7717

• UCREFRP Catalog Number: 7717
• Author: Rosenfeld, M. J.
• Title: Genetic Analysis of the Colorado River Gila
• USFW Year: n.d.
• USFW - Doc Type: Non-fatal Sampling, Cell Culture, Chromosomal Analysis and Electrophoresis.
• Copyright Material: NO

<,
~,

~. t- _ t;: .,0'

~. "

'_ 11

~

. .

~ ,_." ,_ _.' A>

A~e the th~ee Colo~ado Rive~ mo~phospecies also th~ee

biological species? The limited elect~opho~etic and cytogenetic

evidence is tentatively inte~p~eted to mean that the Colorado

River Gila a~e a closely-related genetic unit sepa~ate from the

Utah chub.

The results may indicate only two biological spe-

cies:

the roundtail chub (with ~nique Chromosome 19 as well as

a unique LDH staining pattern) and the bony tail-humpback chub.

Interestingly~ this division diffe~s from Miller (1946) and Uyeno

(1960) who conside~~ on mo~phological g~ounds~ that the bony tail

and roundtail chubs are more Closely-related and separated from

the humpback chub. With rega~d to morphology~ it is important to

remember the extensive variability that has contrfbuted to

confusion

~'.

wi t,h ,regard

, ,
to categorization of the Colorado River

. Gila.~~'Jhen~f~re, categorization on morphologIcal grounds alone

~.is ,Su.sPeCt:..,~. The
- ~~. ~1': .~' .

differences

in

chromosomal morphology are a

~. . -.

",.

s~rong indicator of the
.~'.

reproductive isolation

of the roundtail

. ~.

chub from the bony tail and humpback chubs.

The LDH fast allele

is further supportive evidence of genetic distinctness.

Whether

or not the bony tail and humpback chubs are distinct species

remains questionable.

Intraspecific

NOR

differences have

been ~eco~ded in other taxa (Winking et al.~ 1980) and the LDH

intensity diffe~ence

coul d somehow ' be envi ~onmentall y- o~

developmentallY-induced ~athe~ than genotypic in origin (Whitt~

1 981 ) .

Howeve~~ the evidence does indicate some kind of genetic

sepa~ation between the bony tall

and humpback chub~ but whether