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1.
J Anim Ecol ; 2024 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-38650117

RESUMO

Research Highlight: Rademaker, M., van Leeuwen, A., & Smallegange, I. M. (2024). Why we cannot always expect life history strategies to directly inform on sensitivity to environmental change. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.14050. Ecological studies have long delved into how organisms allocate energy between reproduction and somatic maintenance to maximize fitness. This allocation gives rise to various life-history strategies, and these strategies have been shown to predict how populations respond to environmental change, allowing us to generalize potential responses to increasing human pressures. Such predictions have, however, been made for a limited set of terrestrial taxa and typically do not explore how individual differences in life-history responses to environmental change scale to affect population-level responses. Using novel data on diverse fish species, Rademaker et al. (2024) construct models that link individual-level trade-offs in energy allocation under environmental change to population-level life-history strategies. A key finding in their study is that short-lived species are not more sensitive to environmental change-unlike results of previous studies. This study represents a new generation of work that underscores the complexity of predicting population responses to environmental shifts and suggests a need for a broader understanding of individual-level mechanisms. The results of Rademaker et al. (2024) encourage further mechanistic life-history analyses across a wider range of species and populations to validate the exciting findings and explore their implications across diverse ecological contexts.

2.
Glob Chang Biol ; 29(23): 6693-6712, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37819148

RESUMO

Megaherbivores play "outsized" roles in ecosystem functioning but are vulnerable to human impacts such as overhunting, land-use changes, and climate extremes. However, such impacts-and combinations of these impacts-on population dynamics are rarely examined using empirical data. To guide effective conservation actions under increasing global-change pressures, we developed a socially structured individual-based model (IBM) using long-term demographic data from female giraffes (Giraffa camelopardalis) in a human-influenced landscape in northern Tanzania, the Tarangire Ecosystem. This unfenced system includes savanna habitats with a wide gradient of anthropogenic pressures, from national parks, a wildlife ranch and community conservation areas, to unprotected village lands. We then simulated and projected over 50 years how realistic environmental and land-use management changes might affect this metapopulation of female giraffes. Scenarios included: (1) anthropogenic land-use changes including roads and agricultural/urban expansion; (2) reduction or improvement in wildlife law enforcement measures; (3) changes in populations of natural predators and migratory alternative prey; and (4) increases in rainfall as predicted for East Africa. The factor causing the greatest risk of rapid declines in female giraffe abundance in our simulations was a reduction in law enforcement leading to more poaching. Other threats decreased abundances of giraffes, but improving law enforcement in both of the study area's protected areas mitigated these impacts: a 0.01 increase in giraffe survival probability from improved law enforcement mitigated a 25% rise in heavy rainfall events by increasing abundance 19%, and mitigated the expansion of towns and blockage of dispersal movements by increasing abundance 22%. Our IBM enabled us to further quantify fine-scale abundance changes among female giraffe social communities, revealing potential source-sink interactions within the metapopulation. This flexible methodology can be adapted to test additional ecological questions in this landscape, or to model populations of giraffes or other species in different ecosystems.


Assuntos
Girafas , Animais , Humanos , Feminino , Ecossistema , Mudança Climática , Tanzânia
3.
Proc Natl Acad Sci U S A ; 120(14): e2214244120, 2023 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-36972440

RESUMO

Seasonal tropical environments are among those regions that are the most affected by shifts in temperature and rainfall regimes under climate change, with potentially severe consequences for wildlife population persistence. This persistence is ultimately determined by complex demographic responses to multiple climatic drivers, yet these complexities have been little explored in tropical mammals. We use long-term, individual-based demographic data (1994 to 2020) from a short-lived primate in western Madagascar, the gray mouse lemur (Microcebus murinus), to investigate the demographic drivers of population persistence under observed shifts in seasonal temperature and rainfall. While rainfall during the wet season has been declining over the years, dry season temperatures have been increasing, with these trends projected to continue. These environmental changes resulted in lower survival and higher recruitment rates over time for gray mouse lemurs. Although the contrasting changes have prevented the study population from collapsing, the resulting increase in life-history speed has destabilized an otherwise stable population. Population projections under more recent rainfall and temperature levels predict an increase in population fluctuations and a corresponding increase in the extinction risk over the next five decades. Our analyses show that a relatively short-lived mammal with high reproductive output, representing a life history that is expected to closely track changes in its environment, can nonetheless be threatened by climate change.


Assuntos
Cheirogaleidae , Mudança Climática , Animais , Humanos , Dinâmica Populacional , Animais Selvagens , Temperatura , Mamíferos , Estações do Ano , Cheirogaleidae/fisiologia
4.
Proc Biol Sci ; 290(1993): 20221494, 2023 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-36809806

RESUMO

In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting-but are rarely available. Here, we first review the current shortcomings in assessing demographic feedbacks in population and community dynamics. We then present an overview of advances in statistical tools that provide an opportunity to leverage population-level data on abundances of multiple species to infer stage-specific demography. Lastly, we showcase a state-of-the-art Bayesian method to infer and project stage-specific survival and reproduction for several interacting species in a Mediterranean shrub community. This case study shows that climate change threatens populations most strongly by changing the interaction effects of conspecific and heterospecific neighbours on both juvenile and adult survival. Thus, the repurposing of multi-species abundance data for mechanistic forecasting can substantially improve our understanding of emerging threats on biodiversity.


Assuntos
Biodiversidade , Mudança Climática , Dinâmica Populacional , Teorema de Bayes , Previsões , Ecossistema
5.
Ecology ; 104(3): e3894, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36208282

RESUMO

The fate of natural populations is mediated by complex interactions among vital rates, which can vary within and among years. Although the effects of random, among-year variation in vital rates have been studied extensively, relatively little is known about how periodic, nonrandom variation in vital rates affects populations. This knowledge gap is potentially alarming as global environmental change is projected to alter common periodic variations, such as seasonality. We investigated the effects of changes in vital-rate periodicity on populations of three species representing different forms of adaptation to periodic environments: the yellow-bellied marmot (Marmota flaviventer), adapted to strong seasonality in snowfall; the meerkat (Suricata suricatta), adapted to inter-annual stochasticity as well as seasonal patterns in rainfall; and the dewy pine (Drosophyllum lusitanicum), adapted to fire regimes and periodic post-fire habitat succession. To assess how changes in periodicity affect population growth, we parameterized periodic matrix population models and projected population dynamics under different scenarios of perturbations in the strength of vital-rate periodicity. We assessed the effects of such perturbations on various metrics describing population dynamics, including the stochastic growth rate, log λS . Overall, perturbing the strength of periodicity had strong effects on population dynamics in all three study species. For the marmots, log λS decreased with increased seasonal differences in adult survival. For the meerkats, density dependence buffered the effects of perturbations of periodicity on log λS . Finally, dewy pines were negatively affected by changes in natural post-fire succession under stochastic or periodic fire regimes with fires occurring every 30 years, but were buffered by density dependence from such changes under presumed more frequent fires or large-scale disturbances. We show that changes in the strength of vital-rate periodicity can have diverse but strong effects on population dynamics across different life histories. Populations buffered from inter-annual vital-rate variation can be affected substantially by changes in environmentally driven vital-rate periodic patterns; however, the effects of such changes can be masked in analyses focusing on inter-annual variation. As most ecosystems are affected by periodic variations in the environment such as seasonality, assessing their contributions to population viability for future global-change research is crucial.


Assuntos
Ecossistema , Incêndios , Periodicidade , Dinâmica Populacional , Crescimento Demográfico
6.
Proc Biol Sci ; 289(1979): 20221117, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35892214

RESUMO

Life-history strategies are diverse. While understanding this diversity is a fundamental aim of evolutionary biology and biodemography, life-history data for some traits-in particular, age-dependent reproductive investment-are biased towards females. While other authors have highlighted this sex skew, the general scale of this bias has not been quantified and its impact on our understanding of evolutionary ecology has not been discussed. This review summarizes why the sexes can evolve different life-history strategies. The scale of the sex skew is then discussed and its magnitude compared between taxonomic groups, laboratory and field studies, and through time. We discuss the consequences of this sex skew for evolutionary and ecological research. In particular, this sex bias means that we cannot test some core evolutionary theory. Additionally, this skew could obscure or drive trends in data and hinder our ability to develop effective conservation strategies. We finally highlight some ways through which this skew could be addressed to help us better understand broad patterns in life-history strategies.


Assuntos
Evolução Biológica , Reprodução , Animais , Feminino , Masculino , Fenótipo , Caracteres Sexuais , Comportamento Sexual Animal
7.
Am Nat ; 200(1): E16-E35, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35737989

RESUMO

AbstractUnderstanding how a species' life history affects its capacity to cope with environmental changes is important in the context of rapid climate changes. Reinterpreting previous results from a well-developed theoretical framework, we show that a trade-off exists between a species' ability to genetically adapt to long-term gradual environmental changes and its ability to demographically resist short-term environmental perturbations, causing variation in its vital rates. Surprisingly, this important insight has not been made formally explicit before. Choosing archetypal life histories along the fast-slow pace-of-life continuum and modeling their eco-evolutionary dynamics, we further show that long-lived species have larger demographic robustness to interannual fluctuations but limited trait evolutionary responses in gradually changing environments. In contrast, short-lived species had larger evolvability but reduced demographic robustness. This trade-off bears heavily on extinction probabilities of populations tracking fast trait changes in stochastic environments. Faster trait evolution in short-lived species came at the expense of their higher sensitivity to short-term fluctuations, causing higher extinction rates than for long-lived species. Long-lived species persisted better on short timescales but built maladaptation and an extinction debt over time. This work shows how modeling species' eco-evolutionary dynamics can help to assess species vulnerability to environmental changes.


Assuntos
Adaptação Fisiológica , Mudança Climática , Evolução Biológica , Fenótipo
8.
Am Nat ; 199(5): 679-690, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35472024

RESUMO

AbstractIn most socially structured populations, the formation of new groups depends on the survival and reproduction of dispersing individuals. Quantifying vital rates in dispersers, however, is difficult because of the logistic challenges of following wide-ranging animals. Here, using data from free-ranging meerkats (Suricata suricatta), we estimate survival and reproduction of dispersing females and compare these estimates to data for established residents. Meerkat groups consist of a dominant pair and several subordinate helpers. Female helpers are evicted from their resident groups by the dominant female, allowing her to monopolize reproduction, and evicted females may form small dispersing coalitions. We show that, as in established resident groups, one female is behaviorally dominant in parties of dispersing females. During dispersal and the first 4 months after new group formation, survival is lower for all females compared with established resident groups. At the same time, subordinates in disperser groups have higher birth rates than those in established groups, which rarely breed successfully. This may partly offset the survival costs of dispersal to subordinate females. Further studies of dispersal based on direct observation of dispersing animals are needed to explore the costs and benefits of dispersal in species with contrasting breeding systems.


Assuntos
Herpestidae , Animais , Feminino , Reprodução
9.
Trends Plant Sci ; 27(7): 637-645, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35039247

RESUMO

The growing demand for timber and the boom in massive tree-planting programs could mean the spreading of mismanaged tree plantations worldwide. Here, we apply the concept of ecological intensification to forestry systems as a viable biodiversity-focused strategy that could be critical to develop productive, yet sustainable, tree plantations. Tree plantations can be highly productive if tree species are properly combined to complement their ecological functions. Simultaneously considering soil biodiversity and animal-mediated biocontrol will be critical to minimize the reliance on external inputs. Integrating genetic, functional, and demographic diversity across heterogeneous landscapes should improve resilience under climate change. Designing ecologically intensified plantations will mean breaking the timber productivity versus conservation dichotomy and assuring the maintenance of key ecosystem services at safe levels.


Assuntos
Ecossistema , Árvores , Animais , Biodiversidade , Conservação dos Recursos Naturais , Agricultura Florestal , Florestas
10.
J Anim Ecol ; 90(6): 1398-1407, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33825186

RESUMO

Approximately 25% of mammals are currently threatened with extinction, a risk that is amplified under climate change. Species persistence under climate change is determined by the combined effects of climatic factors on multiple demographic rates (survival, development and reproduction), and hence, population dynamics. Thus, to quantify which species and regions on Earth are most vulnerable to climate-driven extinction, a global understanding of how different demographic rates respond to climate is urgently needed. Here, we perform a systematic review of literature on demographic responses to climate, focusing on terrestrial mammals, for which extensive demographic data are available. To assess the full spectrum of responses, we synthesize information from studies that quantitatively link climate to multiple demographic rates. We find only 106 such studies, corresponding to 87 mammal species. These 87 species constitute <1% of all terrestrial mammals. Our synthesis reveals a strong mismatch between the locations of demographic studies and the regions and taxa currently recognized as most vulnerable to climate change. Surprisingly, for most mammals and regions sensitive to climate change, holistic demographic responses to climate remain unknown. At the same time, we reveal that filling this knowledge gap is critical as the effects of climate change will operate via complex demographic mechanisms: a vast majority of mammal populations display projected increases in some demographic rates but declines in others, often depending on the specific environmental context, complicating simple projections of population fates. Assessments of population viability under climate change are in critical need to gather data that account for multiple demographic responses, and coordinated actions to assess demography holistically should be prioritized for mammals and other taxa.


Assuntos
Mudança Climática , Mamíferos , Animais , Dinâmica Populacional
11.
Nat Commun ; 12(1): 1824, 2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33758189

RESUMO

There is an urgent need to synthesize the state of our knowledge on plant responses to climate. The availability of open-access data provide opportunities to examine quantitative generalizations regarding which biomes and species are most responsive to climate drivers. Here, we synthesize time series of structured population models from 162 populations of 62 plants, mostly herbaceous species from temperate biomes, to link plant population growth rates (λ) to precipitation and temperature drivers. We expect: (1) more pronounced demographic responses to precipitation than temperature, especially in arid biomes; and (2) a higher climate sensitivity in short-lived rather than long-lived species. We find that precipitation anomalies have a nearly three-fold larger effect on λ than temperature. Species with shorter generation time have much stronger absolute responses to climate anomalies. We conclude that key species-level traits can predict plant population responses to climate, and discuss the relevance of this generalization for conservation planning.


Assuntos
Mudança Climática , Desenvolvimento Vegetal/fisiologia , Plantas/efeitos adversos , Dinâmica Populacional/estatística & dados numéricos , Variação Biológica da População/fisiologia , Clima , Bases de Dados Factuais , Ecossistema , Modelos Estatísticos , Chuva , Análise de Regressão , Temperatura
12.
J Chem Ecol ; 47(1): 73-86, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33417071

RESUMO

Most carnivorous plants show a conspicuous separation between flowers and leaf-traps, which has been interpreted as an adaptive response to minimize pollinator-prey conflicts which will reduce fitness. Here, we used the carnivorous subshrub Drosophyllum lusitanicum (Drosophyllaceae) to explore if and how carnivorous plants with minimal physical separation of flower and trap avoid or reduce a likely conflict of pollinator and prey. We carried out an extensive field survey in the Aljibe Mountains, at the European side of the Strait of Gibraltar, of pollinating and prey insects of D. lusitanicum. We also performed a detailed analysis of flower and leaf volatile and semi-volatile organic compounds (VOCs and SVOCs, respectively) by direct thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) to ascertain whether this species shows different VOC/SVOC profiles in flowers and leaf-traps that might attract pollinators and prey, respectively. Our results show a low overlap between pollinator and prey groups as well as clear differences in the relative abundance of VOCs and SVOCs between flowers and leaf-traps. Coleopterans and hymenopterans were the most represented groups of floral visitors, whereas dipterans were the most diverse group of prey insects. Regarding VOCs and SVOCs, while aldehydes and carboxylic acids presented higher relative contents in leaf-traps, alkanes and plumbagin were the main VOC/SVOC compounds detected in flowers. We conclude that D. lusitanicum, despite its minimal flower-trap separation, does not seem to present a marked pollinator-prey conflict. Differences in the VOCs and SVOCs produced by flowers and leaf-traps may help explain the conspicuous differences between pollinator and prey guilds.


Assuntos
Planta Carnívora/química , Insetos , Polinização , Compostos Orgânicos Voláteis/análise , Animais , Planta Carnívora/fisiologia , Flores/química , Folhas de Planta/química , Mucilagem Vegetal/química
13.
Ecol Lett ; 23(4): 588-597, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31970918

RESUMO

Natural populations are exposed to seasonal variation in environmental factors that simultaneously affect several demographic rates (survival, development and reproduction). The resulting covariation in these rates determines population dynamics, but accounting for its numerous biotic and abiotic drivers is a significant challenge. Here, we use a factor-analytic approach to capture partially unobserved drivers of seasonal population dynamics. We use 40 years of individual-based demography from yellow-bellied marmots (Marmota flaviventer) to fit and project population models that account for seasonal demographic covariation using a latent variable. We show that this latent variable, by producing positive covariation among winter demographic rates, depicts a measure of environmental quality. Simultaneously, negative responses of winter survival and reproductive-status change to declining environmental quality result in a higher risk of population quasi-extinction, regardless of summer demography where recruitment takes place. We demonstrate how complex environmental processes can be summarized to understand population persistence in seasonal environments.


Assuntos
Clima , Marmota , Animais , Demografia , Dinâmica Populacional , Estações do Ano
14.
Ann Bot ; 124(1): 65-76, 2019 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-31329814

RESUMO

BACKGROUND AND AIMS: Little is known about the evolutionary and ecological drivers of carnivory in plants, particularly for those terrestrial species that do not occur in typical swamp or bog habitats. The Mediterranean endemic Drosophyllum lusitanicum (Drosophyllaceae) is one of very few terrestrial carnivorous plant species outside of Australia to occur in seasonally dry, fire-prone habitats, and is thus an ecological rarity. Here we assess the nutritional benefits of prey capture for D. lusitanicum under differing levels of soil fertility in situ. METHODS: We measured the total nitrogen and stable nitrogen and carbon isotope ratios of D. lusitanicum leaves, neighbouring non-carnivorous plant leaves, and groups of insect prey in three populations in southern Spain. We calculated trophic enrichment (ε15N) and estimated the proportion of prey-derived nitrogen (%Nprey) in D. lusitanicum leaves, and related these factors to soil chemistry parameters measured at each site. KEY RESULTS: In all three populations studied, D. lusitanicum plants were significantly isotopically enriched compared with neighbouring non-carnivorous plants. We estimated that D. lusitanicum gain ~36 %Nprey at the Puerto de Gáliz site, ~54 %Nprey at the Sierra Carbonera site and ~75 %Nprey at the Montera del Torero site. Enrichment in N isotope (ε15N) differed considerably among sites; however, it was not found to be significantly related to log10(soil N), log10(soil P) or log10(soil K). CONCLUSIONS: Drosophyllum lusitanicum individuals gain a significant nutritional benefit from captured prey in their natural habitat, exhibiting proportions of prey-derived nitrogen that are similar to those recorded for carnivorous plants occurring in more mesic environments. This study adds to the growing body of literature confirming that carnivory is a highly beneficial nutritional strategy not only in mesic habitats but also in seasonally dry environments, and provides insights to inform conservation strategies for D. lusitanicum in situ.


Assuntos
Carnivoridade , Áreas Alagadas , Animais , Austrália , Plantas , Espanha
15.
Science ; 363(6427): 631-635, 2019 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-30733418

RESUMO

Species in extreme habitats increasingly face changes in seasonal climate, but the demographic mechanisms through which these changes affect population persistence remain unknown. We investigated how changes in seasonal rainfall and temperature influence vital rates and viability of an arid environment specialist, the Kalahari meerkat, through effects on body mass. We show that climate change-induced reduction in adult mass in the prebreeding season would decrease fecundity during the breeding season and increase extinction risk, particularly at low population densities. In contrast, a warmer nonbreeding season resulting in increased mass and survival would buffer negative effects of reduced rainfall during the breeding season, ensuring persistence. Because most ecosystems undergo seasonal climate variations, a full understanding of species vulnerability to global change relies on linking seasonal trait and population dynamics.


Assuntos
Adaptação Fisiológica , Ambientes Extremos , Fertilidade , Herpestidae/fisiologia , Animais , Botsuana , Mudança Climática , Feminino , Masculino , Densidade Demográfica , Dinâmica Populacional , Chuva , Estações do Ano , Temperatura
16.
Water Res ; 139: 19-29, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29621714

RESUMO

Microalgae biotechnology is a promising tool for many applications, including the elimination of nutrients and other contaminants from wastewater. In this work, we measured the removal efficiency of two wastewater treatment processes: an activated-sludge based conventional process and another based on microalgae biotechnology using high-rate algae ponds (HRAPs). The latter was tested using two different configurations. In the first one, HRAPs were placed after an UASB reactor and used as a tertiary treatment to remove nutrients. In the second, the UASB reactor was disconnected so the HRAPs were directly fed with pretreated wastewater. Additional treatment was performed using dissolved air flotation (DAF). The performances of both configurations (UASB-HRAP and HRAP-DAF) were compared to that of the conventional line including primary and secondary biological treatments and operating in parallel within the same wastewater treatment plant (WWTP). Sixty-four out of 81 target PhACs were detected in the influent of the WWTP, at an average concentration of 223 µg L-1, whereas 55 and 54 were measured in the conventional (14 µg L-1) and non-conventional (17 µg L-1) effluents. Average removal efficiencies were similar (94 vs. 92%) for both treatment lines when comparing total PhACs concentrations. The compositional patterns of the resulting effluents, however, were not, suggesting the occurrence of differential removal mechanisms depending on the chemicals and wastewater treatments considered. Highly consumed compounds such as ibuprofen and acetaminophen were predominant in the non-conventional effluent (>1 µg L-1), denoting lower removal than in the conventional line. On the other hand, elimination of diclofenac and some specific antibiotics and diuretics (e.g., hydrochlorothiazide) was between 15 and 50% higher using HRAPs. Overall, the efficiency of the microalgae technology removing PhACs was found to be comparable to that used in conventional WWTPs. This, combined with a higher efficiency removing nutrients, shows the potential of HRAP technology for wastewater treatment as an alternative (or addition as tertiary treatment) to more conventional approaches based on activated sludge.


Assuntos
Microalgas/metabolismo , Preparações Farmacêuticas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Reatores Biológicos , Cidades , Lagoas , Águas Residuárias
17.
Ecol Lett ; 21(2): 275-286, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29266843

RESUMO

Temporal autocorrelation in demographic processes is an important aspect of population dynamics, but a comprehensive examination of its effects on different life-history strategies is lacking. We use matrix population models from 454 plant and animal populations to simulate stochastic population growth rates (log λs ) under different temporal autocorrelations in demographic rates, using simulated and observed covariation among rates. We then test for differences in sensitivities, or changes of log λs to changes in autocorrelation among two major axes of life-history strategies, obtained from phylogenetically informed principal component analysis: the fast-slow and reproductive-strategy continua. Fast life histories exhibit highest sensitivities to simulated autocorrelation in demographic rates across reproductive strategies. Slow life histories are less sensitive to temporal autocorrelation, but their sensitivities increase among highly iteroparous species. We provide cross-taxonomic evidence that changes in the autocorrelation of environmental variation may affect a wide range of species, depending on complex interactions of life-history strategies.


Assuntos
Plantas , Dinâmica Populacional , Animais , Traços de História de Vida , Reprodução
18.
AoB Plants ; 9(5): plx036, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28948008

RESUMO

Fire is a topical issue in the management of many ecosystems globally that face a drying climate. Understanding the role of fire in such ecosystems is critical to inform appropriate management practices, particularly in the case of rare and ecologically specialized species. The Mediterranean heathlands are highly fire-prone and occur in a biodiversity hotspot increasingly threatened by human activities, and determining the reproductive thresholds of at-risk heathland species is critical to ensuring the success of future conservation initiatives. This study examined the germination biology of the threatened carnivorous subshrub Drosophyllum lusitanicum, with specific focus on the role of fire-related cues (heat and smoke) in combination with seasonal temperatures and moisture conditions to determine how these factors regulate seed dormancy and germination. We found that D. lusitanicum produces water-permeable, physiologically dormant seeds with a fully developed, capitate embryo that when fresh (~1 month old) and without treatment germinate to 20-40 % within 4-8 weeks. Seeds possess a restricted thermal window (15-20 °C) for germination and a neutral photoblastic response. Seed dormancy was overcome through precision nicking of the seed coat (>90 % germination) or by short exposure to dry heat (80 or 100 °C) for 5-30 min (60-100 % germination). We propose seedling emergence from the soil seed bank may be cued by the passage of fire, or by soil disturbance from the movement and browsing of animals. Long-term population viability is likely to be contingent upon appropriate management of the persistent soil seed bank, as well as the adequate management of key ecological disturbances such as fire. Drosophyllum lusitanicum faces an increasingly bleak future in the absence of conservation and management initiatives aimed at reducing habitat fragmentation in heathlands and aligning fire management and livestock practices with biodiversity outcomes.

19.
Sci Total Environ ; 605-606: 770-783, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28679121

RESUMO

This study is focused on the Guadalete River basin (SW, Spain), where extreme weather conditions have become common, with and alternation between periods of drought and extreme rainfall events. Combined sewer overflows (CSOs) occur when heavy rainfall events exceed the capacity of the wastewater treatment plants (WWTP), as well as pollution episodes in parts of the basin due to uncontrolled sewage spills and the use of reclaimed water and sludge from the local WWTP. The sampling was carried out along two seasons and three campaigns during dry (March 2007) and extreme rainfall (April and December 2010) in the Guadalete River, alluvial aquifer and Jerez de la Frontera aquifer. Results showed minimum concentrations for synthetic surfactants in groundwater (<37.4µg·L-1) during the first campaign (dry weather conditions), whereas groundwater contaminants increased in December 2010 as the heavy rainfall caused the river to overflow. In surface water, surfactant concentrations showed similar trends to groundwater observations. In addition to surfactants, pharmaceuticals and personal care products (PPCPs) were analyzed in the third campaign, 22 of which were detected in surface waters. Two fragrances (OTNE and galaxolide) and one analgesic/anti-inflammatory (ibuprofen) were the most abundant PPCPs (up to 6540, 2748 and 1747ng·L-1, respectively). Regarding groundwater, most PPCPs were detected in Jerez de la Frontera aquifer, where a synthetic fragrance (OTNE) was predominant (up to 1285ng·L-1).

20.
Am J Bot ; 102(5): 689-94, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-26022483

RESUMO

PREMISE OF THE STUDY: Carnivorous plants have unusually modified leaves to trap insects as an adaptation to low-nutrient environments. Disparate mechanisms have been suggested as luring traits to attract prey insects into their deadly leaves, ranging from very elaborate to none at all. Drosophyllum lusitanicum is a rare carnivorous plant with a common flypaper-trap mechanism. Here we tested whether Drosophyllum plants lure prey insects into their leaves or they act just as passive traps. METHODS: We compared prey capture between live, potted plants and Drosophyllum-shaped artificial mimics coated with odorless glue. Since this species is insect-pollinated, we also explored the possible existence of a pollinator-prey conflict by quantifying the similarity between the pollination and prey guilds in a natural population. All experiments were done in southern Spain. KEY RESULTS: The sticky leaves of Drosophyllum captured significantly more prey than mimics, particularly small dipterans. Prey attraction, likely exerted by scent or visual cues, seems to be unrelated to pollinator attraction by flowers, as inferred from the low similarity between pollinator and prey insect faunas found in this species. CONCLUSIONS: Our results illustrate the effectiveness of this carnivorous species at attracting insects to their flypaper-trap leaves.


Assuntos
Cadeia Alimentar , Insetos/fisiologia , Magnoliopsida/fisiologia , Polinização , Animais , Droseraceae/fisiologia , Espanha
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