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
1. 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
1. 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
1. Environmental Sex Determination
a. Temperature
MT
FT
A. Sex Determination
1. Environmental Sex Determination
a. Temperature
b. Size/Nutrition
Arisaema triphyllum
“Jack-in-the-Pulpit”
Small plants - male
Large plants - female
A. Sex Determination
1. 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.
A. Sex Determination
1. 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.
A. Sex Determination
1. Environmental Sex Determination
a. Temperature
b. Size/Nutrition
c. Social Environment
Midas cichlid
Brood
A. Sex Determination
1. Environmental Sex Determination
a. Temperature
b. Size/Nutrition
c. Social Environment
Midas cichlid
Add Larger juveniles
Brood
female
A. Sex Determination
1. Environmental Sex Determination
a. Temperature
b. Size/Nutrition
c. Social Environment
Midas cichlid
Add smaller juveniles
Brood
male
A. Sex Determination
1. Environmental Sex Determination
2. 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
A. Sex Determination
1. Environmental Sex Determination
2. 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”
A. Sex Determination
1. Environmental Sex Determination
2. Chromosomal Sex Determination
a. Protenor sex determination
b. Lygaeus sex determination
Which sex is the ‘heterogametic’ sex varies
XX female, XY – male
ZZ male, ZW female
Most mammals, including
humans
Some insects
Some plants
Birds
Some fish
Some reptiles
Some insects (Butterflies/Moths)
Some plants
A. Sex Determination
1. Environmental Sex Determination
2. 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
Drosophila genotype and sex
2n: 46, XX = female
2n: 46, XY =male
2n+1: 47, XXY = male
2n-1: 45, X
= female
2n:
2n:
2n+1:
2n-1:
Have a Y = male
No Y = female
Ratio of autosomal sets:X = 2:1 = male
Ratio of autosomal sets:X = 1:1 = female
8, XX =female
8, XY = male
9, XXY = female
7, X = male
A. Sex Determination
B. 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
A. Sex Determination
B. 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
A. Sex Determination
B. Gender
C. Sex Linkage
A. Sex Determination
B. Gender
C. Sex Linkage
1. For Comparison –heredity for sex (as a trait) and an autosomal dominant trait.
MALE: AAXY
AX
FEMALE:
aa XX
MALE: aa XY
AY
aX
AaXX AaXY
aX
AaXX AaXY
aX
FEMALE:
AA XX
aY
AX
Aa XX Aa XY
AX
Aa XX Aa XY
All offspring, regardless of sex, express the A trait in both reciprocal crosses
A. Sex Determination
B. Gender
C. 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
XG
XGXg
XGY
100% G, for all offspring
MALE
FEMALE
XG
Y
Xg
XGXg
XgY
Xg
XGXg
XgY
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.