Matching Items (3)

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Natural and Anthropogenic Hybridization in Two Species of Eastern Brazilian Marmosets (Callithrix jacchus and C. penicillata)

Description

Animal hybridization is well documented, but evolutionary outcomes and conservation priorities often differ for natural and anthropogenic hybrids. Among primates, an order with many endangered species, the two contexts can

Animal hybridization is well documented, but evolutionary outcomes and conservation priorities often differ for natural and anthropogenic hybrids. Among primates, an order with many endangered species, the two contexts can be hard to disentangle from one another, which carries important conservation implications. Callithrix marmosets give us a unique glimpse of genetic hybridization effects under distinct natural and human-induced contexts. Here, we use a 44 autosomal microsatellite marker panel to examine genome-wide admixture levels and introgression at a natural C. jacchus and C. penicillata species border along the Sao Francisco River in NE Brazil and in an area of Rio de Janeiro state where humans introduced these species exotically. Additionally, we describe for the first time autosomal genetic diversity in wild C. penicillata and expand previous C. jacchus genetic data. We characterize admixture within the natural zone as bimodal where hybrid ancestry is biased toward one parental species or the other. We also show evidence that Sao Francisco River islands are gateways for bidirectional gene flow across the species border. In the anthropogenic zone, marmosets essentially form a hybrid swarm with intermediate levels of admixture, likely from the absence of strong physical barriers to interspecific breeding. Our data show that while hybridization can occur naturally, the presence of physical, even if leaky, barriers to hybridization is important for maintaining species genetic integrity. Thus, we suggest further study of hybridization under different contexts to set well informed conservation guidelines for hybrid populations that often fit somewhere between "natural" and "man-made."

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Date Created
  • 2015-06-10

Validation of qPCR Methods for the Detection of Mycobacterium in New World Animal Reservoirs

Description

Zoonotic pathogens that cause leprosy (Mycobacterium leprae) and tuberculosis (Mycobacterium tuberculosis complex, MTBC) continue to impact modern human populations. Therefore, methods able to survey mycobacterial infection in potential animal hosts

Zoonotic pathogens that cause leprosy (Mycobacterium leprae) and tuberculosis (Mycobacterium tuberculosis complex, MTBC) continue to impact modern human populations. Therefore, methods able to survey mycobacterial infection in potential animal hosts are necessary for proper evaluation of human exposure threats. Here we tested for mycobacterial-specific single- and multi-copy loci using qPCR. In a trial study in which armadillos were artificially infected with M. leprae, these techniques were specific and sensitive to pathogen detection, while more traditional ELISAs were only specific. These assays were then employed in a case study to detect M. leprae as well as MTBC in wild marmosets. All marmosets were negative for M. leprae DNA, but 14 were positive for the mycobacterial rpoB gene assay. Targeted capture and sequencing of rpoB and other MTBC genes validated the presence of mycobacterial DNA in these samples and revealed that qPCR is useful for identifying mycobacterial-infected animal hosts.

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Created

Date Created
  • 2015-11-16

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Hybridization and speciation in common and black-tufted marmosets (Callithrix jacchus and C. penicillata)

Description

As an evolutionary force, hybridization outcomes include introgression, admixture, speciation, and reproductive isolation. While hybridization has been studied in several primates, the marmoset genus Callithrix is an important, but little

As an evolutionary force, hybridization outcomes include introgression, admixture, speciation, and reproductive isolation. While hybridization has been studied in several primates, the marmoset genus Callithrix is an important, but little studied example of Neotropical hybridization. Varying degrees of reproductive isolation exist between Callithrix species, and hybridization occurs at species borders or regions containing introduced and native species. Interbreeding between Callithrix species carries important implications for biodiversity and genetic integrity within the genus. However, species origins and levels of genetic admixture in marmoset hybrid zones are generally unknown, and few population genetic studies of individual Callithrix species exist. Using the mitochondrial control region and 44 microsatellite markers, this work explored the genetic diversity and species origins of two C. penicillata and C. jacchus hybrid zones, as well as genetic diversity and divergence in the parental species. Both marker types showed that C. penicillata is more genetically diverse than C. jacchus. Based on mtDNA, C. jacchus seems to have experienced a past population expansion and C. penicillata evolved under constant population size. The data revealed the existence of a previously undocumented natural hybrid zone along the São Francisco River in NE Brazil and confirmed species origins of an anthropogenic zone in Rio de Janeiro state. The data also showed much lower levels of admixture and genetic diversity within the natural hybrid zone than in the anthropogenic zone. Further, the data suggested that the São Francisco River is an important geographic barrier to gene flow in the natural hybrid zone. On the other hand, admixture patterns within the anthropogenic hybrid zone suggested collapse of reproductive barriers, and the formation of a hybrid marmoset swarm. Thus, this work suggested different evolutionary dynamics in anthropogenic vs. natural animal hybrid zones. Restriction Associated DNA sequencing (RADseq) identified a large number of single nucleotide polymorphisms within C. jacchus and C. penicillata genomes. These preliminary data were used to measure intraspecific genomic diversity and interspecific divergence. In the future, RADseq will be used to study genus-wide diversity of Callithrix species, examine past and present marmoset demographic history, and applied to the evolutionary study of marmoset hybridization.

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Created

Date Created
  • 2013