Distortional meiotic segregation of a supernumerary chromosome producing differential frequencies in the sexes in the short-horned grasshopper Phaulacridium vittatum

Increased B chromosome frequency and absence of drive in the fish Prochilodus lineatus

“…Studies on the temporal stability of B chromosome polymorphisms have shown that some populations reach a stable frequency over periods from 6 to 9 years (Hewitt & John, 1967;Jackson & Cheung, 1967;Kayano et al, 1970). Some populations of mealy bugs (Nur, 1966) and rye (Jones & Rees, 1982) showed an increase in the number of B chromosomes over some generations, similar to that observed in P lineatus from the Mogi-Guacu river.…”

Cytogenetic studies on natural populations of Acrida Lata I. Local variation in the frequency of B-chromosomes

“…In Pseudococcus obscurus on the other hand B's are less frequent in the males than in the females (Nur, 1966(Nur, , 1968. Jackson and Cheung (1967) find that in Phaulacridium vittatum, B chromosomes segregate preferentially from the X chromosome in primary spermatocytes and on this basis suggest a differential frequency of B's may well occur between the sexes in this species. This suggestion has not been tested by observation as yet.…”

“…Kimura and Kayano, 1961;Nur, 1966;Hewitt and John, 1967), equilibrium frequencies of B's have been found in several cases, at least on a short-term basis. This applies, for example, to Aiolopus species B (Ray-Chaudhury and Guha, 1955), Pseudococcus obscurus (Nur, 1966), Phaulacridium vittatum (Jackson and Cheung, 1967), Lilium callosum (Kimura and Kayano, 1961), and Myrmeleotettix maculatus (Hewitt and John, 1967). In the present study no A. lata population lost its B chromosomes during the period of observation.…”

“…Recently, Jackson and Cheung (1967) reported stable frequencies of B's over 9 years in a population of Phaulacridium vittatum.…”

Population Cytology of the Genus Phaulacridium VI. Seasonal Changes in the Frequency of the B Chromosome in a Population of Ph. vittatum

“…This would appear to be especially true in the Acrididae (Hewitt 1973;Robinson and Hewitt 1976). Whilst much effort has been spent investigating the year-to-year stability of B chromosome polymorphisms in different populations of grasshoppers (Jackson and Cheung 1967;Kayano et al 1970;Westerman 1975a; Robinson and Hewitt 1976), as yet little has been done to follow in detail the frequency of B-containing individuals within a particular season in order to ascertain any possible selective advantage or disadvantage. In one such study on the British grasshopper Myrmeleotettix maculatus, Hewitt (1974) and Robinson and Hewitt (1976) have shown that the apparent constancy of B frequency in a popUlation over a period of years, as estimated from annual samples of adult males, may well mask significant short-term fluctuations in B frequency within that population.…”