title: The muscle of lawrence in Drosophila: a case of repeated evolutionary loss.
abstract: The muscle of Lawrence (MOL) is a bilaterally symmetrical muscle spanning the tergite of the fifth abdominal segment of adult male Drosophila melanogaster. It is not, however, a general feature of male-specific development within the subfamily Drosophilinae. Of 95 species surveyed within this subfamily, 67 exist with no MOL at all. By drawing comparisons with published cladograms of species relatedness, three conclusions regarding the evolutionary history of the MOL are made: (i) The MOL predates the major radiations of the genus Drosophila, given its presence in earlier-branching Chymomyza and Scaptodrosophila; the MOL has been subsequently excluded in at least one present species of each of these two primitive genera. (ii) Within the genus Drosophila the MOL is present sporadically in the radiation of the subgenus Sophophora, showing repetitive loss even in very close evolutionary lineages. (iii) The MOL may have been entirely excluded from the prolific radiation of the subgenus Drosophila. Thus the MOL shows a uniquely incongruous pattern of presence or absence relative to accepted drosophilid phylogeny.
authors.affiliation: Department of Biological Sciences, California State University, Hayward, CA 94542, USA. dgailey@csuhayward.edu
authors.forename: D A
authors.initials: DA
authors.lastname: Gailey
authors.forename: S
authors.initials: S
authors.lastname: Ohshima
authors.forename: S J
authors.initials: SJ
authors.lastname: Santiago
authors.forename: J M
authors.initials: JM
authors.lastname: Montez
authors.forename: A R
authors.initials: AR
authors.lastname: Arellano
authors.forename: J
authors.initials: J
authors.lastname: Robillo
authors.forename: C A
authors.initials: CA
authors.lastname: Villarimo
authors.forename: L
authors.initials: L
authors.lastname: Roberts
authors.forename: E
authors.initials: E
authors.lastname: Fine
authors.forename: A
authors.initials: A
authors.lastname: Villella
authors.forename: J C
authors.initials: JC
authors.lastname: Hall
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004175:Diptera / Q000033:anatomy & histology* / Q000145:classification; D004330:Drosophila / Q000033:anatomy & histology* / Q000145:classification; D008297:Male; D009132:Muscles; D010641:Phenotype; D010802:Phylogeny