| 1. |
- Aggemyr, Elsa, et al.
(författare)
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Landscape structure and land use history influence changes in island plant composition after 100 years
- 2012
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 39:9, s. 1645-1656
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Tidskriftsartikel (refereegranskat)abstract
- Aim We investigated how current and historical land use and landscape structure affect species richness and the processes of extinction, immigration and species turnover. Location The northern part of the Stockholm archipelago, Baltic Sea, Sweden. We resurveyed 27 islands ranging from 0.3 to 33 ha in area. Methods We compared current plant survey data, cadastral maps and aerial photographs with records obtained from a survey in 1908, using databases and a digital elevation model to examine changes in plant community dynamics in space and time. We examined the effects of local and landscape structure and land use changes on plant species dynamics by using stepwise regression in relation to eight local and three landscape variables. The eight local variables were area, relative age, shape, soil heterogeneity, bedrock ratio, number of houses, forest cover change, and grazing 100 years ago. The three landscape variables were distance to mainland, distance to closest island with a farm 100 years ago, and structural connectivity. Hanskis connectivity measure was modified to incorporate both connectivity and fragmentation. Results The investigated islands have undergone drastic changes, with increasing forest cover, habitation, and abandonment of grassland management. Although the total species richness increased by 31% and mean island area by 23%, we found no significant increase in species richness per unit area. Local variables explain past species richness (100 years ago), whereas both local and landscape variables explain current species richness, extinctions, immigrations and species turnover. Grazing that occurred 100 years ago still influences species richness, even though grazing management was abandoned several decades ago. The evidence clearly shows an increase in nitrophilous plant species, particularly among immigrant species. Main conclusions This study highlights the importance of including land use history when interpreting current patterns of species richness. Furthermore, local environment and landscape patterns affect important ecological processes such as immigration, extinction and species turnover, and hence should be included when assessing the impact of habitat fragmentation and land use change. We suggest that our modified structural connectivity measure can be applied to other types of landscapes to investigate the effects of fragmentation and habitat loss.
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| 2. |
- Ahlgren, Hans, et al.
(författare)
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Multiple prehistoric introductions of the mountain hare (Lepus timidus) on a remote island, as revealed by ancient DNA
- 2016
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 43:9, s. 1786-1796
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The majority of the non-volant mammals now present on the island of Gotland, Sweden, have been introduced in modern times. One exception is the mountain hare (Lepus timidus), which was present on the island more than 9000 years ago. This paper investigates the origins of the Gotland hares and temporal changes in their genetic structure, and considers how they may have reached the island.Location: The island of Gotland, Sweden (57°30′ N, 18°20′ E).Methods: Two fragments of the mitochondrial D-loop 130 + 164 base pairs in length from skeletal remains from 40 ancient mountain hares from Gotland, 38 from the Swedish mainland and five from Lithuania were analysed and compared with 90 modern L. timidus haplotypes from different locations in Eurasia and five haplotypes of the Don-hare (Lepus tanaiticus) morphotype.Results: The Mesolithic hares from Gotland (7304 bc–5989 bc) cluster with modern hares from Russia, Scotland, the Alps and Fennoscandia whereas the Gotland hares from the Neolithic and onwards (2848 bc–1641 ad) cluster with Neolithic hares from the Swedish mainland and modern hares from Fennoscandia. The Neolithic haplotypes from Lithuania and the Don-hare haplotypes were dispersed within the network. The level of differentiation (FST) between the Mesolithic and Neolithic hares on Gotland was twice as great as that observed on the mainland.Main conclusions: The ancient hares on Gotland fall into two haplogroups separated in time, indicating that the mountain hare became extinct at one point, with subsequent re-colonization events. In view of the isolated location of Gotland, it is probable that the hares were brought there by human means of transport.
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| 3. |
- Andersson, Elisabeth, et al.
(författare)
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Plant dispersal in boreal rivers and its relation to the diversity of riparian flora
- 2000
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 27:5, s. 1095-1106
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Tidskriftsartikel (refereegranskat)abstract
- Aim The paper has four major objectives: (1) to determine whether diaspore mimics accurately represent dispersal dynamics of real diaspores in a free-flowing river; (2) to estimate distance travelled and reasons for stranding of floating diaspores along a free-flowing river; (3) to test if species composition and seedling recruitment vary with the ability of the riverbank to trap waterborne drift; and (4) to compare diaspore dispersal in a free-flowing river with that in a regulated river where current velocity has been reduced. Location The field work was conducted in two 7th-order boreal rivers in northern Sweden, the free-flowing Vindel River and the regulated Ume River. Methods We performed a series of dispersal experiments. We tested the usefulness wooden cubes of diaspore mimics for performing dispersal experiments by releasing cubes and achenes of Helianthus annuus and compare their dispersal patterns in the free-flowing Vindel River. We used the cubes to identify 50-m long sections along the river with different trapping capacity, i.e. the number of stranded diaspore mimics within a 50-m section. We then related the number of stranded diaspore mimics to the vascular plant flora, the proportions of species with long or short floating times (i.e. more than or less than 2 days, respectively), the number of seedlings, and to environmental variables within the sections. We also released wooden cubes in a run-of-river impoundment to determine the dispersal capacity of diaspores in a regulated river. Results The cubes were useful as diaspore mimics. They dispersed similarly to achenes of H. annuus. The stranding pattern of diaspore mimics was significantly associated with water current. Species richness of vascular plants per 50-m section increased with the number of stranded mimics. Seedling recruitment, and the proportions of species with short-floating and long-floating diaspores, did not vary with the number of stranded mimics. The ability of a river to transport diaspores downstream was strongly reduced by impoundment. Main conclusions We conclude that patterns of species richness of riparian vegetation is in part determined by the ability of the riverbank to trap waterborne diaspores, but differences in floating ability among species did not affect the species composition along free-flowing rivers.
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| 4. |
- Appelhans, Marc S., et al.
(författare)
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Age and historical biogeography of the pantropically distributed Spathelioideae (Rutaceae, Sapindales)
- 2012
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 39:7, s. 1235-1250
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Tidskriftsartikel (refereegranskat)abstract
- Aim The family Rutaceae (rue family) is the largest within the eudicot order Sapindales and is distributed mainly in the tropical and subtropical regions of both the New World and the Old World, with a few genera in temperate zones. The main objective of this study is to present molecular dating and biogeographical analyses of the subfamily Spathelioideae, the earliest branching clade (which includes eight extant genera), to interpret the temporal and spatial origins of this group, ascertaining possible vicariant patterns and dispersal routes and inferring diversification rates through time. Location Pantropics. Methods A dataset comprising a complete taxon sampling at generic level (83.3% at species level) of Spathelioideae was used for a Bayesian molecular dating analysis (beast). Four fossil calibration points and an age constraint for Sapindales were applied. An ancestral area reconstruction analysis utilizing the dispersalextinctioncladogenesis model and diversification rate analyses was conducted. Results Dating analyses indicate that Rutaceae and Spathelioideae are probably of Late Cretaceous origin, after which Spathelioideae split into a Neotropical and a Palaeotropical lineage. The Palaeotropical taxa have their origin inferred in Africa, with postulated dispersal events to the Mediterranean, the Canary Islands, Madagascar and Southeast Asia. The lineages within Spathelioideae evolved at a relatively constant diversification rate. However, abrupt changes in diversification rates are inferred from the beginning of the Miocene and during the Pliocene/Pleistocene. Main conclusions The geographical origin of Spathelioideae probably lies in Africa. The existence of a Neotropical lineage may be the result of a dispersal event at a time in the Late Cretaceous when South America and Africa were still quite close to each other (assuming that our age estimates are close to the actual ages), or by Gondwanan vicariance (assuming that our age estimates provide minimal ages only). Separation of land masses caused by sea level changes during the Pliocene and Pleistocene may have been triggers for speciation in the Caribbean genus Spathelia.
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| 5. |
- Arnell, Matilda, et al.
(författare)
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Landscape-scale range filling and dispersal limitation of woody plants
- 2022
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 49:11, s. 2028-2036
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The extent to which species fill their predicted current ranges and the underlying process of dispersal limitation have implications for species' abilities to track climate change. Range filling is intimately related to spatial scale, yet range filling estimates at high resolutions are largely lacking. In this study, we aim to estimate range filling and dispersal limitation at a high resolution for woody plants with different dispersal systems and habitat affinities.Location: Sweden.Taxon: All genera of woody plants (trees and shrubs).Methods: We estimated landscape-scale range filling for 64 species. Two main dispersal systems, vertebrate dispersal and abiotic dispersal, occurred among these species. Range filling was estimated as the realized range divided by the potential range, that is, the occupied proportion of a species' modelled range, at a 1 km2 resolution. We estimated potential ranges using species distribution models and realized ranges from presence records. To increase the likelihood that absences represented true absences the estimations were restricted to areas with high sampling effort. We tested the effects of dispersal system on range filling, controlling for species' habitat affinities.Results: Vertebrate-dispersed woody species had significantly lower landscape-scale range filling than species with abiotic dispersal. Range filling was also linked to habitat affinity. Species associated with intermediate levels of light and moisture had the highest range filling estimates.Main conclusions: Landscape-scale range filling of woody species is linked to their dispersal traits. When controlling for habitat affinity, our result suggests that dispersal limitation partly explains the lower occupancy in suitable habitat found for vertebrate-dispersed plants. Given that vertebrate-dispersed species fail to reach suitable habitats at this scale, they are less likely to track changes in climate than woody plants with abiotic dispersal.
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| 6. |
- Aronsson, Heléne, 1994, et al.
(författare)
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Expert-based range maps cannot be replicated using data-driven methods but macroecological conclusions arising from them can
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699.
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Tidskriftsartikel (refereegranskat)abstract
- AimAnswering many fundamental and applied scientific questions relies on accurate geographic range maps for species, such as those compiled by experts working with the International Union for Conservation of Nature (IUCN). However, these maps are resource demanding to produce and only available for a limited number of organisms. Here, we test to what extent standardized, data-driven methods based on publicly available occurrences can reproduce expert-based IUCN range maps and the macroecological conclusions drawn from them.LocationGlobal.Time PeriodPresent.TaxaBirds.Materials and MethodsWe estimated the geographic ranges for 7385 non-marine bird species which either were non-migratory or had spatially connected breeding and wintering ranges from publicly available, georeferenced point occurrences. We then quantified the spatial overlap between these range estimates and the IUCN expert-derived range estimates. Finally, we compared global species richness patterns and the environmental correlates that emerge from both approaches.ResultsWe find that range estimates based on point occurrence records overlap on average 52% with expert range estimates for the same species. The global species richness patterns estimated under both approaches are overall similar but show local and regional differences, for example, in the tropical Andes of northern South America and the Central Arc region of Africa. The estimated global drivers of richness are similar.Main ConclusionsExpert-derived estimates of species distributions are not reproducible by data-driven approaches relying on currently available public records, even for well-documented taxa such as birds. However, these discrepancies do not substantially change our macroecological understanding of global drivers of bird diversity.
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| 7. |
- Astor, Tina, et al.
(författare)
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Importance of environmental and spatial components for species and trait composition in terrestrial snail communities
- 2017
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 44, s. 1362-1372
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Tidskriftsartikel (refereegranskat)abstract
- AimDespite the huge diversity of soil animals and their recognized contribution to many ecosystem functions, little is known about the relative importance of factors controlling their abundance and distribution. We examined the relative importance of environmental and spatial factors in explaining the species and functional trait composition of terrestrial snail communities at the level of meta-communities (spatial extent c.100x100km) in a heterogeneous, intensively used landscape. We hypothesized that both spatial and environmental factors contribute to the variation in community structure across the landscape, but expected environmental variables describing local habitat conditions to be most important.LocationCounty of Skane, south Sweden.MethodsWe quantified community structure in terms of species composition and as functional trait composition, because functional traits directly link species performance to environmental conditions. To disentangle the unique and shared contribution of environmental and spatial factors to the variation in snail community structure (in terms of species and trait composition) we applied a partial redundancy analysis.ResultsSpecies traits explained more of the variance in community composition than species identity. Snail traits such as tolerance to environmental stress (related to soil moisture content) and niche width were correlated with the main environmental gradient. Environmental variables (i.e. soil moisture content, vegetation characteristics and soil pH) contributed considerably more to variation in community composition (species: 11.4%; traits: 24.9%) than the spatial variables (species: 6.5%; traits: 4.2%).Main conclusionsThe results highlight that both environmental and spatial variables are required to understand the relative importance of niche-based and intrinsic population processes as drivers of terrestrial snail community structure. However, at the scale of our study niche-based community structuring explained by the trait-environment relationship is considerably more important than spatial patterning independent of the environment.
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| 8. |
- Audusseau, Hélène, et al.
(författare)
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Species range expansion constrains the ecological niches of resident butterflies
- 2017
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 44:1, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Changes in community composition resulting from environmental changes modify biotic interactions and affect the distribution and density of local populations. Such changes are currently occurring in nettle-feeding butterflies in Sweden where Araschnia levana has recently expanded its range northward and is now likely to interact with resident species (Aglais urticae and Aglais io). Butterfly occurrence data collected over years and across regions enabled us to investigate how a recent range expansion of A. levana may have affected the environmental niche of resident species.Location: We focused on two regions of Sweden (Skane and Norrstrom) where A. levana has and has not established and two time periods (2001-2006 and 2009-2012) during its establishment in Skane.Methods: We performed two distinct analyses in each region using the PCA-env and the framework described in Broennimann etal. (2012). First, we described the main sources of variation in the environment. Second, in each time period and region, we characterized the realized niches of our focal species across topographic and land use gradients. Third, we quantified overlaps and differences in realized niches between and within species over time.Results: In Skane, A. levana has stabilized its distribution over time, while the distribution of the native species has shifted. These shifts depicted a consistent pattern of avoiding overlap between the native species and the environmental space occupied by A. levana, and it was stronger for A. urticae than for A. io. In both regions, we also found evidence of niche partitioning between native species.Main conclusions: Interspecific interactions are likely to affect local species distributions. It appears that the ongoing establishment of A. levana has modified local biotic interactions and induced shifts in resident species distributions. Among the mechanisms that can explain such patterns of niche partitioning, parasitoid-driven apparent competition may play an important role in this community.
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| 9. |
- Azevedo, Josué, et al.
(författare)
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Contrasting patterns of phylogenetic turnover in amphibians and reptiles are driven by environment and geography in Neotropical savannas
- 2021
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 48:8, s. 2008-2021
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Cross-taxonomic congruence in biodiversity patterns is key to understanding the main drivers of community structure, for biogeographical regionalization and to guide conservation. We aim to map the patterns of phylogenetic turnover and disentangle the geographical and environmental factors that drive the phylogenetic composition of distinct faunal assemblages. Location: The Cerrado savannas of South America. Taxa: Reptiles and amphibians. Methods: We measured the proportion of phylogenetic branches shared among sites (i.e. phylogenetic turnover) using presence-absence matrices for all species in the Cerrado and for endemics only, including only well-sampled localities from previously compiled inventories. We then tested whether phylogenetic turnover is different from null expectations based on taxonomic turnover. We used generalized dissimilarity modelling (GDM) to test whether geography, topography, soil or climate best explain phylogenetic turnover. Finally, we mapped the observed and the GDM-predicted clustering of phylogenetic turnover to assess geographical congruence between reptiles and amphibians. Results: For all reptiles, geographical distance is the most important factor explaining phylogenetic turnover, whereas for endemic reptiles and amphibians, in general, a set of climatic variables and relief roughness are more important. We did not find any significant correlation between the phylogenetic turnover of reptiles and amphibians, as evidenced by non-congruent phylogenetic clustering and by different responses to geographical and environmental gradients. Main conclusions: The different relationships of phylogenetic turnover of reptiles and amphibians to geographical and environmental distances have ultimately shaped the phylogenetic regionalization of these two groups. This incongruence indicates the differential importance of niche filtering, dispersal limitation and the influence of neighbouring biomes in the regionalization of different groups of organisms. Therefore, diversity patterns of one group should ideally not be used as a surrogate to map general patterns or to understand the drivers of diversity of other co-occurring groups. Thus, conservation efforts need to be designed and implemented for each organismal group. © 2021 John Wiley & Sons Ltd
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| 10. |
- Backéus, Ingvar
(författare)
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Ecotone versus ecocline: vegetation zonation and dynamics around a small reservoir in Tanzania
- 1993
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Ingår i: Journal of Biogeography. - 0305-0270 .- 1365-2699. ; 20, s. 209-218
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Tidskriftsartikel (refereegranskat)abstract
- Data from transects on the shores and drawdown area of a small reservoir in Tanzania with a strongly fluctuating water level were used to illuminate a spatial and shortterm temporalvariation in the vegetation of a borderzone. Vegetation data were related to the position of the sample plots in relation to a water level gauge and to time (seasonal changes and changes between two consecutive years).Few perennial species survived the rainy season in the zone exposed to the fluctuating water level. Most plants were annuals that colonized yearly. The vegetation under the full supply level (=FSL) was sparse and related to Eriochloetum nubicae and Ecliption albae. An observed great variation between sites and years of this kind of vegetation seems to be due to the unstable character of the sites with frequent recolonization of bare land.The need to distinguish formally between ecotones (in a strict sense) and ecoclines is stressed. The drawdown area has (a) a peak in β diversity just below FSL, (b) no β diversity in a zone below FSL that was not flooded the preceding rainy season and (c) a certain amount of β diversity further down.(a) and(b) are considered typical of an ecotone. (c) is interpreted as a 'shortterm ecocline' of colonizing annuals between two rainy seasons. The system belowFSL as a whole is an ecotone. The shore above FSL is an ecocline with high α and β diversity.A downward movement of plant species during the dry season is demonstrated using canonical correspondence analysis. Thus, this ecotone is driven by the environment and no internal (autonomous) control is likely to occur
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