The Saffron finch (Sicalis flaveola), a semi-domestic species, is tolerant of human proximity and nesting in roof spaces. Considering the importance of cytogenomic approaches in revealing different aspects of genomic organization and evolution, we provide detailed cytogenetic data for S. flaveola, including the standard Giemsa karyotype, C- and G-banding, repetitive DNA mapping, and bacterial artificial chromosome (BAC) FISH. We also compared our results with the sister groups, Passeriformes and Psittaciformes, bringing new insights into the chromosome and genome evolution of birds. The results revealed contrasting rates of intrachromosomal changes, highlighting the role of SSR (simple short repetition probes) accumulation in the karyotype reorganization. The SSRs showed scattered hybridization, but brighter signals were observed in the microchromosomes and the short arms of Z chromosome in S. flaveola. BACs probes showed conservation of ancestral syntenies of macrochromosomes (except GGA1), as well as the tested microchromosomes. The comparison of our results with previous studies indicates that the great biological diversity observed in Passeriformes was not likely accompanied by interchromosomal changes. In addition, although repetitive sequences often act as hotspots of genome rearrangements, Passeriformes species showed a higher number of signals when compared with the sister group Psittaciformes, indicating that these sequences were not involved in the extensive karyotype reorganization seen in the latter.

Anseriformes represent a basal order in the phylogeny of neognath birds and are of particular interest in cytogenetic research due to their distinctive chromosomal features. However, aspects of their chromosomal evolution, such as the distribution and organization of microsatellite sequences, remain poorly understood. Given the role of these dynamic repetitive sequences in chromosome organization, differentiation, and evolution, we analyzed microsatellite distribution in three Anatidae species, each representing a different subfamily: Amazonetta brasiliensis-Brazilian Teal (Anatinae), Coscoroba coscoroba-Coscoroba Swan (Anserinae), and Dendrocygna viduata-White-faced Whistling Duck (Dendrocygninae). This is the first karyotypic description for White-faced Whistling Duck (2n = 78) and Brazilian Teal (2n = 80), whereas Coscoroba Swan, previously analyzed, exhibits a notably high diploid number (2n = 98). Despite sharing a similar macrochromosome morphology, the three showed differences in diploid numbers and microsatellite distribution. Extensive microsatellite accumulation was found in both autosomal and sex chromosomes (Z and W) of Brazilian Teal and Coscoroba Swan, while White-faced Whistling Duck displays minimal hybridization signals and an absence of microsatellites on the sex chromosomes. The accumulation of specific microsatellites, such as (CAC)₁₀ and (GAG)₁₀, in centromeric and pericentromeric regions suggests an association with transposable elements, potentially driving chromosomal evolution. Notably, the substantial accumulation of these sequences on the Z and W chromosomes of Brazilian Teal and Coscoroba Swan, but not White-faced Whistling Duck, supports the hypothesis that repetitive sequence expansion occurs in a species-specific manner, contributing to sex chromosome differentiation. These findings highlight microsatellite mapping as a valuable tool for understanding chromosomal evolution and genomic differentiation in Anseriformes.

Resumo Pouco se sabe sobre a organização de sequências repetitivas no cariótipo das Aves, e sondas de microssatélites foram usadas em um pequeno grupo de espécies até o momento. Tyrannidae (Passeriformes, Suboscines), é uma das maiores famílias de aves das Américas, e dados citogenéticos evidenciaram uma interessante variação cariotípica nesse grupo. Assim, o objetivo desse estudo foi analisar o cariótipo da guaracava-de-barriga-amarela (Elaenia flavogaster), por meio de técnicas de citogenética clássica (coloração convencional com Giemsa e bandeamento C) e molecular (sondas teloméricas, 18S rDNA e sondas de microssatélites: (CAT)₁₀, (GAG)₁₀, (GC)₁₅, (GA)₁₅ e (TA)₁₅). Os resultados mostraram um número diploide de 2n=80. A distribuição da heterocromatina exibiu marcações apenas nos centrômeros dos cromossomos. O padrão de hibridização das sondas teloméricas revelou sinais mais intensos nos microcromossomos e ausência de sequências teloméricas intersticiais (ITSs), reforçando o fato de que ITSs são menos frequentes em ordens de Aves consideradas mais derivadas, visto que em Ratitas e Galloanserae essas sequências já foram detectadas. As sondas de 18S rDNA marcaram dois pares de microcromossomos, semelhante a Elaenia spectabilis e Serpophaga subcristata, indicando que esta característica pode representar uma sinapomorfia dentro de Elaeniinae, pois até o momento não foi encontrada em outras subfamílias dentro de Tyrannidae. Das sondas de microssatélites utilizadas, (GA)₁₅ e (TA)₁₅ não produziram sinais detectáveis, já as sondas de microssatélites (CAT)₁₀ marcaram apenas na extremidade distal do braço longo do 1º par, e em alguns microcromossomos, as sondas (GAG)₁₀ apresentaram intensa marcação nos microcromossomos, diferentemente de Leptotila verreauxi (Columbiformes), na qual essas sondas marcam poucos microcromossomos. Já as sondas (GC)₁₅ marcaram apenas o braço curto de um microcromossomo e o braço longo de um macrocromossomo. Esses resultados evidenciam a variação de distribuição dessas sequências repetitivas em diferentes grupos de Aves e o pequeno número de sinais detectados concorda com o fato de que o genoma das Aves é compacto com pouca quantidade de DNA repetitivo. Conclui-se que a evolução do cariótipo dos tiranídeos envolveu a amplificação de sítios de 18S rDNA e que apresenta uma distribuição distinta de microssatélites quando comparada com espécies de outras ordens.

O ENEBIO MUDOU! Em um ano em que fomos surpreendidos por restrições de interação presencial devido a pandemia, abraçamos a oportunidade de nos reinventarmos. E por isso a oitava edição do Encontro Nacional de Ensino de Biologia (VIII ENEBIO), ocorrer&

Chromosome painting has proven to be an essential tool for elucidating the evolutionary mechanisms underlying avian karyotype diversification and for identifying key synapomorphies that enhance our understanding of avian phylogenetic relationships. In the Neotropical region, the family Tyrannidae exhibits the greatest species diversity, providing valuable opportunities to investigate chromosomal evolution among closely related taxa. To contribute to our understanding of chromosomal evolution within Tyrannidae, we analyzed the karyotypes of two representative species, Myiozetetes cayanensis and Lathrotriccus euleri, combining classical cytogenetic techniques with fluorescence in situ hybridization. We employed whole-chromosome probes from Gallus gallus (GGA) and Leucopternis albicollis (LAL), as well as 18S rDNA and telomeric repeats (TTAGGG) _n probes. Our results revealed the conserved karyotypic structure characteristic of Passeriformes (approximately 80 chromosomes), with M. cayanensis exhibiting 2n = 80 and Lathrotriccus euleri 2n = 78. In both species, the karyotypes are predominantly composed of acrocentric chromosomes. Telomeric probes produced signals restricted to terminal chromosomal regions, while 18S rDNA probes hybridized to a single pair of microchromosomes. Probes from GGA and LAL revealed chromosomal fissions and inversions in both species. Similar rearrangements have been observed in other tyrannid species from the subfamilies Fluvicolinae, Tyranninae, and Elaeniinae, suggesting a possible shared evolutionary pattern within Tyrannidae.