Sex ratio under the haystack model.
D000818:Animals; D005075:Biological Evolution; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D008297:Male; D008954:Models, Biological; D011157:Population Dynamics; D011158:Population Growth; D012377:Rodentia; D012732:Sex Determination Analysis; D012744:Sex Ratio