Comparing chromosomal and mitochondrial phylogenies of the Indriidae (Primates, Lemuriformes)

The Malagasy primate family Indriidae comprises three genera with up to 19 species. Cytogenetic and molecular phylogenies of the Indriidae have been performed with special attention to the genus Propithecus. Comparative R-banding and FISH with human paints were applied to karyotypes of representatives of all three genera and confirmed most of the earlier R-banding results. However, additional chromosomal rearrangements were detected. A reticulated and a cladistic phylogeny, the latter including hemiplasies, have been performed. Cladistic analysis of cytogenetic data resulted in a phylogenetic tree revealing (1) monophyly of the family Indriidae, (2) monophyly of the genus Avahi, (3) sister–group relationships between Propithecus diadema and Propithecus edwardsi, and (4) the grouping of the latter with Indri indri, Propithecus verreauxi, and Propithecus tattersalli, and thus suggesting paraphyly of the genus Propithecus. A molecular phylogeny based on complete mitochondrial cytochrome b sequences of 16 species indicated some identical relationships, such as the monophyly of Avahi and the sister–group relationships of the eastern (P. diadema and P. edwardsi) to the western Propithecus species (P. verreauxi, Propithecus coquereli, and P. tattersalli). However, the main difference between the molecular and cytogenetic phylogenies consists in an early divergence of Indri in the molecular phylogeny while in the chromosomal phylogeny it is nested within Propithecus. The similarities and differences between molecular and cytogenetic phylogenies in relation to data on the species’ geographic distributions and mating systems allow us to propose a scenario of the evolution of Indriidae. Chromosomal and molecular processes alone or in combination created a reproductive barrier that was then followed by further speciation processes

Coordinate invariance as a fundamental constraint on the form of stimulus-specific information measures

The value of Shannon’s mutual information is commonly used to describe the total amount of information that the neural code transfers between the ensemble of stimuli and the ensemble of neural responses. In addition, it is often desirable to know which features of the stimulus or response are most informative. The literature offers several different decompositions of the mutual information into its stimulus or response-specific components, such as the specific surprise or the uncertainty reduction, but the number of mutually distinct measures is in fact infinite. We resolve this ambiguity by requiring the specific information measures to be invariant under invertible coordinate transformations of the stimulus and the response ensembles. We prove that the Kullback–Leibler divergence is then the only suitable measure of the specific information. On a more general level, we discuss the necessity and the fundamental aspects of the coordinate invariance as a selection principle. We believe that our results will encourage further research into invariant statistical methods for the analysis of neural coding

Hybridization in howler monkeys: current understanding and future directions

Hybridization, or the process by which individuals from genetically distinct populations (e.g., species, subspecies) mate and produce at least some offspring, is of great relevance to understanding the basis of reproductive isolation and, in some cases, the origins of biodiversity. Natural hybridization among primates has been well known for a few taxa, but just recently the genetic confirmation of hybridization on a number of taxa has produced new awareness of the prevalence of this phenomenon in primates and its importance in primate evolution. The study of hybridization of Alouatta pigra and A. palliata in Mexico was among the first to genetically confirm the current occurrence of hybridization in primates. Following this study, other reports of hybridization across primate taxa have shown that this phenomenon is more widespread in the Primate order than was initially expected. Within the genus Alouatta, there have been reports on the presence of hybridization between A. caraya and A. guariba in a number of contact zones in Brazil and Argentina, and various studies are currently ongoing in some of these sites to understand the extent and patterns of hybridization between these species. In this chapter, we evaluate the extent of hybridization in the genus Alouatta, revise the current knowledge of the genetic and morphological aspects of these hybrid systems, and identify future directions in the study of hybridization within this genus, to understand the possible implications of the hybridization process in the evolutionary history of howler monkeys.Fil: Cortés Ortiz, Liliana. University of Michigan; Estados UnidosFil: Agostini, Ilaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina. Centro de Investigaciones del Bosque Atlántico; ArgentinaFil: Aguiar, Lucas M.. Universidade Federal da Integração Latinoamericana; BrasilFil: Kelaita, Mary. University of Texas; Estados UnidosFil: Silva, Felipe Ennes. Instituto de Desenvolvimento Sustentável Mamirauá; BrasilFil: Bicca Marques, Julio Cesar. Pontificia Universidade Catolica Do Rio Grande Do Sul. Facultad de Biociencias; Brasi