Geographical Barriers Impeded the Spread of a Parasitic Chromosome

Abstract

Parasitic supernumerary (B) chromosomes show high capability to spread across populations. But the existence of abrupt discontinuities in their distribution demands an explanation. The grasshopper Eyprepocnemis plorans plorans harbour supernumerary chromosomes in all natural populations hitherto analyzed from the Circum-Mediterranean region, with the single exception of the headwaters of the Iberian Segura River and several of its tributaries. To ascertain the causes of this distribution pattern, we analyze here the genetic structure of five natural populations collected in this zone (two +B and three -B), by means of ISSR markers. We found significant population structure, with two kinds of populations coinciding with +B and -B ones, separated by strong barriers to gene flow. This gives strong support to the hypothesis that the non-B populations precede B origin, and that B-carrying individuals from coastal zones have been able to colonize upstream areas, until geographical barriers (usually narrow canyons and arid areas surrounding them) impeded their advance.

Genetic diversity in the camellia weevil, Curculio chinensis Chevrolat (Coleptera: Curculionidae) and inferences for the impact of host plant and human activity

“…; Manrique‐Poyato et al . ), mutations between adjacent haplotypes were more frequent in the present study and ranged from one step mutation to 65 (Fig. ).…”

Wide dispersion of B chromosomes in Rhammatocerus brasiliensis (Orthoptera, Acrididae)

“…For this species, the altitude of the analyzed populations did not seem to influence the frequency of B chromosomes either. This observation differs from that of Manrique-Poyato et al (2015), who stated that individuals with B chromosomes have low tolerance to high-altitude environments as a result of delay in meiosis due to the presence of B chromosomes that may negatively select the host (Hewitt and East, 1978;Harvey and Hewitt, 1979).…”

“…Regarding Neotropical species, the distribution of B chromosomes in natural grasshopper populations has not been analyzed under consideration of the genetic structure of the populations, and such studies have only been performed in Palearctic grasshoppers (Keller et al, 2013;Manrique-Poyato et al, 2013a,b, 2015. This kind of approach allows estimating the gene flow among individuals within and between populations, which may be a parameter directly related to the dispersion or isolation of B chromosomes (Manrique-Poyato et al, 2015).…”

Origin of B chromosomes in Characidium alipioi (Characiformes, Crenuchidae) and its relationship with supernumerary chromosomes in other Characidium species

“…The presence of these elements in only certain populations was observed in other species of the genus Characidium such as Characidium zebra , Characidium pterostictum and Characidium gomesi ( Pansonato-Alves et al 2014 ). Our data does not allow to conclude about the dynamics or relationship of these chromosomes between populations; however, at least two mechanisms, which are based on the findings of two model organisms have been proposed to be involved in the absence of B chromosomes in certain populations: geographical barriers that limit the spread of individuals with these elements in Eyprepocnemis plorans Charpentier, 1825 ( Cabrero et al 1997 , Manrique-Poyato et al 2015 ) and the close relationship between temperature and rainfall factors that could influence the variations in the presence of B chromosomes, as observed in Myrmeleotettix maculatus Thunberg, 1815 ( Hewitt and John 1967 ; Hewitt and Ruscoe 1971 ).…”