Bio 418 – Advanced Evolution
Week 5 Study Guide
Lecture Topics
(1) sexual reproduction
(2) selection 1: why sex?
(3) selection 2: sexual selection
Review:
Advantages and disadvantages of asexual & sexual reproduction
Causes and consequences of Bateman’s Principle
Interaction of male eagerness and female choice
Study questions and topics:
Define: asexual reproduction, parthenogenesis, Muller’s Ratchet, Red Queen hypothesis,
Bateman’s Principle, anisogamy, operational sex ratio, sexual selection, lek/lekking, direct
benefits, indirect benefits, nuptial gifts
Understand the evolutionary benefits and disadvantages of asexual reproduction.
Understand the evolutionary benefits and disadvantages of sexual reproduction.
What most commonly limits the reproductive rate of females? What about males?
How does sexual reproduction facilitate adaptation?
How does gamete production lead to an increased benefit for females to care for their offspring
as compared to males?
How is the operational sex ratio (OSR) different from the absolute number of males vs. females
in a population?
Explain why OSR is typically larger than 1.
How does the aggressive behavior of male elephant seals increase OSR beyond what might
normally be expected?
How would you expect increasing OSR to affect the strength of sexual selection on males?
What was the experimental evidence that led to the formulation of Bateman’s Principle?
In sexually dimorphic species, why are males typically colorful and/or ornamented compared
with relatively drab females?
How does Fisher’s runaway model of sexual selection explain the evolution of extreme male
characteristics?
How does the ‘good genes hypothesis’ differ from Fisher’s runaway model? What is necessary in
order to keep a ‘good genes’ signal honest?
What is the distinction between direct and indirect benefits?
How might a male trait provide both direct AND indirect benefits to a female?
What is a nuptial gift and is it considered a direct benefit, and indirect benefit, or both?
What explains the evolution of the male Australian redback spider’s tendency to willing submit
himself to sexual cannibalism?
Why do you think monogamy rarely occurs in nature?
How are polygamy, polygyny, and polyandry related to each other? Which one of these
contradicts Bateman’s Principle and why?