1. 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

2. 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

3. 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

4. “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

5. Benefit of being male – quantity of offspring
A. Sex Determination
Environmental Sex Determination
a. Temperature
b. Size/Nutrition
Benefit of being male – quantity of offspring
Benefit of being female – regulate quality of offspring
Cervus elaphus
Red deer
Starving pregnant females selectively abort male embryos. Small daughters may still mate; small sons will not acquire a harem and will not mate. Selection has favored females who save their energy, abort male embryos when starving, and maybe live to reproduce next year.

6. 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.

7. A. Sex Determination Midas cichlid Brood Becomes…
Environmental Sex Determination
a. Temperature
b. Size/Nutrition
c. Social Environment
Midas cichlid
Brood Becomes…
Add smaller juveniles
male
Add Larger juveniles
female

8. 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

9. 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”

10. 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

11. The ratio of X’s to autosomal sets determines sex
A. Sex Determination
Environmental Sex Determination
Chromosomal Sex Determination
a. Protenor sex determination
b. Lygaeus sex determination
c. Balanced sex determination
The ratio of X’s to autosomal sets determines sex
Human genotype and sex
2n: , XX = female
2n: , XY =male
2n+1: 47, XXY = male
2n-1: 45, X = female
Have a Y = male
No Y = female
Drosophila genotype and sex
2n: , XX =female
2n: , XY = male
2n+1: 9, XXY = female
2n-1: 7, X = male
Ratio of autosomal sets:X = 2:1 = male
Ratio of autosomal sets:X = 1:1 = female

12. Sex Determination
Gender
‘Gender’ is a role or behavior that a human society correlates with a sex
Behavior: wear make-up and a skirt
Modern USA Society:
Gender = woman
Medieval Scotland, modern Wodaabe: Gender = man

13. Sex Determination Gender
‘Gender’ is a role or behavior that a human society correlates with a sex
Sexual Behavior: like most behaviors, a given sexual behavior is not necessarily restricted to one sex or another.
And sex is used for more than procreation; it is used for communication, conflict resolution, deception, and establishing dominance within and between sexes.
Female Bonobo chimps (Pan paniscus)
‘sneaker’ male

14. A X A Y a X AaXX AaXY a X a Y A X Aa XX Aa XY Sex Determination Gender
Sex Linkage
1. For Comparison –heredity for sex (as a trait) and an autosomal dominant trait.
MALE: AAXY
FEMALE: aa XX
A X
A Y
a X
AaXX
AaXY
MALE: aa XY
FEMALE:
AA XX
a X
a Y
A X
Aa XX
Aa XY
All offspring, regardless of sex, express the A trait in both reciprocal crosses

15. Xg Y XG XGXg XGY XG Y Xg XGXg XgY Sex Determination Gender Sex Linkage
1. For Comparison –heredity for sex (as a trait) and an autosomal dominant trait.
2. 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.

16. 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.