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1.
Gonzalo lvarez Francisco C. Ceballos Tim M. Berra 《Biological journal of the Linnean Society. Linnean Society of London》2015,114(2):474-483
Charles Darwin, who was married to his first cousin Emma Wedgwood, was the first experimentalist to demonstrate the adverse effects of inbreeding. He documented the deleterious consequences of self‐fertilization on progeny in numerous plant species, and this research led him to suspect that the health problems of his 10 children, who were very often ill, might have been a consequence of his marriage to his first cousin. Because Darwin's concerns regarding the consequences of cousin marriage on his children even nowadays are considered controversial, we analyzed the potential effects of inbreeding on fertility in 30 marriages of the Darwin–Wedgwood dynasty, including the marriages of Darwin's children, which correspond to the offspring of four cousin marriages and three marriages between unrelated individuals. Analysis of the number of children per woman through zero‐inflated regression models showed a significantly adverse effect of the husband inbreeding coefficient on family size. Furthermore, a statistically significant adverse effect of the husband inbreeding coefficient on reproductive period duration was also detected. To our knowledge, this is the first time that inbreeding depression on male fertility has been detected in humans. Because Darwin's sons had fewer children in comparison to non‐inbred men of the dynasty, our findings give empirical support to Darwin's concerns on the consequences of consanguineous marriage in his own progeny. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 474–483. 相似文献
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Catherine M. Young Kristal E. Cain Nina Svedin Patricia R. Y. Backwell Sarah R. Pryke 《Ethology : formerly Zeitschrift fur Tierpsychologie》2017,123(1):41-50
In avian systems, nest predation is one of the most significant influences on reproductive success. Selection for mechanisms and behaviours to minimise predation rates should be favoured. To avoid predation, breeding birds can often deter predators through active nest defence or by modifying behaviours around the nest (e.g. reducing feeding rates and vocalisations). Birds might also benefit from concealing nests or placing them in inaccessible locations. The relative importance of these strategies (behaviour vs. site selection) can be difficult to disentangle and may differ according to life history. Tropical birds are thought to experience higher rates of predation than temperate birds and invest less energy in nest defence. We monitored a population of crimson finches (Neochmia phaeton), in the Australian tropics, over two breeding seasons. We found no relationship between adult nest defence behaviour (towards a model reptile predator) and the likelihood of nest success. However, nest success was strongly related to the visibility of the nest and the structure of the vegetation. We found no evidence that adult nest building decisions were influenced by predation risk; individuals that re‐nested after a predation event did not build their nest in a more concealed location. Therefore, predator avoidance, and hence nest success, appears to be largely due to chance rather than due to the behaviour of the birds or their choice of nesting sites. To escape high predation pressures, multiple nesting attempts both within and between seasons may be necessary to increase reproductive success. Alternatively, birds may be limited in their nest‐site options; that is, high‐quality individuals dominate quality nest sites. 相似文献
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Brood reduction, the death of one or more chicks through siblicide or starvation, can occur through density‐dependence in fecundity. Brood reduction may arise in territorial breeding systems either as a response to a high level of territorial interference in a situation of high density or as a result of habitat heterogeneity. To test the predictions of the two main hypotheses that attempt to explain how density‐dependent fecundity is generated, the Habitat Heterogeneity Hypothesis (HHH) and the Individual Adjustment Hypothesis (IAH), we analysed the relationship between density and fecundity in an expanding population of Booted Eagles in Doñana National Park, Spain, using an 18‐year data series. We also studied the occurrence and frequency of brood reduction in the same Booted Eagle population to appreciate further its effects and the factors that influence its occurrence and frequency. Our results support the HHH in the present situation of high density, as fecundity in the better territories (older and more frequently occupied) was higher than in low quality territories and was not affected by population density in high density periods. Nevertheless, the fecundity of high quality territories was affected (although not significantly) by population density in periods of low density, suggesting that the IAH was supported when only high quality territories were occupied. Older territories were used more frequently and chicks in these areas hatched earlier and suffered lower mortality than in new territories. We found a significant negative relationship between mean fecundity and its skewness, a finding that also supports HHH. During years of food shortage, less frequently occupied territories suffered higher rates of brood reduction. Brood reduction in this Booted Eagle population was a consequence of the heterogeneous structure of the habitat, with some territories having a higher probability of brood reduction than others. Parental nutritional condition did not affect brood reduction. The effect of brood reduction on nestling quality and population dynamics is also discussed. 相似文献
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Nest structures are essential for successful reproduction in most bird species. Nest construction costs time and energy, and most bird species typically build one nest per breeding attempt. Some species, however, build more than one nest, and the reason for this behaviour is often unclear. In the Grey Fantail Rhipidura albiscapa, nest abandonment before egg‐laying is very common. Fantails will build up to seven nests within a breeding season, and pairs abandon up to 71% of their nests before egg‐laying. We describe multiple nest‐building behaviour in the Grey Fantail and test four hypotheses explaining nest abandonment in this species: cryptic depredation, destruction of nests during storm events, and two anti‐predatory responses (construction of decoy nests to confuse predators, and increasing concealment to ‘hide’ nests more effectively). We found support for only one hypothesis – that abandonment is related to nest concealment. Abandoned nests were significantly less concealed than nests that received eggs. Most abandoned nests were not completely built and none received eggs, thus ruling out cryptic predation. Nests were not more likely to be abandoned following storm events. The decoy nest hypothesis was refuted as abandoned nests were constructed at any point during the breeding season and some nests were dismantled and the material used to build the subsequent nest. Thus, Grey Fantails are flexible about nest‐site locations during the nest‐building phase and readily abandon nest locations if they are found to have deficient security. 相似文献
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Oliver Robertson Martine Maron Yvonne Buckley Alan House Clive McAlpine 《Austral ecology》2014,39(3):255-266
Many passerine bird populations, particularly those that have open‐cup nests, are in decline in agricultural landscapes. Current theory suggests that an increase in habitat generalist predators in response to landscape change is partially responsible for these declines. However, empirical tests have failed to reach a consensus on how and through what mechanisms landscape change affects nest predation. We tested one hypothesis, the Additive Predation Model, with an artificial nest experiment in fragmented landscapes in southern Queensland, Australia. We employed structural equation modelling of the influence of the relative density of woodland and habitat generalist predators and landscape features at the nest, site, patch and landscape scales on the probability of nest predation. We found little support for the Additive Predation Model, with no significant influence of the density of woodland predators on the probability of nest predation, although landscape features at different spatial scales were important. Within woodlands fragmented by agriculture in eastern Australia, the presence of noisy miner colonies appears to influence ecological processes important for nest predation such that the Additive Predation Model does not hold. In the absence of colonies of the aggressive native bird, the noisy miner, the influence of woodland predators on the risk of artificial nest predation was low compared with that of habitat generalist predators. Outside noisy miner colonies, we found significant edge effects with greater predation rates for artificial nests within woodland patches located closer to the agricultural matrix. Furthermore, the density of habitat generalist predators increased with the extent of irrigated land‐use, suggesting that in the absence of noisy miner colonies, nest predation increases with land‐use intensity at the landscape scale. 相似文献
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The population declines of waders in Europe are widely considered to have resulted from habitat loss and degradation due to agricultural changes. However, recent empirical evidence suggests that levels of predation on wader nests are unsustainably high in many cases, even in some situations where breeding habitat is otherwise favourable. We review the published and 'grey' literature on nest predation on waders in Europe and quantify the relative importance of the major predators. Nest cameras offer the least biased method of identifying and quantifying nest predators. A small number of camera studies, in combination with others utilizing nest temperature loggers, indicate that nocturnal/mammalian predators make the largest contribution to wader nest predation. More than half of site-years or studies reviewed reported clutch failure rates of over 50% attributable to predation alone, a rate that is likely to be associated with declining populations, although parameters such as chick and adult survival will also affect population trends. Correlates of wader nest predation are documented, with time of season, field type and management, distance to habitat/field edge, wader nest density, and abundance of mammalian predators being most consistently identified. Future directions of research into wader productivity are discussed, and we suggest that studies quantify additional life-history parameters such as chick survival, as well as examining the predator community, wherever possible. 相似文献
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Joseph Mwangi Henry K. Ndithia Rosemarie Kentie Muchane Muchai B. Irene Tieleman 《Journal of avian biology》2018,49(8)
Nest survival is critical to breeding in birds and plays an important role in life‐history evolution and population dynamics. Studies evaluating the proximate factors involved in explaining nest survival and the resulting temporal patterns are biased in favor of temperate regions. Yet, such studies are especially pertinent to the tropics, where nest predation rates are typically high and environmental conditions often allow for year‐round breeding. To tease apart the effects of calendar month and year, population‐level breeding activity and environmental conditions, we studied nest survival over a 64‐month period in equatorial, year‐round breeding red‐capped larks Calandrella cinerea in Kenya. We show that daily nest survival rates varied with time, but not in a predictable seasonal fashion among months or consistently among years. We found negative influences of flying invertebrate biomass and rain on nest survival and higher survival of nests when nests were more abundant, which suggests that nest predation resulted from incidental predation. Although an increase in nest predation is often attributed to an increase in nest predators, we suggest that in our study, it may be caused by altered predator activity resulting from increased activity of the primary prey, invertebrates, rather than activity of the red‐capped larks. Our results emphasize the need to conduct more studies in Afro‐tropical regions because proximate mechanisms explaining nest predation can be different in the unpredictable and highly variable environments of the tropics compared with the relatively predictable seasonal changes found in temperate regions. Such studies will aid in better understanding of the environmental influences on life‐history variation and population dynamics in birds. 相似文献
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Trias Wahyuni Rakhmawati Geert Molenberghs Geert Verbeke Christel Faes 《Biometrical journal. Biometrische Zeitschrift》2016,58(6):1390-1408
We consider models for hierarchical count data, subject to overdispersion and/or excess zeros. Molenberghs et al. ( 2007 ) and Molenberghs et al. ( 2010 ) extend the Poisson‐normal generalized linear‐mixed model by including gamma random effects to accommodate overdispersion. Excess zeros are handled using either a zero‐inflation or a hurdle component. These models were studied by Kassahun et al. ( 2014 ). While flexible, they are quite elaborate in parametric specification and therefore model assessment is imperative. We derive local influence measures to detect and examine influential subjects, that is subjects who have undue influence on either the fit of the model as a whole, or on specific important sub‐vectors of the parameter vector. The latter include the fixed effects for the Poisson and for the excess‐zeros components, the variance components for the normal random effects, and the parameters describing gamma random effects, included to accommodate overdispersion. Interpretable influence components are derived. The method is applied to data from a longitudinal clinical trial involving patients with epileptic seizures. Even though the data were extensively analyzed in earlier work, the insight gained from the proposed diagnostics, statistically and clinically, is considerable. Possibly, a small but important subgroup of patients has been identified. 相似文献
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John R. Morrongiello Chris T. Walsh Charles A. Gray Jerom R. Stocks David A. Crook 《Global Change Biology》2014,20(6):1844-1860
How individuals respond to environmental change determines the strength and direction of biological processes like recruitment and growth that underpin population productivity. Ascertaining the relative importance of environmental factors can, however, be difficult given the numerous mechanisms through which they affect individuals. This is especially true in dynamic and complex estuarine environments. Here, we develop long‐term otolith‐based indices of recruitment and growth for estuary perch Percalates colonorum (Bemm River, Australia), to explore the importance of intrinsic (individual, demographic) and extrinsic (hydrologic, climatic, density‐dependent) factors in driving estuarine fish productivity. Analyses involved a novel zero‐inflated specification of catch curve regression and mixed effects modelling. The 39 years of recruitment and 46 years of growth data, spanning a period of environmental change including severe drought, displayed considerable inter‐annual variation. Recruitment success was strongly related to high freshwater inflows during the spawning season, suggesting that these conditions act as spawning cues for adults and potentially provide favourable conditions for larvae. Individuals displayed age‐dependent growth, with highest rates observed at younger ages in years characterized by warm temperatures, and to a lesser degree, greater magnitude base inflow conditions. We detected systematic among‐year‐class growth differences, but these were not attributable to year class strength, suggesting that environmental conditions experienced by individuals as juveniles can have long‐lasting effects of greater importance to population productivity than density‐dependent growth responses. The primacy of temperature in driving growth variation highlights that under‐appreciated climatic variation can affect estuarine fish productivity through direct physiological and indirect food web mechanisms. We predict that climatic warming will promote individual growth in southerly populations of P. colonorum but concurrently limit recruitment due to forecast reductions in spawning season river discharge. Disparate trait responses are likely in other fishes as they respond to multiple and changing environmental drivers, making predictions of future population productivity challenging. 相似文献
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Erin L. Hewett Ragheb Karl E. Miller Erin Hoerl Leone 《Journal of Field Ornithology》2019,90(4):309-324
Increasing nest survival by excluding predators is a goal of many bird conservation programs. However, new exclosure projects should be carefully evaluated to assess the potential risks of disturbance. We tested the effectiveness of predator exclosure fences (hereafter, fences) for nests of critically endangered Florida Grasshopper Sparrows (Ammodramus savannarum floridanus) at a dry prairie site (Three Lakes; 2015–2018) and a pasture site (the Ranch; 2015–2016) in Osceola County, Florida, USA. We installed fences at nests an average of 8 days after the start of incubation, and nest abandonment after fence installation was rare (2 of 149 installations). Predation was the leading cause of failure for unfenced nests at both sites (48–73%). At Three Lakes, nest cameras revealed that mammals and snakes were responsible for 61.5% and 38.5% of predation events, respectively, at unfenced nests. Fences reduced the daily probability of predation (0.016 for fenced nests vs. 0.074 for unfenced nests). The probability that a fenced nest would survive from discovery to fledging was more than double that of unfenced nests (60.4% vs. 27.7%). However, we found no difference in daily nest survival at the Ranch between the year before nests were fenced (2015; 0.874) and the year when all but one nest were fenced (2016; 0.867) because red imported fire ants (Solenopsis invicta) were responsible for 86% of predation events at fenced nests at the Ranch. The use of cameras at fenced nests revealed that site‐specific differences in nest predators explained variation in fence efficiency between sites. Our fence design may be useful for other species of grassland birds, but site‐specific predator communities and species‐specific response of target bird species to fences should be assessed before installing fences at other sites. 相似文献
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The nest of the Yellow-rumped Thornbill Acanthiza chrysorrhoa (endemic to Australia) consists of a lower domed nest where the young are cared for and an upper cup-shaped structure, referred to as the false nest. Numerous hypotheses have been proposed to explain the primary function of the false nest, but their predictions remain largely untested. Here, we test predictions of the nest mimicry hypothesis (with artificial nests) whereby the empty false nest acts as a decoy, deflecting visual nest predators and/or brood parasites away from the true nest below, thereby increasing nesting success. Clear detection of the false nest by adversaries is an intrinsic aspect of nest mimicry; thus we also test whether conspicuous nests (natural) are favoured by natural selection. Specifically, (1) we compare predation level at artificial domed nests with and without a false nest; and (2) we analyse associations between nest site concealment and nesting outcome in natural nests in a wild population. Supporting the nest mimicry hypothesis, predation level was significantly lower for artificial domed nests with false nests, and for natural nests with lower levels of concealment. 相似文献
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KAREL WEIDINGER 《Ibis》2009,151(2):352-360
I used time-lapse videotaping to identify predators of open songbird nests in fragmented deciduous woodland (nine plots, 2–10 ha each) in the Czech Republic from 2002 to 2006. I documented 22 species of predators at 171 nests of 13 species (mainly Blackcap Sylvia atricapilla , Song Thrush Turdus philomelos , Common Blackbird Turdus merula , Yellowhammer Emberiza citrinella and Chaffinch Fringilla coelebs ). The main predators were Pine Marten Martes martes (37% of 178 predation events), Jay Garrulus glandarius (29%), Buzzard Buteo buteo (7%) and Great Spotted Woodpecker Dendrocopos major (7%); mammals accounted for 48% of total predation. At least 3% of nests were depredated by multiple predators. In spite of their local abundance, Hooded Crows Corvus cornix did not present a serious threat for shrub nesting songbirds (< 1% of total predation). No predation by mice was recorded, suggesting that their importance has been overestimated in artificial nest studies. The proportional species composition of predators depended on which species occupied the monitored nest and location (study plot), but not on the year or the time of season. Corvids and raptors accounted for a relatively larger percentage of total predation of small ('warblers') and large ('thrushes') prey species, respectively, whereas carnivores were important predators of all prey species. Active nests of thrushes were only rarely robbed by Jays (< 4% of 52 events), presumably due to parental nest defence. Predation by woodpeckers was spatially clumped, probably due to individual foraging specialization. Predation by the other major predators was documented on most/all study plots. 相似文献
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Understanding causes of nest loss is critical for the management of endangered bird populations. Available methods for estimating nest loss probabilities to competing sources do not allow for random effects and covariation among sources, and there are few data simulation methods or goodness‐of‐fit (GOF) tests for such models. We developed a Bayesian multinomial extension of the widely used logistic exposure (LE) nest survival model which can incorporate multiple random effects and fixed‐effect covariates for each nest loss category. We investigated the performance of this model and the accompanying GOF test by analysing simulated nest fate datasets with and without age‐biased discovery probability, and by comparing the estimates with those of traditional fixed‐effects estimators. We then exemplify the use of the multinomial LE model and GOF test by analysing Piping Plover Charadrius melodus nest fate data (n = 443) to explore the effects of wire cages (exclosures) constructed around nests, which are used to protect nests from predation but can lead to increased nest abandonment rates. Mean parameter estimates of the random‐effects multinomial LE model were all within 1 sd of the true values used to simulate the datasets. Age‐biased discovery probability did not result in biased parameter estimates. Traditional fixed‐effects models provided estimates with a high bias of up to 43% with a mean of 71% smaller standard deviations. The GOF test identified models that were a poor fit to the simulated data. For the Piping Plover dataset, the fixed‐effects model was less well‐supported than the random‐effects model and underestimated the risk of exclosure use by 16%. The random‐effects model estimated a range of 1–6% probability of abandonment for nests not protected by exclosures across sites and 5–41% probability of abandonment for nests with exclosures, suggesting that the magnitude of exclosure‐related abandonment is site‐specific. Our results demonstrate that unmodelled heterogeneity can result in biased estimates potentially leading to incorrect management recommendations. The Bayesian multinomial LE model offers a flexible method of incorporating random effects into an analysis of nest failure and is robust to age‐biased nest discovery probability. This model can be generalized to other staggered‐entry, time‐to‐hazard situations. 相似文献
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- Multiyear drought is projected to increase in frequency and duration in arid and semiarid regions across the world, threatening native species and ecosystem function. The effects of multiyear drought are often exacerbated by human water use for consumption, energy production, and agriculture, which, in lentic ecosystems, manifest in reduced lake elevation and altered habitat for aquatic species.
- Here, we demonstrate that decreasing lake levels, associated with drought and water management, reduce the availability of littoral cobble habitat to fishes by creating an elevation‐explicit littoral habitat map. We combined long‐term fish catch data and a lake elevation time series with our elevation‐explicit littoral habitat map to test whether fish species population demographics are related to drought‐driven changes in littoral habitat.
- We surveyed the littoral zone of Bear Lake, Utah and Idaho, U.S.A., from full pool to a depth of >12 m, totalling 94.86 km2 surveyed. As lake elevation decreased >6 m from full pool to the lowest historical elevation, the area of littoral cobble decreased by >97%. Bear Lake sculpin (Cottus extensus, Cottidae), a cold‐water fish species which relies on cobble for reproduction, catch per unit effort decreased by >75% with littoral cobble, and year class strength declined by as much as 86%, but varied across age.
- We predicted the response of age‐0 to age‐4 sculpin under high and low cobble availability. Our simulations predict a 60%–85% decline in juvenile sculpin CPUE (age‐2 and younger) when cobble availability decreases from the 95th to 5th percentile.
- Our study provided a unique opportunity to identify quantitative linkages between climate‐driven littoral habitat loss and an ecologically important profundal fish species, expanding our understanding of potential future pathways through which climate change may affect lentic ecosystems and fishes.
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Ana Gracanin Erin Roger Andrew C. Katsis Luke S. O&#x;Loughlin Nathan J. Emery Joanne F. Ocock James C. O&#x;Hanlon 《Austral ecology》2020,45(5):523-528
Maintaining suitable vegetation within urban environments is crucial for wildlife conservation in the face of anthropogenic habitat change. Here, we report on a citizen science project, involving students from seven schools across south‐eastern Australia, that investigated the effectiveness of urban vegetation as habitat for bird nests. The ‘nest concealment hypothesis’ posits that vegetation should obscure the nest from predator detection, thus reducing the likelihood of predation. To test this, participating school‐aged citizen scientists constructed artificial nests, which were placed in garden trees within school grounds and monitored for signs of predation. We found no evidence to support the nest concealment hypothesis, with no relationship between the density of vegetation immediately surrounding a nest and its likelihood of predation (binomial model: = 1.714, P = 0.190). It was observed that 80% of the nests experienced predation. This aligns with mounting evidence suggesting that other factors, such as olfaction and adult defence, may be more important factors in the protection of bird nests. It is important to note that artificial nests are unreliable, and therefore, the veracity of the overall conclusions is limited. However, in conducting this experiment, we demonstrate the suitability of this method as a school‐based citizen science activity. This study exemplifies that field‐based experiments can used to engage future generations with conservation science. 相似文献
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巢捕食是驱动鸟类行为进化的一个重要因素,促使鸟类进化出一系列的行为策略。为探究鸟类应对不同巢捕食者的行为策略,于2016年4-7月利用赤峰锦蛇(Elaphe anomala)和花鼠(Tamias sibiricus)模拟巢入侵实验,基于人工巢箱分别在育雏前期(子代6-8日龄)和育雏后期(子代15-17日龄)对杂色山雀(Sittiparus varius)亲鸟和雏鸟的反捕食行为进行了研究。结果显示:杂色山雀亲鸟的巢防御行为和雏鸟的反捕食行为会根据繁殖进程和捕食者类型的变化而进行调整。亲鸟应对捕食者行为的强度随繁殖进程的推进而升高(OR=3.061, P=0.003),随捕食者的危险程度的增加而降低(OR=0.451,P=0.023)。亲鸟报警鸣声的激烈程度随捕食者危险程度的增加而增加,随繁殖进程的推进而升高(P < 0.001)。雏鸟在育雏前期对亲鸟的报警鸣声均无任何回应;但在育雏后期听到亲鸟对花鼠的报警鸣声时,均迅速停止一切活动并静默蹲踞在巢箱底部(n=31,P < 0.001),当听到亲鸟对赤峰锦蛇的报警鸣声时,87.1%繁殖巢的雏鸟均会迅速尝试逃出巢箱,其余繁殖巢雏鸟则仍是静默蹲踞在巢底(n=31,P < 0.001)。 相似文献