The evolution of tinamous (Palaeognathae: Tinamidae) in light of molecular and combined analyses

Abstract

The Neotropical tinamous are of particular interest in our efforts to understand the evolution of modern birds. They inhabit both forested and open environments and, although volant, have limited flight capabilities. Numerous studies have recognized the monophyly of tinamous and their relationships either as sister to the flightless ratites (ostriches, emus and their relatives) or within the ratites themselves. Despite the numerous bird phylogenies published recently, modern investigations of relationships within the tinamous themselves have been limited. Here, we present the first detailed phylogenetic analysis and divergence-date estimation including a significant number of tinamou species, both extant and fossil. The monophyly of most currently recognized polytypic genera is recovered with high support, with the exception of the paraphyletic Nothura and Nothoprocta. The traditional subdivision between those tinamous inhabiting open areas (Nothurinae) and forest environments (Tinaminae) is also confirmed. A temporal calibration of the resultant phylogeny estimates that the basal divergence of crown Tinamidae took place between 31 and 40 Mya.

The Evolution and Fossil Record of Palaeognathous Birds (Neornithes: Palaeognathae)

“…When characters were unweighted in the maximum parsimony analysis but constrained to a molecular backbone, a monophyletic Lithornithidae was once again sister to Tinamidae [137]. Almeida, et al [42] also recovered lithornithids as sister to crown Palaeognathae in their Bayesian topology, but sister to tinamous in their maximum parsimony and maximum likelihood trees. Maximum likelihood trees inferred using characters exhibiting low homoplasy also supported a position on the palaeognath stem for Lithornithidae [49], though the monophyly of the clade was dependent on the matrix used.…”

“…However, over the past twenty years, molecular phylogenetic analyses have forced a wholescale revision of the Gondwanan vicariance paradigm of palaeognath evolution and historical biogeography. Evidence from analyses of both nuclear [35][36][37][38][39][40][41][42][43] and mitochondrial DNA [41,42,[44][45][46], as well as large-scale phylogenomic analyses [47][48][49][50], demonstrate that tinamids are in fact phylogenetically nested within ratites, rendering "Ratitae" paraphyletic, once again reviving the early hypothesis of ratite non-monophyly [4,[20][21][22][23][24] (Figure 5). (a) Ratite monophyly based on the morphological study of Livezey and Zusi [30].…”

“…(a) Ratite monophyly based on the morphological study of Livezey and Zusi [30]. (b) Molecular phylogeny suggesting ratite paraphyly recovered by Mitchell, et al [45], Grealy, et al [41], Yonezawa, et al [49], Urantówka, et al [46], and Almeida, et al [42].…”

“…The recent revival of a phylogenetic hypothesis stipulating that ratites repeatedly and independently lost the capacity to fly has largely been driven by molecular phylogenetic analyses [36][37][38][39][40][41][42][43][44][45][46][48][49][50][54][55][56][57][58], but has accrued supporting evidence from independent datasets. For instance, embryological studies have demonstrated important differences in patterns of wing growth among ostriches and emu, suggesting that alternative heterochronic mechanisms may underlie the acquisition of flightlessness in disparate ratite taxa and potentially supporting independent evolutionary transitions to flightlessness among ratites [59].…”

“…The recognition of ratite paraphyly, coupled with phylogenomic time trees that indicate an origin of crown palaeognaths long after the breakup of Gondwana commenced (e.g., [41,42,45,48,49,55]), makes the classic vicariance hypothesis untenable. Instead, present-day palaeognath biogeography must be the product of dispersal of volant ancestral palaeognaths to multiple landmasses preceding independent origins of flightlessness (Figure 6).…”