Evolution of Sex, part 2 Updated 1/29/2024 (This chapter is really just a lot of vocabulary)
• What are the differences between sexual and asexual reproduction?
• With respect to sexual reproduction, know the following vocabulary: gametes, diploid (2n), haploid (1n), zygote, sexual dimorphism
• What is isogamy and anisogamy?
• What is the difference between gonochoristic versus hermaphroditic?
• What is the difference between a simultaneous hermaphrodite versus a sequential hermaphrodite?
• What are some examples of sequential hermaphrodites and simultaneous hermaphroditic given in lecture?
• Know that gametes (eggs and sperm) are haploid (23 individual chromosomes), while all other body cells (somatic cells) are diploid (23 pairs of chromosomes).
• With respect to human chromosomes, what are autosomes versus sex chromosomes?
• Know sex determination in humans (percent girls versus percent boys) by inheritance of sex chromosomes (see punnet square in PowerPoint) Added 1/29/24
• Know that bacteria reproduce primarily by asexual means (cloning, known as fission) but evolved the ability to exchange genetic material with other bacteria through bacterial congjugation.
• Under Cloning, what were different examples of organisms that reproduce by cloning:
- bacteria (fission), yeast (budding), Whiptail lizards in New Mexico (parthenogenesis), viral replication, fragmentation, and artificial cloning done by scientists on mammals. What are monozygotic twins?
• What are the 4 F's associated with the limbic system? (this could be short answer question)

Advantagse vs Disadvantages of Asexual Reproduction (I will ask short answer questions on advantages of asexual reproduction, where you must list them, and some multiple choice questions on disadvantages!)
Advantages:
1. No male & female gametes to combine (no searching for mate)
2. Offspring is genetic clone to parent (100% genetic contribution)
3. Avoids the two-fold cost of sex [1) can produce more offspring faster, 2) no males that cannot give birth]. Who came up with concept of 2-fold cost of sex? (> John Maynard Smith)
4. Desirable traits not diluted (50%) by a mate's contribution
5. Guaranteed chance to reproduce
Disadvantages:
1. Less genetic variation in offspring (poorer quality offspring), which leads to inbreeding depression
2. Cannot evolve (adapt) to new environments, which makes one
3. Vulnerabe to environmental changes because clones have no new source of genetic variation.
4. Undesirable traits (like diseases) not diluted by a mate's contribution
5. Without source of new genes, mutations build up in population and can lead to mutational meltdown, and extinction of the species.

Advantages vs Disadvantages of Sexual Reproduction (I will ask short answer questions on disadvantages of sexual reproduction, where you must list them, and some multiple choice questions on advantages of sexual reproduction, including who came up with the hypotheses!)
Advantages: (the 3 hypotheses for why sex exists and persists, and who came up with them)
It provides source of genetic diversity!
1.Tangled Bank Hypothesis (Williams and Ghiselin)
Offspring have enough genetic diversity from parents to exploit new niches/adapt to environment so as not to compete with parents.
2.Red Queen Hypothesis (Hamilton and VanValen)
Sexual reproduction provides the genetic diversity that allows our immunity (defenses) to stay one step ahead of parasites and pathogens.
3. DNA Repair Hypothesis and hybrid vigor. (Mueller)
Sexual reproduction between parents with different DNA (are unrelated to each other) produces offspring with higher genetic diversity in which the effects of bad mutations (diseases and disorders) are reduced.This avoids "inbreeding depression" and is why most cultures have an incest taboo.
• What were the examples of autosomal recessive disorders (that increase in frequency due to inbreeding depression)?
- Ellis-Van Crevels Syndrome
- cystic fibrosis
- Tay Sachs
Disadvantages:
1. Recombination destroys adaptive combinations of genes (if your genes were already great, they get diluted by mate's contribution).
2. Only 50% genes inherited from each parent.2.
3. Has the “Two-fold Cost of Sex”[which means 1) sexual reproduction is a slow process and it produces fewer offspring over time, and 2) it produces males, which cannot themselves bear offspring.
4. Males & females must find each other to reproduce.
5. Egg usually stays put (in female) while sperm must move, find, and compete for egg entrance.
6. Involves "being at right place, right time" -evolution of reproductive cycles. (There might be
7. Brings in complication of competition for access to mates.(You might not be guaranteed a chance to reproduce.)
8. Complicated by "female choice"into mating (females are choosy when selecting mate)
9. There is an imbalance in cost of cost of sex between males & females. Females bear greater cost than males (espcially in humans). Females produce fewer eggs than males produce sperm. Pregnancy and childbirth are energetically expensive, and has dangers.
10. This imbalance in cost of sex between males and females leads to “different reproductive agendas for females and males”. [often these strategies conflict w/each other]
11. The Y chromosome is shrinking

PBS Essay Online Reading Assignment: Why Sex - The Advantage of Sex
• Who is credited with first coming up with the Red Queen Hypothesis?
• What is heterozygosity? Why can it be an advantage in terms of disease?
• What is the empirical "real-world" evidence for the Red Queen Hypothesis described in this article? (i.e, the "best test of the Red Queen Hypothesis"), and what organism was used to support the hypothesis? - pg 4 of reading

Biology of Beauty (with the loss of a lecture last, we obviously did not get to this material, so it won't be on the first exam.)
• What is the difference between the "reproductive agendas" of males versus females? (what are men looking for versus women)?
• What were some animal examples given in lecture of where males are choosy because they bear a greater cost in reproduction (they get pregnant)? (male seahorses and pipefish)
• What are the 5 Universal Ideals of Attractiveness for men versus women, as discussed in class?
• What is bilateral symmetry?

• What are some of the experiments outlined in lecture that support the basis of symmetry as a strong attraction for animals (including humans)?
- Thornhill (studied male scorpionflies and found that females chose overwhelmingly chose more symmetrical males as mates than less symmetrical mals.
- Thornhill & Gangestad (studied college students with a questionnaire and a diary, and by measuring their facial symmetry, and found that more symmetrical men had sex 3 - 4 years earlier than less symmetrical men. Symmetrical men and women had greater number of sexual partners, and reported less illness compared to less symmetrical students.
- Maria Sancho-Navarro studied facial symmetry in male college students, had women rank them by how attractive they found them, and studied the semen quality in the male participants. She found that the men the women ranked as most attractive (based on symmetry) aslo had the highest quality sperm (best sperm shape and motility). See Handsome Men Have the Best Sperm reading assignment.

• What are the effects of testosterone on males versus estrogen on females after puberty that affect secondary sexual characteristics that are deemed "beautiful" to the opposite sex? (I will have 2 short answer questions on this, where you must list them!)
• What is the significance of the male beard in attractiveness? What signals can a beard send to women? What is frequency dependent selection, with respect to beard length?
• What is the waist-to-hip ratio? Who was credited with research on the topic?
• What are the ideal male and female waist-to-hip ratios?
• How does a male's reproductive ROLE differ from a female's? (4 things for men and women covered in class)

Biology of Beauty Reading Assignments: (I've narrowed it down to these)
The Biology of Beauty - by Geoffrey Cowley
• What are some of the "honest advertisements" based on exposure to androgens (testosterone) in males versus exposure to estrogen in females? [pg 5 of reading]
• Who is the researcher that studied WHR in women using Playboy centerfolds? [pg 6 of reading]
• What did the MHC T-Shirt Test demonstrate about women's sense of smell and MHT in males? What does that have to do with hybrid vigor?

Handsome men have the best sperm
• What researcher studied how semen quality is correlated to ratings of male "attractiveness" and best sperm morphology?

Beards: Too Hip for Their Own Good
• What did beard researchers discover when they showed women photos of men having different levels of "beardedness"? What is frequency-dependent selection?

On this site I will post supplements that will help you learn material from lecture. These supplements will be posted with each chapter covered and might include practice quizzes, interactive exercises, review material, and relevant examples to material covered in class.