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Plant Sciences, Zoology & Evolution / When does evolution turn "choice" into speciation

« on: 21/09/2011 10:56:15 »

I watched a doco last night about evolution called Mutant Planet Africa.  It focused onThe Grift Rift Vally where it was highlighted that the cichlids fish split into 500 species in a relatively short period (12,500 year old lake). 

They described how this speedy evolution may have occurred. e.g  where some female fish may have preferred a male fish that built sloping mounds on the lake floor and avoided other males that built flat mounds.  The female then breeds with the sloping mounded males.  In turn, the female's offspring is most likely to prefer sloping mounded males, and may never breed with the flat mounded males.  The narrator explains that this situation can start a new cichlids species.

Now to my question.  It seems to me that although the female fish has preference for sloping mounds, I don't see how that can lead to speciation.  My logic is that even though she chooses/prefers sloping mounded males, she is still biologically able to breed with the flat mounded males and have offspring.  When does this "choice" cross the line into creating a new species that is not able to breed with the old species?

Sorry for the rambling, and if i'm not making any sense! Thanks,

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General Science / Can telescopes view the same object in space at different points in time?

« on: 17/03/2011 14:47:59 »

Dear Naked Scientist and forum goers
I've been fascinated in science and astronomy for a while now but this question has always been in the back of my mind.  I don't remember it being mention yet so here goes..
I've been told that telescopes are like time machines eg. The further it penetrates space, the further back in time it can observe.  I know this is simplifying the process a bit, but if this is true, is it possible then to view the same object e.g a relatively nearby supernova, magnify the telescope to go further back to a time where the the same supernova was still an unexploded star and observe it in this state?
Thanks in advance and keep up the great work!