Sexual selections in the northern fall field cricket, Gryllus pennsylvanicus: a manipulation of the adult sex ratio

The operational sex ratio has long been considered an important constraint on the structure of mating systems. The effects of an experimentally manipulated sex ratio on mating behavior and selection were investigated in a polygynous species, Gryllus pennsylvanicus, where the potential exists for spatial/temporal fluctuations in sex ratio of field populations. Four different sex ratios (males: females, 5:0, 5:2, 5:5, 5:10) were investigated. Observations were conducted in late summer over two field seasons, from 2400 h , to 1000 h EST. Several male characters thought to be associated with male reproduc.tive success were studied: calling duration, searching distance, weight, fighting behavior, courtship frequency, and mating success. Variance in male mating success was used as the indicator for the opportunity for sexual selection. Total selection was estimated as the univariate regression coefficient between relative fitness and the character of interest, while direct selection was estimated as standardized partial regression coefficients generated from a multiple regression of relative fitness on each character. The opportunity for sexual selection was highest at 5:2 and lowest at 5:10. The frequency of fighting behavior was highest at 5:2 and 5:5. Fighting ability (% wins) was determined to be an important correlate of male body weight. Direct selection for increased male body weight was detected at 5:2, while total selection for body weight was seen at 5:5. Selection on male body weight was not detected at 5: 10. Calling duration decreased as sex ratio became more female-biased. Total and direct selection were detected for increased calling at 5:2, only total selection for calling was seen at 5:5, whereas direct selection against calling was detected at 5: 10. Searching distance also decreased as sex ratio became more female-biased, however no form of selection was detected for searching at any of the sex ratios. Data are discussed in terms of sexual selection on male reproductive tactics, the mating system and maintenance of genetic variation in male reproductive behavior.

Tunis's topographical and pictorial guide to Niagara : containing, also, a description of the route through Canada, and the great northern route, from Niagara Falls to Montreal, Boston, and Saratoga Springs. Also, full and accurate tables of distances on all railroads running to and from Niagara Falls. --

Cover title: Tunis's guide to Niagara and traveller's companion, illustrated.

Appleton's northern and eastern Traveller's guide

Full Title: Appleton's northern and eastern Traveller's guide : with new and authentic maps, illustrating those divisions of the country; forming likewise a complete guide to the Middle States, Canada, New Brunswick, and Nova Scotia, the White Mountains, Catskill Mountains, Niagara and Trenton Falls, Saratoga and Virginia Springs andc.; with the fashionable and healthful resort, and full and accurate descriptions of the principal cities, towns, villages; with distances, fares, andc.; illustrated with numerous maps and plans of cities, engraved on steel, and several wood engravings

Message from the President of the United States, transmitting a letter from the Marshall of the Northern District of the State of New York, respecting disturbances on the Canadian frontier (1838)

Message from the President of the United States transmitting a letter from the Marshal of the Northern District of the State of New York, respecting Disturbances on the Canadian Frontier.

Certificate to Announce Thomas Henderson Captain of a Company of the Northern Regiment

Certificate (vellum) to announce that Thomas Henderson is to be Captain of a company of the Northern Regiment of Local Militia in the County of Northumberland, England. The document is stained, faded and contains holes. The text is slightly affected. The signature on this document has been cut away, Sept. 4, 1813.

Pay roll voucher #13 from the Engineer Department of Port Dalhousie and Thorold Railway Extension for the Northern Division for the month of April, 1857 approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, April 27, 1857

Pay roll voucher #13 from the Engineer Department of Port Dalhousie and Thorold Railway Extension for the Northern Division for the month of April, 1857 approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, April 27, 1857.

Pay roll voucher # 17 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division for the month of May, 1857, approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, May 27, 1857

Pay roll voucher # 17 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division for the month of May, 1857, approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, May 27, 1857.

Voucher from the Engineer Department of Port Dalhousie and Thorold Railway Extension for W.G. Thompson for the Northern Division. There are attached notes from the Welland Railway Company to John Mitchell for putting up shelves; to William Waud, staff; and to William Martin to repair the office (copy), June 10, 1857

Voucher from the Engineer Department of Port Dalhousie and Thorold Railway Extension for W.G. Thompson for the Northern Division. There are attached notes from the Welland Railway Company to John Mitchell for putting up shelves; to William Waud, staff; and to William Martin to repair the office (copy), June 10, 1857.

Pay roll voucher #20 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer (copy) June 1857

Pay roll voucher #20 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer (copy) June 1857.

Pay roll voucher #25 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division, for the month of July, 1857 approved by F. Shanly, chief engineer and W. G. Thompson (copy), July 30, 1857

Pay roll voucher #25 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division, for the month of July, 1857 approved by F. Shanly, chief engineer and W. G. Thompson (copy), July 30, 1857.

Pay roll voucher #32 from the Engineer Department of the Welland Railway for the Northern Division for the month of September

Pay roll voucher #32 from the Engineer Department of the Welland Railway for the Northern Division for the month of September, Oct. 2, 1857.

Pay roll voucher #36 from the Engineer Department of the Welland Railway for the Northern Division for the month of October

Pay roll voucher #36 from the Engineer Department of the Welland Railway for the Northern Division for the month of October, Nov. 3, 1857.

Pay roll voucher #43 from the Engineer Department of the Welland Railway for the Northern Division for the month of December

Pay roll voucher #43 from the Engineer Department of the Welland Railway for the Northern Division for the month of December, Dec. 30, 1857.