Anastrepha fraterculus is recognized as a quarantine pest in several American countries. This fruit fly species is native to the American continent and distributed throughout tropical and subtropical regions. It has been reported as a complex of cryptic species, and at least eight morphotypes have been described. Only one entity of this complex, formerly named Anastrepha fraterculus sp. 1, is present in Argentina. Previous cytogenetic studies on this morphotype described the presence of sex chromosome variation identified by chromosomal size and staining patterns. In this work, we expanded the cytological study of this morphotype by analyzing laboratory strains and wild populations to provide information about the frequency and geographic distribution of these sex chromosome variants. We analyzed the mitotic metaphases of individuals from four laboratory strains and five wild populations from the main fruit-producing areas of Argentina, including the northwest (Tucumán and La Rioja), northeast (Entre Ríos and Misiones), and center (Buenos Aires) of the country. In wild samples, we observed a high frequency of X₁X₁ (0.94) and X₁Y₅ (0.93) karyomorphs, whereas X₁X₂ and X₁Y₆ were exclusively found at a low frequency in Buenos Aires (0.07 and 0.13, respectively), Entre Ríos (0.16 and 0.14, respectively) and Tucumán (0.03 and 0.04, respectively). X₂X₂ and X₂Y₅ karyomorphs were not found in wild populations but were detected at a low frequency in laboratory strains. In fact, karyomorph frequencies differed between wild populations and laboratory strains. No significant differences among A. fraterculus wild populations were evidenced in either karyotypic or chromosomal frequencies. However, a significant correlation was observed between Y₅ chromosomal frequency and latitude. We discuss the importance of cytogenetics to understand the possible route of invasion and dispersion of this pest in Argentina and the evolutionary forces acting under laboratory conditions, possibly driving changes in the chromosomal frequencies. Our findings provide deep and integral genetic knowledge of this species, which has become of relevance to the characterization and selection of valuable A. fraterculus sp. 1 strains for mass rearing production and SIT implementation.

Capuchin monkeys (generaCebusandSapajus) show a wide range distribution, from Honduras to Argentina. The aim of this work was to evaluate the genetic and phenotypic variability of captive specimens putatively belonging toS. cay(SCY) andS. nigritus(SNI) at their southernmost distribution limit. Forty-four individuals held in five captive centers from Argentina were analyzed based on external morphology, karyology and DNA sequences of mitochondrial control region (mtDNA-CR). Three morphotypes associated with their probable geographical origin in SCY and a single morphotype in SNI were found. For SCY we could associate each morphotype with the most frequent karyotype. SNI showed a single phenotype and a homogenous karyotype. Heterochromatin showed geographical patterns within species. A 515-bp mtDNA-CR fragment was sequenced, defining fourteen haplotypes at 59 polymorphic sites. A network constructed with our 14 haplotypes and other 77 fromS. apella,S. macrocephalus,S. cayandS. nigritusfrom bibliography revealed some phylogeographic signals. Our SCY and SNI samples rendered four groups that differed in multiple mutational steps, with SCY being more similar toS. apellathan toS. macrocephalus. Also, we identified two genetic divergent SCY groups: samples from NOA and from NEA with high mitochondrial diversity. Our results highlight the relevance of using complementary genetic tools throughout the distribution ranges of SCY and SNI for a better assessment of their diversity.

Cytogenetic studies in Cebus spp. have highlighted a peculiar genomic feature: the presence of conspicuous regions of extracentromeric heterochromatin distributed throughout the karyotype. This study investigates the distribution, variability and composition of heterochromatin and their possible implications for genome dynamics. We performed a molecular cytogenetic analysis in 253 individuals from seven of the 12 currently recognized species. The proportion of heterochromatin was related to genome size and ranked, from smallest to largest, from C. xanthosternos to C. albifrons. Interspecies comparative genome hybridization analyses suggested that the differences among species are not related to heterochromatin content but to changes in the Y chromosome. The pattern revealed by DAPI/CMA₃ staining showed that Cebus heterochromatic DNA has a GC-rich composition. The distribution frequencies of heteromorphisms and polymorphisms were not randomly distributed, because a distinguishable pattern could be recognized for each group. Cebus cay and C. nigritus had a higher level of heterochromatin variability than previously reported. In conclusion, the wide variability among species of the genus Cebus is mostly due to the repetitive DNA fraction of its genome.

There are extensive studies on chromosome morphology and karyotype diversity in primates, yet we still lack insight into genomic instability as a key factor underlying the enormous interspecies chromosomal variability and its potential contribution to evolutionary dynamics. In this sense, the assessment of spontaneous sister chromatid exchange (SCE) frequencies represents a powerful tool for evaluating genome stability. Here, we employed G-banding, fluorescence plus Giemsa (FPG), and chromosome orientation fluorescence in situ hybridization (CO-FISH) methodologies to characterize both chromosome-specific frequencies of spontaneously occurring SCE throughout the genome (G-SCE) and telomere-specific SCE (T-SCE). We analyzed primary fibroblast cultures from two male species of Ateles living in captivity: Ateles paniscus (APA) and Ateles chamek (ACH). High frequencies of G-SCEs were observed in both species. Interestingly, G-SCEs clustered on evolutionary relevant chromosome pairs: ACH chromosomes 1, 2, 3, 4, and 7, and APA chromosomes 1, 2, 3, 4/12, 7, and 10. Furthermore, a statistically significant difference between the observed and expected G-SCE frequencies, not correlated with chromosome size, was also detected. CO-FISH analyses revealed the presence of telomere-specific recombination events in both species, which included T-SCE, as well as interstitial telomere signals and telomere duplications, with APA chromosomes displaying higher frequencies, compared to ACH. Our analyses support the hypothesis that regions of Ateles chromosomes susceptible to recombination events are fragile sites and evolutionary hot spots. Thus, we propose SCE analyses as a valuable indicator of genome instability in non-human primates.