Sexual selection

Question 1

What is the red queen hypothesis?

Answer 1

A hypothesis suggesting that sexual selection and recombination is favored in shifting environments. All species are in evolutionary arms race with each other, and when the “rules of the game” are constantly changing it’s preferable for a population to constantly receive new genetic combinations, since it increases the likelihood for surviving the shifting environment.

Question 2

What is anisogamy and why has it evolved?

Answer 2

Anisogamy is the dimorphism is gamete size, where one gamete often is large and immobile while the other is small and mobile. The reason behind why anisogamy is not completely confirmed, but there are two major theories:
- - Gamete competition theory: suggests that anisogamy has evolved because there are different ways for a gamete to maximize fitness. The theory says that there is a fixed amount of energy and resoruces that can be allocated to gamete production  larger gametes leads to production of less gametes, while if you produce smaller gametes you can produce more

Question 3

What are the two alternatives in genetic sex determination?

Answer 3

Dominant factors or dosage dependent.

Question 4

What does it mean that genetic sex determination is dosage dependent?

Answer 4

Genetic sex determination can be based on dominance or dosage dependence. Dosage dependence is when the sex determining genes are located on the sex chromosomes present in both the heterogametic and homogametic sex (eg. the X-chromosome in humans). Since there is a disparity in gene product because of different number of X-chromosomes, the sex is determined by the amount of gene product produced.