Biology Reference
In-Depth Information
Sunspot
Activities
Climate
Changes
Tree Ring
Patterns
Fig. 15.5 Tree rings can record sunspot activities, because sunspot activities affect climate which
in turn influences tree-ring growth
DNA
Morphologenesis
Environment
Fig. 15.6 DNA and environment as independent cause of the morphology of organisms. The main
question in morphogenesis is: What are the mechanisms by which the combination of DNA and
environment brings about the morphology of organisms. Please note that environment includes
sunspot activities
(i.e., in synchronic time; see Table
15.3
), Fig.
15.6
represents developmental
biology; on the time scale of species life span which may be as long as hundreds
or more life span of the individual members of a species under consideration (i.e.,
diachronic time scale), the same figure can represent evolutionary biology. Thus, it
may be necessary to recognize two kinds of timescales in biology - developmental
(or synchronic) and evolutionary (or diachronic) times - and these timescales may
be said to be
complementary
to each other in the sense that focusing on one
automatically excludes the other from view just as focusing on the wave nature
of light (or forest) automatically excludes the particle nature of light (or trees) from
view in physics and
vice versa
.
We may express this situation as in Statement 15.6:
The biological time is complementary union of developmental (or synchronic) time and
evolutionary (or disachronic) time. (15.6)
Statement 15.6 may also be referred to as the
EvoDevo duality of life
in analogy
to the
wave/particle duality
of light in physics.
Both developmental and evolutionary processes can be represented using
characteristics of development and evolution are summarized in Table
15.5
.
Of course, different species have different life spans, which can range from 1 day
to 10
6
days. So what distinguish synchronic from diachronic timescales are not the
absolute lengths of time measured with a clock as done in physics but rather the
number of replication cycles of organisms which is unique to biology. In other
words, synchronic and diachronic times are measured relative to the unit of the life
span of organisms whereas the conventional time in physics is measured with a
clock
, which naturally leads to the possibility of dividing time into
physical
and
biological
times as schematized in Fig.
15.7
.
