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Freshwater macroinvertebrates are a diverse group and play key ecological roles, including accelerating nutrient cycling, filtering water, controlling primary producers, and providing food for predators. Their differences in tolerances and short generation times manifest in rapid community responses to change. Macroinvertebrate community composition is an indicator of water quality. In Europe, efforts to improve water quality following environmental legislation, primarily starting in the 1980s, may have driven a recovery of macroinvertebrate communities. Towards understanding temporal and spatial variation of these organisms, we compiled the TREAM dataset (Time seRies of European freshwAter Macroinvertebrates), consisting of macroinvertebrate community time series from 1,816 river and stream sites (mean length of 19.2 years and 14.9 sampling years) of 22 European countries sampled between 1968 and 2020. In total, the data include >93 million sampled individuals of 2,648 taxa from 959 genera and 212 families. These data can be used to test questions ranging from identifying drivers of the population dynamics of specific taxa to assessing the success of legislative and management restoration efforts. [ABSTRACT FROM AUTHOR]

While our understanding of long-term trends in material wealth inequality in prehistoric societies has expanded in recent decades, we know little about long-term trends in other dimensions of wealth and about social developments within particular societal segments. This paper provides the first evidence of inequality in relational wealth within the upper societal segment of a supra-regional network of communities in prehistoric Central Europe over the first four millennia BCE. To this end, we compiled a novel dataset of 5000 single-funeral burial mounds and employed burial mound volume as a proxy for the buried individual's relational wealth. Our analysis reveals a consistently high level of inequality among the buried individuals, showing a wave-like pattern with an increasing trend over time. Additionally, our findings show temporal shifts in the size of the upper societal segment. Based on a review of archeological and paleo-environmental evidence, the temporal change in inequality may be explained by technological progress, climate and population dynamics, trade and social networks, and/or sociopolitical transformations. [ABSTRACT FROM AUTHOR]

The population abundance of birds is an important way to gauge the sustainability and health of the environment. However, several factors influence their distribution and density in different habitats. This paper aims to provide a comprehensive and updated outlook on bird population dynamics in Europe in the past 40 years. With the use of Generalized Additive Mixed Models (GAMMs), we analyzed the data available from the Pan-European Common Bird Monitoring Scheme (PECBMS) on abundance indexes collected throughout Europe from 1980 to 2019 and explored the driving forces behind our observed changes for each habitat type. We also apply GAMMs to model the overall changes in abundance indices of eight bird species that showed the highest variations (i.e., Locustella fluviatilis, Locustella naevia, Alcedo atthis, Bombycilla garrulus, Tetrax tetrax, Tringa totanus, Anthus campestris and Larus ridibundus). It was noted that the general abundance of birds decreased, with farmland birds suffering the biggest decline. Forest bird species population abundance was found to be quite varied; specialist species decreased as compared to generalists, which generally increased. [ABSTRACT FROM AUTHOR]

Environmental conditions can influence the individual development of organisms and their morphological variability at the population level. The dimensions and proportions of the skull and lower jaw of immature shrews (Sorex araneus, S. caecutiens, and S. minutus), which were captured in August in regenerating clearings in the middle taiga of northeastern Europe, depended on the stage of abundance dynamics ("peaks" or "depressions"). For all three species from the same taxocenosis, a statistically significant reduction in the skull and jaw was observed against the background of the high abundance in captures and the multidimensional morphological niches corresponding to different abundance stages were significantly separated. The parameters of morphological diversity (entropy and self-organization index) depended on the amplitude of fluctuations in species occurrence; however, they varied within the limits characteristic of mammals. Along with Dehnel's phenomenon, natural population fluctuations may be one of the main factors determining the pattern of dynamics of the individual development and spatiotemporal variability of the morphological diversity of shrews. [ABSTRACT FROM AUTHOR]

Regional variability in the spatial distribution of resident population and across-country density divides have consolidated heterogeneous demographic patterns at the base of modern urban systems in Europe. Although economic, historical, institutional, and cultural factors have demonstrated to affect the spatial distribution of resident population, density-dependence and path-dependence are mechanisms persistently shaping demographic dynamics at both local and regional scale. Analysis of density-dependent patterns of population growth (and decline) over sufficiently long time intervals allows a refined comprehension of socioeconomic processes underlying demographic divides. Despite a long settlement history, empirical investigation of the role of density-dependence in the long-term evolution of human populations along urban–rural gradients is relatively scarce especially in Mediterranean countries. The present study performs a comparative analysis of population distribution in 1033 Greek municipalities identifying (and testing the significance of) density-dependent and path-dependent mechanisms of population growth between 1961 and 2011, using spatially implicit and explicit econometric approaches. Results highlight a positive impact of density on population growth where settlements are concentrated. Assuming goodness of fit of the tested models as a proxy of density-dependence, the empirical findings clarify how density-dependent mechanisms were not significant all over the study period, being instead associated with specific phases of the city life cycle—basically urbanization with population concentrating in central locations. Density-dependence was less intense with suburbanization and counter-urbanization—when population sprawled over larger areas at medium–low density. An improved understanding of density-dependent and path-dependent mechanisms of population growth contributes to rethink spatial planning, regional development strategies, and socio-demographic policies adapting to heterogeneous (and rapidly changing) local contexts. [ABSTRACT FROM AUTHOR]

The genomic landscape of Stone Age Europe was shaped by multiple migratory waves and population replacements, but different regions do not all show similar patterns. To refine our understanding of the population dynamics before and after the dawn of the Neolithic, we generated and analyzed genomic sequence data from human remains of 56 individuals from the Mesolithic, Neolithic, and Eneolithic across Central and Eastern Europe. We found that Mesolithic European populations formed a geographically widespread isolation-by-distance zone ranging from Central Europe to Siberia, which was already established 10,000 years ago. We found contrasting patterns of population continuity during the Neolithic transition: people around the lower Dnipro Valley region, Ukraine, showed continuity over 4000 years, from the Mesolithic to the end of the Neolithic, in contrast to almost all other parts of Europe where population turnover drove this cultural change, including vast areas of Central Europe and around the Danube River. Genome-wide sequencing of 56 ancient hunter-gatherer and early farmer individuals from Stone Age Central and Eastern Europe reveals striking population continuity in the east in contrast to central Europe that displays extensive admixture. [ABSTRACT FROM AUTHOR]

Archaeological evidence suggests that the population dynamics of Mid-Holocene (Late Mesolithic to Initial Bronze Age, ca. 7000–3000 BCE) Europe are characterized by recurrent booms and busts of regional settlement and occupation density. These boom-bust patterns are documented in the temporal distribution of 14C dates and in archaeological settlement data from regional studies. We test two competing hypotheses attempting to explain these dynamics: climate forcing and social dynamics leading to inter-group conflict. Using the framework of spatially-explicit agent-based models, we translated these hypotheses into a suite of explicit computational models, derived quantitative predictions for population fluctuations, and compared these predictions to data. We demonstrate that climate variation during the European Mid-Holocene is unable to explain the quantitative features (average periodicities and amplitudes) of observed boom-bust dynamics. In contrast, scenarios with social dynamics encompassing density-dependent conflict produce population patterns with time scales and amplitudes similar to those observed in the data. These results suggest that social processes, including violent conflict, played a crucial role in the shaping of population dynamics of European Mid-Holocene societies. [ABSTRACT FROM AUTHOR]

Population dynamics set the framework for human genetic and cultural evolution. For foragers, demographic and environmental changes correlate strongly, although the causal relations between different environmental variables and human responses through time and space likely varied. Building on the notion of limiting factors, namely that at any one time, the scarcest resource caps population size, we present a statistical approach to identify the dominant climatic constraints for hunter-gatherer population densities and then hindcast their changing dynamics in Europe for the period between 21,000 to 8000 years ago. Limiting factors shifted from temperature-related variables (effective temperature) during the Pleistocene to a regional mosaic of limiting factors in the Holocene dominated by temperature seasonality and annual precipitation. This spatiotemporal variation suggests that hunter-gatherers needed to overcome very different adaptive challenges in different parts of Europe and that these challenges varied over time. The signatures of these changing adaptations may be visible archaeologically. In addition, the spatial disaggregation of limiting factors from the Pleistocene to the Holocene coincided with and may partly explain the diversification of the cultural geography at this time. Here, the authors use climate and resource availability, to statistically model the limiting factors in the dynamics of hunter-gatherer population densities in Europe between 21,000 and 8,000 years ago. They find that limiting factors varied spatiotemporally and the effects of these may be visible in the archaeological record. [ABSTRACT FROM AUTHOR]

The two sibling and syntopic odonate species Sympetrum striolatum and Sympetrum vulgatum are common and widespread in Central Europe. While S. striolatum has strong positive population trends, declines of S. vulgatum are observed. The aim of this study was to identify possible drivers of these diverging trends. We presumed that differences in egg development may lead to differences in survival until hatching. First, eggs laid in non-permanent or shrinking waterbodies may suffer of increasing drought periods. Second, differences in developement may cause increased size-mediated intraguild predation, a common cause of reduced survival in odonate larvae. Egg development time and hatching rates were recorded of eleven egg clutches of S. vulgatum and ten clutches of S. striolatum under simulated drought vs. water and direct vs. delayed development treatments. Hatching rates were reduced under drought conditions, and particularly so in S. vulgatum. We did not observe obligate winter diapause in any of the egg clutches. But, S. vulgatum varied widely in development between clutches, while the eggs of S. striolatum developed much faster and hatched highly synchronously. This would provide S. striolatum with a temporal advantage that may lead to a size-advantage over most S. vulgatum. We also found that S. vulgatum grew faster. Faster larval growth would only compensate for those S. vulgatum with fast egg development. The current population trends may be partly attributed to lowered survival of S. vulgatum under drought and by phenological and, thus, size benefits of S. striolatum. Implications for insect conservation: Our results show that population dynamics of two closely related dragonfly species can be explained by climatically induced changes in their interactions. Understanding the causes and processes of behavioural changes resulting in differing population trends is fundamental for the protection of species. [ABSTRACT FROM AUTHOR]

The productivity of raptors is affected by different factors such as habitat, food supply, disturbance, weather conditions, and competition. Of the studied breeding parameters, success rate and breeding success significantly decreased over the years, while fledgling success and breeding density showed no trend. This study shed light on the main factors influencing the breeding success of a medium-sized raptor expanding in Europe from Asia. Modeling the factors determining the breeding success, we found that grassland availability, mean temperature during fledgling period and rainfall during nestling period influenced Long-legged buzzard reproduction (ΔAIC = 0.00, wi = 0.42, p = 0.03). The second significant model was described by weather factors excluding presence of grasslands (ΔAIC = 1.03, wi = 0.25, p = 0.05). Examining the explanatory factors, only presence of grassland in the territories demonstrated some effect on buzzard productivity. The assumption that other factors such as human disturbance, Souslik density, habitat diversity, and presence of competitors shaped buzzard's productivity did not find support in this study. This study supports the prediction of the future of Long-legged buzzard as it explored the effects of habitat and weather on its reproduction in the southern part of its distribution range. The conditions of a large-scale habitat alteration on one hand and, on the other hand, global climate change, manifested in increased rainfall during spring in Europe, draw an uncertain future for this species. Therefore, restoration of grasslands and proper habitat management, ensuring sufficient and diverse prey, is crucial for conservation of the Long-legged buzzard. [ABSTRACT FROM AUTHOR]

How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal. [ABSTRACT FROM AUTHOR]

Archaeologically defined Upper Palaeolithic (UP, 45,000–10,000 years ago) "cultures" are often used as proxies to designate fossil populations. While recent genomic studies have partly clarified the complex relationship between European UP "cultures" and past population dynamics, they leave open numerous questions regarding the biological characterization of these human groups, especially regarding the Mid-UP period (MUP, 33,000–24,000 years ago), which encompasses a pan-European cultural mosaic (Gravettian) with several regional facies. Here, we analyse a large database of well-dated and well-preserved UP crania, including MUP specimens from South-West France (SWF) and Moravia, using 3D geometric morphometrics to test for human group affinities. Our results show that the Gravettian makers from these two regions form a remarkably phenetically homogeneous sample which is different from, and more homogeneous than, the Late UP sample. Those results are congruent with genomic studies indicating a genetic continuity within the Gravettian manufacturers and a discontinuity marked by the Last Glacial Maximum (LGM). Moreover, our study expands the geographical range of the MUP phenetic continuity to SWF, for which aDNA data are scarce, and clarifies the post-LGM European population structure in SWF, with a possible dual ancestry stemming from different LGM refugia. [ABSTRACT FROM AUTHOR]

The primary cause of the long-term decline in European hares' (Lepus europaeus) population throughout Europe is widely assumed to be the intensification of agriculture. A critical component in this population dynamics is seen in the survival of leverets from birth to reproductive age. In European hares, the first stage of life until weaning has been sparsely studied, in particular habitat selection, movements and survival rate, as juveniles' precocial lifestyle is dominated by any kind of anti-predation behaviour. In the present study, free-living and pre-weaning European hares were detected systematically by thermography (n = 394), being radio-tagged or marked (n = 229) from birth until the fifth week of life to research the early juvenile survival and proximate causes of mortality. Kaplan-Meier survival curves were computed overall and in relation to the strata of season, sex and type of daytime resting place. The survival rate of radio-tagged leverets was 0.35 in the first month of life, and 0.63, 0.52 and 0.44 for the first, second and third week of life, respectively. Approximately 21.6% and 50% of all confirmed deaths occurred during the first 7 and 13 days after birth. By the end of the 4th week of life, the mortality rate caused by predation, suspected predation, agricultural practices and unexplained cases was 41.7%, 36.7%, 11.7% and 10.0%, respectively. There was no significant difference in survival between the sexes and seasons. In contrast, young hares died more frequently as a consequence of choosing a hiding place without shelter during the daytime. [ABSTRACT FROM AUTHOR]

Many developed countries have turned to immigration in order to mitigate the consequences of population aging, particularly the expected decline in the labor force population. Yet, few projection models take in consideration explicitly the differentials in labor force participation of population sub-groups. This paper describes the labor force participation module of CEPAM-Mic, which is a microsimulation model that projects several demographic, ethnocultural, and socioeconomic dimensions of the EU28 member countries population. Then, the microsimulation model is used to project EU labor force population for the period 2015–2060 under different scenarios illustrating how implementing sex- and country-specific dynamics of immigrants' integration may affect the future labor force in terms of size, rates, and gender composition. We estimated the parameters of the labor force module using logistic regressions based on the EU-Labour Force Survey (EU-LFS). In addition to age, sex, and education, immigrant-related variables are also included, such as immigrant status, place of birth, age at immigration, and duration of residence in the estimation of the probability of being active. Our results demonstrate the importance of taking into account differentials in labor force participation of population sub-groups when asserting the potential of immigration as a tool for managing population aging. In the European context, adding immigration differentials in labor force participation affects mainly downward the number of female immigrants in the labor force, while smaller differences are observed for male immigrants. An increase in immigration levels leads obviously to an increase in the total labor force size, but may also widen gender inequalities in labor force participation and has limited impact on the total labor force participation rate. Our findings suggest that relying on immigration as a tool to alleviate economic issues arising from population aging must imperatively be accompanied by strong and efficient measures to promote a full economic integration of immigrants. [ABSTRACT FROM AUTHOR]

Small mammal communities have been studied in undisturbed and restored zonal biogeocenoses in the southern subzone of eastern European tundras. The results show that the consequences of anthropogenic disturbances to the environment have an adverse effect on parameters of abundance, spatial distribution, and population dynamics of species comprising zonal communities. Soil and plant components of the disturbed biogeocenosis recover more rapidly than its small mammal community. [ABSTRACT FROM AUTHOR]

During a historically observable period, profound and often irreversible changes in the faunal composition, distribution, and abundance of game animals were taking place throughout the territory of northern Europe. These changes were especially conspicuous in case of large mammals because of their large body size and roles in biocenoses and human economic activities. This paper deals with the results of monitoring the range and abundance of the wild boar and some ecological observations on this species at the northern limit of its distribution in European Russia. [ABSTRACT FROM AUTHOR]

lthough semi-natural grasslands in Europe are declining there is often a time delay in the local extinction of grassland species due to development of remnant populations, i.e., populations with an extended persistence despite a negative growth rate. The objectives of this study were to examine the occurrence of remnant populations after abandonment of semi-natural grasslands and to examine functional traits of plants associated with the development of remnant populations. We surveyed six managed semi-natural grasslands and 20 former semi-natural grasslands where management ceased 60-100 years ago, and assessed species response to abandonment, assuming a space-for-time substitution. The response of species was related to nine traits representing life cycle, clonality, leaf traits, seed dispersal and seed mass. Of the 67 species for which data allowed analysis, 44 species declined after grassland abandonment but still occurred at the sites, probably as remnant populations. Five traits were associated with the response to abandonment. The declining but still occurring species were characterized by high plant height, a perennial life form, possession of a perennial bud bank, high clonal ability, and lack of dispersal attributes promoting long-distance dispersal. Traits allowing plants to maintain populations by utilizing only a part of their life cycle, such as clonal propagation, are most important for the capacity to develop remnant populations and delay local extinction. A considerable fraction of the species inhabiting semi-natural grasslands maintain what is most likely remnant populations after more than 60 years of spontaneous succession from managed semi-natural grasslands to forest. [ABSTRACT FROM AUTHOR]

Modelling population dynamics of the maize pest Diabrotica virgifera virgifera LeConte (western corn rootworm; Coleoptera: Chrysomelidae) requires knowledge on the growth rate (=net reproductive rate) of the species. We investigated the generational (=annual) growth rate of D. v. virgifera in isolated maize fields in southern Hungary and eastern Croatia over several years. The population densities of D. v. virgifera were assessed by absolute counts of emerging adults in 90 gauze cages per study field. Emergence ranged from 1.3 to 30.7 adults per m in continuous maize field sections, and from 0.3 to 5.1 adults per m in adjacent first-year maize sections. The annual growth rates of D. v. virgifera ranged from 0.5 to 13, and averaged in close to 4. These experimentally assessed growth rates could complement growth estimates in population dynamic models, particularly those for forecasting the population growth to economic thresholds or for estimating population build-ups after new introductions of this alien species in Europe. As an example, the determined growth rate was used to estimate that the first documented successful introduction of this species into Europe occurred between 1979 and 1984, which is 8-13 years before the detection of this species and its larval damage in maize fields near Belgrade, Serbia, in 1992. [ABSTRACT FROM AUTHOR]

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Variation of plant species cover on a Sphagnum-dominated mire in the south-eastern Alps of Italy was assessed over a 10-year period in relation to depth to the water table, peat accumulation rate, and climate. Population dynamics of vascular species appeared to be primarily affected by the autogenic process of peat accumulation, which determined the lowering of water-table position at microhabitat scale. Increase of depth to the water table through peat accumulation resulted in increased cover of ericaceous shrubs at previously moister microhabitats. Conversely, graminoid species such as Eriophorum vaginatum, Trichophorum caespitosum, and Scheuchzeria palustris, being negatively affected by autogenic peat growth, were forced to shift their niche towards the wetter end of the water-table gradient. Carex limosa and Carex rostrata decreased their cover along the whole gradient in depth to the water table, likely due to multiple processes related to peat accumulation, competition with bryophytes, and a negative feedback due to increased litter deposition. Bryophytes, in particular Sphagnum mosses, appeared more sensitive to climatic conditions, with higher precipitation favouring faster-growing species. Accordingly, Sphagnum fallax and Sphagnum magellanicum increased their cover much more than Sphagnum capillifolium, whereas Polytrichum strictum showed the strongest decrease at sites where S. magellanicum cover increased most. [ABSTRACT FROM AUTHOR]

Dairy pastoralism is integral to contemporary and past lifeways on the eastern Eurasian steppe, facilitating survival in agriculturally challenging environments. While previous research has indicated that ruminant dairy pastoralism was practiced in the region by circa 1300 BC, the origin, extent and diversity of this custom remain poorly understood. Here, we analyse ancient proteins from human dental calculus recovered from geographically diverse locations across Mongolia and spanning 5,000 years. We present the earliest evidence for dairy consumption on the eastern Eurasian steppe by circa 3000 BC and the later emergence of horse milking at circa 1200 BC, concurrent with the first evidence for horse riding. We argue that ruminant dairying contributed to the demographic success of Bronze Age Mongolian populations and that the origins of traditional horse dairy products in eastern Eurasia are closely tied to the regional emergence of mounted herding societies during the late second millennium BC.

Unambiguous evidence for the effectiveness of muskrat (Ondatra zibethicus L.) control in well-established populations in mainland Europe is lacking. Yet, this evidence is important given ongoing public challenges to the need for muskrat control and the expressed political aim of the European Union to eradicate invasive alien species, including the muskrat. In this study, indices of muskrat abundance based on livetrapping were compared among (i) sites at which muskrat control had been suspended for 3 years (suspended trapping), (ii) sites with ongoing control by kill trapping (ongoing trapping) and (iii) a site at which control efforts had ceased more than 8 years previously (no trapping). In the no trapping site, the muskrat abundance index was variable but consistently high, while in the ongoing trapping sites, the muskrat abundance index was consistently low. In the suspended trapping sites, the index of muskrat abundance increased from a level near that of the ongoing trapping sites to that of the no trapping sites. The findings are corroborated by population estimates based on data from robust design mark-recapture models and data from kill trapping. The results are interpreted as compelling proof for an effect of control on muskrat numbers, a basic premise of the control programme. [ABSTRACT FROM AUTHOR]

Cervids are keystone species in ecosystems and are associated with enormous cultural and economic value. Chronic wasting disease (CWD) is a fatal prion disease spreading in North American cervid populations. The 2016 emergence of CWD in Europe makes it urgent to understand the basics of CWD and to assess the extent to which current CWD knowledge is transferable to Europe. CWD is difficult to detect in the early stages due to very low prevalence and slow growth rates. The negative population effect of CWD is mainly due to increased female adult mortality, as infected individuals continue to reproduce. It may take decades before CWD leads to population declines. The population dynamics of mule deer are affected more by CWD than those of white-tailed deer, which in turn are more affected than those of elk, and depending on other factors limiting the populations. Species- and population-specific differences in dynamical consequences are linked to the balance among the rates of transmission, incubation period (linked to the prion protein gene, PRNP), and reproductive rates. This make it difficult to predict effects of CWD in Europe with other cervids, but the dynamic impact may be marked to cervid populations over the long term. The process of spillover across the species barrier is not well understood. Occasional spillover to moose without an apparent epizootic suggests specific conditions can limit CWD. Frequency-dependent transmission or weak density-dependent transmission makes it difficult to control CWD using density reductions through harvest and/or culling. CWD is difficult to eradicate once it becomes endemic, and it calls for immediate management actions. These actions involve extensive culling, fencing, and ceasing of wildlife feeding and are likely to cause significant controversy. [ABSTRACT FROM AUTHOR]

The roles of migration, admixture and acculturation in the European transition to farming have been debated for over 100 years. Genome-wide ancient DNA studies indicate predominantly Aegean ancestry for continental Neolithic farmers, but also variable admixture with local Mesolithic hunter-gatherers. Neolithic cultures first appear in Britain circa 4000 BC, a millennium after they appeared in adjacent areas of continental Europe. The pattern and process of this delayed British Neolithic transition remain unclear. We assembled genome-wide data from 6 Mesolithic and 67 Neolithic individuals found in Britain, dating 8500-2500 BC. Our analyses reveal persistent genetic affinities between Mesolithic British and Western European hunter-gatherers. We find overwhelming support for agriculture being introduced to Britain by incoming continental farmers, with small, geographically structured levels of hunter-gatherer ancestry. Unlike other European Neolithic populations, we detect no resurgence of hunter-gatherer ancestry at any time during the Neolithic in Britain. Genetic affinities with Iberian Neolithic individuals indicate that British Neolithic people were mostly descended from Aegean farmers who followed the Mediterranean route of dispersal. We also infer considerable variation in pigmentation levels in Europe by circa 6000 BC.

The spider crabs Inachus dorsettensis (Pennant) and Hyas coarctatus Leach are widespread in subtidal areas of muddy sand or gravel aroundwestern Europe. Both species have a life cycle with an obligatory planktonic larval phase of several weeks, which might be expected to cause widespread larval dispersal and consequent genetic homogeneity over considerable distances. However, earlier work on both taxa has indicated differences in growth pattern between populations separated bytens of kilometres. This study was undertaken to determine whether these differences were purely environmental or whether, despite the short distances involved, differences may have a genetic basis. A studyof gene frequencies, as indicated by allozymes in samples of adults collected off the Isle of Man (northern Irish Sea), indicates significant genetic differentiation between populations over a geographical distance of only about 40 km in both Inachus dorsettensis (Theta = 0.086 +/- 0.048) and Hyas coarctatus (Theta = 0.023 +/- 0.017). Variability measures differed between species, showing I. dorsettensis to have a mean number of alleles per locus of 2.5-2.6 and a range of gene diversity of 0.216-0.241, while H. coarctatus showed lower values of mean number of alleles (1.9-2.0) and a range of gene diversity from 0.122 to 0.124. Given the high expected larval mobility of the two species the results are most surprising. Possible explanations are discussed in relation to population discontinuities and patterns of larvaldrift. [ABSTRACT FROM AUTHOR]

Carabus nitens, one of the most endangered ground beetles in CentralEurope, was investigated with pitfall traps at 30 sampling sites in 17 heath fragments of the largest German heath landscape under natureconservation (nature reserve 'Luneburger Heide'). The preference fordamp Erica heaths and dry Calluna heaths in the building phase was thereby evident. Calluna heaths in the mature and degenerate phase, with and without extensive coverage by Avenella flexuosa, are either not inhabited or are avoided. The results of ovary dissections indicatethat the populations in two successive spring seasons consisted mainly of animals which had already reproduced and were therefore older than one and a half years. Allozyme electrophoreses revealed variationfor three of the nine investigated enzyme loci, and large differences in the allele frequency at one of these loci indicated genetic drift and fluctuations in the size of local populations. According to these results and statements in the literature, the loss of heathland areas and habitat quality are both responsible for the decline of the species. Suitable measures for preserving the species are (1) restoration of building phases of the Calluna heaths and (2) interconnection of at least the smaller heath fragments. Finally, recommendations aregiven for reintroductions. [ABSTRACT FROM AUTHOR]