Different Evolutionary Trends of Galloanseres: Mitogenomics Analysis

Area of Science:

• Evolutionary Biology
• Genomics
• Ornithology

Background:

• Galloanseres, comprising Galliformes (landfowl) and Anseriformes (waterfowl), display divergent evolutionary trajectories.
• Mitochondria are crucial for cellular energy production and play a significant role in organismal evolution and adaptation.
• Understanding mitogenome evolution provides insights into species diversification and adaptation.

Purpose of the Study:

• To assemble and analyze the complete mitogenome sequences of two *Aythya* species (*Aythya baeri* and *Aythya marila*).
• To construct a phylogenetic tree and infer divergence times for 142 species within Galloanseres.
• To investigate evolutionary pressures and rates acting on mitochondrial protein-coding genes (PCGs) in Galliformes and Anseriformes.

Main Methods:

• Whole mitogenome sequencing of *Aythya baeri* and *Aythya marila*.
• Phylogenetic analysis and divergence time estimation using a dataset of 142 Galloanseres species.
• Selective pressure analysis using free-ratio and CmC models on mitochondrial PCGs.

Main Results:

• The divergence between Galliformes and Anseriformes occurred approximately 79.62 million years ago, with rapid diversification post-Middle Miocene (~13.82 Mya).
• Mitochondrial PCGs in Galloanseres are predominantly under purifying selection.
• Specific genes (*COX1*, *COX3*) exhibit lower evolutionary rates, while others (*ND2*, *ND6*) show faster rates; Anseriformes PCGs generally have stronger selective constraints.

Conclusions:

• Distinct evolutionary trends and differing energy requirements between Galliformes and Anseriformes shape their respective mitogenome evolutionary patterns.
• Mitochondrial genome evolution is influenced by the ecological niches and metabolic demands of avian lineages.
• The findings contribute to a deeper understanding of avian evolutionary history and adaptation at the molecular level.