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Interview 9:04 - 18:21 Play 9:04 - More
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Tony Coates, Jeremy Jackson  

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Geology; Paleoecology  

Interview 23:54 - 1:03:18 Play 23:54 - More
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Tony Coates, Jeremy Jackson  

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Geology; Paleoecology  

NPR/NGS Radio Expeditions
26 Mar 1995

    Geography
  • Panama
    Darién
    Locality
  • Rio Yape
    Latitude/Longitude
  • 8.06841   -77.31982
    Habitats
  • River
    Channels
  • Stereo
    Sampling Rate
  • 48kHz
    Bit Depth
  • 16-bit
    Recorders
  • SONY TCD-D7
    Microphones
  • Sennheiser MKH 30
  • Sennheiser MKH 40
    Accessories
    Equipment Note
  • Stereo=1; Decoded MS stereo; Sennheiser MKH40 Cardioid Mid Mic and MKH30 Bidirectional Side Mic

PANAMA
DARIEN Logs Dat # 5
NOTE FOR AMBIENCE:
NG = no good, do not use
G = ok
VG = very good
E = excellent

NOTE FOR CONTENT:
* pretty good
** great
*** outstanding
**** must

stopped at another outcrop -l¿eo approaching the guys see if anything worth discussing
walking.... setting up the chatter about where to set up
not going to be much different here..we could walk down there and we could record the bird sounds ...
00:58 on the boat...do we want to drift? AC: yes, let's drift lets get closer to that net.
1:18 -FX: birds chirping water lapping, CJ: just when we hit that corner
there sound of the motor revving up muted yelling in Spanish, birds chirping....
1:44 boat begins to go -revving of the engine, birds chirp louder, yelling in Spanish, setting up of the boat
1:50 man yelling in Spanish, rapids running. windy no good..... i didn't recognize the governor.....wind...rapids but wind in the background ruin the sound...wind, the muted sounds ...
3:15 leo: we can turn off the motor ...
wind ruins all of this scraping noise...
lapping of the water -an oar going through the water.... spanish/embera in the background muted ... speaking in Spanish/emberra...wind? waterfall.... intermitten laps of the water from an oar. chatting about the fishermen and the setting up of the nets.....
bueno... speaking in spanish.... lapping of the water, the wind again, water fall sound, .. is it the rapids?
they aren't going to pull the net for an hour
7:56 on land now walking to the outcrop....chipping and water noise, some wind
8:27 the scientists are walking... leo breath in the sound
8:48 FX G chiseling and banging away at the rocks, looking for fossils (?) sound of rocks falling into the gravel...gravel swishing around
9:05 ac: jj in the context of this place what does bingo mean?
jj: yeah, well i thought i'd really found something. i'd found -i' d found see that large tured gastropod (?) which is broken in two pieces there's that and there's that and i thought ah, i found a place where they are going to be fresh enough there's a place
9:22 ac: these are, what i am looking at is this (loud -awful -scraping noise) can is um small seashells (9:30 chiseling in the background -¬looking for fossils) that look like the tail end of conchs 9:35 jj: yeah, snails and clams that... 9:37 chiseling continues ...there was a very rich fauna here clearly but it's all weathered the shells are very fragile (hammering in the background) ... FX tumbling of some gravel...if we um dig down into it we might find material that's good enough to collect one large bag of that could be washed and processed in the lab, but for larger snails and clams (hammering) the way you collect them well is that when you find them just sitting in the matrix of the outcrop and you pick them up one by one...water running, a bird chirping...and um there was a place somewhere along this river where we found a fair number of snails of a group we are interested in... (10:16 jj's voice get's muted a bit...other peoples voices heard in the background... ) but this is really (10:20 FX chiseling of the rocks) really not impressive at all (hammering, gravel noise) if this was a good outcrop (reaching for something, ...gracia electro) outcrop this can would be full in the first minute and i would go back and i would get a dozen cans and we would fan out over it and we'd fill them in half an hour....so i think there will be a sight which is substantially better than this but none of them will be like the gatune formation were go and you'll see that in a couple of hours we'll pick up a bushel basket full of fossils ... of large large ah... so, another disappointment basically (these last words are muted)
11:25 ac: you spend 20 minutes looking at an area that uh, maybe half the size of a football field and that's enough for you to know what's there you make
jj: we can make a very quick judgement as to the quality of the place (ambi: shoveling, digging, walking on gravel) if this outcrop were rich it could take us the entire day to collect from it because we'd first fan out and glean all the obvious shells and then after that we'd look for horizons that were particularly rich and excavate them and then after that we would collect large bulk samples of the entire material to wash through sieves in a laboratory and eh this is a large outcrop it a it's just not one in which the material is well preserved
12:13 tc: one feature you can see already though is almost everything we've picked up is different ac: huh tc: to i mean to jj's eye for example or to peter young who works, who is the specialists on the mollusks(?) i couldn't quite judge that but maybe there's only a couple of specimens that are the same (12:31 two people speaking Spanish in the background)so, considering how few specimens we've picked up we already have a surprisingly large species list... [12:40 -jj interrupts: there about ten genera of mollusks in that can] and that's very typical of the tropics that gives you some idea of that if you extrapolate that on to several bags (background:young voice in spanish)and several kilos um you might get a huge list of different kinds of species.
* 12:55 jj: the fauna of the darien is probably something on of the order of a **thousand different genera of mollusks** {emphasis on the rich variety of species that once lived here} (ambi: deep breathing in the background) so and at a good outcrop we can easily find a hundred definitely.
ac: huh
)): [ambi: background people mumbling]so there -but if -after we eat lunch we excavate and with and get down so say oh ten inches or so, maybe a couple of feet into the outcrop we'll find fresh material and although the density of shells won't be all that high it'll be worth while bagging that and taking it back to the lab and washing it up because that fresh material the shells will be in much better condition and they'll survive that processing and then that will give us especially since all of these things are small that will give us a moderately decent (13:53 loud coughing in background) estimate of the smaller mollusk and fauna that was present here.
ac: alright
jj: then we can look at those and we know from the mineralogy of the -the composition of the shells is well known for lots of mollusks (14:04 birds singing in the background) and there (14:09 humming of a child? in the background) are two common forms of calcium carbonate that make up the shells -gracias
[14:16 ambi: shells and small rocks being dropped into the tin can] that make up the shells of mollusks calcite and aragonite and calcite is more resistant to solution than aragonite. if we discovered that the great majority of the mollusks that were represented in our collections were calcite that would be further proof that we are looking at a very small remanent fraction of the original fauna with the aragoniticans the ones more easily dissolved having disappeared and looking at that simple ratio of the relative abundance of forms that have the two different kinds of mineralogy in their shells is one of the many kinds of evidence that can be used to assess how decent a sample you have eh and that goes with all groups that make calcium carbonate skeletons so, um...
15:08 tc: that's one of the problems of paleontology. if you don't do that and somebody for rocks that they think are the same age as here collect them and there the preservation does have aragonite, they come up with a list and a fauna which they describe and then they look at another fauna in another region and say that this is twice as abundant and these species don't occur here but they do occur there they are not looking at the original biogeography of the species they're looking at the artifact of preservation the filter through which a geologist
15:42 jj: and sometimes that can be pretty funny, I mean, imagine a time sequence in which you have preserved very well both forms and then at the youngest point in the section you're in a situation where the aragonitic forms aren't preserved. someone who wasn't suspecting could say aha, there was a major extinction event at this time, and it wasn't extinction at all . it's what's called taphonomy. the science really of the artifacts of preservation -the process of preservation of the fossil record. what you would say that's not an extinction that's just a taxonomic artifact; a bias of preservation --you can see that Lacho knows what he is doing; he's a very good collector.
16:26 tc: he's just handed us a nice handful of mollusks. it's the other reason you want to replicate samples because if we don't get the aragonite ones here we'll get them somewhere else and by combining all of those collections you finally arrive at a representative sample of the fauna.
jj: there's most of a snail, you see. and in fact Young/Jung? [16:50 ambi: wind starting up again] can do a lot with that, because the nature of that apex is diagnostic taxonomically, so he can put that in a genus instantly just from that fragment
17:59-17:03 FX: nice river sounds --but not very stronq --birds sinqinq, with the scrapinq of tools lookinq for fossils, but the sound is ruined by the wind
* 17:03 tc: you can have mollusks that so rich, that the rock is just mollusks he rock itself is all animal -100\ animals...when you reach that, when you qet those opportunities you qet lists of species that are in the hundreds.
17:21 jj: this little piece of matrix is much tighter [Leo whispers "alex"] than most of what we've been seeing and the shell is you can see from a distance is in much better shape so even just within the distance of a meter along this outcrop service is a great difference in the quality of preservation. this is actually well preserved, most of those things aren't, but this is a very hard matrix around.
**17:46 tc: here's quite a nice [ambi: clink of a fossil in the tin, water runninq] so you can see with the frequency that we are finding them if this was a unique time horizon it would be worth us coming with seven or eight people and just sitting it looks and is to some extent boring but you would accumulate quite a large collection by just persisting collecting and perhaps with a large number of people [background: water running, feet walking... ] where as one person in ten minutes could collect, um, the same volume at a very rich outlook(?}.
18:20 -18:58 ambi: this would be potentially good sound of people digging and the water running, with the birds singing, but the sound of the wind is too prominent... THIS DOESN'T WORK.
18:58 jj: (?) and so you see it's good the timing of this because after seeing us be frustrated through all of this time we will go to this one place in the end and and it will be nirvana. laughter...
ambi: digging, water running....too windy...
19:20 leo: the wind has picked up a little bit... jj: yeah, i wonder if it's going to rain... leo: it could...
pause....
*19:33 tc: actually when you take some of these blocks out you can see that there are dozens of small mollusks in them ...ambi: chiseling...see every one of those little white flecks is a mollusk...
G 19:48 FX: chiseling... through 19:58
19:59 tc: now there's a rare?? that's covered with them jj: (to a Panamanian) gracias..
G FX 20:05-08 chiselling, the sound of a bird cooing...strong wind sounds...water rapids ... the sound is a bit strong, but good powerful hammering sounds FX: good sound, (but the wind!!!!) hammering away at the stones, looking for fossils, sound of the little pieces of rock falling to the ground, a grunt from tc...
20:13 tc: maybe worth bulking, no? jj: yeah, i think so tc: there's another one
20:20 G FX hammering...chiseling...through 20:31, then the wind starts up
*20:36 G tc: that's nice...
20:42-20:59 G FX....hammering--at a faster pace, chiseling...
21:06 tc: now there's a good pectin(?}
21:10 G FX ...banging at the stones...clinkering of the tin...banging...... jj: (to the panamanian helping him) por favor...gracias ... bangingthrough 22:16 ... jj: pretty boring.... it's cerads, coevals ... FX -blowing off dust? to see what he found?
22:27 jj: it's a little fresher down there
22:29 tc: yeah, there's a huge number of micro-mollusks in here
22:34 -22:40 OK FX-hammering...
22:44 jj: huh. it's starting to get fresh tc: yeah, darker and nice...there you go. jj: what d'you got? NG ....
22:50 tc: ...there you go because it's darker and the stuff is better preserved
22:56 jj: there was a place over there where i found three "ratty cones" wonder if i dig there more tc: there you go, yeah tc: now here the preservation is pretty good. here, look at that....mummbling btwn jj & tc
* G FX 23:18-20 hammering...
23:21 tc: no, you are right. the shells themselves are pretty punky...well, do you want to go and look at the other and see if we can get something out of the other jj: yeah
NG FX 23:28 -23:48
23:49 ac: how many hammers does a geologist go through....cut off
23:53 NEW SCENE....
ac INTERVIEW with jj & tc:
about the isthmus and biodiversity... interview.
24:20 )): .. which sort of relates to this other question about isn't darwin settled ac: yes jj:and whatever,because that's really the whole business of punctuated evolution or gradual evolution but it's just a different thing... i am not trying to be thick...
tc: and the isthmus of course is one place where you can actually test
jj: yeah.. it's the classic
24:55 ac: we are in the emberra capital village on the -what is the name of the river?-tc: tweida ? river ac: tweida river in the darien, tony ¬
25:05 tc: i am tony coates and i am the deputy [banging of a tin can? in the background] director of the smithsonian tropical research institute and a geologist scientist who also works on [talking in the background] this project, the panama paleontology project, with my colleague who is opposite me
25:23 jj: my name is jeremy jackson i am an ecologist and evolutionary biologist and paleontologist. i work on coral reefs and eh, the evolution of mollusks and bryozoans ?
25:38 ac: just explain evolutionary ecology if you could.. i don't know if it's the sort of thing you can explain very briefly
jj: well, ecology is the study of the distribution and abundance of organisms and the processes that effect their distribution in abundance. paleoecology ecology is the study of past patterns of distribution and abundance and attempt to understand what caused them. so it's really the same science it's just a historical aspect of the same problem.
tc: one of the nice features of it though is if you are interested in modern day problems you have the effect of humans on a very massive scale, and one of the things that paleoecology can help you with is to see what processes went on and what changes occurred before humans arrived.
26:30 ac: um, here we are, a considerable distance up a river from another river, eh, and um, and you're looking for -you are a coral reef man and a mollusk man, and you are a geologist, why be here. let's ask the geologist. why is this a place to look for that kind of material.
26:51 tc: well, when we embarked on this project, um, we wanted to utilize the fact that
26:58 ** the isthmus of Panama had risen up over a series of millions of years and separated a previously single ocean into two very different oceans or two oceans that became because of that uplift, very different. and after a series of surveys in different parts of central america from ah, Ecuador in the south up to Nicaragua in the north we focused on two regions where the evidence for the past changes were most extensively developed. and one of those was on the northwest coast of Panama, bocas del toro, and the other was in the darien which is where we now are. so the reason we've come up here is to try to get evidence for the last 7 or 8 million years of the history of the isthmus with sediments that ended up on the pacific side of the risen isthmus.
27:57 ac: what is it about your partnership that makes you want to work with each other? that is, you are not scientists in the same field.
* 28:05 jj: well i'm fundamentally a biologist, and although i come out here and i work with rocks and fossils and things that have been dead for millions of years, i think like a biologist i am interested in why organisms occur where they do what are they processes that have lead them to be where [some hammering in the background] they are and things like that. tony is fundamentally a geologist. he is a physical scientist. although he has experience working with fossil groups and the like he perceives the problem as one of the creation of the isthmus. how that came to be, and not so much the consequences of it biologically, and so we compliment each other in the sense that one of us brings to bear on the problem the physical scientific perspective and the other the biological perspective.
28:52 tc: if you want to understand why that's necessary if Jeremy wants to ask biological questions he has to know whether the same animals on either side of the isthmus are of the same age or not and he needs to know that for each of the ages back into the past that we are going to study so my job is to go out and recognize the different strata, identify their ages, arrange them in a chronological sequence, and compare them on either side of the isthmus that produces a temporal and a spatial framework and there are a variety ways that this established starting with coming up the rivers and measuring the rocks and orienting them in space and then following up with a series of steps using fossils and paleomagnetism to date them. once that frame work is established, i sort of hand it over to Jeremy and he takes the organisms and looks at the patterns that that permits
29:50 jj: it would be very nice if i could just take that for granted but in fact one can't and the only way one can do interesting paleoecology or evolutionary studies is to be sure that you can have confidence in that frame work and it's a very unusual circumstance to be able to collect such a vast amount of paleontological data in a really well controlled circumstance which is what this project has given me.
ac: you've talked several times about replicating material which i think is what you mean by a vast amount of data. replicating your data along many rivers different levels of these different sites from these different rivers. what is it about replicated this material. why can't you just go once and get the stuff -figure out¬
30:47 tc: i suspect there'll be a slightly different answer from each of us. my answer is that not only does the biologist-do the biologists who are working on this project want to know exactly what time each of their faunas that they collect represent. they also want to know that they are comparing animals from the same sets of environments that existed in the past you are going to get a very different picture if you compare a coral reef with a river estuary. so, since the only places that we can see fresh rocks that contain beautifully preserved fossils are in the rivers that run across the land and cut, as it were, wounds through the sequence so that you can look in and see fresh stuff your anyone river is only going to go through a limited set of environments back in the past. and so, we want to go up several rivers over a considerable geographic area such that each of the rivers gives us a new chance to sample a different set of environments in the same way as a coast line would change in different habitats if you walked 600 miles along it, so will sampling over 4 or 5 hundred miles or even 1 or 2 hundred miles different rivers will give you different examples of environments that existed at the same time. with that you can put together a much more complete picture of how the world was at 5 million or 10 million years
32:22 ac: the distance that we have traveled up this river, say today, we went 5k up the river and you looked at strata up there and then we came back down to this area, 5k, presumably the strata from farther up that's a younger strata then what you are looking at down here. is that correct?
32:50 tc: not necessarily. strata don't just lie there in a single orientation and behave consistently throughout the river. so at -that you may have noticed as i was measuring dips you look in my field notebook, those dips differ quite considerably
ac: a dip is a ¬tc: a dip is the geological convention of inclination of the plane of the stratum such that you identify the maximum slope -the maximum inclination -hence the word dip, and those are singled on a map with....an arrow and if i am to work out a chronologically sequence using the inference that the youngest beds are going to be on top of older beds i need to know whether i am walking up a straight pile of uniformity dipping rocks or whether i'm sometimes going up, sometimes going down, which would imply that the rocks are first dipping say to the north and then are starting to dip to the south and then back to the north again. my calculation for the thickness and number of beds that represent different times will be quite different then if they are folded and if they are not. so i need to disentangle the structual convulsion that have taken place to the settlements since they were deposited in order to get the correct calculation of what are the different slices of time present.
jj: if you imagine a cake of three layer or five layer cake and each layer of the cake is a different color, if you slice the cake with a knife from the top to the bottom you go through a short distance to get to all the five colors if you slice the cake absolutely parallel to the top of the cake you'll go through only one color the entire time and if you do it on a diagonal it will take you longer to get through the five colors, but you will get there. the problem of dip and inclination is basically the problem of how to cut a cake. so, if you want to go through a lot of time quickly, which is the ideal for us, to be able to go with relatively effort through a lot of time and history you hope for that slice to go through from top to bottom. and it rarely does, and the question is how much the diagonal is today we might have never gotten out of a single layer. we may have gone for ten k or what have you, moving up and down slightly just within say the middle layer of the cake which means we took many samples from slightly different versions of the same environment and eh there's nothing we can do about that. but he's the person that has to figure that out. he figures out how we cut the cake of time, and environments and by figuring that out he provides me the framework of what i need to do. umm....to go through the five layers of time would be a great sample, to go through just one layer would be to better sample a single time.
36:00 ac: why is the isthmus a good place for the kind of project that you are undertaking?
* 36:06 tc: well, the isthmus is one of the very few places in the world where you have had a barrier appear at a known or approximately known time in the past between a formally whole ocean, relatively uniform ocean, in --a tropical ocean in this case, and divided into two, and when it was divided into two, slowly, over several millions of years forces were set loose which triggered fundamental changes at the surface of the earth, possibly the most fundamental in the last 60 million years since the famous collapse of the dinosaurs and the...to give you an example some of the changes that were probably triggered [FX: the sound of water running, with great force] were the fact that the water which previously flowed from the Caribbean through into the pacific was stopped, turned around, and sent northwards, past Florida, across the Atlantic, and bathed northwest in Europe and in Russia with warm moist water.
37:12 that's one of the reasons why London and even Murmansk, way up in the northern latitudes do not freeze during the winter where as Halifax and St. Lawrence sea way freeze every winter that effect not only keeps all the European and Scandinavian ports open it also probably provided the moisture that triggered the glaciation in the northern hemisphere that started about 2 million years ago. the same effects continue through for example causing the Caribbean to become warmer, to become more saline and, as we've seen, provide a tremendous environment for the flourishing of reefs. on the pacific side the water was stopped from coming through the winds continue to blow across the isthmus pushing the surface water westward and so cold water wells up from below. the pacific then is much colder much more seasonal, because that only occurs in one season in the year. It, it, that brings nutrients up. the nutrients feed a long food chain which causes a tremendously rich seafood productivity in that ocean...and probably also triggers off such things as el-nino the famous episodic global climatic and oceanography change in the pacific so, that one little sliver of land coming up triggered an extraordinary range of global changes.
ac: but it triggered evolutionary changes as well
38:51 jj: and the interesting thing about it --those changes were really rather small in the water. the evolutionary changes that were triggered by the formation of the isthmus which are very well know, and extraordinary dramatic was the countenance of land by 111 the northern and southern hemispheres. and that resulted in a massive invasion, of animals from the north into the south with consequent extinction of southern forms and a great radiation of the northern forms. in south america that's long been studied and its remarkable and dramatic event of the history of life on earth. in the oceans for all of these differences that tony was describing the changes that occurred in thee evolution of species are really remarkably subtle. it's true that coral reefs disappeared from the eastern pacific and it's true that a few groups diverged rather dramatically on either side but in spite of the fact that we know that this is a complete geographic barrier, and that we know when it was finally formed and completed, the amount of evolutionary change that has occurred in the creation of new species on opposite sides of the isthmus has been really remarkably small. it's been so small that if i were to show you species of sea urchins and shrimps from opposite sides of the isthmus and didn't tell you where they came from, you wouldn't be able to tell them apart in most cases. the differences are so subtle that they require a taxonomic specialist to study. so we were completely fooled and surprised by that we thought that what we would find biologically would be an affirmation of this great geographic experiment. isolation by geography. and instead what we found is that some of the processes that tony was first talking about were the most interesting and important. that the triggering of the ice ages in the northern hemishpere were some how responsible for a remarkably quick and profound change in the biota of the oceans on both sides of the isthmus for reasons presumably related to cooling even the tropics. although exactly what happened is quite controversial. and in this brief period of time perhaps as short as a few hundred thousand years approximately half of the species of corals and mollusks and bryozoans that were alive before it became extinct and new species formed. and we don't begin to understand the basis for that kind of profound and rapid turn over in biota 11 but it's clearly not due to geographic isolation. and the implication of all that is that the way we've thought about species being formed in the ocean might really be quite wrong. that most of evolution occurs perhaps in these relatively sudden pulses independent of processes of geographic isolation that we've always focused on in the past.
42:16 ac: you've mentioned the shrimp... i think nancy showed us slides of these shrimp and said these can no longer hybridize...there have been...
jj: oh, there have been perfectly good new species formed. whether they can hybridize or not, biologists quibble about [FX: sawing in the background, wind blowing through grasses?bamboo? .. ] what how they define species and whether or not they use absolute reproductive isolation as their criterion for speciation. but there is no question but that the organisms have evolved to be different from each other. it's just that the amount of differentiation but there's no question but that the organisms have evolved to be different from each other. it's just that the amount of differentiation that has taken place is surprisingly small. to put it another way, the isthmus finally closed approximately three million years ago. 43:06 three million years is 5% of the time that's taken place since the extinction of the dinosaurs it's longer than the amount of time taken for the evolution of the advance forms of the genus homo and the entire radiation leading up to the origin of our own species. those evolutionary changes in human evolution ah are vastly greater in that short period of time than what happened in these organisms. um... and in fact we know that within only a few million years after the beginning of the modern era, the tertiary era, after the extinction of the dinosaurs, that major groups of mammals on the land, and that major groups of invertebrates in the sea were formed, eh, in only a few million years. so groups that are as different from each other as different kinds of snails that you would take one look at them and say -oh, those are very, very different, originated in the same amount of time that these trivial differences resulted in the forms that were isolated in opposite sides of the isthmus. 44:24 so, its really taught us -we think -an extremely important lesson which was utterly unexpected. that geographic isolation yes, indeed it does result in the formation of new species; but in fact the amount of change that occurs just from geographic isolation alone is really very, very small. 44:47 and that is forcing us to look at other factors in the origin of the diversity of organisms we see today.
NOTE: throughout this above piece there is distracting background sound....baby crying, faint din of people talking.....also.... i don't see how we could use this info... it de-emphasizes the main reason why we are there! ! ! !
44:57 ac: eh...... 45:03 how do the changes that are brought about by the rise of the isthmus [45:04 FX: water running? a sudden rain storm?] inform your view of biodiversity today. is that you are saying that the half of the marine organisms died out as a result of the ice age ....which is, eh...
45:26 tc: well, there are other effects that jeremy hasn't mentioned. for example, um, there are significant changes in the biotas -or the species of animals that live in the sea -before the three million years at which the isthmus closed, and we know that the effect of the beginning of the rise of the isthmus effected different organisms in different ways at different times. for example, some time around em, the end of the middle Miocene, perhaps around ten million years or so, eh all of the oceanic plankton that make their skeletons of glass, of silica, disappeared from the Caribbean whereas they flourish and continue to evolve in great abundance today. many of the people studying the planktic and benthic foraminifer they we've been discussing -dating and so forth -notice very significant turnovers and changes in speciation in those groups before the actual closure of the isthmus, and i think jeremey -in the small bionics ? too -in some of the snails -isn't that also the case?
jj: there's no doubt that environments changed for a variety of reasons clearly due to the formation of the isthmus to some degree and for other factors. and some groups diverged dramatically in these different circumstances. and in a few cases it can be argued very strongly that the primary cause for this divergence was the formation of different environmental conditions on opposite sides of the isthmus. urn, what i was trying to say before was that on average taking just the issue of isolation per say and the formation of a barrier per say, which is something that evolutionary biologists interested in speciation have focused on in a very extreme way. the results of isolation per say seem to be trivial in comparison to other evolutionary changes. we have a very poor understanding of the sequence of environmental changes that have occurred on opposite sides of the isthmus. we're just starting to put together the skeleton of what we think may have been the major factors involved in the development of the different environmental conditions of the type that tony described for today. and it may very well be that i am being a little too pessimistic or a little too hesitant to ascribe effects. but what i see as a biologist is an extraordinary and dramatic event approximately two million years ago due to a global climate change in some way or another which so dramatically overshadows the consequences of these regional differences on the opposite side that it's really -it was quite, quite unexpected. being able to study that event however in the context of the isthmus because the nature of the evolutionary response in the pacific and the Caribbean was profoundly different. and it maybe that after we have a better idea of the conditions that led up to -urn, the way environments change on either sides of the isthmus through time, that will allow us to understand why the fauna has turned over in a different way 2 million years ago.
49:02 tc: perhaps for a lay person what ought to be made clear is what jeremy is describing is clearly an increase in biodiversity in that if nancy is right and if harris leslius and some of the other marine biologists at STRI that you've talked to we do have species formed, than clearly the isthmus has increased the biodiversity in marine world
jj: by roughly a factor of 2
tc: two -but it hasn't been anything like the origination and radiation of all of the mammals all of the genera of mammals after the demise of the dinosaurs which took place in a sort of a similar time frame so the -the ¬you've got to talk about a difference between just numbers of different species being generated versus the extraordinary morphological or different kinds of animals that came into being for example in the end of the Mesozoic with the demise of the dinosaurs ¬
jj: if you think of evolution as a creative process and the formation of whole new ways of living the change of the biota that occurred in this short pulse event was a very creative process. it resulted in the development of aquapored corals for example -the staghorn and elkhorn corals of the Caribbean that dominate coral reefs in the Caribbean and equivalent forms in the pacific. they are the essence of reefness today. those forms came into their own 2 million years ago in this turnover. the modern biota of the oceans was created in this turnover. it was a very creative event. the kind of evolution that's occurred on opposite sides of the isthmus to our great, great surprise has turned out to be the most subtle kind of fine tuning of the same body plans that already existed before and that really was a surprise, and it really made us question whether or not the paradigms of evolution as we've always thought of speciation operating in the sea were correct and i think many of us are beginning to believe that they are not correct and that geographic isolation yes, does lead to different kinds of species but if you have to be such a specialist to tell them apart then clearly, that's not where the action is in terms of the creative process of evolution in the oceans. that may be very different from the land, we have no idea but we have something most of the terrestrial biologists don't have -we have a really good fossil record, so we can make these kinds of statements with a real degree of confidence which simply isn't possible for most organisms that live on the land.
52:02 ac: although, why is it better to make this statement? why is it easier for a marine biologist to make these -draw these conclusions rather than ah ...
52:11 jj: because a clam or snail that lives in the mud or the sand is already in the environment when it dies, where it has some kind of a chance of being preserved, and the environments -the marine environments are much more vastly extensive in space than terrestrial environments, and they are already down low in a position where they have a chance of something more being deposited on top of them. terrestrial environments are by definition ephemeral. they are being eroded. all terrestrial environments are being eroded for all practical purposes. even lakes that are depositional environments that are raised above sea level are subject to erosion very soon. and so the chances of preserving terrestrial environments are relatively much smaller. and also the chances of say a rat or a mouse being carried down the stream and buried in mud, and some how therefore possibly preserved are far less than for an organism that's already in its grave as it were.
53:15 tc: but even in spite of that, if you take this same isthmus and look at the fossil record of the connection and here we could perhaps make the contrast between what jeremy is saying about the subtly of the division of marine organisms by separation, even with their much weaker fossil record. the connection of two continental faunas that were previously separated triggered phenomenal changes in the diversity of the organisms. i mean south america was a continent with no deer. when the deer crossed the isthmus they radiated to such a degree that there are more species in south america than anywhere else in the world. and whole categories of organisms went extinct and were replaced by others, and so forth. so, the connection of two previously separated groups of organisms seems to have triggered very much more dramatic changes than the separation of previously similar organisms.
54:12 jj: and that may in fact be general. there is a fellow named gary vermay who works -who is a biogeographer and has worked here and has also worked on the Bering strait and tried to ask similar kinds of questions to the ones we are asking about the effects of the isthmus for the Bering strait, and the separation of arctic ocean and north pacific faunas. and i think he would agree that it appears that connecting things has far more consequences than separating them.
54:47 ac: what if... i don't know that your project will... is the kind of project that one ever completes. i mean this is the gathering of data and presumably you keep going on --but what kinds of questions about biodiversity will you answer -in 10 years -in 15 years?
55:05 tc: well that's a much better question for jeremy to answer. i could only say to begin with... that if you first of all want a record of biodiversity, and you want it back through time you have to go through this extremely laborious process of um, looking at rocks in as many different places, correlating them in time as we have just discussed and then painstakingly collect as much of the fauna bulk sample it in large quantities of sediment wash it up, take it out, break it up into it's different biological groups and send it to the specialists that describe them. and if you want to know what changes are occurring today in biodiversity through anthropogenic as well as climatic and other changes you presumably want to set that against what the world was like before humans came into it, and that involves a protogists amount of work in taking each time slice and laboriously looking at the various environments within it and collecting the faunas from each of those environments and describing them and characterizing their diversity. then you can see whether the world is getting more diverse or getting less diverse; whether some dramatic changes have occurred constantly, or whether they occur in punctuation, and that's very much more jeremy's field and i think he should comment on it...
56:26 jj: the, i mean, there are many people who run around today saying that we don't even know the diversity of organisms living on the earth now, much less than the past, and that's true, and people argue about what is the diversity of animal life on earth by a factor of 20 or a factor of 50, and we can't contribute much to that -but what we can do is we can take groups of organisms that live in shallow oceans of the tropics and we can ask using them as a model system. how do they change through time, and if they change through time in their diversity in the kinds of organisms that are more or less abundant, or what have you, why did they change. with...there is a great deal of interest in global warming or any other factor that you can think of that people talk about and they worry about. well the earth has been warming in the past, and its been cooler in the past. the world has had more carbon dioxide in its environment in the past, and its had less in the past, and um, obviously, organisms are still there. that doesn't mean that changes that maybe going on now might not have very considerable consequences, but maybe they will, maybe they won't. what we can do is we can look at the diversity of life in the same general categories of environment over a very long period of time. during which time some profound environmental changes occurred. and we can, we hope, better and better and better document those changes. and then we can ask what kinds of environmental changes appeared to had dramatic consequences and which ones have not had dramatic consequences. and did they happen fast, or did they happen slowly? and in that way, if we learn nothing else from that, we will get a sense of how buffered systems are, and how quickly they can change and in what ways they change. and that's an insight or a perspective which simply isn't going to come from modern biology. and i can give, i think, a good example of that. the first -for some reason ¬roughly 2 million years ago, when there was a great turnover of the fauna and the sea, and also by the way, on the land, we can make up a story and we can say, well, almost certainly this is somehow related to the intensification of glaciation in the northern hemisphere. we don't know whether or not it was temperature, or the confounding of temperature with other factors, but something related to the fact that all of a sudden glaciation was intense was associated with this great extinction and radiation of new species. well since that time there have been roughly twenty glacial episodes when the temperature got cooler and then got warmer, and cooler and warmer, and nothing happened. there's been almost no extinction and almost no origin of species in the tropical marine environments we study for 2 million years. so you can say, well, then clearly its not the changes in conditions that are due to glaciation to which i would say, no that's not true, because what we have left are the organisms that survived that first initial shock related to glaciation and as survivors by definition they can cope with the same events over, and over, and over again. so it's not just the nature of the event that takes place. it's also the timing of the event; the originality of the event. it's as if a group of organisms that make up a community have an evolutionary portfolio. they have experienced in their history, in their genealogies, a sequence of events. and that sequence of events determines whether or not -how they will respond to a new event. having respond to it, those that have made it through that latest hurdle are going to be able to respond to a similar event over, and over, and over again. and one can't begin to have that perspective unless one has the historical record of showing when the species appeared, when other forms went extinct, and what was going on at the time these changes occurred.
1:01:04 ac: let me ask you about the isthmus and speciation. are you saying that darwin is wrong is some part of his general theory of evolution?
1:01:17 jj: well, no. darwin had a concept of evolution requiring an enormous amount of time. darwin was deeply troubled by arguments among physics and geologists about the age of the earth. because if the earth wasn't as old as he wanted it to be, then there couldn't be possibly be enough time for evolution to occur. and that was because he had this concept of evolution being an imperceptibly slow gradual process. in fact, the evolution that occurs on opposite sides of the isthmus is good Darwinian evolution. it is extraordinary slow evolution over many millions of years. what darwin might have found troublesome are these turnover events --these pulses of evolution in which many different kinds of organisms go extinct or evolve at geologically the same instant. that's something he wouldn't have been prepared to deal with. and this is very much like the controversy of punctuated equilibria and evolution that's associated with the names of Niles Eldridge and steve Gould. and when they first proposed their idea of punctuated speciation, there was a lot of running around saying, oh this is non-darwinian. but really it was entirely Darwinian. it was more a question of rates of evolution than it was of the nature of evolution. and after an initial defensiveness the giants of modern evolutionary biology have managed to package punctuated equilibria into their beliefs system with great efficiency.
1:03:06 tc: it still changed through time by selection it's just is in series of major gulps instead of continually...
1:03:41 jj: i can tell i through you a ringer ...you didn't expect me to say that at all (laughter)
ac: pack it up! we're going home!
1:03:52 END

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