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 Immature males Sexually mature male Sexually mature female Wouldn’t the species do better if there were more females/group? Yes, but selection favors individual reproductive success. (Inhibits development of males)

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 BroodAdd Larger juveniles female

A. Sex Determination 1.Environmental Sex Determination a. Temperature b. Size/Nutrition c. Social Environment Midas cichlid BroodAdd smaller juveniles 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 Most mammals, including humans Some insects Some plants ZZ male, ZW female Birds Some fish Some reptiles Some insects (Butterflies/Moths) Some plants

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

MALE: AAXY FEMALE: aa XX A XA Y a XAaXXAaXY a XAaXXAaXY MALE: aa XY FEMALE: AA XX a Xa Y A XAa XXAa XY A XAa XXAa XY A.Sex Determination B.Gender C.Sex Linkage 1. For Comparison –heredity for sex (as a trait) and an autosomal dominant trait. All offspring, regardless of sex, express the A trait in both reciprocal crosses

MALE FEMALE XgXg Y XGXG XGXgXGXg XGYXGY XGXG XGXgXGXg XGYXGY MALE FEMALE XGXG Y XgXg XGXgXGXg XgYXgY XgXg XGXgXGXg XgYXgY 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 100% G, for all offspring50% 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.

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 V. Linkage A. Overview Aa Aa bBBb ABabAbaB Independent Assortment

V. Linkage A. Overview Aa Aa bBBb ABabAbaB Independent Assortment Aa Bb Linkage ABab

V. Linkage A. Overview Linkage Aa Bb ABab Aa Bb ABab In Prophase I of Meiosis – Crossing-over A a b B AbaB

X AABBaabb AB ab V. Linkage A.Overview B.Complete Linkage Test Cross

- if genes are immediate neighbors, they are almost never separated by crossing over and are ‘always’ inherited together. The pattern mimics that of a single gene. X AABBaabb AB ab ABab Gametes AB ab F1 V. Linkage A.Overview B.Complete Linkage

- if genes are immediate neighbors, they are almost never separated by crossing over and are ‘always’ inherited together. The pattern mimics that of a single gene. X ABab Gametes AB ab F1 x F1 ab V. Linkage A.Overview B.Complete Linkage

- if genes are immediate neighbors, they are almost never separated by crossing over and are ‘always’ inherited together. The pattern mimics that of a single gene. F1 x F1 X AB ab Gametes AB ab AaBb aabb 1:1 ratio A:a 1:1 ratio B:b 1:1 ratio AB:ab NOT 1:1:1:1 V. Linkage A.Overview B.Complete Linkage Phenotypes AB ab aB ? Ab ?

C. Incomplete Linkage B ab A b ab a

- So, since crossing-over is rare (in a particular region), most of the time it WON’T occur and the homologous chromosomes will be passed to gametes with these genes in their original combination…these gametes are the ‘parental types’ and they should be the most common types of gametes produced. B ab b ab a AB ab A

C. Incomplete Linkage - But during Prophase I, homologous chromosomes can exchange pieces of DNA. - This “Crossing over” creates new combinations of genes… These are the ‘recombinant types’ B ab b ab a AB ab A aB Ab

C. Incomplete Linkage As the other parent only contributed recessive alleles, the phenotype of the offspring is determined by the gamete received from the heterozygote… B ab b ab a AB ab A aB Ab gamete genotype phenotype abaabbab AaBbAB abaaBbaB abAabbAb LOTS of these FEW of these

V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently:

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb The frequency of ‘AB’ should = f(A) x f(B) x N = 55/100 x 51/100 x 100 = 28 The frequency of ‘Ab’ should = f(A) x f(B) x N = 55/100 x 49/100 x 100 = 27 The frequency of ‘aB’ should = f(a) x f(B) x N = 45/100 x 51/100 x 100 = 23 The frequency of ‘ab’ should = f(a) x f(b) x N = 45/100 x 49/100 x 100 = 22 V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross - determine expectations under the hypothesis of independent assortment

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb BbRow Total A4312 a837 Col. Total V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross - determine expectations under the hypothesis of independent assortment Easy with a 2 x 2 contingency table

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb BbRow Total A a83745 Col. Total V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross - determine expectations under the hypothesis of independent assortment Easy with a 2 x 2 contingency table Compute Row, Columns, and Grand Totals

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb BExp.bRow Total A a83745 Col. Total V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross - determine expectations under the hypothesis of independent assortment Easy with a 2 x 2 contingency table Compute Row, Column, and Grand Totals E = (RT x CT)/GT

BExp.b Row Total A a Col. Total Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - test cross - determine expectations under the hypothesis of independent assortment Easy with a 2 x 2 contingency table Compute Row, Column, and Grand Totals E = (RT x CT)/GT

Phenotype ObsExp(o-e)(o-e) 2 /e AB Ab aB ab X 2 =36.38 BExp.b Row Total A a Col. Total V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: - Chi-Square Test of Independence

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: 2. Detemining the arrangement of alleles in the F1 individual; which alleles are paired on each homolog?

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb AB ab V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: 2. Detemining the arrangement of alleles in the F1 individual; which alleles are paired on each homolog? - most abundant types are ‘parental types’

AB ab aB Ab V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: 2. Detemining the arrangement of alleles in the F1 individual; which alleles are paired on each homolog? - most abundant types are ‘parental types’ - least abundant are products of crossing-over: ‘recombinant types’

Offspring Number AB43 Ab12 aB 8 ab37 AaBb x aabb AB ab 20 map units V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage 1. Determining if the genes are linked, or are assorting independently: 2. Detemining the arrangement of alleles in the F1 individual; which alleles are paired on each homolog? 3. Determining the distance between loci: Add the recombinant types and divide by total offspring; this is the percentage of recombinant types. Multiply by 100 (to clear the decimal) and this is the index of distance, in ‘map units’ or centiMorgans. 20/100 = 0.20 x100 = 20.0 centiMorgans

V. Linkage A.Overview B.Complete Linkage C.Incomplete Linkage D.Summary - by studying the combined patterns of heredity among linked genes, linkage maps can be created that show the relative positions of genes on chromosomes.

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 V. Linkage VI. Mutation A. Overview DON’T WORRY!! Just a photoshop award winner…

VI. Mutation A.Overview A change in the genome Occurs at four scales of genetic organization: 1: Change in the number of sets of chromosomes ( change in ‘ploidy’) 2: Change in the number of chromosomes in a set (‘aneuploidy’) 3: Change in the number and arrangement of genes on a chromosome 4: Change in the nitrogenous base sequence within a gene

VI. Mutation A.Overview B.Changes in Ploidy - These are the most dramatic changes, adding a whole SET of chromosomes Triploidy occurs in 2-3% of all human pregnancies, but almost always results in spontaneous abortion of the embryo. Some triploid babies are born alive, but die shortly after. Syndactyly (fused fingers), cardiac, digestive tract, and genital abnormalities occur.

VI. Mutation A.Overview B.Changes in Ploidy - These are the most dramatic changes, adding a whole SET of chromosomes 1.Mechanism #1: Complete failure of Meiosis - if meiosis fails, reduction does not occur and a diploid gamete is produced. This can occur because of failure of homologs OR sister chromatids to separate in Meiosis I or II, respectively. Failure of Meiosis I 2n = 4 Gametes: 2n = 4

VI. Mutation A.Overview B.Changes in Ploidy - These are the most dramatic changes, adding a whole SET of chromosomes 1.Mechanism #1: Complete failure of Meiosis - if meiosis fails, reduction does not occur and a diploid gamete is produced. This can occur because of failure of homologs OR sister chromatids to separate in Meiosis I or II, respectively. Failure of Meiosis II 2n = 4 Normal gamete formation is on the bottom, with 1n=2 gametes. The error occurred up top, with both sister chromatids of both chromosomes going to one pole, creating a gametes that is 2n = 4.

VI. Mutation A.Overview B.Changes in Ploidy - These are the most dramatic changes, adding a whole SET of chromosomes 1.Mechanism #1: Complete failure of Meiosis - if meiosis fails, reduction does not occur and a diploid gamete is produced. This can occur because of failure of homologs OR sister chromatids to separate in Meiosis I or II, respectively. - this results in a single diploid gamete, which will probably fertilize a normal haploid gamete, resulting in a triploid offspring. -negative consequences of Triploidy: 1) quantitative changes in protein production and regulation. 2) can’t reproduce sexually; can’t produce gametes if you are 3n.

Like this Blue-spotted Salamander A. laterale, which has a triploid sister species, A. tremblayi VI. Mutation A.Overview B.Changes in Ploidy - These are the most dramatic changes, adding a whole SET of chromosomes 1.Mechanism #1: Complete failure of Meiosis -negative consequences of Triploidy: 1) quantitative changes in protein production and regulation. 2) can’t reproduce sexually; can’t produce gametes if you are 3n. 3) but, some organisms can survive, and reproduce parthenogenetically (mitosis) A. tremblayi is a species that consists of 3n females that reproduce clonally – laying 3n eggs that divide without fertilization.