Coevolution between a cockroach and its bacterial endosymbiont: a biogeographical perspective

Abstract

Cryptocercus are subsocial, xylophagous cockroaches that live in temperate forests. Like other cockroaches, Cryptocercus harbour endosymbiotic bacteria in their fat bodies. Two species of Cryptocercus occur in the palaearctic, one each in eastern Russia and south-central China. In the USA, there are ¢ve species: one in the north-west and four in the south-east. Little is known about the relationship between the Eurasian and North American Cryptocercus or the causes of the disjunct distribution. Here, a molecular phylogeny for six out of the seven Cryptocercus species and their endosymbionts is inferred in an attempt to understand the evolution and biogeography of the genus. Our analysis showed that the North American Cryptocercus are monophyletic, suggesting that a single colonization event was followed by vicariance. There was complete concordance between the host and endosymbiont phylogenetic trees. Divergence estimates based on endosymbiont DNA sequences suggested that the palaearctic and nearctic Cryptocercus diverged 70^115 million years (Myr) ago and the eastern-and western-USA species diverged 53^88 Myr ago. These divergence estimates were correlated with biogeographical events, and a hypothesis is presented to explain the current distribution of Cryptocercus. Our ¢ndings suggest that Cryptocercus has had a long evolutionary history, dating back to the Jurassic.

Nitrogen recycling and nutritional provisioning byBlattabacterium, the cockroach endosymbiont

“…2). These results are consistent with 16S rRNA gene analyses that included more taxa (19,21,22). Many genes, including some expected to enable metabolic plasticity, are eliminated from obligate endosymbiont genomes (Table S1), leaving genes essential to maintaining the host-symbiont lifestyle (i.e., amino acid biosynthesis) (48).…”

“…Blattabacterium appears to have infected the common ancestor of cockroaches and termites Ͼ140 Mya (21,22). It has been maintained in all cockroaches except the cave-dwelling Nocticola and lost in all termites except the basal species, Mastotermes darwiniensis (17,22).…”

‘Candidatus Streptomyces philanthi’, an endosymbiotic streptomycete in the antennae of Philanthus digger wasps

“…The high degree of 16S rRNA gene sequence similarity among Philanthus endosymbionts suggests that they are transmitted vertically from mother to offspring, as has been described for many other endosymbiotic bacteria (Aksoy et al, 1997;Clark et al, 2000Clark et al, , 2001Ishikawa, 2003;Sauer et al, 2000). Alternatively, the bacteria may be taken up from the environment with certain mechanisms preventing the uptake of non-symbiotic bacteria, a transmission route that has been demonstrated for the symbionts of the squid Euprymna scolopes (McFallNgai & Ruby, 1991;Nishiguchi, 2002;Nyholm et al, 2000;Nyholm & McFall-Ngai, 2004).…”

Evolutionary trend of the small subunit nuclear ribosomal DNAs (SSU rDNAs) of wood-feedingCryptocercuscockroaches (Blattaria:Cryptocercus)

“…Thus, the causes and dynamics that shape their present-day distribution have been the subject of vigorous discussion over the last decade, associated with their taxonomic status as well as phylogeography (Burnside et al 1999;Nalepa & Bandi 1999;Grandcolas 1999aGrandcolas , 1999bClark et al 2001;Nalepa et al 2002;Park et al 2004). …”

“…In addition, to assess inter-and/or intra-specific genetic variation, or to better understand the spatiotemporal history of the geographic isolates, studies using mitochondrial DNA markers have been conducted extensively for Cryptocercus species, especially for the Nearctic cockroaches (Burnside et al 1999;Clark et al 2001;. In karyotype analysis, four variants (male 2n037, 39, 43, 45) were found in C. punctulatus species complex in the southern Appalachian Mountains of eastern North America, and none of the variants occurs in the same locality, displaying different distribution range (Burnside et al 1999;Nalepa et al 2002).…”