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- Dapporto, Leonardo, et al.
(författare)
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Biogeography of western Mediterranean butterflies : combining turnover and nestedness components of faunal dissimilarity
- 2014
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 41:9, s. 1639-1650
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Tidskriftsartikel (refereegranskat)abstract
- Aim Unpartitioned dissimilarity indices such as the Sorensen index (beta(sor)) tend to categorize areas according to species number. The use of turnover indices, such as the Simpson index (beta(simp)), may lead to the loss of important information represented by the nestedness component (beta(nest)). Recent studies have suggested the importance of integrating nestedness and turnover information. We evaluated this proposition by comparing biogeographical patterns obtained by unpartitioned (beta(sor)) and partitioned indices (beta(simp) and beta(nest)) on presence data of western Mediterranean butterflies. Location Western Mediterranean. Methods We assessed the regionalization of 81 mainland and island faunas according to partitioned and unpartitioned dissimilarity by using cluster analyses with the unweighted pair-group method using arithmetic averages (UPGMA) combined with non-metric multidimensional scaling (NMDS). We also carried out dissimilarity interpolation for beta(sor), beta(simp), beta(nest) and the beta(nest)/beta(sor) ratio, to identify geographical patterns of variation in faunal dissimilarity. Results When the unpartitioned bsor index was used, the clustering of sites allowed a clear distinction between insular and mainland species assemblages. Most islands were grouped together, irrespective of their mainland source, because of the dominant effect of their shared low richness. bsimp was the most effective index for clustering islands with their respective mainland source. bsimp clustered mainland sites into broader regions than clusters obtained using bsor. A comparison of regionalization and interpolation provided complementary information and revealed that, in different regions, the patterns highlighted by bsor could largely be determined either by nestedness or turnover. Main conclusions Partitioned and unpartitioned indices convey complementary information, and are able to reveal the influence of historical and ecological processes in structuring species assemblages. When the effect of nestedness is strong, the exclusive use of turnover indices can generate geographically coherent groupings, but can also result in the loss of important information. Indeed, various factors, such as colonization-extinction events, climatic parameters and the peninsular effect, may determine dissimilarity patterns expressed by the nestedness component.
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| 2. |
- Dapporto, Leonardo, et al.
(författare)
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Comparing population patterns for genetic and morphological markers with uneven sample sizes. An example for the butterfly Maniola jurtina
- 2014
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 5:8, s. 834-843
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Tidskriftsartikel (refereegranskat)abstract
- 1. Integrating genetic and/or phenotypic traits at population level is considered a fundamental approach in the study of evolutionary processes, systematics, biogeography and conservation. But combining the two types of data remain a complex task, mostly due to the high, and sometimes different, sample sizes required for reliable assessments of community traits. Data availability has been increasing in recent years, thanks to online resources, but it is uncommon that different types of markers are available for any given specimen. 2. We provide new R functions aimed at directly correlating traits at population level, even if data sets only overlap partially. The new functions are based on a modified Procrustes algorithm that minimizes differences between bidimensional ordinations of two different markers, based on a subsample of specimens for which both characters are known. To test the new functions, we used a molecular and morphological data set comprising Mediterranean specimens of the butterfly Maniola jurtina. 3. By using this method, we have been able to maximize similarities between genotypic and phenotypic configurations obtained after principal coordinate analysis for the model species and evaluated their degree of correlation at both individual and population level. The new recluster. procrustes function retained the information of the relative importance of different morphological variables in determining the observed ordinations and preserved it in the transformed configurations. This allowed calculating the best combination of morphological variables mirroring genetic relationships among specimens and populations. Finally, it was possible to analyse the modality and variance of the phenotypic characters correlated with the genetic structure among populations. 4. The genetic and phenotypic markers displayed high overall correlation in the study area except in the contact zone, where discrepancies for particular populations were detected. Interestingly, such discrepancies were spatially structured, with southern populations displaying typical western morphotype and eastern haplotypes, while the opposite occurred in the northern populations. The methodology here described can be applied to any number and type of traits for which bidimensional configurations can be obtained, and opens new possibilities for datamining and formeta-analyses combining existing data sets in biogeography, systematics and ecology.
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| 3. |
- 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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| 4. |
- Dennis, Roger L. H., et al.
(författare)
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Butterflies of European islands : the implications of the geography and ecology of rarity and endemicity for conservation
- 2008
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 12:3-4, s. 205-236
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Tidskriftsartikel (refereegranskat)abstract
- Depending on their faunal content islands can function as important ‘vehicles’ for conservation. In this study, we examine data on 440 butterfly species over 564 European islands in 10 island groups. To determine the status of the butterfly fauna, we have adopted two approaches, island-focused and species-focused, examined using principal components analysis and regression modelling.In the former, we relate species richness, rarity and endemicity to island geography (area, elevation, isolation and location in latitude and longitude); in the latter, species occurrence on islands is examined in relation to distribution, range, range boundaries, and altitudinal limits on the continent as well as species’ ecology (number of"/> host plants) and morphology (wing expanse). Species on islands are also assessed for their status on the continental mainland, their distributional dynamics (extinctions, distribution changes) and conservation status (Red Data Book, European Habitat Directive, Species of European Conservation Concern and Bern Convention listing.Unexpectedly, we find that a large fraction of the European butterfly species is found on the islands (63.4%; 59% on small islands) comprising some 6.2% of the land area of Europe. Although species occurring on the islands tend, on the whole, to have lower conservation status and are not declining over Europe, 45 species are endemics restricted to the islands. Species richness shows only a weak locational pattern and is related as expected to isolation from the continental source and island area; but, both rarity and endemicity have distinctive geographical bias to southern Europe, on islands now under increasing pressure from climate change and increasingly intensive human exploitation. The vulnerability of species on islands is emphasised in the relationship of island occurrence (% occurrence and presence/absence of species on any island) with continental distributions. A large proportion of the variation (84%) is accounted by continental distribution, the southern range limit and lower altitudinal limit. Most species (69%) occur on very few islands (\5%). In view of ongoing species dynamics on islands, migrations and extinctions of species, island repositories of species depend in large part on conservation of butterflies at continental sources. The unique faunas and rare species on islands also depend on appropriate concern being given to the island faunas. Conservation of European islands is thus a two-way process, sustaining sources and conserving island refuges. Residuals from the regressions (islands with more or fewer species, rare and endemic species; species occurring more or less frequently than expected on islands) provide warning signals of regions and islands deserving immediate attention.
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| 7. |
- Voda, Raluca, et al.
(författare)
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Cryptic matters : overlooked species generate most butterfly beta-diversity
- 2015
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 38:4, s. 405-409
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Tidskriftsartikel (refereegranskat)abstract
- The cryptic fraction of biodiversity is composed of morphologically similar species that are or have been overlooked by scientists. Although current research is increasingly documenting new cases, cryptic species are frequently ignored in large-scale studies and monitoring programs, either because they have not yet been discovered, or because of the practical difficulties involved in differentiating them. However, it is unknown if this could represent a bias extending beyond the number of missed species. By analyzing the butterfly fauna of the west Mediterranean (335 species), we defined cryptic species based on the current consensus of the scientific community, compared their properties to other congeneric species and investigated the consequences of their inclusion/exclusion in beta-diversity analyses. We show that, as defined, the cryptic fraction of butterfly diversity represents about 25% of the west Mediterranean fauna and is overwhelmingly composed by groups of species that are not sympatric. Our results show that co-occurrence among cryptic species is significantly lower than among congeneric non-cryptic species. Accordingly, albeit the frequency of cryptic species is homogenously distributed over the study area, their distribution pattern accounts for most beta-diversity turnover over sea (from 50 to 100%). Beta-diversity turnover, a direct measure of the frequency of species replacement from site to site, is recognized as a fundamental parameter in ecology and is widely used to detect biogeographic patterns. These findings represent a change of paradigm in showing that cryptic diversity comprises original qualitative aspects in addition to merely quantitative ones. This highlights the importance of differentiating cryptic species for various research fields and opens the door to the study of further potential particularities of cryptic diversity.
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