The Evolution of Sex - Causes n Consequences

Question 1

Sex

Answer 1

• Sex (sexual reproduction) is the combining and mixing of chromosomes during offspring production.
  
  • Meiosis and recombination
  • Fertilization
• Sex (M/F) is different from gender (non - binary)

Question 2

Origin of sexual reproduction

Answer 2

• Sex is common
• Life originated without sex so meiosis and sexual reproduction must have evolved
• There are disadvantages to sexual reproduction which makes the evolution of sex difficult to explain (“the paradox of sex”)

Question 3

Why have sex?

Answer 3

The fitness Cost of Sex :
- Only half of the sexual production can produce offspring

• The production of males leads to a “twofold cost of sex”
• Evolution should favour asexual reproduction

Question 4

Benefits of sex

Answer 4

1. Sex can remove deleterious mutations efficiently
2. Sex can recombine beneficial mutations
3. Sex results in more genetic variation - faster evolution

Question 5

Advantage of sex

Answer 5

• Sexual reproduction creates more genetic variations
• Allow for faster evolution - response to changing environmental
• Biological arms race: between hosts and parasites
  • Need to constantly outrun evolving parasites
  • Red Queen Effect

Question 6

Cost of sex

Answer 6

• Two fold cost of sex
• Search costs to find a mate
• Reduced relationship with offspring
• Risk of sexually transmitted disease

Question 7

Lack of sex

Answer 7

Some random ancestors abandoned sex 100 million years ago

• 400 species
• All female and daughters genetically identical to mothers

Question 8

Isogamy

Answer 8

Form of sexual reproduction, which involves the fusion of morphologically similar gametes, having similar shapes and sizes

Question 9

Anisogamy

Answer 9

Form of sexual reproduction, which involves the fusion of two dissimilar gametes, gametes differ in shape, size or form