Effects of Incubation Temperature on Sex Ratios in Pine Snakes: Differential Vulnerability of Males and Females

1988 ◽  
Vol 132 (4) ◽  
pp. 492-505 ◽  
Author(s):  
Joanna Burger ◽  
R. T. Zappalorti
Keyword(s):  
Incubation Temperature ◽  
Sex Ratios ◽  
Differential Vulnerability ◽  
Pine Snakes ◽  
Males And Females

A new male-killing parasitism:Spiroplasmabacteria infect the ladybird beetleAnisosticta novemdecimpunctata(Coleoptera: Coccinellidae)

Parasitology ◽  
2006 ◽  
Vol 132 (6) ◽  
pp. 757-765 ◽  
Author(s):  
M. C. TINSLEY ◽  
M. E. N. MAJERUS
Keyword(s):  
Phylogenetic Analysis ◽  
Sex Ratio ◽  
High Efficiency ◽  
Sex Ratios ◽  
Egg Hatch ◽  
Hatch Rate ◽  
Male Killing ◽  
Offspring Sex ◽  
Novel Host ◽  
Males And Females

Whilst most animals invest equally in males and females when they reproduce, a variety of vertically transmitted parasites has evolved the ability to distort the offspring sex ratios of their hosts. One such group of parasites are male-killing bacteria. Here we report the discovery of females of the ladybirdAnisosticta novemdecimpunctatathat produced highly female-biased offspring sex ratios associated with a 50% reduction in egg hatch rate. This trait was maternally transmitted with high efficiency, was antibiotic sensitive and was infectious following experimental haemolymph injection. We identified the cause as a male-killingSpiroplasmabacterium and phylogenetic analysis of rDNA revealed that it belongs to theSpiroplasma ixodetisclade in which other sex ratio distorters lie. We tested the potential for interspecific horizontal transfer by injection from an infectedA. novemdecimpunctataline into uninfected individuals of the two-spot ladybirdAdalia bipunctata. In this novel host, the bacterium was able to establish infection, transmit vertically and kill male embryos.

scholarly journals Analysis of the sex ratio in Bradysia matogrossensis (Diptera, Sciaridae)

2000 ◽  
Vol 23 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Lincoln S. Rocha ◽  
André Luiz P. Perondini
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
X Chromosome ◽  
Control Mechanism ◽  
Sex Ratios ◽  
Laboratory Strain ◽  
Chromosome Elimination ◽  
Common Control ◽  
Males And Females ◽  
Successive Generations

In sciarid flies, the control of sex determination and of the progeny sex ratio is exercised by the parental females, and is based on differential X-chromosome elimination in the initial stages of embryogenesis. In some species, the females produce unisexual progenies (monogenic females) while in others, the progenies consist of males and females (digenic females). The sex ratio of bisexual progenies is variable, and departs considerably from 1:1. Bradysia matogrossensis shows both monogenic and digenic reproduction. In a recently established laboratory strain of this species, 15% of the females were digenic, 10% produced only females, 13% produced only males, and 62% produced progenies with one predominant sex (33% predominantly of female and 29% predominantly male progenies). These progeny sex ratios were maintained in successive generations. Females from female-skewed progenies yielded female- and male-producing daughters in a 1:1 ratio. In contrast, daughters of females from male-skewed progenies produce bisexual or male-skewed progenies. The X-chromosome of B. matogrossensis shows no inversion or other gross aberration. These results suggest that the control of the progeny sex ratio (or differential X-chromosome elimination) involves more than one locus or, at least, more than one pair of alleles. The data also suggest that, in sciarid flies, monogeny and digeny may share a common control mechanism.

scholarly journals Consistent sex ratio bias of individual female dragon lizards

2006 ◽  
Vol 2 (4) ◽  
pp. 569-572 ◽  
Author(s):  
Tobias Uller ◽  
Beth Mott ◽  
Gaetano Odierna ◽  
Mats Olsson
Keyword(s):  
Genetic Variation ◽  
Sex Ratio ◽  
Incubation Temperature ◽  
Sex Ratios ◽  
Phenotypic Traits ◽  
Female Size ◽  
Offspring Sex Ratio ◽  
Phenotypic Differences ◽  
Sex Ratio Bias ◽  
Offspring Sex

Sex ratio evolution relies on genetic variation in either the phenotypic traits that influence sex ratios or sex-determining mechanisms. However, consistent variation among females in offspring sex ratio is rarely investigated. Here, we show that female painted dragons ( Ctenophorus pictus ) have highly repeatable sex ratios among clutches within years. A consistent effect of female identity could represent stable phenotypic differences among females or genetic variation in sex-determining mechanisms. Sex ratios were not correlated with female size, body condition or coloration. Furthermore, sex ratios were not influenced by incubation temperature. However, the variation among females resulted in female-biased mean population sex ratios at hatching both within and among years.

scholarly journals Population viability at extreme sex-ratio skews produced by temperature-dependent sex determination

2017 ◽  
Vol 284 (1848) ◽  
pp. 20162576 ◽  
Author(s):  
Graeme C. Hays ◽  
Antonios D. Mazaris ◽  
Gail Schofield ◽  
Jacques-Olivier Laloë
Keyword(s):  
Sex Determination ◽  
High Mortality ◽  
Egg Production ◽  
Incubation Temperature ◽  
Sea Turtles ◽  
Sex Ratios ◽  
Population Viability ◽  
Temperature Dependent ◽  
Population Extinction ◽  
The World

For species with temperature-dependent sex determination (TSD) there is the fear that rising temperatures may lead to single-sex populations and population extinction. We show that for sea turtles, a major group exhibiting TSD, these concerns are currently unfounded but may become important under extreme climate warming scenarios. We show how highly female-biased sex ratios in developing eggs translate into much more balanced operational sex ratios so that adult male numbers in populations around the world are unlikely to be limiting. Rather than reducing population viability, female-biased offspring sex ratios may, to some extent, help population growth by increasing the number of breeding females and hence egg production. For rookeries across the world ( n = 75 sites for seven species), we show that extreme female-biased hatchling sex ratios do not compromise population size and are the norm, with a tendency for populations to maximize the number of female hatchlings. Only at extremely high incubation temperature does high mortality within developing clutches threaten sea turtles. Our work shows how TSD itself is a robust strategy up to a point, but eventually high mortality and female-only hatchling production will cause extinction if incubation conditions warm considerably in the future.

scholarly journals Incubation temperature causes skewed sex ratios in a precocial bird

2016 ◽  
Vol 219 (13) ◽  
pp. 1961-1964 ◽  
Author(s):  
Sarah E. DuRant ◽  
William A. Hopkins ◽  
Amanda W. Carter ◽  
Laila T. Kirkpatrick ◽  
Kristin J. Navara ◽  
...  
Keyword(s):  
Incubation Temperature ◽  
Sex Ratios ◽  
Precocial Bird

Sex Ratios and Lengths of Adult Sea Lampreys (Petromyzon marinus) from a Lake Ontario Tributary

1974 ◽  
Vol 31 (1) ◽  
pp. 122-124 ◽  
Author(s):  
I. C. Potter ◽  
F. W. H. Beamish ◽  
B. G. H. Johnson
Keyword(s):  
Narrow Range ◽  
Sex Ratios ◽  
Petromyzon Marinus ◽  
Lake Ontario ◽  
Sea Lamprey ◽  
Adult Males ◽  
Sea Lampreys ◽  
Males And Females ◽  
The Mean ◽  
Humber River

The mean lengths of adult males and females of the sea lamprey (Petromyzon marinus) migrating into the Humber River from Lake Ontario in each of the years 1968–1972 varied little, and were similar to those found by other workers in recently established populations in the upper lakes. In contrast, the ratio of males to females, which lay within the narrow range of 1:1 to 1.26:1, was similar to those reported for long-established populations.

scholarly journals Temperature-dependent sex-biased embryo mortality in a bird

2008 ◽  
Vol 275 (1652) ◽  
pp. 2703-2706 ◽  
Author(s):  
Yvonne A Eiby ◽  
Jessica Worthington Wilmer ◽  
David T Booth
Keyword(s):  
Low Temperatures ◽  
Incubation Temperature ◽  
Sex Ratios ◽  
Molecular Sexing ◽  
Temperature Dependent ◽  
Female Embryo ◽  
Male Embryo ◽  
Diverse Range ◽  
Embryo Mortality ◽  
Incubation Temperatures

Sex ratios have important evolutionary consequences and are often biased by environmental factors. The effect of developmental temperature on offspring sex ratios has been widely documented across a diverse range of taxa but has rarely been investigated in birds and mammals. However, recent field observations and artificial incubation experiments have demonstrated that the hatching sex ratio of a megapode, the Australian brush-turkey ( Alectura lathami ), varied with incubation temperature; more females hatched at high incubation temperatures and more males hatched at low temperatures. Here, we investigated the causes of this temperature-dependent sex-biasing system. Molecular sexing of chicks and embryos confirmed that male embryo mortality was greater at high temperatures while female embryo mortality is greater at low temperatures, with mortality in both sexes similar at intermediate incubation temperatures. Temperature-dependent sex-biased embryo mortality represents a novel mechanism of altering sex ratios in birds. This novel mechanism, coupled with the unique breeding biology of the brush-turkey, offers a potentially unparalleled opportunity in which to investigate sex allocation theory in birds.

Are brightly coloured male ducks selectively shot by duck hunters?

1991 ◽  
Vol 69 (2) ◽  
pp. 279-282 ◽  
Author(s):  
Karen J. Metz ◽  
C. Davison Ankney
Keyword(s):  
Significant Interaction ◽  
Management Unit ◽  
Differential Vulnerability ◽  
Males And Females ◽  
Hunting Mortality

In many species of ducks, males are harvested at higher rates than females. Several studies have suggested that particular aspects of the birds' biology may account for this difference, but few studies have attempted to determine the effect of hunter behaviour on the differential vulnerability. The objective of this study was to determine if the bright plumage of male ducks was related to greater hunting mortality. Ducks shot from pairs at Long Point Waterfowl Management Unit, Ontario, from September 25 to November 26, 1987, were examined, and questions were asked of hunters who brought the ducks into the Waterfowl Management Unit's check station. Sixty-one percent of ducks shot from pairs were mallards, green-winged teal, or ring-necked ducks. A significant interaction occurred between the degree of dichromatism of plumage and which sex of duck was shot. Approximately equal numbers of males and females were shot when males resembled females. However, when males obtained their full, bright, alternate plumage, a significantly greater proportion of males were shot regardless of which sex was leading. These data suggest that hunters select, consciously or unconsciously, the more distinctive male when he is accompanied by a female. Characteristics of hunters' behaviour while hunting are pertinent to assessing current waterfowl management programs.

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