An evolution question

[Che Guava]

I don't think that the absolute number of species is currently going up, or has been going up, for the last 100 years. I believe our extinction rate is currently much greater than the speciation rate.
I'd be happy to be shown differently.

It certainly hasn't, but then again, biodiversity on earth has always gone through boom and bust cycles. I don't think that there is a natural trend towards greater speciation in an evolutionary timescale, just conditions that favour more or less species...

 

[Abaddon]

Im with Che here.. in times species number constricts considerably.. as resources deminish such as the ice ages.. but expand rapidly afterwards.

You need the niches available, for something to survive the evolution.

 

[Che Guava]

I'm sorry..I can't read your post..my eyes keep drifitng to you avatar...!

Very true: as long as there are niches availible, sopmething will come along to fill them. When the niches disappear, so do the species.

 

[Abaddon]

she is a bit good isnt she

Evolution at work!

 

[El_Machinae]

Well, I think our current extinction rate, while recoverable (on a geological timescale) is unpleasant.

 

[Abaddon]

Noone would deny this.. but TBH a lot more will get wiped once the iceage rolls in again.

 

[Neonanocyborgasm]

The evolutionist view holds that over time life on earth has become more complex and more numerous (more species).

No, it doesn't.

 

[Abaddon]

Some hold that view.. but an evolutionist is the belief we slowly mutated from a single point, rather than all created at the flick of a greater beings fingers

 

[warpus]

So I'm saying that isn't it strange that the speciation of a more complex lifeform has not been observed? Or is that to be expected?

What do you mean observed? As in, us watching it happen? Do you have any idea how long something like that would take?

 

[Abaddon]

it has been observed to see the change in average distribution- evidence of evolution.

There is no way you could see the speciation of a more complex organism.. it doesnt work like that.. animals slowly diverge from the origins.. only with fragmented Fossil data does it seem animals make great leaps in form suddenly.

You have to realise, between each two fossils denoting a change, there were a infinite number of animals between, slowly eaggerating the change.

 

[El_Machinae]

Noone would deny this.. but TBH a lot more will get wiped once the iceage rolls in again.

Over what timescale, though? Certainly not a couple centuries

 

[Abaddon]

True, ice ages roll by every 20,000 years i think.. tho we are about 50 years overdue already...

 

[Truronian]

Someone is really pushing for 7000

 

[Abaddon]

hey those facts are true.. i did A-level Geog

 

[Homie]

Humans have approximately 24,000 genes actually. Many plants have more genes than us - Wheat has an estimated 70,000 genes.

Both your numbers are wrong. 24 000 was the estimate before they had mapped the genome, ca 35 000 is the actual number they found now that they have finished mapping it. Wheat does not have 70 000 genes.

I saw Jonny's video link, it still seems unlikely to me.

 

[El_Machinae]

Both your numbers are wrong. 24 000 was the estimate before they had mapped the genome, ca 35 000 is the actual number they found now that they have finished mapping it. Wheat does not have 70 000 genes.

We don't really know the number of genes, actually. We can count the ORF (open reading frames), and then are able to find more variants of ORFs. But introns (and the like) confuse things; if an mRNA codes 2, or 3 different proteins ... how many genes is that?

 

[Brighteye]

The evolutionist view holds that over time life on earth has become more complex and more numerous (more species). In the last hundreds of years we have seen the extinction of many species. If life increases in complexity and number, we should have seen the rise of some species more advanced than their ancestors. So the question is: Has the speciation of a more complex lifeform than its ancestor ever been observed and documented?

And before anybody says:"Define complex!"
More complex means more genes, not the size of the genome, but the number of genes. The human is the most complex creature on earth with approximately 35 000 genes.

It's not a necessary part of evolution that the number of species increases. Nor is it necessary that complexity increases.
Some bacteria have 100,000 genes. Humans have about 35,000. We can mix and match parts though.

 

[Masquerouge]

No, it doesn't.

Agreed. A lot of living organisms today are as simple as they were hundred of millions of years ago - mainly because the vast majority of living organisms are still monocellular beings. Furthermore, the number of species has been shown to go through cycles of expansion followed by drastic extinctions several times.

 

[StarWorms]

Both your numbers are wrong. 24 000 was the estimate before they had mapped the genome, ca 35 000 is the actual number they found now that they have finished mapping it. Wheat does not have 70 000 genes.

I saw Jonny's video link, it still seems unlikely to me.

Wrong. 24,000 is the latest estimate who actually work on sequencing genomes. I am doing a degree in genetics and I have been told by several lecturers. The original estimate was 100,000. In 2001 the estimate dropped to 50,000. In 2003 the estimate dropped to 35,000. In 2004 that estimate dropped to 24,000. Now that MOST of the genome has been mapped, we know it to be around 24,000. It has not been completely mapped - areas like the centromere and telomeres contain lots of repetitive base sequences. The way people sequence genomes is to make copies and smash them up and look for overlapping bits. With repetitive base sequences it's very difficult to do. We can only assume that there are no genes in the centromere. Wheat has an estimated gene number of 70000 and is in the process of being sequenced. Wheat is an example of polyploidy which is why it has such a high number of genes. arabidopsis thaliana has been sequenced and is the model plant organism and has around 26,000 genes.

You have an out-dated estimate. http://www.genome.gov/12513430

if an mRNA codes 2, or 3 different proteins ... how many genes is that?

From what I've learnt so far, 1 mRNA codes for 1 protein (but that can be modified). However when there are introns and exons in an open reading frame you can get alternative splicing. Splicing cuts out the introns when transcription creates mRNA. However some exons can be cut out.

Exon 1 - Intron 1 - Exon 2 - Intron 2 - Exon 3

could produce mRNA of Exon 1 - Exon 3 or Exon 1 - Exon 2 - Exon 3

so one gene can code for more than one protein.

 

[Phlegmak]

Yes, in lizards.. drat source.. hmm.. basically on an island, a lizard was land based.. faster longer legged lizards could survive better

legs grow

new predator arrived

lizards who could climb trees away from predotor selected for

shorter legs could climb better

so evolution then flowed backwards. Now island populated with short legged, tree dwelling lizards

I posted that in another thread. Search through my posts and you'll find it eventually.