|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 4. Evolutionary reconstruction of the Root effect in jawed vertebrates. The
underlying phylogenetic tree is based on the species and branching pattern
shown in Fig. 3. The Root
effect has been colour coded and its magnitude in ancestral species has been
reconstructed on the z-plane of the structure by linear parsimony
from values measured in living species as shown in
Fig. 1. (A) The
three-dimensional structure has been rotated to visualise the gradual increase
of the Root effect in early ray-finned fishes (nodes c–f) after their
ancestors diverged from the lineages of sharks (a) and lobe-finned fishes
(including tetrapods, b). The red bar indicates the origin of the choroid rete
mirabile in the branch leading to the bowfin and teleosts only after the Root
effect had increased. (B) Enlarged part of the structure in A after rotation,
showing two examples of secondary reductions of the Root effect in
Ostariophysi. The Root effect is only ever reduced when the choroid rete
mirabile has been lost. The latter is indicated by red bars. The oriental
weather loach still has a swimbladder rete mirabile, whereas the two catfishes
lack both types of rete (Fig.
3), consistent with a complete loss of the Root effect in the
latter group. Ma, million years. Modified from Berenbrink et al.
(Berenbrink et al., 2005).
|
