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Modeling species distributions from heterogeneous data for the biogeographic regionalization of the European bryophyte flora.

Mateo RG, Vanderpoorten A, Muñoz J, Laenen B, Désamoré A - PLoS ONE (2013)

Bottom Line: Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered.The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis.The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany, University of Liège, Liège, Belgium. rubeng.mateo@gmail.com

ABSTRACT
The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered. We produced a biogeographic regionalization of European bryophytes and hypothesized that (1) regions defined for bryophytes would differ from those defined for other taxa due to the highly specific eco-physiology of the group and (2) their high dispersal ability would result in the resolution of few, large regions. Species distributions were recorded using 10,000 km2 MGRS pixels. Because of the lack of data across large portions of the area, species distribution models employing macroclimatic variables as predictors were used to determine the potential composition of empty pixels. K-means clustering analyses of the pixels based on their potential species composition were employed to define biogeographic regions. The optimal number of regions was determined by v-fold cross-validation and Moran's I statistic. The spatial congruence of the regions identified from their potential bryophyte assemblages with large-scale vegetation patterns is at odds with our primary hypothesis. This reinforces the notion that post-glacial migration patterns might have been much more similar in bryophytes and vascular plants than previously thought. The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis. The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular.

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Number of bryophyte species occurrence per MGRS pixel in Europe.when all the data collected (Table S1) are considered (no subsample) and when the most intensively surveyed areas (UK and Germany) are subsampled at 20%, 40% and 60%, respectively.
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pone-0055648-g001: Number of bryophyte species occurrence per MGRS pixel in Europe.when all the data collected (Table S1) are considered (no subsample) and when the most intensively surveyed areas (UK and Germany) are subsampled at 20%, 40% and 60%, respectively.

Mentions: Species distribution models assume that data for each species represent a random sample of their distribution, since otherwise species niches are biased towards climatic conditions that characterize intensively sampled areas [14]. Given the intensity of records in some areas and their scarcity in others in the present data, this condition is clearly not met (Fig. 1). To circumvent this issue, we randomly sub-sampled data for intensively surveyed areas (Germany and the UK), as recommended by Araújo & Guisan [14] and Hijmans and Elith [20]. Four sub-sampling schemes of those areas (no sub-sample, or 60%, 40% and 20% of the data within Germany and the UK) were applied (Fig. 1), and the analyses re-run in each case to allow subsequent comparison of the impact of the sampling intensity. The total number of species with >10 presences in each datamatrix was 1,258 for no sub-sampling strategy, 1,213 for 60% sub-sampling, 1,181 for 40% sub-sampling and 1,151 for 20% sub-sampling. A further 31 species for the full matrix and 46, 36 and 76 species for the matrices sampled at 60%, 40% and 20%, respectively, were removed from the analyses for exhibiting AUC values <0.70.


Modeling species distributions from heterogeneous data for the biogeographic regionalization of the European bryophyte flora.

Mateo RG, Vanderpoorten A, Muñoz J, Laenen B, Désamoré A - PLoS ONE (2013)

Number of bryophyte species occurrence per MGRS pixel in Europe.when all the data collected (Table S1) are considered (no subsample) and when the most intensively surveyed areas (UK and Germany) are subsampled at 20%, 40% and 60%, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569459&req=5

pone-0055648-g001: Number of bryophyte species occurrence per MGRS pixel in Europe.when all the data collected (Table S1) are considered (no subsample) and when the most intensively surveyed areas (UK and Germany) are subsampled at 20%, 40% and 60%, respectively.
Mentions: Species distribution models assume that data for each species represent a random sample of their distribution, since otherwise species niches are biased towards climatic conditions that characterize intensively sampled areas [14]. Given the intensity of records in some areas and their scarcity in others in the present data, this condition is clearly not met (Fig. 1). To circumvent this issue, we randomly sub-sampled data for intensively surveyed areas (Germany and the UK), as recommended by Araújo & Guisan [14] and Hijmans and Elith [20]. Four sub-sampling schemes of those areas (no sub-sample, or 60%, 40% and 20% of the data within Germany and the UK) were applied (Fig. 1), and the analyses re-run in each case to allow subsequent comparison of the impact of the sampling intensity. The total number of species with >10 presences in each datamatrix was 1,258 for no sub-sampling strategy, 1,213 for 60% sub-sampling, 1,181 for 40% sub-sampling and 1,151 for 20% sub-sampling. A further 31 species for the full matrix and 46, 36 and 76 species for the matrices sampled at 60%, 40% and 20%, respectively, were removed from the analyses for exhibiting AUC values <0.70.

Bottom Line: Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered.The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis.The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany, University of Liège, Liège, Belgium. rubeng.mateo@gmail.com

ABSTRACT
The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered. We produced a biogeographic regionalization of European bryophytes and hypothesized that (1) regions defined for bryophytes would differ from those defined for other taxa due to the highly specific eco-physiology of the group and (2) their high dispersal ability would result in the resolution of few, large regions. Species distributions were recorded using 10,000 km2 MGRS pixels. Because of the lack of data across large portions of the area, species distribution models employing macroclimatic variables as predictors were used to determine the potential composition of empty pixels. K-means clustering analyses of the pixels based on their potential species composition were employed to define biogeographic regions. The optimal number of regions was determined by v-fold cross-validation and Moran's I statistic. The spatial congruence of the regions identified from their potential bryophyte assemblages with large-scale vegetation patterns is at odds with our primary hypothesis. This reinforces the notion that post-glacial migration patterns might have been much more similar in bryophytes and vascular plants than previously thought. The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis. The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular.

Show MeSH
Related in: MedlinePlus