Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: ConfusedHermit on 18/08/2012 05:35:56
-
I understand the concept of organisms procreating, mutations occurring, and whatever traits happen to survive are the ones that get passed on to the next generation, but the snail confuses me a little.
What exactly did snails adapt to overcome by merging the two sexes into one?
Or were they always hermaphrodites?
If that's the case, would they go extinct if there were only male and female snails, as they would no longer be able to clone themselves via self-fertilization?
If any organism is threatened by not finding a mate in time, could the trait of hermaphroditicism form and potentially persist in a 'one male and one female' species--because survival means everything?
I ask this because civilized humans seem to have had less trouble finding mates compared to most things in nature, which may add to why the rare instances of hermphroditic humans don't have fully functioning reproductive organs (all of them, though I've read one might work) because we haven't evolved to work that way.
-
What exactly did snails adapt to overcome by merging the two sexes into one?
Or were they always hermaphrodites?
I think they have always been hermaphrodites ...
Scientists believe that before the two-gender state that most animals, plants, and fungi now find themselves in, there was only one sex, and everybody could mate with everybody else.
http://news.sciencemag.org/sciencenow/2004/10/06-04.html
If any organism is threatened by not finding a mate in time, could the trait of hermaphroditicism form
The only thing close to that I'm aware of is parthenogenesis (virgin birth) ...
The switch between sexuality and parthenogenesis in such species may be triggered by .... a lack of males
https://en.wikipedia.org/wiki/Parthenogenesis#Life_history_types
-
Oh yeah, I've heard of parthenogenesis :{o~ ...
So... Is the question 'why are snails hermaphrodites' something we can't answer, except that it was just how they evolved?
In that link about how there used to be one sex and it was evolutionarily superior to have two sexes, what does that say about snails? Are they STILL that 'one' sex from back then, or was that something you couldn't even call a hermaphrodite at the time? If two sexes are better, how have snails lasted?
I wish I even knew what they meant when I say 'back then.' Hell, there were male and female dinosaurs, so when was this 'two sexes' thing a 'new' thing? :{O~
-
Snails have been around for a long time (https://en.wikipedia.org/wiki/Cambrian), they’ve seen the dinosaurs come and go, so snail's two-sexes-in-one-individual method of reproduction is evidently very successful.
Specializing into individuals of different sexes with different roles, e.g. where one gives birth and looks after the kids and the other brings home the bacon and defends the family (genes (https://en.wikipedia.org/wiki/Gene-centered_view_of_evolution)) from predators, must only be advantageous in certain environments, (e.g. one where there is a long childhood (http://www.americanscientist.org/bookshelf/pub/the-benefits-of-a-long-childhood) ).
I’m not sure how you define “evolutionary superior” other than being populous and having existed for a long time, (snails have got humans beat on both counts). Complexity/Intelligence is not necessarily a measure of evolutionary success as a great many species more intelligent than snails have gone extinct during the 500 million year era of snails.
It’s anthropocentric to consider animals less intelligent than ourselves to be inferior, ( particularly when, based on past performance, they will probably see us out ).
-
There does not seem to be a huge generic advantage or disadvantage to have both sex in one organism or separated in two.
In plants having both sex in one organism is the default. However, having both sex in two different organisms (dioecy) appears in nearly random over the whole kingdom of plants. It is quite common that you have dioecious and monoicous within the same family and sometimes even within the same genus. So at least in plants it seems to have evolved forth and back maybe dependent on environment.