Ecología molecular y diversidad parasitaria de poblaciones silvestres de las especies de mono aullador Aloutta palliata y A. pigra en Mesoamérica

Resum

Abstract In this thesis, two species of howler monkeys belonging to the genus Alouatta, with different habitat preferences and differences in group&apos;s composition were analysed in climate change scenarios to determine the state of conservation and health of wild populations in habitat remnants through molecular (mitochondrial and nuclear DNA) and parasitic approaches. This study should serve as an initial point for proposing, management plans for habitat conservation for these two threatened species. In the first chapter, population structure, genetic diversity and connectivity of populations of the species, Alouatta palliata and A. pigra in Mexico were analysed, with the aim to (1) provide a phylogeography pattern, genetic diversity and structure; (2) identify zones of hybridization and introgression patterns of both species, using genetic and ecological niche models; (3) clarify the gene flow and genetic connectivity in the hybridization zone and (4) compare genetic diversity in zones with different landscape&apos;s characteristics. Ecological niche models were generated for both species in several climatic scenarios (Last Glacial Maximum, Middle Holocene, Present and Future). Genetic diversity, population structure, gene flow and spatial connectivity between mitochondrial (cytb and ATPase), and nuclear fragments (Sry) and 10 microsatellites were analyzed. The effects of landscape variables on genetic differentiation were explored. The potential distribution of A. palliata and A. pigra indicates a distinct response to climate changes whereas a hybridization zone is maintained over time. The models predict that A. palliata will have a reduced potential niche compared to A. pigra. Both species present low genetic diversity, but similar to previously reported. Alouatta palliata and A. pigra populations are not in Hardy-Weinberg equilibrium, probably as a result of inbreeding. Three main groups were identified, both the parental species and hybrid individuals distributed in an extensive area of hybridization in Tabasco. Highland populations remote from each other exhibit high connectivity, while the closest lowland populations differed genetically, possibly due to habitat loss and fragmentation. It is therefore crucial to preserve the remaining fragments and to promote conservation efforts to regenerate the restoration of the connectivity of the populations of these endangered howler monkeys. In chapter two, the effects of habitat loss and hybridization in gastrointestinal parasites prevalence and richness between the two parapatric species, Alouatta palliata and A. pigra were analysed. The differential response of richness and prevalence of endoparasites was evaluated depending on a) host specificity b) the degree of hybridization, c) habitat features and d) on fragmentation level. Differences in parasite richness and prevalence were found among the regions, the host species and among the genetic origin. Correlations between environmental variables and parasite-specific prevalence were detected. Several parameters of habitat alterations such as the size of the patch or the index of surrounding use pressure are related to the prevalence and richness of the endoparasite, without a clear relation with the fragmentation. This is the first study to test genetically the combined effects of habitat perturbation and hybridization on the richness and prevalence of parasites between A. palliata and A. pigra. Detailed studies are required to discern the synergistic effect of both factors. In chapter three, the genetic variability and host specificity of the parasite Blastocystis spp. in wild howler monkeys from Mexico were analysed for infection. The howler monkeys were surveyed using a region of the small subunit rDNA (SSUrDNA) gene as a marker, comparing the sequences obtained with those in GenBank from human and non-human primates (NHP) to be used as references. The identification of a generalist or specialist profile of a parasite for its host is relevant for understanding its prevalence, transmission and other biological features. Therefore, the aim of the study was to assess the genetic variability and host specificity of Blastocystis spp. populations in the two howler monkey species A. palliata and A. pigra. Blastocystis ST2 (subtype 2) was the most abundant (91.9%), followed by ST1 and ST8 with 4.6% and 3.5%, respectively. There is no association between Blastocystis subtypes and Alouatta species. In the analyses GenBank SSUrDNA sequences from human and non-human primates (NHP) were used as reference. The nucleotide and haplotype diversity values, as well as the migration and genetic differentiation indices, showed different values for ST1 and ST2. The populations of ST1 are minimally differentiated, whereas those of ST2 in humans are highly differentiated from those of NHP. The specificities of generalist and host specialist shown by populations of Blastocystis ST1 and ST2 indicate different adaptation processes. Because ST1 exhibits a generalist profile, this haplotype could be considered a metapopulation. In contrast, ST2 is presented as a set of local populations with preferences for both humans and NHPs and with high mutational differences. In chapter four, the presence of Entamoeba spp. in scats of A. palliata and A. pigra from Mexico was analysed using molecular approaches. Universal oligonucleotides designed for Entamoeba species based on the consensus sequences of the 18S small subunit ribosomal RNA gene were tested according to the highly conserved regions reported in GenBank and PCR conditions were optimized. The objective of the study was to clarify the genetic relationships of Entamoeba spp. Detected in A. palliata and A. pigra, with other species of Entamoeba, which parasitize other vertebrates. A new Entamoeba clade was detected, which separated from other described species, although it had a position closer to E. insolita, as well as to a sequence typically found in iguanas with low values of shared identity (<90%). We designated this new clade as ribosomal lineage 8 (RL8) and demonstrated that members of this group are not exclusive to reptiles.t safety.