Abstract Detail

Macroevolution

Beaulieu, Jeremy [1], O'Meara, Brian [2], Caetano , Daniel S [3].

Testing for geography-dependent rates of species turnover in campanulid angiosperms.

The spatial distribution of flowering plant species varies considerably, with species diversity declining as one moves from the equator out towards the poles. This latitudinal gradient in species richness is correlated with estimates of diversification rates. The tropical biomes at lower latitudes exhibit generally higher diversification rates than the more seasonal environments of the temperate biomes at higher latitudes. The relative paucity of clades that have succeeded in temperate regions suggests that temperate clades are the result of successful dispersion events out of the tropics. However, the Campanulidae is a large flowering plant clade that exhibits the opposite pattern. Despite a few speciose clades largely confined to the tropical regions of the Southern Hemisphere, the large majority of extant species richness of campanulids can be found in the temperate regions of the Northern Hemisphere. Here, we apply a powerful new approach that estimates turnover (i.e., speciation+extinction), extinction fraction (i.e., extinction/speciation), and dispersal rates associated with tropical and temperate lineages. Specifically, we test whether the apparent success of campanulids in the temperate biomes is a recent event, explained by an increase in turnover rates, because increases in the rate with which lineages are generated and get extinct can stochastically lead to a sudden build up in species richness. However, such events are unlikely to be stable over time and might suggest that campanulids are not, in fact, an exception to the rule. For this, we evaluate a large set of biologically plausible models in hiGeoSSE that jointly estimate the effect of geographic range, as well as other drivers, on diversification while also taking into account the natural heterogeneity in rates observed in plant phylogenies. Here we also expand these models in order to include more complex histories, such as the interplay between geographical distribution, dispersal syndrome and growth habit with respect to changes in diversification rates across the branches of the tree. Finally, we test the robustness of our results to the various ways in which tropical versus temperate regions are often delimited.

1 - University of Arkansas, Biological Sciences, 601 Science and Engineering, Fayetteville, AR, 72702, USA
2 - 8424 Mecklenburg Ct., Knoxville, TN, 37923, United States
3 - University of Arkansas, Department of Biological Sciences, SCEN Room 735, Fayetteville, AR, 72703, US

Keywords:
Biogeography
diversification
Tropical plants
temperate plants
campanulids.

Presentation Type: Oral Paper
Session: 42, Macroevolution II
Location: 107/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 2:45 PM
Number: 42006
Abstract ID:946
Candidate for Awards:None