Adult Population Size Research Articles

Associations between duck harvest, hunting wing ratios and measures of reproductive output in Northern Europe

Ducks are important game species, hunted in several countries throughout their annual cycle. We investigated whether the size of the annual duck harvest in Finland and Denmark reflected annual reproductive output in three common quarry duck species. Finland represents an important breeding area and Denmark important staging/wintering grounds for common teal (Anas crecca), Eurasian wigeon (Mareca penelope) and common goldeneye (Bucephala clangula). We assessed whether (i) annual duck harvest in these two countries correlated with variation in Finnish reproductive output or adult population size during 1990–2016 and (ii) variation in reproductive output of Finnish ducks was reflected in the juvenile ratios of birds harvested in Finland (2005–2007, 2014–2016) or Denmark (1990–2016). We hypothesised that variation in Finnish reproductive output would positively affect the size and juvenile ratio of the harvest, and that this effect would be stronger closer to the breeding grounds. Our data showed that the annual harvest of goldeneye in Finland was positively correlated with reproductive output, a desirable basis for applying sustainable management to this species. Teal and wigeon have much longer, more complex flyways, and their harvest did not mirror the annual production of young, although the wigeon harvest in Denmark increased with increasing juvenile ratio there. For these populations, we need to better define population units if we are to be able to assess harvest sustainability. We urgently need to monitor duck breeding success and harvest at larger spatial scales to support a comprehensive analysis of how well the harvest reflects reproductive output.

Habitat‐related differences in the adult longevity of two ecotypes of a specialized butterfly

AbstractThe life expectancy of adult butterflies is highly diverse. Substantial variation may be found among closely related species, and even on the intraspecific level, where it could be associated with sex, genetic differentiation, diet and weather conditions. We compared the demographic parameters of populations of the regionally endangered Boloria eunomia butterfly living in two different habitats. Across its boreal‐mountane distribution range in Europe, B. eunomia occurs in two ecotypes associated with wet meadows and raised bogs using distinct both larval and nectar plants. We carried out simultaneous studies of both ecotypes through mark–recapture surveys of two large populations in NE Poland, located close to each other. A total number of 1124 and 644 individuals were marked at the bog and meadow sites respectively, and 51 and 33% of them were recaptured at least once. The estimated adult population size of the bog population (about 3000) was twice as large as that of the meadow population, which however was characterized by more than three‐fold higher density. The emergence of imagoes was highly synchronized, and protandry was evident. The sex ratio was slightly male‐biased and the mean capture probability was significantly higher for males. More importantly, the estimated life span of males was considerably shorter than that of females at each site. Finally, both sexes of the ‘meadow’ ecotype lived significantly longer than those from the raised bog. The detected pattern can be related to distinct larval food plants and/or nectar resources, different pressures from predators, genetic variation and morphological differences affecting thermal properties. Further investigations would be useful to reveal if the shorter adult life span translates into reduced viability of bog populations and consequently whether they are potentially more threatened, at least in the southern margins of the distribution range in Central Europe.

Life stage‐specific, stochastic environmental effects overlay density dependence in an Atlantic salmon population

AbstractAtlantic salmon populations appear to fluctuate stochastically through time. It is suspected that both density‐dependent and density‐independent factors cause these fluctuations but the relative importance of each, and the life stages at which they operate, is not well known. In this study, a long‐term data set on Atlantic salmon migrants returning to the Foyle catchment, Ireland, was used to determine the role of density‐dependent and life stage‐specific environmental factors regulating population size. A Ricker density‐dependent model showed that spawning adult population size significantly predicted variation in the resultant filial generation; however, a large amount of variation (ca. 68%) remained unexplained. It was shown that environmental factors were significant in explaining some of the remaining variance and that these influences were linked to specific life stages. Three life stages—spawning and incubation, fry emergence and marine survival—were shown to have significant environmental effects that resulted in changes in the returning cohort strength. It is concluded that these life stage‐specific environmental effects are likely to contribute to the stochastic variation in population size resulting from the application of traditional stock–recruitment models. The identification and quantification of these effects should allow improved model accuracy.

Informing Public Health Prevention in NC Using Falls Surveillance Data

ObjectiveTo describe how a successful partnership between state public health and a university organization has used epidemiologic data, such as mortality, hospital discharge, and emergency department (ED) visit data, to inform falls prevention activities in North Carolina (NC).IntroductionFalls are a leading cause of fatal and nonfatal injury in NC. As the size of the older adult population is predicted to increase over the next few decades, it is likely that the incidence of falls-related morbidity and mortality will increase in tandem.1 In order to address this public health emergency, the Injury and Violence Prevention Branch (IVPB) of the NC Division of Public Health has partnered with the Carolina Center for Health Informatics (CCHI) in the Department of Emergency Medicine at the University of North Carolina at Chapel Hill to perform falls surveillance activities. This abstract describes some of the specific research and surveillance activities currently ongoing in NC.MethodsIVPB developed the Special Emphasis Report (SER) on Fall Injuries among Older Adults, 2005-2014 to describe the demographic characteristics and trends of falls-related mortality and hospitalization among adults 65 and older, associated costs of falls-related injury, and current falls prevention activities in NC. The NC SER was based on the Centers for Disease Control and Prevention’s Injury SER template, a tool designed to facilitate the dissemination of injury data for public health action.While the SER focused primarily on falls among adults >65 years of age, CCHI was interested in using ED visit data to identify the age at which falls morbidity begins to increase as a means of informing prevention activities to be implemented before the advent of an injurious fall. Therefore, CCHI performed a descriptive epidemiologic study using ED visit data collected by NC DETECT. CCHI identified all NC ED visits from January 1, 2010 – December 31, 2014 that met the National Center for Injury Prevention and Control definition of a fall of unintentional intent.2 During 2010-2014, NC DETECT captured ED visit data from all 125 24/7, acute care, hospital-affiliated, civilian EDs and over 99% of all ED visits in the state.3ResultsAnalysis for the SER found that falls-related death rates increased by 43.1% from 2005 (47.0 per 100,000) to 2014 (67.3 per 100,000), with the greatest increase among males (61.3%) and adults 85 and older (74.4%). Conversely, rates of non-fatal hospitalization remained relatively stable and were 1.6 times higher among females than males in 2014 (84.0 and 56.8 per 100,000 respectively). Projected lifetime costs associated with falls among NC older adults was approximately $1.4 billion in 2014.NC DETECT captured 986,024 ED visits during the period 2010-2014 among adults >20 years of age (27.4 ED visits/1,000 person-years; 95% CI: 27.4-27.5). Throughout the adult lifespan, fall incidence rates in women (33.0 ED visits/1,000 person-years; 95% CI: 32.9-33.1) exceeded those in men (21.3 ED visits/1,000 person-years; 95% CI: 21.3-21.4). Starting at age 45, fall rates in women continued to exceed fall rates in men, climbing each year, while rates in men remained stable until after age 65. These results suggest that the risk of having an injurious fall may increase before age 65, particularly among women.Due to the public health implications of the results obtained by IVPB and CCHI, both organizations are working closely to ensure that relevant information reaches a wide net of potential partners in the effort to reduce falls morbidity and mortality. To date, IVPB and CCHI have collaborated on generating fact sheets and short reports available to the public, syndromic surveillance custom event reports available to authorized users, and presenting information to local, state, and national partners.ConclusionsFalls morbidity and mortality are major concerns for the state of NC and the country as a whole. Falls surveillance benefits from the collaboration of governmental and university organizations with community partners. For example, when CCHI identified an increase in falls incidence in middle age, and, therefore, the potential need to begin falls risk assessment activities at ages < 65, particularly among women, NC DPH had the resources to communicate these results to relevant local and state programs and organizations.

Colony defensive behavior by the swarm-founding wasp Parachartergus pseudoapicalis: increase on investment predicts the intensity of nest defense

The parental investment (PI) theory predicts that animals that have the ability to care for their offspring should defend them with an optimal intensity to minimize the risks of predation. This study evaluates the stages of development that are more valued and, therefore, are more protected by the colonies of the founding wasp Parachartergus pseudoapicalis. We determined the effects on the colony defense intensity of colony size, adult population, and immature population size for different stages. As predicted by PI theory, we found that defense intensity was related to colony investment in offspring. In addition, we found no association between the number of adults in the colony and the defense intensity, whereas a greater number of immatures in the pupal stage in the colony led to greater defense intensity. Our study highlights the importance of parental care in social insects and the changes in defense behavior present in colonies with different compositions of individuals at different stages.

Collaborating with recreational fishers to inform fisheries management: Estimating population abundance for an iconic freshwater crayfish

SummaryCan the abundance of fish populations be effectively determined by the collection of scientific research with support from recreational fishers? Collecting and analysing fishing data from recreational fishers to aid management are not new; however, engaging fishers in a scientific survey design to produce specific population estimates is rarely undertaken. We engaged recreational fishers to assist with field sampling to provide an estimate Murray Crayfish (Euastacus armatus von Martens, 1866) abundance at three sites on the Edward River which were recently impacted by an extreme blackwater disturbance. Employing mark‐resight models, fishers undertook crayfish surveys and produced research data which estimated adult population sizes of Murray Crayfish in the studied reaches ranging between 94.27 ± 24.72 individuals (Below Stevens) and 450.01 ± 175.30 individuals (Twin Rivers). Both the effective undertaking of the mark‐resight designs in collaboration with fishers and acquiring population abundance estimates for Murray Crayfish in a river reach are concepts which have not previously been published and are important attributes for the management of aquatic species.

An integrative mating system assessment of a nonmodel, economically important Pacific rockfish (Sebastes melanops) reveals nonterritorial polygamy and conservation implications for a large species flock.

Characterizing the mating systems of long‐lived, economically important Pacific rockfishes comprising the viviparous Sebastes species flock is crucial for their conservation. However, direct assignment of mating success to sires is precluded by open, offshore populations and high female fecundity. We addressed this challenge by integrating paternity‐assigned mating success of females with the adult sex ratio (ASR) of the population, male evolutionary responses to receptive females, and reproductive life history traits—in the framework of sexual selection theory—to assess the mating system of Sebastes melanops. Microsatellite parentage analysis of 17 pregnant females, 1,256 of their progeny, and 106 adults from the population yielded one to four sires per brood, a mean of two sires, and a female mate frequency distribution with a truncated normal (random) pattern. The 11 multiple paternity broods all contained higher median allele richness than the six single paternity broods (Wilcoxon test: W = 0, p < .001), despite similar levels of average heterozygosity. By sampling sperm and alleles from different males, polyandrous females gain opportunities to enhance their sperm supply and to lower the cost of mating with genetically incompatible males through reproductive compensation. A mean of two mates per mated female with a variance of one, an ASR = 1.2 females per male, and the expected population mean of 2.4 mates for mated males (and the estimated 35 unavailable sires), fits polygamous male mate frequency distributions that distinguish polygynandry and polyandrogyny mating systems, that is, variations of polygamy, but not polyandry. Inference for polygamy is consistent with weak premating sexual selection on males, expected in mid‐water, schooling S. melanops, owing to polyandrous mating, moderately aggregated receptive females, an even ASR, and no territories and nests used for reproduction. Each of these characteristics facilitates more mating males and erodes conspicuous sexual dimorphism. Evaluation of male evolutionary responses of demersal congeners that express reproductively territorial behavior revealed they have more potential mechanisms for producing premating sexual selection, greater variation in reproductive success, and a reduced breeding effective population size of adults and annual effective size of a cohort, compared to S. melanops modeled with two mates per adult. Such divergence in behavior and mating system by territorial species may differentially lower their per capita birth rates, subsequent population growth, and slow their recovery from exploitation.

Evolutionary rescue in a host-pathogen system results in coexistence not clearance.

The evolutionary rescue of host populations may prevent extinction from novel pathogens. However, the conditions that facilitate rapid evolution of hosts, in particular the population variation in host susceptibility, and the effects of host evolution in response to pathogens on population outcomes remain largely unknown. We constructed an individual‐based model to determine the relationships between genetic variation in host susceptibility and population persistence in an amphibian‐fungal pathogen (Batrachochytrium dendrobatidis) system. We found that host populations can rapidly evolve reduced susceptibility to a novel pathogen and that this rapid evolution led to a 71‐fold increase in the likelihood of host–pathogen coexistence. However, the increased rates of coexistence came at a cost to host populations; fewer populations cleared infection, population sizes were depressed, and neutral genetic diversity was lost. Larger adult host population sizes and greater adaptive genetic variation prior to the onset of pathogen introduction led to substantially reduced rates of extinction, suggesting that populations with these characteristics should be prioritized for conservation when species are threatened by novel infectious diseases.

Genetic evidence of fragmented populations and inbreeding in the Colombian endemic Dahl’s toad-headed turtle (Mesoclemmys dahli)

Population fragmentation is one of the most concerning consequences of habitat fragmentation, as small and isolated populations suffer increased genetic drift and inbreeding. However, the extent to which habitat fragmentation leads to population fragmentation depends not only on the landscape structure, but also on the response of organisms to it. This behavioral component makes it difficult to detect population fragmentation even if the habitat is fragmented, unless appropriate tools are used. In this study, we used a molecular approach to evaluate if Dahl’s toad-headed turtle (Mesoclemmys dahli) population was fragmented, given that it occurs in a very restricted area within the most degraded biome of Colombia, the tropical dry forest. We developed a panel of 15 microsatellite loci in order to perform the first genetic assessment of M. dahli across its complete geographic range. We found that M. dahli has significant genetic structure with at least four subpopulations, with surprisingly moderate to high levels of genetic diversity. Despite high levels of genetic diversity, subpopulations are very small (effective population sizes < 50) and isolated, with little to no contemporary gene flow among them. As a consequence, mating among related individuals has been occurring, and all four populations are showing high degrees of inbreeding. To counteract this threat, we recommend an urgent genetic rescue strategy accompanied by habitat restoration, and advocate for a new conservation status assessment, not based on geographic range, but on adult population size and level of fragmentation.

Comparison of the activity and productivity of Carniolan (Apis mellifera carnica Pollmann) and Yemeni (Apis mellifera jemenitica Ruttner) subspecies under environmental conditions of the Al-Ahsa oasis of eastern Saudi Arabia.

This study was conducted at the apiary of the Agricultural and Veterinary Training and Research Station of King Faisal University in the Al-Ahsa oasis of eastern Saudi Arabia. We performed a comparison between Carniolan (Apis mellifera carnica Pollmann) and Yemeni (Apis mellifera jemenitica Ruttner) honeybee races to determine the monthly fluctuations in foraging activity, pollen collection, colony growth and honey yield production under the environmental conditions of the Al-Ahsa oasis of eastern Saudi Arabia. We found three peaks in the flight activity of the two races, and the largest peaks occurred during September and October. Compared to Carniolan bee colonies, the performance of Yemeni bee colonies was superior in terms of stored pollen, worker and drone brood rearing, and the adult population size. The Carniolan bee colonies produced 27.77% and 27.50% more honey than the Yemeni bee colonies during the flow seasons of alfalfa and sidir, respectively, with an average increase of 27.64%. It could be concluded that the race of bees is an important factor affecting the activity and productivity of honeybee colonies. The Yemeni bee race produced more pollen, a larger brood and more bees, which exhibited a longer survival. The imported Carniolan bees can be reared in eastern Saudi Arabia, but the Yemeni bee race is still better.

Population monitoring of an urban gliding mammal in eastern Australia

Long-term monitoring is an important element of species conservation. This study describes changes in the size of a squirrel glider (Petaurus norfolcensis) population over a 10-year period. The population occupied a 45-ha forest remnant within the urban area of Brisbane. Gliders were tagged from 25 nights of trapping during 2006–08 and from 16 nights of trapping in 2015. Population modelling was used to estimate adult population size. This suggested the adult population comprised 30–40 individuals at the beginning and end of the 10-year period. It reached a peak of 70 individuals in mid-2007. These data suggest that the study area contains a small population that is prone to interannual variation but there was no evidence of it being in decline. Survival estimates during 2006–08 were equivalent to those estimated for a larger population in Victoria. Population monitoring should be continued to determine how resilient this population is to population decline and to investigate factors that may cause decline. This study provides an example of an approach that could be used to monitor threatened populations of the squirrel glider.

Can collective memories shape fish distributions? A test, linking space‐time occurrence models and population demographics

Social learning can be fundamental to cohesive group living, and schooling fishes have proven ideal test subjects for recent work in this field. For many species, both demographic factors, and inter‐ (and intra‐) generational information exchange are considered vital ingredients in how movement decisions are reached. Yet key information is often missing on the spatial outcomes of such decisions, and questions concerning how migratory traditions are influenced by collective memory, density‐dependent and density‐independent processes remain open. To explore these issues, we focused on Atlantic herring Clupea harengus, a long‐lived, dense‐schooling species of high commercial importance, noted for its unpredictable shifts in winter distribution, and developed a series of Bayesian space‐time occurrence models to investigate wintering dynamics over 23 yr, using point‐referenced fishery and survey records from Icelandic waters. We included covariates reflecting local‐scale environmental factors, temporally‐lagged prey biomass and recent fishing activity, and through an index capturing distributional persistence over time, derived two proxies for spatial memory of past wintering sites. The previous winter's occurrence pattern was a strong predictor of the present pattern, its influence increasing with adult population size. Although the mechanistic underpinnings of this result remain uncertain, we suggest that a ‘wisdom of the crowd’ dynamic may be at play, by which navigational accuracy towards traditional wintering sites improves in larger and/or denser, better synchronized schools. Wintering herring also preferred warmer, fresher, moderately stratified waters of lower velocity, close to hotspots of summer zooplankton biomass, our results indicative of heightened environmental sensitivity in younger cohorts. Incorporating spatiotemporal correlation structure and time‐varying regression coefficients improved model performance, and validation tests on independent observations one‐year ahead illustrate the potential of uniting demographic information and non‐stationary models to quantify both the strength of collective memory in animal groups and its relevance for the spatial management of populations.

Unexpected high genetic diversity in small populations suggests maintenance by associative overdominance

The effective population size (Ne ) is a central factor in determining maintenance of genetic variation. The neutral theory predicts that loss of variation depends on Ne , with less genetic drift in larger populations. We monitored genetic drift in 42 Drosophila melanogaster populations of different adult census population sizes (10, 50 or 500) using pooled RAD sequencing. In small populations, variation was lost at a substantially lower rate than expected. This observation was consistent across two ecological relevant thermal regimes, one stable and one with a stressful increase in temperature across generations. Estimated ratios between Ne and adult census size were consistently higher in small than in larger populations. The finding provides evidence for a slower than expected loss of genetic diversity and consequently a higher than expected long-term evolutionary potential in small fragmented populations. More genetic diversity was retained in areas of low recombination, suggesting that associative overdominance, driven by disfavoured homozygosity of recessive deleterious alleles, is responsible for the maintenance of genetic diversity in smaller populations. Consistent with this hypothesis, the X-chromosome, which is largely free of recessive deleterious alleles due to hemizygosity in males, fits neutral expectations even in small populations. Our experiments provide experimental answers to a range of unexpected patterns in natural populations, ranging from variable diversity on X-chromosomes and autosomes to surprisingly high levels of nucleotide diversity in small populations.

Evaluating management strategies in the conservation of the critically endangered Blue-throated Macaw (Ara glaucogularis)

We model the dynamics of the remaining wild population of the Blue-throated Macaw (Ara glaucogularis), a critically endangered and Bolivian endemic species exposed to different management strategies. The model becomes a tool to quantify how effective management actions may be. We construct a birth-pulse, post breeding census, deterministic, stage structured projection matrix model to describe the population dynamics. The model shows that population growth is sensitive to changes in the probability of survival in the adult stage, followed by changes in fertility. We describe the long-term behavior of the population as result of the combination of the maternity function and the nestlings’ survival probability. Under the scenarios of increasing population, the number of years that are necessary to double the current wild population varied between 33 and 215 years without reintroduction, and between 7 and 46 years if 50 adult macaws are reintroduced ten years later since the simulation starts. Stakeholders of the Blue-throated Macaw Conservation Project may profit from a simple graphical tool based on this model for management decision making. By knowing the adult population size and the number of hatched eggs at the beginning of each breeding season, the field team could assess the necessary effort on nestlings’ management to increase the chances of a positive population growth. Evaluating beforehand the impact of management actions on Blue-throated Macaws could contribute to the improvement and effectiveness of conservation actions on the critically endangered Blue-throated Macaw population.

Fine-scale differences in genetic and census population size ratios between two stream fishes

Comparing the ratio of effective number of breeders (N b ) to adult population size (N) among closely related coexisting species can provide insights into the role of life history on N b /N ratios and inform conservation programs towards limiting the loss of evolutionary potential in natural populations. We estimated N b and N in two coexisting salmonid fishes (Brook trout and Atlantic salmon) for 3–4 consecutive years in two small, adjacent streams in Newfoundland, Canada, using mark-recapture (N), linkage disequilibrium (N b(LD)), and sibship frequency approaches (N b(Sib) ). We found that N b /N ratios were about 20-fold greater in Atlantic salmon than in brook trout (mean 0.20, range 0.06–0.56 vs. mean 0.02, range 0.01–0.05, respectively). This difference was consistent across N b estimators. In addition, we found that removing migrants reduced N b : the strength of the effect was weak for N b(LD) and much stronger for N b(Sib). Our results highlight the importance of subtle ecological differences and gene flow in shaping N b /N. They also provide some evidence that the linkage between demographic and evolutionary processes varies between closely related taxa and suggest that a more complete understanding of the N b /N range across various species is an important component of conservation genetics and management.

Effective size of density-dependent two-sex populations: the effect of mating systems.

Density dependence in vital rates is a key feature affecting temporal fluctuations of natural populations. This has important implications for the rate of random genetic drift. Mating systems also greatly affect effective population sizes, but knowledge of how mating system and density regulation interact to affect random genetic drift is poor. Using theoretical models and simulations, we compare Ne in short-lived, density-dependent animal populations with different mating systems. We study the impact of a fluctuating, density-dependent sex ratio and consider both a stable and a fluctuating environment. We find a negative relationship between annual Ne /N and adult population size N due to density dependence, suggesting that loss of genetic variation is reduced at small densities. The magnitude of this decrease was affected by mating system and life history. A male-biased, density-dependent sex ratio reduces the rate of genetic drift compared to an equal, density-independent sex ratio, but a stochastic change towards male bias reduces the Ne /N ratio. Environmental stochasticity amplifies temporal fluctuations in population size and is thus vital to consider in estimation of effective population sizes over longer time periods. Our results on the reduced loss of genetic variation at small densities, particularly in polygamous populations, indicate that density regulation may facilitate adaptive evolution at small population sizes.

Supply-side control over the survivorship of Chthamalus spp. recruits in northern Baja California

ABSTRACTThe constant supply of larvae to coastal habitats is important for the persistence of populations and can vary depending on oceanic conditions that may affect physical transport processes. We evaluated the survivorship of Chthamalus recruits in Playa San Miguel, Baja California, for over a year to evaluate if the supply of new recruits was of greater importance than the post-recruitment factors of competition and predation in determining adult population size. We hypothesized that the number of Chthamalus recruits would predict the number of adults present and that predation and competition would not play a significant role in determining adult densities. Recruit density was a robust predictor of adult density despite the presence of weak density-dependent mortality. Neither predation nor competition significantly affected the survivorship of recruits and did not decouple the relationship between recruit and adult densities, suggesting that these post-recruitment controls did not play an important role in determining the population size of Chthamalus barnacles at this site. The data support the hypothesis that supply-side control is the primary factor structuring the population of Chthamalus in the intertidal community at Playa San Miguel.

Tri-spine horseshoe crab, Tachypleus tridentatus (L.) in Sabah, Malaysia: the adult body sizes and population estimate

The dwindling number of the tri-spine horseshoe crab, Tachypleus tridentatus has been reported globally and its status in Malaysia is not much known. Study on dimorphism in adult body sizes and population size estimation were conducted using capture–mark–recapture method of adult T. tridentatus in Tawau, Sabah. Camry the estimated population sizes of T. tridentatus ranged from 182 to 1095 with 95% confident limits of 56–42,942 individuals (Schnabel formula). The multivariate discriminant Hotelling’s T2 test verifies the sexual size dimorphism among the adult T. tridentatus with 97.7% separation among sexes (Hotelling’s T2 = 778.49, F = 152.85, p < 0.001) with females being larger and heavier than the male individuals. The number estimated from the study is the first reported for T. tridentatus in Malaysia, particularly in Sabah. Even though this number may slightly overestimate the actual population size in the area owing to the low number of individuals recaptured, for now it could serve as baseline data for horseshoe crab management purpose.

Mimetic asociations in natural populations of tropical papilionid butterflies. I. Life history and structure of a tropical dry forest breeding population of Battus polydamus polydamus

A small breeding population of the butterfly Battus polydamus polydamus Linnaeus was studied at a tropical dry forest site in northwestern (Guanacaste Province), Costa Rica, from March through June, 1970. Life history, adult population size, adult turnover, adult dispersal, breeding behavior, territorial behavior and biotic mortality in larval populations were studied. It was condud­ ed that the apparent patchy distribution of the larval foodplant ( Aristolochia vines ) results in a very patchy distribution of breeding populations of this but terfly; low vagility, high adult survivorship and localized breeding interactions at the larval foodplant account for the apparent high population cohesiveness in this species, despite high levels of parasitism during the larval stage. Males eclose before females and establish territories at the breeding site and adult numbers remain consistent over long periods of time. The latter is believed to be a result of high adult survivorship (from predation by birds), with low mor­ tality associated with old age being counterbalanced with low recruitment of new adults to the population. The relation of such a population structure to mimicry theory is also discussed.

The carry‐over effects of pollen shortage decrease the survival of honeybee colonies in farmlands

Summary Many studies have reported honeybee colony losses in human‐dominated landscapes. While bee floral food resources have been drastically reduced over past decades in human‐dominated landscapes, no field study has yet been undertaken to determine whether there is a carry‐over effect between seasonal disruption in floral resource availability and high colony losses. We investigated if a decline in the harvest of pollen by honeybees in spring affected managed honeybee colony dynamics (brood size, adult population and honey reserves) and health (Varroa mite loads and colony survival) throughout the beekeeping season. A decline in pollen harvest was associated with a direct reduction in brood production, leading to a negative effect on the adult population size later in the season, and lower honey reserves before the onset of winter. Furthermore, the decline in pollen harvest negatively impacted the health of the colony, resulting in higher Varroa mite loads and higher seasonal and winter colony losses. Early‐warning signs of these carry‐over effects were identified, showing that preferential investment in honey reserves instead of brood production early in the season increased the decline in pollen harvest and its associated carry‐over effects. Synthesis and applications. The results suggest that the decline in pollen harvest may have been overlooked as a cause of pollen shortage and associated bee colony losses. Strategies to avoid such losses in intensive farmland systems include (i) limiting or avoiding honey harvests in spring, (ii) monitoring colonies for early‐warning signals of colony failure and (iii) increasing the amount of floral resources available through wise land‐use management.