Phylogenetic relationships among megabats, microbats, and primates

Area of Science:

• Evolutionary Biology
• Genomics
• Mammalian Phylogenetics

Background:

• Understanding the evolutionary relationships among mammals is crucial for reconstructing their diversification.
• Bats (microbats and megabats) represent a unique mammalian order with the evolution of powered flight.

Purpose of the Study:

• To investigate the monophyly of bats (Order Chiroptera) using molecular data.
• To resolve the evolutionary origins of flight in mammals.
• To clarify the relationship between megabats and other mammals, particularly primates.

Main Methods:

• Phylogenetic analysis of mitochondrial DNA sequences (12S rRNA and cytochrome oxidase subunit I) from a microbat (Brachyphylla cavernarum) and a megabat (Pteropus capestratus).
• Inclusion of homologous DNA sequences from human (Homo sapiens), mouse (Mus musculus), and chicken (Gallus gallus) as outgroups.
• Application of phylogenetic character weighting based on evolutionary rate differences and consideration of alternative rRNA alignment strategies.

Main Results:

• Mitochondrial DNA data strongly support bat monophyly, irrespective of variations in outgroup, gap coding, or sequence alignment order.
• Findings are consistent with morphological data (e.g., wing structure) and cladistic analyses of globin genes.
• Neurological similarities between megabats and primates are attributed to either retained ancestral traits or convergent evolution, not shared ancestry.

Conclusions:

• The study provides robust molecular evidence for the monophyly of bats.
• The evolution of flight in mammals likely occurred once.
• The perceived similarities between megabats and primates are evolutionary artifacts, not indicative of a close common ancestor.