Drosophila Females Undergo Genome Expansion after Interspecific Hybridization

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Biology

Background:

• Eukaryotic genome size varies significantly, influenced by noncoding repetitive sequences like transposable elements (TEs).
• Interspecific hybridization can activate TEs, leading to genome expansion and potentially impacting speciation.
• The effects of hybridization on genome size and TE mobilization in Drosophila remain under investigation.

Discussion:

• Hybridization and introgression in Drosophila species (D. buzzatii and D. koepferae) were studied to assess genome size changes.
• Genome size was measured in parental species, F1 hybrids, and subsequent backcrossed generations using flow cytometry.
• Mobilization of up to 28 different TEs was previously detected in these backcrossed hybrids.

Key Insights:

• Hybrid females exhibit genome expansion, most notably in the first backcross generation, linked to transposition events.
• Hybrid males do not show increased genome size, displaying more variable C-values within generations.
• Hybridization's impact on genome size is detectable via flow cytometry and demonstrates a clear sex-dependent effect.

Outlook:

• Further research can explore the specific TEs driving genome expansion and their regulatory mechanisms.
• Investigating the long-term consequences of sex-dependent genome expansion on hybrid fitness and reproductive isolation.
• Understanding the role of genome size changes in hybrid speciation across diverse taxa.