Interplanetary transfer of photosynthesis: an experimental demonstration of a selective dispersal filter in planetary island biogeography.
We launched a cryptoendolithic habitat, made of a gneissic impactite inoculated with Chroococcidiopsis sp., into Earth orbit. After orbiting the Earth for 16 days, the rock entered the Earth's atmosphere and was recovered in Kazakhstan. The heat of entry ablated and heated the rock to a temperature well above the upper temperature limit for life to below the depth at which light levels are insufficient for photosynthetic organisms ( approximately 5 mm), thus killing all of its photosynthetic inhabitants. This experiment shows that atmospheric transit acts as a strong biogeographical dispersal filter to the interplanetary transfer of photosynthesis. Following atmospheric entry we found that a transparent, glassy fusion crust had formed on the outside of the rock. Re-inoculated Chroococcidiopsis grew preferentially under the fusion crust in the relatively unaltered gneiss beneath. Organisms under the fusion grew approximately twice as fast as the organisms on the control rock. Thus, the biologically destructive effects of atmospheric transit can generate entirely novel and improved endolithic habitats for organisms on the destination planetary body that survive the dispersal filter. The experiment advances our understanding of how island biogeography works on the interplanetary scale.
Cockell
Charles S
CS
Planetary and Space Sciences Research Institute, Centre for Earth, Planetary, Space and Astronomical Research, Open University, Milton Keynes, United Kingdom. c.s.cockell@open.ac.uk
Brack
André
A
Wynn-Williams
David D
DD
Baglioni
Pietro
P
Brandstätter
Franz
F
Demets
René
R
Edwards
Howell G M
HG
Gronstal
Aaron L
AL
Kurat
Gero
G
Lee
Pascal
P
Osinski
Gordon R
GR
Pearce
David A
DA
Pillinger
Judith M
JM
Roten
Claude-Alain
CA
Sancisi-Frey
Suzy
S
D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism; D017753:Ecosystem; D018559:Exobiology; D005118:Extraterrestrial Environment; D055593:Geological Phenomena; D005844:Geology; D010788:Photosynthesis; D013026:Space Flight