Evolutionary and Plastic Phenotypic Change Can Be Just as Fast as Changes in Population Densities.

Studying the change in population distribution and density can provide important basis for regional development and planning. The spatial patterns and driving factors of the change in population density in China were not clear yet. Therefore, using the population census data in 2000 and 2010, this study firstly analyzed the change of population density in China and divided the change in all 2353 counties into 4 types, consisting of rapid increase, slow increase, slow decrease and rapid decrease. Subsequently, based on the partial least square (PLS) regression method, we recognized the significant factors (among 11 natural and social-economic factors) impacting population density change for the whole country and counties with different types of population change. The results showed that: (1) compared to the population density in 2000, in 2010, the population density in most of the counties (over 60%) increased by 21 persons per km2 on average, while the population density in other counties decreased by 13 persons per km2. Of all the 2353 counties, 860 and 589 counties respectively showed rapid and slow increase in population density, while 458 and 446 counties showed slow and rapid decrease in population density, respectively. (2) Among the 11 factors, social-economic factors impacted population density change more significantly than natural factors. The higher economic development level, better medical condition and stronger communication capability were the main pull factors of population increase. The dense population density was the main push factor of population decrease. These conclusions clarified the spatial pattern of population change and its influencing factors in China over the past 10 years and could provide helpful reference for the future population planning.

One of the most immediate responses to disturbance is a change in population density. Change in plant population density may have an effect on visiting and pollinating insects which may influence both fecundity and gene flow. The management regime of the grasslands has a major influence on the density and distribution of plant species. Changes in the management in the river valley grasslands of the Drentse Aa from intensive grassland production to mowing once a year without the applications of fertilizers has caused large changes in the density and distribution of Rhinanthus angustifolius. Initially the density rose than fall becoming very abundant locally (de Hullu et al., 1985). This study considers the effect of population density on visitation pollination and gene exchange.

C. J. Krebs, 2013. Population Fluctuations in Rodents. University of Chicago Press, Chicago, Illinois, ix + 306 pp. ISBN 978-0-226-01035-9, price (hardbound), $55.00. Charles Krebs has been a leader in the study of the population dynamics of small mammals for decades, and this book presents both his analyses of specific hypotheses and syntheses of general patterns. The book summarizes a vast literature and will serve as an admirable introduction to population dynamics for its target audience, advanced undergraduates and graduate students and ecologists outside the field. Krebs makes clear that he is concerned with population fluctuations in general, not just population cycles, but most of the book is devoted to results for arvicoline rodents (lemmings and voles), a group that provides several classic examples of population cycling. Krebs has strong ideas regarding the proper approach to population ecology. As he sees it, there are 2 problems regarding changes in population densities, 1 spatial and 1 temporal. The spatial problem involves shifts in average density of rodents across different habitats, differences that he believes usually reflect different availability of resources, particularly food and cover (protection from predation). The temporal problem, which consumes most of the book, concerns changes in density through time within a habitat, which is the traditional realm of population dynamics. He argues that one should attack the latter problem by finding environmental factors that strongly influence rates of population change and not density per se, a stance that may underemphasize the interaction of environmental factors with density. Krebs provides background in the first 2 chapters by considering different ways to classify population change, including time-series analysis, and geographical shifts in patterns of population dynamics, particularly those that change with latitude. …

Phenological trends provide important indicators of environmental change and population dynamics. However, the use of untested population-level measures can lead to incorrect conclusions about phenological trends, particularly when changes in population structure or density are ignored. We used individual-based estimates of birth date and lactation duration of harbour seals (Phoca vitulina) to investigate energetic consequences of changes in pupping phenology. Using generalized linear mixed models, we first demonstrate annual variation in pupping phenology. Second, we show a negative relationship between lactation duration and the timing of pupping, indicating that females who pup early nurse their pups longer, thereby highlighting lactation duration as a useful proxy of female condition and resource availability. Third, individual-based data were used to derive a population-level proxy that demonstrated an advance in pupping date over the last 25 years, co-incident with a reduction in population abundance that resulted from fisheries-related shootings. These findings demonstrate that phenological studies examining the impacts of climate change on mammal populations must carefully control for changes in population density and highlight how joint investigations of phenological and demographic change provide insights into the drivers of population declines.

Changes in the density and distribution of Ixodes dammini, Spielman Clifford, Piesman & Corwin were assessed in Wisconsin by examining hunter-killed deer for ticks in 1981 and 1989. Deer examination sites were distributed widely across the state and included 23 sites in 1981 and 15 sites in 1989; 10 sites were visited both years. Between 1981 and 1989, I. dammini became more abundant throughout its range, and I. dammini range expanded into the southwestern portion of Wisconsin. I. dammini was not found in the eastern one-third of the state. When compared with 1981, the 1989 survey revealed significant increases in the proportion of infested deer in the southwest (Arena), higher levels of infestation of individual deer (number of ticks per individual deer) in the central west (Bangor-W. Salem), and significantly less disparity between the proportions of infested male deer and infested female deer in the north (Spooner) compared with sites farther south. These results are consistent with a pattern of I. dammini range expansion from north to south, followed by an increase in population density in the colonized areas. Dermacentor albipictus Packard was present throughout the range of I. dammini and at sites in the northeastern quadrant of Wisconsin where I. dammini was not found. The range of D. albipictus did not change between the survey years, but its population density increased significantly at sites in the north. There is no evidence for interaction between the two tick species that might affect tick distribution or population density, nor can the greater number of I. dammini found in 1989 be attributed to increased tick activity because of warmer weather; temperatures were cooler in 1989 than 1981.

In this paper we contrast the spatial patterns of population density and other demographic changes in growing versus shrinking MSAs from 1980 to 2010. We find that, on average, shrinking MSAs show the steepest drop in population density near the Central Business District (CBD). Motivated by this fact, we explore the connection between changes in population density at the core of the MSA and MSA productivity. We find that changes in near-CBD population density are positively associated with per capita income growth at the MSA-level.

Market dynamics of community pharmacies in Minnesota

Computer models can be helpful tools to provide a better understanding of the mechanisms responsible for the complex movements of cyanobacteria resulting from changes in buoyancy and mixing of the water column in a lake. Kromkamp & Walsby (1990) developed a vertical migration model for Oscillatoria, that was based on the experimentally determined relationship between the rates of density change and photon irradiance in this cyanobacterium. To adapt this model to Microcystis, we determined related changes in carbohydrate content in cultures of Microcystis. Samples were incubated at various constant values of photon irradiance and then placed in the dark. The changes in carbohydrate content of the cells during these incubations were investigated. The relationship between the ratio of carbohydrate to protein and cell density in Microcystis was established to permit conversion of the rates of carbohydrate change to rates of density change. By plotting the calculated rates of density change against the values of photon irradiance experienced during the incubations, an irradiance-response curve of density change was established. The curve showed a distinct maximum at 278 mol photons m 2 s 1 . At higher values of photon irradiance, the rate of density change was strongly inhibited. A positive linear correlation was found between cell density and the rates of density decrease in the dark. The validity of the use of rate equations of density change, which are based on short-term incubations at constant values of photon irradiance, to predict density changes in Microcystis in fluctuating light regimes was tested. This was accomplished by measuring the time course of change in carbohydrate content of two continuous cultures of Microcystis, which were submitted to fluctuating light regimes, and comparing the results with the changes in the carbohydrate contents of these cultures predicted by the rate equations of carbohydrate change. The results showed good agreement: the rate equations of density change were therefore introduced into the model to simulate vertical migration of Microcystis .T he model predicts that the maximum migration depth of Microcystis will increase with colony size up to a maximum of 200 m radius. The effect of colony size on the net increase in cell density during the light period was also investigated with the model. It predicts that small colonies have a higher net increase in cell density than large colonies, but are inhibited at high photon irradiances at the surface.

AimThe recent recovery of large carnivores in Europe has been explained as resulting from a decrease in human persecution driven by widespread rural land abandonment, paralleled by forest cover increase and the consequent increase in availability of shelter and prey. We investigated whether land cover and human population density changes are related to the relative probability of occurrence of three European large carnivores: the grey wolf (Canis lupus), the Eurasian lynx (Lynx lynx) and the brown bear (Ursus arctos).LocationEurope, west of 64° longitude.MethodsWe fitted multi‐temporal species distribution models using >50,000 occurrence points with time series of land cover, landscape configuration, protected areas, hunting regulations and human population density covering a 24‐year period (1992–2015). Within the temporal window considered, we then predicted changes in habitat suitability for large carnivores throughout Europe.ResultsBetween 1992 and 2015, the habitat suitability for the three species increased in Eastern Europe, the Balkans, North‐West Iberian Peninsula and Northern Scandinavia, but showed mixed trends in Western and Southern Europe. These trends were primarily associated with increases in forest cover and decreases in human population density, and, additionally, with decreases in the cover of mosaics of cropland and natural vegetation.Main conclusionsRecent land cover and human population changes appear to have altered the habitat suitability pattern for large carnivores in Europe, whereas protection level did not play a role. While projected changes largely match the observed recovery of large carnivore populations, we found mismatches with the recent expansion of wolves in Central and Southern Europe, where factors not included in our models may have played a dominant role. This suggests that large carnivores’ co‐existence with humans in European landscapes is not limited by habitat availability, but other factors such as favourable human tolerance and policy.

Behaviour is the interface between an organism and its environment, and behavioural plasticity is important for organisms to cope with environmental change. Social behaviour is particularly important because sociality is a dynamic process, where environmental variation influences group dynamics and social plasticity can mediate resource acquisition. Heterogeneity in the ecological environment can therefore influence the social environment. The combination of the ecological and social environments may be interpreted collectively as the "socioecological environment," which could explain variation in fitness. Our objective was to outline a framework through which individual social and spatial phenotypes can be integrated and interpreted as phenotypes that covary as a function of changes in the socioecological environment. We propose the socioecological environment is composed of individual behavioural traits, including sociality and habitat selection, both of which are repeatable, potentially heritable and may reflect animal personality traits. We also highlight how ecological and social niche theory can be applied to the socioecological environment framework, where individuals occupy different socioecological niches. Individual sociality and habitat selection are also density-dependent, and theory predicts that density-dependent traits should affect reproduction, survival, and therefore fitness and population dynamics. We then illustrate the proximate links between sociality, habitat selection and fitness as well as the ultimate, and possibly adaptive, consequences associated with changes in population density. The ecological, evolutionary and applied implications of our proposed socioecological environment framework are broad and changes in density could influence individual fitness and population dynamics. For instance, human-induced environmental changes can influence population density, which can affect the distribution of social and spatial phenotypes within a population. In summary, we outline a conceptual framework that incorporates individual social and spatial behavioural traits with fitness and we highlight a range of ecological and evolutionary processes that are likely associated with the socioecological environment.

The changing size distribution of cities in China affects productivity, food security, resource use, and macroeconomic fragility. The legacy of central planning, and especially the mobility restrictions from hukou registration, hampered evolution of the city size distribution, creating a need for rapid adjustment in city sizes in the more market-oriented era. We use China’s three latest censuses of population (for 2000, 2010 and 2020) to show how the city size distribution is changing, for 265 cities containing 98% of China’s urban residents. We also form remote sensing estimates of urbanized area for the same cities and same period. Rank-size regressions show that the population distribution of cities is becoming less equal over time, while urbanized area is becoming more equal. The population growth of many big cities is not being aided by fast enough urban area expansion in those places, but urban area elsewhere expands faster than required by slow growth in their number of residents. The elasticity of changes in population density with respect to changes in city population exceeds 0.5 for cities in China’s eastern region but is significantly lower in the central region and lower still in the western region, where growth in city population is almost entirely accommodated by growth in city area, with little change in density. We relate these diverging trends to China’s macroeconomic fragility coming from the real estate sector and to regional differences in urban agglomeration effects that may generate productive spillovers.

Echinoderms play a key role in structuring many marine ecosystems and are notorious for large population density variations in so‐called “outbreak” or “dieoff” events. In a review of this phenomenon, we assess the causal factors and ecological and evolutionary consequences. We identified 28 species (6 Asteroidea, 8 Echinoidea, 10 Holothuroidea, 4 Ophiuroidea) that exhibit large (more than two population doublings or halvings) population density changes. Three generalized patterns were identified and named for exemplary species: (1) rapid decreases followed by no or slow recovery (Diadema–Paracentrotus Model), (2), rapid increase and apparent stability at a new population density (Amperima–Amphiura Model), and (3) population density fluctuations (Acanthaster–Asterias Model). Echinoderms identified were distributed from the shallow intertidal to the deep sea, and from tropical to temperate regions. In most cases, significant impacts on the respective ecosystems were observed. The most striking similarity among all species identified was possession of the ancestral‐type planktotrophic larva. This larval type was significantly overrepresented in species identified within the Asteroidea, Echinoidea, Holothuroidea, and for the combined data set. We suggest three main factors that render a life history with planktotrophic larvae a high‐risk–high‐gain strategy: (1) a strong nonlinear dependency of larval production on adult densities (Allee effects), (2) a low potential for compensatory feedback mechanisms, and (3) an uncoupling of larval and adult ecology. The alternative (derived) lecithotrophic larva occurs in 68% of recent echinoderm species, suggesting an evolutionary trend toward this larval type. Lecithotrophic development represents a more buffered life history because compensatory feedback between adult densities and larval output is likely to be more efficient. For lecithotrophic developers, direct nutritive coupling from adult to larva to the early benthic juvenile provides a buffer against starvation. Lecithotrophic larvae are independent of the vagaries of planktonic food supply, and their short planktonic duration may promote local recruitment. Anthropogenic influences contributed to the population density variations in most cases, including increased primary productivity through eutrophication or global change, disease, overfishing, and species introductions. We suggest that anthropogenic disturbance, through its influence on the frequency and/or amplitude of echinoderm population density changes, may go beyond present ecosystem impacts and alter future evolutionary trends.

Time variation in exospheric sodium density on Mercury

Response of blood coagulation parameters to elevated endogenous 17β-estradiol levels induced by human menopausal gonadotropins

Understanding the driving forces behind built-up land expansion is crucial in urban planning and management. Using the Pearl River Delta urban agglomeration as research area, four landscape metrics were used to analyze landscape characteristics of urban expansion from 1990 to 2015. Spatial autocorrelation analysis was used to study the characteristics of built-up land expansion, while geographical detector was employed to identify the driving forces of urban land growth and their interactions. The results show the extent of built-up land has been increasing, the structure has become more complex, the level of fragmentation has been increasing, and the aggregation degree is in decline. The built-up landscape index shows spatial heterogeneity occurring in the core and peripheral towns of cities, as well as in the core and peripheral areas of the entire region. Also, changes in the built-up landscape index indicate increased spatial aggregation occurring in the past 25 years. Results from the geographical detector show natural, socio-economic, and transportation-related factors have substantial influence on built-up land expansion. Elevation, slope, population density, change in population density, and road network density were shown to have high influencing power. The influencing powers of slope and change in population density were also found to be different from other factors, highlighting their important role in urban development. Also, there were two types of interactions found, enhance nonlinear and enhance bivariate interactions, indicating the compounding influence of interactions between significant determinants. This study provides a new perspective and methodological approach in evaluating the driving forces behind built-up land expansion and their interactions.