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Warm Microgradients Elicit Adaptive Behavior in Isotropically Cooled, Inert Populations of Oxytricha bifaria (Ciliophora, Hypotrichida)
Author(s) -
BARBANERA FILIPPO,
ERRA FABRIZIO,
RICCI NICOLA
Publication year - 1999
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.1999.tb06071.x
Subject(s) - biology , thermal , population , temperature gradient , isotropy , astrophysics , mechanics , biological system , physics , optics , thermodynamics , meteorology , demography , sociology
In order to investigate the physiological potentialities of behaviorally inert Oxytricha bifaria , cooled from 24 to 9° C according to an already standardized protocol, a warm microgradient was created in the experimental chamber and the behavior of ciliates was analyzed both at the level of the passing warm wave front (dynamic microgradient), and, afterwards, when the thermal gradient stabilized (static microgradient). We monitored the general behavior of the experimental populations by means of (i) their centroid, (ii) the ethograms of single oxytrichas, and (iii) calculating the numerical indices and rates of their creeping tracks. It was found that (a) the population moves towards the heating source, (b) the oxytrichas react immediately to the thermal stimulus, (c) creeping forwards (d) at very high velocity (e) along uninterrupted looping tracks (f) according to precise mechanisms of positive/negative orthokinesis, thus orientating towards the environmental optimum. Moreover, (g) the ciliates accumulate in the warmest area, correcting their creeping by means of many specific behavioral patterns (the Side Stepping Reaction) once the gradient is stabilized. At 9° C, despite their inertness, the ciliates are still able to behave adaptively reacting immediately and orientatedly, once a directional factor (the thermal gradient) arises in an isotropic environment.