Understanding chromosomal evolution and its role in the speciation process.

Delena cancerides is the most chromosomally diverse of any species studied to date. Some populations carry the ancestral karyotype of 43 telocentric chromosomes in the male, while others have undergone wholesale chromosomal fusion, resulting in a karyotype of 22 chromosomes. The combination of chromosome fusions is variable, and at least 14 different chromosomal races, with different fusion combinations have been identified. Studies of natural and lab populations indicate that hybridisation between a number of the races occurs freely, and hybrids are fertile. This variation makes D. cancerides and excellent model for the study of chromosomal meiotic behaviour and chromosomal evolution.

Relevant references

• Rowell D.M. 1990 Complex fusion heterozygosity in Delena cancerides (Araneae : Sparassidae) : An alternative to speciation by monobrachial homology. Genetica 80 : 139 - 157
• Rowell D.M. 1991 Chromosomal fusion and meiotic behaviour in Delena cancerides (Araneae : Sparassidae) I. Pairing and X-chromosome segregation. Genome 34 : 561 - 566
• Rowell D.M. 1991 Chromosomal fusion and meiotic behaviour in Delena cancerides (Araneae : Sparassidae) II. Chiasma position and its implications for speciation. Genome 34 : 567 - 573
• Sharp H.E. & Rowell D.M. (2007) Unprecedented chromosomal diversity and behaviour modify linkage patterns and speciation processes: structural heterozygosity in an Australian spider. J. Evol. Biol. 20: 2427 - 2439.