Cryptic diversity in coastal Australasia: a morphological and mitonuclear genetic analysis of habitat-forming sibling species

Abstract A quantitative trait locus (QTL) genetic analysis of morphological and reproductive traits distinguishing the sibling species Drosophila simulans and D. sechellia was carried out in a backcross design, using 38 markers with an average spacing of 8.4 cM. The direction of QTL effects for the size of the posterior lobe was consistent across the identified QTL, indicating directional selection for this trait. Directional selection also appears to have acted on testis length, indicating that sexual selection may have influenced many reproductive traits, although other forms of directional selection cannot be ruled out. Sex comb tooth number exhibited high levels of variation both within and among isofemale lines and showed no evidence for directional selection and, therefore, may not have been involved in the early speciation process. A database search for genes associated with significant QTL revealed a set of candidate loci for posterior lobe shape and size, sex comb tooth number, testis length, tibia length, and hybrid male fertility. In particular, decapentaplegic (dpp), a gene known to influence the genital arch, was found to be associated with the largest LOD peak for posterior lobe shape and size.

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Genetics of sexual isolation in male hybrids of Drosophila simulans and D. mauritiana

Genetics Research ◽

10.1017/s0016672300034182 ◽

1996 ◽

Vol 68 (3) ◽

pp. 211-220 ◽

Cited By ~ 23

Author(s):

Jerry A. Coyne

Keyword(s):

Genetic Analysis ◽

Y Chromosome ◽

Sibling Species ◽

Previous Analysis ◽

Sexual Isolation ◽

Drosophila Simulans

SummarySexual isolation between the sibling species D. simulans and D. mauritiana is due largely to the rejection of D. simulans males by D. mauritiana females. Genetic analysis shows that genes on the X and third chromosomes contribute to the differences between males causing sexual isolation, while the Y chromosome, second chromosome and cytoplasm have no effect. These chromosome effects differ from those observed in a previous analysis of sexual isolation in hybrid females, implying that different genes cause sexual isolation in the two sexes.

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A GENETIC ANALYSIS OF SYMPATRIC SUBPOPULATIONS OF THE SIBLING SPECIES LITTORINA SAXATILIS (OLIVI) AND LITTORINA ARCANA HANNAFORD ELLIS

Journal of Molluscan Studies ◽

10.1093/oxfordjournals.mollus.a065888 ◽

1985 ◽

Vol 51 (1) ◽

pp. 86-94 ◽

Cited By ~ 31

Author(s):

R.D. WARD ◽

K. JANSON

Keyword(s):

Genetic Analysis ◽

Sibling Species ◽

Littorina Saxatilis ◽

Littorina Arcana

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Genetics of morphological differences and hybrid sterility between Drosophila sechellia and its relatives

Genetics Research ◽

10.1017/s0016672300029177 ◽

1991 ◽

Vol 57 (2) ◽

pp. 113-122 ◽

Cited By ~ 50

Author(s):

Jerry A. Coyne ◽

John Rux ◽

Jean R. David

Keyword(s):

Genetic Analysis ◽

X Chromosome ◽

Sibling Species ◽

Male Genitalia ◽

Hybrid Sterility ◽

Drosophila Sechellia ◽

Ovariole Number ◽

The Difference ◽

Male Hybrid ◽

Morphological Differences

SummaryWe conducted classical genetic analysis of the difference in male genitalia and hybrid sterility between the island-dwelling sibling species Drosophila sechellia and D. mauritiana. At least two loci (one on each autosome) are responsible for the genital difference, with the X chromosome having no significant effect. In contrast, male hybrid sterility is caused by at least four gene loci distributed among all major chromosomes, with those on the X chromosome having the largest effect.We also show that the large difference in ovariole number between D. sechellia and its mainland relative D. simulans is due to at least two gene substitutions, one on each major autosome. The X and the left arm of the second chromosome, however, have no significant effect on the character. This implies that the evolution of reduced ovariole number involved relatively few gene substitutions.These results extend previous findings that morphological differences between Drosophila species are caused by genes distributed among all chromosomes, while hybrid sterility and inviability are due primarily to X-linked genes. Because strong X-effects on male sterility have been found in all three pairwise hybridizations among D. simulans, D. sechellia and D. mauritiana, these effects must have evolved at least twice independently.

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