Lineage Diversification and Morphological Evolution in a Large-Scale Continental Radiation: The Neotropical Ovenbirds and Woodcreepers (Aves: Furnariidae)

Abstract

Patterns of diversification in species-rich clades provide insight into the processes that generate biological diversity. We tested different models of lineage and phenotypic diversification in an exceptional continental radiation, the ovenbird family Furnariidae, using the most complete species-level phylogenetic hypothesis produced to date for a major avian clade (97% of 293 species). We found that the Furnariidae exhibit nearly constant rates of lineage accumulation but show evidence of constrained morphological evolution. This pattern of sustained high rates of speciation despite limitations on phenotypic evolution contrasts with the results of most previous studies of evolutionary radiations, which have found a pattern of decelerating diversity-dependent lineage accumulation coupled with decelerating or constrained phenotypic evolution. Our results suggest that lineage accumulation in tropical continental radiations may not be as limited by ecological opportunities as in temperate or island radiations. More studies examining patterns of both lineage and phenotypic diversification are needed to understand the often complex tempo and mode of evolutionary radiations on continents.

Evidence for determinism in species diversification and contingency in phenotypic evolution during adaptive radiation

“…In the snake taxa examined here, morphological diversity is still rising, whereas rates of speciation decline. This has been observed in the fossil record and other molecular phylogenetic studies showing that while rates of morphological and species diversification may be closely tied early in the history of a group, this association becomes unravelled at the end of an AR [7,30,31]. Here, DD reduces speciation rate, but seems to have no effect on rates of morphological change, indicating that different causes change rates of morphological and species diversification.…”

“…However, the pace and process of morphological diversification may have little to do with the pace of species diversification, and may not be predictable across groups that share the same source of EO. Such de-coupling of species diversification and disparification dynamics among groups has been found by other authors [3,11,13,31]. Therefore, morphological change may be contingent to the group, and tied to their particular niches and specific ecological limits under which the clades evolved.…”

“…While this pattern has been detected [29], several studies have demonstrated that early bursts of species diversification may not be associated with early morphological bursts or low within-clade disparification [3,30]. On the other hand, early bursts of morphological diversification can occur without early bursts of species diversification [11,13,31].…”

Species Limits and Clinal Variation in a Widespread High Andean Furnariid: The Buff-breasted Earthcreeper (Upucerthia validirostris)

“…Likewise, U. saturatior was considered a subspecies of U. dumetaria even though it is sister to the albigula + dumetaria clade (Areta andPearman 2009, Derryberry et al 2011). Finally, the genetic distance between the sister taxa jelskii and validirostris is less than half of that between vocally different Upucerthia species (see Derryberry et al 2011 for genetic data and Fig. 5 for vocalizations), which further supports their being conspecific.…”

“…Although U. albigula was confused with U. validirostris [pallida] until its description (Hellmayr 1932), it is more closely related to U. dumetaria than to any other species (Derryberry et al 2011). Likewise, U. saturatior was considered a subspecies of U. dumetaria even though it is sister to the albigula + dumetaria clade (Areta andPearman 2009, Derryberry et al 2011).…”