Limits...
Evolutionary experimentation through hybridization under laboratory condition in Drosophila: evidence for recombinational speciation.

Harini BP, Ramachandra NB - BMC Evol. Biol. (2003)

Bottom Line: Each of these Cytoraces is composed of recombined genomes of the parental races.The results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents.Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces.

View Article: PubMed Central - HTML - PubMed

Affiliation: Drosophila stock centre, Department of Studies in Zoology University of Mysore Manasagangotri Mysore-570 006, India. bpharini@hotmail.com

ABSTRACT

Background: Drosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicans (2n = 6) are a pair of sibling allopatric chromosomal cross-fertile races of the nasuta subgroup of immigrans species group of Drosophila. Interracial hybridization between these two races has given rise to new karyotypic strains called Cytorace 1 and Cytorace 2 (first phase). Further hybridization between Thailand strain of D. n. albomicans and D. n. nasuta of Coorg strain has resulted in the evolution of two more Cytoraces, namely Cytorace 3 and Cytorace 4 (second phase). The third phase Cytoraces (Cytorace 5 to Cytorace 16) have evolved through interracial hybridization among first, second phase Cytoraces along with parental races. Each of these Cytoraces is composed of recombined genomes of the parental races. Here, we have made an attempt to systematically assess the impact of hybridization on karyotypes, morphometric and life history traits in all 16 Cytoraces.

Results: The results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents. Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces.

Conclusion: Thus, the rapid divergence recorded in the chromosomes, karyotypes, body size and fitness traits of Cytoraces exhibit the early event of recombinational raciation / speciation in the evolution of the Cytoraces under laboratory conditions.

Show MeSH

Related in: MedlinePlus

Based on the Duncan's multiple range test (DMR), 18 members of the nasuta-albomicans complex of Drosophila are constructed into clusters and named in the hierarchical form from the lowest to the highest mean wing length. The members belonging to each cluster have insignificant differences. In males, (Fig. 1a), females (Fig. 1b) and both males and females together (Fig. 1c), 8 clusters are made. In males, cluster 1 (C8) with only one member forms an independent cluster, while N, A and C2 emerged as independent (Fig. 1c) as well as overlapping clusters (Fig. 1a and 1b) from the other clusters. All others are with overlapping clusters.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC240057&req=5

Figure 1: Based on the Duncan's multiple range test (DMR), 18 members of the nasuta-albomicans complex of Drosophila are constructed into clusters and named in the hierarchical form from the lowest to the highest mean wing length. The members belonging to each cluster have insignificant differences. In males, (Fig. 1a), females (Fig. 1b) and both males and females together (Fig. 1c), 8 clusters are made. In males, cluster 1 (C8) with only one member forms an independent cluster, while N, A and C2 emerged as independent (Fig. 1c) as well as overlapping clusters (Fig. 1a and 1b) from the other clusters. All others are with overlapping clusters.

Mentions: The females of all 18 members of the nasuta -albomicans complex (NAC) of Drosophila have increased mean wing length (Table 2) and width (Table 3) than males. The analysis of variance test has revealed significant differences in males, females and both males and females with P < 0.001. Based on Dunken's multiple range test (DMRT), D. n. nasuta, D. n. albomicans and the products of first phase of interracial hybridization (Cytorace 1 and Cytorace 2) have increased wing length (Fig. 1) than recently evolved second and third phase Cytoraces, except in males, wherein Cytorace 12 had higher mean values than Cytoraces 1, however, the difference is insignificant. In contrast to this, the mean values of wing width in males, females, and both males and females together majority of the Cytoraces had outside the range of parental races (Fig. 2) indicating that the wing width varies significantly among the Cytoraces.


Evolutionary experimentation through hybridization under laboratory condition in Drosophila: evidence for recombinational speciation.

Harini BP, Ramachandra NB - BMC Evol. Biol. (2003)

Based on the Duncan's multiple range test (DMR), 18 members of the nasuta-albomicans complex of Drosophila are constructed into clusters and named in the hierarchical form from the lowest to the highest mean wing length. The members belonging to each cluster have insignificant differences. In males, (Fig. 1a), females (Fig. 1b) and both males and females together (Fig. 1c), 8 clusters are made. In males, cluster 1 (C8) with only one member forms an independent cluster, while N, A and C2 emerged as independent (Fig. 1c) as well as overlapping clusters (Fig. 1a and 1b) from the other clusters. All others are with overlapping clusters.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC240057&req=5

Figure 1: Based on the Duncan's multiple range test (DMR), 18 members of the nasuta-albomicans complex of Drosophila are constructed into clusters and named in the hierarchical form from the lowest to the highest mean wing length. The members belonging to each cluster have insignificant differences. In males, (Fig. 1a), females (Fig. 1b) and both males and females together (Fig. 1c), 8 clusters are made. In males, cluster 1 (C8) with only one member forms an independent cluster, while N, A and C2 emerged as independent (Fig. 1c) as well as overlapping clusters (Fig. 1a and 1b) from the other clusters. All others are with overlapping clusters.
Mentions: The females of all 18 members of the nasuta -albomicans complex (NAC) of Drosophila have increased mean wing length (Table 2) and width (Table 3) than males. The analysis of variance test has revealed significant differences in males, females and both males and females with P < 0.001. Based on Dunken's multiple range test (DMRT), D. n. nasuta, D. n. albomicans and the products of first phase of interracial hybridization (Cytorace 1 and Cytorace 2) have increased wing length (Fig. 1) than recently evolved second and third phase Cytoraces, except in males, wherein Cytorace 12 had higher mean values than Cytoraces 1, however, the difference is insignificant. In contrast to this, the mean values of wing width in males, females, and both males and females together majority of the Cytoraces had outside the range of parental races (Fig. 2) indicating that the wing width varies significantly among the Cytoraces.

Bottom Line: Each of these Cytoraces is composed of recombined genomes of the parental races.The results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents.Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces.

View Article: PubMed Central - HTML - PubMed

Affiliation: Drosophila stock centre, Department of Studies in Zoology University of Mysore Manasagangotri Mysore-570 006, India. bpharini@hotmail.com

ABSTRACT

Background: Drosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicans (2n = 6) are a pair of sibling allopatric chromosomal cross-fertile races of the nasuta subgroup of immigrans species group of Drosophila. Interracial hybridization between these two races has given rise to new karyotypic strains called Cytorace 1 and Cytorace 2 (first phase). Further hybridization between Thailand strain of D. n. albomicans and D. n. nasuta of Coorg strain has resulted in the evolution of two more Cytoraces, namely Cytorace 3 and Cytorace 4 (second phase). The third phase Cytoraces (Cytorace 5 to Cytorace 16) have evolved through interracial hybridization among first, second phase Cytoraces along with parental races. Each of these Cytoraces is composed of recombined genomes of the parental races. Here, we have made an attempt to systematically assess the impact of hybridization on karyotypes, morphometric and life history traits in all 16 Cytoraces.

Results: The results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents. Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces.

Conclusion: Thus, the rapid divergence recorded in the chromosomes, karyotypes, body size and fitness traits of Cytoraces exhibit the early event of recombinational raciation / speciation in the evolution of the Cytoraces under laboratory conditions.

Show MeSH
Related in: MedlinePlus