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.

Mr. Hillhouses' speech, on the resolution to repeal the embargo, November 29, 1808. --

Caption title.

Letter From Sir Isaac Brock to James FitzGibbon - July 29, 1812

A two page letter written by Sir Isaac Brock in York, Upper Canada to James FitzGibbon on July 29, 1812. The name of the recipient is not included but according to Mary Agnes FitzGibbon, one can find a transcript of the letter in her "A Veteran of 1812", page 60.[1812], 29 July: Major-General Isaac Brock, York, to James FitzGibbon. I lament that you should have been so long impressed with the idea that I possessed the means of being serviceable to you. I had scarcely heard of Mr. Johnson having declined a Company in the Glengarry (which would have given me the nomination) but I received account of his being reinstated. I consequently thought no more of the business thinking that officer was enjoying the fruits of his good fortune. I know not positively whether Mr. Johnson is reinstated, but being under obligations to promote his views, I cannot possibly interfere to his prejudice. I rather wonder you did not hear that Lieut Lamont had long ago my promise of nominating him to the Company provided it became vacant, which of course would have precluded my application in your behalf. Altho you must be sensible of the impossibility of my taking any step to forward your views in the present case, yet be assured I shall always feel happy in any opportunity that may offer to do your service. To a person unaccustomed to my writing I scarcely would hazard sending this scrawl. I am, Dear Sir, Yours faithfully, Isaac Brock I should like to be among the 49th at this moment. I am satisfied they will support and even add to their former fame. They have my very best wishes. The 41st are behaving nobly at Amherstburg.

The Military Monitor and American Register- 29 March 1813

The Military Monitor was a weekly periodical that was published every Monday. The first issue was printed for August 17, 1812 and is believed to have ceased in 1814, as the last issue located was April 2, 1814. The periodical was suspended with the November 23, 1812 issue and resumed with the December 14, 1812 issue. The quote at the top of the first page is "The public good our end". The periodical's various authors included: Desnoues, Joseph, 1794?-1837. O'Connor, Thomas, 1770-1855. Hardcastle, John, 1778?-1835. Van Pelt, Peter, 1779?-1843. Wall, Stephen. Van Riper, Nicholas. Other authors are believed to be the American Antiquarian Society. Proprietors: T. O'Connor and S. Wall, 1812; T. O'Connor, 1812- . Printers: Hardcastle and Van Pelt, for T. O'Connor and S. Wall, Sept. 14-Oct. 5, 1812; J. Desnoues, Oct. 12, 1812- ; N. Van Riper, Nov. 6, 1813- . This issue was included in a bound volume of the Military Monitor and American Register. Other Dates included are: 1812 August 31 1812 October 12 1812 October 19 1812 November 23 1812 December 14 1812 December 21 1813 January 11 1813 February 1 1813 April 5 1813 April 12 1813 April 26 1813 May 31

National Intelligencer Vol. XIII, No. 1993- June 29, 1813

The Intelligencer was an American newspaper that was established, in 1800, in Washington by Samuel Harrison Smith, a young Jeffersonian- Republican from Philadelphia. The paper was a supporter of the Jefferson and Madison administrations until 1810 when it was sold to Joseph Gales Jr. from North Carolina. In 1812 William Seaton joined Gales as a publishing partner. This paper made significant contributions to the nation and wielded considerable influence in political circles during its publication. It has been praised for its "high standard of journalistic excellence and high intellectual level of its contents". (William E. Ames , National Intelligencer: Washington's Leading Political Newspaper) The Intelligencer was, until 1810, named the National Intelligencer, and Washington Advertiser. It was a tri-weekly paper and had a peak circulation of 6, 000. Publication was suspended in 1869.

H.A.S. Dearborn letter, May 29, 1812

H.A.S. (Henry Alexander Scammell) Dearborn (1783-1851) was the son of Henry Dearborn, the American politician and veteran of the Revolutionary War and War of 1812. In the War of 1812, H.A.S Dearborn served as Brigadier General of the volunteer forces, responsible for the defence of Boston Harbour. From 1812-1829 he was collector of customs in Boston, from 1831-1833 he served as a representative from Massachusetts in the United States Congress, was adjutant general of Massachusetts from 1834-1843 and mayor of Roxbury from 1847-1851. Letter transcription: Dear Sir, My success in the line of recruiting has exceeded my most sanguine expectations. I have enlisted 24 1st Lt. 30—my 2nd Lt. 13, and my Ensign 9—Total 76. All very [ablebodied] men. In all probability my company will be full before the last day of June. I shall be in Boston on the 10th of June. I have not yet had the pleasure to hear of the arrival of your father at Boston. Please to offer my respects to your family, and to all my friends in the [office]. In haste, Yours, A.M. Clary.

Letter - James Wilson to Colonel Albert D. Shaw, 29 February 1892

A letter from James Wilson, Park Superintendent to Albert D. Shaw in the year 1892. Wilson describes plans to produce hydroelectric power using Niagara Falls. He details advantages to the plan in this five page correspondence with Shaw.

Portsmouth Oracle, 29 January 1814 (vol. 25, no. 19) - Newspaper

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

The War, 29 August 1812 (vol. 1, no. 10) - Newspaper

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

The War, 29 March 1814 (vol. 2, no. 41, whole no. 93) - Newspaper

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

H.A.S. Dearborn letter - May 29, 1812

Letter transcription: Dear Sir, My success in the line of recruiting has exceeded my most sanguine expectations. I have enlisted 24 1st Lt. 30—my 2nd Lt. 13, and my Ensign 9— Total 76. All very [ablebodied] men. In all probability my company will be full before the last day of June. I shall be in Boston on the 10th of June. I have not yet had the pleasure to hear of the arrival of your father at Boston. Please to offer my respects to your family, and to all my friends in the [office]. In haste, Yours, A.M. Clary.