muralis) ventral colour morphsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2010B. CALSBEEK Abstract A major goal in evolutionary biology is to determine how phenotypic variation arises and is maintained in natural populations. Recent studies examining the morphological, physiological and behavioural differences among discrete colour morphotypes (morphs) have revealed several mechanisms that maintain discrete variation within populations, including frequency-dependence, density-dependence and correlational selection. For example, trade-offs over resource allocation to morphological, physiological and behavioural traits can drive correlational selection for morph-specific phenotypic optima. Here, we describe a ventral colour polymorphism in the wall lizard (Podarcis muralis) and test the hypothesis that morphs differ along multivariate axes defined by trade-offs in morphological, physiological, and immunological traits. We show that ventral colour is a discrete trait and that morphs differ in body size, prevalence of infection by parasites and infection intensity. We also find that morphs differ along multivariate phenotypic axes and experience different multivariate selection pressures. Our results suggest that multivariate selection pressures may favour alternative optimal morph-specific phenotypes in P. muralis. [source] Escape behaviour and ultimate causes of specific induced defences in an anuran tadpoleJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2005C. Teplitsky Abstract Induced defences, such as the predator avoidance morphologies in amphibians, result from spatial or temporal variability in predation risk. One important component of this variability should be the difference in hunting strategies between predators. However, little is known about how specific and effective induced defences are to different types of predators. We analysed the impact of both pursuing (fish, Gasterosteus aculeatus) and sit-and-wait (dragonfly, Aeshna cyanea) predators on tadpole (Rana dalmatina) morphology and performance (viz locomotive performance and growth rate). We also investigated the potential benefits of the predator-induced phenotype in the presence of fish predators. Both predators induced deeper tail fins in tadpoles exposed to threat of predation, and stickleback presence also induced longer tails and deeper tail muscles. Morphological and behavioural differences resulted in better escape ability of stickleback-induced tadpoles, leading to improved survival in the face of stickleback predation. These results clearly indicate that specific morphological responses to different types of predators have evolved in R. dalmatina. The specific morphologies suggest low correlations between the traits involved in the defence. Independence of traits allows prey species to fine-tune their response according to current predation risk, so that the benefit of the defence can be maximal. [source] Genetic and morphological differentiation in Tephritis bardanae (Diptera: Tephritidae): evidence for host-race formationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2004T. Diegisser Abstract The fruit fly Tephritis bardanae infests flower heads of two burdock hosts, Arctium tomentosum and A. minus. Observations suggest host-associated mating and behavioural differences at oviposition indicating host-race status. Previously, flies from each host plant were found to differ slightly in allozyme allele frequencies, but these differences could as well be explained by geographical separation of host plants. In the present study, we explicitly test whether genetic and morphological variance among T. bardanae are explained best by host-plant association or by geographical location, and if this pattern is stable over a 10-year period. Populations of A. tomentosum flies differed significantly from those of A. minus flies in (i) allozyme allele frequencies at the loci Pep-A and Pgd, (ii) mtDNA haplotype frequencies and (iii) wing size. In contrast, geographical location had no significant influence on the variance estimates. While it remains uncertain whether morphometric differentiation reflects genotypic variability or phenotypic plasticity, allozyme and mtDNA differentiation is genetically determined. This provides strong evidence for host-race formation in T. bardanae. However, the levels of differentiation are relatively low indicating that the system is in an early stage of divergence. This might be due to a lack of time (i.e. the host shift occurred recently) or due to relatively high gene flow preventing much differentiation at loci not experiencing selection. [source] Lacustrine spatial distribution of landlocked Atlantic salmon populations assessed across generations by multilocus individual assignment and mixed-stock analysesMOLECULAR ECOLOGY, Issue 10 2001C. Potvin Abstract The objective of this study was to assess the spatiotemporal distribution of four landlocked Atlantic salmon (Salmo salar) populations during their sympatric feeding phase in lake St-Jean (Québec, Canada). A total of 1100 fish captured over a period of 25 years was genotyped at six microsatellite loci in order to assess the temporal stability of the relative proportion of each population in different lake sectors using both individual-based assignment and mixed-stock analysis. Estimates of relative proportions obtained from both methods were highly correlated. A nonrandom spatial distribution of populations was observed for each period and, despite the fact that the overall proportion of each population varied over time, the pattern of differential distribution remained generally stable over time. Furthermore, there were indications that the extent of horizontal spatial overlap among populations was negatively correlated with that of their genetic differentiation at both microsatellites and a major histocompatibility complex locus, and independent of the geographical distance between the rivers of origin. We discuss the hypothesis that the temporal stability of spatial distribution, the lack of an association between spatial partitioning and geographical distance between rivers of origin, and the apparent negative correlation between spatial overlap and genetic differentiation, reflect the outcome of selective pressures driving behavioural differences for spatial niche partitioning among populations. [source] Daily patterns of locomotor and sugar-feeding activity of the mosquito Culex annulirostris from geographically isolated populationsPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2005Craig R. Williams Abstract., The daily patterns of locomotor and sugar-feeding activity of virgin female Culex annulirostris from three regions in Australia and a laboratory colony are studied using video techniques in the laboratory. Although all populations display a crepuscular/nocturnal locomotor pattern, significant variation exists between populations, with the pattern of those from southern Australia differing markedly from those in central and northern Australia. It is hypothesized that adaptation of populations to local climates is responsible. Sugar-feeding (inferred from landing on a sugar source) is mostly crepuscular/nocturnal in all populations. The behavioural variation that exists within wide-ranging mosquito species is highlighted, and indicates that significant behavioural differences exist between laboratory colonies and wild-types. [source] Reducing the mortality of freshwater turtles in commercial fish trapsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2005M. B. Lowry Abstract 1.Mortality of air-breathing vertebrates has been recognized for some time as a significant risk in Australian inland fisheries. There has often been conflict between the desires of fishers to maximize catches of their target species and the implementation of effective methods to reduce nontarget bycatch. 2.Two trials were conducted to evaluate the effectiveness of modifications to fish traps designed to prevent the capture of freshwater turtles (Emydura macquarii) and to facilitate their release. The first study evaluated the use of 100 mm exclusion rings to prevent turtles entering eel traps. The second study assessed two configurations of a carp trap designed to release the accidental catch of turtles. 3.Eel traps fitted with 100 mm exclusion rings significantly reduced the turtle bycatch, with no significant difference being observed between mean size of eels captured in traps fitted with exclusion rings and traps without rings. 4.The trials on the modified carp trap confirmed that they effectively retained carp and released a majority (77%) of turtles over a 4 h period. Turtles retained in the carp traps were significantly longer than those that found their way out of the trap. 5.This study demonstrates the different approaches that can be taken to achieve a reduction in non-target bycatch associated with traps, and illustrates the importance of exploiting both the physical and behavioural differences of the target and non-target species in order to develop appropriate gear designs that effectively restrict the entry, or facilitate the release, of bycatch species. Copyright © 2004 John Wiley & Sons, Ltd. [source] Phylogeny, biogeography, and recurrent evolution of divergent bill types in the nectar-stealing flowerpiercers (Thraupini: Diglossa and Diglossopis)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009WILLIAM M. MAUCK III Neotropical tanagers known as flowerpiercers (Diglossa and Diglossopis) have a novel feeding adaptation, comprising a downward curved hook on the maxilla that allows these species to obtain floral nectar without pollination. Using mitochondrial DNA sequences, the phylogenetic relationships of all 18 species of flowerpiercers were studied for the first time. Strong support was found for the monophyly of flowerpiercers and for the monophyly of four superspecies within flowerpiercers. However, previously described species-groups, as well as the genus Diglossopis, are not monophyletic. The biogeographic origin of flowerpiercers was identified as Andean, with a single dispersal event from the northern Andes to Central America and a single dispersal event from the northern Andes to the tepuis. The first principal component, representing a contrast between hook size and bill size, was mapped onto the phylogeny to examine the evolution of relative hook size in the group. Across the phylogeny, a relatively large hook and a relatively small hook evolved multiple times in unrelated lineages, indicating lability in bill morphology. Differences in hook size among sympatric species, together with habitat partitioning and behavioural differences, can explain the coexistence of multiple species of flowerpiercers at the same locality. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 14,28. [source] The evolution of sex pheromones in an ecologically diverse genus of fliesBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009MATTHEW R. E. SYMONDS In theory, pheromones important in specific mate recognition should evolve via large shifts in composition (saltational changes) at speciation events. However, where other mechanisms exist to ensure reproductive isolation, no such selection for rapid divergence is expected. In Bactrocera fruit flies (Diptera: Tephritidae), males produce volatile chemicals to attract females for mating. Bactrocera species exhibit great ecological diversity, with a wide range of geographical locations and host plants used. They also have other mechanisms, including temporal and behavioural differences, which ensure reproductive isolation. Therefore, we predicted that their sex pheromones would not exhibit rapid divergence at speciation events. In the present study, we tested this idea by combining data on male sex pheromone composition for 19 species of Bactrocera with a phylogeny constructed from DNA sequence data. Analyses of the combined data revealed positive correlations between pheromone differences and nucleotide divergence between species, and between the number of pheromone changes along the phylogeny and the branch lengths associated with these changes. These results suggest a gradual rather than saltational mode of evolution. However, remarkable differences in sex pheromones composition exist, even between closely-related species. It appears therefore that the mode of evolution of sex pheromones in Bactrocera is best described by rapid saltational changes associated with speciation, followed by gradual divergence thereafter. Furthermore, species that do not overlap ecologically are just as different pheromonally as species that do. Thus, large changes in pheromone composition appear to be achieved, even in cases where other mechanisms to ensure reproductive isolation exist. We suggest that these differences are closely associated with rapid changes in host plant use, which is a characteristic feature of Bactrocera speciation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 594,603. [source] | |||||||||||||||||||||||||