|
<br />'I Hi
<br />
<br />COPEI", 1970, NO.3
<br />
<br />I~ in upper portions o[ main rivers
<br />(C1'een, Colorado) allCl in trihutary rivers
<br />(San Juan, Whitc) whereas clcga/l-' is [ound
<br />(ll~i<< ill main river.~. A fairly large area of
<br />s)'mpatry exists in upper sections o[ large
<br />ri\Trs. In the Green River this area extends
<br />fl"OlII the 1II0uth o[ \Vhile River to, at least
<br />"efore 19G2, Flaming Gorge basin, including
<br />lower Yampa River. Ouly three fish col-
<br />.ed in this sympatrk area appealed 1I10r-
<br />~gically intermediate between rob usia
<br />a 1I'elcg-1lt/s. The taximetrics program in-
<br />di?:tted these fish were quite dif(erent [rom
<br />a II other spC'cimens. One was 1II0St similar
<br />lo rob lis/a, the other two were closer to
<br />""'glll/.{. Fill ray COlllllS alld gill raker IIUIll-
<br />ber (Ta"le 2) of the three fish lie betweell
<br />1I1ean vallles for mbl/sla alld dCgllIlS. They
<br />lIIay be hyhrids. or eXlreme morphologic
<br />variants o( either (orlll.
<br />Cenaillly 110 evidellce of lIIass hyhridiza-
<br />t iOll ex ists. a lid rcprod IIcli,'e isolatioll ap-
<br />1'1':11"5 ('.st;lbJishl'd "I't\\'ccn I'Olmslfl ;lIId
<br />rI"galls, evell when sympatric. Based Oil
<br />morphological and ecological distillctivellcss,
<br />we cOllclude rlrglllls is 1I10re correctly treated
<br />as a filII species. l\lil\('kley :lIld DeacolI (1!IG8)
<br />also listed G. clcgalfs as a Cull species but
<br />g:l\"C 110 supportive dat;-t.
<br />
<br />C. cll'golls alld G. ryl"la
<br />
<br />\Vhereas m/llIs/a ;-tlld c1cgalls ;-tl-e distillctly
<br />s('p;lrat('(I, relationships "etweclI clcgalls alld
<br />(')'f"lII are not clear. Mall)' specimclls lhat
<br />morphologically lnidge the gal' betweell
<br />these two ;-tppeared ill the sllldy (Fig. 4).
<br />Ollly two specimclls or 1:)'/"'" have heell
<br />charauniled ill the litnalure (l\lilkr, I!HG);
<br />thlls illtraspcciric "ari"tioll or this [orlll is
<br />Ullknown. Se\-cr;,I Crill'ri:l "",l;'l,.d 'l\'
<br />l\liller rill' distillgllishillg cYIJiw arc: I) An
<br />;,hl'lIpt Jluch;1I \JUlIlp (nllul'are cyll/'a and
<br />dl'f!,o1/s in Fig. 2): 2) A promillcnt fleshy
<br />SIlOllt alld suhtenllill;1I lIlollth; 3) A small
<br />eye i,l COIlIparisoll 10 either HI/)/ola. or
<br />"'{'gallS; '1) A pcdllllcle dcpth illtenllnli;-tlc
<br />1)('IWeCII llt;,l (If I'IJ/Jlo/a. alld "ll'gall... 'rhc
<br />hump alld SIlOllt cl1;,r"neristics arc key char-
<br />acters. BlIt thc scries o[ a,,;-tilahlc specimells
<br />rallge frolll a typir;l! rkglllls (slllooth hump
<br />alld 110 SIIOllt) 10 :1 "lypir;l!" l)'IJiw (ahrupt
<br />hlllllp "lid IOllg snollt). Therefore it is
<br />difficlIlt to 1'1:1((' " 1I10rl'1lo]ogic limit diag-
<br />JHl.sillg 1I1l's(' j"01"l1l-". .-\S IIH'lllifll1<:d t";ll-licr. It;
<br />ri~h ,,"ilh C'xtITIIH' 11Inrph<dogy \\"('IT (llI~tc..cd
<br />~IS ~I .l.,t"I':lr:llt' \fllit h) tl1(' LI:--.:illl('lrics I'rogr;llIl.
<br />
<br />Therefore, we consider theS(' Ilj [ish tn 11l~
<br />c)'I//1lL although superficially some spedmclI'
<br />canllot be distillguished from members of thl'
<br />eh:gnT/s X C)'fJ/Ul subcluster.
<br />The last three le\'cIs of the progr;lIl1 ill
<br />dicate rather strollgly that cYI,lta ami c!"g,lIIt
<br />an' IWo separate entities; howe\'er, the)' all'
<br />wmpletdy hddged hy a third gWlIp ..I
<br />specimclls. This illtergrade cluster does 11111
<br />show the illlcmal homogelleit)' o[ thc othl'l
<br />IWo. Some of its membcrs are most similal
<br />to dr-gaT/s, while others are most similar ,,,
<br />()'IIIIII. Tahle 2 illustr;-ttes the SQmewh:1l
<br />ohscure distinction between clCgllll.t amI
<br />l)'fJiIll alld the position o[ intergrades ill
<br />/IIerislil: l:ltaraners. Spel:illlells sLmlied ill-
<br />dicate a hroad illtergralling series f,,""
<br />"legllllI 10 c)'1111II alld do 1I0t permit a de;ol'
<br />011 sep;-tralioll o[ the two (on liS. SiglliricalHl'
<br />of the illtergr;-tlles is 1I0t 1I0W kllowlI. -IIII~
<br />IIIOSt pl"O/'a/"e explallalioll i,~ illcOIllplel{'
<br />Spe{ialioll allll sllbse'luelll illtrogressi\'e h)'-
<br />/'ridizat iOIl. But the complex lIIay r('pH'sl'llt
<br />olle varia hie specics or two spccies with ,he
<br />illlergrades lJcillg ";-triallls o[ OIlC or the
<br />other. Therefore, we use the term "illln.
<br />grade" i IIslead of hyhrid 10 describc tIK'I'
<br />SI'CClIIICIlS.
<br />Thc large Illnllber o( illtergr;-tdes ill th('
<br />I.ake 1'0"'<:11 area lIIay rdlccl hybridilatioll
<br />leslIlI illg 1'10111 gTeat hahitat changes neatl'll
<br />hy (:lcll CallyolI Dalll. H lhis wne so. 01ll'
<br />woul,l e-"pen 1II0rc ekgllll.\' to be pn'Sl'1I1
<br />allll hylllids to he IlIorphologi, ally lIIid-",;o)'
<br />betweell CkgllllS alld 1.)'11/111 rather thall ;011
<br />illlergl-.lllillg series. 11;,hit<lt dlallges wuul,1
<br />1I0t e"plaill illlcrgralles fllllll Ilpper GrCl'1I
<br />Rin....
<br />TIle r"Cl thai cYIJlI/l is all c1usi\'c emil)'
<br />dill'S not seCl1I appalent ill the lilCl:tllllT,
<br />'I'he reasoll is that 1(:\, collcctiolls han' hel'lI
<br />made ill alea" 1.)'11/,(I mOl)' illhabit. therclore.
<br />[CW C)'I'/1Il or extrcme t)'pes have beell (01-
<br />kned. Gaurill rl al. (19l;U) reported collnt
<br />illg I!J (1'fJlw from Ilicleollt Flat of (;rcl'lI
<br />River, 1I0\\' ullder F1:lIllillg (:orge Rescf\'oil.
<br />These fi511 were ulI;I\'ailahle lor exalllill:uioll
<br />hy the allthors. They I"ohabl)' represelll
<br />illtergrades rather lhall 'J/,IIII ;;~ Ildillnl h)
<br />lhe laximelrics program. This statelllclll is
<br />basl'(llllI specimells used ill lhis study from
<br />"1'1'er (;r<:ell River ;-tlld I' Will a photogr;ll'h
<br />(l\lilln, I!Hi3) Ihal prob;ohly represellls 011('
<br />,,1' th,'xc lish. 11 ;'I'I"':IIS lh:ll ,oll<-( lors ':III
<br />distillgllish 'I"ite e;"il\' h('t"'('('1I "/i',!!,I/IIS :11,,1
<br />fj,h \\.;th a 1l10lT \"'1 "'11'" ",oll'holll):\. Inlt
<br />
|