Search Results (2)

Litter size plays an essential role in mammalian evolution and is one of the most important factors determining whether an organism is deemed to have a ‘slow’ or ‘fast’ life history strategy. Humans are distinct in being classified as having slow life history yet bearing singletons who have completed relatively less growth than other ape neonates. Previous work has proposed that the ancestral primate gave birth to singletons. However, primate litter size has not yet been contextualized within a broad phylogenetic assessment of mammalian life history. We performed a comprehensive investigation of primate litter size using life history data for 155 primate species, and litter size data for an additional 791 boreoeutherian mammals. Litter size and life history traits have strong phylogenetic signal in primates (Pagel’s lambda: 0.99, p < 0.001; Blomberg’s K: 0.6311. p < 0.001), and litter size is significantly negatively correlated with gestation length (p < 0.001). Our data support that the last common ancestors of both primates and Haplorhini gave birth to multiples (litter size 1.7 and 1.6, respectively). We also find that singleton-bearing pregnancies evolved convergently in multiple primate lineages, including tarsiers and other haplorhines. This study contributes significantly to our understanding of life history and litter size in mammals, and we emphasize the utility of a callitrichid model for investigating the evolution of human reproduction. Full article

Euarchontoglires, once described as Supraprimates, comprise primates, colugos, tree shrews, rodents, and lagomorphs in a clade that evolved about 90 million years ago (mya) from a shared ancestor with Laurasiatheria. The rapid speciation of groups within Euarchontoglires, and the subsequent inherent incomplete marker fixation in ancestral lineages, led to challenged attempts at phylogenetic reconstructions, particularly for the phylogenetic position of tree shrews. To resolve this conundrum, we sampled genome-wide presence/absence patterns of transposed elements (TEs) from all representatives of Euarchontoglires. This specific marker system has the advantage that phylogenetic diagnostic characters can be extracted in a nearly unbiased fashion genome-wide from reference genomes. Their insertions are virtually free of homoplasy. We simultaneously employed two computational tools, the genome presence/absence compiler (GPAC) and 2-n-way, to find a maximum of diagnostic insertions from more than 3 million TE positions. From 361 extracted diagnostic TEs, 132 provide significant support for the current resolution of Primatomorpha (Primates plus Dermoptera), 94 support the union of Euarchonta (Primates, Dermoptera, plus Scandentia), and 135 marker insertion patterns support a variety of alternative phylogenetic scenarios. Thus, whole genome-level analysis and a virtually homoplasy-free marker system offer an opportunity to finally resolve the notorious phylogenetic challenges that nature produces in rapidly diversifying groups. Full article