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

1985 ◽  
Vol 51 (1) ◽  
pp. 86-94 ◽  
Author(s):  
R.D. WARD ◽  
K. JANSON
Keyword(s):  
Genetic Analysis ◽  
Sibling Species ◽  
Littorina Saxatilis ◽  
Littorina Arcana

scholarly journals A Quantitative Genetic Analysis of Male Sexual Traits Distinguishing the Sibling Species Drosophila simulans and D. sechellia

Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1683-1699 ◽  
Author(s):  
Stuart J Macdonald ◽  
David B Goldstein
Keyword(s):  
Genetic Analysis ◽  
Sibling Species ◽  
Reproductive Traits ◽  
Drosophila Simulans ◽  
Directional Selection ◽  
Posterior Lobe ◽  
Sex Comb ◽  
Tooth Number ◽  
Comb Tooth ◽  
Shape And Size

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.

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

1996 ◽  
Vol 68 (3) ◽  
pp. 211-220 ◽  
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.

Synchronous Penis Shedding in the Rough Periwinkle, Littorina Arcana

1996 ◽  
Vol 76 (2) ◽  
pp. 539-542 ◽  
Author(s):  
C. Dytham ◽  
J. Grahame ◽  
P. J. Mill
Keyword(s):  
Sibling Species ◽  
East Coast ◽  
Point Scale ◽  
Reproductive Seasonality ◽  
In Captivity ◽  
Littorina Arcana ◽  
Penis Size ◽  
Size And Morphology

Penis size and morphology of an oviparous species of rough winkle Littorina arcana Hannaford Ellis (Gastropoda: Prosobranchia) was studied at Robin Hoods Bay on the English east coast. Monthly collections were made over a two year period from August 1987 to August 1989 and again from May to December 1993. Number of penial glands was recorded and a six point scale was used to quantify penis maturity. Results indicate that male L. arcana shed their penes in summer and regenerate a new one during the following 12–20 weeks. Male L. arcana in captivity shed penes in July but not in November. The significance of penis shedding and the differences in reproductive seasonality between L. arcana and its ovoviviparous sibling species L. saxatilis is discussed.

Patterns of variation in Aat-1 allele frequencies in rough periwinkles (Littorina) suggest similar selection regimes rather than conspecificity

1992 ◽  
Vol 72 (2) ◽  
pp. 499-502 ◽  
Author(s):  
J. Grahame ◽  
P.J. Mill ◽  
M. Double ◽  
S.L. Hull
Keyword(s):  
Gene Diversity ◽  
Enzyme Polymorphism ◽  
Allele Frequency Distribution ◽  
Littorina Saxatilis ◽  
Common Genetic Variation ◽  
Sympatric Populations ◽  
Common Features ◽  
Littorina Arcana ◽  
Polymorphism Data ◽  
Selection Factors

It has been argued by Johannesson & Johannesson (1990b) that the pattern of common genetic variation in Littorina saxatilis (Olivi) and Littorina neglecta Bean indicates gene flow in sympatric populations of these ‘species’. They suggest that L. neglecta is not a good species. We report that a gene diversity analysis of polymorphism in Aat-1 suggests that L. saxatilis and Littorina arcana Hannaford Ellis also show common features in allele frequency distribution. This casts doubt on the argument of Johannesson & Johannesson (1990b) from enzyme polymorphism data on Aat-1 that L. neglecta may simply be an ecotype of L. saxatilis. It seems likely that the similarities are due to operation of the same selection factors on all these species.

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

1991 ◽  
Vol 57 (2) ◽  
pp. 113-122 ◽  
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.

scholarly journals Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina saxatilis

2011 ◽  
Vol 278 (1722) ◽  
pp. 3175-3183 ◽  
Author(s):  
Meredith M. Doellman ◽  
Geoffrey C. Trussell ◽  
John W. Grahame ◽  
Steve V. Vollmer
Keyword(s):  
North Atlantic ◽  
Sequence Data ◽  
Model Organisms ◽  
Phylogeographic Structure ◽  
Littorina Saxatilis ◽  
Mtdna Sequence ◽  
Littorina Arcana ◽  
Mtdna Lineages ◽  
Eastern North Atlantic ◽  
The Last Glacial

Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis , a classic example of marine sympatric speciation. Here, we use mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic for this marker, but is composed of two distinct mtDNA lineages (I and II) that are shared with sister species Littorina arcana and Littorina compressa . Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages originated in the eastern North Atlantic, around the British Isles, at approximately 0.64 Ma. Both lineages are now distributed broadly across the eastern, central and western North Atlantic, and show strong phylogeographic structure among regions. The Iberian Peninsula is genetically distinct, suggesting prolonged isolation from northeastern North Atlantic populations. Western North Atlantic populations of L. saxatilis lineages I and II predate the last glacial maximum and have been isolated from eastern North Atlantic populations since that time. This identification of two distinct, broadly distributed mtDNA lineages further complicates observed patterns of repeated incipient ecological speciation in L. saxatilis , because the sympatric origins of distinct ecotype pairs on eastern North Atlantic shores may be confounded by admixture of divergent lineages.

scholarly journals Genetic analysis of ten polymorphic enzyme loci in Littorina saxatilis (Prosobranchia: Mollusca)

Heredity ◽  
1986 ◽  
Vol 57 (2) ◽  
pp. 233-241 ◽  
Author(s):  
R D Ward ◽  
T Warwick ◽  
A J Knight
Keyword(s):  
Genetic Analysis ◽  
Littorina Saxatilis ◽  
Enzyme Loci

scholarly journals Shell Shape Variation in Littorina Saxatilis and L. Arcana: A Case of Character Displacement?

1989 ◽  
Vol 69 (4) ◽  
pp. 837-855 ◽  
Author(s):  
J. Grahame ◽  
P.J. Mill
Keyword(s):  
Character Displacement ◽  
Shell Morphology ◽  
Shell Shape ◽  
Rocky Shores ◽  
Littorina Saxatilis ◽  
Shape Variation ◽  
Separate Species ◽  
Wide Range ◽  
Littorina Arcana ◽  
Variable Species

It is now well established that there are several species in the group of rough periwinkles inhabiting European rocky shores. The usual consensus agrees on four, namely Littorina saxatilis (Olivi), Littorina arcana Ellis, Littorina nigrolineata Gray and Littorina neglecta Bean. The first two species are particularly difficult to distinguish in the field and have received much attention. Recent work indicates that the ovoviviparous L.saxatilis is a very variable species living in a wide range of habitats (e.g. Janson, 1985) and that, although it is close to the oviparous L. arcana in shell morphology and in genotype, the two are separate species (Ward & Warwick, 1980; Ward & Janson, 1985), and not reproductive morphs of the same species.

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