The phylogeny of the Caelifera (Insecta, Orthoptera) as deduced from mtrRNA gene sequences

Area of Science:

• Evolutionary Biology
• Molecular Phylogenetics
• Entomology

Background:

• The evolutionary relationships within the grasshopper suborder Caelifera remain incompletely resolved.
• Previous classifications relied heavily on morphological data, which can be prone to homoplasy.
• Mitochondrial ribosomal RNA (rRNA) genes offer valuable markers for phylogenetic inference in insects.

Purpose of the Study:

• To reconstruct the phylogeny of Caelifera using mitochondrial ribosomal RNA gene sequences.
• To test the monophyly of traditional caeliferan superfamilies and assess evolutionary relationships.
• To investigate potential confounding factors like base composition bias in phylogenetic analyses.

Main Methods:

• Sequencing of mitochondrial ribosomal RNA genes from 32 caeliferan taxa and 6 outgroup Orthopteroids.
• Alignment of sequence data (630 bp after removing ambiguously aligned positions).
• Phylogenetic analyses using multiple methods, including LogDet transformation to address base composition bias, and construction of a consensus tree.

Main Results:

• The suborder Caelifera and most traditional superfamilies were recovered as monophyletic, with the exception of Eumastacoidea.
• Phylogenetic analysis indicated that Pamphagidae is nested within Acrididae, and Pyrgomorphidae is closely related to Pneumoroidea.
• Morphological similarities between Pyrgomorphidae and Pamphagidae are likely homoplasic, not indicative of close evolutionary relationship.

Conclusions:

• Mitochondrial rRNA gene data provide a robust framework for understanding caeliferan phylogeny, refining traditional classifications.
• The study highlights the importance of considering base composition bias in phylogenetic analyses of closely related taxa.
• The proposed phylogenetic order suggests a revised understanding of grasshopper evolution and superfamily relationships.