College Questions Part 2

Hello everyone once again!


I have to do a powerpoint presentation in Biology about "Speciation" I wanted to use Native fishes and inform my audience about the difference in species and how hybridization occurs in the wild. Why is it that these hybrids make it through reproductive maturity and why is there no hybrid inviability when it comes to certain Sunfishes.

I am not looking for anyone to do my homework.

I am here to ask if anyone can point me in the right direction in terms of books or web sites links that I can look at to better help me make this accurate presentation to the class.

I was looking to do my speciation presentation on the hybridization of Sunfishes in the wild. Do you guys think this is a good topic for a a brief 6-10 slide power point presentation about Species?

Thanks

I would start out by elaborating on what you define as a species - Chris did a great synopsis of species concepts in A/C a couple of issues back.

As for the rest, I'll let the Cichlid - er, I mean Sunfish - guys point you to their favorite resources.

Hybrids. Sigh... It's OK, you couldn't have known...

I can't help you on the hybridization part other than by say the "speciation" isn't so complete as to have made all the genetic changes required to make them true 100% separated "species." The whole species thing is a little cloudy. You could look at speciation on a temporal (like geologic time) scale along with realted isolations and dispersals. Most of the fish in New York are relatively recent invaders since the last ice age. Generally the hybridization is not a big mover in speciation. Google "endemism freshwater fish." Or something along those lines. You'll get a gist of the factors leading to speciation in NA fishes. Ice ages played a big role in it all.

One theory you might want to use is that over time, separated fish will become new subspecies, species, subgenera, genera... orders, families and so on. Th relatively recent radiation of the extant sunnies means they can still produce viable offspring. Give them some Time, and they eventually will not be able to breed given the right set of factors. An idea is to compare these relatively recently radiated fishes with others that are split from an ancestor further back in time that can't cross with their related species or genera. You could also find a good cladogram of sunfishes and check on the viabilty of crosses that are more distantly related. How big a presentation do you want this to be?

I would start out by elaborating on what you define as a species - Chris did a great synopsis of species concepts in A/C a couple of issues back.

As for the rest, I'll let the Cichlid - er, I mean Sunfish - guys point you to their favorite resources.

Hybrids. Sigh... It's OK, you couldn't have known...

Well I am trying to do my own research but it is a little difficult since Im not to familiar with many of the scientific words. Hopefully any sunfish experts here can help me out when they have a chance.

I can't help you on the hybridization part other than by say the "speciation" isn't so complete as to have made all the genetic changes required to make them true 100% separated "species." The whole species thing is a little cloudy. You could look at speciation on a temporal (like geologic time) scale along with realted isolations and dispersals. Most of the fish in New York are relatively recent invaders since the last ice age. Generally the hybridization is not a big mover in speciation. Google "endemism freshwater fish." Or something along those lines. You'll get a gist of the factors leading to speciation in NA fishes. Ice ages played a big role in it all.

One theory you might want to use is that over time, separated fish will become new subspecies, species, subgenera, genera... orders, families and so on. Th relatively recent radiation of the extant sunnies means they can still produce viable offspring. Give them some Time, and they eventually will not be able to breed given the right set of factors. An idea is to compare these relatively recently radiated fishes with others that are split from an ancestor further back in time that can't cross with their related species or genera. You could also find a good cladogram of sunfishes and check on the viabilty of crosses that are more distantly related. How big a presentation do you want this to be?

Well I have exactly 5-10 minutes and I need to present 6-10 slides with pictures and words. I wanted to explain hybrid inviability and hybrid sterility, but I dont want to use the good ol' mule horse and donkey thing. I want to use NA fishes! lol

So I need to briefly explain mechanical isolation and behavioral isolation and inviability and sterility and I want to use Native fish as my focus on the presentation. I need to know what happens though, when the bluegill and green sunfish mate and create hybrids, are those hybrids fertile? Can they produce offspring with other hybrids or only with the parental bluegill or green sunfish? I read that the hybrids tend to be 95 % males , is there a reason why so many males are born and not to many females???

In any case thanks for the info, Im gonna do some further research on this stuff.

Do you have access to JSTOR or any other journal databases? You could probably find some papers there. Even Google scholar might have something. We ran into a mess of hybrid sunfish last weekend in the San Gabriel River. You don't see them too often, so it was strange to see such high rate out there. There were longear, greens, bluegill, and redears-most pure, but plenty mixed up. We field id'd the pure ones and kept the hybrids. I need to go look at them again, and pass them around and see what we come up with.

Edited by rjmtx, 20 March 2008 - 09:38 PM.

ChannelCat,

One thing that might help people help you - is this for a college, high school, or middle school biology class?

Others are much more expert than me on speciation, but there is more to it than just sterility. Basically, species have to be genetically isolated from each other - that can be because they can't breed and produce fertile offspring, OR it can be because of geographical isolation, OR, they could live in the same habitat but they naturally breed at different times or in different ways. So, if the different sunfish species evolved in areas where they were genetically isolated from each other and were then suddenly put together (as is the case when people stock them in ponds), this isolation is artificially removed and fertile offspring might be produced. Another example would be if two species live in the same lake but one spawns in the early spring and one in the summer, but if we were to artificially fertilize the eggs they might produce fertile offspring. Someone please correct me if I'm wrong here...

Have fun with your project - it sounds like a good one! Good for you for going beyond the horse/donkey thing.

ChannelCat,

One thing that might help people help you - is this for a college, high school, or middle school biology class?

Others are much more expert than me on speciation, but there is more to it than just sterility. Basically, species have to be genetically isolated from each other - that can be because they can't breed and produce fertile offspring, OR it can be because of geographical isolation, OR, they could live in the same habitat but they naturally breed at different times or in different ways. So, if the different sunfish species evolved in areas where they were genetically isolated from each other and were then suddenly put together (as is the case when people stock them in ponds), this isolation is artificially removed and fertile offspring might be produced. Another example would be if two species live in the same lake but one spawns in the early spring and one in the summer, but if we were to artificially fertilize the eggs they might produce fertile offspring. Someone please correct me if I'm wrong here...

Have fun with your project - it sounds like a good one! Good for you for going beyond the horse/donkey thing.

Yeah its a college Biology class. I am going to look into that information you gave me and some other information I got and see if I can formulate a pretty good power point presentation. I just need a little more info on when these sunfishes breed and some better pics to put on the power point.

Thanks everyone for your on-going support!