Age, growth, and sex ratio among populations of least brook lamprey,Lampetra aepyptera, larvae: an argument for environmental sex determination

1994 ◽  
Vol 41 (1-4) ◽  
pp. 191-205 ◽  
Author(s):  
Margaret F. Docker ◽  
F. William ◽  
H. Beamish
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Environmental Sex Determination ◽  
Brook Lamprey ◽  
Lampetra Aepyptera

Heritability of Sex Ratio in Turtles with Environmental Sex Determination

Evolution ◽  
1982 ◽  
Vol 36 (2) ◽  
pp. 333 ◽  
Author(s):  
J. J. Bull ◽  
R. C. Vogt ◽  
M. G. Bulmer
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Environmental Sex Determination

scholarly journals Environmental Influences on Crustacean Sex Determination and Reproduction: Environmental Sex Determination, Parasitism, and Pollution

2020 ◽  
pp. 394-428
Author(s):  
Alison M. Dunn ◽  
Thierry Rigaud ◽  
Alex T. Ford
Keyword(s):  
Environmental Factors ◽  
Sex Ratio ◽  
Sex Determination ◽  
Environmental Influences ◽  
Host Population ◽  
Adaptive Mechanism ◽  
Environmental Sex Determination ◽  
Individual Fitness ◽  
Ratio Distortion ◽  
Sex Ratio Distortion

This chapter reviews the influences of environmental factors on sex determination, sex ratios, and reproductive behavior in the Crustacea, focusing in particular on amphipod and isopod examples. A range of abiotic and biotic environmental factors influence reproduction in Crustacea, including temperature, day length, pollutants, and parasites. Individual crustaceans may benefit from these environmental influences, but in other cases, reproductive biology responses to biotic and abiotic environments may be detrimental to individual fitness. Environmental Sex Determination (ESD) falls into the former category. ESD is an adaptive mechanism of sex determination that is rare, but has evolved in diverse taxa. Evidence from gammarid amphipods is used to explore the evolution of ESD in response to a patchy environment. While ESD is an adaptive mechanism of sex determination, the impact of other environmental factors can be very costly. Parasitic castrators can lead to a reduction or total cessation of reproduction in crustacean hosts, driving population declines. In contrast, parasitic feminizers convert male hosts into females, enhancing maternal parasite transmission but also leading to sex ratio distortion in the host population. The chapter discusses parasite-host coevolutionary conflict and reviews evidence that selection on the host in response to parasitic sex ratio distortion has led to altered mate choice in amphipods, and to the evolution of a novel system of sex determination in isopods. Human-induced environmental influences can also be seen in Crustacea, and the chapter discusses how parasites, ESD, and endocrine-disrupting chemicals can each affect sex determination and lead to abnormal intersex phenotypes. It ends by highlighting areas for future research on the diverse world of crustacean reproduction.

scholarly journals Do Covariances Between Maternal Behavior and Embryonic Physiology Drive Sex-Ratio Evolution Under Environmental Sex Determination?

2019 ◽  
Vol 110 (4) ◽  
pp. 411-421 ◽  
Author(s):  
Fredric J Janzen ◽  
David M Delaney ◽  
Timothy S Mitchell ◽  
Daniel A Warner
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Environmental Conditions ◽  
Oviposition Behavior ◽  
Thermal Sensitivity ◽  
Sex Ratios ◽  
Theoretical Work ◽  
Environmental Sex Determination ◽  
Turtle Species ◽  
Primary Sex Ratio

Abstract Fisherian sex-ratio theory predicts sexual species should have a balanced primary sex ratio. However, organisms with environmental sex determination (ESD) are particularly vulnerable to experiencing skewed sex ratios when environmental conditions vary. Theoretical work has modeled sex-ratio dynamics for animals with ESD with regard to 2 traits predicted to be responsive to sex-ratio selection: 1) maternal oviposition behavior and 2) sensitivity of embryonic sex determination to environmental conditions, and much research has since focused on how these traits influence offspring sex ratios. However, relatively few studies have provided estimates of univariate quantitative genetic parameters for these 2 traits, and the existence of phenotypic or genetic covariances among these traits has not been assessed. Here, we leverage studies on 3 species of reptiles (2 turtle species and a lizard) with temperature-dependent sex determination (TSD) to assess phenotypic covariances between measures of maternal oviposition behavior and thermal sensitivity of the sex-determining pathway. These studies quantified maternal behaviors that relate to nest temperature and sex ratio of offspring incubated under controlled conditions. A positive covariance between these traits would enhance the efficiency of sex-ratio selection when primary sex ratio is unbalanced. However, we detected no such covariance between measures of these categories of traits in the 3 study species. These results suggest that maternal oviposition behavior and thermal sensitivity of sex determination in embryos might evolve independently. Such information is critical to understand how animals with TSD will respond to rapidly changing environments that induce sex-ratio selection.

Environmental Sex Determination in Southern Brook Lamprey, Ichthyomyzon gagei

1993 ◽  
Vol 50 (6) ◽  
pp. 1299-1307 ◽  
Author(s):  
F. William H. Beamish
Keyword(s):  
United States ◽  
Sex Determination ◽  
Sex Ratios ◽  
Southeastern United States ◽  
Larval Density ◽  
Larval Growth ◽  
Age Groups ◽  
Differential Mortality ◽  
Environmental Sex Determination ◽  
Brook Lamprey

Sex ratios were determined for 20 populations of southern brook lamprey larvae, Ichthyomyzon gagei, collected from throughout much of their range in the southeastern United States. Ratios varied between 9 and 49% males. Differential mortality was an unlikely factor, as sex ratios were similar among age groups within each population. Environmental sex determination is suggested. Sex ratio varied with growth (expressed as length of larvae at specific ages), larval density, pH, and annual mean temperature of the natal stream. Generally, under conditions promoting rapid growth, the percentage of males varied directly with density and inversely with temperature. Where growth was slow, the percentage of males declined as larval density increased, the response being less at low than at high pH. Temperature had little effect when larval growth was slow. The percentage of males declined when growth was rapid under otherwise similar environmental conditions.

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