Lizards and snakes are in the biological group Squamata, which is very interesting and has the attention of both scientists and animal fans. As a herpetology fan, Squamata is my favorite taxon because it has many species, critical ecological roles, and unique genetic traits. We know much more about how Squamata changed over the years thanks to better molecular methods and the ongoing review of phylogenetic studies. Once upon a time, Squamata were grouped by their forms, such as whether they had legs, their skulls, and how their scales were distributed. Back in the day, taxonomists should have paid more attention to how lizards and snakes developed together. Instead, they put them in different suborders. After molecular tools like DNA sequencing were created, scientists could begin to understand how Squamata changed over time.
Initial Challenges and Early Phylogenies:
People started questioning the old ways of putting animals into groups based on their forms after mitochondrial DNA sequences were used to make the first molecular phylogenies of Squamata. Videos and Hedges did a study in 2002 that was one of the first to use genetic information to suggest a new squamate phylogeny. There are now different ways to group plants because of this. This early work gave a fuller picture of how species in this group have changed over time.
Recent Advances and the Most Recent Phylogeny:
More recent advancements in genomics, especially the use of nuclear DNA data, have helped us learn more about how Squamata evolved. The most recent complete phylogeny for Squamata, released in 2021 by Pyron et al., uses genetic data from many genes to build a solid and well-supported framework of how the group’s members are related.
Comparison of Early and Recent Phylogenies:
Molecular data were used to build both phylogenies, but the new study’s better methods and larger sample sizes of taxa have greatly improved clarity and support values.
Figure 1: early phylogeny
The early phylogeny needed to clarify how the major clades related to each other, and some key nodes needed strong support. It was clear that Iguania and Scleroglossa, two significant suborders, were separate but only partially specific. It was still being determined where some families and genera belonged because of limited taxon sampling and reliance on mitochondrial DNA.
Figure 2: most recent phylogeny
The latest phylogeny shows Squamata connections with improved resolution and support values. Each suborder forms monophyletic groupings, supporting the split of Iguania and Scleroglossa. A broader taxon collection and nuclear DNA markers have resolved previously confusing connections, improving squamate evolution depictions.
Changes in Clade Evolution Understanding:
Refining the squamate phylogeny has changed our understanding of the evolution of the squamate clade. This transformation has led to numerous significant advances in our knowledge of this taxonomic group’s evolutionary processes. Developing cryptic diversity is substantial. Cryptic diversity was ignored in early phylogenetic studies because it took more work to determine group relationships. However, the latest phylogeny found and explained many of these complex links, advancing it. This revealed a new squamate lineage variant. It told previously undiscovered evolutionary relationships.
Reworking taxonomic groupings is another benefit of more precise phylogeny. New molecular approaches and additional taxon samples have increased resolution, necessitating reclassification. Thus, several groupings and families have been altered to represent their true evolution. This taxonomy change shows Squamata’s genetic diversity better, providing a more complete evolutionary picture. The more precise phylogeny has also led to significant Squamata development alterations. This shift, snake leg reduction, has proven fascinating to examine. We can better understand squamate evolution now that we can more accurately follow these changes along the limbs of the biological phylogeny. It is now easier to know how they have changed to fit into their natural niches, which are very important for their growth. This shows how squamates have changed and done well.
Finally, the species Squamata, including lizards and snakes, is fascinating and has a long history of development. Phylogenetic studies have improved over time, and the most recent complete phylogeny tells us a lot about how squamates evolved. Finding secret variety, taxonomic group changes, and evolutionary transitions shows how important genetic methods are for comprehending the complicated links among this massive group of reptiles.
References
Leaché, A. D., Davis, H. R., Singhal, S., Fujita, M. K., Lahti, M. E., & Zamudio, K. R. (2021). Phylogenomic assessment of biodiversity using a reference-based taxonomy: An example with horned lizards (Phrynosoma). Frontiers in Ecology and Evolution, 9. https://doi.org/10.3389/fevo.2021.678110
Vidal, N., & Hedges, S. (2002). Higher-level relationships of snakes inferred from four nuclear and mitochondrial genes. Comptes Rendus Biologies, 325(9), 977-985. https://doi.org/10.1016/s1631-0691(02)01510-x
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