Estimating Diversity of Black Flies in the Simulium ignescens and Simulium tunja Complexes in Colombia: Chromosomal Rearrangements as the Core of Integrative Taxonomy.

Black flies (Diptera: Simuliidae) are distributed throughout the world, with more than 2200 formally described species. The family is renowned for its high frequency of cryptic species, offering an opportunity for integrative taxonomy, based on morphological, chromosomal, and molecular approaches. The biodiversity within Simulium (Psilopelmia) ignescens and S. (Psilopelmia) tunja in Colombia was estimated from the larval stage; 10 morphoforms were recognized based on 7 structural characters. This remarkable morphological variation was evaluated through 23 markers on the polytene chromosomes. We established 1 new cytoform in each nominal species. The congruence of the morphological and chromosomal assignments was evaluated using the mitochondrial marker Cytochrome Oxidase subunit I (COI) for each morphoform. The molecular data supported the chromosomal recognition of cytoforms (i.e., cryptic species). We also established the suitability of the COI marker for linking the pupal stage with each cytoform. Our results reveal the presence of hidden biodiversity in S. ignescens and S. tunja and demonstrate the power of polytene chromosomes as a tool for evaluating simuliid diversity, while illustrating the importance of integrated analyses in modern taxonomy.

Sex-determinatinn systems and their evolution: mammlss / Sistemas de determinación de sexo y su evolución: caso mamíferos

Sex-determination methods are very diverse as they have become an enduring research field. Understanding the causes of gonadal development and elucidating the main factors involved in sex-determination of offspring required relating information from far-ranging areas such as cytology, embryology, morphology, molecular biology and even ecology and evolution. This article presents an overview of sex-determination in placental mammals, encompassing several levels of biological organization. The importance of the underlying molecular tools in the context of sex-determination assays and their implications in conservation genetics is also discussed.

Los sistemas de determinación de sexo son muy diversos y en consecuencia se ha aumentado la investigación en este campo. Entender el desarrollo gonadal y elucidar los factores involucrados en la determinación de sexo de la descendencia ha requerido tomar información de aéreas como: citología, embriología, morfología, biología molecular e incluso de ecología y evolución. Este artículo presenta una visión de los mecanismos de determinación de sexo en mamíferos placentarios, abarcando algunos niveles de organización biológica. También se discute la importancia de las herramientas moleculares en las pruebas de determinación del sexo y sus implicaciones en conservación genética.