Heredity, Gene Regulation, and Development I. Mendel's Contributions II. Meiosis and the Chromosomal Theory III. Allelic, Genic, and Environmental Interactions IV. Sex Determination and Sex Linkage
Heredity, Gene Regulation, and Development I. Mendel's Contributions II. Meiosis and the Chromosomal Theory III. Allelic, Genic, and Environmental Interactions IV. Sex Determination and Sex Linkage A. Sex Determination Environmental Sex Determination a. Temperature MT FT
Heredity, Gene Regulation, and Development I. Mendel's Contributions II. Meiosis and the Chromosomal Theory III. Allelic, Genic, and Environmental Interactions IV. Sex Determination and Sex Linkage A. Sex Determination Environmental Sex Determination a. Temperature MT FT
“Jack-in-the-Pulpit” A. Sex Determination Environmental Sex Determination a. Temperature b. Size/Nutrition Arisaema triphyllum “Jack-in-the-Pulpit” Small plants - male Large plants - female
Sexually mature female A. Sex Determination Environmental Sex Determination a. Temperature b. Size/Nutrition c. Social Environment Sexually mature female (Inhibits development of males) Sexually mature male Immature males Wouldn’t the species do better if there were more females/group? Yes, but selection favors individual reproductive success.
The presence of 1 or 2 sex chromosomes determines sex A. Sex Determination Environmental Sex Determination Chromosomal Sex Determination a. Protenor sex determination The presence of 1 or 2 sex chromosomes determines sex Order: Hemiptera “True Bugs” Family Alydidae – Broad-headed bugs
The type of sex chromosomes determines sex A. Sex Determination Environmental Sex Determination Chromosomal Sex Determination a. Protenor sex determination b. Lygaeus sex determination The type of sex chromosomes determines sex Order: Hemiptera Family: Lygaeidae “Chinch/Seed Bugs”
Which sex is the ‘heterogametic’ sex varies A. Sex Determination Environmental Sex Determination Chromosomal Sex Determination a. Protenor sex determination b. Lygaeus sex determination Which sex is the ‘heterogametic’ sex varies XX female, XY – male Most mammals, including humans Some insects Some plants ZZ male, ZW female Birds Some fish Some reptiles Some insects (Butterflies/Moths) Some plants
Xg Y XG XGXg XGY XG Y Xg XGXg XgY Sex Determination Gender Sex Linkage example: red-green coloblindness in humans MALE FEMALE Xg Y XG XGXg XGY MALE FEMALE XG Y Xg XGXg XgY 100% G, for all offspring 50% G daughters, 50% g sons Now, the sex of the parent that expresses the G trait matters; the transmission of this gene correlates with the sex of the offspring, because this trait and ‘sex’ are influenced by the same chromosome.
Queen Victoria of England Her daughter Alice X-linked recessive traits are expressed in males more than females, because females get a second X that may carry the dominant allele.