Differential long-term impacts of a management control program of axis deer and wild boar in a protected area of north-eastern Argentina

Exotic ungulates are among the top global invasive mammals and a threat to biodiversity. Axis deer (Axis axis) and wild boar (Sus scrofa) are of increasing concern in multiple regions. A management program reduced wild boar abundance and soil damage below target levels through controlled still shooting from watchtowers and dog-hunting performed by recreational hunters at El Palmar National Park, Argentina. Here we assess program impacts on axis deer over a 10-year period in which 2380 deer were dispatched, and document two largely unexpected outcomes: increasing axis deer abundance toward a plateau, and a strong inverse correlation between deer and wild boar numbers. Unlike the initial steep decline and subsequent stabilization of wild boar, deer abundance indexed by standardized catch-per-unit-effort increased at 37.6% per year over 0–5 years post-intervention (YPI) and stabilized from 7 YPI on when still-shooting effort averaged 948 hunting party-hours per quarter. Deer catch was non-linearly related to still-shooting effort. Timing of deer and boar catches did not differ significantly regardless of sex, season and YPI. Catch-per-unit-effort indices and nightly spotlight deer counts showed similarly increasing trends. The fraction of older adult deer declined over 0–4 YPI and remained stable thereafter. Sex ratios were consistently skewed toward males only among older adults. Failure to reduce deer abundance may be explained by several major processes: protracted exponential growth of the deer population after park invasion; deer regional expansion with increasing immigration; insufficient sex- and stage-biased hunting mortality, and competitor (and perhaps predator) release from wild boar.     

Sensitivity of wild and genetic sexing strain Ceratitis capitata to high-temperature disinfestation of Valencia oranges

Abstract:  The purpose of this research was to investigate post-harvest heat treatment of Valencia oranges as an effective disinfestation protocol (fast, no fruit damage) for the Mediterranean fruit fly Ceratitis capitata (Wiedemann). Forced high-temperature air was applied under the following conditions: (a) exposure to air temperature of 56°C, for fast increase of temperature in the interior of the fruit, (b) reduction in air temperature to 47°C when the fruit centre reached 47°C and (c) maintenance of fruits in the chamber for another 30 min. Relative humidity in the treatment chamber was kept between 50% and 65% during treatment. Forced air at 47°C applied for 30 min on eggs before hatch or late third instar larvae (the most heat-tolerant stages) resulted in complete kill. Egg and larval sensitivity to high temperature differed between a wild strain and a laboratory genetic-sexing strain based on white pupa mutation. In this strain males emerge from brown pupae and females from white pupae. In particular, mature eggs from the wild strain were significantly more temperature resistant than eggs from the laboratory strain. Exposure of Valencia oranges of a diameter of 7–7.5 cm to 56°C forced air for about 86 and 99 min was required to increase temperature to 47°C at 1.5 cm depth and the fruit centre respectively. Treated oranges showed no substantial peel or interior deterioration, or change in colour and taste when kept at 25°C and 50–60% RH for a period of up to 1 month following treatment. Treatment in 1% O₂ atmosphere, produced by flushing of CO₂ into the treatment chamber, resulted in about 1°C reduction in killing temperature and faster increase in temperature inside the fruit to a lethal level.     

Facilitative and competitive interactions between sympatric cattle, red deer and wild boar in Dutch woodland pastures

Use of cattle-grazed and ungrazed woodland pastures by red deerCervus elaphus Linnaeus, 1758 and wild boarSus scrofa Linnaeus, 1758 was investigated monthly by measuring dung-deposition rates. CattleBos taurus grazed pastures year-round, with peak intensities during the growing season (May–September). Red deer and wild boar grazed pastures primarily during autumn and winter (October–April) when cattle occupancy was at a minimum. The lower occupancy of cattle in pastures from November to April was interpreted as the result of competition with red deer. Mean sward height in this period fell below 6.5 cm. In autumn and winter a negative relationship was found for red deer and wild boar occupancy with sward height, which indicated that red deer and wild boar preferred swards previously grazed by cattle. At the start of the growing season, when cattle occupancy in the pastures increased, red deer switched their habitat preference and almost totally disappeared from pastures to use alternative feeding grounds. Interpretation of the results lead to the conclusion that facilitative and competitive interactions occurred between sympatric cattle and red deer in woodland pastures, and to some extent also between cattle and wild boar.     

Natural thermal stress and heat-shock protein expression in Drosophila larvae and pupae

1. Whether Drosophila larvae and pupae naturally experience temperatures that can cause heat damage or death is poorly understood, but bears directly on numerous investigations of the thermal biology and heat-shock response in Drosophila . Accordingly, the temperatures of necrotic fruit, which Drosophila larvae and pupae inhabit, the temperatures of larvae and pupae outside the laboratory, and the levels of the heat-shock protein hsp 70 expressed by larvae in nature were examined.
2. When necrotic fruit was sunlit, internal temperatures rose to levels that can harm indwelling insects. Fruit size and evaporative water loss affected these temperatures. Temperatures of larvae and pupae in the field commonly exceeded 35 °C, with living larvae recorded at >44°C and pupae at >41°C. Natural mortality was evident, presumably because of heat.
3. In the laboratory, these temperatures kill larvae rapidly, with LT₅₀s (time taken for half the sample to be killed) of 30 min at 39 °C, 15 min at 40 °C and 8·5 min at 41 °C. Gradual transfer from 25°C to these temperatures resulted in no lesser mortality than did direct transfer.
4. Hsp 70 levels in lysates of whole larvae were measured by ELISA (enzyme-link immunosorbent assay) with an hsp 70-specific antibody. For larvae within necrotic apples experimentally transferred from shade to sun and within necrotic fruit in situ , hsp 70 levels equalled or exceeded levels detected in parallel laboratory studies of whole larvae or cells in culture.
5. These data provide an ecological context for studies of thermal stress and the heat-shock response in Drosophila that has heretofore been lacking.     

Combined evaluation of bovine tuberculosis in wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis>) and red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) from Central-East Portugal

Bovine tuberculosis (bTB), widely considered a disease of livestock, can also affect large game species despite their poorly understood role in the epidemiology of the endemic state of the disease. The Idanha-a-Nova County, situated in the eastern region of central Portugal, is one of the most important regions for large game hunting activity. In order to investigate the role of large game and the presence of bTB in Idanha-a-Nova, 132 wild boar (Sus scrofa) and 339 red deer (Cervus elaphus) were inspected for bTB-compatible lesions (bTBCL) during the 2008–2009 hunting season. Tissue samples with bTBCL were collected and processed for bacteriological confirmation and spoligotyping of Mycobacterium bovis isolates. In wild boar, bTB lesions were single, mostly calcified (21/29, 72.4%) and situated in the mandibular lymph nodes. Lesions were more severe and largely non-calcified (36/40, 90%) in red deer. Wild boar presented a consistently higher bTB infection rate than the red deer; however, the difference was only significant in the southern B area. This area was significantly affected by bTB for both animal species (up to 72.7% in wild boar and 34.8% in red deer) and requires the urgent implementation of intervention measures to contain the disease. Wild boar may assume an important role in the emergence of new disease foci in distant areas that infected red deer cannot reach. Spoligotyping of M. bovis isolates grouped the strains into three clusters, revealing patterns common to wild boar, red deer, and also to local cattle, indicating possible transmission among different animal species.     

Bovine tuberculosis in Doñana Biosphere Reserve: the role of wild ungulates as disease reservoirs in the last Iberian lynx strongholds

Doñana National Park (DNP) in southern Spain is a UNESCO Biosphere Reserve where commercial hunting and wildlife artificial feeding do not take place and traditional cattle husbandry still exists. Herein, we hypothesized that Mycobacterium bovis infection prevalence in wild ungulates will depend on host ecology and that variation in prevalence will reflect variation in the interaction between hosts and environmental risk factors. Cattle bTB reactor rates increased in DNP despite compulsory testing and culling of infected animals. In this study, 124 European wild boar, 95 red deer, and 97 fallow deer were sampled from April 2006 to April 2007 and analyzed for M. bovis infection. Modelling and GIS were used to identify risk factors and intra and inter-species relationships. Infection with M. bovis was confirmed in 65 (52.4%) wild boar, 26 (27.4%) red deer and 18 (18.5%) fallow deer. In the absence of cattle, wild boar M. bovis prevalence reached 92.3% in the northern third of DNP. Wild boar showed more than twice prevalence than that in deer (p<0.001). Modelling revealed that M. bovis prevalence decreased from North to South in wild boar (p<0.001) and red deer (p<0.01), whereas no spatial pattern was evidenced for fallow deer. Infection risk in wild boar was dependent on wild boar M. bovis prevalence in the buffer area containing interacting individuals (p<0.01). The prevalence recorded in this study is among the highest reported in wildlife. Remarkably, this high prevalence occurs in the absence of wildlife artificial feeding, suggesting that a feeding ban alone would have a limited effect on wildlife M. bovis prevalence. In DNP, M. bovis transmission may occur predominantly at the intra-species level due to ecological, behavioural and epidemiological factors. The results of this study allow inferring conclusions on epidemiological bTB risk factors in Mediterranean habitats that are not managed for hunting purposes. Our results support the need to consider wildlife species for the control of bTB in cattle and strongly suggest that bTB may affect animal welfare and conservation.     

Prey selection and dietary response by wolves in a high-density multi-species ungulate community

Studies on predation by the wolf (Canis lupus) have often reported contradictory results about the role of prey density and vulnerability on wolf prey use. We investigated dietary response and prey selection by wolves in a high-density and multi-species ungulate community, analysing scats collected over a period of 11 years in the Casentinesi Forests, Italy. The second most abundant species, wild boar (Sus scrofa), was found to be the main wolf prey, and we did not observe any dietary response of wolves to variations in the density of either primary or secondary prey species. Selection patterns were uniform throughout the study period. Wolves strongly selected for wild boar piglets, while roe deer (Capreolus capreolus) fawns and adults, red deer (Cervus elaphus) adults and fallow deer (Dama dama) adults were avoided. Wolf preference for wild boar was inversely density dependent. Within each species, juveniles were preferred to adults. Medium-sized, young individuals of both wild boar and roe deer were optimal prey, although with different selection patterns related to the different anti-predator strategies adopted by each prey species. The results of this study suggest that in productive ecosystems with high density and high renewal rates of prey, selection patterns by wolves are determined by prey vulnerability, which is connected to prey age and body size. The different patterns of wild boar versus cervids use by wolf across Europe seems to be related to their relative abundances, while the strong selection of wild boar in Italian Apennines with respect to the more frequent avoidance in central-eastern Europe is better explained by higher piglet productivity and smaller body size of adults boar in Mediterranean temperate forests.     

同域分布的野猪与狍活动节律及与月光周期的关系

完全的竞争者不能共存,物种间生态位分化是同域物种长期稳定共存的基础。不同物种在同一分布区时间生态位的分化对其共存至关重要。为研究同域分布物种的共存机制,在2018年11月到2021年7月利用远红外相机监测技术对穆棱东北红豆杉国家级自然保护区同域分布的野猪(Sus scrofa)和狍(Capreolus pygargus)进行了野外监测研究,并利用核密度估计方法和雅各布斯选择指数(JSI)对日活动节律和一段时间内的活动周期选择进行了评估,同时还利用非参数检验评估了2个物种的活动与月光周期的关系。研究结果表明,狍不管在全年还是在不同的季节,日活动节律均为双峰模式,而野猪的活动模式表现出明显的可塑性,在全年和冷季为单峰型,暖季为双峰型,二者在日活动节律上的重叠程度较高(Dhat>0.59),在暖季的重叠系数最高(Dhat=0.65)。此外,在时间段的选择上,狍在全年和冷季更喜欢在黎明和黄昏活动(0.170.32),而野猪活动在全年和冷季对白天和黄昏的选择更多(JSI>0.3),暖季则更喜欢在白天活动(J...     

东北虎豹国家公园东部的野猪生境利用和活动节律初步研究

野猪是世界上分布最广的大型哺乳动物之一,也是东北虎豹国家公园内主要的有蹄类动物,东北虎主要的猎物之一。本文采集了中国虎豹观测网络架设在东北虎豹国家公园东部区域的红外相机完整一年的拍摄数据（2015年5月至2016年4月）,通过占域模型和核密度分析,获得不同季节的野猪生境利用情况和日活动节律,探究人为因素、环境因素和生物因素对野猪生境利用的影响。结果显示,野猪偏好于针叶林和针阔混交林,在靠近居民点的区域活动增加。不同物种间的相互作用对野猪的生境利用产生不同影响,受捕食者压力野猪会倾向于躲避东北虎,但东北豹对野猪占域显示为正向影响。梅花鹿和狍对野猪的影响在不同季节呈现相反,梅花鹿对野猪的占域在冬季呈负向影响,而狍对野猪的占域则在夏季呈负向影响。本研究区域内的野猪夏季有2个活动高峰,冬季有1个活动高峰,在不同季节都倾向于白天和晨昏活动,在日落前达到活动最高峰。本研究揭示东北虎豹国家公园东部区域的野猪生境利用和活动节律是受到植被生境、大型食肉动物和人类因素等多种因素相互作用,长期相适应的结果。     

Wolf predation and snow cover as mortality factors in the ungulate community of the Bialowieża National Park,Poland

Summary Wolf-ungulate interactions were studied in the pristine deciduous and mixed forests of the Bialowiea National Park in 1985–1989. The study period included two severe and two mild winters. The community of ungulates inhabiting Bialowiea National Park consisted of red deer Cervus elaphus, 55% of all ungulates; wild boar Sus scrofa, 42%; and roe deer Capreolus capreolus, moose Alces alces, and European bison Bison bonasus, about 1% each. The average size of red deer groups increased from 2.7 (SD 2.35) in spring and summer to 6.9 (SD 6.84) in autumn and winter. In winter the group size of red deer was positively correlated with the depth of snow cover and negatively correlated with the mean daily temperature. Average group size of wild boar did not change significantly between seasons; it was 6.8 (SD 5.16) in spring and summer and 5.7 (SD 4.67) in autumn and winter. Analysis of 144 wolf scats showed that wolves preyed selectively on red deer. In October–April, Cervidae (mostly red deer) constituted 91% of biomass consumed by wolves, while wild boar made up only 8%. In May–September deer formed 77% of prey biomass, and the share of wild boar increased to 22%. In all seasons of the year wolves selected juveniles from deer and boar populations: 61% of red deer and 94% of wild boar of determined age recovered from wolves' scats were young <1 year old. Analysis of 117 carcasses of ungulates found in Bialowiea National Park showed that predation was the predominant mortality factor for red deer (40 killed, 10 dead from causes other than predation) and roe deer (4 killed, none dead). Wild boar suffered most from severe winter conditions (8 killed, 56 dead). The percentage of ungulates that had died from undernutrition and starvation in the total mortality was proportional to the severity of winter.     

Comparing red deer (Cervus elaphus L.) and wild boar (Sus scrofa L.) dispersal patterns in southern Belgium

This study analyses the natal dispersal of red deer and wild boar in order to compare their dispersal capabilities in southern Belgium and to evaluate the relevance of management unit areas (MUA) designed for their monitoring. Dispersal was studied thanks to a mark-recovery method based on 111 red deer fawns and 1,613 piglets. The recovery rate of ear-tagged animals was 68 and 40 %, respectively. In both species, sub-adult males moved on longer distances ( $ \mathop{x}\limits^{-} $ red deer?=?4.82+/?4.17 km and $ \mathop{x}\limits^{-} $ wild boar?=?4.90+/?5.65 km) than females and juveniles $ \mathop{x}\limits^{-} $ (red deer?=?1.84+/?1.46 km and $ \mathop{x}\limits^{-} $ wild boar?=?2.49+/?3.74 km). Taking into account the age and sex categories, we found no difference between species in dispersal mean distance. But we observed higher maximal dispersal distances in wild boar compared to red deer. The natal home range mean sizes were 5.29 km² (+/?4.87) for red deer and 6.23 km² (+/?4.60) for wild boar. Red deer and wild boar showed similar dispersal rates according to age and sex category: 53 and 42 % in sub-adult males and 14 and 16 % in females and juveniles. Our results confirmed the higher proportion of philopatry in females and juveniles of both species compared to sub-adult males more likely to disperse. Wild boar of any sex or age seemed to be less sensitive than red deer to infrastructure (road, rail, river) network on which the management unit area limits are currently based.     

Delayed egg production and a possible group effect in the blowfly Calliphora vicina

Abstract .Protein-fed Calliphora vicina , F₁ offspring of wild flies in two cages with lower and higher fly densities showed variable delay in starting oocyte vitellogenesis at ambient semi-natural temperatures in warm July–August weather in 1996 and 1997 at Durham in northern England (54°45' N). The high-density flies in 1996 showed no delay, in that the thermal sum (degree-days) experienced was 133, comparable to 18°C constant, assuming the lower threshold for egg maturation to be 5°C. Low-density cages and flies in a large outdoor cage (2 m³) in both years showed delays in production of first eggs of 34 days (thermal sum 293 degree-days) in 1996 and 32 days (396 degree-days) in 1997, and longer delays for other individuals. Delays in egg production at low densities relative to high densities seem to be a group effect of unknown mechanism.     

Heat inactivation of electron transport reactions in photosystem II particles

Heat inactivation of diphenylcarbazide (DPC)-supported 2,6-dichloroindophenol (DCIP) photoreduction by photosystem II (PS II) particles and non-oxygen-evolving PS II core complex isolated from spinach ( Spinacia oleracea L. cv. Kyoho) was suppressed under annealing conditions, and accelerated in the presence of EDTA or high concentration of divalent cations. After heating at 45°C for 10 min, half-maximal annealing effects occurred at 35°C. Minimum acceleration was observed in the presence of 1 m M Mg²⁺, implying the existence of a cation-specific site in the vicinity of the PS II reaction center. The acceleration depended on the temperature at which EDTA was added to PS II particles. Half-acceleration by EDTA occurred at 35°C. Glutaraldehyde stabilized PS II particles against heat inactivation of PS II photochemical reactions.     

Do exotic pine plantations favour the spread of invasive herbivorous mammals in Patagonia?

Changes in land use patterns and vegetation can trigger ecological change in occupancy and community composition. Among the potential ecological consequences of land use change is altered susceptibility to occupancy by invasive species. We investigated the responses of three introduced mammals (red deer, Cervus elaphus; wild boar, Sus scrofa; and European hare, Lepus europaeus) to replacement of native vegetation by exotic pine plantations in the Patagonian forest‐steppe ecotone using camera‐trap surveys (8633 trap‐days). We used logistic regression models to relate species presence with habitat variables at stand and landscape scales. Red deer and wild boar used pine plantations significantly more frequently than native vegetation. In contrast, occurrence of European hares did not differ between pine plantations and native vegetation, although hares were recorded more frequently in firebreaks than in plantations or native vegetation. Presence of red deer and wild boar was positively associated with cover of pine plantations at the landscape scale, and negatively associated with mid‐storey cover and diversity at the stand scale. European hares preferred sites with low arboreal and mid‐storey cover. Our results suggest that pine plantations promote increased abundances of invasive species whose original distributions are associated with woodlands (red deer and wild boar), and could act as source or pathways for invasive species to new areas.     

The body size of wild boar during the Mesolithic in southern Scandinavia

In order to study the body size of wild boarSus scrofa Linnaeus, 1758 during the Boreal and Atlantic Chronozones in southern Scandinavia, 12 measurements of teeth and bones from 32 Mesolithic sites from Scania (Sweden) and Zealand and Jutland (Denmark) were analysed. The osteometric analysis revealed that the body size of wild boar from Scania did not change during the period. The results indicate that the changes of ecological conditions during the transition from the Boreal to the Atlantic chronozones did not affect wild boar in the same way as red deer and roe deer, which decreased in body size during the period. The tooth size of wild boar from Zealand is smaller than in wild boar from Jutland and Scania during the Late Atlantic Chronozones, which probably is the result of the isolation of the population when Zealand became an island. Calculations of withers height show that wild boar in southern Scandinavia during the Atlantic Chronozones were of similar body size as recent wild boar from eastern Europe.     

Inter-specific synchrony of two contrasting ungulates: wild boar (Sus scrofa) and roe deer (Capreolus capreolus)

Very few studies on ungulates address issues of inter-specific synchrony in population responses to environmental variation such as climate. Depending on whether annual variation in performance of ungulate populations is driven by direct or indirect (trophic) interactions, very different predictions regarding the pattern of inter-specific synchrony can be derived. We compared annual autumn body mass variation in roe deer (Capreolus capreolus) and wild boar (Sus scrofa) from Poland over the period 1982–2002, and related this to variation in winter and summer climate and plant phenological development [the Normalized Difference Vegetation Index (NDVI), derived from satellites]. Roe deer fawns (∼1.3 kg increase from year 1982 to 2002) and yearlings both increased markedly in mass over years. There was also an increase for wild boar mass over years (∼4.2 kg increase for piglets from 1982 to 2002). Despite our failure to link annual body mass to spring or winter conditions or the NDVI, the body mass of roe deer and wild boar fluctuated in synchrony. As this was a field roe deer population, and since wild boar is an omnivore, we suggest this may be linked to annual variation and trends in crop structure (mainly rye). We urge future studies to take advantage of studying multiple species in order to gain further insight into processes of how climate affect ungulate populations. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Developmental variation and amino acid sequences of cytochromes c of the fruit fly Drosophila melanogaster and the flesh fly Boettcherisca peregrina

The amino acid sequences of cytochromes c purified from the fruit fly Drosophila melanogaster and the flesh fly Boettcherisca peregrina were determined. In contrast with the case of the housefly, isocytochromes c were not detected in these flies at any developmental stage. The sequence of fruit fly cytochrome c differed from that reported previously but was identical with that predicted from the nucleotide sequence of the fruit fly cytochrome c gene (DC4) (Limbach, K.J. & Wu, R. (1985) Nucl. Acids Res. 13, 631-644). Isocytochrome c of the fruit fly, reported to be encoded by the DC3 gene, was not detected as a functional cytochrome c molecule.     

Comparative landscape genetic analyses show a Belgian motorway to be a gene flow barrier for red deer (Cervus elaphus), but not wild boars (Sus scrofa)

While motorways are often assumed to influence the movement behaviour of large mammals, there are surprisingly few studies that show an influence of these linear structures on the genetic make-up of wild ungulate populations. Here, we analyse the spatial genetic structure of red deer (Cervus elaphus) and wild boars (Sus scrofa) along a stretch of motorway in the Walloon part of Belgium. Altogether, 876 red deer were genotyped at 13 microsatellite loci, and 325 wild boars at 14 loci. In the case of the red deer, different genetic clustering tools identified two genetic subpopulations whose borders matched the motorway well. Conversely, no genetic structure was identified in the case of the wild boar. Analysis of isolation-by-distance patterns of pairs of individuals on the same side and on different sides of the motorway also suggested that the road was a barrier to red deer, but not to wild boar movement. While telemetry studies seem to confirm that red deer are more affected by motorways than wild boar, the red deer sample size was also much larger than that of the wild boars. We therefore repeated the analysis of genetic structure in the red deer with randomly sub-sampled data sets of decreasing size. The power to detect the genetic structure using clustering methods decreased with decreasing sample size.     

Wolf (Canis lupus) feeding habits during the first eight years of its occurrence in Germany

Due to the fact that the feeding habits of large carnivores are the main contentious point when they start resettling regions they were absent from for several decades, the diet composition of the wolves in Germany was analysed from the beginning of this process. Wolves in Germany primarily feed on wild ungulates, which make up more than 96% of their diet. The dominating prey species is the roe deer (55.3%), followed by red deer (20.8%) and wild boar (17.7%). The second important food category are the leporids (2.9% of Biomass), whereas livestock makes up only 0.6% of all biomass consumed. Wolves clearly prefer hunting on juvenile to adult red deer; roe deer are not selected after their age. We found seasonal differences in the diet composition with a higher amount of wild boar in spring and winter, when a high amount of juveniles and weakened animals, respectively, are available. In the first years of the study the percentage of red deer was much higher, and the percentage of roe deer therefore was lower than the following years. The amount of wild boar in the wolf diet fluctuated most in the first three years. Diet composition remained constant during the last five years. Wolves needed less than two generations for adapting to the new conditions in the cultivated landscape of eastern Germany.     

Impact of scoring error and reproducibility RAPD data on RAPD based estimates of genetic distance

RAPD band reproducibility and scoring error were evaluated for RAPDs generated by 50 RAPD primers among ten snap bean (Phaseolus vulgaris L.) genotypes. Genetic distances based on different sets of RAPD bands were compared to evaluate the impact of scoring error, reproducibility, and differences in relative amplification strength on the reproducibility of RAPD based genetic distance estimates. The measured RAPD data scoring error was 2%. Reproducibility, expressed as the percentage of RAPD bands scored that are also scored in replicate data, was 76%. The results indicate that the probability of a scored RAPD band being scored in replicate data is strongly dependent on the uniformity of amplification conditions between experiments, as well as the relative amplification strength of the RAPD band. Significant improvement in the reproducibility of scored bands and some reduction in scoring error was achieved by reducing differences in reaction conditions between replicates. Observed primer variability for the reproducibility of scored RAPDs may also facilitate the selection of primers, resulting in dramatic improvements in the reproducibility of RAPD data used in germplasm studies. Variance of genetic distances across replicates due to sampling error was found to be more than six times greater than that due to scoring error for a set of 192 RAPD bands. Genetic distance matrices computed from the RAPD bands scored in replicated data and RAPD bands that failed to be scored in replicated data were not significantly different. Differences in the ethidium bromide staining intensity of RAPD bands were not associated with significant differences in resulting genetic distance matrices. The assumption of sampling error as the only source of error was sufficient to account for the observed variation in genetic distance estimates across independent sets of RAPD bands.