Interspecific hybridization allows the introgression or movement of alleles from one genome to another. While some genomic regions freely exchange alleles during hybridization, loci associated with reproductive isolation do not intermix. In many model organisms, the X chromosome displays limited introgression compared to autosomes owing to the presence of multiple loci associated with hybrid sterility or inviability (the “large X-effect”). Similarly, if hybrids are produced, the heterogametic sex is usually inviable or sterile, a pattern known as Haldane’s rule. We analyzed the patterns of introgression of genetic markers located in the mitochondrial (control region) and nuclear (autosomal microsatellites and sex chromosome genes) genomes of two howler monkey species ( Alouatta palliata and A. pigra ) that form a natural hybrid zone in southern Mexico, to evaluate whether the large X-effect and Haldane’s rule affect the outcomes of hybridization between these sister species. To identify the level of admixture of each individual in the hybrid zone ( N = 254) we analyzed individuals sampled outside the hybrid zone (109 A. pigra and 39 A. palliata ) to determine allele frequencies of parental species and estimated a hybrid index based on nuclear markers. We then performed a cline analysis using individuals in the hybrid zone to determine patterns of introgression for each locus. Our analyses show that although the hybrid zone is bimodal (with no known F1 s and few recent generation hybrids) and quite narrow, there has been extensive introgression in both directions, and there is a large array of admixed individuals in the hybrid zone. Mitochondrial and most autosomal markers showed bidirectional introgression, but some had biased introgression toward one species or the other. All markers on the sex chromosomes and a few autosomal markers showed highly restricted introgression. This pattern is consistent with the hypothesis that the sex chromosomes make a disproportionate contribution to reproductive isolation, and our results broaden the taxonomic representation of these patterns across animal taxa. Electronic supplementary material The online version of this article (10.1007/s10764-018-0056-4) contains supplementary material, which is available to authorized users.

In general, measured parameters are similar to those of other primates and will be used as reference values for futures studies.

We describe for the first time the karyotype of the black howler monkey, Alouatta pigra. Conventional staining, G- and C-banding, and fluorescence in situ hybridization (FISH) with a peptide nucleic acid (PNA) pantelomeric probe were performed. Eight free ranging adult individuals, four males and four females, within the natural distribution of the species presented a diploid karyotype with 2n = 58. Mitotic analyses showed an autosomal complement composed of 6 submetacentric, 3 metacentric, and 19 acrocentric chromosome pairs for females, and 6 submetacentric, 3 metacentric, and 18 acrocentric pairs for males. Meiotic analyses in males revealed 27 autosomal bivalents and a quadrivalent composed of a submetacentric X₁ and acrocentric X₂, Y₁, and Y₂. The G-banded karyotype allowed us to identify pair #17 as the autosomal pair involved in the rearrangement and the morphology of the quadrivalent components. C-banding technique in metaphase I corroborated the structure of the quadrivalent showing four C+ centromeres. FISH analysis showed telomeric signals at the terminal regions of all chromosomes. No interstitial signals were detected. DNA sequence data were in accordance with those previously published for this species.

Our results suggest that ketamine appears to have little effect on the hematology and blood biochemistry of Alouatta pigra females with respect to those reported for other non-human primates. It is also important to consider the elapsed time after their application when taking blood samples for proper interpretation of the hemogram of Alouatta pigra females.

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Clinical analyses of Procyonidae groups are extremely limited. The aim of this work was to obtain gender baseline data on the blood chemistry and hematological values of Nasua narica, in conditions of semi-freedom. For this, 14 males adults and 30 females adults were sedated with ketamine hydrochloride and captured. The blood was collected from the femoral artery, and conventional techniques were used to analyze the samples. Males showed statistical differences in hemoglobin, hematocrit and erythrocytes, compared to females. The females on the other hand having higher platelet counts than the males. For blood chemistry, the females showed higher concentrations of magnesium compared with the males. On the other hand, the males showed higher values in Albumin/Globulin relation with respect to the females. These results could be useful as reference values for adult individuals of Nasua narica, in order to develop future criteria regarding the health-disease processes of this species.