| 1. |
- Olle, Jonsson B., et al.
(författare)
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Allozyme diversity and geographic variation in the widespread coastal sedge, Carex arenaria
- 2000
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 6:2, s. 65-80
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Tidskriftsartikel (refereegranskat)abstract
- Allozyme electrophoresis was used to investigate the structure of genetic variation in the rhizomatous coastal sedge, Carex arenaria, throughout its European range - from the SW Iberian peninsula to the Baltic region. Material was sampled from 77 sites in five geographic regions. Nine of the 13 investigated loci were polymorphic in the total material and there were interregional differences in the number of polymorphic loci per site and the percentage of variable sites. In the Scandinavia/Baltic region only 61% of the sites contained at least one locus with more than one allele, whereas all the British and SW Iberian sites were variable. There was a general tendency for the regional frequencies of the less common alleles at individual loci to decline from SW to NE. The mean (over loci and sites) within-site gene diversity (H(site)) was 0.064 (in calculations based on the number of observed multilocus allozyme genotypes within each sampling site). Although there was considerable variation between geographically adjacent sites, within-site diversity showed a general decrease from SW to NE in Europe. There were significant differences in within-region gene diversity (H(reg)) for the four most variable loci between the five regions. H(reg) generally decreased from SW to NE Europe and most loci showed the highest diversity in the SW Iberian peninsula and the Bay of Biscay regions. The mean (over loci) gene diversity in the total material (H(tot)) was 0.070 and the levels of diversity in Carex arenaria are substantially lower than is usual in rhizomatous sedges. The within-site, between-site and between-regional components of the total diversity were 92.4%, 2.5% and 5.1%, respectively. The low levels of overall gene diversity in C. arenaria and the successive decrease in diversity from SW to NE are interpreted in terms of the species' history of post-glacial spread into northern Europe. Despite the overall northwards decrease in diversity, the widespread occurrence of less common alleles and the lack of regional deviations from Hardy-Weinberg genotype frequency expectations suggest that C. arenaria is not predominantly self-fertilized.
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| 2. |
- Cumming, Graeme S., et al.
(författare)
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Network analysis in conservation biogeography : Challenges and opportunities
- 2010
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Ingår i: Diversity & distributions. - : Blackwell Publishing. - 1366-9516 .- 1472-4642. ; 16:3, s. 414-425
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACTAims To highlight the potential value of network analysis for conservation biogeography and to focus attention on some of the challenges that lie ahead in applying it to conservation problems.Location Global.Methods We briefly review existing literature and then focus on five important challenges for the further development of network-based approaches in the field.Results Our five challenges include (i) understanding cross-scale and cross-level linkages in ecological systems (top–down and bottom–up effects, such as trophic cascades, have been demonstrated in food webs but are poorly understood in nested hierarchies such as reserve networks and stream catchments), (ii) capturing dynamic aspects of ecological systems and networks (with a few exceptions we have little grasp of how important whole-network attributes change as the composition of nodes and links changes), (iii) integrating ecological aspects of network theory with metacommunity frameworks and multiple node functions and roles (can we link the spatial patterns of habitat patches in fragmented landscapes, the parallel networks of interacting species using those patches and community-level interactions as defined by metacommunity theory in a single framework?), (iv) integrating the analysis of social and ecological networks (particularly, can they be analysed as a single interacting system?) and (v) laying an empirical foundation for network analysis in conservation biogeography (this will require a larger data bank of well-studied networks from diverse habitats and systems).Main conclusions Recent research has identified a variety of approaches that we expect to contribute to progress in each of our five challenge areas. We anticipate that some of the most exciting outcomes of attempts to meet these challenges will be frameworks that unite areas of research, such as food web analysis and metacommunity theory, that have developed independently.
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| 3. |
- Carruthers, J., et al.
(författare)
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A native at home and abroad : the history, politics, ethics and aesthetics of Acacia
- 2011
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 17:5, s. 810-821
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Tidskriftsartikel (refereegranskat)abstract
- Aim Anthropogenic introductions of Australian Acacia spp. that become classed as alien invasive species have consequences besides the physical, spatial and ecological: there are also cultural, ethical and political considerations that demand attention from scholars in the humanities and social sciences. As practitioners in these disciplines, our aim is to reflect upon some of the social and conceptual ideas and attitudes relating to the spread of Australian Acacia spp. around the world. We therefore provide a longer-term historical and philosophical perspective using South Africa as a key example. We explain some of the cultural aspects of Australian acacias, relating them to history, philosophy and societal ideas that were once, or indeed remain, important, either regarding their exportation from Australia or their importation into other countries. Focussing principally on South Africa and Australia but including brief references to other locations, we augment the literature by making connections between acacia introductions and environmental ethics and aesthetics, national and environmental history and symbolic and other discourses. We evaluate a number of the cultural and philosophical dimensions of invasion biology as a societal response and explicate the interesting contradiction of Australian acacia introductions as simultaneously economically valuable and environmentally transformative in South Africa.
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| 4. |
- Catford, Jane A., et al.
(författare)
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Reducing redundancy in invasion ecology by integrating hypotheses into a single theoretical framework
- 2009
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 15:1, s. 22-40
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Invasion ecology includes many hypotheses. Empirical evidence suggests that most of these can explain the success of some invaders to some degree in some circumstances. If they all are correct, what does this tell us about invasion? We illustrate the major themes in invasion ecology, and provide an overarching framework that helps organize research and foster links among subfields of invasion ecology and ecology more generally.Location: Global.Methods: We review and synthesize 29 leading hypotheses in plant invasion ecology. Structured around propagule pressure (P), abiotic characteristics (A) and biotic characteristics (B), with the additional influence of humans (H) on P, A and B (hereon PAB), we show how these hypotheses fit into one paradigm. P is based on the size and frequency of introductions, A incorporates ecosystem invasibility based on physical conditions, and B includes the characteristics of invading species (invasiveness), the recipient community and their interactions. Having justified the PAB framework, we propose a way in which invasion research could progress.Results: By highlighting the common ground among hypotheses, we show that invasion ecology is encumbered by theoretical redundancy that can be removed through integration. Using both holistic and incremental approaches, we show how the PAB framework can guide research and quantify the relative importance of different invasion mechanisms.Main conclusions: If the prime aim is to identify the main cause of invasion success, we contend that a top-down approach that focuses on PAB maximizes research efficiency. This approach identifies the most influential factors first, and subsequently narrows the number of potential causal mechanisms. By viewing invasion as a multifaceted process that can be partitioned into major drivers and broken down into a series of sequential steps, invasion theory can be rigorously tested, understanding improved and effective weed management techniques identified.
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| 5. |
- Cromsigt, Joris
(författare)
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The difficulty of using species distribution modelling for the conservation of refugee species - the example of European bison
- 2012
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Ingår i: Diversity and Distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 18, s. 1253-1257
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Tidskriftsartikel (refereegranskat)abstract
- Refugee species have been confined to suboptimal habitat through historic anthropogenic factors. If this is unknown, management might actively conserve these species in suboptimal habitat assuming it represents optimal habitat. Similarly, species distribution modelling (SDM) might misguide conservation management of refugee species by only using presence data from suboptimal habitats. We illustrate this by commenting on a recent SDM for European bison that reconstructed the historic distribution of the species. We challenge the interpretation of this model by suggesting an alternative historic biogeography based on the refugee species concept. We argue that, in the case of refugee species, historic reconstructions using SDM cannot be used as a template for conservation management. Rather, experimental re-introduction programmes should provide us with population performance and life history data from a range of suboptimal to optimal habitats. Such data could be used in mechanistic niche modelling to predict potential distribution of refugee species.
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| 6. |
- Dapporto, Leonardo, et al.
(författare)
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Identifying zones of phenetic compression in West Mediterranean butterflies (Satyrinae) : refugia, invasion and hybridization
- 2012
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 18:11, s. 1066-1076
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Tidskriftsartikel (refereegranskat)abstract
- Aim Distinct insular populations are generally considered important units for conservation. In islandmainland situations, unidirectional introgressive gene flow from the most abundant, typically continental, populations into the smaller island populations can erase native insular genetic units. As an indication of threat, the concept of phenetic slope is developed, a measure proportional to differentiation and to geographical proximity. Location The Western Mediterranean, including the following islands: Sardinia, Sicily, Corsica, Balearics, circum-Italian, circum-Sicilian and circum-Sardo-Corsican archipelagos. Eastern Europe is included for comparison. Methods Geometric morphometrics was applied to 2392 male genitalia of seven butterfly species groups. Geographic Information System techniques were used to depict the pattern in the distribution of morphotypes. The slope of variation in genital shape was computed to highlight geographical areas showing abrupt morphological changes. Correlation analyses were performed between the mean slope values across sea straits separating islands and nearest sources and ecological traits of the species that underlie their colonization and migration capacity. Results Phenetic slope analysis has revealed that the strait of Messina and the northern Tyrrhenian Sea support particularly contrasting populations. In these areas, mean slopes for species also correlated with certain ecological traits of the species. Sardinia emerges as the most stable refugium for ancestral mediterranean populations. Main conclusions There is strong support for the hypothesis that Italy has experienced invasion by populations from Eastern Europe with postglacial expansion of these populations across Italy. However, propagules are impeded from invading islands by the expanse of sea straits. Even so, sea straits are not invariably barriers. Our results suggest that wind direction in combination with habitat occupancy may have maintained ancestral insular populations in key locations distinguished by phenetic compression. We conclude that native insular populations acting as barriers to introgression in the areas showing particularly steep phenetic slopes deserve attention in conservation programmes.
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| 7. |
- Dynesius, Mats, et al.
(författare)
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Species richness correlations among primary producers in boreal forests
- 2006
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 12, s. 703-713
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Tidskriftsartikel (refereegranskat)abstract
- Close correlations in species numbers may make it possible to indirectly assess the species richness of difficult taxonomic groups by investigating indicator groups, for which data are more easily collected. We asked if species numbers correlate among the four dominating groups of primary producers in boreal forests (liverworts, macrolichens, mosses, and vascular plants) and if substrate affiliation of species (ground vs. other substrates), sample plot size (0.01-1000 m2), and stand age (young vs. old) influence correlation strength. We used three sets of study plots from northern Sweden each including wide ranges of species richness. Although there are large differences in the ecophysiology and substrate use of vascular plants and the two bryophyte groups (mosses and liverworts), we found strong positive correlations among them not previously reported from boreal forests. In contrast, no correlation in total species richness was found between macrolichens and the two bryophyte groups, despite large overlaps in their ecology. We suggest that the positive correlations among land plants (liverworts, mosses, and vascular plants) are linked to positive relationships between site moisture and species number for all three groups. In contrast, total species number of macrolichens has not been shown to be strongly associated with moisture. However, ground-living lichens and mosses correlated negatively in old forests. This may relate to the inability of macrolichens to exploit shaded and wet old forest ground, a habitat that is used by many moss species. Furthermore, lichens and mosses of 'other substrates' correlated positively in old forests, probably because the amount of boulders was positively related to species richness in both groups. Generally, correlations became stronger with increasing plot size, whereas stand age had relatively little influence. We conclude that vascular plants could be used as an indicator group for species richness of mosses and liverworts in boreal landscapes.
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| 8. |
- Hein, Catherine L, et al.
(författare)
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Dispersal through stream networks : modelling climate-driven range expansions of fishes
- 2011
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 17:4, s. 641-651
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Tidskriftsartikel (refereegranskat)abstract
- Aim To incorporate dispersal through stream networks into models predicting the future distribution of a native, freshwater fish given climate change scenarios. Location Sweden. Methods We used logistic regression to fit climate and habitat data to observed pike (Esox lucius Linnaeus) distributions in 13,476 lakes. We used GIS to map dispersal pathways through streams. Lakes either (1) contained pike or were downstream from pike lakes, (2) were upstream from pike lakes, but downstream from natural dispersal barriers, or (3) were isolated from streams or were upstream from natural dispersal barriers. We then used climate projections to model future distributions of pike and compared our results with and without including dispersal. Results Given climate and habitat, pike were predicted present in all of 99,249 Swedish lakes by 2100. After accounting for dispersal barriers, we only predicted pike presence in 31,538 lakes. Dispersal barriers most strongly limited pike invasion in mountainous regions, but low connectivity also characterized some relatively flat regions. Main conclusions The dendritic network structure of streams and interconnected lakes makes a two-dimensional representation of the landscape unsuitable for predicting range shifts of many freshwater organisms. If dispersal through stream networks is not accounted for, predictions of future fish distributions in a warmer climate might grossly overestimate range expansions of warm and cool-water fishes and underestimate range contractions of cold-water fishes. Dispersal through stream networks can be modelled in any region for which a digital elevation model and species occurrence data are available.
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| 9. |
- Hof, Anouschka R, et al.
(författare)
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How biotic interactions may alter future predictions of species distributions : future threats to the persistence of the arctic fox in Fennoscandia
- 2012
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 18:6, s. 554-562
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Tidskriftsartikel (refereegranskat)abstract
- Aim With climate change, reliable predictions of future species geographic distributions are becoming increasingly important for the design of appropriate conservation measures. Species distribution models (SDMs) are widely used to predict geographic range shifts in response to climate change. However, because species communities are likely to change with the climate, accounting for biotic interactions is imperative. A shortcoming of introducing biotic interactions in SDMs is the assumption that biotic interactions remain the same under changing climatic factors, which is disputable. We explore the performance of SDMs while including biotic interactions.Location Fennoscandia, Europe.Methods We investigate the appropriateness of the inclusion of biotic factors (predator pressure and prey availability) in assessing the future distribution of the arctic fox (Alopex lagopus) in Fennoscandia by means of SDM, using the algorithm MaxEnt.Results Our results show that the inclusion of biotic interactions enhanced the accuracy of SDMs to predict the current arctic fox distribution, and we argue that the accuracy of future predictions might also be enhanced. While the range of the arctic fox is predicted to have decreased by 43% in 2080 because of temperature-related variables, projected increases in predator pressure and reduced prey availability are predicted to constrain the potential future geographic range of the arctic fox in Fennoscandia 13% more.Main conclusions The results indicate that, provided one has a good knowledge of past changes and a clear understanding of interactions in the community involved, the inclusion of biotic interactions in modelling future geographic ranges of species increases the predictive power of such models. This likely has far-reaching impacts upon the design and implementation of possible conservation and management plans. Control of competing predators and supplementary feeding are suggested as necessary management actions to preserve the Fennoscandian arctic fox population in the face of climate change.
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| 10. |
- Marini, Lorenzo, et al.
(författare)
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Traits related to species persistence and dispersal explain changes in plant communities subjected to habitat loss
- 2012
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 18:9, s. 898-908
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Tidskriftsartikel (refereegranskat)abstract
- Aim Habitat fragmentation is a major driver of biodiversity loss but it is insufficiently known how much its effects vary among species with different life-history traits; especially in plant communities, the understanding of the role of traits related to species persistence and dispersal in determining dynamics of species communities in fragmented landscapes is still limited. The primary aim of this study was to test how plant traits related to persistence and dispersal and their interactions modify plant species vulnerability to decreasing habitat area and increasing isolation. Location Five regions distributed over four countries in Central and Northern Europe. Methods Our dataset was composed of primary data from studies on the distribution of plant communities in 300 grassland fragments in five regions. The regional datasets were consolidated by standardizing nomenclature and species life-history traits and by recalculating standardized landscape measures from the original geographical data. We assessed the responses of plant species richness to habitat area, connectivity, plant life-history traits and their interactions using linear mixed models. Results We found that the negative effect of habitat loss on plant species richness was pervasive across different regions, whereas the effect of habitat isolation on species richness was not evident. This area effect was, however, not equal for all the species, and life-history traits related to both species persistence and dispersal modified plant sensitivity to habitat loss, indicating that both landscape and local processes determined large-scale dynamics of plant communities. High competitive ability for light, annual life cycle and animal dispersal emerged as traits enabling species to cope with habitat loss. Main conclusions In highly fragmented rural landscapes in NW Europe, mitigating the spatial isolation of remaining grasslands should be accompanied by restoration measures aimed at improving habitat quality for low competitors, abiotically dispersed and perennial, clonal species.
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