BioSystems 56 2000 43 – 53
Studies into abstract properties of individuals. IV. Emergence in different aged needle primordia of Douglas fir
Jack Maze
a,
, Kathleen A. Robson
b
, Satindranath Banerjee
c
a
Department Of Botany, Uni6ersity Of British Columbia, Vancou6er, B.C., Canada V
6
T
1
Z
4
b
Robson Botanical Consultants,
14836
NE
249
th Street, Battle Ground, WA
98604
, USA
c
Scientificals Consulting,
309
–
7297
Moffatt Road, Richmond, B.C., Canada V
6
Y
3
E
4
Received 30 November 1999; received in revised form 17 January 2000; accepted 21 January 2000 Dedicated to the memory of ‘Spence’, Alden Alva Spencer Jr.
Abstract
Young, middle aged and older Douglas fir needle primordia, as determined by distance from the apical meristem, were measured and analyzed to compare levels and patterns of emergence related to development time. Emergence
was seen in the differently aged needle primordia, generally most noticeable in the oldest and the least apparent in the youngest. There was also a negative relationship between variation in size and degree of emergence, and a positive
one with variation in organization. The increasing level of emergence that appears with age can be related to the continual expression of information and the concomitant increase in complexity that marks ontogeny and is the result
of diverging developmental trajectories. The histogenetic events seen in ontogeny can be interpreted as ‘clocks’ generating local time through the interactions among cells and tissues that make up the needle primordia. Emergent
properties are manifested through the local events that mark ontogeny, and also through the expression of phylogenetic information, or the local expression of global historical levels of organization. © 2000 Elsevier Science
Ireland Ltd. All rights reserved.
Keywords
:
Emergence; Complexity; Ontogeny www.elsevier.comlocatebiosystems
1. Introduction
This paper is part of a continuing series Maze and Bohm, 1997; Maze, 1998, 1999 the ultimate
goal of which is an exploration of the nature of the relationship between ontogeny and phylogeny.
A first step in this exploration is the description of empirically based properties common to ontogeny
and phylogeny. Once those properties are estab- lished they can be used as guides in a search for a
common conceptual and theoretical framework for ontogeny and phylogeny.
Some sort of relationship between ontogeny and phylogeny has long been apparent. Both
events involve irreversible changes that occur over
Corresponding author. Tel.: + 1-604-8222133; fax: + 1- 604-8226089.
E-mail address
:
jmazeinterchange.ubc.ca J. Maze 0303-264700 - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved.
PII: S 0 3 0 3 - 2 6 4 7 0 0 0 0 0 7 0 - 8
time. It is through ontogeny that the changes which result in phylogenetic pattern are expressed.
Ontogeny and phylogeny are the phenomena through which organic form, the part of the bio-
logical world available to most people, unfolds. The study of the relationship between ontogeny
and phylogeny can even be seen in early evolu- tionary thought through Darwin’s recapitulation-
ist views Richards, 1992. What we want to do is explore the relationship between ontogeny and
phylogeny beyond these truisms.
In our search for characteristics to use in ex- ploring ontogeny and phylogeny we rely upon a
concept of emergence. In so doing, our first as- sumption is that both ontogeny and phylogeny
result in emergence, or emergent properties. Our second assumption is that emergence is of a suffi-
cient level of abstraction that we can use it to directly compare the products of ontogeny, indi-
viduals, and phylogeny, assemblages of related individuals. Our third assumption is that such a
comparison will allow insight into the most basic features of ontogeny and phylogeny, the concep-
tual and theoretical constructions that bind them together.
The usual presentation of emergence is the bio- logical truism, the whole is more than the sum of
its parts. The credibility of that statement is be- yond doubt. However, there are two prerequisites
for the study of emergence as a means to explore ontogeny and phylogeny. The first is a reformula-
tion of that truism which will allow its empirical analysis. Second is the establishment of an analyt-
ical protocol that will allow direct comparisons between the products of ontogeny, individuals,
and phylogeny, groups of related individuals. This second prerequisite is especially important be-
cause it establishes a common language to use in talking about ontogeny and phylogeny. A com-
mon language is necessary in order to seek the common theories and concepts in phenomena that
result in things as complex as organisms.
In the studies done to date Maze and Bohm, 1997; Maze, 1998, 1999 the depiction of emer-
gence used is that of Polanyi 1958; namely, that higher hierarchical levels wholes have properties
not seen at lower levels parts, the properties at the higher level having emerged from the lower.
Or, the description of lower hierarchical levels are inadequate to characterize the higher. This char-
acterization also allows us to establish an analyti- cal
protocol for
comparing the
different hierarchical levels, parts and wholes. First, we can
establish a common descriptive morphological language for different hierarchical levels through
comparing different levels made up of more inclu- sive groups of like-sized items. In the previous
studies Maze and Bohm, 1997; Maze, 1998, 1999 the like-sized items used were grass spikelets the
first two studies or needles of Pinus ponderosa Lawson the third study, and the different hierar-
chical levels were of smaller and larger aggrega- tions of those parts. This is, of course, the
equivalent of the Linnean hierarchy where higher levels are comprised of more and more inclusive
groups of individuals. Second, we can characterize those different levels by describing features logi-
cally independent of the levels themselves, the organization that they show, and then use those
descriptions of organization in an analysis of emergence. What relying on Polanyi’s 1958 char-
acterization of emergence allows is to calculate the degree of emergence seen in individuals the
difference between lower and higher hierarchical levels within individual levels and that seen in
aggregations of related individuals the difference between lower and higher hierarchical levels
within the group being analyzed Polanyi, 1958. It is that degree of emergence that offers us the
common language necessary to explore the rela- tionship between ontogeny and phylogeny; the
common language is degree of emergence, the exploration comes through a comparison of indi-
viduals and groups of related individuals.
In one study of grasses Maze, 1998 evidence was presented for a time-related increase in the
degree of emergence, seen as the difference be- tween the lower and higher levels of a two-tiered
hierarchy. However, time in that study was the inferred time of evolution. Degrees of emergence
were presented as a continuum, with the lowest level being in ‘youngest’ groups, populations, and
the greatest emergence shown in the ‘oldest’ group, a phyletic lineage consisting of two closely
related species, Achnatherum hendersonii Vasey Barkworth and A. wallowaensis, Maze and Rob-
son. The group presumed to be of ‘intermediate’ age, species, expressed an intermediate level of
emergence. The demonstration in that paper of a possible
relationship between phylogenetic time, which is only inferred, and the degree of emergence raises
this question: is there a similar relationship be- tween the degree of emergence and time when
time is assessed by the real time of development? More specifically, will older needle primordia
show a greater degree of emergence than younger? That is the purpose of this paper, to report on an
analysis of emergence in an ontogenetic study of differently aged needle primordia of Douglas fir
Pseudotsuga menziesii Mirb. Franco.
A broader and more abstract way to envision the real time of ontogeny consists of starting with
the histogenetic events that occur during needle development; the division, differentiation and
elongation of cells in the needle primordia. As these cells mature, they act as ‘clocks,’ ‘clocks’
referring to a means to measure or perceive time, creating their own local time as they interact with
other cells and respond to previous stages as ontogeny progresses. Histogenetic events occur-
ring later in the process reference earlier steps in development, or, the cellular communication
through which development is coordinated gener- ates local, asymmetric unidirectional time Mat-
suno, 1988. The many cells, behaving as ‘clocks’ when they interact with other cells, form the
integrated unit we recognize as a conifer needle primordium. A needle primordium, when used as
a point of reference, can also be viewed as a higher level ‘clock’ comprised of many component
‘clocks’ formed from individual cells and tissues. This communication, through which form un-
folds, also references ‘global,’ or ‘in the record’ phylogenetic information that exists because of
the unique history of Douglas fir as a species, as a conifer, and as a vascular plant Matsuno, 1988;
Matsuno and Salthe, 1995. In the context of this study, the initiation of a needle primordium starts
a ‘clock’ which forms the reference for subsequent ‘clocks’ that appear with more ontogenetic events.
As more needle primordia are initiated, they refer- ence the ‘clocks’ generated by events that pre-
ceded them. Upon reaching some threshold, the primordia move beyond a generalized mass of
cells and form a structure that is distinctively a Douglas fir needle. Matsuno’s approach to view-
ing ontogeny local scale and phylogeny globally encompassing as different tiers or sets of time
emphasizes the hierarchical nature of biological organization Matsuno, 1988. This view includes,
but is not limited or reduced to, the expression of genetic information. Parts of a bud rely on the
‘clocks’ within a bud, the buds on a tree rely on ‘clocks’ established within a tree, a tree relies on
the ‘clocks’ that existed in its parents and so on back through its phylogenetic history. The reverse
process does not occur, that is, phylogenetic time does not reference local, developmental events
because it is part of the historical record. Thus, what we are studying here, while it is focused on
needle primordia in buds, is part of an integrated series with a long history. Using these concepts of
time serves to emphasize the historical interrelat- edness of all botanical structures. As well, these
self-same concepts identify the kind of compari- sons Goethe identified as the holistic approach
necessary to understand botanical events Arber, 1946.
2. Materials and methods
