Sex chromosome translocation and speciation : a Drosophila genetic model

Although exceptions may be readily identified, two generalizations concerning genetic differences among species may be drawn from the available allozyme and chromosome data. First, structural gene differences among species vary widely. In many cases, species pairs do not differ more than intraspecific populations. This suggests that either very few or no gene substitutions are required to produce barriers to reproduction (Avise 1976). Second, chromosome form and/or number differs among even closely related species (White 1963; 1978; Fredga 1977; Wright 1970). Many of the observed chromosomal differences involve translocational rearrangements; these produce severe fitness depression in heterozygotes and were, thus, long considered unlikely candidates for the fixation required of genetic changes leading to speciation (Wright 1977). Nonetheless, the fact that species differences are frequently translocational argues convincingly for their fixation despite prejudices to the contrary. Haldane's rule states that in the F of interspecific crosses, the heterogametic sex is absent or sterile in the preponderance of cases (Haldane 1932). This rule definitely applies in the genus Dr°sophila (Ehrman 1962). Sex chromosome translocations do not impose a fitness depression as severe as that imposed by autosomal translocations, and X-Y translocations may account for Haldane's rule (Haldane 1932). Consequently a study of the fit ness parameters of an X·yL and a yS chromosome in Drosophila melanogaster populations was initiated by Tracey (1972). Preliminary results suggested that x.yL//YSmales enjoyed a mating advantage with X·yL//X·yL females, that this advantage was frequency dependent, that the translocation produced sexual isolation and that interactions between the yL, yS and a yellow marker contributed to the observed isolation (Tracey and Espinet 1976; Espinet and Tracey 1976). Encouraged by the results of these prelimimary studies, further experiments were performed to clarify the genetic nature of the observed sexual isolation, S the reality of the y frequency dependent fitness .and the behavioural changes, if any, produced by the translocation. The results of this work are reported herein. Although the marker genes used in earlier studies, sparkling poliert an d yellow have both been found to affect activity,but only yellow effects asymmetric sexual isolation. In addition yellow effects isolation through an interaction with the T(X-y) chromosomes, yS also effects isolation, and translocational strains are isolated from those of normal karyotype in the absence of marker gene differences. When yS chromosomes are in competition with y chromosomes on an X.yL background, yS males are at a distinct advantage only when their frequency is less than 97%. The sex chromosome translocation alters the normal courtship pattern by the incorporation of circling between vibration and licking in the male repertoire. Finally a model of speciation base on the fixation of this sex chromosome translocation in a geographically isolated gene pool is proposed.

Viability interactions between the left and right arms of the second chromosome of Drosophila melanogaster

Inter and intrachromosomal viability interactions have been detected in a few experimental studies. Computer simulations and analytical models have led to postulation of nonadditivity of gene action. This study reports evidence of strong nonadditive interactions between the arms of the metacentric second chromosome of Drosophila melanogaster. Mean viability for 40 homozygous lines of the second chromosomes was 0.720+0.265 • Mean viability for 40 half homozygous second chromosomes was 0.928!O.)10 • Significant heterogeneity among and within lines was found in both groups of chromosomes, as well as a highly significant viability difference between the two groups. Comparison of observed viabilities with the expected values, according to the theories of additive and multi - plicative gene action. was made for both groups. Highly significant departures from the expected values were found for over 90% of the lines in both groups of chromosomes, for both additive and multiplicative models of gene action.

Second Welland Canal - Book 2, Survey Map 5 - Locks 16, 17 and 18 in Grantham

Survey map of the Second Welland Canal created by the Welland Canal Company showing the Grantham Township at Merritton. Identified structures associated with the Canal include Locks 15, 16, 17, and 18, and the towing path. The surveyors' measurements and notes can be seen in red and black ink and pencil. Local area landmarks are also identified and include streets and roads (ex. Hartzel Road and Macadamized Road), Lybster Cotton Mill, St. Catharines Paper Mill, J. Brown Cotton Mills, hydraulic race, a pond, several barns, and a number of structures (likely houses or cabins) belonging to: J. McNamara, M. Moran, A. Delany, T. Joyce, J. Delany, C. Blake, F. Weaver, W. Leeson, and Mrs. Aikins. Properties of note are: Concession 10 Lots 11 and 12. A number of reserved properties exist and are outlined in blue. They include three reserved properties for lock lots, and one large property reserved for a quarry.

Second Welland Canal - Book 2, Survey Map 17 - Deep Cut and Port Robinson

Survey map of the Second Welland Canal created by the Welland Canal Company showing the canal at Port Robinson. Identified structures and features associated with the Canal include the Deep Cut, Old Channel of Canal, and the towing path. The surveyors' measurements and notes can be seen in red and black ink and pencil. Local area landmarks are also identified and include streets and roads (ex. Road to Port Allanburg), the Spoil Bank, an island, several bridges, and a church. Several unidentified structures are present but not labeled. Properties and property owners of note are: Lots 202, 203, and 204. Lot 203 is divided into several properties labeled A - J. Owners of these properties include James McCoppen, John Coulter, James Griffith, John C. Jordan, W. Hendershot, John Greer, Charles Richards, C. Stuart, and S. D. Woodruff. Other property owners include D. McFarland.

Second Welland Canal - Book 3, Survey Map 17 - Through Humberstone

Survey map of the Second Welland Canal created by the Welland Canal Company showing the area through Humberstone. Identified structures associated with the Canal include Spoil Banks, Towing Path, Back Ditches and Culvert. Surveyor measurements and notes can be seen in red and black ink and pencil. Local area landmarks include Lyons Creek and Big Elm Tree. Roads running parallel to Canal include the south Road Allowance and the Road to Port Colborne. Roads running perpendicular to Canal include Road Allowance between the 3rd and 4th Concessions, Road Allowance between the 4th and 5th Concessions. Properties are noted as Lot No. 28, 4th Concession, Lot No. 27, 4th Concession and Lot No. 26, 4th Concession."Humberstone"

New-England Palladium Vol. XLII No. 49- December 17, 1813

A four page, semi-weekly paper that was published from 1803 to 1814.

Letter - Frederic Nicholls (Canadian General Electric) to W.B. Rankine, 17 December 1897

A letter from 2nd Vice President and General Manager of Canadian General Electric Company, Frederic Nicholls to W. B. Rankine regarding a bid for contract. The letter mentions that the bid for two alternating generators for the Canadian side of Niagara Falls was won by Westinghouse Eletric and Manufacturing Co. Nicholls also mentions that there will be other opportunites to win contracts as more machines are required. Nicholls also implies that Westinghouse may have bid under cost in an effort to secure the first of many contracts with the Canadian Niagara Power Company.

Letter - F. Nicholls to W.B. Rankine, 17 January 1902

A letter from Second V.P. Frederic Nicholls of Canadian General Electric Co. to W.B. Rankine in regards to transformers. The Canadian Niagara Power Co. has agreed to an order of nine transformers (1250 Killowatt) to be installed in the Power House at Niagara Falls. The transformers will cost the Canadian Niagara Power Company forty three thousand two hundred dollars.

Portsmouth Oracle, 15 January 1814 (vol. 25, no. 17) - Newspaper

Volumes of interest were published between 1812 and 1815 with articles about the War of 1812. Issue for July 16, 1814 includes a long report on the capture of Fort Erie on the Canadian-U.S. frontier, also a prominent front page headline and a very long and detailed report of the capture of the U.S. frigate USS Essex.

Portsmouth Oracle, 17 December 1814 (vol. 25, no. 65) - Newspaper

Volumes of interest were published between 1812 and 1815 with articles about the War of 1812.

The Washingtonian, 17 May 1813 (vol. 3, no. 148) - Newspaper

Volumes of interest were published between 1812 and 1815 with articles about the War of 1812. Issue for July 12, 1813 includes an account of the capture of the Chesapeake, report of explosion of the schooner Eagle off New London, report Com. Hardy had detained a smack, was determined to destroy all smacks and other small craft he found, reports of recent events at Malden, Fort George, head of the Lake, Sacketts Harbour, two reports of attack on Hampton, report of British attack near point of Nansemond River/Craney Island, second report of battle on/near Craney Island, additional report of attack at Hampton, marine news from Baltimore, report that sickness rampant throughout Army, many deaths reported, report that British were fortifying Brownstown, but deserters from British believe Michigan could be retaken by 3000 troops, report Gen. Boyd remained at Fort George to supervise repair of fortifications, report British reinforced from Kingston in Niagara and in Malden, report Gen. Hampton arrived at Albany on way to Burlington, report Gen. Parker left Albany, headed to Burlington, report of 400 men marching from Greenbush to the frontier, report of battles at Stoney Creek, 40 Mile Creek, report that Gen. Boyd lost an action with British in which 8 to 10 hundred men killed and taken from Americans, reports British had captured stores at Black Rock, Sodus, and Oswego, report of British victory in a battle 5 miles from Queenston, troop strength under Dearborn in Niagara reported between 2 and 3 thousand, additional reports of Battle of Beaverdams, reports Dearborn had resumed command, after lengthy illness, Gen. Boyd remained at Fort George, reports natives had been sieging Fort Wayne.