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EXPLOSIVE EVOLUTIONARY RADIATIONS: DECREASING SPECIATION OR INCREASING EXTINCTION THROUGH TIME?
Author(s) -
Rabosky Daniel L.,
Lovette Irby J.
Publication year - 2008
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.2008.00409.x
Subject(s) - genetic algorithm , extinction (optical mineralogy) , biology , extinction event , explosive material , diversification (marketing strategy) , evolutionary biology , macroevolution , lineage (genetic) , ecology , phylogenetics , paleontology , gene , demography , population , genetics , biological dispersal , marketing , sociology , business , chemistry , organic chemistry
A common pattern in time‐calibrated molecular phylogenies is a signal of rapid diversification early in the history of a radiation. Because the net rate of diversification is the difference between speciation and extinction rates, such “explosive‐early” diversification could result either from temporally declining speciation rates or from increasing extinction rates through time. Distinguishing between these alternatives is challenging but important, because these processes likely result from different ecological drivers of diversification. Here we develop a method for estimating speciation and extinction rates that vary continuously through time. By applying this approach to real phylogenies with explosive‐early diversification and by modeling features of lineage‐accumulation curves under both declining speciation and increasing extinction scenarios, we show that a signal of explosive‐early diversification in phylogenies of extant taxa cannot result from increasing extinction and can only be explained by temporally declining speciation rates. Moreover, whenever extinction rates are high, “explosive early” patterns become unobservable, because high extinction quickly erases the signature of even large declines in speciation rates. Although extinction may obscure patterns of evolutionary diversification, these results show that decreasing speciation is often distinguishable from increasing extinction in the numerous molecular phylogenies of radiations that retain a preponderance of early lineages.