Comparing Small and Large Genomes Within Monogonont Rotifers

Area of Science:

• * Evolutionary biology
• * Genomics
• * Animal physiology

Background:

• * Genome size influences biological traits like body size and metabolic rate.
• * Understanding genome size variation requires broader taxonomic sampling, especially in nonmodel organisms like monogonont rotifers.
• * Previous studies were limited by sparse genomic data in the phylum Rotifera.

Purpose of the Study:

• * To estimate genome sizes for nine monogonont rotifer species using Nanopore sequencing and flow cytometry.
• * To investigate the relationship between genome size, body size, and metabolic rate in rotifers.
• * To identify the genomic mechanisms driving genome size variation in this group.

Main Methods:

• * High-throughput Nanopore sequencing for genome assembly.
• * Flow cytometry for independent genome size estimation.
• * Respirometry to measure oxygen consumption as a proxy for metabolic rate.
• * Comparative analysis of genome size with body size and metabolic rate data.

Main Results:

• * Consistent genome size estimates were obtained from both sequencing and flow cytometry.
• * Genome size was positively correlated with both body size and size-specific respiration rate.
• * Genome size variation was not explained by repetitive elements or large duplications.
• * Increased genome size correlated with a higher number of predicted proteins, many with unknown functions.

Conclusions:

• * Genome size in monogonont rotifers is linked to body size and metabolic rate.
• * The primary driver of genome size increase appears to be an expansion of predicted proteins, rather than repetitive DNA.
• * This research significantly broadens the genomic resources for the phylum Rotifera, enabling future studies on evolutionary and ecological genetics.