Drosophila (Sophophora) sechellia

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General Information
Taxonomic Name	Drosophila (Sophophora) sechellia. (Tsacas and Baechli, 1981). Revue fr. Ent. NS 3(4): 146--150. pg.146
Location of types
Fossil	Not known as fossil species
NCBI ID	taxon:7238
FlyBase ID	FBsp00000217
FlyBase Abbreviation	Dsec
Notes
	Drosophila sechellia is known only from some of the islands of the Seychelles archipelago (Cousin, Praslin, and Frigate islands). Here, it breeds on the fallen fruits of the maritime rubiaceous shrub Morinda citrifolia. This is odd, because this shrub appears to be a recent introduction to these islands (for discussion, see Lemeunier and Ashburner, 1984). Drosophila sechellia is rather more difficult to culture in the laboratory than either Drosophila simulans or Drosophila mauritiana (see Louis and David, 1986). The hybridization of Drosophila sechellia and Drosophila melanogaster is similar to that of Drosophila simulans and Drosophila melanogaster. The natural host plant of Drosophila sechellia, M. citrifolia, contains chemicals that are toxic to other species in the melanogaster species subgroup (R'kha et al., 1991); chief among these is octanoic acid, although other compounds, particular n-caproic acid, contribute to toxicity (Legal et al., 1992; Legal et al., 1994; Farine et al., 1996). These chemicals promote oviposition in Drosophila sechellia, but inhibit oviposition in its sibling species (Amlou et al., 1998). The LC50 of octanoic acid to larvae of Drosophila melanogaster is 0.40%, to larvae of Drosophila sechellia it is 4.15% (Amlou et al., 1998). The genetic basis of the resistance of Drosophila sechellia to these toxins is relatively simple, with a few semidominant "resistant" alleles responsible for adult resistance and, possibly, a subset of these responsible for larval resistance (Jones, 1998; Jones, 2001). Drosophila sechellia adults are attracted to, but the adults of its relatives repelled by, n-caproic acid (Higa and Fuyama, 1993). The first instar larvae of Drosophila sechellia differ from those of its siblings in that the posterior region of the anterior compartment of the abdominal tergites lack the carpet of fine hairs characteristic of its sibling species; this is due to a change in expression of the shaven-baby gene (Sucena and Stern, 2000). The Y chromosome of Drosophila sechellia, like that of Drosophila simulans (but not of the other species of the subgroup) lacks rDNA genes (Lohe and Roberts, 2000).
Chromosomes
Mitotic
	Number Karyotype Notes References Karyotype
Polytene chromosomes
Maps	Muller Element Chromosome/Arm Click on a chromosome or arm to view a map X 2L 2R 3L 3R 4
Polytene chromosome references
	Lemeunier and Ashburner, 1984, Chromosoma 89(5): 343--351 Relationships within the melanogaster species subgroup of the genus Drosophila (Sophophora). [FBrf0040524]
DNA Content
Male Female Mixed Method Notes References 176mb 167mb - cytophotometry Normalized to a 175mb genome for D. melanogaster. (Ashburner et al., 2005)
Reproductive System

Sperm Length
	Length Notes References 1.649mm (Joly et al., 1991) 1.649+/-0.008mm (Joly et al., 1989)
Images of the Life Cycle
	Male Female
Stocks (Publicly Available)
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Synonyms & Other Names
Synonyms

Lapsus

Nomen nudum

Nomen dubium

Preoccupied

References
	Amlou et al., 1998, Behav. Genet. 28(6): 455--464 Genetic analysis of Drosophila sechellia specialization: oviposition behavior toward the major aliphatic acids of its host plant. [FBrf0106143] Amlou et al., 1998, Hereditas 129(1): 7--14 Larval tolerance in the Drosophila melanogaster species complex toward the two toxic acids of the D. sechellia host plant. [FBrf0105768] Ashburner et al., 2005, Drosophila: a laboratory handbook. Second edition. Drosophila: a laboratory handbook. Second edition. [FBrf0202435] Farine et al., 1996, Phytochemistry 41(2): 433--438 Volatile components of ripe fruits of Morinda citrifolia and their effects on Drosophila. [FBrf0086399] Higa and Fuyama, 1993, Genetica 88(2-3): 129--136 Genetics of food preference in Drosophila sechellia. [FBrf0064504] Joly et al., 1989, Genetique Sel. Evol. 21(3): 283--293 Variation of sperm length and heteromorphism in Drosophilid species. [FBrf0049859] Joly et al., 1991, D. I. S. 70: 104--108 Sperm length diversity in Drosophilidae. [FBrf0053516] Jones, 1998, Genetics 149(4): 1899--1908 The genetic basis of Drosophila sechellia's resistance to a host plant toxin. [FBrf0103289] Jones, 2001, Genet. Res. 78(3): 225--233 The genetic basis of larval resistance to a host plant toxin in Drosophila sechellia. [FBrf0144885] Legal et al., 1992, Chemoecology 3(3-4): 125--129 Toxicity and attraction effects produced by Morinda citrifolia fruits on the Drosophila melanogaster complex of species. [FBrf0080202] Legal et al., 1994, J. chem. Ecol. 20(8): 1931--1943 Molecular basis of Morinda citrifolia, L.: Toxicity on Drosophila. [FBrf0076860] Lemeunier and Ashburner, 1984, Chromosoma 89(5): 343--351 Relationships within the melanogaster species subgroup of the genus Drosophila (Sophophora). [FBrf0040524] Lohe and Roberts, 2000, Genetica 109(1-2): 125--130 Evolution of DNA in heterochromatin: the Drosophila melanogaster sibling species subgroup as a resource. [FBrf0135791] Louis and David, 1986, Acta Oecol., Oecol. gen. 7(3): 215--229 Ecological specialization in the Drosophila melanogaster species subgroup: A case study of Drosophila sechellia. [FBrf0043684] McBride, 2007, Proc. Natl. Acad. Sci. USA: Rapid evolution of smell and taste receptor genes during host specialization in Drosophila sechellia. [FBrf0193312] R'kha et al., 1991, Proc. Natl. Acad. Sci. USA 88(5): 1835--1839 Host-plant specialization in the Drosophila melanogaster species complex: a physiological, behavioral, and genetical analysis. [FBrf0054952] Sucena and Stern, 2000, Proc. Natl. Acad. Sci. USA 97(9): 4530--4534 Special feature: divergence of larval morphology between Drosophila sechellia and its sibling species caused by cis-regulatory evolution of ovo/shaven-baby. [FBrf0127340] Tsacas and Baechli, 1981, Revue fr. Ent. NS 3(4): 146--150 Drosophila sechellia, n.sp., huitieme espece du sous-goupe melanogaster des Iles Sechelles [Diptera, Drosophilidae]. [FBrf0037299]