{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

1323440975_CHAPTER11_SPR

1323440975_CHAPTER11_SPR - EVOLUTION/LECTURE1 Evolution(PCB...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
EVOLUTION/LECTURE1 file:///E|/CH11-SEX-SELEC-SPRING-2008/CHAPTER11_SPR_2008.HTML[12/8/2011 2:54:36 PM] Evolution ( PCB 4674 ). Chapter 11. Sexual selection Main topics of lecture: 1.- Sexual dimorphism - Charles Darwin contribution 2.- Asymmetries in sexual reproduction 3.- Male-male competition: Intrasexual selection 3.1.- Combat 3.2.- Sperm competition 3.3.- Infanticide 4.- Female choice 4.1.- Gray tree frogs 4.2.- Choosy females may get better genes for their offspring 4.3.- Choosy females may benefit directly through the acquisition of resources 5.- Diversity of sex roles 6.- Sexual selection in plants 1.- Sexual dimorphism - Charles Darwin contribution 1.1.- Males and females are often strikingly different in size, appearance, and behavior. These differences between the males and females of a species is called sexual dimorphism. In this lecture we ask why sexual dimorphism occurs in such a great variety of organisms. It is a question Charles Darwin wrote half a book about!!! 1.2.- Differences between sexes are not adaptive. They do not help to improve the survival of fecundity of the individuals that possess them. For instance males of widow birds have long tails. If they can improve the survival and fecundity of a widow bird, then why do only the males have them? In many aspects we would expect that long tail feathers probably make male widow birds easier for predators to find and catch. In addition growing long tail feathers requires considerable energy. 1.3.- Sex provides a solution to the puzzle of sexual dimorphism. The two main challenges of organisms are to survive and to reproduce. For organisms with sexual reproduction this means that they have:
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon