Trends In Population Dynamics Research Articles

КОМПЛЕКСНА ОЦІНКА ДИНАМІКИ ЧИСЕЛЬНОСТІ УГРУПОВАНЬ КОЛОНІАЛЬНИХ НАВКОЛОВОДНИХ ПТАХІВ (НА ПРИКЛАДІ ДЕЯКИХ ОСТРОВІВ СИВАШУ)

<p>The problem of the mathematical analysis of the number dynamics of the nesting waterbirds for the islands of the south of Ukraine is examined. The algorithm of the evaluation of changes in the number of island birds is proposed. Data of the long-term monitoring of the number of birds were analyzed according to this algorithm. The necessity of the implementation of the statistical indices together with the graphic representation of island birds’ turnover is proved. The trends of population dynamics are determined for the key species. The discussed procedure of the complex evaluation is proposed for the management planning of the island bird species and their habitats.</p> <p>The performed analysis of the number dynamics of the key-stone breeding island birds showed that, with the exception of little tern, the population status and the prognosis of number are sufficiently favorable. From the data of long-term monitoring we came up with the conclusion about the existence of island habitats with carrying capacity to maintain the additional number of breeding birds. In the case of unfavorable conditions like strengthening of anthropogenic press, concurrent interrelations, deficiency of feed resources or drastic reduction of breeding biotopes, the birds due to turnover are capable to successfully react even without reducing their number and breeding success. The extinction rate of the breeding bird species from the island sites directly correlates with the number of breeding species. For the species with equal abundance, the extinction probability is higher for birds, whose numbers are unstable and characterized by significant fluctuations. This testifies the urgency of the constant monitoring and analysis of the number dynamics of breeding bird species in region.</p> <p>The suggested procedure of analysis is recommended for drawing up of management plans and performing of prognoses of number of breeding island bird species. More detail analysis with use of quantitative data on breeding birds will be the next step of the study of the island birds’ turnover. The results of the analysis of population dynamics assist to count the minimal population size for the colonization of new islands and stable existence of bird communities. Detailed analysis will allow to estimate the effect of competition on population and to determine the competitive variability inside and between the species breeding on islands.</p> <p><em>Key words: Ukraine, colonial waterbirds, islands, dynamics of number, analysis</em></p> <p> </p>

Erratum

Marine EcologyVolume 32, Issue 4 p. 538-538 Free Access Erratum This article corrects the following: Trends in population dynamics and fishery of Parapenaeus longirostris and Nephrops norvegicus in the Tyrrhenian Sea (NW Mediterranean): the relative importance of fishery and environmental variables Alessandro Ligas, Paolo Sartor, Francesco Colloca, Volume 32Issue s1Marine Ecology pages: 25-35 First Published online: April 4, 2011 First published: 03 May 2011 https://doi.org/10.1111/j.1439-0485.2011.00455.xAboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat In Ligas et al. (2011) the left-hand running head was incorrectly included as: Trends in P. congirostris and N. norvegicus The correct text should have been: Trends in P. longirostris and N. norvegicus We apologise for this error. Reference Ligas A., Sartor P., Colloca F. (2011) Trends in population dynamics and fishery of Parapenaeus longirostris and Nephrops norvegicus in the Tyrrhenian Sea (NW Mediterranean): the relative importance of fishery and environmental variables. Marine Ecology, 32(Suppl. 1), 25– 35. Wiley Online LibraryWeb of Science®Google Scholar Volume32, Issue4December 2011Pages 538-538 ReferencesRelatedInformation

Trends in population dynamics and fishery of Parapenaeus longirostris and Nephrops norvegicus in the Tyrrhenian Sea (NW Mediterranean): the relative importance of fishery and environmental variables

AbstractTemporal variation in the population abundance of the deep‐water rose shrimp, Parapenaeus longirostris (Lucas, 1846) (Decapoda, Penaeidae), and the Norway lobster, Nephrops norvegicus (Linnaeus, 1758) (Decapoda, Nephropidae), in the Tyrrhenian Sea (NW Mediterranean), were evaluated using time‐series data (1994–2008) from experimental trawl surveys and commercial landings. The influence of several environmental variables (sea surface temperature, wind‐mixing index and NAO index) and fishing effort indices (number of days at sea per month and mean engine power of the trawl fleet) were investigated. The time series were analysed by means of min/max auto‐correlation factor analysis (MAFA) and dynamic factor analysis (DFA). The abundance of P. longirostris showed a clear increasing trend, significantly correlated with the fishing effort index (number of days at sea per month), the sea surface temperature and the wind‐mixing index. The temporal variations in the stock of P. longirostris, which has a preference for warm waters, were positively correlated with the rise of the sea surface temperature and the decrease of wind circulation. For N. norvegicus, an increasing trend of landings per unit of effort and recruitment index contrasted with a decreasing trend of relative population abundance (biomass and density indices).

Waterfowl, macrophytes, and the clear water state of shallow lakes

The importance of lake ecosystems for waterfowl remains a topic of debate. In order to assess how temporal variations in lake features, specifically shifts between alternative stable states, may interact with the waterfowl fauna, we performed a long-term (22 years) study of the shallow Lake Krankesjon, southern Sweden. Lower total numbers of waterfowl occurred during periods with low macrophyte cover and turbid water, than when submersed macrophytes flourished and the water was clear. Some specific functional groups of waterfowl, such as herbivores, invertebrate, and fish feeders, showed a positive relation to clear water and high macrophyte cover. Hence, our data suggest that some migratory waterfowl may select lakes based on water quality, thereby adjusting their large-scale migratory routes. On the other hand, omnivorous waterfowl exhibited their highest abundances during turbid conditions. Furthermore, waterfowl not primarily relying on food from the lake showed no response to fluctuations in turbidity or macrophyte cover, but followed regional trends in population dynamics. In our study lake, L. Krankesjon, we estimated that waterfowl remove less than 3% of the macrophyte biomass during a stable clear-water state with lush macrophyte beds. However, during transition periods between alternative stable states, when macrophyte biomass is lower and the plants already stressed, the consumption rate of waterfowl may have a stronger effect on lake ecosystem functioning.

Landscape fragmentation influences winter body mass of roe deer

Body size of large herbivores is a crucial life history variable influencing individual fitness‐related traits. While the importance of this parameter in determining temporal trends in population dynamics is well established, much less information is available on spatial variation in body size at a local infra‐population scale. The relatively recent increase in landscape fragmentation over the last century has lead to substantial spatial heterogeneity in habitat quality across much of the modern agricultural landscape. In this paper, we analyse variation in body mass and size of roe deer inhabiting a heterogeneous agricultural landscape characterised by a variable degree of woodland fragmentation. We predicted that body mass should vary in relation to the degree of access to cultivated meadows and crops providing high quality diet supplements. In support of our prediction, roe deer body mass increased along a gradient of habitat fragmentation, with the heaviest deer occurring in the most open sectors and the lightest in the strict forest environment. These spatial differences were particularly pronounced for juveniles, reaching >3 kg (ca 20% of total body mass) between the two extremes of this gradient, and likely have a marked impact on individual fates. We also found that levels of both nitrogen and phosphorous were higher in deer faecal samples in the more open sectors compared to the forest environment, suggesting that the spatial patterns in body mass could be linked to the availability of high quality feeding habitat provided by the cultivated agricultural plain. Finally, we found that adults in the forest sector were ca 1 kg lighter for a given body size than their counterparts in the more open sectors, suggesting that access to nutrient rich foods allowed deer to accumulate substantial fat reserves, which is unusual for roe deer, with likely knock‐on effects for demographic traits and, hence, population dynamics.

Demographic variation between populations of Caladenia orientalis - a fire-managed threatened orchid

Caladenia orientalis (G.W.Carr) Hopper & A.P.Br. is a critically endangered orchid. The largest known populations are confined to fire-managed coastal heathland in southern Victoria. Trends in population dynamics at two closely occurring sites were evaluated against time since fire and rainfall, between 2000 and 2008, to provide ecological and biological information relevant to population management. At both sites, decreased plant size was inversely correlated with time since fire and the number of non-reproductive plants was positively correlated with time since fire. Rates of flowering were inversely correlated with time since fire at only one site (Population 2). The vegetation at this site rapidly accumulated after fire, whereas recovery was relatively slow at the other site. Rainfall was not correlated with rates of flowering or leaf width at either of the study sites, although there was a weak inverse relationship between rainfall and the number of non-reproductive plants at one site (Population 1). Rates of pollen transport and fruit set were within reported ranges for deceptive species. Fruiting plants were significantly smaller in the following year, whereas non-reproductive plants remained the same size. The results suggest that there may be costs associated with reproductive effort, and that hand-pollinating plants to boost seed production may lead to decreased plant size in the following year. Annual variation in rates of flowering may be influenced by previous reproductive effort. However, long-term population trends are better explained by competition from dominant shrubs, which become increasingly abundant with a lack of fire. Future management prescriptions should include site-specific fire regimes to maintain an open heathland.

Scaling up population dynamic processes in a ladybird–aphid system

AbstractHere, we study how scaling up to the metapopulation level affects predictions of a population dynamics model motivated by an aphidophagous predator–aphid system. The model incorporates optimization of egg distribution in predatory females, cannibalism among their offspring, and self‐regulation of the prey population. These factors determine the within‐year dynamics of the system and translate the numbers of prey and predator individuals at the beginning of the season into their numbers at the end of the season at the level of one patch—one suitable host plant or a group of these. At the end of each season, all populations of prey and all populations of predators are mixed (this simulates aphid host‐alternation and ladybird migration to hibernation sites), and then redistributed at the beginning of the next season. Prey individuals are distributed at random among the patches as a “prey rain”, while adult predators that survived from the previous season optimize the distribution of their offspring, in that they prefer patches with sufficient amount of prey and absence of other predators. This redistribution followed by within‐season dynamics is then iterated over many seasons. We look at whether small‐scale trends in population dynamics predicted by this model are consistent with large‐scale outcomes. Specifically, we show that even on the metapopulation scale, the impact of predators on prey metapopulation is relatively low. We further show how the dates of predator arrival to and departure from the system affect the qualitative behaviour of the model predictions.

Cyclical behaviour of the tide-pool ciliate Strombidium oculatum

This study developed a field-based system to examine the influence of cyclical distur- bances on populations and metapopulations. We have examined the population dynamics of a tide- pool ciliate that possesses several cycles, endogenously and exogenously induced, ranging in scale from hours to years. Strombidium oculatum Gruber exhibits an endogenous circatidal behaviour: for ~6 h, at low tide, S. oculatum is free-swimming in pools, and ~20 to 60 min before flushing of the pools it encysts on a substrate. Encystment lasts for ~19 h: 2 high tides and 1 intervening low tide. Excyst- ment then occurs the next day ~30 to 40 min after the pools are isolated. This behaviour allows S. ocu- latum to remain in pools and creates isolated populations; a matrix of such pools on the shore then comprises a metapopulation. Over a 5 yr period, we conducted a study to examine (1) the timing of division and the cell cycle; (2) the endogenous, 25 h encystment-excystment cycle; (3) the tidally induced fortnightly behaviour; (4) the seasonally induced long-term variation in population abun- dance; and (5) the seasonal change in distribution on the shore. We found that ciliates on the Isle of Man exhibit an excystment-encystment pattern similar to that previously described for populations of S. oculatum in France: cells divide almost immediately after excysting, allowing the ciliate population to rapidly exploit potential food resources; 2 populations exist in each pool, each isolated to a single low tide; the ciliate exhibits seasonal trends in population dynamics, appearing in the spring and dis- appearing in the autumn; and ciliates appear to survive seasonal changes by remaining at low den- sities in upper-shore pools during the winter. We have used these data and other measurements of the population dynamics to discern how populations are maintained on the shore, and we discuss these mechanisms in the context of population-metapopulation survival.

HABITAT COMPLEXITY, SPATIAL INTERFERENCE, AND “MINIMUM RISK DISTRIBUTION”: A FRAMEWORK FOR POPULATION STABILITY

In the past century, the debate over whether or not density-dependent factors regulate populations has generally focused on changes in mean population density, ignoring the spatial variance around the mean as unimportant noise. In an attempt to provide a different framework for understanding population dynamics based on individual fitness, this paper discusses the crucial role of spatial variability itself on the stability of insect populations. The advantages of this method are the following: (1) it is founded on evolutionary principles rather than post hoc assumptions; (2) it erects hypotheses that can be tested; and (3) it links disparate ecological schools, including spatial dynamics, behavioral ecology, preference-performance, and plant apparency into an overall framework. At the core of this framework, habitat complexity governs insect spatial variance. which in turn determines population stability. First, the minimum risk distribution (MRD) is defined as the spatial distribution of individuals that results in the minimum number of premature deaths in a population given the distribution of mortality risk in the habitat (and, therefore, leading to maximized population growth). The greater the divergence of actual spatial patterns of individuals from the MRD, the greater the reduction of population growth and size from high, unstable levels. Then, based on extensive data from 29 populations of the processionary caterpillar, Ochrogaster lunifer, four steps are used to test the effect of habitat interference on population growth rates. (1) The costs (increasing the risk of scramble competition) and benefits (decreasing the risk of inverse density-dependent predation) of egg and larval aggregation are quantified. (2) These costs and benefits, along with the distribution of resources, are used to construct the MRD for each habitat. (3) The MRD is used as a benchmark against which the actual spatial pattern of individuals is compared. The degree of divergence of the actual spatial pattern from the MRD is quantified for each of the 29 habitats. (4) Finally, indices of habitat complexity are used to provide highly accurate predictions of spatial divergence from the MRD, showing that habitat interference reduces population growth rates from high, unstable levels. The reason for the divergence appears to be that high levels of background vegetation (vegetation other than host plants) interfere with female host-searching behavior. This leads to a spatial distribution of egg batches with high mortality risk, and therefore lower population growth. Knowledge of the MRD in other species should be a highly effective means of predicting trends in population dynamics. Species with high divergence between their actual spatial distribution and their MRD may display relatively stable dynamics at low population levels. In contrast, species with low divergence should experience high levels of intragenerational population growth leading to frequent habitat-wide outbreaks and unstable dynamics in the long term. Six hypotheses, erected under the framework of spatial interference, are discussed, and future tests are suggested.

Microbial population shifts in experimental rice systems

Biogeochemically relevant constituents of rice soil microbial communities exhibit profound population shifts during a rice cropping cycle on irrigated fields. Greenhouse experiments were designed to examine the effects of the less stable environmental conditions in submergence- and drought-prone rainfed rice cropping systems on soil microbiota. Successions of cultivable groups of microorganisms (guilds) with assumed key functions in nutrient cycling were assessed under different water regimes. Frequently, microbial population dynamics for both planted and unplanted trials converged both in the flooded field and under controlled submergence in the greenhouse. An induced mid season drought as is typical for rainfed rice cropping systems proved not long enough to reverse prevailing trends in population dynamics of most of the functional groups investigated. Irrespective of the water regime, total bacterial cell counts declined toward the end of the cropping period. In contrast, a fast build-up of heterotrophic biomass by copiotrophic bacteria peaked at the flowering stage. This trend was most pronounced under drought conditions, but also significant under submergence. It leveled off towards harvest and the subsequent fallow period. Fungi as primary microbial digesters of crop residues showed a negative correlation with the soil water content and were predominant only under drought or post-harvest fallow conditions. N-remobilizing, proteolytic bacteria declined strongly in the flooded field, whereas drought reversed this trend in the greenhouse. Observations of successive increases of anaerobic guilds in the field were confirmed under permanent flooding in the greenhouse. Peaks of denitrifiers, mainly triggered by post-season puddling, appeared and disappeared early in the plant growth cycle. Ammonium oxidizing nitrifiers showed extremely low titers under submergence, but also in planted trials under drought. This suggested a negative rhizosphere effect under water limitation. For other guilds, differences between planted and unplanted trials were less pronounced.

Trends in population dynamics and exploitation of North Sea plaice (Pleuronectes platessaL.) since the late 1800s

The exploitation history of North Sea plaice is reconstructed from the late 1800s to 1993 using data on catch per unit of effort, total international landings, size and age composition of landings, and growth rate. Available data indicate that fishing mortality was already high in the 1890s (Fu=0.4) and increased to a record high in the late 1920s and early 1930s (F=0.8). After World War II, fishing mortality was reduced, but from the 1960s onwards it increased steadily to a level of F=0.6 in the early 1990s. Indices of catch per unit of effort during the last quarter of the 19th century are concurrent with the expansion of the fisheries. Stock biomass was at a low level in the 1930s but increased between the 1960s and 1980s owing to increased recruitment and improved growth. Landings were fairly stable around 55 000 t until the mid-1950s when they increased almost threefold to a record level of 170 000 t in 1989. The causes of these changes are discussed. It is suggested that changes in both growth rate and exploitation rate in young fish have been important.

The demographic development of the USSR over seventy years.

Past trends in population dynamics in the Soviet Union are reviewed, with particular attention paid to the demographic impact of World War II.

Aging in sub-Saharan Africa: Toward a redefinition of needs research and policy directions

This paper reviews the trends in population dynamics for the elderly in Sub-Saharan Africa, the changing role of the elderly in family and kinship systems, the place of the elderly in development efforts by national governments, and new directions for research and policy on aging. The paper concludes with suggestions for improving the quality of care given to the elderly. Attention is directed to issues of health, nutrition, housing, social welfare, employment, income and social security, and education and training for the elderly in the region. Emphasis is placed on fostering cooperation between the countries in the area.

The survival of traditional medicine in a Peruvian Barriada

Current trends in population dynamics reflect increasing movement from rural to urban environments. As a result the provision of health care for migrants has become a national priority in many countries ‘in development’. Information describing the extent to which traditional medical beliefs and practices persist is crucial to the formation of systems of health care for migrant communities. This paper describes the dynamics of medical conservatism. Data analysis obtained from a comparative study of 52 Peruvian women living in a rural highland province and 50 Peruvian women from a migrant squatter settlement, a barriada, indicates that length of exposure to an urban environment is less of a determinant in medical conservatism than age of enculturation. Positive and negative implications of medical conservatism for the delivery of health services are discussed. Recommendations are suggested for greater emphasis on the coordination of programs of health care with community education.

Monitoring the Health Status of Pest Populations as a Contribution towards the Establishment of Economic Thresholds

ABSTRACTKnowledge of pest population dynamics is required to assess the future abundance of a pest, the losses to be expected and the economic threshold. Mortality of pests caused by diseases can greatly influence their development and a valuable assessment can therefore only be based on healthy individuals. Examples of monitoring the health status are usually taken from the forest and from such insects that develop slowly and allow an assessment of the epizootic before the damaging final instar has been reached (caterpillars, sawflies). In agriculture, the tendency of reducing crop rotation increases the permanence of regulative forces and is consequently favourable. This allows for a more precise prediction on the development of epizootics. Recent observations show that appropriate sampling of aphid populations designed to determine their health status in respect to fungal epizootics can greatly increase the accuracy of the forecast on future trends in population dynamics.

Population Dynamics in Bangladesh: Data sources, current facts and past trends

An understanding of past, from which we learn, and present, through which we observe, population dynamics is necessary for development planning for a country. This paper studies this present facts of and past trends in population dynamics paying particular attention to the major demographic variables of population, fertility, mortality, and migration profiles in the last two decades with an assessment of various demographic data sources in Bangladesh. In doing so various literatures were reviewed and secondary data were generated mostly from international sources, like database of the United Nations, Population Reference Bureau, US Census Bureau etc., and partly from national sources, like population census, Bangladesh demographic and health survey etc., which are the major sources of demographic data for Bangladesh. The study observes that the demographic indicators of Bangladesh have shown considerable development during the last two decades. Though the population increased in size but growth showed a declining trend. The total fertility rate declined from 3.96 children per woman during 1990- 1995 to 2.36 during 2005-2010, and infant mortality and under-five mortality rates almost halved during the same period. Life expectancy at birth recently reached to 69 years from 56 years in 1990. Moreover, international outmigration showed an increasing trend with a very low rate for female. Keywords: Demographic data; Population; Fertility; Mortality; Migration DOI: http://dx.doi.org/10.3329/jbau.v9i1.8754 JBAU 2011; 9(1): 121-130

キャベツ株内でのモンシロチョウ,ヨトウガおよびタマナギンウワバの幼虫と蛹の葉位別分布

In the vicinity of the North Eastern end of Honshu, three crops of cabbages are produced each year: early summer, late summer and fall crops. To investigate the seasonal trends in population dynamics of the caterpillars in cabbage fields, egg, larvae and pupae of Pieris rapae crucivora BOISD., Plusia nigrisigna WALKER and Mamestra brassicae L. on cabbage plants were counted in fields of respective crops, during May to September, 1959.The seasonal changes in the average number of eggs, each instar larvae and pupae of the three species per plant in respective fields are given in Figs. 1, 2 and 3. Among these species, Mamestra brassicae was the most abundant during June to early July, and Pieris rapae crucivora during the late July, August and September. Plusia nigrisigna did not attain a significant proportion of the total population at all. As to the total number of the insects observed throughout the overall season, Pieris rapae crucivora was the most numerous, Mamestra brassicae came next, and Plusia nigrisigna showed no significant proportion. The caterpillar population reached its highest level in early September. In general, 50 per cent or more of the initial population in each generation of respective species was destroyed during the egg and the first larval instar. Moreover, 80 per cent or more of the survivors failed to pupate. The rate of reduction in number of early summer population of Pieris rapae crucivora was particularly high when the population density of Mamestra brassicae was the highest.

キャベツ畑における主要りんし目害虫の個体群動態の比較研究

In the vicinity of the North Eastern end of Honshu, three crops of cabbages are produced each year: early summer, late summer and fall crops. To investigate the seasonal trends in population dynamics of the caterpillars in cabbage fields, egg, larvae and pupae of Pieris rapae crucivora BOISD., Plusia nigrisigna WALKER and Mamestra brassicae L. on cabbage plants were counted in fields of respective crops, during May to September, 1959.The seasonal changes in the average number of eggs, each instar larvae and pupae of the three species per plant in respective fields are given in Figs. 1, 2 and 3. Among these species, Mamestra brassicae was the most abundant during June to early July, and Pieris rapae crucivora during the late July, August and September. Plusia nigrisigna did not attain a significant proportion of the total population at all. As to the total number of the insects observed throughout the overall season, Pieris rapae crucivora was the most numerous, Mamestra brassicae came next, and Plusia nigrisigna showed no significant proportion. The caterpillar population reached its highest level in early September. In general, 50 per cent or more of the initial population in each generation of respective species was destroyed during the egg and the first larval instar. Moreover, 80 per cent or more of the survivors failed to pupate. The rate of reduction in number of early summer population of Pieris rapae crucivora was particularly high when the population density of Mamestra brassicae was the highest.