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An engine for global plant diversity: highest evolutionary turnover and emigration in the American tropics.

Antonelli A, Zizka A, Silvestro D, Scharn R, Cascales-Miñana B, Bacon CD - Front Genet (2015)

Bottom Line: Our results, based on the analysis of c. 22,600 species and c. 20 million geo-referenced occurrence records, show no significant differences between the speciation and extinction of tropical and non-tropical angiosperms.In contrast, the outstanding species richness found today in the American tropics (the Neotropics), as compared to tropical Africa and tropical Asia, is associated with significantly higher speciation and extinction rates.These results imply that the Neotropics have acted as an engine for global plant diversity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Gothenburg Göteborg, Sweden ; Gothenburg Botanical Garden Göteborg, Sweden.

ABSTRACT
Understanding the processes that have generated the latitudinal biodiversity gradient and the continental differences in tropical biodiversity remains a major goal of evolutionary biology. Here we estimate the timing and direction of range shifts of extant flowering plants (angiosperms) between tropical and non-tropical zones, and into and out of the major tropical regions of the world. We then calculate rates of speciation and extinction taking into account incomplete taxonomic sampling. We use a recently published fossil calibrated phylogeny and apply novel bioinformatic tools to code species into user-defined polygons. We reconstruct biogeographic history using stochastic character mapping to compute relative numbers of range shifts in proportion to the number of available lineages through time. Our results, based on the analysis of c. 22,600 species and c. 20 million geo-referenced occurrence records, show no significant differences between the speciation and extinction of tropical and non-tropical angiosperms. This suggests that at least in plants, the latitudinal biodiversity gradient primarily derives from other factors than differential rates of diversification. In contrast, the outstanding species richness found today in the American tropics (the Neotropics), as compared to tropical Africa and tropical Asia, is associated with significantly higher speciation and extinction rates. This suggests an exceedingly rapid evolutionary turnover, i.e., Neotropical species being formed and replaced by one another at unparalleled rates. In addition, tropical America stands out from other continents by having "pumped out" more species than it received through most of the last 66 million years. These results imply that the Neotropics have acted as an engine for global plant diversity.

No MeSH data available.


Number of angiosperm species and occurrences in the four regions defined in this study. The bars show the influence of different cleaning steps on the data set (see also Table 1). (A) Number of species per dataset and geographic region, (B) number of occurrence points per dataset and geographic region, (C) number of species per dataset and geographic region (Tropical vs. Non-Tropical), (D) number of occurrence records per dataset and geographic region (Tropical vs. Non-Tropical). Purple: GBIF download; blue: species that are included (and could be matched) in the phylogeny; dark green: Filter 1 (minimum 3 occurrences to be coded as present in a given region); light green: Filter 2 (additionally 10% of all occurrences per species needed to be coded as present); orange: Filter 3 (additionally widespread species restricted to one region). The Filter 2 data set was used for all analyses except for MuSSE and BaTS.
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Figure 3: Number of angiosperm species and occurrences in the four regions defined in this study. The bars show the influence of different cleaning steps on the data set (see also Table 1). (A) Number of species per dataset and geographic region, (B) number of occurrence points per dataset and geographic region, (C) number of species per dataset and geographic region (Tropical vs. Non-Tropical), (D) number of occurrence records per dataset and geographic region (Tropical vs. Non-Tropical). Purple: GBIF download; blue: species that are included (and could be matched) in the phylogeny; dark green: Filter 1 (minimum 3 occurrences to be coded as present in a given region); light green: Filter 2 (additionally 10% of all occurrences per species needed to be coded as present); orange: Filter 3 (additionally widespread species restricted to one region). The Filter 2 data set was used for all analyses except for MuSSE and BaTS.

Mentions: Figure 3 shows the number of species and occurrences coded into each of the regions defined, the number of those that were also present in the phylogeny, and the influence of each filter applied. The raw data set of species occurrence points (after applying the basic cleaning steps described above) comprised a total of 24,908,478 records pertaining to 188,655 species (purple bars, Figure 3). Many species could not be matched between the species occurrence data set and the molecular phylogeny used, due to taxonomic issues that could not be easily solved (e.g., synonymisation and different taxonomic circumscriptions), and the fact that numerous species did not occur in both data sets. Despite these issues, a total of 27,585 species could be fully matched between the molecular phylogeny and the occurrence data set, representing 14.6% of the total number of currently accepted species of angiosperms (273,174 species, according to http://www.theplantlist.org; accessed September 2014). The data set generated under Filter 2, used for all analyses except MuSSE and BaTS, comprised a total of c. 20 million occurrence points and between c. 500 to 6600 species per region (Figure 3).


An engine for global plant diversity: highest evolutionary turnover and emigration in the American tropics.

Antonelli A, Zizka A, Silvestro D, Scharn R, Cascales-Miñana B, Bacon CD - Front Genet (2015)

Number of angiosperm species and occurrences in the four regions defined in this study. The bars show the influence of different cleaning steps on the data set (see also Table 1). (A) Number of species per dataset and geographic region, (B) number of occurrence points per dataset and geographic region, (C) number of species per dataset and geographic region (Tropical vs. Non-Tropical), (D) number of occurrence records per dataset and geographic region (Tropical vs. Non-Tropical). Purple: GBIF download; blue: species that are included (and could be matched) in the phylogeny; dark green: Filter 1 (minimum 3 occurrences to be coded as present in a given region); light green: Filter 2 (additionally 10% of all occurrences per species needed to be coded as present); orange: Filter 3 (additionally widespread species restricted to one region). The Filter 2 data set was used for all analyses except for MuSSE and BaTS.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4389561&req=5

Figure 3: Number of angiosperm species and occurrences in the four regions defined in this study. The bars show the influence of different cleaning steps on the data set (see also Table 1). (A) Number of species per dataset and geographic region, (B) number of occurrence points per dataset and geographic region, (C) number of species per dataset and geographic region (Tropical vs. Non-Tropical), (D) number of occurrence records per dataset and geographic region (Tropical vs. Non-Tropical). Purple: GBIF download; blue: species that are included (and could be matched) in the phylogeny; dark green: Filter 1 (minimum 3 occurrences to be coded as present in a given region); light green: Filter 2 (additionally 10% of all occurrences per species needed to be coded as present); orange: Filter 3 (additionally widespread species restricted to one region). The Filter 2 data set was used for all analyses except for MuSSE and BaTS.
Mentions: Figure 3 shows the number of species and occurrences coded into each of the regions defined, the number of those that were also present in the phylogeny, and the influence of each filter applied. The raw data set of species occurrence points (after applying the basic cleaning steps described above) comprised a total of 24,908,478 records pertaining to 188,655 species (purple bars, Figure 3). Many species could not be matched between the species occurrence data set and the molecular phylogeny used, due to taxonomic issues that could not be easily solved (e.g., synonymisation and different taxonomic circumscriptions), and the fact that numerous species did not occur in both data sets. Despite these issues, a total of 27,585 species could be fully matched between the molecular phylogeny and the occurrence data set, representing 14.6% of the total number of currently accepted species of angiosperms (273,174 species, according to http://www.theplantlist.org; accessed September 2014). The data set generated under Filter 2, used for all analyses except MuSSE and BaTS, comprised a total of c. 20 million occurrence points and between c. 500 to 6600 species per region (Figure 3).

Bottom Line: Our results, based on the analysis of c. 22,600 species and c. 20 million geo-referenced occurrence records, show no significant differences between the speciation and extinction of tropical and non-tropical angiosperms.In contrast, the outstanding species richness found today in the American tropics (the Neotropics), as compared to tropical Africa and tropical Asia, is associated with significantly higher speciation and extinction rates.These results imply that the Neotropics have acted as an engine for global plant diversity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Gothenburg Göteborg, Sweden ; Gothenburg Botanical Garden Göteborg, Sweden.

ABSTRACT
Understanding the processes that have generated the latitudinal biodiversity gradient and the continental differences in tropical biodiversity remains a major goal of evolutionary biology. Here we estimate the timing and direction of range shifts of extant flowering plants (angiosperms) between tropical and non-tropical zones, and into and out of the major tropical regions of the world. We then calculate rates of speciation and extinction taking into account incomplete taxonomic sampling. We use a recently published fossil calibrated phylogeny and apply novel bioinformatic tools to code species into user-defined polygons. We reconstruct biogeographic history using stochastic character mapping to compute relative numbers of range shifts in proportion to the number of available lineages through time. Our results, based on the analysis of c. 22,600 species and c. 20 million geo-referenced occurrence records, show no significant differences between the speciation and extinction of tropical and non-tropical angiosperms. This suggests that at least in plants, the latitudinal biodiversity gradient primarily derives from other factors than differential rates of diversification. In contrast, the outstanding species richness found today in the American tropics (the Neotropics), as compared to tropical Africa and tropical Asia, is associated with significantly higher speciation and extinction rates. This suggests an exceedingly rapid evolutionary turnover, i.e., Neotropical species being formed and replaced by one another at unparalleled rates. In addition, tropical America stands out from other continents by having "pumped out" more species than it received through most of the last 66 million years. These results imply that the Neotropics have acted as an engine for global plant diversity.

No MeSH data available.