There May Be 5 Species of Shoal Bass Previously Described as 1

New discoveries await those entering the field of biological research.  Scientists have uncovered volumes of knowledge, yet we still know so little.  Nevertheless, it’s surprising that in Georgia, in the midst of what most would consider an advanced civilization,  there may be as many as 5 distinct species of bass left undescribed by science.  Byron Freeman and other scientists are using anatomical and DNA comparisons to remedy this unlikely gap in ichthylogical classification.

 

Redeye bass.  There may be 5 different species of shoal bass wrongly considered the same species.

Shoal basses; along with largemouth bass, crappies, and sunfish; belong to the Centrarchidae family.  Shoal basses favor rocky stretches of river too warm for trout, yet too cool for largemouth bass, though there is some overlap on both ends.  Dr. Freeman discovered that various specimens of a species of shoal bass, known as the redeye bass (Micropterus coosae), differed strikingly, depending upon which river they came from.  By comparing 20 anatomical characteristics, Dr. Freeman was able to determine that shoal basses from the Coosa, Apalachicola, Chattahoochee, Savannah, and Altamaha rivers all differed from each other enough to be considered separate species.  Differences in shoal bass DNA sequencing supports his discovery. The scientific name, Micropterus bartrami, or Bartram’s bass, has been proposed for a species living in the Savannah River.

All of these species share a close evolutionary relationship.  It’s likely the founding population of shoal bass became geographically isolated due to stream capture events when the headwaters of 1 stream eroded backwards and captured the flow of another. For example a tributary of the Savannah River captured a tributary of the Chattahoochee, explaining how speciation occurred between shoal basses from these 2 rivers.  (See:https://markgelbart.wordpress.com/2014/02/06/tallulah-gorge/) Similar geological events probably explain the evolutionary divergence of other shoal basses.

All of these species hybridize with each other, showing the difference between species is a gray area.  Hybridization via backcrossing is another way new species can originate.  By introducing a species of shoal bass into another species of shoal bass’s range, man may inadvertently create a new species.  However, scientists are concerned that introductions of smallmouth bass into shoal bass habitat will result in the latter’s extinction.

See also: https://markgelbart.wordpress.com/2013/04/26/the-evolutionary-history-of-the-black-bass-genus-micropterus-sp/

Reference:

Freeman, Byron; et. al.

“Shoal Basses, a Clade of Cryptic Identity”

Black Bass Symposium 2013

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