Abstract
Nowadays a number of endemic mosquito species are known to possess vector abilities for various diseases, as e.g. the sibling species Culex pipiens and Culex torrentium. Due to their morphological similarity, ecology, distribution and vector abilities, knowledge about these species' population structure is essential. Culicidae from 25 different sampling sites were collected from March till October 2012. All analyses were performed with aligned cox1 sequences with a total length of 658 bp. Population structure as well as distribution patterns of both species were analysed using molecular methods and different statistical tests like distance based redundancy analysis (dbDRA), analysis of molecular variances (AMOVA) or McDonald & Kreitman test and Tajima's D. Within both species, we could show a genetic variability among the cox1 fragment. The construction of haplotype networks revealed one dominating haplotype for Cx. pipiens, widely distributed within Germany and a more homogeneous pattern for Cx. torrentium. The low genetic differences within Cx. pipiens could be a result of an infection with Wolbachia which can induce a sweep through populations by passively taking the also maternally inherited mtDNA through the population, thereby reducing the mitochondrial diversity as an outcome of reproductive incompatibility. Pairwise population genetic differentiation (FST) ranged significantly from moderate to very great between populations of Cx. pipiens and Cx. torrentium. Analyses of molecular variances revealed for both species that the main genetic variability exists within the populations (Cx. pipiens [88.38%]; Cx. torrentium [66.54%]). Based on a distance based redundancy analysis geographical origin explained a small but significant part of the species' genetic variation. Overall, the results confirm that Cx. pipiens and Cx. torrentium underlie different factors regarding their mitochondrial differentiation, which could be a result of endosymbiosis, dispersal between nearly located populations or human introduction.
Highlights
Since the late 19th century, mosquitoes are known as vectors for various diseases as malaria, dengue, yellow or Chikungunya fever [1,2]
Culex torrentium was thought to utilize more natural breeding sites, whereas in this study larvae of both species were often found sympatric in artificial water bodies
Different factors underlie the mitochondrial differentiation in both species
Summary
Since the late 19th century, mosquitoes are known as vectors for various diseases as malaria, dengue, yellow or Chikungunya fever [1,2]. The spread is encouraged by the increasing international travel and global freight transportation which have direct influence on the introduction and establishment of mosquito-associated viruses from other countries to Europe [4,5,6]. Many studies deal with invasive species such as Aedes aegypti, Aedes albopictus or Ochlerotatus japonicus, which have been introduced and established in different countries. Numerous indigenous mosquito species are known to be potential carriers of diseases such as Sindbis virus, Ockelbo virus, Usutu virus, Batai virus, West-Nile virus or even malaria [2,7,8,9,10,11]
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