Phylogeographic evidence for two species of muriqui (genus Brachyteles)

Observations on the anatomy of the funiculus spermaticus and the testis in Brachyteles sp. (SPIX, 1823) primates - Atelidae

BACKGROUND

Analysing the literature about the reproductive anatomy on New World Primates, one can see the need of standardisation on the description methods and, more importantly, the lack of detailed information. The problem is aggravated by the difficult access to specimens of the endangered species such as Brachyteles sp. This paper's objective was to extend knowledge on the male reproductive anatomy of these primates. The testis and funiculus spermaticus of Brachyteles are described in detail.

METHODS

We utilised one individual of Brachyteles arachnoides, two hybrids (B. arachnoides × Brachyteles hypoxanthus) and photographs of the testis of a third fresh specimen of a hybrid individual.

RESULTS

The septum formed by tunica dartos adheres to the testis and separates the scrotum in two testicular cavities. Passed the spermatic cord, the external spermatic fascia continues with the tunica dartos, covering the cranial half of the testis. The fascia cremasterica divides itself in bundles of fibres and forms loops around the testicles creating a sac like structure that seems to be unique among Neotropical Primates. The appendix testis is described for the first time in platyrrhini. It is presented as a sessile structure in the extremitas capitata of the testis. Previous literature on the reproductive anatomy of platyrrhini is limited. Despite that, it can be said that the large size and volume of the testis, and complex structure of the cremaster, could consist of a heat loss reduction strategy in cold and humid forest environments.

CONCLUSIONS

Except for the larger size of the testicles in hybrid individuals, no other significant morphological differences were found between B. arachnoides and hybrids (B. arachnoides × B. hypoxanthus).

Phylogeography, genetic diversity, and intraspecific genetic structure of the black-horned capuchin (Sapajus nigritus)

Recent molecular studies have clarified the overarching taxonomy of capuchin monkeys, but intraspecific genetic diversity remains unexplored for most capuchin species. One example is Sapajus nigritus, the southernmost capuchin monkey, found in Brazil and Argentina; its phenotypic diversity has been recognized as two geographic subspecies, but the intraspecific genetic structure of this taxon is poorly known. Here, we sampled across most of this species' geographic distribution, producing a newly sequenced data set for genetic analyses that included 78 individuals from 14 populations. We investigated the intraspecific diversity, genetic structure, and evolutionary history using three mitochondrial markers. Our results indicated that S. nigritus populations exhibited high levels of genetic structure. We found strong support for two monophyletic clades within this species with a deep phylogenetic split, and clear separation from other related taxa. Vicariance events seem to have played a prevalent role in shaping S. nigritus genetic differentiation. The Paraíba do Sul River may have driven the deep divergence between southern and northern clades, whereas the Tietê River may have had a weaker, more recent effect on the divergence of populations within the southern clade.

First record of the southern muriqui (Brachyteles arachnoides) in the state of Minas Gerais, Brazil

The Critically Endangered southern muriqui (Brachyteles arachnoides) and its sister taxon the northern muriqui (Brachyteles hypoxanthus) are endemic to the Atlantic Forest in Brazil. To date, our understanding of the distribution of the southern muriqui has restricted it to the states of Paraná, São Paulo, and Rio de Janeiro. The northern muriqui occurs in the states of Minas Gerais, Rio de Janeiro, Espírito Santo, and Bahia. Here, we describe the first record of the southern muriqui in Minas Gerais. A group of seven individuals, including one infant, was detected and photographed on  a private property in the district of Monte Verde, municipality of Camanducaia, on the northwestern slope of the Serra da Mantiqueira. This location is 5.3 km from a population of southern muriquis (known since 1994) on the southeastern slope of the serra in São Paulo. This discovery highlights the importance of further surveys in the Serra da Mantiqueira in order to detect any new populations, provide data for a more accurate assessment of the conservation status of the two species-the delimitation of their distributions, the size and extent of isolation of their populations, and the threats they face.

The life of a naturalist

This essay summarizes some of my findings while studying primates in the field from 1962 to 2018. Although I have studied primates throughout the tropics, I focused on Africa, primarily the Kibale Forest of Uganda. My research began in the early days of primate field studies when very little was known about the behavior and ecology of most species. Consequently, I was able to study nearly anything that could be observed under natural conditions. It was not necessary to specialize, and I opted to be a generalist. In much of my work I have attempted to understand the relationships between habitat quality, social organization, and population dynamics, emphasizing the great intraspecific variability that exists over time and between areas. Vocalizations have also long been of interest to me, starting with a description of predator-specific alarm calls and later showing how vocalizations among African monkeys appear to be evolutionarily stable. As my field experience progressed, I became increasingly involved with the conservation of tropical rain forests. In the last part of this essay I offer my thoughts on current trends in field primatology and some advice to the next generation of field biologists, stressing the importance of being a naturalist.

Transcriptome of the Southern Muriqui Brachyteles arachnoides (Primates:Platyrrhini), a Critically Endangered New World Monkey: Evidence of Adaptive Evolution

The southern muriqui (Brachyteles arachnoides) is the largest neotropical primate. This species is endemic to Brazil and is currently critically endangered due to its habitat destruction. The genetic basis underlying adaptive traits of New World monkeys has been a subject of interest to several investigators, with significant concern about genes related to the immune system. In the absence of a reference genome, RNA-seq and de novo transcriptome assembly have proved to be valuable genetic procedures for accessing gene sequences and testing evolutionary hypotheses. We present here a first report on the sequencing, assembly, annotation and adaptive selection analysis for thousands of transcripts of B. arachnoides from two different samples, corresponding to 13 different blood cells and fibroblasts. We assembled 284,283 transcripts with N50 of 2,940 bp, with a high rate of complete transcripts, with a median high scoring pair coverage of 88.2%, including low expressed transcripts, accounting for 72.3% of complete BUSCOs. We could predict and extract 81,400 coding sequences with 79.8% of significant BLAST hit against the Euarchontoglires SwissProt dataset. Of these 64,929 sequences, 34,084 were considered homologous to Supraprimate proteins, and of the remaining sequences (30,845), 94% were associated with a protein domain or a KEGG Orthology group, indicating potentially novel or specific protein-coding genes of B. arachnoides. We use the predicted protein sequences to perform a comparative analysis with 10 other primates. This analysis revealed, for the first time in an Atelid species, an expansion of APOBEC3G, extending this knowledge to all NWM families. Using a branch-site model, we searched for evidence of positive selection in 4,533 orthologous sets. This evolutionary analysis revealed 132 amino acid sites in 30 genes potentially evolving under positive selection, shedding light on primate genome evolution. These genes belonged to a wide variety of categories, including those encoding the innate immune system proteins (APOBEC3G, OAS2, and CEACAM1) among others related to the immune response. This work generated a set of thousands of complete sequences that can be used in other studies on molecular evolution and may help to unveil the evolution of primate genes. Still, further functional studies are required to provide an understanding of the underlying evolutionary forces modeling the primate genome.