STEPS TO A REMARKABLE EVOLUTIONARY DISCOVERY

Discovery of the extreme age of the likely longest-lived animals on this planet was a slow process over many years.  It involved the combination of many discoveries by others that has not yet been comprehended by my peers, many of whom are much smarter than I am.  That the animals, the Pogonophora, are also closest living relatives of the link where the change from one major branch of the animal kingdom, the protostomes, gave rise to the other major branch of the animal kingdom, the deuterostomes, becomes understandable and obvious when all the facts are considered.

Getting ready for the discovery.

My early dreams as a biologist were to focus on some obscure invertebrate, that no one was interested in, so I could be the world's expert on an organism.  I didn't intentionally pursue that goal in graduate school, although I realized that many important discoveries had been made by people who were not looking for their discovery.

My master's degree research was about colony growth rates of a protozoan and its lipid cytochemistry as related to culture pH.  For that, Dr. Richard Fennel was my advisor at Michigan State University.

I began doctoral research at The University of Tasmania with the aid of a U.S.  Fulbright Scholarship to Australia in 1956.  A planned study of river pollution as indicated by invertebrates of the Derwent River was abandoned as impractical.  The chair of the zoology department there, Dr. Vernon V. Hickman, suggested a poorly known isopod crustacean living in pools on top of Mount Wellington as a good object of study.  It was.  Dr, Eric Guiler became my mentor for the isopod study while I was at the University of Tasmania.

Dr. T.  W. Porter became the chair of my doctoral committe at Michigan State University.  On my return, the committee thought I should enlarge on the comparative studies of the Tasmanian isopod with a somewhat ecologically equivalent Michigan isopod.  Both lived in temporary ponds approximately the same distance from the equator.

The isopod study provided background for understanding principles related to adaptive changes, early embryological development and extremes of life cycle length associated with anatomy, physiology, and environment.  I had no premonition that I would find it was preparation for recognizing important elements of the life cycle extremes, anatomical, and embryological adaptations of an organism with such evolutionary importance as the Pogonophora.  At the time I, like most biologists, had not even heard of the Pogonophora.

 Developing an interest in Pogonophora.


The interest came gradually as I taught invertebrate zoology and found out about the new minor group of worms, the Pogonophora, having no mouth and no agreement on how they took in nutrients.  The experts asserted that they were minor, degenerate, dead end, tube-dwellers of no evolutionary importance.  I found them interesting for having so many rings on their tubes, a possible indication of greater than usual age.  Most species were found at great depth, embedded in the ocean bottom.

Western Michigan University was the host of the C. C. Adam's collection of books and journal papers collected by the early ecologist.  The C. C. Adams Center published a series of ecology papers and used the publication in exchange for other publications.  One was Sarsia, a Scandinavian publication I might never have otherwise encountered.  M. Webb had several research reports in the 1960's; in 1964, two of special significance were published.  The first, described a rarely recovered rear portion of the worm with annelid like segmentation and setae.  The second, described a clear section of tube around the worm where it had broken through and secreted fresh tube.  It was similar to the upper portion of the same tube and indicated the tube was stationary in the sediment.

Webb's above findings sent me back to studies of marine sediments that show abyssal sediments accumulate very slowly,  The probable near vertical orientation of tubes and stable positioning, their length, and widespread distribution in the abyssal oceans where sediment accumulation rates are often extremely slow supported a conclusion that the worms reached great age.  Cold temperatures and low food supply seemed to support the idea of very slow growth when I put a question mark at the end of the title in a short paper, "Pogonophora: the oldest living animals?" published in 1968.

Studies suggesting verification of extreme age of pogonophorans.

Multiple studies found various indications of probable slow metabolism in the deep sea.  One of the most dramatic was the very low rate of bacterial metabolism indicated by the excellent condition of food after eight months in the submarine "Alvin" before  its recovery related by Jannasch et al. in 1971.

A recent post about ocean circulation showing the thousands of year needed for polar water to reach the surface indicates very slow respiratory rates in the deep sea.  It is more dramatic when you see many locations have high numbers of brittle stars in the photos illustrating Heezen and Hollister's 1971 book, The Face of the Deep.

Questions about nutrition of pogonophorans make the absorption of nutrients from pore water in the sediments a likely answer since Southward and Southward (1982) have shown that they can absorb nutrients from water where the concentration is as low as that found in deep sea sediments.

Studies suggesting the pogonophorans are the missing link.

I am embarrassed that I was so slow to see the pogonophorans as the link between protostomes and deuterostomes.  I was quite content with the posterior segmented body section discovered by Webb and the possession of chitin as reason for their polychaete ancestry.  The report of Gans and Northcutt in 1983 that developmental features of pogonohorans put them among the deuterostomes was unbelievable.  My distress was short-lived when I thought it was impossible unless they were an intermediate form; all the answers seemed to pop into my head- how that would explain the inversion, the changed embryology, and the hemichordate resemblance.

There are many more features of advanced protostomes and deuterostomes made understandable by common ancestry instead of convergent evolutionary origin,  The different evolution rates possible are also well illustrated by understanding the pogonophoran's evolutionary position.  My isopod study, teaching a broad range of biology courses, and having to write a new section on pogonophora, provided needed background for discovery of the important evolutionary role for the supposed evolutionary dead-end, the Pogonophora.


Joseph G. Engemann    Emeritus Professor of Biology, Western Michigan University, Kalamazoo, Michigan      July 27, 2018

DISCOVERY

TYPES OF DISCOVERY

Serendipity

Many discoveries are due to chance or an unexpected observation.  Such discoveries are more likely to occur if the observer is alert to the environment.  How many people noticed a zone of no bacterial growth adjacent to a mold colony before Sir Alexander Fleming did, but did not pause to consider the cause? Fleming's discovery of penicillin's inhibition of bacteria provided the model for discovery of many additional antibiotics.

Planned

The search for additional antibiotics was a logical expansion of the serendipitous discovery of penicillin.  Targeted research is common in the research and development units of many companies.  Universities used to be primarily focused on basic research that might, or might not, have commercial application.  Now, research faculty have one eye on the potential valuable uses that might sway granting agencies to provide greater monetary support.

Unrecognized

Recognition of value of research can escape others, especially when it is novel and/or goes counter to accepted thinking of leaders in the subject area.  The significance of Mendel's studies of inheritance in peas was not given much recognition until thirty some years later when it complemented the understanding of chromosomes in genetics.

I think it may be thirty years after I die before zoologists and evolutionary biologists will become aware of how (1) extreme age is a characteristic of abyssal organisms, (2) the stable deep-sea environment provided a refuge for survival during celestial bombardment by asteroids etc. during the early history of life on earth, (3) one such surviving group was the Pogonophora which (4) show the embryological and morphological connection of protostome ancestors to deuterostomes such as vertebrates, and (5) illustrate the error of ancestral trees that ignore the effects of generation time in calculating branching patterns.

The five points mentioned have been discussed in earlier posts of this blog and may be enough to help some curious scientist of the future to set the record straight.  Much of the information can be found in a hypothetical discussion of invertebrates in the final chapter of the 1981 3rd edition of Engemann and Hegner's Invertebrate Zoology published by Macmillen Publishing Company.  Points 4 and 5 were arrived at shortly after I realized the theory proposed in the final chapter represented reality.

At eighty-eight I do not expect to be here for nearly as long as the twenty years I have been retired.  And low energy and memory lapses are more frequent.  I think I have included the basics of what is important in my work in this blog.  So now I may go to some unpublished work of mine of less consequence to the accurate understanding of evolution.  In fact, I had started one on eyelines and coevolution when it disappeared with a wrong keystroke.  I have typed this with greater care and have to get my computer's word-processing and photo programs fixed so I can work more efficiently.  If you have read this far, thank you.

Joseph Engemann,  Emeritus Professor of Biology, Western Michigan University, Kalamazoo.  January 12, 2017

EVOLUTION IN THE DEEP SEA

ORIGIN OF DEUTEROSTOMES BACKGROUND

EXTREME LONGEVITY IN THE DEEP SEA  

There are deep-sea worms that can possibly live longer than a hundred thousand years.  I became aware of this because of my interest in factors responsible for extreme longevity.  I developed that interest from my (1956-1963) doctoral research on a Tasmanian isopod crustacean that takes three years to reach maturity.  A Michigan species from a related isopod suborder can do so in three months.

 

There are several categories of factors that are responsible for extreme longevity and/or life cycle stage duration differences.  Factors making the deep-sea worm live for thousands of years include.

                Genetics.  This factor is unknown for the deep-sea worm, but is certainly important.  We know insects such as the aphid can produce a generation in a few weeks or less, whereas some cicadas require seventeen years.  Conclusion: the genetic factor can be responsible for great longevity differences.

                Temperature.  In the deep sea temperatures are close to four degrees centigrade year around.  At sea level, temperatures can be more than twenty degrees centigrade higher year around in the tropics.  Many biochemical reactions used by living creatures double in speed for every ten degrees increase in temperature.  The bullfrog may take three years to mature in the northern part of its range, but only need a year in the southern part.  Conclusion: Temperature can be responsible for over two doublings of longevity in the deep sea, over a four-fold difference.

                Extreme pressure.  For partially unknown reasons life processes in the deep sea are greatly reduced.  Depths of 6,000 feet are associated with a 99% reduction of metabolism of bottom communities.  At the pressure of depths beyond 21,000 feet a deep sea bacterium showed a dramatic drop in respiratory rates although other environmental factors were the same.  Conclusion:  abyssal depths could be responsible for a thousand-fold difference in longevity.

                Ecological factors.  These act on the genes through natural selection to make great differences in longevity adaptive to the environment of the organism.  In the comparison I made of Tasmanian and Michigan isopods the magnitude was more than ten-fold within a similar temperature regime.  Conclusion: ecological factors of low food supply, low predation, and stable environment could select for genetics leading to a more than ten-fold increase in longevity.  The pressure and temperature differences noted previously can be multiplied and the result multiplied by this ten-fold increase to make an enormous potential difference for increased longevity of abyssal organisms.

DISCUSSION

Evolution could be so slow in deep sea organisms that ancestral forms could survive relatively unchanged while descendants migrate to surface waters and change greatly into new groups.  Known examples will be discussed eventually, if I live long enough.  But the major one making revision of the tree of life, as envisioned by my peers, necessary is one of the themes of my 2010 unpublished book manuscript (Evolution Insights).  Parts of it may be condensed in future postings.  The next evolution posting is expected to explain how major errors have been made in proposed evolution of major groups because my peers were not aware of the longevity impact suggested above.

EXTREME LONGEVITY IN THE DEEP SEA, was first implied in my 1968 paper (see references below.  It was later treated on pages 717-732, Chapter 14, of Engemann and Hegner, 1981, Invertebrate Zoology, 3^rd edition, Macmillan Publishing Co., New York.  My peers tend to ignore things that are not in major journals, their specialty journals, or monographs.]

Some starting point references, for those reluctant to take my word for it, are:

Brooks, William Keith.  1915.  The Foundations of Biology.  Columbia Univ. Press, New York.  339 pp.   Comments on - the unchanging nature of Lingula (page 219), and p. 217 “the diversity of the Lower Cambrian fauna and of its intimate relation to the fauna on the bottom of the modern ocean”.  See Jablonski et al. below.

Engemann, Joseph G.  1968.  Pogonophora: the oldest living animals?  Pap. Mich. Acad. Sci., Arts, and Letters, 53:105-108.  Extreme age of individuals inferred from published data of others about tube length, probable depth in sediments, and sediment rates of accumulation in abyssal environments.

Ericsson, D. B., M. Ewing, and G. Wollin.  1963.  Pliocene-Pleistocene boundary in deep-sea sediments.  Science, 139:727-737.  Slow rates of accumulation for marine sediments.

Gadgil, Madhav, and William H. Bossert.  1970.  Life historical consequences of natural selection.  The American Naturalist, 104(935):1-24.  P. 12 “thereproductive effort increases with age”; p. 20 “the age for reproduction will tend to increase as the degree of satisfaction or the availability of resources decreases.”

Ivanov, A. V.  1963.  Pogonophora. Consultants Bureau, New York.  479 pp.  This major monograph on the pogonophorans was published prior to the discovery of their giant tubeworm relatives at thermal vents.

Jablonski, David, J. John Sepkoski, Jr., David J. Bottjer, and Peter M. Sheehan.  Onshore-offshore patterns in the evolution of Phanerozoic shelf communities.  1983.  Science, 222:1123-1125.  Fig. 1 shows older groups from shore area are now found in deeper water, older Ordovician inner shelf forms now on outer shelf, Cambrian shore forms now on slope and deeper. Consistent with comment of Brooks, 1915.

Jannasch, H. W., et al.  1971.  Microbial degradation of organic matter in the deep sea.  Science, 171:672-675.

Smith, K. C., and R. R. Hessler.  1974.  Respiration of benthopelagic fishes: in situ measurements at 1850 meters.  Science, 184:72-73.

Webb, M.  1964a.   The posterior extremity of Siboglinum fiordicum(Pogonophora).  Sarsia, 15:33-36.  Fig. 1, page 34, shows “anchor” with 17 setae bearing annulations.  This seldom recovered portion of the worm may be so because the tube portion it is in is deep in the sediments consistent with vertical orientation of the tube.

Webb, M.  1964b.  Tube abnormality in Siboglinum ekmani, S. fiordicum andSclerolinum brattstromi (Pogonophora).  Sarsia, 15:69-70.  When worm posterior protrudes through break in tube it secretes a new posterior tube portion with no annulations but is continuous with anterior portion of the tube and sealed off from old posterior portion; Fig. 1, page 69 shows it for three species. 

Yayanos, A. A., A. S. Dietz, and R. VanBoxtel.  1979.  Isolation of a deep-sea barophilic bacterium and some of  its growth characteristics.  Science, 205:808-810.  It showed rapid depression of growth beginning at depths with pressures exceeding 725 atmospheres. 

This post may have been lost or not published.  I just relocated it and as it is important to the topics I was about to address, I thought I should try to re-post it.  
Joseph G. Engemann, June 22, 2013