The workings of natural selection Some examples in nature

How Does Natural Selection Work? Survival of the fittest? What is fitness? Being: big? fast? Strong? beautiful? Rhinoceros beetle Blue Whale Cheetah

Then why do small, slow, weak, and ugly animals exist? Because fitness is simply the ability to live long enough to pass on as many genes as possible. A variety of qualities can be adaptive (fit) depending upon an organism’s environment. That environment includes other living things, including members of the same species.

What’s for Dinner? Are these insects easy to see?                                Are these insects easy to see? If you were a bird would you try to eat one of these insects? Why?

Harmless mimics need unpleasant models. How do obvious, yet harmless insects survive?   Robber fly Bumblebee Harmless mimics need unpleasant models. Flower fly I’ll have a taste Honey bee Conopid fly Wasp

Do the math The models must out number the mimics so the negative reinforcement is more common than the reward. Better not take the chance

The signal must be consistent Looks like trouble

Did you know that some birds dance? Crazy, beautiful birds Have you ever wondered why there are so many colorful birds and why they sing? Did you know that some birds dance? Fitness includes passing on genes. If an animal can’t find a mate it won’t reproduce. The male bowerbirds shown above build and decorate structure to attract the females – just like peacocks. Only 5% of the males get to breed with all the females.

Does this mean you have to be bold to mate? Meet the side-blotched lizard – AKA the “rock, paper, scissors” lizards Rock – Orange throat, aggressive w/ large territory & many females in harem Paper – Blue throat, defends small territory, 1-2 females Scissors - Yellow throat, no territory, sneaks around and mates with females from the harems of other males Each type of male exists because their strategy works, the orange are the most common and the yellow are the least. Any idea why that is?

Competition & deception is not the whole story cooperation can be a very successful strategy as well. Do you remember how mitochondria & chloroplast became part of the eukaryotic cell? These leaf cutter ants are all related and cooperate to: find food, tend the young, and defend the company. Did you know that they don’t eat the leaves? The grow fungus on the leaves and eat that. These ant may be the Earth’s 1st farmers.

To Summarize natural selection Natural selection is more complex than a simple competition for food resources. There are different aspects to selections: Sexual selection - because mates are resources necessary to pass on genes Kin selection – helping a closely related individual survive & breed is equivalent to breeding yourself. Co-evolution –Some survival strategies are dependent on others – the mimic needs the model Ecosystems - are complex, there are many successful survival strategies in nature.                                For your summary: find a specific example (not on this PowerPoint) of sexual selection, kin selection and co-evolution and name the organism(s) involved and explain why it is and example of that type of selection.