Presentation Title

Genetic Structure of the Black Legged Tick, Ixodes scapularis

Location

Atrium

Session Format

Poster Presentation

Research Area Topic:

MBI - Molecular Biology Initiative

Co-Presenters, Co- Authors, Co-Researchers, Mentors, or Faculty Advisors

Cynthia Chan, University of Georgia Athens, Athens, GA, Isis M. Kuczaj, Michigan State University, East Lansing, MI and Lorenza Beati, Georgia Southern University, Statesboro, GA.

Abstract

The black legged tick, Ixodes scapularis, is the main vector of Borrelia burgdorferi, the etiological agent of Lyme disease. An interesting and significant difference in the prevalence of Lyme disease in humans is observed between the North and the South of the U.S.; in the six year period between 1992 and 1998, 10 Northern States (above 36 ° 31’ N) accounted for 92% of reported Lyme disease and in 2013, 14 Northern States accounted for 95% of the human reported cases of Lyme disease. Although the genetic structure of I. scapularis has already been the subject of several studies, none of the published information combines the analysis of maternally inherited (mitochondrial) and bi-parentally inherited (nuclear and microsatellite) markers on the same set of ticks. In addition, the geographical distribution of the analyzed samples was often partial and did not cover the whole range of I. scapularis. We collected a sample of 350 ticks from 17 states. The small ribosomal subunit (12SrRNA), the control region (d-loop), and the ribosomal internal transcribed spacer regions (ITS2) of each tick were sequenced and compared in order to establish if mitochondrial and nuclear gene sequences provide the same information. In addition, 9 microsatellite markers were genotyped. Our preliminary data showed that I. scapularis resolved into 5 mitochondrial clades, which can be tracked back to biogeographical events during Quaternary. The ITS2 sequences are highly conserved and do not differentiate the same groups, which suggests a recent dispersal of this tick species. The microsatellite markers corroborate nuclear data by showing little geographical differentiation, persistent gene flow between populations, and no support for the mitochondrial clade subdivision. In summary, I. scapularis is a monophyletic group that established itself after the glaciation events of the Quaternary period with mitochondrial data supporting five distinct linages and microsatellite supporting interbreeding between populations.

Keywords

Ixodes scapularis, Genetics, Borrelia, Systematics

Presentation Type and Release Option

Presentation (Open Access)

Start Date

4-24-2015 2:45 PM

End Date

4-24-2015 4:00 PM

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Apr 24th, 2:45 PM Apr 24th, 4:00 PM

Genetic Structure of the Black Legged Tick, Ixodes scapularis

Atrium

The black legged tick, Ixodes scapularis, is the main vector of Borrelia burgdorferi, the etiological agent of Lyme disease. An interesting and significant difference in the prevalence of Lyme disease in humans is observed between the North and the South of the U.S.; in the six year period between 1992 and 1998, 10 Northern States (above 36 ° 31’ N) accounted for 92% of reported Lyme disease and in 2013, 14 Northern States accounted for 95% of the human reported cases of Lyme disease. Although the genetic structure of I. scapularis has already been the subject of several studies, none of the published information combines the analysis of maternally inherited (mitochondrial) and bi-parentally inherited (nuclear and microsatellite) markers on the same set of ticks. In addition, the geographical distribution of the analyzed samples was often partial and did not cover the whole range of I. scapularis. We collected a sample of 350 ticks from 17 states. The small ribosomal subunit (12SrRNA), the control region (d-loop), and the ribosomal internal transcribed spacer regions (ITS2) of each tick were sequenced and compared in order to establish if mitochondrial and nuclear gene sequences provide the same information. In addition, 9 microsatellite markers were genotyped. Our preliminary data showed that I. scapularis resolved into 5 mitochondrial clades, which can be tracked back to biogeographical events during Quaternary. The ITS2 sequences are highly conserved and do not differentiate the same groups, which suggests a recent dispersal of this tick species. The microsatellite markers corroborate nuclear data by showing little geographical differentiation, persistent gene flow between populations, and no support for the mitochondrial clade subdivision. In summary, I. scapularis is a monophyletic group that established itself after the glaciation events of the Quaternary period with mitochondrial data supporting five distinct linages and microsatellite supporting interbreeding between populations.