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Large ‐ scale dark diversity estimates: new perspectives with combined methods

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ABSTRACT

Large‐scale biodiversity studies can be more informative if observed diversity in a study site is accompanied by dark diversity, the set of absent although ecologically suitable species. Dark diversity methodology is still being developed and a comparison of different approaches is needed. We used plant data at two different scales (European and seven large regions) and compared dark diversity estimates from two mathematical methods: species co‐occurrence (SCO) and species distribution modeling (SDM). We used plant distribution data from the Atlas Florae Europaeae (50 × 50 km grid cells) and seven different European regions (10 × 10 km grid cells). Dark diversity was estimated by SCO and SDM for both datasets. We examined the relationship between the dark diversity sizes (type II regression) and the overlap in species composition (overlap coefficient). We tested the overlap probability according to the hypergeometric distribution. We combined the estimates of the two methods to determine consensus dark diversity and composite dark diversity. We tested whether dark diversity and completeness of site diversity (log ratio of observed and dark diversity) are related to various natural and anthropogenic factors differently than simple observed diversity. Both methods provided similar dark diversity sizes and distribution patterns; dark diversity is greater in southern Europe. The regression line, however, deviated from a 1:1 relationship. The species composition overlap of two methods was about 75%, which is much greater than expected by chance. Both consensus and composite dark diversity estimates showed similar distribution patterns. Both dark diversity and completeness measures exhibit relationships to natural and anthropogenic factors different than those exhibited by observed richness. In summary, dark diversity revealed new biodiversity patterns which were not evident when only observed diversity was examined. A new perspective in dark diversity studies can incorporate a combination of methods.

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Completeness of site diversity at the regional scale calculated with (A) species co‐occurrence and (B) species distribution modeling method, and (C) consensus of used methods and (D) composite of used methods. For comparison, we used the same scale for all maps. Projection: Lambert azimuthal equal area.
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ece32371-fig-0005: Completeness of site diversity at the regional scale calculated with (A) species co‐occurrence and (B) species distribution modeling method, and (C) consensus of used methods and (D) composite of used methods. For comparison, we used the same scale for all maps. Projection: Lambert azimuthal equal area.

Mentions: Both SCO and SDM methods resulted in similar scattered patterns of completeness of site diversity across Europe (Fig. 4). Relatively complete sites can be found in both in north and south Europe. Estimates of completeness of site diversities increased with increasing heterogeneity (PCA1); the trend, however, was significantly weaker compared with the positive relationship between heterogeneity and observed species richness (Table 1). In general, completeness estimates were not significantly different from observed species richness results, which showed no strong relationship with latitude (PCA2). There were positive relationships with seasonality (PCA3), similar to the relationship with species richness (Table 1). At the regional scale, SCO and SDM methods show in general concordant patterns with some differences, for example, sites appear more complete by SDM than by SCO in some regions in Germany and Ireland (Fig. 5). Different estimates of completeness of site diversities decreased with increasing latitude (PCA1), but the relationships were generally not stronger for observed species richness (except for SCO completeness, Table 2). All estimates of completeness of site diversities showed positive relationship with heterogeneity (PCA2), which was significantly different than that of observed species richness (negative relationship).


Large ‐ scale dark diversity estimates: new perspectives with combined methods
Completeness of site diversity at the regional scale calculated with (A) species co‐occurrence and (B) species distribution modeling method, and (C) consensus of used methods and (D) composite of used methods. For comparison, we used the same scale for all maps. Projection: Lambert azimuthal equal area.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016647&req=5

ece32371-fig-0005: Completeness of site diversity at the regional scale calculated with (A) species co‐occurrence and (B) species distribution modeling method, and (C) consensus of used methods and (D) composite of used methods. For comparison, we used the same scale for all maps. Projection: Lambert azimuthal equal area.
Mentions: Both SCO and SDM methods resulted in similar scattered patterns of completeness of site diversity across Europe (Fig. 4). Relatively complete sites can be found in both in north and south Europe. Estimates of completeness of site diversities increased with increasing heterogeneity (PCA1); the trend, however, was significantly weaker compared with the positive relationship between heterogeneity and observed species richness (Table 1). In general, completeness estimates were not significantly different from observed species richness results, which showed no strong relationship with latitude (PCA2). There were positive relationships with seasonality (PCA3), similar to the relationship with species richness (Table 1). At the regional scale, SCO and SDM methods show in general concordant patterns with some differences, for example, sites appear more complete by SDM than by SCO in some regions in Germany and Ireland (Fig. 5). Different estimates of completeness of site diversities decreased with increasing latitude (PCA1), but the relationships were generally not stronger for observed species richness (except for SCO completeness, Table 2). All estimates of completeness of site diversities showed positive relationship with heterogeneity (PCA2), which was significantly different than that of observed species richness (negative relationship).

View Article: PubMed Central - PubMed

ABSTRACT

Large‐scale biodiversity studies can be more informative if observed diversity in a study site is accompanied by dark diversity, the set of absent although ecologically suitable species. Dark diversity methodology is still being developed and a comparison of different approaches is needed. We used plant data at two different scales (European and seven large regions) and compared dark diversity estimates from two mathematical methods: species co‐occurrence (SCO) and species distribution modeling (SDM). We used plant distribution data from the Atlas Florae Europaeae (50 × 50 km grid cells) and seven different European regions (10 × 10 km grid cells). Dark diversity was estimated by SCO and SDM for both datasets. We examined the relationship between the dark diversity sizes (type II regression) and the overlap in species composition (overlap coefficient). We tested the overlap probability according to the hypergeometric distribution. We combined the estimates of the two methods to determine consensus dark diversity and composite dark diversity. We tested whether dark diversity and completeness of site diversity (log ratio of observed and dark diversity) are related to various natural and anthropogenic factors differently than simple observed diversity. Both methods provided similar dark diversity sizes and distribution patterns; dark diversity is greater in southern Europe. The regression line, however, deviated from a 1:1 relationship. The species composition overlap of two methods was about 75%, which is much greater than expected by chance. Both consensus and composite dark diversity estimates showed similar distribution patterns. Both dark diversity and completeness measures exhibit relationships to natural and anthropogenic factors different than those exhibited by observed richness. In summary, dark diversity revealed new biodiversity patterns which were not evident when only observed diversity was examined. A new perspective in dark diversity studies can incorporate a combination of methods.

No MeSH data available.


Related in: MedlinePlus