A dynamic population model for tsetse (Diptera: Glossinidae) area-wide integrated pest management

A spatial model of tsetse (Glossina palpalis ssp. and G. pallidipes) life cycle was created in FORTRAN, and four control measures [aerial spraying of non-residual insecticides, traps and targets, insecticide-treated livestock (ITL) and the sterile insect technique] were programmed into the model to assess how much of each of various combinations of these control tactics would be necessary to eradicate the population. The model included density-independent and -dependent mortality rates, temperature-dependent mortality, an age-dependent mortality, two mechanisms of dispersal and a component of aggregation. Sensitivity analyses assessed the importance of various life history features and indicated that female fertility and factors affecting survivorship had the greatest impact on the equilibrium of the female population. The female equilibrium was likewise reduced when dispersal and aggregation were acting together. Sensitivity analyses showed that basic female survivorship, age-dependent and temperature-dependent survivorship of adults, teneral-specific survivorship, daily female fertility, and mean temperature had the greatest effect on the four applied control measures. Time to eradication was reduced by initial knockdown of the population and due to the synergism of certain combinations of methods [e.g., traps-targets and sterile insect technique (SIT); ITL and SIT]. Competitive ability of the sterile males was an important parameter when sterile to wild male overflooding ratios were small. An aggregated wild population reduced the efficiency of the SIT, but increased it with increased dispersal. The model can be used interactively to facilitate decision making during the planning and implementation of operational area-wide integrated pest management programs against tsetse.     

Tsetse: the limits to population growth

Growth rates of tsetse populations were estimated by calculating the dominant eigenvalues of appropriate Leslie matrices. The individual effects of four variables (pre-adult and adult survival probability, interlarval period and pupal duration), have been investigated by varying each one over a wide range of values, while the other three are held constant. R, the log of the growth rate, was found to vary approximately linearly with adult and pre-adult death rate; a 1% change in the adult death rate causes approximately a 10-fold change in R. R varies linearly with the log of fecundity and of the pupal duration. An increase in the pupal duration results in a decrease in the growth rate for populations which have a positive growth rate, but an increase for populations which have a negative growth rate. For a population at equilibrium, a change in the pupal duration has no effect. Small changes in fecundity have less effect on the growth rate than small changes in the death rate; this fact is advanced as an important contributor to the generally very cautious nature of female tsetse, and their aversion to man, particularly as a potential host. A simple linear model is described which relates R to all four variables and their first order interactions. The model is used to produce a set of graphs which encapsulate the relationship between the growth rate and the vital parameters over a wide range of values. It is also used to draw the loci on one side of which tsetse populations grow, and on the other of which they decline. Population resilience is discussed in relation to the problem of tsetse eradication; it is concluded that if one can impose and sustain an added mortality of 4% per day on any female tsetse population then it must go extinct, regardless of the strength of the density dependent processes; and it seems likely that in most field conditions only an added 2-3% is required. It is pointed out that ground and aerial spraying techniques produce much higher daily mortalities than this, but they may often not be sustained for sufficiently long to achieve eradication. When odour-baited targets are used the increased death rate is much smaller, but it can be sustained as required; recent work in Zimbabwe shows that there is a good correspondence between the calculated imposed death rate and the observed rate of decline of tsetse populations.     

MATING PREFERENCE AND ITS RELEVANCE TO ADAPTATION IN DROSOPHILA MELANOGASTER: INVERSION POLYMORPHISM AND DDT RESISTANCE

The importance of adult mating success as a component of fitness influencing inversion polymorphism in two DDT-resistant populations of Drosophila melanogaster was investigated. The polymorphism involved In(3R)P and the Standard (St) gene arrangement. In population 731R the St/St females showed greater mating propensity than In/In females, while in population J2 the In/In females showed a significant positive association between mating propensity and the percentage of St/St males present. Mating preference data showed that St/St males were selectively favored over In/In males in both populations. No differences were observed between St/St and St/In karyotypes in either population. Frequency-dependent mating in the form of a rare male mating disadvantage for the In/In males tested against the St/St males in 731R was observed; the St/St males in this case showed a marginally significant rare male mating advantage. Thus, mating success as well as previously measured fecundity and fertility all indicate a selective advantage of the St chromosome over the In chromosome in both populations. This fitness relationship does not predict the equilibrium condition of 70–80% St/In, 20–30% In/In, and 0–10% St/St found in the DDT environment, whereas previously collected larval viability data and estimated adult survivorship do. In at least one population (731R), the adult mating success data do predict the dynamics of the polymorphism in the absence of DDT, whereas viability does not. These results, although limited to two populations under two environments (presence or absence of DDT), suggest that the relationship between adaptation to the environment under study and various components of fitness needs to be investigated fully before assessing which fitness components are most important in determining the effects of natural selection in specific populations.     

Antagonistic, stage-specific selection on defensive chemical sequestration in a toxic butterfly

Larvae of the pipevine swallowtail ( Battus philenor ) sequester toxic alkaloids called aristolochic acids from their Aristolochia host plants, rendering both larvae and adults chemically defended against most predators. Using a chemically controlled artificial diet, we observed substantial among-family variation in sequestration ability and larval developmental rate in a population occurring in central Texas. Early instar larvae from families that sequester greater amounts of aristolochic acid showed increased survivorship in a field experiment in which cohorts from each family were exposed to natural predators, whereas among-family variation in growth rate did not predict survivorship. Conversely, the aristolochic acid content of adult butterflies was negatively correlated with adult fat content, a fitness correlate. Sequestration ability positively affects the probability of larval survivorship, but at the cost of adult fat content. The costs and benefits of aristolochic acid sequestration vary during the course of the butterfly's development, and these antagonistic selection pressures may explain why variation in sequestration ability persists in wild populations.     

Comparative Population Dynamics of an Invading Species in its Native and Novel Ranges

Although the ecology of many exotic invaders has been intensively examined in the novel range, few studies have comparatively explored how population dynamics differ in native and novel parts of an invading plants’ range. The population dynamics of mile-a-minute weed, Polygonum perfoliatum L., was explored in both the native (Japan) and novel (northeastern USA) portions of its range and evaluated using periodic matrix models. Projected per capita population growth rate (λ) varied within and between native and novel range populations. Surprisingly, five of the six populations in the novel range were projected to fail to replace themselves (λ<1) while only two of the four native range populations were projected to decline, although these projections had wider confidence intervals than in the novel habitat. While changes in germination, survivorship, fecundity and seed banking would have equivalent effects on population growth in the invasive habitat, small increases in plant survivorship would greatly increase λ in native populations. The differences between native and novel population growth rates were driven by lower adult survival in the native range caused by annual flooding and higher fecundity. Simulation analyses indicated that a 50% reduction in plant survival would be required to control growing populations in the novel range. Further comparative studies of other invading species in both their native and novel ranges are needed to examine whether the high per capita population growth and strong regulatory effects of adult survival in the native habitat are generally predictive of invasive behavior in novel habitats. Sachiko Araki: (Deceased)     

Local adaptation of reproductive performance during thermal stress

Considerable evidence exists for local adaptation of critical thermal limits in ectotherms following adult temperature stress, but fewer studies have tested for local adaptation of sublethal heat stress effects across life‐history stages. In organisms with complex life cycles, such as holometabolous insects, heat stress during juvenile stages may severely impact gametogenesis, having downstream consequences on reproductive performance that may be mediated by local adaptation, although this is rarely studied. Here, we tested how exposure to either benign or heat stress temperature during juvenile and adult stages, either independently or combined, influences egg‐to‐adult viability, adult sperm motility and fertility in high‐ and low‐latitude populations of Drosophila subobscura. We found both population‐ and temperature‐specific effects on survival and sperm motility; juvenile heat stress decreased survival and subsequent sperm motility and each trait was lower in the northern population. We found an interaction between population and temperature on fertility following application of juvenile heat stress; although fertility was negatively impacted in both populations, the southern population was less affected. When the adult stage was also subject to heat stress, the southern population exhibited positive carry‐over effects whereas the northern population's fertility remained low. Thus, the northern population is more susceptible to sublethal reproductive consequences following exposure to juvenile heat stress. This may be common in other organisms with complex life cycles and current models predicting population responses to climate change, which do not take into account the impact of juvenile heat stress on reproductive performance, may be too conservative.     

Fitness components and ecological risk of transgenic release: a model using Japanese medaka (Oryzias latipes)

Any release of transgenic organisms into nature is a concern because ecological relationships between genetically engineered organisms and other organisms (including their wild-type conspecifics) are unknown. To address this concern, we developed a method to evaluate risk in which we input estimates of fitness parameters from a founder population into a recurrence model to predict changes in transgene frequency after a simulated transgenic release. With this method, we grouped various aspects of an organism's life cycle into six net fitness components: juvenile viability, adult viability, age at sexual maturity, female fecundity, male fertility, and mating advantage. We estimated these components for wild-type and transgenic individuals using the fish, Japanese medaka (Oryzias latipes). We generalized our model's predictions using various combinations of fitness component values in addition to our experimentally derived estimates. Our model predicted that, for a wide range of parameter values, transgenes could spread in populations despite high juvenile viability costs if transgenes also have sufficiently high positive effects on other fitness components. Sensitivity analyses indicated that transgene effects on age at sexual maturity should have the greatest impact on transgene frequency, followed by juvenile viability, mating advantage, female fecundity, and male fertility, with changes in adult viability, resulting in the least impact.     

More Status or More Children? Social Status,Fertility Reduction,and Long-Term Fitness

A model is presented that shows that reduced fertility in humans can be explained as part of an evolved strategy to maximize long-term fitness in the face of periodic calamities that result in demographic crashes. Three conditions must be met for this model to be plausible: (1) human population history has been characterized by local periods of growth punctuated by recurrent crashes caused by calamities such as climatically induced resource shortfalls; (2) a strategy is available to individuals that increases the probability of survival through a crash, but that, to implement, requires diverting resources away from producing more offspring; and (3) long-term fitness benefits to increased survivorship through a crisis must outweigh or equal the fitness benefits that would accrue to putting the same resources into higher fertility. We present a model that shows that increases in survivorship can outweigh the benefits of higher fertility even if crises are neither very frequent nor particularly severe.     

A Bayesian Geostatistical Moran Curve Model for Estimating Net Changes of Tsetse Populations in Zambia

For the first time a Bayesian geostatistical version of the Moran Curve, a logarithmic form of the Ricker stock recruitment curve, is proposed that is able to give an estimate of net change in population demographic rates considering components such as fertility and density dependent and density independent mortalities. The method is applied to spatio-temporally referenced count data of tsetse flies obtained from fly-rounds. The model is a linear regression with three components: population rate of change estimated from the Moran curve, an explicit spatio-temporal covariance, and the observation error optimised within a Bayesian framework. The model was applied to the three main climate seasons of Zambia (rainy – January to April, cold-dry – May to August, and hot-dry – September to December) taking into account land surface temperature and (seasonally changing) cattle distribution. The model shows a maximum positive net change during the hot-dry season and a minimum between the rainy and cold-dry seasons. Density independent losses are correlated positively with day-time land surface temperature and negatively with night-time land surface temperature and cattle distribution. The inclusion of density dependent mortality increases considerably the goodness of fit of the model. Cross validation with an independent dataset taken from the same area resulted in a very accurate estimate of tsetse catches. In general, the overall framework provides an important tool for vector control and eradication by identifying vector population concentrations and local vector demographic rates. It can also be applied to the case of sustainable harvesting of natural populations.     

Nonsurgical fertility control for managing free-roaming dog populations: A review of products and criteria for field applications

About 75% of dogs worldwide are free to roam and reproduce, thus creating locally overabundant populations. Problems caused by roaming dogs include diseases transmitted to livestock and humans, predation on livestock, attacks on humans, road traffic accidents, and nuisance behavior. Nonsurgical fertility control is increasingly advocated as more cost-effective than surgical sterilization to manage dog populations and their impact. The aims of this review were to 1) analyze trends in numbers of scientific publications on nonsurgical fertility control for dogs; 2) illustrate the spectrum of fertility inhibitors available for dogs; 3) examine how differences between confined and free-roaming dogs might affect the choice of fertility inhibitors to be used in dog population management; and 4) provide a framework of criteria to guide decisions regarding the use of nonsurgical fertility control for dog population management. The results showed that the 117 articles published between 1982 and 2011 focussed on long-term hormonal contraceptives, such as gonadotropin-releasing hormone agonists, immunocontraceptives, and male chemical sterilants. The number of articles published biennially increased from one to five papers produced in the early 1980s to 10 to 20 in the past decade. Differences between confined dogs and free-roaming dogs include reproduction and survival as well as social expectations regarding the duration of infertility, the costs of sterilization, and the responsibilities for meeting these costs. These differences are likely to dictate which fertility inhibitors will be used for confined or free-roaming dogs. The criteria regarding the use of fertility control for dog population management, presented as a decision tree, covered social acceptance, animal welfare, effectiveness, legal compliance, feasibility, and sustainability. The review concluded that the main challenges for the future are evaluating the feasibility, effectiveness, sustainability, and effects of mass nonsurgical sterilization campaigns on dog population size and impact as well as integrating nonsurgical fertility control with disease vaccination and public education programs.     

Compared biology of populations of Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) of Paraíba state, Brazil

The present work aims at comparing the life cycle and estimating, based on life tables, the patterns of fertility of populations of A. aegypti (L.). The life cycles were studied at the temperature of 26 +/- 2 degrees C, and 12h photophase. The development period, egg viability and larval and pupal survival were evaluated daily as well as adult longevity and fecundity. Tables of fertility life were built. The durations of egg, larva and pupa stages varied from 3,9 to 4,5 days, from 6,4 to 8,3 days and from 2,0 to 2,5 days, respectively. The life table parameters for A. aegypti from Brejo dos Santos, Boqueir?o, Itaporanga and Remígio, being, respectively, Ro = 104,03, 84,58, 113,37 and 91,18; rm = 0,92, 0,78, 0,89 and 0,88; and lambda = 2,50, 2,18, 2,43 and 2,41. The populations of Brejo dos Santos and Itaporanga had the biggest potential of growth in relation to the other populations. The results showed a differentiated pattern of growth and a biotical potential in the populations of A. aegypti originated from different municipal districts of the state of Paraíba.     

Assessment of possible ecological risks and hazards of transgenic fish with implications for other sexually reproducing organisms

Transgenic technology is developing rapidly; however, consumers and environmentalists remain wary of its safety for use in agriculture. Research is needed to ensure the safe use of transgenic technology and thus increase consumer confidence. This goal is best accomplished by using a thorough, unbiased examination of risks associated with agricultural biotechnology. In this paper, we review discussion on risk and extend our approach to predict risk. We also distinguish between the risk and hazard of transgenic organisms in natural environments. We define transgene risk as the probability a transgene will spread into natural conspecific populations and define hazard as the probability of species extinction, displacement, or ecosystem disruption given that the transgene has spread. Our methods primarily address risk relative to two types of hazards: extinction which has a high hazard, and invasion which has an unknown level of hazard, similar to that of an introduced exotic species. Our method of risk assessment is unique in that we concentrate on the six major fitness components of an organism's life cycle to determine if transgenic individuals differ in survival or reproductive capacity from wild type. Our approach then combines estimates of the net fitness parameters into a mathematical model to determine the fate of the transgene and the affected wild population. We also review aspects of fish ecology and behavior that contribute to risk and examine combinations of net fitness parameters which can lead to invasion and extinction hazards. We describe three new ways that a transgene could result in an extinction hazard: (1) when the transgene increases male mating success but reduces daily adult viability, (2) when the transgene increases adult viability but reduces male fertility, and (3) when the transgene increases both male mating success and adult viability but reduces male fertility. The last scenario is predicted to cause rapid extinction, thus it poses an extreme risk. Although we limit our discussion to aquacultural applications, our methods can easily be adapted to other sexually reproducing organisms with suitable adjustments of terminology.     

Possible risk posed by drift of the insect growth regulator pyriproxyfen to the rare dung beetle Circellium bacchus (F.) in a national park

Aerial drift of the juvenile hormone analogue (JHA), pyriproxyfen (Nemesis 100 ec®), used to control red scale on citrus on farms close to the Addo Elephant National Park in South Africa, was suspected of causing a decline in a population of the rare dung beetle species Circellium bacchus (F.) in the Park. The effect of pyriproxyfen on fertility and egg viability, as well as larval, pupal and callow adult development of C. bacchus was studied in a laboratory assay. Adult beetles, soil surface and the initial dung supply were exposed to pyriproxyfen applied as a spray at 10 times less than the concentration used commercially to simulate spray drift. Exposure of adult beetles to pyriproxyfen did not affect egg production or the viability of eggs, nor did the compound have adverse effects on immature development, indicating that pyriproxyfen is unlikely to be the cause of the observed population depression of C. bacchus.     

Dispersal in heterogeneous environments drives population dynamics and control of tsetse flies

Spatio-temporally heterogeneous environments may lead to unexpected population dynamics. Knowledge is needed on local properties favouring population resilience at large scale. For pathogen vectors, such as tsetse flies transmitting human and animal African trypanosomosis, this is crucial to target management strategies. We developed a mechanistic spatio-temporal model of the age-structured population dynamics of tsetse flies, parametrized with field and laboratory data. It accounts for density- and temperature-dependence. The studied environment is heterogeneous, fragmented and dispersal is suitability-driven. We confirmed that temperature and adult mortality have a strong impact on tsetse populations. When homogeneously increasing adult mortality, control was less effective and induced faster population recovery in the coldest and temperature-stable locations, creating refuges. To optimally select locations to control, we assessed the potential impact of treating them and their contribution to the whole population. This heterogeneous control induced a similar population decrease, with more dispersed individuals. Control efficacy was no longer related to temperature. Dispersal was responsible for refuges at the interface between controlled and uncontrolled zones, where resurgence after control was very high. The early identification of refuges, which could jeopardize control efforts, is crucial. We recommend baseline data collection to characterize the ecosystem before implementing any measures.     

A method for validating stochastic models of population viability: a case study of the mountain pygmy-possum (Burramys parvus)

1.  A method of validating stochastic models of population viability is proposed, based on assessing the mean and variance of the predicted population size.
2.  The method is illustrated with a model of the population dynamics of the mountain pygmy-possum ( Burramys parvus Broom 1895), based on annual census data collected from a single population in the Snowy Mountains of New South Wales, Australia between 1986 and 1997. The model incorporates density-dependence in survivorship and recruitment, and demographic and environmental stochasticity.
3.  The model appeared to make reasonable predictions for the three populations that were used for validation, provided the equilibrium population size was estimated accurately. This may require that differences in habitat quality between populations be taken into account.
4.  Following validation, the model was given new parameters using the additional data from the three populations, and the risk of population decline within the next 100 years was assessed. Although populations as small as 15 females are predicted to be relatively safe from extinction caused by stochastic processes, B. parvus appears vulnerable to loss of habitat and reductions in the population growth rate.
5.  The approach used in this paper is one of few attempts to validate a model of population viability using field data, and demonstrates that some aspects of stochastic population models can be tested.     

Survivorship characteristics of the mosquito Aedes caspius adults from southern France under laboratory conditions

The survivorship characteristics of two populations of Aedes caspius (Pallas) (Diptera: Culicidae) were compared in the laboratory. One population was sourced from Mourgues, where larvicides have been used continuously for approximately 40 years, and the other from Pont de Gau, where there has been no consistent mosquito control. The aims of the study were to ascertain the basic life history profiles of adults and to determine whether continuous larviciding affects inherent adult survivorship. Life tables were constructed to calculate the following life expectancy parameters: mean lifetime (tau(ad)); maximum lifetime (tau(max)), and daily survival rate (p(ad)). All three parameters were higher for females than for males (paired t-test, P < or = 0.001); male mean lifetime, maximum lifetime and daily survival rate were 4.95 +/- 0.94 days, 20.50 +/- 6.66 days and 0.79 +/- 0.05, respectively; female values were 14.74 +/- 3.68 days, 49.69 +/- 16.55 days and 0.93 +/- 0.02, respectively. No differences were found between the two populations, and no correlations were found between initial adult densities and their respective survival rates. The survivorship curves for Ae. caspius were type IV for males (mortality rates higher for young adults) and type III for females (mortality rates constant).     

EXPERIMENTAL EVOLUTION OF ACCELERATED DEVELOPMENT IN DROSOPHILA. 1. DEVELOPMENTAL SPEED AND LARVAL SURVIVAL

Developmental time is a trait of great relevance to fitness in all organisms. In holometabolous species that occupy ephemeral habitat, like Drosophila melanogaster, the impact of developmental time upon fitness is further exaggerated. We explored the trade-offs surrounding developmental time by selecting 10 independent populations from two distantly related selection treatments (CB_1-5 and CO_1-5) for faster development. After 125 generations, the resulting accelerated populations (ACB_1-5 and ACO_1-5) displayed net selection responses for development time of -33.4 hours (or 15%) for ACB and -38.6 hours (or 17%) for ACO. Since most of the change in egg-to-adult developmental time was accounted for by changes in larval duration, the “accelerated” larvae were estimated to develop 25-30% faster than their control/ancestor populations. The responses of ACB and ACO lines were remarkably parallel, despite being founded from populations evolved independently for more than 300 generations. On average, these “A” populations developed from egg to adult in less than eight days and produced fertile eggs less than 24 hours after emerging. Accelerated populations showed no change in larval feeding rate, but a reduction in pupation height, the latter being a trait relating to larval energetic expenditure in wandering prior to pupation. This experiment demonstrates the existence of a negative evolutionary correlation between preadult developmental time and viability, as accelerated populations experienced a severe cost in preadult survivorship. In the final assay generation, viability of accelerated treatments had declined by more than 10%, on average. A diallel cross demonstrated that the loss of viability in the ACO lines was not due to inbreeding depression. These results suggest the existence of a rapid development syndrome, in which the fitness benefits of fast development are balanced by fitness costs resulting from reduced preadult survivorship, marginal larval storage of metabolites, and reduced adult size.     

Extinction probabilities and times to extinction for populations of tsetse flies Glossina spp. (Diptera: Glossinidae) subjected to various control measures

A stochastic branching process was used to derive equations for the mean and variance of the probability of, and time to, extinction in tsetse populations. If the remnant population is a single inseminated female, the extinction probability increases linearly with adult mortality and is always certain if this mortality >3.5% per day even for zero pupal mortality. If the latter mortality is 4% per day, certain extinction is only avoided if adult mortality <1.5% per day. For remnant female populations >1, the extinction probability increases in a non-linear manner with adult mortality. Extinction is still certain for adult mortality >3.5% per day but, when the remnant population is >16, extinction is highly unlikely for adult mortality <2.5% per day if all females are inseminated. Extinction probability increases with increasing probability of sterile mating in much the same way as it does with increasing adult mortality. Extinction is assured if the probability of insemination can be reduced to 0.1. The required reduction decreases with increasing adult mortality. For adult mortality = 6-8% per day, the time to extinction increases only by one generation per order of magnitude increase in the starting population. Time to extinction is less sensitive to changes in the pupal than in the adult mortality. Reductions in the probability of insemination only become important when adult mortality is small; if the adult mortality is 8% per day, reducing the insemination probability from 1 to 0.1 only reduces the expected time to extinction by two generations. Conversely, increases in adult mortality produce important reductions in the required time even when the probability of insemination is 0.1. The practical, economic implication for the sterile insect technique is that the low-tech methods used to suppress tsetse populations should not be halted when the release of sterile males is initiated. The sterile insect technique should only be contemplated when it has been demonstrated that the low-tech methods have failed to effect eradication. The theory is shown to be in good accord with the observed results of tsetse control campaigns involving the use of odour-baited targets in Zimbabwe and the sterile insect technique on Unguja Island, Zanzibar.     

The coevolution of altruism and punishment: role of the selfish punisher

Punishment is an important mechanism promoting the evolution of altruism among non-relatives. We investigate the coevolution of altruism and punitive behavior, considering four possible strategies: the altruist punisher (AP, a cooperator who punishes defectors), the altruist non-punisher (AN, a pure cooperator), the selfish punisher (SP, a defector who punishes defectors), and the selfish non-punisher (SN, a pure defector). The SP uses a paradoxical strategy as it punishes other defectors. We analyse the effects of SP and AN on the coevolution of altruism and punishment. We study both the score-dependent viability model (whereby the game's score affects survivorship only) and the score-dependent fertility model (whereby the score affects fertility only). In the viability model of a completely mixed population, SP first drives out SN, and hence it helps cooperators (AP and AN) to evolve. In contrast, in the fertility model of a completely mixed population, neither SP nor AN helps the evolution of cooperation. In both the viability and fertility models of a lattice-structured population, SP promotes the spread of AP. In contrast, AN discourages the evolution of AP. These results can be understood that punishment is a form of spite behavior, paying a cost to reduce the fitness of the opponents, and that different models give different magnitude of advantage to spite behavior.     

Qualitative population divergence in proximate determination of a sexually selected trait in the collared flycatcher

We examined proximate determination of sexually selected forehead patch size in a Central‐European population of Ficedula albicollis, the collared flycatcher, using a 9‐year database, and compared our results with those obtained in other populations of the same and the sister species. Between‐individual variation of forehead patch size was large, its repeatability larger than, and heritability similar to the Swedish population. Unlike in the other populations, the trait proved unaffected by body condition, and only very slightly influenced by age. There was no relationship between forehead patch size and breeding lifespan, and a marginal negative association with survivorship in adult males. Our results suggest that additive genetic variance of the trait in this population is large, but genes act independently of body condition, and there is no viability indicator value of the trait. This is the first report of a qualitative intraspecific difference in proximate determination of a sexually selected trait.