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Chromosomal evolution in the South American Riodinidae (Lepidoptera: Papilionoidea)
Keith S Brown1, Barbara von Schoultz, Anja O Saura
1Museu de História Natural and Departamento de Zoologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
Hereditas
|September 13, 2012
Summary
The Riodinidae butterfly family exhibits extensive and unusual variation in chromosome numbers, unlike the stable patterns seen in most Lepidoptera. This diversity may be driven by small, isolated populations and unique behaviors, potentially aiding speciation.
Area of Science:
- * Genetics
- * Evolutionary Biology
- * Entomology
Background:
- * Chromosome numbers in Lepidoptera are generally stable, with variation typically limited to subfamilies or genera.
- * The Riodinidae family's karyotype diversity was previously poorly understood.
- * Neotropical Lycaenidae (Theclinae and Polyommatinae) serve as a comparative group with known chromosomal characteristics.
Purpose of the Study:
- * To determine the haploid chromosome numbers for 173 Riodinidae species/subspecies.
- * To compare Riodinidae chromosome variation with that of 17 neotropical Lycaenidae species/subspecies.
- * To investigate the evolutionary factors contributing to observed chromosomal diversity in Riodinidae.
Main Methods:
- * Karyological analysis to determine haploid chromosome counts (n).
- * Comparative analysis of chromosome number data across Riodinidae and Lycaenidae families.
- * Statistical examination of chromosome number distribution and patterns within Riodinidae.
Main Results:
- * Riodinidae species exhibit a wide range of haploid chromosome numbers (n=9 to n=110), with numbers above n=31 being rare.
- * Unlike other Lepidoptera, Riodinidae shows significant chromosomal variation within genera, tribes, and subfamilies, lacking a single modal number.
- * A stepwise pattern of chromosome numbers, appearing as even multiples, was observed in several unrelated Riodinidae genera.
- * Neotropical Lycaenidae consistently showed the modal number of n=24, characteristic of the family.
Conclusions:
- * The extensive chromosomal variation in Riodinidae suggests unique evolutionary dynamics within the family.
- * Small, fragmented populations with limited migration and specific behaviors are proposed as drivers of this variation.
- * Inbreeding in small populations may facilitate the fixation of new chromosomal variants, promoting reproductive isolation and speciation.
- * The Riodinidae's chromosomal instability contrasts sharply with the stability observed in neotropical Lycaenidae.
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