Temperature is considered as a consumer- and environment-friendly instrument with applications in selective fish breeding. Environmental masculinization figure 1 a reduces the proportion of genetic males and can eventually lead to the extinction of Y-chromosomes, while environmental feminization figure 1 b can elevate the proportion of genetic males and can theoretically drive X-chromosomes to extinction [ 414253 ] but extinction of X-chromosomes requires far stronger rates of ESR than extinction of Y-chromosomes [ 42 ].
Two distinct natural mutations in the dmy gene present in wild medaka populations have been shown to induce XY genotypes to become fertile females [ 31 ]. The diversity of sex determination systems within fish, for example, extends deep into families [ 13 ], and there are several cases of within-species population differences in fish and other taxa [ 70 ].
See text for a discussion of the mating scenarios.
Moreover, N e is negatively affected if masculinization increases the variance in reproductive success among phenotypic males, for example, because sexual selection may act differently on XX- and XY-males or because of possible effects of distorted sex ratios on male and female life history [ 6061 ].
Results Our results show that of the 53—55 species depending on the authors previously assigned to pattern 1, the 33 cichlid species of the genus Apistogramma indeed exhibit pattern 1 Fig. Climate change effects on the sex ratio have already been inferred for some sea turtles with TSD but are lacking for fish.
However, only seven other species of the remaining 20—22 adhere to pattern 1 and have TSD Fig. They still agree with the view that TSD has evolved independently many times but we find TSD to be present in only four orders, which include only three of the seven used by Mank et al.
Experimental mostly laboratory data were also compiled from the primary literature, as indicated in Table S1. Mrosovsky, S. Close banner Close.
Specifically, that facultative sex ratio variation will only be favoured when the fitness benefits of this behaviour are greater than its costs. Download citation. Population genetics of a parasitic chromosome: experimental analysis of PSR in subdivided populations.
The demographic and genetic consequences then need to be modelled. The sdY sequence is highly conserved in all salmonids and is a male specific Y-chromosome gene in the majority of these species except in two whitefish species subfamily Coregoninae [ 60 ].