Alage Eaters?

[elisabeth]

Um, the question is how many snail eggs will survive! Oye, why is it that the snail reproduces, and the stupid newts aren't gettin it on??? It's just annoying!

 

[kaysie]

elisabeth, thats because snails are hemaphroditic, and can reproduce by themselves, and sadly, newts cant.

i'm betting a lot more than one snail egg hatched, you just havent found them yet. or they've already been eaten.

 

[jesper]

Hi all!
I wouldnt house any fish with newts, I have read about newts hurting themselves by trying to eat algae eaters

I have also read about big algae eaters attacking small newts apparently they eat other things than algae...

These things often happens after years of peaceful cohabitation, lets call them misunderstandings...

Dont trust fish!

Elisabeth: You must have greedy little newts, when my snails are "at it" I usually find dozens of miniatures a while later.

I say "at it" because even though most snails are hermaphroditic, they usually can not self-fertilize:

"A snail's fertilization by itself mostly is prevented by the development of sperm and egg cells, which, passing hermaphroditic areas of the genital apparatus are unripe and ripen only when those areas used by male as well as female genital cells are passed. Besides self-fertilization is not feasible, as it not provides a mixing of genital information and so to the greatest extent hinders variation. Variation on the other hand is one of the most important motors of evolution. Organisms reproducing solely by self-fertilization (parthenogenetically) have a very low variation only based on mutations occurring during the embryonic development. That is why most species, that reproduce parthenogenetically, at another time of their life also reproduce sexually "

 

[elisabeth]

Yeah, well Jesper, I hope they are greedy. I only really need and can house one snail.
And my newts have gone at it, but I'm not sure if it took. How soon will I be able to tell if the female is gravid?

 

[jesper]

BTW I have been reading posts about snails that poop a lot, I say this:
More goes in than goes out since the snails grow which means that snails do not produce waste at least not more than they consume. By the rate my snails grow I would say they consume a lot more than they produce.

Snails are good fish are bad!

 

[samuel]

Jesper, self fertilization DOES offer genetic variation via the random fussion of gametes. However it is the most severe form of inbreeding and does hamper genetic variation but nevertheless it still does offer some genetic variation.

Btw, about the snail poopoing, it does make sense. But i'm worried if the snail poop might harm the newts if accidently ingested during feeding.

 

[samuel]

And i dun think self fertilization=parthenogensis. The former involves the fusion of gametes while the latter involves embryonic developement from a haploid or diploid secondary oocyte.

 

[samuel]

sorry again, haploid secondary oocyte. Diploid eggs are fromed via mitosis but the haploid eggs are formed via meiosis.

 

[jesper]

Yep Sam, you are absolutely right!
I just copied the text(not mine!

) to support my statement that snails usually breed sexually not by self-fertilization. I read through it way too fast - It is not a good text....

The self-fertilization takes place when two gametes melt, these gametes(haploid) are indeed formed by meiosis. When two gametes melt together a process called recombination can take place. This happens when bits of DNA are partially identical and change place.

Parthenogenesis is another phenomenon where a gamete(haploid) doesnt have to melt together with another gamete but can duplicate the one setup of chromosomes it has(I have no clue how).

As far as I know an oocyte(eggcell) can only be haploid(from the start), If it would be diploid there would be no need of any fusing. However during parthenogenesis an oocyte obviously becomes diploid, but I have never heard of an oocyte produced by mitosis - on the other hand I am not a biologist

 

[samuel]

Some species of animals perform haploid parthenogenesis where the haploid egg developes into a haploid adult (bees and some ants). Usually the male is haploid and the female is diploid. The diploid female is due to normal fertilization while the male is due to parthenogenesis, both forms of reproduction in the same species! Facinating! Hehe Jesper, i'm not a biologist too, the stuff was gotten from my lecture notes.

 

[jesper]

Oh, so parthenogenesis doesnt involve duplication of the single set of chromosomes? That solves the riddle! Yep, really fascinating that the male bee can live as a haploid when the female is diploid, explains why males have shorter lifes in these species - haploid=expendable

 

[kaysie]

Sam, thats not true in the majority of the cases. the female of the species is the one who reproduces, she makes the eggs. if these eggs are haploid, they must be clonal of her, and the haploid is the female, and the diploid is a result of mating, and may be male or female. there's a species of lizard (i forget which one) which is entirely female, and reproduce by parthenogenesis. they're all female because the oocytes are clonal of the original female.

the best thing: not all sexual inheritance is like it is in humans. in humans, you receive an XX and you're female, or an XY and you're male. in birds, this is the opposite, the XY makes female. or in some lizards, there are no males at all!

 

[tara]

Kaysie
Sorry but you are the one who is wrong in this case
"Workers of social insects may enhance their inclusive fitness by laying unfertilized eggs that develop into males. "
From
LAURA WALIN et al. (1998). Worker reproduction in ants a genetic analysis. Heredity
Volume 81 Issue 6 Page 604.


For more detailed info see the following linkhttp://news.nationalgeographic.com/news/2003/09/0908_030908_beegene.html#main


(Message edited by edwardst on December 05, 2003)

 

[samuel]

The stuff i said applied only to social insects, that's why i disclaimed myself by stating only the examples of ants and bees which are social insects. Like Tara stated, the unfertilized haploid eggs develope into males while the fertilzed diploid eggs develope into females. But Tara, i never knew that the workers can lay eggs. too... The drones i thought were only formed by eggs laid by the queen.

Yes, Kaysie i read about the diff sexual inheritance in my notes too but not too indepth, as i say it is very facinating, the common blind snake also reproduces via parthenogenesis.

The haploid eggs laid by the female cannot be clonal of her. This is because... 1. the eggs are haploid and the female is diploid, how can they have the same genetic information? 2. Genetic variation has already been introduced during the stages of meiosis that results in the formation of the haploid egg (5 stages of genetic variation). The formation of the haploid egg is sexual while the parthenogenesis bit u mentioned about the lizards is asexual (diploid parthenogenesis to be exact, the female lizard lays diploid eggs formed via mitosis which develope into female clones) hence u cannot use the latter example to support the formal.

 

[jesper]

Geez, obviously I know nothing of different breeding systems.
A diploid oocyte via mitosis?? Cool! Should it really be called oocyte then?

Cheers
/Jesper

 

[samuel]

Err.... haha, that i dunno. Maybe no. But it is a totipotent (maybe somatic?) cell that would develope into a clone of the parent.