星空无限传媒

Parrots are among the most endangered groups of vertebrates on the planet. Admired for their vivid colors and intelligence, they face a deadly combination of habitat loss and relentless illegal trafficking. Of nearly 400 known species, more than 100 are listed as threatened by the International Union for Conservation of Nature (IUCN), with at least half of those endangered species directly impacted by poaching and the wildlife trade.

As conservationists work to save them, they face a fundamental challenge: we still don鈥檛 fully know how many distinct species and subspecies exist鈥攐r where they fit into the parrot family tree. This lack of clarity makes it much harder to track parrot diversity, uncover illegal trade routes, and identify which populations most urgently need protection.

鈥淭o protect parrots effectively, we need a detailed evolutionary map that shows how all these birds are related,鈥� said Dr. Gregory Thom, curator of genetic resources at the LSU Museum of Natural Science (LSU MNS). 鈥淲ithout knowing exactly what we have, it鈥檚 impossible to know what to protect.鈥�

Thom鈥檚 recently awarded $1,157,522 NSF Collaborative Research grant will support the creation of the most comprehensive parrot phylogeny to date. His team will sequence DNA from museum specimens representing nearly every known population of parrots鈥攁bout 800 species and subspecies from around the world.

But unraveling their evolutionary history isn鈥檛 as simple as just sequencing DNA.

A Tangled Tree of Life

Evolutionary trees might look like tidy diagrams where one species splits neatly into two, with branches steadily diverging. In reality, the branches of the tree of life often twist, overlap, and reconnect鈥攂ecause species don鈥檛 always remain completely separate.

鈥淎 big challenge in phylogenetics is that when species exchange genes鈥攚hat we call gene flow鈥攊t complicates our ability to accurately reconstruct phylogenetic trees,鈥� Thom explained.  

Take, for example, the complexity of our own species鈥� evolution: Many people of European descent carry small amounts of Neanderthal DNA鈥攁 relic of ancient interbreeding that happened after modern humans migrated out of Africa around 60,000 years ago.  

That鈥檚 because Neanderthals lived in Europe and western Asia. When modern humans encountered them, they interbred. But people whose ancestors stayed in Africa never met Neanderthals鈥攕o they didn鈥檛 inherit those genes. 

This creates conflicting signals in the human genome. 鈥淪ay you want to draw a family tree of modern human populations and Neanderthals,鈥� Thom said. 鈥淟ooking at the entire genome, all modern humans鈥攔egardless of ancestry鈥攃luster together as one lineage. But if you focus only on the segments inherited from Neanderthals, it can look like Europeans are genetically closer to Neanderthals than to Africans, even though all modern humans belong to the same species.鈥�

鈥淭hat鈥檚 the problem,鈥� he added. 鈥淭he phylogenetic signal can vary a lot across the genome.鈥�  

Parrots are known for hybridizing. When populations become separated鈥攂y rivers, mountains, or other barriers鈥攁nd later reunite, they often interbreed. This flow of genes between populations leaves a complex pattern in their DNA that can obscure true evolutionary relationships.  

With nearly 800 species and subspecies of parrots worldwide, these repeated cycles of separation and mixing have created a tangled evolutionary history. Large-scale genomic datasets add to the complexity: some parts of the genome reflect ancient ancestry, while others capture more recent gene flow between lineages.

To untangle this, Thom and his collaborators will explore parrots鈥� genomic architecture鈥攖he structural and functional organization of the genome and how different regions behave and evolve over time. Not all stretches of DNA tell the same story. Regions on large chromosomes, where recombination occurs less frequently, tend to preserve older evolutionary relationships. In contrast, smaller, fast-recombining chromosomes are more influenced by recent gene exchange.

鈥淲e're building a phylogeny for all taxa of parrots, including species and subspecies, to understand the relationship between genomic architecture and phylogenetic signal,鈥� Thom said. 鈥淎nd by building this phylogeny, hopefully we will solve several problems with the taxonomy of parrots.鈥�

Thom adds that the new parrot phylogeny could guide future research into how complex traits like vocal learning, intelligence, and social behavior evolved. By tracing the genetic and neurobiological roots of these abilities, scientists could gain insights into human cognition and communication.

A Global Collaboration, Rooted in Museum Drawers

The team is combining insights with DNA extracted from museum specimens鈥攕ome dating back to the early 1900s鈥攑rimarily drawn from two major collections: LSU MNS and the American Museum of Natural History (AMNS).

LSU鈥檚 own Museum of Natural Science houses one of the largest collections of Neotropical birds and the third-largest university-based bird collection worldwide, along with one of the oldest and most extensive genetic resources collections globally. Additional specimens come from the AMNS, home to Dr. Brian Smith, curator in the Department of Ornithology and a former LSU MNS postdoctoral researcher, who is a key collaborator on the project.

Together, the two collections provide most of the samples used for the grant, covering nearly the full spectrum of parrot biodiversity, from the Amazon to Australia.

Using refined genomic techniques, they鈥檒l extract and sequence thousands of genetic regions, even from degraded DNA in century-old museum skin specimens. 鈥淲e already have about 90% of the samples we need,鈥� Thom said. 鈥淭he rest we鈥檒l request from collections in South America, Australia, and elsewhere, where we have established collaborations over the years.鈥�

For a select group of parrots, they鈥檒l also sequence entire genomes to better understand how genomic architecture shapes the distribution of evolutionary signal.

The resulting dataset will not only clarify how parrots are related to one another鈥攊t could also correct outdated or inaccurate taxonomic classifications. In the long term, these methods could be applied to other organisms as well.

That alone would be a major contribution to evolutionary biology鈥攂ut Thom鈥檚 team is going further.

From Phylogenies to Forensics

In partnership with the U.S. Fish and Wildlife Service鈥檚 forensic lab in Oregon, the team is working with Dr. Jessica Oswald鈥攁nother former LSU MNS postdoc and currently a senior forensic scientist at USFWS鈥攖o design a set of molecular barcodes based on their new phylogeny. These genetic identifiers will help authorities determine the species or subspecies of confiscated parrots, feathers, or eggs鈥攎aterials often seized from traffickers but difficult to identify. Because many parrot subspecies are found only in specific countries or even on single islands, the tool could also help trace trafficking routes and flag regional trade hotspots.

At its core, the project aims to untangle the parrot family tree鈥攏ot just to understand where parrots came from, but to help protect this fascinating group of birds.