Publication Date

2007

Document Type

Thesis

Committee Members

Dan Krane (Advisor)

Degree Name

Master of Science (MS)

Abstract

Of all major aquatic invertebrate groups, members of family Chironomidae are most abundant and show a wide range of habitat preferences. The importance of correct identification of Chironomids has been realized in many bioassessment studies mainly because of their worldwide distribution, substrate specificities and predictable responses to various pollutants in the water sources. This study establishes that the sequence data from the Intergenic Spacer Regions (ITS) of ribosomal DNA could be used as molecular markers to distinguish between different Chironomidae species and also to identify them. The need to use molecular approaches, to identify various Chironomidae species, comes from the fact that the rate of misidentifications is fairly high when morphological features are used. A difference of six nucleotides in the sequence data of Chironomus tentans from North America and Europe suggest a low intraspecific variation. A detailed analysis of the ITS-1 and ITS-2 sequence data from seven new species of Chironomids (Thienemanniella xena, Xylatopus par, Tribelos fuscicorne, Robackia demeijerei, Tribelos jucundum, Polypedilum aviceps and Chironomus tentans) along with 15 species obtained from Genbank considered in this study shows a high amount of interspecific variations and also that the European species tend to cluster close to each other when compared to North American ones. The high bootstrap values and short intercluster branches, depicted in the phylogram, might suggest presence of various clusters and rapid divergence of species, respectively within the genus Chironomus. Such phylogenetic analysis could also provide more information on the genetic relatedness among different species.

Page Count

122

Department or Program

Department of Biological Sciences

Year Degree Awarded

2007

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