Convergence and divergence in the evolution of aquatic birds

Abstract

Aquatic birds exceed other terrestrial vertebrates in the diversity of their adaptations to aquatic niches. For many species this has created di¤culty in understanding their evolutionary origin and, in particular, for the £amingos, hamerkop, shoebill and pelecaniforms. Here, new evidence from nuclear and mitochondrial DNA sequences and DNA^DNA hybridization data indicates extensive morphological convergence and divergence in aquatic birds. Among the unexpected ¢ndings is a grouping of £amingos and grebes, species which otherwise show no resemblance. These results suggest that the traditional characters used to unite certain aquatic groups, such as totipalmate feet, foot-propelled diving and long legs, evolved more than once and that organismal change in aquatic birds has proceeded at a faster pace than previously recognized.

Reinterpreting the origins of flamingo lice: cospeciation or host-switching?

“…Molecular and morphological data both suggest that flamingos are actually closely related to grebes (Podocipediformes; Van Tuinen et al 2001;Mayr 2004). Other recent molecular studies have also supported this relationship ( Johnson 2001 (not shown);Chubb 2004).…”

“…Avian feather lice (Ischnocera) are particularly diverse among lice, and while phylogenetic information for many groups of birds is becoming more readily available, the phylogeny of avian Ischnocera is still poorly understood, although progress is being made on some groups (Cruickshank et al 2001;Johnson et al 2003). In addition, the higher level phylogenetic relationships of birds is still relatively poorly known, although this lack of knowledge is also changing ( Johnson 2001;Van Tuinen et al 2001;Chubb 2004). Thus, until recently, it has been difficult to interpret the history of higher level bird-louse associations.…”

“…Bayesian posterior probabilities were calculated by discarding the first 300 000 generations as burn-in from a 10 million generation Markov Chain Monte Carlo (MCMC) chain, and calculating a 50% majority consensus tree of the remaining trees sampled every 1000 generations. Trees were rooted on a composite outgroup of various genera of avian and mammalian Ischnocera, focusing on lice from waterbirds present in the phylogeny of Van Tuinen et al (2001).…”

“…Thus, we used simplified phylogenies for the relevant groups of birds and their lice. For the avian phylogeny, we used a composite of the phylogeny presented by Van Tuinen et al (2001) based on DNA-DNA hybridization and nuclear DNA sequences. This phylogeny included the sister relationship between flamingos and grebes, which is strongly supported in the Van Tuinen et al (2001) study.…”

“…cospeciation) or is a result of host switching. For this analysis, we use the relevant taxa from higher level phylogenies of waterbirds (Van Tuinen et al 2001) and their lice (Smith et al 2004). We also provide new data and analyses to evaluate whether the Anaticola of flamingos are indeed closely related to those of ducks, because previous studies of avian louse phylogenies did not include this genus from flamingos.…”