DNA from extinct giant lemurs links archaeolemurids to extant indriids

Abstract

Background: Although today 15% of living primates are endemic to Madagascar, their diversity was even greater in the recent past since dozens of extinct species have been recovered from Holocene excavation sites. Among them were the so-called "giant lemurs" some of which weighed up to 160 kg. Although extensively studied, the phylogenetic relationships between extinct and extant lemurs are still difficult to decipher, mainly due to morphological specializations that reflect ecology more than phylogeny, resulting in rampant homoplasy.

Results: Ancient DNA recovered from subfossils recently supported a sister relationship between giant "sloth" lemurs and extant indriids and helped to revise the phylogenetic position of Megaladapis edwardsi among lemuriformes, but several taxa - such as the Archaeolemuridae - still await analysis. We therefore used ancient DNA technology to address the phylogenetic status of the two archaeolemurid genera (Archaeolemur and Hadropithecus). Despite poor DNA preservation conditions in subtropical environments, we managed to recover 94- to 539-bp sequences for two mitochondrial genes among 5 subfossil samples.

Conclusion: This new sequence information provides evidence for the proximity of Archaeolemur and Hadropithecus to extant indriids, in agreement with earlier assessments of their taxonomic status (Primates, Indrioidea) and in contrast to recent suggestions of a closer relationship to the Lemuridae made on the basis of analyses of dental developmental and postcranial characters. These data provide new insights into the evolution of the locomotor apparatus among lemurids and indriids.

Figure 1

Phylogenetic relationships among lemuriforms. (A) Phylogenetic tree recovered after Bayesian analysis of Dataset #12 using different model parameters for 12S and Cytb genes. Numbers near the nodes refer to posterior probabilities. * Megaladapis haplotype described in Montagnon et al. (2001) [31] (Accession number Genbank:AJ278142), criticized in Karanth et al. (2005) [18] and definitively confirmed here as a probable PCR-contaminant. (B) Summary Consensus of all the phylogenetic trees recovered from the analysis of our 12 datasets.

Figure 2

Model for the evolution indrioids, modified from Godfrey (1988).