Chromosome evolution in Neotropical butterflies

Area of Science:

• * Evolutionary Biology
• * Cytogenetics
• * Entomology

Background:

• * Chromosome number variation is a key factor in understanding butterfly speciation.
• * Previous studies have established modal chromosome numbers for many Lepidoptera species, typically ranging from n = 29-31.
• * Neotropical butterfly karyotypes remain less explored, particularly within the Hesperiidae and Pieridae families.

Purpose of the Study:

• * To document chromosome numbers for 65 Neotropical Hesperiidae and 104 Pieridae species/subspecies.
• * To analyze karyotype diversity within specific tribes and subfamilies of these families.
• * To contextualize these findings within the broader dataset of over 1400 Neotropical butterfly species.

Main Methods:

• * Karyotyping of butterfly specimens from Neotropical regions.
• * Statistical analysis of chromosome number data to determine modal numbers for various taxa.
• * Comparative analysis with existing cytogenetic data for Lepidoptera.

Main Results:

• * Hesperiidae show modal numbers of n = 28 (Pyrrhopygini), n = 31 (Eudaminae, Pyrgini), and around n = 29 (Hesperiinae).
• * Pieridae exhibit modal numbers of n = 31 (Coliadinae), n = 15 (Anthocharidini), and n = 26 (Pierini), with Dismorphiinae showing wide variation.
• * Neotropical butterfly groups display significant karyotype instability, unlike the conserved numbers in other Lepidoptera.

Conclusions:

• * Neotropical butterflies exhibit a higher degree of karyotype instability compared to other Lepidoptera, with multiple derived modal numbers or lack thereof.
• * Speciation in these groups may be influenced by biotic interactions, leading to the fixation of chromosome number changes.
• * Factors such as population subdivision, hybridization, migration, and sexual selection likely play roles in karyotype evolution and stabilization.