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Animal Populations (animal + population)

Distribution by Scientific Domains

Life Sciences	77%
Medical Sciences	11%
Mathematics and Statistics	8%

Distribution within Life Sciences

Conservation Science	14%
Animal Science & Zoology	10%
Ornithology	6%

Selected Abstracts

Monte Carlo Inference for State,Space Models of Wild Animal Populations

BIOMETRICS, Issue 2 2009
Ken B. Newman
Summary We compare two Monte Carlo (MC) procedures, sequential importance sampling (SIS) and Markov chain Monte Carlo (MCMC), for making Bayesian inferences about the unknown states and parameters of state,space models for animal populations. The procedures were applied to both simulated and real pup count data for the British grey seal metapopulation, as well as to simulated data for a Chinook salmon population. The MCMC implementation was based on tailor-made proposal distributions combined with analytical integration of some of the states and parameters. SIS was implemented in a more generic fashion. For the same computing time MCMC tended to yield posterior distributions with less MC variation across different runs of the algorithm than the SIS implementation with the exception in the seal model of some states and one of the parameters that mixed quite slowly. The efficiency of the SIS sampler greatly increased by analytically integrating out unknown parameters in the observation model. We consider that a careful implementation of MCMC for cases where data are informative relative to the priors sets the gold standard, but that SIS samplers are a viable alternative that can be programmed more quickly. Our SIS implementation is particularly competitive in situations where the data are relatively uninformative; in other cases, SIS may require substantially more computer power than an efficient implementation of MCMC to achieve the same level of MC error. [source]

Therapeutic approaches to epileptogenesis,Hope on the horizon

EPILEPSIA, Issue 2010
Asla Pitkänen
Summary Prevention of epileptogenesis is an unmet need in medicine. During the last 3 years, however, several preclinical studies have demonstrated remarkable favorable effects of novel treatments on genetic and acquired epileptogenesis. These include the use of immunosuppressants and treatments that modify cellular adhesion, proliferation, and/or plasticity. In addition, the use of antiepileptic drugs in rats with genetic epilepsy or proconvulsants in acquired epilepsy models has provided somewhat unexpected favorable effects. This review summarizes these studies, and introduces some caveats when interpreting the data. In particular, the effect of genetic background, the severity of epileptogenic insult, the method and duration of seizure monitoring, and size of animal population are discussed. Furthermore, a novel scheme for defining epileptogenesis-related terms is presented. [source]

Using GIS to relate small mammal abundance and landscape structure at multiple spatial extents: the northern flying squirrel in Alberta, Canada

JOURNAL OF APPLIED ECOLOGY, Issue 3 2005
MATTHEW WHEATLEY
Summary 1It is common practice to evaluate the potential effects of management scenarios on animal populations using geographical information systems (GIS) that relate proximate landscape structure or general habitat types to indices of animal abundance. Implicit in this approach is that the animal population responds to landscape features at the spatial grain and extent represented in available digital map inventories. 2The northern flying squirrel Glaucomys sabrinus is of particular interest in North American forest management because it is known from the Pacific North-West as a habitat specialist, a keystone species of old-growth coniferous forest and an important disperser of hypogeous, mycorrhizal fungal spores. Using a GIS approach we tested whether the relative abundance of flying squirrel in northern Alberta, Canada, is related to old forest, conifer forest and relevant landscape features as quantified from management-based digital forest inventories. 3We related squirrel abundance, estimated through live trapping, to habitat type (forest composition: conifer, mixed-wood and deciduous) and landscape structure (stand height, stand age, stand heterogeneity and anthropogenic disturbance) at three spatial extents (50 m, 150 m and 300 m) around each site. 4Relative abundances of northern flying squirrel populations in northern and western Alberta were similar to those previously reported from other regions of North America. Capture rates were variable among sites, but showed no trends with respect to year or provincial natural region (foothills vs. boreal). 5Average flying squirrel abundance was similar in all habitats, with increased values within mixed-wood stands at large spatial extents (300 m) and within deciduous-dominated stands at smaller spatial extents (50 m). No relationship was found between squirrel abundance and conifer composition or stand age at any spatial extent. 6None of the landscape variables calculated from GIS forest inventories predicted squirrel abundance at the 50-m or 150-m spatial extents. However, at the 300-m spatial extent we found a negative, significant relationship between average stand height and squirrel abundance. 7Synthesis and applications. Boreal and foothill populations of northern flying squirrel in Canada appear unrelated to landscape composition at the relatively large spatial resolutions characteristic of resource inventory data commonly used for management and planning in these regions. Flying squirrel populations do not appear clearly associated with old-aged or conifer forests; rather, they appear as habitat generalists. This study suggests that northern, interior populations of northern flying squirrel are probably more related to stand-level components of forest structure, such as food, microclimate (e.g. moisture) and understorey complexity, variables not commonly available in large-scale digital map inventories. We conclude that the available digital habitat data potentially exclude relevant, spatially dependent information and could be used inappropriately for predicting the abundance of some species in management decision making. [source]

Abandonment of farmland and vegetation succession following the Eurasian plague pandemic of ad 1347,52

JOURNAL OF BIOGEOGRAPHY, Issue 4 2007
Dan Yeloff
Abstract Aim, This paper reviews the available documentary, archaeological and palaeoecological evidence for the abandonment of agricultural land and consequent regeneration of the forest in Europe after the Black Death. Location, Western and northern Europe. Methods, This review is the result of an exhaustive search of the historical, archaeological and palaeoecological literature for evidence indicating agricultural decline and forest regeneration in Eurasia during the 14th century. The available evidence for landscape change can be divided into two categories: (1) documentary and archaeological sources, and (2) palaeoecological reconstructions of past vegetation. In the past few years, several pollen diagrams from north-west Europe have been reported with precise chronologies (decadal and even annual scale) showing the abandonment of farmland and consequent ecological change in the late medieval period. Results and main conclusions, There is strong evidence of agricultural continuity at several sites in Western Europe at the time of the Black Death. The effects of the Black Death on the European rural landscape varied geographically, with major factors probably including the impact of the plague on the local population, and soil quality. At two sites in western and northern Ireland, the late medieval decline in cereal agriculture was probably a direct result of population reduction following the Black Death. In contrast, the decline in cereal production began at sites in Britain and France before the Black Death pandemic of ad 1347,52, and was probably due to the crisis in the agricultural economy, exacerbated by political instability and climate deterioration. Much of the abandoned arable land was probably exploited for grazing during the period between the decline in cereal farming and the Black Death. In the aftermath of the Black Death, grazing pressure was greatly reduced owing to reductions in the grazing animal population and a shortage of farmers. Vegetation succession on the abandoned grazing land resulted in increased cover of woody tree species, particularly Betula and Corylus, by the late 14th century. The cover of woodland was greatest at c.ad 1400, before forest clearance and agriculture increased in intensity. [source]

The Effect of Hurricane Iris on the Food Supply of Black Howlers (Alouatta pigra) in Southern Belize1

BIOTROPICA, Issue 1 2005
Mary S. M. Pavelka
ABSTRACT Hurricanes frequently affect the forests of South and Central America; however, few studies have quantified their effects to forest structure, especially when concentrating on the food supply of an animal population. Hurricane Iris made landfall in Southern Belize on 8 October 2001, severely damaging a 52 hectare site where the behavioral ecology of a population of Central American Black Howlers (Alouatta pigra) had been under study for 2.5 yr. The hurricane resulted in a mortality rate of 35 percent for major food trees, which was primarily attributed to uprooting, snapping, and major delimbing. This damage accounted for 97 percent of the food tree loss between the two sample periods. Tree species differences were found in both the percentage loss and category of damage to food trees. Trees of different heights also experienced different percentage loss and levels of damage; subcanopy and emergent trees experienced higher loss than canopy trees, and subcanopy trees were frequently uprooted. This was partially attributed to a lack of buttressing on these subcanopy trees. Buttressing was found to decrease the frequency of uprooting. Tree size was the only factor that did not influence either damage or death. Trees from which fruit were eaten by black howlers died more than twice as often as did trees eaten for leaves. [source]

Population Variability and Extinction Risk

CONSERVATION BIOLOGY, Issue 6 2000
John A. Vucetich
We resolve this conflict by attributing negative measured relationships to a statistical artifact that arises because PV tends to be underestimated for populations with short persistence. Such populations do not go extinct quickly as a consequence of low intrinsic variability; instead, the measured variability is low because they go extinct so quickly. Consequently, any underlying positive relationship between PV and ER tends to be obscured. We conducted a series of analyses to evaluate this claim. Simulations showed that negative measured relationships are to be expected, despite an underlying positive relationship. Simulations also identified properties of data, minimizing this bias and thereby permitting meaningful analysis. Experimental data on laboratory populations of a bruchid beetle (Callosobruchus maculatus) supported the simulation results. Likewise, with an appropriate statistical approach (Cox regression on untransformed data), reanalysis of a controversial data set on British island bird populations revealed a significant positive association between PV and ER (p = 0.03). Finally, a similar analysis of time series for naturally regulated animal populations revealed a positive association between PV and quasiextinction risk (p < 0.01). Without exception, our simulation results, experimental findings, reanalysis of published data, and analysis of quasiextinction risk all contradict previous reports of negative or equivocal relationships. Valid analysis of meaningful data provides strong evidence that increased population variability leads to increased extinction risk. Resumen: Los modelos poblacionales generalmente predicen un mayor riesgo de extinción (ER) al aumentar la variabilidad poblacional ( PV ,), a pesar de ello, algunas pruebas empíricas han proporcionado resultados contradictorios. Nosotros hemos resuelto este conflicto mediante la atribución de mediciones de relaciones negativas a un producto estadístico que surge debido a que la PV tiende a ser subestimada para poblaciones de persistencia corta. Estas poblaciones no se extinguen rápidamente como resultado de una variabilidad intrínseca baja; por lo contrario, la variabilidad medida es baja debido a que las poblaciones se extinguen tan rápidamente. Consecuentemente, cualquier relación positiva subyacente entre la PV y el ER tienden a ser opacadas. Llevamos a cabo una serie de análisis para evaluar este argumento. Las simulaciones mostraron que las relaciones negativas medidas son de esperarse, a pesar de una relación positiva subyacente. Las simulaciones también identificaron propiedades de los datos que minimizan este sesgo y por lo tanto permiten un análisis significativo. Los datos experimentales en poblaciones de laboratorio de un coleóptero bruchidae (Callosobruchus maculatus) respaldan los resultados de las simulaciones. De la misma manera, el uso de una técnica estadística adecuada (por ejemplo, la regresión Cox en datos sin transformar), usada en la repetición del análisis de un juego de datos controvertidos de poblaciones de aves de la Isla Británica reveló una asociación positiva significativa entre la PV y el ER (p = 0.03). Finalmente, un análisis similar de series de tiempo para poblaciones de animales reguladas de manera natural revelaron una asociación positiva entre la PV y el riesgo de cuasi-extinción (p < 0.01). Sin excepciones, nuestros resultados de simulaciones, los resultados experimentales, la repetición del análisis de datos publicados, y el análisis de riesgo de cuasi-extinción contradicen informes previos de relaciones negativas o equívocas. Los análisis válidos de datos significativos proveen una evidencia sólida de que los incrementos en la variabilidad poblacional conducen a un incremento en el riego de extinción. [source]

Sensitivity analysis of transient population dynamics

ECOLOGY LETTERS, Issue 1 2007
Hal Caswell
Abstract Short-term, transient population dynamics can differ in important ways from long-term asymptotic dynamics. Just as perturbation analysis (sensitivity and elasticity) of the asymptotic growth rate reveals the effects of the vital rates on long-term growth, the perturbation analysis of transient dynamics can reveal the determinants of short-term patterns. In this article, I present a completely new approach to transient sensitivity and elasticity analysis, using methods from matrix calculus. Unlike previous methods, this approach applies not only to linear time-invariant models but also to time-varying, subsidized, stochastic, nonlinear and spatial models. It is computationally simple, and does not require calculation of eigenvalues or eigenvectors. The method is presented along with applications to plant and animal populations. [source]

Symbolic dynamics for identifying similarity between rhythms of ecological time series

ECOLOGY LETTERS, Issue 9 2004
Bernard Cazelles
Abstract Explaining the associations between animal populations or between population and environmental signals is an important challenge. The time series that quantify animal populations are often complex, nonlinear, noisy and non-stationary. These characteristics may make it inappropriate to use traditional techniques when analysing these time series and their mutual dependencies. Here I propose to use symbolic dynamics and techniques from Information Theory to evaluate the degree of dynamic cohesion between time series fluctuations. The main idea is to check whether two (or more) signals tend to oscillate simultaneously, rising and falling together with the same rhythm. Based on synthetic and real time series, I demonstrate that this method is robust to the presence of noise and to the short length of the analysed time series and gives relevant information about the weak relationships between different series. Furthermore, this method appears as simple as classical cross-correlation and outperforms it in the analysed examples. [source]

DOES LARGE BODY SIZE IN MALES EVOLVE TO FACILITATE FORCIBLE INSEMINATION?

EVOLUTION, Issue 11 2005
A STUDY ON GARTER SNAKES
Abstract A trend for larger males to obtain a disproportionately high number of matings, as occurs in many animal populations, typically is attributed either to female choice or success in male-male rivalry; an alternative mechanism, that larger males are better able to coercively inseminate females, has received much less attention. For example, previous studies on garter snakes (Thamnophis sirtalis parietalis) at communal dens in Manitoba have shown that the mating benefit to larger body size in males is due to size-dependent advantages in male-male rivalry. However, this previous work ignored the possibility that larger males may obtain more matings because of male-female interactions. In staged trials within outdoor arenas, larger body size enhanced male mating success regardless of whether a rival male was present. The mechanism involved was coercion rather than female choice, because mating occurred most often (and soonest) in females that were least able to resist courtship-induced hypoxic stress. Males do physically displace rivals from optimal positions in the mating ball, and larger males are better able to resist such displacement. Nonetheless, larger body size enhances male mating success even in the absence of such malemale interactions. Thus, even in mating systems where males compete physically and where larger body size confers a significant advantage in male-male competition, the actual selective force for larger body size in males may relate to forcible insemination of unreceptive females. Experimental studies are needed to determine whether the same situation occurs in other organisms in which body-size advantages have been attributed to male-male rather than male-female interactions. [source]

Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range

GLOBAL CHANGE BIOLOGY, Issue 1 2010
JAMES W. PEARCE-HIGGINS
Abstract Understanding the mechanisms by which climate change will affect animal populations is vital for adaptive management. Many studies have described changes in the timing of biological events, which can produce phenological mismatch. Direct effects on prey abundance might also be important, but have rarely been studied. We examine the likely importance of variation in prey abundance in driving the demographics of a European golden plover (Pluvialis apricaria) population at its southern range margin. Previous studies have correlated plover productivity with the abundance of their adult cranefly (Tipulidae) prey, and modelled the phenology of both plover breeding and cranefly emergence in relation to temperature. Our analyses demonstrate that abundance of adult craneflies is correlated with August temperature in the previous year. Correspondingly, changes in the golden plover population are negatively correlated with August temperature 2 years earlier. Predictions of annual productivity, based on temperature-mediated reductions in prey abundance, closely match observed trends. Modelled variation in annual productivity for a future scenario of increasing August temperatures predicts a significant risk of extinction of the golden plover population over the next 100 years, depending upon the magnitude of warming. Direct effects of climate warming upon cranefly populations may therefore cause northward range contractions of golden plovers, as predicted by climate envelope modelling. Craneflies are an important food source for many northern and upland birds, and our results are likely to have wide relevance to these other species. Research into the potential for habitat management to improve the resilience of cranefly populations to high temperature should be an urgent priority. [source]

Detecting the impact of oceano-climatic changes on marine ecosystems using a multivariate index: The case of the Bay of Biscay (North Atlantic-European Ocean)

GLOBAL CHANGE BIOLOGY, Issue 1 2008
GEORGES HEMERY
Abstract Large-scale univariate climate indices (such as NAO) are thought to outperform local weather variables in the explanation of trends in animal numbers but are not always suitable to describe regional scale patterns. We advocate the use of a Multivariate Oceanic and Climatic index (MOCI), derived from ,synthetic' and independent variables from a linear combination of the total initial variables objectively obtained from Principal Component Analysis. We test the efficacy of the index using long-term data from marine animal populations. The study area is the southern half of the Bay of Biscay (43°,47°N; western Europe). Between 1974 and 2000 we monitored cetaceans and seabirds along 131000 standardized line transects from ships. Fish abundance was derived from commercial fishery landings. We used 44 initial variables describing the oceanic and atmospheric conditions and characterizing the four annual seasons in the Bay of Biscay. The first principal component of our MOCI is called the South Biscay Climate (SBC) index. The winter NAO index was correlated to this SBC index. Inter-annual fluctuations for most seabird, cetacean and fish populations were significant. Boreal species (e.g. gadiformes fish species, European storm petrel and Razorbill ,) with affinities to cold temperate waters declined significantly over time while two (Puffin and Killer Whale) totally disappeared from the area during the study period. Meridional species with affinities to hotter waters increased in population size. Those medium-term demographic trends may reveal a regime shift for this part of the Atlantic Ocean. Most of the specific observed trends were highly correlated to the SBC index and not to the NAO. Between 40% and 60% of temporal variations in species abundance were explained by the multivariate SBC index suggesting that the whole marine ecosystem is strongly affected by a limited number of physical parameters revealed by the multivariate SBC index. Aside the statistical error of the field measurements, the remaining variation unexplained by the physical characteristics of the environment correspond to the impact of anthropogenic activities such overfishing and oil-spills. [source]

The effect of habitat complexity on the functional response of a seed-eating passerine

IBIS, Issue 3 2009
DAVID J. BAKER
Recent population declines of seed-eating farmland birds have been associated with reduced overwinter survival due to reductions in food supply. An important component of predicting how food shortages will affect animal populations is to measure the functional response, i.e. the relationship between food density and feeding rate, over the range of environmental conditions experienced by foraging animals. Crop stubble fields are an important foraging habitat for many species of seed-eating farmland bird. However, some important questions remain regarding farmland bird foraging behaviour in this habitat, and in particular the effect of stubble on farmland bird functional responses is unknown. We measured the functional responses of a seed-eating passerine, the Chaffinch Fringilla coelebs, consuming seeds placed on the substrate surface in three different treatments: bare soil, low density stubble and high density stubble. Stubble presence significantly reduced feeding rates, but there was no significant difference between the two stubble treatments. Stubble reduced feeding rates by reducing the maximum attack distance, i.e. the distance over which an individual food item is targeted and consumed. The searching speed, handling time per seed, proportion of time spent vigilant, duration of vigilance bouts and duration of head-down search periods were unaffected by the presence of stubble. The frequency of vigilance bouts was higher in the bare soil treatment, but this is likely to be a consequence of the increased feeding rate. We show the influence of a key habitat type on the functional response of a seed-eating passerine, and discuss the consequences of this for farmland bird conservation. [source]

Sustaining the Ark: the challenges faced by zoos in maintaining viable populations

INTERNATIONAL ZOO YEARBOOK, Issue 1 2009
C. M. LEES
In the World Zoo and Aquarium Conservation Strategy, the world's leading zoos commit to focusing their efforts on conserving wildlife. Such a commitment is made as human activities are driving many species of wildlife towards extinction. The world's leading zoos aim to act as a counterbalance to activities that undermine the sustainability of wild populations of threatened species. However, to date, this same group of zoos has largely failed to manage its own populations of wildlife sustainably despite distinguished calls to action over the past 25 years, significant scientific input and much organizational effort. This paper explores the efforts of the global zoo community to bring sustainability and conservation value to its animal populations. It looks at where we have come from, where we are now and where we need to go from here. [source]

Effective size of populations with unequal sex ratio and variation in mating success

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 5 2002
T. Nomura
Summary To estimate the effective size (Ne) of populations with unequal sex ratio, a well-known formula, Ne=4NmNf/(Nm + Nf), has been frequently used, where Nm and Nf are the numbers of male and female parents, respectively. In this paper, the formula was examined under typical mating systems in animals. It was shown that the formula holds only when there are no variations in the numbers of mates (mating success) of parents of each sex. More appropriate equations were developed by accounting for the variation in mating success. It was found that for animal populations with harem mating system, an equation Ne=4NmNf/(2Nm+Nf) gives a more accurate estimate than the well-known formula. The effective population sizes of several wild, experimental and domestic animals are estimated by applying the derived equations to the published demographic and ecological data. Zusammenfassung Effektive Größe von Populationen mit ungleichem Geschlechterverhältnis und Variation im Anpaarungserfolg Zur Schätzung der effektiven Populationsgröße (Ne) mit ungleichem Geschlechterverhältnis, wurde häufig die allgemein bekannte Formel Ne=4NmNf/(Nm + Nf) verwendet, wobei Nm und Nf die Anzahl männlicher und weiblicher Eltern bezeichnen. In diesem Artikel wurde diese Formel unter verschiedenen Anpaarungssystemen überprüft. Es wurde gezeigt, daß die Formel nur zutrifft, wenn die Anzahl der angepaarten Tiere (Anpaarungserfolg) in jedem Geschlecht nicht variieren. Es wurden genauere Gleichungen entwickelt, die den Anpaarungserfolg mitberücksichtigen. Für Tierpopulationen mit Harempaarung wurde die Gleichung Ne=4NmNf/(2Nm + Nf) als genauerer Schätzer als die allgemein bekannte Formel gefunden. Die effektive Populationsgröße mehrerer Wild-, Versuchs- und Haustierpopulationen wurden mittels der abgeleiteten Gleichung und demographischen und ökologischen Daten geschätzt. [source]

Short-term transformation of matrix into hospitable habitat facilitates gene flow and mitigates fragmentation

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2007
NIELS BLAUM
Summary 1Habitat fragmentation has major implications for demography and genetic structure of natural plant and animal populations as small and isolated populations are more prone to extinction. Therefore, many recent studies focus on spatial fragmentation. 2However, the temporal configuration of suitable habitat may also influence dispersal and gene flow in fragmented landscapes. We hypothesize that short-term switching of inhospitable matrix areas into suitable habitat can mitigate effects of spatial fragmentation in natural and seminatural ecosystems. 3To test our hypothesis, we investigated the hairy-footed gerbil (Gerbillurus paeba, Smith 1836), a ground-dwelling rodent, in fragmented Kalahari savannah areas. Here, rare events of high above mean annual rainfall suggest short-term matrix suitability. 4During the field survey in ,matrix' areas in the Kalahari (shrub encroachment by heavy grazing) we never observed the hairy-footed gerbil in years of average rainfall, but observed mass occurrences of this species during rare events of exceptionally high rainfall. 5In a second step, we developed an agent-based model simulating subpopulations in two neighbouring habitats and the separating matrix. Our mechanistic model reproduces the mass occurrences as observed in the field and thus suggests the possibly underlying processes. In particular, the temporary improvement in matrix quality allows reproduction in the matrix, thereby causing a substantial increase in population size. 6The model demonstrates further how the environmental trigger (rainfall) impacts genetic connectivity of two separated subpopulations. We identified seasonality as a driver of fragmentation but stochasticity leading to higher connectivity. 7We found that our concept of temporal fragmentation can be applied to numerous other fragmented populations in various ecological systems and provide examples from recent literature. We conclude that temporal aspects of fragmentation must be considered in both ecological research and conservation management. [source]

Phenotypic plasticity in a maternal trait in red deer

JOURNAL OF ANIMAL ECOLOGY, Issue 2 2005
DANIEL H. NUSSEY
Summary 1Phenotypic plasticity and microevolution represent the two processes by which phenotypic traits in a population can track environmental change. While there is a growing literature documenting microevolution in reproductive traits in naturally occurring animal populations, few studies to date have examined either between-individual variation in levels of plasticity or how selection acts on plasticity. 2We present here mixed-effect linear models analysing changes in calving date in relation to autumn rainfall observed over a 30-year study of 2147 red deer on the Isle of Rum, Scotland. The study period is characterized by a phase of low and rising population density (up to and including 1980), followed by a phase of high and fluctuating population density (1981 to present). 3Variation within individual females explained a population-level trend of delayed calving dates following years of high autumn rainfall. There was significant variation between females both in their average calving dates and in their individual plastic responses of calving date to autumn rainfall. 4Females born in the low population density phase were, on average, phenotypically plastic for the calving date,autumn rainfall relationship, and showed significant variation in plasticity. Selection favoured individuals with early average calving dates among these females. 5Among females born at high population density, there was on average no significant plasticity for calving date, but variation in plastic responses was still present. Selection favoured females with increasingly positive plastic responses of calving date to autumn rainfall. 6We argue that early experience of high population density affects the physiological condition of females, making an environmental response (calving early following dry autumns) in later life physiologically untenable for all but a few high quality individuals. These same few individuals also tend to be fitter and have higher reproductive success. [source]

Host reproduction and a sexually transmitted disease: causes and consequences of Coccipolipus hippodamiae distribution on coccinellid beetles

JOURNAL OF ANIMAL ECOLOGY, Issue 1 2004
K. Mary Webberley
Summary 1We know that sexually transmitted parasites and pathogens have extremely deleterious effects in human and domesticated animal populations, but know little of sexually transmitted diseases (STDs) in natural populations. 2One previously reported natural system is the sexually transmitted mite, Coccipolipus hippodamiae, on the eastern European coccinellid, Adalia bipunctata. Our aims were to determine how widespread this parasite is in terms of incidence and prevalence across host species, to identify the causes of the prevalence pattern and whether the parasite reduces fertility in all host species. 3Coccipolipus hippodamiae was present on four of 19 European species examined. The wide distribution and high prevalence of C. hippodamiae on A. bipunctata indicates that this is the major host. The mite was also present at substantial prevalence on Adalia decempunctata and at lower prevalence on Synharmonia (=Oenopia) conglobata and Calvia quatuordecimguttata. 4Laboratory studies on mite development time and transmission efficiency revealed that although physiological factors may affect incidence, they do not explain prevalence variation between hosts, but characteristics of host life history and reproductive behaviour are important in this context. Adalia bipunctata is more promiscuous than the less commonly infected A. decempunctata and S. conglobata. Diapause is needed before breeding will occur in C. quatuordecimguttata, leading to a lack of the consistent sexual activity between generations, which is needed for STD maintenance. Calvia quatuordecimguttata is probably periodically reinfected through hybrid matings with other host species. 5Coccipolipus hippodamiae infection has similar strong deleterious effects on female reproduction in A. decempunctata and S. conglobata as have previously been demonstrated in A. bipunctata. 6The results indicate that STDs may play a profound role in the ecology of promiscuous insect populations with overlapping generations. Here they may reach significant prevalence whilst exhibiting extreme virulence. [source]

On the relation between temporal variability and persistence time in animal populations

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2003
Pablo Inchausti
Summary 1The relationship between temporal variability, spectral redness and population persistence for a large number of long-term time series was investigated. Although both intuition and theory suggest that more variability in population abundance would mean greater probability of extinction, previous empirical support for this view has not been conclusive. Possible reasons are the shortage of long-term data and the difficulties of adequately characterizing temporal variability, two issues that are explicitly addressed in this paper. 2We examined the relationship between population variability and quasi-extinction time (measured as the time required to observe a 90% decline of population abundance) for a large set of data comprising 554 populations for 123 species that were censused for more than 30 years. Two aspects of temporal variability were considered in relation with the quasi-extinction time: a baseline value (coefficient of variation over a fixed, 30-year, time scale), and a measure of the rate of increase of the population variability over time (spectral exponent). 3The results show that the quasi-extinction time was shorter for populations having higher temporal variability and redder dynamics. The relation between persistence time and population variability was compared for different taxa, trophic levels, habitat type (aquatic and terrestrial) and body sizes and compared with theoretical expectations. [source]

Density-dependent mortality is mediated by foraging activity for prey fish in whole-lake experiments

JOURNAL OF ANIMAL ECOLOGY, Issue 4 2003
Peter A. Biro
Summary 1Whereas the effects of density-dependent growth and survival on population dynamics are well-known, mechanisms that give rise to density dependence in animal populations are not well understood. We tested the hypothesis that the trade-off between growth and mortality rates is mediated by foraging activity and habitat use. Thus, if depletion of food by prey is density-dependent, and leads to greater foraging activity and risky habitat use, then visibility and encounter rates with predators must also increase. 2We tested this hypothesis by experimentally manipulating the density of young rainbow trout (Oncorhynchus mykiss) at risk of cannibalism, in a replicated single-factor experiment using eight small lakes, during an entire growing season. 3We found no evidence for density-dependent depletion of daphnid food in the nearshore refuge where most age-0 trout resided. Nonetheless, the proportion of time spent moving by individual age-0 trout, the proportion of individuals continuously active, and use of deeper habitats was greater in high density populations than in low density populations. Differences in food abundance among lakes had no effect on measures of activity or habitat use. 4Mortality of age-0 trout over the growing season was higher in high density populations, and in lakes with lower daphnid food abundance. Therefore, population-level mortality of age-0 trout is linked to greater activity and use of risky habitats by individuals at high densities. We suspect that food resources were depleted at small spatial and temporal scales not detected by our plankton sampling in the high density treatment, because food-dependent activity and habitat use by age-0 trout occurs in our lakes when food abundance is experimentally manipulated (Biro, Post & Parkinson, in press). [source]

Linking resources with demography to understand resource limitation for bears

JOURNAL OF APPLIED ECOLOGY, Issue 6 2007
MELISSA J. REYNOLDS-HOGLAND
Summary 1,Identifying the resources that limit growth of animal populations is essential for effective conservation; however, resource limitation is difficult to quantify. Recent advances in geographical information systems (GIS) and resource modelling can be combined with demographic modelling to yield insights into resource limitation. 2,Using long-term data on a population of black bears Ursus americanus, we evaluated competing hypotheses about whether availability of hard mast (acorns and nuts) or soft mast (fleshy fruits) limited bears in the southern Appalachians, USA, during 1981,2002. The effects of clearcutting on habitat quality were also evaluated. Annual survival, recruitment and population growth rate were estimated using capture,recapture data from 101 females. The availability of hard mast, soft mast and clearcuts was estimated with a GIS, as each changed through time as a result of harvest and succession, and then availabilities were incorporated as covariates for each demographic parameter. 3,The model with the additive availability of hard mast and soft mast across the landscape predicted survival and population growth rate. Availability of young clearcuts predicted recruitment, but not population growth or survival. 4,Availability of hard mast stands across the landscape and availability of soft mast across the landscape were more important than hard mast production and availability of soft mast in young clearcuts, respectively. 5,Synthesis and applications. Our results indicate that older stands, which support high levels of hard mast and moderate levels of soft mast, should be maintained to sustain population growth of bears in the southern Appalachians. Simultaneously, the acreage of intermediate aged stands (10,25 years), which support very low levels of both hard mast and soft mast, should be minimized. The approach used in this study has broad application for wildlife management and conservation. State and federal wildlife agencies often possess long-term data on both resource availability and capture,recapture for wild populations. Combined, these two data types can be used to estimate survival, recruitment, population growth, elasticities of vital rates and the effects of resource availability on demographic parameters. Hence data that are traditionally used to understand population trends can be used to evaluate how and why demography changes over time. [source]

Impacts of sudden winter habitat loss on the body condition and survival of redshank Tringa totanus

JOURNAL OF APPLIED ECOLOGY, Issue 3 2006
NIALL H. K. BURTON
Summary 1Recent theoretical modelling has provided important insights into how habitat loss may affect local populations through impacts on individual fitness (survival, body condition, fecundity). Despite this, attempts to provide empirical evidence of such impacts on displaced individuals have been limited. Using a before-after-control-impact (BACI) approach, we report how a sudden loss of wintering habitat impacted on the body condition and survival of redshank Tringa totanus. 2The intertidal mudflats of Cardiff Bay, UK, were inundated with freshwater in November 1999 following impoundment by a barrage, resulting in the displacement of c. 300 redshank to adjacent habitat on the Severn Estuary. Movements and the survival of these birds were monitored through observations of colour-marked individuals. Comparative survival rates were calculated for marked populations at the main recipient site, Rhymney, and a control site. 3Displaced redshank had difficulty maintaining their mass in the first winter post-barrage closure: adults previously only recorded at Cardiff Bay were significantly lighter than those previously recorded at Rhymney. 4Survival rates of displaced redshank also declined. The estimated annual survival of adult Cardiff Bay redshank fell from 0·846 in the 2 years pre-barrage closure to 0·778 in the 3 following years because of a significant decline in winter survival (P = 0·0006). In comparison, there was no significant change in the survival of adult Rhymney redshank, and adult survival at the control site was actually greater post-barrage closure than beforehand. The lack of decline in these rates and the similarity between those of Cardiff Bay adults pre-barrage closure and Rhymney adults indicate that the increase in winter mortality of Cardiff Bay birds resulted from their displacement. 5Synthesis and applications. This study provides the first conclusive empirical evidence that habitat loss can impact individual fitness in a bird population. Adult redshank displaced from Cardiff Bay experienced poor body condition and a 44% increase in mortality rate. Without an increase in the recruitment of first-winter birds, such a change is likely to reduce substantially local population size. The results reported here should help to inform governments, planners and non-governmental organizations (NGOs) seeking to understand how developments might impact on animal populations. [source]

Using GIS to relate small mammal abundance and landscape structure at multiple spatial extents: the northern flying squirrel in Alberta, Canada

Variable reproductive effort for two ptarmigan species in response to spring weather in a northern alpine ecosystem

JOURNAL OF AVIAN BIOLOGY, Issue 3 2010
Scott Wilson
Predicting how animal populations respond to climate change requires knowledge of how species traits influence the response of individuals to variation in anuual weather. Over a four-year study with two warm and two cold years, we examined how sympatric rock ptarmigan Lagopus muta and white-tailed ptarmigan L. leucura in the southern Yukon Territory respond to spring weather in terms of breeding phenology and the allocation of reproductive effort. The onset of breeding was approximately synchronous; for each one-degree rise in spring temperature, mean breeding dates of rock and white-tailed ptarmigan advanced by about 2.7 and 4 days respectively. Although onset of breeding was similar, the two species differed in their reproductive effort. As breeding was delayed, average first clutch sizes of rock ptarmigan declined from 9.4 to 5.8 eggs over the breeding period, while those of white-tailed ptarmigan only declined from an average of 7.8 to 6.8. Rock ptarmigan were also less likely to re-nest if their first clutch was lost to predators and as a consequence they had shorter breeding seasons. White-tailed ptarmigan produced about 25% more offspring annually than rock ptarmigan and contributed more young through re-nesting. While white-tailed ptarmigan had higher annual reproductive output, adult rock ptarmigan had a 20,25% higher annual survival rate, which may indicate a reproduction,survival trade-off for the two species. These results show that even within the same location, closely related species can differ in how they allocate effort as environmental conditions fluctuate. [source]

Using the extended quarter degree grid cell system to unify mapping and sharing of biodiversity data

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2009
R. Larsen
Abstract Information on the distribution of animal populations is essential for conservation planning and management. Unfortunately, shared coordinate-level data may have the potential to compromise sensitive species and generalized data are often shared instead to facilitate knowledge discovery and communication regarding species distributions. Sharing of generalized data is, unfortunately, often ad hoc and lacks scalable conventions that permit consistent sharing at larger scales and varying resolutions. One common convention in African applications is the Quarter Degree Grid Cells (QDGC) system. However, the current standard does not support unique references across the Equator and Prime Meridian. We present a method for extending QDGC nomenclature to support unique references at a continental scale for Africa. The extended QDGC provides an instrument for sharing generalized biodiversity data where laws, regulations or other formal considerations prevent or prohibit distribution of coordinate-level information. We recommend how the extended QDGC may be used as a standard, scalable solution for exchange of biodiversity information through development of tools for the conversion and presentation of multi-scale data at a variety of resolutions. In doing so, the extended QDGC represents an important alternative to existing approaches for generalized mapping and can help planners and researchers address conservation issues more efficiently. Résumé L'information sur la distribution des populations animales est essentielle pour la planification de la conservation et la gestion. Malheureusement, les données partagées au niveau des coordonnées risquent de compromettre les espèces sensibles, et les données généralisées sont souvent partagées pour faciliter la découverte et la communication des connaissances concernant la distribution des espèces. Le partage de données généralisées est, malheureusement, souvent opportuniste et manque de conventions mesurables qui permettraient le partage cohérent sur une plus grande échelle et à des résolutions variées. Une convention commune pour des applications africaines est le système de Quarter Degree Grid Cells (QDGC). Cependant, la norme actuelle ne supporte pas l'emploi des références uniques à travers l'Equateur et le premier méridien. Nous présentons une méthode pour étendre la nomenclature QDGC pour soutenir l'adoption de références uniques à l'échelle du continent, en Afrique. Le QDGC étendu fournit un instrument pour partager les données généralisées sur la biodiversité là où les lois, les réglementations et les autres considérations formelles empêchent ou interdisent la distribution de l'information au niveau coordonné. Nous disons dans quelle mesure le QDGC étendu peut être utilisé comme norme, une solution mesurable pour l'échange d'informations sur la biodiversité grâce au développement d'instruments pour la conversion et la présentation de données àéchelle multiple à des résolutions diverses. Ce faisant, le QDGC étendu représente une alternative importante aux approches existantes pour la cartographie généralisée et il peut aider les planificateurs et les chercheurs à traiter les problèmes de conservation plus efficacement. [source]

Possible Pleiotropic Effects of Genes Specifying Sedative/Hypnotic Sensitivity to Ethanol on Other Alcohol-Related Traits

ALCOHOLISM, Issue 10 2002
Jeremy C. Owens
Background Initial sensitivity to ethanol is a predictor of alcohol abuse that has been studied extensively in both human and animal populations. Selection for initial sensitivity to the sedative/hypnotic effects of ethanol resulted in the long-sleep and short-sleep lines of mice. Some of the genes selected in these lines could also specify differential responses in other ethanol-related phenotypes and, perhaps, for other drugs of abuse. We assessed congenic mice carrying a single quantitative trait locus (QTL) from the inbred long-sleep (ILS) or inbred short-sleep (ISS) strain on the reciprocal background for a number of ethanol- and pentobarbital-related phenotypes. Methods Each congenic strain was tested for ethanol elimination rates at 4.1 g/kg, ethanol-induced ataxia at 2.0 g/kg, ethanol-induced hypothermia at 4.1 g/kg, and pentobarbital-induced loss of righting reflex (LORR) at 60 mg/kg. Additionally, the ILS.ISS congenics were tested for low-dose ethanol-induced activation (LDA) at five doses ranging from 0.6 to 1.2 g/kg ethanol, and the ISS.ILS congenics were tested for LDA at 1.8 g/kg of ethanol. Results There was little difference in the ethanol elimination rate between congenics and background strains, although a modest sex effect was found, with the females eliminating ethanol more rapidly than the males. We were unable to replicate previous differences found in LDA for the Lore1 congenic on the ISS background, because none of the congenics differed from controls for LDA. Lore5 congenics showed a differential effect of pentobarbital-induced LORR in the expected directions. The Lore1 congenics on the ISS background showed more ethanol-induced ataxia than the ISS controls. Additionally, the hypothermic response seems affected by Lore4 and Lore5 and maybe others. Conclusions At least two regions carrying a QTL specifying sensitivity to high doses of ethanol cospecify altered sensitivity in other measures of alcohol action. Specifically, these QTLs clearly affect ethanol-induced hypothermia and pentobarbital-induced LORR and possibly ethanol-induced ataxia. [source]

Pesticides and the intoxication of wild animals

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2007
P. BERNY
Pesticides are widely used to control agricultural pests. Unfortunately, because of their biological activity, they may have detrimental effects on nontarget species. Acute toxicity, resulting in death, is reported worldwide. Although chronic and indirect effects may be even more hazardous for animal populations on a long-term basis, they are usually evaluated as parts of research programs. The purpose of this paper was to review the wildlife-poisoning surveillance systems and their results regarding the circumstances of exposure of wild animals, the pesticides involved and the species exposed. Most data are retrieved from the British and French pesticide poisoning surveillance systems in wildlife, with some data from other European structures. [source]

Sex-biased gene flow and colonization in the Formosan lesser horseshoe bat: inference from nuclear and mitochondrial markers

JOURNAL OF ZOOLOGY, Issue 3 2008
S.- F. Chen
Abstract Sex-biased behaviours are expected to play an important role in partitioning genetic variance in animal populations. Comparing genetic structure at markers with different modes of inheritance provides a means of detecting these behaviours and their consequences for population genetic structure. In colonially breeding mammals, the common combination of female philopatry and male vagility can promote contrasting patterns of genetic differentiation between the sexes, both via their effects on recurrent gene flow and on colonization. We examined sex differences in gene flow and structure by comparing maternally inherited mitochondrial DNA (mtDNA) and biparentally inherited autosomal loci in the Formosan lesser horseshoe bat Rhinolophus monoceros. We found that genetic partitioning was higher at mtDNA than autosomal markers in both sexes, indicative of female-biased philopatry and male-biased dispersal. Across Taiwan, isolation-by-distance was detected for all sex/marker combinations but was steeper for mtDNA than for nuclear markers. We suggest that isolation-by-distance shown from mtDNA at large scales is likely to reflect the stepwise founding of new breeding colonies by females during colonization. In contrast, no isolation-by-distance was found at smaller distances of up to 100 km, indicating that gene flow and/or recent shared ancestry homogenises genetic structure among nearby sites. Our results highlight the value of an indirect genetic approach to understanding sex-biased behaviours and their consequences in a little-studied species. [source]

Support for a metapopulation structure among mammals

MAMMAL REVIEW, Issue 3 2009
PIETER I. OLIVIER
ABSTRACT 1The metapopulation metaphor is increasingly used to explain the spatial dynamics of animal populations. However, metapopulation structure is difficult to identify in long-lived species that are widely distributed in stochastic environments, where they can resist extinctions. The literature on mammals may not provide supporting evidence for classic metapopulation dynamics, which call for the availability of discrete habitat patches, asynchrony in local population dynamics, evidence for extinction and colonization processes, and dispersal between local populations. 2Empirical evidence for metapopulation structure among mammals may exist when applying more lenient criteria. To meet these criteria, mammals should live in landscapes as discrete local breeding populations, and their demography should be asynchronous. 3We examined the literature for empirical evidence in support of the classical criteria set by Hanski (1999), and for the more lenient subset of criteria proposed by Elmhagen & Angerbjörn (2001). We suggest circumstances where metapopulation theory could be important in understanding population processes in mammals of different body sizes. 4The patchy distribution of large (>100 kg) mammals and dispersal often motivate inferences in support of a metapopulation structure. Published studies seldom address the full suite of classical criteria. However, studies on small mammals are more likely to record classic metapopulation criteria than those on large mammals. The slow turnover rate that is typical for medium-sized and large mammals apparently makes it difficult to identify a metapopulation structure during studies of short duration. 5To identify a metapopulation structure, studies should combine the criteria set by Hanski (1999) and Elmhagen & Angerbjörn (2001). Mammals frequently live in fragmented landscapes, and processes involved in the maintenance of a metapopulation structure should be considered in conservation planning and management. [source]

Human influences on rates of phenotypic change in wild animal populations

MOLECULAR ECOLOGY, Issue 1 2008
ANDREW P. HENDRY
Abstract Human activities can expose populations to dramatic environmental perturbations, which may then precipitate adaptive phenotypic change. We ask whether or not phenotypic changes associated with human-disturbed (anthropogenic) contexts are greater than those associated with more ,natural' contexts. Our meta-analysis is based on more than 3000 rates of phenotypic change in 68 ,systems', each representing a given species in a particular geographical area. We find that rates of phenotypic change are greater in anthropogenic contexts than in natural contexts. This difference may be influenced by phenotypic plasticity , because it was evident for studies of wild-caught individuals (which integrate both genetic and plastic effects) but not for common-garden or quantitative genetic studies (which minimize plastic effects). We also find that phenotypic changes in response to disturbance can be remarkably abrupt, perhaps again because of plasticity. In short, humans are an important agent driving phenotypic change in contemporary populations. Although these changes sometimes have a genetic basis, our analyses suggest a particularly important contribution from phenotypic plasticity. [source]

Nuclear DNA analyses in genetic studies of populations: practice, problems and prospects

MOLECULAR ECOLOGY, Issue 3 2003
De-Xing Zhang
Abstract Population-genetic studies have been remarkably productive and successful in the last decade following the invention of PCR technology and the introduction of mitochondrial and microsatellite DNA markers. While mitochondrial DNA has proven powerful for genealogical and evolutionary studies of animal populations, and microsatellite sequences are the most revealing DNA markers available so far for inferring population structure and dynamics, they both have important and unavoidable limitations. To obtain a fuller picture of the history and evolutionary potential of populations, genealogical data from nuclear loci are essential, and the inclusion of other nuclear markers, i.e. single copy nuclear polymorphic (scnp) sequences, is clearly needed. Four major uncertainties for nuclear DNA analyses of populations have been facing us, i.e. the availability of scnp markers for carrying out such analysis, technical laboratory hurdles for resolving haplotypes, difficulty in data analysis because of recombination, low divergence levels and intraspecific multifurcation evolution, and the utility of scnp markers for addressing population-genetic questions. In this review, we discuss the availability of highly polymorphic single copy DNA in the nuclear genome, describe patterns and rate of evolution of nuclear sequences, summarize past empirical and theoretical efforts to recover and analyse data from scnp markers, and examine the difficulties, challenges and opportunities faced in such studies. We show that although challenges still exist, the above-mentioned obstacles are now being removed. Recent advances in technology and increases in statistical power provide the prospect of nuclear DNA analyses becoming routine practice, allowing allele-discriminating characterization of scnp loci and microsatellite loci. This certainly will increase our ability to address more complex questions, and thereby the sophistication of genetic analyses of populations. [source]