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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.


Results from the range shift analyses using stochastic mapping. The plots show the number of range shift events (including long-distance dispersals and continuous range expansions) through time, relative to the available number of lineages (see Methods for details). (A) Inferred number of range shift events into and out of the tropical zone; (B–D) rate estimations for tropical Africa, Asia, and America, respectively. The 95% confidence intervals are shown as shaded areas in all plots. In (A), a global mean temperature curve (Hansen et al., 2008) is shown in red for comparison. The yellow boxes in the other figures are shown as references for the discussion. EECO, Early Eocene Climatic Optimum; PETM, Paleocene-Eocene Thermal Maximum; GAARlandia, Greater Antilles and Aves Ridge landbridge.
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Figure 5: Results from the range shift analyses using stochastic mapping. The plots show the number of range shift events (including long-distance dispersals and continuous range expansions) through time, relative to the available number of lineages (see Methods for details). (A) Inferred number of range shift events into and out of the tropical zone; (B–D) rate estimations for tropical Africa, Asia, and America, respectively. The 95% confidence intervals are shown as shaded areas in all plots. In (A), a global mean temperature curve (Hansen et al., 2008) is shown in red for comparison. The yellow boxes in the other figures are shown as references for the discussion. EECO, Early Eocene Climatic Optimum; PETM, Paleocene-Eocene Thermal Maximum; GAARlandia, Greater Antilles and Aves Ridge landbridge.

Mentions: The results from the range shift analyses are summarized in Figure 5. Confidence intervals of range shift rates were generally large and mostly overlapping, but the width of their ranges decreased toward the present. During most of the Cenozoic, mean emigration rates (out of the tropics) were slightly higher or very similar to migration into the tropics (Figure 5A). From c. 58 to c. 44 Ma, immigration into the tropics showed a small decrease. Both tropical Africa (Figure 5B) and tropical Asia (Figure 5C) showed similar mean rates of immigration and emigration through time, except for some fluctuations (especially in Asia, prior to c. 25 Ma). In contrast, there was a consistently higher rate of emigration from tropical America (Figure 5D). These rates only reached equilibrium c. 14 Ma.


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)

Results from the range shift analyses using stochastic mapping. The plots show the number of range shift events (including long-distance dispersals and continuous range expansions) through time, relative to the available number of lineages (see Methods for details). (A) Inferred number of range shift events into and out of the tropical zone; (B–D) rate estimations for tropical Africa, Asia, and America, respectively. The 95% confidence intervals are shown as shaded areas in all plots. In (A), a global mean temperature curve (Hansen et al., 2008) is shown in red for comparison. The yellow boxes in the other figures are shown as references for the discussion. EECO, Early Eocene Climatic Optimum; PETM, Paleocene-Eocene Thermal Maximum; GAARlandia, Greater Antilles and Aves Ridge landbridge.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Results from the range shift analyses using stochastic mapping. The plots show the number of range shift events (including long-distance dispersals and continuous range expansions) through time, relative to the available number of lineages (see Methods for details). (A) Inferred number of range shift events into and out of the tropical zone; (B–D) rate estimations for tropical Africa, Asia, and America, respectively. The 95% confidence intervals are shown as shaded areas in all plots. In (A), a global mean temperature curve (Hansen et al., 2008) is shown in red for comparison. The yellow boxes in the other figures are shown as references for the discussion. EECO, Early Eocene Climatic Optimum; PETM, Paleocene-Eocene Thermal Maximum; GAARlandia, Greater Antilles and Aves Ridge landbridge.
Mentions: The results from the range shift analyses are summarized in Figure 5. Confidence intervals of range shift rates were generally large and mostly overlapping, but the width of their ranges decreased toward the present. During most of the Cenozoic, mean emigration rates (out of the tropics) were slightly higher or very similar to migration into the tropics (Figure 5A). From c. 58 to c. 44 Ma, immigration into the tropics showed a small decrease. Both tropical Africa (Figure 5B) and tropical Asia (Figure 5C) showed similar mean rates of immigration and emigration through time, except for some fluctuations (especially in Asia, prior to c. 25 Ma). In contrast, there was a consistently higher rate of emigration from tropical America (Figure 5D). These rates only reached equilibrium c. 14 Ma.

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.