Primates, consisting of apes, monkeys, tarsiers, and lemurs, are among the most charismatic and well-studied animals on Earth.
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Phylogeny of 455 species of primates synthesized using Chrono-STA. The root of the phylogeny is recovered at 71.3 million years ago. The crown of Strepsirrhini is at 57 million years ago, and the crown of Haplorhini is at 68.5 million years ago. The crown of Simiiformes is at 42.2 million years ago. Image credit: Craig et al., doi: 10.3389/fbinf.2024.1495417.
The mammalian order of Primates comprises 172 species of Old World apes and monkeys (Catarrhini), 146 New World monkeys (Platyrrhini), and 144 lemurs, lorises, and galagos (Strepsirrhini).
Primates exhibit some of the most remarkable behaviors observed in nature; chimpanzees ‘fish’ for termites in hollow logs using specially selected sticks, while orangutans use leaves as gloves to handle spiky durian fruit.
They are some of the most intensely studied species on Earth, and yet there is no comprehensive molecular phylogenetic hypothesis of primate evolutionary history that summarizes the pattern and timing of all primate relationships.
Such a phylogenetic tree would use molecular sequence data to tell us both when each species or group of species first appeared, and which other groups on the tree are their closest relatives.
The largest timed molecular phylogenetic tree of life, called a ‘timetree,’ to date includes just over 200 primate species, while the largest synthetic timetree, drawing from over 4,000 published studies, includes barely double that count, leaving about a fifth of the primate tree of life unresolved.
“The value of timed evolutionary trees containing every species of a given lineage cannot be understated,” said first author Dr. Jack Craig and his colleagues at Temple University.
“While such trees are intrinsically compelling, as they capture the evolutionary history which gave us our present biodiversity, they also form essential foundations for many types of future work.”
“For example, taxonomic and systematic efforts to catalog species rely on them to identify new lineages.”
“Studies of the rate of evolution and its possible correlates like climate and geological changes are fundamentally tied to their underlying phylogenies.”
“Fields like biogeography, phylogeography, and historical ecology, which use timetrees to investigate spatial or ecological patterns, would be impossible without a phylogeny.”
“And, as we watch global biodiversity slip away amid ongoing extinction events, phylogenies are essential tools in identifying conservation priorities and assessing the impacts of our efforts to preserve species.”
In their new research, the authors were able to assemble a timetree of 455 primates, incorporating every species for which molecular data are available
This tree represents the most complete description of the evolutionary relationships among primates to date.
“This effort demonstrated that while the evolutionary history of even some of the most charismatic species on Earth has remained incompletely understood, we have the tools to fill much of this gap in knowledge,” the researchers said.
“We envision our research protocol as an accessible and, ultimately, extremely valuable tool in our efforts to understand evolution.”
“Complete timetrees are a foundational resource in many fields, and we have discovered that they can often be built from existing data.”
“Furthermore, such complete timetrees allow us to test hypotheses we could not otherwise.”
“For example, in the present study, we tested whether the numbers of species in different primate clades could better be explained by unique speciation rates, with some primate lineages generating new species much faster than others, or whether the best explanation was simply time, with all lineages making new species at about the same rate, and older lineages accruing more species over time.”
“What we found was that the major groups of primates did in fact all share relatively similar rates of speciation, and that their age was therefore a better predictor of their species richness.”
“This analysis would be quite problematic if we were missing many species or dates in our timetree, so it serves as a perfect example of the utility of large, complete timetrees.”
The team’s results appear in the journal Frontiers in Bioinformatics.
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Jack M. Craig et al. 2024. Completing a molecular timetree of primates. Frontiers in Bioinformatics 4; doi: 10.3389/fbinf.2024.1495417
