The Northern Wheatear (Oenanthe oenanthe, including the nominate and the two subspecies O. o. leucorhoa and O. o. libanotica) and the Seebohm's Wheatear (Oenanthe seebohmi) are today regarded as two ...distinct species. Before, all four taxa were regarded as four subspecies of the Northern Wheatear. Their classification has exclusively been based on ecological and morphological traits, while their molecular characterization is still missing. With this study, we used next-generation sequencing to assemble 117 complete mitochondrial genomes covering O. o. oenanthe, O. o. leucorhoa and O. seebohmi. We compared the resolution power of each individual mitochondrial marker and concatenated marker sets to reconstruct the phylogeny and estimate speciation times of three taxa. Moreover, we tried to identify the origin of migratory wheatears caught on Helgoland (Germany) and on Crete (Greece). Mitogenome analysis revealed two different ancient lineages that separated around 400,000 years ago. Both lineages consisted of a mix of subspecies and species. The phylogenetic trees, as well as haplotype networks are incongruent with the present morphology-based classification. Mitogenome could not distinguish these presumed species. The genetic panmixia among present populations and taxa might be the consequence of mitochondrial introgression between ancient wheatear populations.
Effects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed ...the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (
n
== 1350), farm (
n
== 270), and European-region (
n
== 9) scale. We partitioned diversity into its additive components αα, ββ, and γγ, and assessed the relative contribution of ββ diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to ββ diversity on larger scales up to the farm and region level, and thereby was an indicator of farm- and region-wide biodiversity losses. At the scale of farms (12.83-–20.52%%) and regions (68.34-–80.18%%), ββ diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of αα diversity decreased with AI, while relative importance of ββ diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agri-environmental schemes in agroecosystems.
During the last 50 years, agricultural intensification has caused many wild plant and animal species to go extinct regionally or nationally and has profoundly changed the functioning of ...agro-ecosystems. Agricultural intensification has many components, such as loss of landscape elements, enlarged farm and field sizes and larger inputs of fertilizer and pesticides. However, very little is known about the relative contribution of these variables to the large-scale negative effects on biodiversity. In this study, we disentangled the impacts of various components of agricultural intensification on species diversity of wild plants, carabids and ground-nesting farmland birds and on the biological control of aphids.
In a Europe-wide study in eight West and East European countries, we found important negative effects of agricultural intensification on wild plant, carabid and bird species diversity and on the potential for biological pest control, as estimated from the number of aphids taken by predators. Of the 13 components of intensification we measured, use of insecticides and fungicides had consistent negative effects on biodiversity. Insecticides also reduced the biological control potential. Organic farming and other agri-environment schemes aiming to mitigate the negative effects of intensive farming on biodiversity did increase the diversity of wild plant and carabid species, but – contrary to our expectations – not the diversity of breeding birds.
We conclude that despite decades of European policy to ban harmful pesticides, the negative effects of pesticides on wild plant and animal species persist, at the same time reducing the opportunities for biological pest control. If biodiversity is to be restored in Europe and opportunities are to be created for crop production utilizing biodiversity-based ecosystem services such as biological pest control, there must be a Europe-wide shift towards farming with minimal use of pesticides over large areas.
Durch die Intensivierung der Landwirtschaft in den letzten 50 Jahren sind viele Pflanzen- und Tierarten auf regionaler und nationaler Ebene ausgestorben und ist die Funktion des Agrarökosystems beeinträchtigt. Die landwirtschaftliche Intensivierung umfasst viele verschiedene Faktoren, wie zum Beispiel die Homogenisierung der Landschaft, die Vergrößerung von landwirtschaftlichen Betrieben und Äckern und den zunehmenden Gebrauch von Düngern und Pestiziden. Über den relativen Beitrag der einzelnen Faktoren zu den weitgehenden Auswirkungen der Intensivierung auf die Biodiversität ist jedoch wenig bekannt. In dieser Studie haben wir den Einfluss dieser verschiedenen Faktoren auf die Diversität von Pflanzen, Laufkäfern und bodenbrütenden Ackervögeln sowie auf die biologische Schädlingsbekämpfung von Blattläusen, entwirrt.
In einer europaweiten Studie, in acht West- und Ost-Europäischen Ländern, haben wir weitgehende, negative Effekte der landwirtschaftlichen Intensivierung auf Pflanzen, Laufkäfer, bodenbrütende Ackervögel und die biologische Schädlingsbekämpfung - die Anzahl durch natürliche Feinde gefressener Blattläuse - gefunden. Von den dreizehn Faktoren der landwirtschaftlichen Intensivierung die wir gemessen haben, hatte der Gebrauch von Insektiziden und Fungiziden konsequent negative Effekte auf die Biodiversität. Insektizide reduzierten ebenfalls die biologische Schädlingsbekämpfung. Organische Bewirtschaftung und andere Formen von Ökologischem Ausgleich, die zum Ziel haben, die negativen Effekte der Intensivierung auf Biodiversität abzuschwächen, erhöhten die Pflanzen- und Laufkäferdiversität, jedoch – entgegen unseren Erwartungen - nicht die Diversität der Brutvögel.
Wir stellen fest, dass trotz jahrzehntelanger europäischer Politik gegen schädliche Pestizide, die negativen Auswirkungen von Pestiziden auf Pflanzen- und Tierarten andauern und damit auch die Möglichkeit biologischer Schädlingsbekämpfung abnimmt. Wenn die Biodiversität in Europa erhalten werden soll und die Chance auf biodiversitätsgebundenen Ökosystemfunktionen, wie biologische Schädlingsbekämpfung, beruhenden Ackerbau geschaffen werden soll, ist eine europaweite Veränderung zu einer Bewirtschaftung mit minimalem Gebrauch von Pestiziden über eine große Fläche notwendig.
1. Studies, mainly from the UK, show that many farmland birds have declined as a result of recent agricultural intensification. We tested this idea by analysing farmland bird population trends in ...Sweden, a country displaying less dramatic agricultural changes and less intensive agriculture. Specifically we investigated whether (i) farmland specialists have declined more than generalists, (ii) population declines in Sweden are less marked than in England and (iii) Swedish population trends are associated with changes in the amount of autumn-sown crops, and inputs of pesticides and fertilizers. 2. Data on population trends for 21 farmland bird species collected from the Swedish Breeding Bird Survey 1976-2001 were analysed in relation to agricultural changes in Sweden. 3. Fifteen (71%) farmland bird species declined significantly in number (P < 0.05) over the 26 years. Farmland specialists displayed a significantly stronger average decline (55%) as a group than farmland generalists (7%). For seven species the declines were significantly steeper between 1976 and 1988 than between 1988 and 2001. 4. Farmland bird populations have declined at least as much in Sweden as in England. Several specialist species displayed similar temporal patterns in population change in both countries. 5. The area of autumn-sown crops has remained stable in Sweden, whereas use of pesticides and fertilizers has declined. There are no clear associations between these factors and observed farmland bird population declines. 6. The similarities in bird population trends in Sweden and England, despite large differences in patterns of agricultural change in Sweden and England, may be explained by: (i) common wintering grounds, (ii) similar negative effects of agricultural intensification (England) and intensification/abandonment (Sweden) and (iii) a simultaneous loss of landscape heterogeneity. 7. Synthesis and applications. Farmland birds in Sweden have declined by at least as much as in England, despite clear differences between the two countries in the degree of agricultural intensification over the last 30 years. We suggest that the marked declines in Swedish populations are caused by (i) the dual negative effects of intensification and abandonment of farmland at breeding grounds, and (ii) Swedish populations partly sharing wintering grounds with English populations. We conclude that agri-environmental schemes need to be flexible enough to address the negative effects both of intensification and the abandonment of farming. In addition, our results emphasize that farmland bird conservation is an issue without country borders.
1. The widespread declines of farmland birds have generally been linked to agricultural intensification. We tested the hypotheses that (i) changes in agricultural policy, through its effects on ...agricultural intensification and (ii) regional differences in agricultural intensification affect temporal and spatial population trends of farmland birds in Sweden. 2. We analysed regional bird population trends (1976-2003) for seven common farmland bird species: the migratory lapwing Vanellus vanellus, skylark Alauda arvensis, starling Sturnus vulgaris and linnet Carduelis cannabina and the resident tree sparrow Passer montanus, house sparrow P. domesticus and yellowhammer Emberiza citrinella. We identified three periods of agricultural policy in Sweden between 1976 and 2003: the intensification period (i.e. 1976-87; promoting increased production), the set-aside period (1987-95; promoting extensification of farming) and the Common Agricultural Policy (CAP) period (1995-2003; promoting increased production). Population trends were compared between three types of Swedish farmlands: open plains (intensive farming with a marked intensification), mosaic farmlands (i.e. farmland-dominated forest mosaics, less intensive farming, but show moderate intensification) and forest regions (i.e. forest-dominated farmlands with low intensity farming and extensification/abandonment). 3. The four migrants displayed clear significant trend switches between the policy periods, with declines in the 'intensification period' and the 'CAP period' and less negative or even positive population trends in the 'set-aside period'. The population trends of the three resident species showed no clear pattern in relation to agricultural policy periods. 4. All species except tree sparrow displayed significantly different population trends between farmland regions. Four species (lapwing, skylark, linnet and house sparrow) declined most in the open plains and the forest regions, whereas two species (starling and yellowhammer) declined most in the mosaic farmlands. 5. Synthesis and applications. Large-scale changes in agriculture policy have a strong potential to change the present poor state of farmland biodiversity as shown by the generally positive population trends in the 'set-aside period'. It also suggests extensification to be beneficial to farmland birds. However, in regions of low profitability and an already ongoing extensification, a further extensification will lead to loss of both farmland habitat and bird diversity. In such regions mixed farming needs to be retained and hence should be supported.
Agricultural intensification reduces the taxonomic diversity of bird communities, but its influence on functional diversity has been less studied. Here, we analyze the response of functional ...diversity of different cereal farmland bird communities across Europe to a gradient of agricultural intensification. We collected bibliographical information on life history traits (i.e. body mass, brain size, age of sexual maturity, clutch size, number of clutches, lifespan) of 30 species of birds recorded during field surveys in eight European countries. The index "brood value" was calculated to know each species' level of reproductive investment per clutch. Intensification gradients at two spatial scales were obtained from field data through PCA, related to management practices at the field scale and the variation in structure and composition of farmland at the landscape scale respectively. We calculated the functional diversity index (FD) and the community-weighted mean (CWM) for each trait and sampling area, and linear mixed models in relation to the two intensification gradients were performed. Results showed that stronger intensification at the field level favors the assembly of shorter-lived communities and bird species with smaller relative brain sizes, also decreasing overall trait diversity. It also restricts the range of strategies for parental investment, reducing the functional diversity of the brood value index. More intensive field management would favor bird communities dominated by generalist and even introduced and/or managed hunting species, while putting at risk those farmland- and grassland-adapted species, typically more associated with the provision of ecosystem services. This highlights the relevance of field management (agrochemicals use, ploughing frequency) for the functional composition of bird communities and the conservation of farmland biodiversity. These findings add to existing knowledge on how species' pace of life and cognitive capacity interact with drivers of global change, such as agricultural intensification.
Estimating the contribution of demographic parameters to changes in population growth is essential for understanding why populations fluctuate. Integrated population models (IPMs) offer a possibility ...to estimate the contributions of additional demographic parameters, for which no data have been explicitly collected—typically immigration. Such parameters are often subsequently highlighted as important drivers of population growth. Yet, accuracy in estimating their temporal variation, and consequently their contribution to changes in population growth rate, has not been investigated.
To quantify the magnitude and cause of potential biases when estimating the contribution of immigration using IPMs, we simulated data (using northern wheatear Oenanthe oenanthe population estimates) from controlled scenarios to examine potential biases and how they depend on IPM parameterization, formulation of priors, the level of temporal variation in immigration and sample size. We also used empirical data on populations with known rates of immigration: Soay sheep Ovis aries and Mauritius kestrel Falco punctatus with zero immigration and grey wolf Canis lupus in Scandinavia with near‐zero immigration.
IPMs strongly overestimated the contribution of immigration to changes in population growth in scenarios when immigration was simulated with zero temporal variation (proportion of variance attributed to immigration = 63% for the more constrained formulation and real sample size) and in the wild populations, where the true number of immigrants was zero or near‐zero (kestrel 19.1%–98.2%, sheep 4.2%–36.1% and wolf 84.0%–99.2%). Although the estimation of the contribution of immigration in the simulation study became more accurate with increasing temporal variation and sample size, it was often not possible to distinguish between an accurate estimation from data with high temporal variation versus an overestimation from data with low temporal variation. Unrealistically, large sample sizes may be required to estimate the contribution of immigration well.
To minimize the risk of overestimating the contribution of immigration (or any additional parameter) in IPMs, we recommend to: (a) look for evidence of variation in immigration before investigating its contribution to population growth, (b) simulate and model data for comparison to the real data and (c) use explicit data on immigration when possible.
Résumé
Estimer la contribution des paramètres démographiques aux changements de croissance des populations est essentiel pour comprendre pourquoi les populations fluctuent. Les modèles de population intégrés (IPMs) offrent la possibilité d'estimer la contribution de paramètres démographiques additionnels, pour lesquels aucune donnée n'est explicitement collectée : typiquement l'immigration. De tels paramètres sont souvent mis en évidence comme étant des moteurs importants de la croissance des populations. Toutefois, la justesse de l'estimation de leur variation temporelle, et donc de leur contribution aux changements du taux de croissance, n'a pas été examinée.
Pour quantifier la magnitude et la cause de biais potentiels lors de l'estimation de la contribution de l'immigration avec des IPMs, nous avons simulé des données (en utilisant des estimations issues d'une population de traquet motteux Oenanthe oenanthe) afin d'examiner ces biais en fonction de la paramétrisation de l’IPM, la formulation des priors, le degré de variation temporelle de l'immigration et la taille d’échantillon. Nous avons également utilisé des données empiriques issues de populations aux taux d'immigration connus : le mouton de Soay Ovis aries et la crécerelle de Maurice Falco punctatus sans immigration et le loup gris Canis lupus en Scandinavie avec une immigration quasi‐nulle.
Les IPMs surestiment fortement la contribution de l'immigration aux changements de croissance des populations pour les scénarios où l'immigration était simulée sans variation temporelle (proportion de variance attribuée à l'immigration =63% pour la formulation la plus contrainte et la taille d’échantillon réelle) et pour les populations sauvages, où le vrai nombre d'immigrants était nul ou quasi‐nul (crécerelle 19.1%–98.2%, mouton 4.2%‐36.1%, loup 84.0%–99.2%). Même si l'estimation de la contribution de l'immigration s'améliore lorsque la variation temporelle ou la taille d’échantillon augmentent, il était généralement impossible de distinguer entre une estimation correcte issue de donnés avec haute variation temporelle versus une surestimation issue de donnés avec faible variation temporelle. Seules des tailles d’échantillon déraisonnablement élevées pourraient permettre d'estimer précisément la contribution de l'immigration.
Pour minimiser le risque de surestimer la contribution de l'immigration (ou autre paramètre additionnel) avec des IPMs, nous recommandons (i) de rechercher des preuves de variation de l'immigration avant d’étudier sa contribution à la croissance des populations, (ii) de simuler et modéliser des donnés pour comparer avec des données réelles et (iii) d'utiliser des donnés explicites sur l'immigrations lorsque cela est possible.
The delivery of rigorous and unbiased evidence on the effects of interventions lay at the heart of the scientific method. Here we examine scientific papers evaluating agri‐environment schemes, the ...principal instrument to mitigate farmland biodiversity declines worldwide. Despite previous warnings about rudimentary study designs in this field, we found that the majority of studies published between 2008 and 2017 still lack robust study designs to strictly evaluate intervention effects. Potential sources of bias that arise from the correlative nature are rarely mentioned, and results are still promoted by using a causal language. This lack of robust study designs likely results from poor integration of research and policy, while the erroneous use of causal language and an unwillingness to discuss bias may stem from publication pressures. We conclude that scientific reporting and discussion of study limitations in intervention research must improve and propose some practices toward this goal.
European green agricultural policies have been relaxed to allow cultivation of fallow land to produce animal feed and meet shortfalls in exports from Ukraine and Russia. However, conversion of ...semi-natural habitats will disproportionately impact long term biodiversity and food security.In their Comment in @CommsEarth, Manuel Morales and colleagues argue that we must act now to protect green agricultural policies in the EU to ensure food security in the future.
•Studying drivers of invasive plant species spread demands data on their distribution.•We used Google Street View as a new source of data to track invasive goldenrods.•We validated our remote method ...by comparing its outputs with a matched field study.•Our method performed well in detecting studied species along roadsides.•We suggest it may be used in detecting, tracking and managing invasive plant species.
Invasive alien plants are considered a major driver of global biodiversity loss. Therefore, there is a huge demand of spatial and temporal data on their distribution for investigating possible drivers of species invasions and for predictions of future distributions. We use Google Street View imagery (GSV) as a new source of spatial and temporal data. GSV provides millions of panoramic views along road networks worldwide allowing for the identification of many plant species, including invasive ones. Thus, GSV has a great potential to support ecological research in documenting species distribution, but reliable validation of its precision and accuracy is lacking. Here, we describe and evaluate an approach using GSV to visually track the spread of invasive alien plants, the North American goldenrods (Solidago canadensis and S. gigantea) occurring abundantly along road network in Poland (Central Europe). We determined presence/absence of the species along 160 randomly selected transects of a length of 500 m by visual inspection of GSV images and compared it with field surveys at the same transects. We show that the occurrence of goldenrods in GSV is a reliable predictor of their occurrence in the wild. Sampling parameters, like road width, season when GSV pictures were taken and number of months elapsed since taking the GSV pictures, did not change the correlation between outputs of the two methods (GSV and field sampling). Furthermore, both the occurrence of goldenrods observed in the field and their occurrence in GSV have similar relations to habitat characteristics investigated (the same direction of relationship and similar effect size). We suggest Google Street View images may be an additional tool to be used in the detection and tracking of the spread of invasive alien plants along roadsides. The approach may be useful in assessing temporal changes in roadside vegetation and managing problematic plant species across large spatial scales and may contribute to the further development of more efficient sampling methods in ecological studies.
PDF
