Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Types of Sexual Selection
Document related concepts
Transcript
Evolution Note #11 SBI3U – Sexual Selection “The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!” – Darwin The Peacock Problem - Darwin could not understand why peacocks would evolve such huge _________________ ___________________ Wouldn’t these long tails be a hindrance? o Attract more _______________________ o Make it hard to move around o Require a lot of ___________________ Not so much a problem… - Peacock tails are not adapted to an _____________________ Peacock tails are adapted for _____________ __________________ Female peacocks (peahens) are attracted to more elaborate peacock tails Males with more elaborate tails are more likely to ____________, are more likely to have offspring and, therefore, the trait for elaborate tails will be continued through the population Sexual Selection Sexual selection – the ___________________ of any trait that specifically enhances the _____________ ________________ of an individual - Sexual selection leads to features that don’t help an individual ______________, but enhances their ____________________ success Types of Sexual Selection Intrasexual selection – selection based on “___________-________ __________________” Intersexual selection – selection based on “__________________ _________________” Intra-sexual Selection – “Male-male Competition” - Males often fight amongst themselves for access to _______________________ Leads to large sixes, extraordinary fighting ability, or elaborate “weapons” Male-male selection may be selected for since the offspring of these “strong” males will also have genes for strength, dexterity, etc. List two examples: Intersexual Selection – “Female Choice” - The Peacock Problem Why would peahens choose to mate with males with more elaborate tails? Elaborate traits can indicate ______________ or _________________ of a male o Fighting ability Evolution Note #11 - o Ability to avoid predators Elaborate traits can tell a female a lot about the ________________ of a male o A greater resistance to disease or parasites o An efficient metabolism Intersexual selection has lead to some of the most interesting features and behaviours of organisms. List two examples: The Widowbird Experiment - - Long-tailed widowbirds live in __________________ The males have incredible long ___________________ Females are dull and brown Researchers changed the ___________________ of males birds tails by either cutting them to make them shorter or by gluing more feathers on them to make them longer Found that males with artificially elongated tails mated more The researchers often _________________________ the tails to make them longer than they grew naturally The females __________________ this “unnatural” trait Could this lead to the evolution of even __________, more hindersome tails in the Widowbird? Irish Elk Irish Elk - Extinct deer species Had immense ______________________ Such large antlers may have caused its extinction because the antlers were too _________ and it couldn’t adapt fast enough to the changing environment
