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Meiotic evidence for pericentric inversion polymorphism in Junco (Aves).
Canadian Journal of Genetics and Cytology. Journal Canadien De Genetique Et De Cytologie
|December 1, 1976
Summary
Chromosomal polymorphisms in Dark-eyed Juncos (Junco hyemalis) are linked to chromosome inversions. Heterozygous individuals exhibit fewer chiasmata, suggesting inversions influence recombination and genetic diversity in these bird species.
Area of Science:
- Evolutionary Biology
- Cytogenetics
- Ornithology
Background:
- The genus Junco exhibits known chromosomal polymorphisms in chromosomes 2 and 5.
- Understanding the genetic basis of these polymorphisms is crucial for evolutionary studies.
Purpose of the Study:
- To investigate the cytogenetic basis of chromosomal polymorphisms in Dark-eyed Juncos (Junco hyemalis).
- To determine the relationship between chromosomal heterozygosity and chiasma frequency.
Main Methods:
- Analysis of diplotene karyotypes from 61 adult male Dark-eyed Juncos.
- Comparison of chiasma frequencies between individuals with homozygous and heterozygous polymorphic chromosomes.
Main Results:
- Individuals with heterozygous bivalents on polymorphic chromosomes showed significantly fewer chiasmata compared to homozygous individuals.
- This reduction in chiasma frequency suggests a structural basis for the observed polymorphisms.
Conclusions:
- The study provides evidence that two separate pericentric inversions underlie the chromosomal polymorphisms in Junco species.
- These inversions likely impact meiotic recombination, potentially influencing the evolutionary dynamics of Junco populations.