Seaweed Revelations Part 2

I know you were all right on the edges of yours seats waiting to hear about the life cycles of seaweed so I will get right to the point. Here is also where I get to clarify things I learned way long ago but didn’t look at again because I’m not a botanist.

I know many of you are still reeling from yesterday’s revelation that algae are not and have never been a member of the Communist party Plant kingdom. But you’ll have to sit down and clutch your pearls again because I have more news (“news”). Now I must tell you that all plants and many algae display alternating generations. “What is that?” you ask, “Where did I get these pearls I am now clutching??” you exclaim. All will be answered in due time. The phrase ”alternating generations” indicates that the plants or algae alternate haploid and diploid generations. So one generation has double chromosomes (one set doubled, like you’re supposed to) the next has only half/one set of chromosomes (like gametocytes, that is, cells like sperm or eggs, are supposed to). So you have one organism with the appropriate number of chromosomes (2n, with n being one set of a given number) that produces spores to grow into ANOTHER organism with half the chromosomes of its parent (n chromosomes), which in turn produces sperm or eggs to help produce a new, diploid generation. The haploid generation producing the sperm and eggs may be a distinct organism or it may be closely associated/attached to its diploid parent (although subsequent diploid generations will not be). OK, this explanation is all well and good for biologists, but how can everyone else understand it?

First, look at this diagram:

LOOK AT IT.
This will give you an illustration of things to come.

 

Now stick with me for a very bizarre analogy. Imagine your reproductive bits are not an organ. You produced them, they are a part of you (they’re attached to you, anyway), but you can’t control them directly. They are their own entity. Creepy, huh? That is how MANY plants and algae function, they grow their haploid generation on the diploid generation. Now for the REALLY weird part: imagine those reproductive bits DO NOT remain a part of you. Once you have grown them, they live freely. That is how other plants and algae live. To summarize both: the children are like the sexual organs and the grandchildren are new organisms. This system seems confusing, but it does help weed out deleterious genes (haploid generations being more vulnerable to the effects of bad genes) while still allowing for either self-fertilization or non-self-fertilization (plants and algae can effectively mate with themselves or other, unrelated plants and algae). Advantages to self-fertilization would be preventing introduction of bad genes while non-self fertilization means the possibility of BETTER genes being introduced. Basically, all the options are still available, so it’s a win-win situation.

I hope that all makes some (albeit VERY WEIRD) sense. Let me know if it doesn’t. I’d like to do another algae-related thang, but I just had some projects come up so WE SHALL SEE.

 

Source

–. 2010. GRE Subject Test: Biology 5th Ed. Kaplan, New York.

 

Photo credit Pearson Education.

And Now For Something Completely Different…

Those “shameless little libertines” (periwinkles) are the tiiiny little snails you see covering rocks on rocky beaches. Shameless or not, they are adorable; scooting along the rock face and scraping algae off with their radula (a kind of tooth) like little gooey shelled cows. OK, yeah, they’re nothing like cows. But even their genus name is cute. Littorina. Of course, there are plenty of cute animals in the world, certainly cuter than one snail, so what is so special about Littorina? LUNGS. That’s right, amongst their rocky intertidal adaptations, besides a strong grip, shell and densely packed groups to resist water loss and wave shock, Littorina have LUNGS. Barring hypertonicity and dehydration, Littorina actually prefer life above water.

And now for something else seemingly completely different.
But I’ll explain soon.

Pop quiz! What is “polyandry”?
Is it:
A. A species of chiton
B. The little floaters on your eyes
C. A social system in which a female will acquire a male harem or mate with multiple males
D. Shut up, it’s summertime now quiz time!
E. Drag queen name

To everyone who answered C, you are correct! To everyone who answered D, cut the sass mouth, I will make you learn and assess your knowledge retention if I please.
Previously when I discussed polyandry, I pointed out the logistical problems of female promiscuity and caring/bearing offspring. However, sea horses proved an excellent example. Since the males carry the sea foals to term, the costs of polyandry on baby birthin’ are low. Dolphins, though followers of the fission-fusion social system, found another way that polyandry works. Female dolphins may not bear multiple calves by multiple males, but promiscuity ensures that the local males leave her alone as any of them could be the baby daddy. Trust me, this is a solid plan. If you had to deal with gangs of aggressive/randy/aggressively randy male dolphins on a daily basis, you’d get it.
Why am I rehashing polyandry? Because Littorina.
Monty Python didn’t know it at the time, but they were right about how fast and loose the Littorina play it. For each 70 baby brood, there is an average of 19 fathers responsible. The bigger the brood (or clutch), the more baby daddies. It’s pretty incredible that the lady Littorina can fertilize one clutch with more than one mate’s sperm, but WOW. Showing off maybe? Maybe. I’ve heard of increasing genetic diversity with multiple mates, but this is overkill. Over-fertile? Anyway, that’s a lot of mates. You would think that much business going down would get in the way. Or at least knock a gal off her rock. But the running theory is that dissuading all those ardent suitors would be more work and less reward then just going on with life. Scrape some algae, scoot about, mani-pedi with the girls…just ignore the impassioned fellow tagging along. Can you imagine? “I don’t know about this guy but…ehhh, asking him to leave sounds like WORK. Better not.”
Lazy little libertines.

Source
Marshall, Michael. March 24, 2010. “The world’s most promiscuous…snail.” Zoologger. New Scientist. June 19, 2013.
Yancey, Paul. “Rocky Shore- Abiotic Factors and Adaptations.” Marine Biology. Whitman College. Walla Walla, WA. 5 4 2011. Lecture.

Inspiration credit Paul Yancey.

NOTE: I do not, nor do I believe Monty Python does, approve of the gay-bashing featured in the video. Whelks should live however they please without fear of abuse. Seriously though, Monty Python enjoyed lampooning such behavior to point out its ridiculousness, but this was a bit much. Anyway, this is me awkwardly explaining the video was funny and relevant to recent scientific discoveries, and no offense was intended.

(A)Sexy Times

I LIVE! My statistics class is finished and I can write weird shit on the internet once more. Huzzah!

So let’s get right down to business. Not just any business, business, if you know what I mean. Right? RIGHT? Ya know…IT? The deed…? Sex. I’m going to talk about sex. Jeez, you guys are hard to fake talk to, may as well just talk to myself! Anyway, before the tittering (heh, “tittering”) begins, know that I will be talking about sexy times AND asexy times. That is, I’m comparing sexual and asexual reproduction. Bow chicka wow wow!

Now, although we’re waiting on input from single-celled organisms, plants* and…well, most animals, the consensus is that sex is pretty great. So that’s not a real consensus, sue me. But if you throw two sexually reproducing organisms in a room (maybe not actually throw them) and give them some alone time, they’ll make little sexually reproducing organisms and soon you’ll hear the pitter-patter of little genetically variable, possessive of good genes from both parents, feet. Independent assortment (Remember Mendel?) and random fertilization (the match up of different gametes with different chromosome combinations) makes for some incredible genetic variation potential. There are 8.4 million different chromosome combinations one gamete (sperm or egg) can possess, so that’s 70 trillion possible sperm/egg pairs, each with a unique combination of chromosomes. All the stuff about everyone being a miracle is true; each one of you was a one in 70 trillion chance. Unless you’re identical twins. Then you aren’t a miracle. You are a poseur.

All this variation means sexually reproducing organisms are (as a whole, not individually) completely prepared for environmental variability. They can evolve their way out of all kinds of shit. So sex is awesome! It results in genetic variability, the combination of good genes from each parent and word on “the street” is that it’s enjoyable, too. What’s not to like? EVERYTHING.

OK, maybe not everything, but the variation that makes sexual reproduction so good, can also be a big problem. Besides both parents contributing good genes, bad genes can also get thrown in and good gene combinations may be lost completely. In addition, it takes a lot of energy to find a mate and then reproduction is pretty slow. So what happens if you cut out the sex? Asexual organisms can reproduce by budding, division (only single celled organisms, but it’s funny to imagine koalas dividing) and parthenogenesis (two eggs mix in self-fertilization). Unlike sexual reproduction, the parent can pass on 100% of their genes and not worry about trying to get a date or bad genes from some lame baby daddy wrecking everything. Reproduction is also a lot faster. HOWEVER, without the genetic variability, asexual organisms can’t really handle variable environments, are susceptible to disease and can’t “lose” bad genes or gain better genes.

I say it’s a toss up. But HBO would be out of a job if we all went asexual, so may as well support the economy

 

Source

Bohn, K.M. 2011. “Sexual Selection”. Ecology. Whitman College. Walla Walla, WA.

 

*Yes plants have sex. Flowers are just colorful plant genitalia and “pollination” is just science slang for plant sex. Think about THAT next time you buy a bouquet for your sweetie.

Such lovely…flowers.