scholarly journals Electric Fishes

Nature ◽  
1888 ◽  
Vol 38 (987) ◽  
pp. 515-515
Author(s):  
W. H. CORFIELD
Keyword(s):  
2021 ◽  
Author(s):  
Erika L. Schumacher ◽  
Bruce A. Carlson

AbstractBrain region size generally scales allometrically with total brain size, but mosaic shifts in brain region size independent of brain size have been found in several lineages and may be related to the evolution of behavioral novelty. African weakly electric fishes (Mormyroidea) evolved a mosaically enlarged cerebellum and hindbrain, yet the relationship to their behaviorally novel electrosensory system remains unclear. We addressed this by studying South American weakly electric fishes (Gymnotiformes) and weakly electric catfishes (Synodontis spp.), which evolved varying aspects of electrosensory systems, independent of mormyroids. If the mormyroid mosaic increases are related to evolving an electrosensory system, we should find similar mosaic shifts in gymnotiforms and Synodontis. Using micro-computed tomography scans, we quantified brain region scaling for multiple electrogenic, electroreceptive, and non-electrosensing species. We found mosaic increases in cerebellum in all three electrogenic lineages relative to non-electric lineages and mosaic increases in torus semicircularis and hindbrain associated with the evolution of electrogenesis and electroreceptor type. These results show that evolving novel electrosensory systems is repeatedly and independently associated with changes in the sizes of individual brain regions independent of brain size, which suggests that selection can impact structural brain composition to favor specific regions involved in novel behaviors.


2019 ◽  
Vol 59 (2) ◽  
pp. 420-431 ◽  
Author(s):  
Kory M Evans ◽  
Marta Vidal-García ◽  
Victor A Tagliacollo ◽  
Samuel J Taylor ◽  
Dante B Fenolio

Abstract Mosaic evolution refers to the pattern whereby different organismal traits exhibit differential rates of evolution typically due to reduced levels of trait covariation through deep time (i.e., modularity). These differences in rates can be attributed to variation in responses to selective pressures between individual traits. Differential responses to selective pressures also have the potential to facilitate functional specialization, allowing certain traits to track environmental stimuli more closely than others. The teleost skull is a multifunctional structure comprising a complex network of bones and thus an excellent system for which to study mosaic evolution. Here we construct an ultrametric phylogeny for a clade of Neotropical electric fishes (Apteronotidae: Gymnotiformes) and use three-dimensional geometric morphometrics to investigate patterns of mosaic evolution in the skull and jaws. We find strong support for a developmental, three-module hypothesis that consists of the face, braincase, and mandible, and we find that the mandible has evolved four times faster than its neighboring modules. We hypothesize that the functional specialization of the mandible in this group of fishes has allowed it to outpace the face and braincase and evolve in a more decoupled manner. We also hypothesize that this pattern of mosaicism may be widespread across other clades of teleost fishes.


2013 ◽  
Vol 216 (13) ◽  
pp. 2363-2364 ◽  
Author(s):  
R. Krahe ◽  
E. S. Fortune

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