Chromosomal evolution in the South American Nymphalidae

Area of Science:

• * Entomology
• * Cytogenetics
• * Evolutionary Biology

Background:

• * The Nymphalidae family (brush-footed butterflies) is diverse, with varying chromosome numbers across its subfamilies.
• * Previous research established modal chromosome numbers in Lepidoptera, suggesting a conserved ancestral state.

Purpose of the Study:

• * To document chromosome numbers for numerous Neotropical Nymphalidae species.
• * To compare karyotype diversity within Neotropical taxa against other butterfly groups and related orders.

Main Methods:

• * Chromosome counting was performed on approximately 80 species and subspecies across various Nymphalidae subfamilies.
• * Data from previous studies on Afrotropical species, Heliconiini, Danainae, and Neotropical Satyroid taxa were integrated.

Main Results:

• * Chromosome numbers (n) were reported for Libytheinae (n≈32), Biblidinae (n≈31), Apaturinae (n≈31), Nymphalinae (n≈31), Limenitidinae (n=30), and Heliconiinae (n≈31).
• * The modal lepidopteran chromosome number (n=29-31) appears ancestral within Nymphalidae.
• * Neotropical taxa demonstrate a notable tendency towards karyotype instability, contrasting with stable chromosome numbers in Lepidoptera and Trichoptera.

Conclusions:

• * The ancestral Nymphalidae karyotype (n=29-31) has undergone diversification, leading to varied chromosome numbers in different lineages.
• * Neotropical Nymphalidae exhibit unique evolutionary pressures leading to karyotypic instability, a significant departure from general patterns in related insect orders.