Metapopulation dynamics in a changing climate: Increasing spatial synchrony in weather conditions drives metapopulation synchrony of a butterfly inhabiting a fragmented landscape

Habitat fragmentation and climate change are both prominent manifestations of global change, but there is little knowledge on the specific mechanisms of how climate change may modify the effects of habitat fragmentation, for example, by altering dynamics of spatially structured populations. The long‐term viability of metapopulations is dependent on independent dynamics of local populations, because it mitigates fluctuations in the size of the metapopulation as a whole. Metapopulation viability will be compromised if climate change increases spatial synchrony in weather conditions associated with population growth rates. We studied a recently reported increase in metapopulation synchrony of the Glanville fritillary butterfly (Melitaea cinxia) in the Finnish archipelago, to see if it could be explained by an increase in synchrony of weather conditions. For this, we used 23 years of butterfly survey data together with monthly weather records for the same period. We first examined the associations between population growth rates within different regions of the metapopulation and weather conditions during different life‐history stages of the butterfly. We then examined the association between the trends in the synchrony of the weather conditions and the synchrony of the butterfly metapopulation dynamics. We found that precipitation from spring to late summer are associated with the M. cinxia per capita growth rate, with early summer conditions being most important. We further found that the increase in metapopulation synchrony is paralleled by an increase in the synchrony of weather conditions. Alternative explanations for spatial synchrony, such as increased dispersal or trophic interactions with a specialist parasitoid, did not show paralleled trends and are not supported. The climate driven increase in M. cinxia metapopulation synchrony suggests that climate change can increase extinction risk of spatially structured populations living in fragmented landscapes by altering their dynamics.     

European butterfly populations vary in sensitivity to weather across their geographical ranges

Aim

The aim was to assess the sensitivity of butterfly population dynamics to variation in weather conditions across their geographical ranges, relative to sensitivity to density dependence, and determine whether sensitivity is greater towards latitudinal range margins.

Location

Europe.

Time period

1980–2014.

Major taxa studied

Butterflies.

Methods

We use long‐term (35 years) butterfly monitoring data from > 900 sites, ranging from Finland to Spain, grouping sites into 2° latitudinal bands. For 12 univoltine butterfly species with sufficient data from at least four bands, we construct population growth rate models that include density dependence, temperature and precipitation during distinct life‐cycle periods, defined to accommodate regional variation in phenology. We use partial R² values as indicators of butterfly population dynamics' sensitivity to weather and density dependence, and assess how these vary with latitudinal position within a species' distribution.

Results

Population growth rates appear uniformly sensitive to density dependence across species' geographical distributions, and sensitivity to density dependence is typically greater than sensitivity to weather. Sensitivity to weather is greatest towards range edges, with symmetry in northern and southern parts of the range. This pattern is not driven by variation in the magnitude of weather variability across the range, topographic heterogeneity, latitudinal range extent or phylogeny. Significant weather variables in population growth rate models appear evenly distributed across the life cycle and across temperature and precipitation, with substantial intraspecific variation across the geographical ranges in the associations between population dynamics and specific weather variables.

Main conclusions

Range‐edge populations appear more sensitive to changes in weather than those nearer the centre of species' distributions, but density dependence does not exhibit this pattern. Precipitation is as important as temperature in driving butterfly population dynamics. Intraspecific variation in the form and strength of sensitivity to weather suggests that there may be important geographical variation in populations' responses to climate change.     

Turnover and trends in butterfly communities on two British tidal islands: stochastic influences and deterministic factors

Aim Community trends were investigated for two small islands and two local mainland butterfly communities within the UK over a period of 20–30 years. Location Hilbre Island off the Wirral Peninsula at 53.33° N, 3.10° W; Lindisfarne, an island off the Northumberland coast at 56.41° N, 1.48° W; Leighton Moss at 54.08° N, 2.26° W; Wyre Forest at 52.23° N, 2.14° W, UK. Methods Butterfly species data were collected on Hilbre and two mainland sites (Leighton Moss and Wyre Forest) from 1983 to 2006, and on Lindisfarne from 1977 to 2006, as part of the National Habitat Survey, the UK Butterfly Monitoring Scheme and ‘Butterflies for the New Millennium Atlas’ recording. Matrices of associations (Sokal and Michener’s matching coefficient S_SM; resemblance coefficient) were computed between years and subject to non‐metric multidimensional scaling (NMDS) and Mantel tests. The pattern of extinctions and colonizations at sites were examined, their heterogeneity tested by applying a Friedman test to fractional incidences for the same years. Regression analysis (multiple regression and logit regression) was used to relate butterfly numbers and incidences to climate variables, time and previous records. Results Significant community trends based on population counts and species’ incidences were found for all four sites. There was a significant climatic signal for Hilbre; although this was not apparent for the remaining sites, significant associations occurred between records for a number of species and climatic variables at all sites. Substantial turnover of species on the islands was inversely related to numbers of records for species but not to their conspicuousness to recorders. Main conclusions We argue that time trends are widespread in butterfly communities, even for relatively short periods; they are largely generated by stochastic influences rather than by more substantive factors such as climate change. Potential biases in surveying and recording history are shown to be unlikely. A clear climate signal was found only for the small Hilbre Island, for which there was also evidence for the significant influence of colonization capability of individual source species. We conclude that for many species, small islands will be sinks or pseudosinks and their ‘populations’ vulnerable to small changes in source–sink dynamics.     

Assessing species’ habitat associations from occurrence records,standardised monitoring data and expert opinion: A test with British butterflies

Accurate knowledge of species’ habitat associations is important for conservation planning and policy. Assessing habitat associations is a vital precursor to selecting appropriate indicator species for prioritising sites for conservation or assessing trends in habitat quality. However, much existing knowledge is based on qualitative expert opinion or local scale studies, and may not remain accurate across different spatial scales or geographic locations. Data from biological recording schemes have the potential to provide objective measures of habitat association, with the ability to account for spatial variation. We used data on 50 British butterfly species as a test case to investigate the correspondence of data-derived measures of habitat association with expert opinion, from two different butterfly recording schemes. One scheme collected large quantities of occurrence data (c. 3 million records) and the other, lower quantities of standardised monitoring data (c. 1400 sites). We used general linear mixed effects models to derive scores of association with broad-leaf woodland for both datasets and compared them with scores canvassed from experts.Scores derived from occurrence and abundance data both showed strongly positive correlations with expert opinion. However, only for occurrence data did these fell within the range of correlations between experts. Data-derived scores showed regional spatial variation in the strength of butterfly associations with broad-leaf woodland, with a significant latitudinal trend in 26% of species. Sub-sampling of the data suggested a mean sample size of 5000 occurrence records per species to gain an accurate estimation of habitat association, although habitat specialists are likely to be readily detected using several hundred records. Occurrence data from recording schemes can thus provide easily obtained, objective, quantitative measures of habitat association.     

Drivers of hybridization in a 66-generation record of Colias butterflies

Hybridization significantly affects the ecology and evolution of numerous plant and animal lineages. Most studies have focused on endogenous drivers of hybridization and neglected variation in exogenous factors, such as seasonal weather patterns. In this study, we take advantage of a unique dataset consisting of records of hybridization between the butterflies Colias eurytheme and C. eriphyle (Pieridae) for 66 generations (22 years) to investigate the importance of seasonal weather on the production and survival of hybrid offspring. Important seasonal weather variables for each parental species and hybrid offspring were determined using model averaging, and these weather variables, along with butterfly abundances, were analyzed using path analysis. The most important drivers of hybridization were the abundance of C. eriphyle, summer minimum temperature, and spring maximum temperature. In contrast, the abundance of C. eurytheme and weather variables prior to the current flight season were relatively unimportant for variation in hybrid abundance. Parental abundances were mostly driven by weather variables prior to the flight season possibly because these variables affect host plant quality. Our results suggest that exogenous, climatic factors can influence hybridization in natural systems, and that these factors can act both directly on hybrid abundance and indirectly through the population dynamics of parental species.     

Using anglers' records in Poland as a tool for assessing changes in fish body weight caused by fluctuations of inland water quality

Anglers' records of fish weight (ARFW) were analysed in Poland for the periods 1965–1989 (successive increases in inland water pollution), and 1990–2010 (considerable improvements in water quality). For the initial ARFW analysis, the entire study was divided into nine intervals of 5 years each; the period that followed was divided into three catchments: the Vistula, Oder and Pomeranian rivers, whereby 10 species were chosen to represent obligatory riverine and facultative species. With a few exceptions, the investigated species showed unexpected and varying reactions to the changes in water quality. The ARFW of obligatory riverine barbel Barbus barbus (L.) decreased during the first periods (1965–1989), then increased significantly from 1990 to 2010. For obligatory riverine ide Leuciscus idus (L.), tendencies were less clear but as significant. However, other obligatory riverine species have not shown a relationship between ARFW and water quality. Discrepancies were also recorded in the facultative riverine pike (Esox lucius L.) and brown trout (Salmo trutta L.). Considering the number of medals recorded, there were some interesting tendencies related to the decline or improvement in the water quality, although not in all investigated species. The species displaying a decrease in medals awarded from 1966 to 1989 and increasing after 1990, was chub Leuciscus cephalus (L.), but only until 2005. Species which showed successive increases in awards from 1989 to 2010 were: pike, perch (Perca fluviatilis L.), ide, and wels (Silurus glanis L.). However, for species in the period when the water quality actually deteriorated (1966–1990), the number of medals awarded increased: barbel, brown trout (S. trutta L.), and grayling Thymallus thymallus (L.).     

Influence of weather factors on population dynamics of two lagomorph species based on hunting bag records

Weather conditions can have a significant influence on short-term fluctuations of animal populations. In our study, which is based on time series of hunting bag records of up to 28?years from 26 counties of The Netherlands and Germany, we investigated the impact of different weather variables on annual counts of European rabbits (Oryctolagus cuniculus) and European hares (Lepus europaeus). Overall, the long-term dynamics of both species could be described by higher-order polynomials. On a smaller time scale, the number of European hares shot was lower in years with higher amounts of precipitation during late summer/autumn, and the number of European rabbits shot was lower in years with high precipitation in spring of the respective year. We suggest that rainy weather conditions might have lowered the survival of young rabbits in spring and might have generally facilitated the outbreak or spread of diseases in rabbits as well as in hares, specifically in autumn. In addition, the results showed a time-delayed, interactive effect between precipitation in spring and winter weather on European rabbit dynamics: rabbit numbers were limited by low temperatures of the prior winter season, but only when precipitation was high during spring of the previous year. The latter result might be explained by the lowering effects of rainy spring weather on the body condition of the animals, leading to higher sensitivity to harsh winter conditions. In conclusion, our study provides evidence for the impact of weather conditions on the population dynamics of both study species and particularly highlights complex interactions between the prevailing weather conditions during different seasons in the European rabbit.     

Alien ants (Hymenoptera: Formicidae) in Mexico: the first database of records

The synthesis of comprehensive databases on the identity and distributions of alien organisms is a critical step to developing informed invasion management plans and identifying areas that are data-deficient. Here, we assembled all available records of alien ant distributions for Mexico, based on the literature, databases and unpublished data for a period ranging from 1855 to 2019; we compiled 967 records for 42 ant species non-native to Mexico, distributed across 438 localities. For the first time, we present mapped records and the distribution database of alien ants which is available through The Global Ant Biodiversity Informatics database at www.antmaps.org. The most commonly recorded species were Paratrechina longicornis, Monomorium pharaonis and Anoplolepis gracilipes. The states with the most records were Veracruz, Chiapas, Jalisco and Quintana Roo. The alien ants were most frequently encountered in urban areas (372 records) and in deciduous forest habitats (220). We provide summary of their distribution patterns and other related information useful for the control of these species in Mexico.

     

Butterfly community ecology: the influences of habitat type,weather patterns,and dominant species in a temperate ecosystem

We compared variation in butterfly communities across 3 years at six different habitats in a temperate ecosystem near Boulder, Colorado, USA. These habitats were classified by the local Open Space consortium as Grasslands, Tallgrass, Foothills Grasslands, Foothills Riparian, Plains Riparian, and Montane Woodland. Rainfall and temperature varied considerably during these years. We surveyed butterflies using the Pollard‐Yates method of invertebrate sampling and compared abundance, species richness, and diversity across habitats and years. Communities were most influenced by habitat, with all three quantitative measures varying significantly across habitats but only two measures showing variation across years. Among habitats, butterfly abundance was higher in Plains Riparian sites than in Montane Woodland or Grassland sites, though diversity was lowest in Plains Riparian areas. Butterfly species richness was higher in Foothills Riparian sites than it was in all but one other habitat (Tallgrass). Among years, butterfly abundance and species richness were lower during the year of least rainfall and highest temperatures, suggesting a substantial impact of the hot, dry conditions. Across habitats and years, butterfly abundance was consistently high at Plains Riparian and Foothills Riparian sites, and richness and diversity were consistently high in Foothills Riparian areas. These two habitats may be highly suitable for butterflies in this ecosystem, regardless of weather conditions. Generally low abundance and species richness in Montane Woodlands sites, particularly in 2002, suggested low suitability of the habitat to butterflies in this ecosystem, and this may be especially important during drought‐like conditions. Finally, to examine the effect that the presence of the very abundant non‐native species Pieris rapae L. (Lepidoptera: Pieridae) has on these communities, we re‐analyzed the data in the absence of this species. Excluding P. rapae dramatically reduced variation of both butterfly abundance and diversity across habitats, highlighting the importance of considering community membership in analyses like ours.     

Can the extinction of Melitaea britomartis in NW Italy be explained by unfavourable weather? An analysis by Optimal Interpolation

We investigated possible correlations between climate-related factors and butterfly range restrictions by selecting a study case represented by four populations of Melitaea britomartis, which become ‘simultaneously’ extinct in NW Italy in 1976–1977 without any observable habitat change. To overcome difficulties related to the analysis of past extinctions and hypothesise causal factors, we applied the Optimal Interpolation method, a statistical method used to create a gridded climatological analysis of temperature and precipitation data, to a historical dataset containing all available information on the Italian butterfly fauna. We tested two different hypotheses: (1) the role of climate change, expressed as a general trend in temperature and precipitation data; (2) the role of extreme weather events, expressed as anomalous conditions during the years of extinctions. Our results show that long-term temperature and precipitation data do not present any clear trend at our study site, suggesting that they cannot be involved in the species’ extinction. On the opposite, 1976 and 1977 were climatologically critical for the study area. In particular, 1977 was characterized by the coldest summer in the entire historical dataset (1958–1977), with strong negative temperature anomalies. Moreover, both years experienced unusually many rainy days during spring and summer. The year 1977 in particular, was the wettest within the entire historical dataset. The years of M. britomartis populations’ extinction were characterised by many more cold and rainy days than usual during the species’ flight period. These results allow us to hypothesize a strong component of unfavourable weather in driving populations’ extinction.     

Chronosequential change in a butterfly community after clear-cutting of deciduous forests in a cool temperate region of central Japan

Transect counts of butterflies were conducted in the northern part of Ibaraki, central Japan, from 1997 to 2001 at 11 census sites, composed of successive stages of deciduous forest development: grassland (one site, early abandoned stage); cutover land (one site, 1–5 years after clear‐cutting); secondary forests (very young (two sites, 6–9 years), middle (two sites, 16–22 years) and old (two sites, 47–51 years)) and old‐growth natural forests (three sites, ≥124 years old). A total of 86 species and 8858 individual butterflies were recorded by 29 sets (406 times) of transect counts. The species richness (number of species), abundance (number of individuals) and diversity indices (Shannon–Wiener H′ and Simpson's 1–λ) of butterflies were high in the early stages (grassland, cutover land and very young secondary forests) of secondary succession. Typical natural forest species increased with the progress of succession, and the old secondary forests and old‐growth natural forests had similar species composition. In contrast, most of the typical natural grassland species were recorded only in the grassland site. In the cutover land site, the number of individuals of grassland species considerably decreased from the first to the second year; furthermore, only one typical natural grassland species was recorded. Thus, the suitable stage for grassland butterfly species lasts for only 1–2 years after clear‐cutting. Old secondary forests (approximately>50 years old) would be able to give refuge to the forest butterfly species, including typical natural forest species. Based on the results, a practical, forestry‐based plan to conserve butterfly diversity was proposed.     

Reproduction of northern spotted owls: The role of local weather and regional climate

We examined associations between annual reproduction and climate for 6 populations of individually marked northern spotted owls (Strix occidentalis caurina) in Washington and Oregon. We used an information-theoretical approach and mixed models to evaluate statistical models representing a priori hypotheses about the effects of weather and climate on reproduction. Reproduction was higher for adult than subadult owls and declined as the proportion of spotted owl territories with barred owl (Strix varia) detections increased. Similar to other spotted owl studies, we found that reproduction was negatively associated with cold, wet winters and nesting seasons at 3 of 6 study areas. In addition, we identified new relationships between reproduction, annual precipitation, storms, and regional climate cycles. For 3 of 6 areas, we found a quadratic relation between precipitation (rain and snow) and reproduction, with the number of young fledged per pair per year declining as precipitation in the previous year deviated from average levels. A meta-analysis conducted across all 6 areas indicated that reproduction at the regional level had a quadratic association with total winter snowfall in the preceding winter and was positively related to temperatures during the previous summer and fall. The amount of annual variation in reproduction accounted for by weather and climate varied widely across the 6 areas (4–79%), whereas variation in weather and climate across owl territories accounted for little of the spatial variation in reproduction (0–4%). Our results suggest that across the range of the species climate factors affecting prey abundance may have a greater effect on reproduction than direct effects of weather on nestlings. © 2011 The Wildlife Society.     

How does landscape context contribute to effects of habitat fragmentation on diversity and population density of butterflies?

Aim Studies on habitat fragmentation of insect communities mostly ignore the impact of the surrounding landscape matrix and treat all species equally. In our study, on habitat fragmentation and the importance of landscape context, we expected that habitat specialists are more affected by area and isolation, and habitat generalists more by landscape context. Location and methods The study was conducted in the vicinity of the city of Göttingen in Germany in the year 2000. We analysed butterfly communities by transect counts on thirty‐two calcareous grasslands differing in size (0.03–5.14 ha), isolation index (2100–86,000/edge‐to‐edge distance 55–1894 m), and landscape diversity (Shannon–Wiener: 0.09–1.56), which is correlated to percentage grassland in the landscape. Results A total of 15,185 butterfly specimens belonging to fifty‐four species are recorded. In multiple regression analysis, the number of habitat specialist (n = 20) and habitat generalist (n = 34) butterfly species increased with habitat area, but z‐values (slopes) of the species–area relationships for specialists (z = 0.399) were significantly steeper compared with generalists (z = 0.096). Generalists, but not specialists, showed a marginally significant increase with landscape diversity. Effects of landscape diversity were scale‐dependent and significant only at the smallest scale (landscape context within a 250 m radius around the habitat). Habitat isolation was not related to specialist and generalist species numbers. In multiple regression analysis the density of specialists increased significantly with habitat area, whereas generalist density increased only marginally. Habitat isolation and landscape diversity did not show any effects. Main conclusions Habitat area was the most important predictor of butterfly community structure and influenced habitat specialists more than habitat generalists. In contrast to our expectations, habitat isolation had no effect as most butterflies could cope with the degree of isolation in our study region. Landscape diversity appeared to be important for generalist butterflies only.     

The use of weather data and counts of aphids in the field to predict the incidence of yellowing viruses of sugar-beet crops in England in relation to the use of insecticides

Partial regression equations were calculated that relate the mean percentage of plants infected with yellowing viruses (beet yellows and beet mild yellowing viruses) in sugar-beet crops at the end of August to the number of days during January, February and March when temperatures fell below – 0.3 °C (31-5 °F) and the mean temperatures in April, for the 21 yr, 1951–71, using weather records from Rothamsted Experimental Station. Regression analyses were also made to find the effect of other factors including mean and minimum temperatures for the same months, and also mean counts of ‘green aphids’, mainly of the vector Myzus persicae, on sugar-beet plants during May and June. Significant relationships were established with all factors, but ‘frost-days’ and April mean temperatures accounted for the greatest percentage of the variance in yellows incidence. The calculations were made separately for the years from 1951 to 1958, when no routine advice was given to farmers about aphid control, and 1959–71 when a ‘spray-warning scheme’ was in operation, and many crops were sprayed at critical times to prevent aphid- and virus-spread. Weather factors had the same effects in both periods, but for any particular weather less virus was spread in the second period than in the first, although there were sufficient aphids, i.e. the numbers expected from the prevailing weather conditions. There was no evidence that insecticide treatment used in any one year affected aphid-incidence in subsequent years. Regression analyses on weather variables were also calculated separately for each of seventeen beet-sugar factory collection-areas, using weather records from local weather stations, and also the Rothamsted weather records. Unexpectedly, the fit of the regressions was always better with Rothamsted weather data than with local weather records. Mean yellows-incidence for the different factory areas declined from south to north, and there was a linear relationship with the square root of the latitude above 50 °C. At the same time the correlation coefficients relating yellows-incidence to ‘frost-days’ became smaller and less significant, and those showing dependence     

广西植物新资料

广西涠洲岛是中国第一大火山岛,现为国家级海洋公园。经过两次的实地调查,采集到标本共348号。整理后发现:2个新记录属,即细穗草属(Lepturus)和蒭雷草属(Thuarea);6个新记录种,即疏花木蓝(Indigofera colutea)、滨豇豆(Vigna marina)、留萼木(Blachia pentzii)、滨海白绒草(Leucas chinensis)、细穗草(Lepturus repens)、蒭雷草(Thuarea involuta)。这些都是适应沿海生境的种类。这些新记录种的发现不仅丰富了广西的植物多样性资料,而且为沿海地区的生态修复提供了参考。     

Inclusion of soil data improves the performance of bioclimatic envelope models for insect species distributions in temperate Europe

Aim To analyse the effect of the inclusion of soil and land‐cover data on the performance of bioclimatic envelope models for the regional‐scale prediction of butterfly (Rhopalocera) and grasshopper (Orthoptera) distributions. Location Temperate Europe (Belgium). Methods Distributional data were extracted from butterfly and grasshopper atlases at a resolution of 5 km for the period 1991–2006 in Belgium. For each group separately, the well‐surveyed squares (n = 366 for butterflies and n = 322 for grasshoppers) were identified using an environmental stratification design and were randomly divided into calibration (70%) and evaluation (30%) datasets. Generalized additive models were applied to the calibration dataset to estimate occurrence probabilities for 63 butterfly and 33 grasshopper species, as a function of: (1) climate, (2) climate and land‐cover, (3) climate and soil, and (4) climate, land‐cover and soil variables. Models were evaluated as: (1) the amount of explained deviance in the calibration dataset, (2) Akaike’s information criterion, and (3) the number of omission and commission errors in the evaluation dataset. Results Information on broad land‐cover classes or predominant soil types led to similar improvements in the performance relative to the climate‐only models for both taxonomic groups. In addition, the joint inclusion of land‐cover and soil variables in the models provided predictions that fitted more closely to the species distributions than the predictions obtained from bioclimatic models incorporating only land‐cover or only soil variables. The combined models exhibited higher discrimination ability between the presence and absence of species in the evaluation dataset. Main conclusions These results draw attention to the importance of soil data for species distribution models at regional scales of analysis. The combined inclusion of land‐cover and soil data in the models makes it possible to identify areas with suitable climatic conditions but unsuitable combinations of vegetation and soil types. While contingent on the species, the results indicate the need to consider soil information in regional‐scale species–climate impact models, particularly when predicting future range shifts of species under climate change.     

Pollination specialization and time of pollination on a tropical Venezuelan plain: variations in time and space

Levels of specialization of the pollination systems were evaluated in 155 plant species from the Venezuelan Central Plain. In all, 29 pollination systems were found, resulting from various combinations of nine pollen‐vector types or pollinating agent classes. The number of pollen‐vector types composing a pollination system ranged from one to five. Ninety‐one species were pollinated by only a single pollen‐vector type; the frequency of pollination systems fell monotonically with increasing number of constituent pollen‐vector types. Some 30–40 per cent of bee‐, moth‐, beetle‐ and bat‐pollinated species were pollinated by that group of vectors alone. The highest incidence of co‐occurrence between pollen‐vector types was found for the combinations fly–wasp, butterfly–wasp, butterfly–fly, and to a lesser extent bird–butterfly, bat–bird, bat–moth and butterfly–moth. The average number of pollen‐vector types per plant species was significantly higher for trees and shrubs than for lianas and perennial herbs. The distribution of polyphily, oligophily, monophily and anemophily was significantly associated with life form and habitat. The relative frequencies of these types varied least through the year in the forest‐savannah ecotone and in the vegetation as a whole, reflecting the combination of life forms. There were significantly fewer night‐pollinated than day‐pollinated species. Day‐pollinated species tended to be polyphilous, and most of the night‐pollinated species were monophilous or oligophilous. Time of pollination activity was related to habitat. The relative importance of night pollination among life forms decreased from trees to perennial herbs. Plant species exclusively pollinated during the night reached a peak during the rainy season (May to November) for trees, lianas and perennial herbs. The data as a whole show that the relative frequency of polyphily, oligophily, monophily and anemophily, and the time of pollination activity are influenced by community structure and plant species richness, and may change from season to season. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 145 , 1–16.     

Early succession of butterfly and plant communities on set-aside fields

 Hypotheses on secondary succession of butterfly and plant communities were tested using naturally developed 1- to 4-year-old set-aside fields (n = 16), sown fields (n = 8) and old meadows (n = 4) in 1992 in South Germany. Pioneer successional fields (1st and 2nd year of succession, dominated by annuals) and early successional fields (3rd and 4th year of succession where perennials, especially grasses became dominant) had fewer plant species than mid-successional fields (old meadows). In contrast to established hypotheses, mean number of plant species decreased from 1- to 4-year-old set-aside fields. Species richness of butterfly communities did not change during the first four years of succession, but species composition changed greatly. Pioneer successional fields were characterized by (1) specialized butterflies depending on annual pioneer foodplants (e.g. Issoria lathonia), and (2) species preferring the pioneer successions despite their host plants being more abundant on early and mid-successional fields (e.g. Papilio machaon). The variability in butterfly species richness was best explained by flower abundance which was closely correlated with plant species richness. Species whose abundance was correlated with habitat connectivity were significantly smaller than species which correlated with flower abundance. Numbers of caterpillar species were correlated with numbers of adult butterfly species. Life-history features of butterflies changed significantly from pioneer to early and mid-successional fields. We found decreasing body size and migrational ability, decreasing numbers of species hibernating as imago, decreasing numbers of generations and increasing larval stage duration with age of succession, but, contrary to expectation, host plant specialization, numbers of egg-cluster laying species and egg diameter did not change with successional age. Received 18 September 1995 / Accepted: 17 July 1996     

An evaluation of self‐reported mobile phone use compared to billing records among a group of engineers and scientists

Most epidemiologic studies of potential health impacts of mobile phones rely on self‐reported information, which can lead to exposure misclassification. We compared self‐reported questionnaire data among 60 participants, and phone billing records over a 3‐year period (2002–2004). Phone usage information was compared by the calculation of the mean and median number of calls and duration of use, as well as correlation coefficients and associated P‐values. Average call duration from self‐reports was slightly lower than billing records (2.1 min vs. 2.8 min, P = 0.01). Participants reported a higher number of average daily calls than billing records (7.9 vs. 4.1, P = 0.002). Correlation coefficients for average minutes per day of mobile phone use and average number of calls per day were relatively high (R = 0.71 and 0.69, respectively, P < 0.001). Information reported at the monthly level tended to be more accurate than estimates of weekly or daily use. Our findings of modest correlations between self‐reported mobile phone usage and billing records and substantial variability in recall are consistent with previous studies. However, the direction of over‐ and under‐reporting was not consistent with previous research. We did not observe increased variability over longer periods of recall or a pattern of lower accuracy among older age groups compared with younger groups. Study limitations included a relatively small sample size, low participation rates, and potential limited generalizability. The variability within studies and non‐uniformity across studies indicates that estimation of the frequency and duration of phone use by questionnaires should be supplemented with subscriber records whenever practical. Bioelectromagnetics 32:37–48, 2011. © 2010 Wiley‐Liss, Inc.     

Determinants of foraging profitability in two nectarivorous butterflies

ABSTRACT.

• 1 I studied flower selection and foraging energetics of Agraulis vanillae L. (Nymphalidae) and Phoebis sennae (Pieridae), two butterfly species common to north central Florida. I identified the major nectar resources exploited by several populations of these butterflies and, for each plant species, measured available nectar volumes and concentrations, corolla lengths, and density. I quantified foraging behaviour of each butterfly species at each nectar source (flower visitation rate and percentage of foraging time in flight), and used these data to estimate the net rate of energy intake of each butterfly species at each nectar source.
• 2 Estimated mean energy contents of individual flowers of the eleven exploited plant species spanned three orders of magnitude, ranging between 0.015 and 9.27 joules. Mean energy content of individual flowers was strongly correlated with mean foraging profit of both butterfly species.
• 3 Mean nectar volume strongly influenced energy content and varied widely within and among species, ranging from 0.0076 to 1.853 μ1. Nectar concentration varied between 17.1% and 40.4% sucrose-equivalents. Nectar volume was the best single predictor of foraging profitability (correlation coefficients of 0.994 and 0.984 for Phoebis and Agraulis respectively). Corolla length also strongly affected foraging profitability for both butterfly species; flower species with longer corollas were generally more profitable.
• 4 Flower density and nectar concentration showed weak or nonsignificant associations with foraging profitability.
• 5 The usefulness and limitations of these floral characteristics as bases for foraging selectivity, and the selective pressures foraging butterflies might place on the visited plants are discussed.