The Effect of Three Distinct Sex Ratios at Two Oesophagostomum dentatum Worm Population Densities

1997 ◽  
Vol 83 (4) ◽  
pp. 636 ◽  
Author(s):  
Charlotte M. Christensen
Keyword(s):  
Sex Ratios ◽  
Population Densities ◽  
Oesophagostomum Dentatum

Survival and Reproduction of Nasonia vitripennis (Walk.) at Different Host Population Densities

1966 ◽  
Vol 98 (3) ◽  
pp. 275-281 ◽  
Author(s):  
H. G. Wylie
Keyword(s):  
Musca Domestica ◽  
Sex Ratios ◽  
Host Population ◽  
Population Densities ◽  
Nasonia Vitripennis ◽  
Survival And Reproduction

AbstractFemales of Nasonia vitripennis (Walk.) lived longer, found more hosts, and produced more progeny at high host (housefly, Musca domestica L.) population densities than at lower ones. Because they feed on the fly pupae that they parasitize, the female parasites were able to obtain more food at high host population densities. Starved and unstarved females produced progeny with similar sex ratios. By feeding on parasitized fly pupae when unparasitized ones are scarce, females of N. vitripennis increase their longevity and their ability to oviposit if they subsequently find unparasitized hosts. Females that have fed partly or entirely on parasitized pupae subsequently produce relatively more diapause progeny.

Demographic differences among populations of Northern Map Turtles (Graptemys geographica) in intact and fragmented sites

2009 ◽  
Vol 87 (12) ◽  
pp. 1147-1157 ◽  
Author(s):  
A. M. Bennett ◽  
M. Keevil ◽  
J. D. Litzgus
Keyword(s):  
Growth Rates ◽  
Sex Ratios ◽  
Habitat Alteration ◽  
Population Densities ◽  
Demographic Differences ◽  
Fragmented Habitats ◽  
Habitat Alterations ◽  
Map Turtles ◽  
Graptemys Geographica ◽  
Northern Map Turtle

Habitat fragmentation is a leading cause of reptile declines worldwide. We examined demographic differences between populations of Northern Map Turtles, Graptemys geographica (Le Sueur, 1817), inhabiting intact and fragmented sites along the Trent–Severn Waterway (TSW) in Ontario over two field seasons. We examined population densities, sex ratios, body size, and growth rates in two control sites and two fragmented sites (where the waterway is disrupted by dams). We predicted that population density would be higher in control sites, and that sex ratios would differ among sites. Abundance was greater than expected, but densities could not be compared owing to a lack of recaptures. Sex ratios in control sites were slightly male-biased and were significantly female-biased in fragmented sites. Turtles in fragmented habitats were significantly smaller than those in control habitats. Estimated growth rates of juveniles and males were significantly reduced in fragmented populations compared with controls. We hypothesize that habitat alterations in fragmented sites are differentially affecting demographic classes because of the intersexual niche divergence observed in Map Turtles. We emphasize the need for further research to examine the interactions between habitat alteration and invasive species and the effects they are having on Northern Map Turtle populations.

Use of Bag Records of Big Game to Determine Sex Ratios and Population Densities

1943 ◽  
Vol 7 (1) ◽  
pp. 11 ◽  
Author(s):  
Rollin H. Baker ◽  
Hilbert R. Siegler
Keyword(s):  
Sex Ratios ◽  
Population Densities

Conservation Status and Sex Ratios of the Coahuila Box Turtle (Terrapene coahuila) in the Cuatro Ciénegas Valley of Coahuila, Mexico, 2011–2018

2020 ◽  
Vol 19 (1) ◽  
pp. 14
Author(s):  
Gamaliel Castañeda Gaytan ◽  
Ernesto Becerra-López ◽  
Sara Valenzuela-Ceballos ◽  
Miguel Borja-Jiménez ◽  
Bruno Rodríguez-López ◽  
...  
Keyword(s):  
Conservation Status ◽  
Sex Ratios ◽  
Box Turtle ◽  
Cuatro Ciénegas

Effects of Seed Treatments and a Soil-applied Nematicide on Corn Yields and Nematode Population Densities

2013 ◽  
Author(s):  
Gregory L. Tylka ◽  
Mychele Batista da Silva ◽  
Joel L. DeJong ◽  
Joshua L. Sievers ◽  
Ryan Rusk
Keyword(s):  
Nematode Population ◽  
Seed Treatments ◽  
Population Densities
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