For whatever reason. this Q just popped to mind (or what’s left of it)?
Since the tiniest bugs/promitive flora have developed some varient of sexes, what is left in the DIY-type reproduction?
is asexual limited to single-cell plants/animals?
And, once this has deteriorated into joke posting, a second Q (my favorite for self-described biologists, et. al.):
What is the difference between plant and animal?
First round disqualification: single cell
Second: fungi (no chloroplasts).
If you want to include parthenogenesis as asexual, then lizards and avians fit the bill (hee hee.)
Que? Fungi are not plants… 
I would have to say the biggest difference between plant and animal is in ancestry - plants are all descended from ancestors that performed their own photosynthesis, while animals are not. The difference between fungi and animals is all rooted in ancestry as well. Functional characteristics like photosynthesis are not great ways to define phylogenetic categories of organisms (they are OK for ecological categories of organisms) - algae are also all descended from ancestors that performed their own photosynthesis and so are the cyanobacteria.
Yeah, komodo dragons have been known to reproduce via parthenogenesis.
Not the largest, but an interesting example is the budding of hydras: they simply grow small hydras on their bodies, which then break away. (Interesting fact: hydras do not seem to age and are, by some, assumed to be biologically immortal.)
There’s also reproduction via fragmentation, where the parent is split into parts (or sheds a part/parts), which then develop into individual organisms – starfish are able to do that, and it’s reasonably common in the plant kingdom.
Also, turkeys can, sometimes, produce fertile eggs without a male.
Cecil on parthenogenesis: http://www.straightdope.com/classics/a991008a.html
Sharks have been known to do it, too.
Clay Aiken.
I learned about this one from a Dave Barry column – the creature Symbion Pandora, which lives parasitically on lobsters, has a very weird life cycle, and can reproduce both sexually and asexually:
Unfortunately, what made it memorable in Dave Barry’s column – (“This is a creature that reproduces by pooping!”) – is actually the not entirely accurately described) sexual mode.
But it’s still a weird creature in a new phylum, and a multicellular asexual reproducer.
Many plants can reproduce asexually. A grove of aspens could be considered a single organism (genetically the same, anyway). Aspen groves can be very old – thousands of years old. Someone correct me if I am wrong, but I recall reading somewhere that an aspen grove held the record for oldest living organism.
I believe that, technically, the largest organism in the world uses asexual reproduction. It is an enormous fungi living under many square miles of some forest in Oregon (?). Although its “body” is composed of microscopically thin filaments, it is spread over such a large area that if you put all these filaments together it would be the largest living thing on earth. And most fungi are capable of reproducing asexually.
So maybe the biggest AND oldest living things use asexual reproduction.
Birds, really?
Does this mean that every so often a chicken will lay some fertile eggs even if the rooster hasn’t been around in weeks? When does parthenogenesis in birds occur, and is it limited to certain species or families?
…Even educated fleas do it; Let’s do it, let’s…er…bud off.
Kinda ruins the lyric, actually.
Parthenogenesis is asexual production, but in species that are either normally or deprecated sexually reproducing animals. Most parthenogens are heterogamous; that is, they’ll reproduce by parthenogenesis is necessary (i.e. a lack of males) but will otherwise reproduce by normal means rather than budding or utero-cloning; however, a few insect species have completely done away with the male gender and reproduce exclusively by parthenogenesis. On the other hand, there are a wide range of highly prolific primitive plants that reproduce by apomixis. (This does not include self-pollinating hermaphroditic plants, which have diploid or polyploid chromosomes and reproduce “normally”, by haploidisation and recombination.)
Sexual reproduction is such a tremendous benefit in terms of the wide range of variation that unless a species is very prolific in comparison to other species it is in direct competition with, the sexually reproducing species tends to adapt better and win out; the larger and less specialized the species is, the greater the advantage from sexual reproduction. On the other hand, there are some major difficulties with sexual reproduction (aside from online dating) and how it actually came about is still a major area of research and debate.
Stranger
Off the top of my head, I know that the domestic turkey can reproduce via parthenogenesis. I think it is pretty rare in most birds but it can happen. Aves are probably the most complex species that demonstrate parthenogenesis, although not the largest.
Stranger
What about those fish that can change sexes? I know usually one of the females in the school will turn into a male when the first male dies or leaves or whatever, but has it ever been observed that a female will lay eggs, turn into a male, and then fertilize those same eggs? This question just popped into my mind.
Sorry, I don’t know what species of fish it is.
[QUOTE=Stranger On A Train On the other hand, there are some major difficulties with sexual reproduction (aside from online dating) and how it actually came about is still a major area of research and debate.
Stranger[/QUOTE]
One day someone will find one of the those ubiqitious “free 5 hundred hours” AOL disks and the mystery will have been solved.
forgive my dry, odd, and usually stupid sense of humor…couldnt help myself…
Carry on.
Blll
I meant “find in a geologic layer thats a few hundred million years old”.
Ughhh, the only thing worse than a bad joke is messing up a bad joke.
Blll
Nitpick: I’d phrase this as ‘species that are also sexually reproducing (or descended from such)’. I think parthenogenesis can be also used to refer to many species that ‘normally’ reproduce both sexually and asexually. For instance, aphids alternate sexual and parthenogenic reproduction: eggs hatch in the spring, individuals find a plant and then reproduce parthenogenically all summer; in the fall the last generation includes males which mate with females to create eggs that are laid to overwinter.
This is what I intended to convey. Species that reproduce by parthenogenesis typically reproduce sexually or are descended from species that did reproduce sexually but now reproduce primarily or exclusively by asexual (non-self-fertilizing) means.
Stranger
There are quite a few species of fish that are sequential hermaphrodites; that is, they start off life as one sex, then change to the other. But the transition is too slow for them to fertilize themselves. At any one time they are male or female, not both.
However, there are a small number of fish that are simultaneous hermaphrodites, that is, they are functionally male and female at the same time. Two fish pair up and engage in a series of spawning bouts. One will take the female role, and produce eggs the first time round, while the other acts as the male and sheds sperm. The next bout they will reverse roles.
Because eggs are larger and more energetically expensive to produce, it’s advantageous to play the male in these bouts. So some fish will attempt to “cheat” by not reciprocating with eggs after they’ve fertilized those of their partner.
There’s quite a few lizards and some salamanders as well. These are mainly triploid, the lineage originally having been produced by an interspecific cross. Because the triploidy screws up meiosis, asexual reproduction is the only option they have.
It seems to me “parthenogenesis” by definition assumes the species reproduces sexually (or ought to be capable of sexual reproduction); the term “virgin birth” is pretty much meaningless if the possibility of sex is nonexistent.