Week10a+Summary


 * Question 1: What is a species? You**

[|Per5LeslyS] wrote: " A species is a group of organisms that have similar genetic characteristics to one another and are able to reproduce amongst each other with in that particular group of organisms." //And I will add - that means that two organisms that belong to different species cannot interbreed, or cannot raise fertile offspring.// **Question 2:** Using the links provided in teacherweb, search for an article that has to do with species formation. Key words can be as follows: Speciation, Isolating / isolation mechanisms. Under the link to your article write shortly:

[|Per2ChristinaM] wrote: A) The organism they are investigating are flycatchers, a type of bird.

B) The process that may separate them is behavioral isolation because the birds' colors change and cause a lack of attraction between ones of different colors.

C) "On the Road to a New Species" []

What I like about Christina's post here is her clear and simple description .of the way these birds separated initially, due to different color attraction.

Athough in each case the original group separated for different reasons, the principle is the same - separation for some reason for a long enough time, then staying more and more different over generations, to the extent that they can no longer inter-mate.

**Question 3: What makes you wonder about how species form, or how they genetically interacT? Write freely.** //Question 3 enables me to address some misconceptions:// "Sometimes I wonder how new species of animals are formed. I mean, I know how it generally happens. __Usually two different species mate to form a new one__. However, I wonder if these two species realize that they are different from each other. If they do, then how come they choose to mate with each other instead of their own respective species?" Oh, NO! Species, by defintion, never mate with each other. That is the whole idea. The hybrids such as ligers and mules exist mostly iun captivity, and are 'genetic dead ends', that is they are not fertile.

And then some interesting questions as well: "I find it interesting that so many species can develop. I wonder about how different species develop. Do they develop similarly or are there all kinds of causes? Do all species develop into others or are some unchanging? What kinds of things lead to changes?" Godo question! Answer is there are indeed all kinds of causes for speciation to begin. And probably there are species that have been the same unsplit group for a very long time. That shows how speciation begins with a random change, genetic or environmental, that cased initial separation.

" I always wondered why a variety of different species look very different, but in the inside, they are very similar. For example, we do not need a tail, yet we still have a bone for it. Should't it go away completely?" Great question (though not about speciation mechanisms) - You are describing what we call __'vestigial structures'__, and the answer is - yes, we have some structures that we don't need, but if they are not bothering us, there is no advantage or dosatvanages so we just still have these useless structures.

OK, I must stop here, but there are some great questions from you guys!