Genetic evidence for two species in the C. bifurcatus of Wülker et al. (2009).

The data of Proulx et al. (2013) suggested that the species may comprise two closely related components.  Additional data, mostly from GenBank, confirms there are distinct base differences between the groups at 10 bases (see Table below).

Locality
# specimens
base no.
 
 
1 2 3 3 3 4 4 5 5 6
 
 
9 7 3 4 8 7 9 1 6 2
 
 
7 1 6 2 1 7 8 6 4 1
Group 1
 
 
Halifax NS
1
C C T T A T C C A ?
L. D'Allembert QC
1
C C T T A T C C A A
L. Adéline QC
2
C C T T A T C C A A
L. Arnoux QC
1
C C T T A T C C A A
L. Duprat QC
4
C C T T A T C C A A
L. Opasatica QC
3
C C T T A T C C A A
L. St Joseph QC(07)
1
C C T T A T A C A A
GeoBayIsNP ON
1
C C T T A T A C A A
Algonquin Pk ON
1
C C T T A T C C A A
Ottawa ON
1
C C T T A T C C A A
London CCHS ON
1
C C T T A T A C A ?
London OSS ON
1
C C T T A ? ? ? ? ?
Sudbury ON
2
C C T T A T C C A A
ElkIs NP AL
1
C C T T A T C C A A
Pleasant L. MA
1
C C T T A T C C A A
Kaibab Nat.For. AZ
1
T T A T A T A C A C
Group 2
 
 
Pr.Ed.Is NP. PEI
1
T A A C T A T T A ?
L.St Joseph QC(06)
3
T G A C T A T T T C
L.Kinojévis, QC
1
T G A C T A T T T C
McFarlane L. ON
3
T G A C T A T T T T
Tilton L. ON
1
T G A C T A T T T T
Kawatha ON
1
T G A C T A T T T C
Kawatha ON
2
T G T C T A T T T T
Brockville ON
1
T G A C T A T T T ?
Kitchener ON
1
T A A C T A T T A ?
London BSPS ON
1
T T A C T A T T A ?
London ABLSS ON
1
T A A C T A T T ? ?
Meaford CS ON
1
T A A C T A T T A ?
Peterborough ON
1
T A A C T A T T A C
Puslinch Twn ON
1
T A G C T ? ? ? ? ?
Rouge NUP ON
1
T A A C T A T T ? ?
Whitby ON
1
T A A C T A T T ? ?
Madison WI
2
T A A C T A T T A C
Pr.Alf. NP SK
1
T A A C T A T T A C
Grasslands NP SK
1
T A A C T A T T A ?
Gulf Is NP BC
2
T C A C T T T T A ?
Kamloops NAM BC
2
T G A C T A T T T ?
Kelowna CS BC
1
T G A C T A T T T ?
Riffle Ck OR
1
T G A C T A T T T C

Bases that differ between the two groups of C. bifurcatus in the COI tree
? - base unknown in short sequences from BOLD database

DeSalle et al. (2005) suggested that for closely related species, such specific base differences are a better indicator of specific status than distance measures.  Martin (2011) noted some examples amongst the Australian species and the distinction between C. frommeri (sp. 2d) and the other members of the C. staegeri-group is a further example.
Initially the split of COI sequence of specimens identified as C. bifurcatus was recognized in the BOLD database by placing them in separate bins, although BOLD has subsequently amalgamated the two Bins, probably as a result of confusion from shorter Barcodes accepted in the database.  As seen in the Table above (where sequences shorter than 500bp were not included), some of these sequences can be missing up to four of the critical bases.

There is no indication of the two types in the gb2B sequences as there is a very low level of polymorphism overall.

As well there is some suggestion of alternative banding sequences on some chromosome arms (particularly arms B and F) of those relatively few specimens for which both cytology and DNA sequence is available.  Group 1 corresponds to those of the type egg mass (see Table below).

              \Arm
Specimen\
A
B
C
D
E
F
Gmed BR
Group 1
 
 
some C2
 
 
 
 
Pleasant L. MA 21
A2
B1
C1
D2
E1
F1
abs
Algon Pk ON 21f
A3
B1.2
C1
D1
E1
F1
pres
L.Dupret QC 10
A1
B1
 
D1
E1
F1
abs
L.Arnoux QC 11
A1.2
B1
C1
D1.2
E1
F1
abs
L.D'AlembertQC 12
A1
B1
C1
D1
E1
F1
abs
Group 2
 
 
 
 
 
 
 
Madison WI em#8
A3
B2
C1
D2.3
E2
F2
pres
Madison WI em#7
A3
B2
C1
D2
E2
F2
pres
McFarlane L.ON 7
A1
B2
C1
-
E1*
F2
pres
Tilton L.ON 8
-
B2
-
-
E1?
F2
pres
Type material
 
 
 
 
 
 
 
Type egg mass
A1&3
B1
C1
D1
E1
F1
abs
* it is just possible that this is E1.2
Sequences of Chironomus bifurcatus specimens used in COI analysis

It is possible that where the two types occur together there is some level of interbreeding.  For example a specimen from Copanspin Farm, Dunrobin, Ontario had the karyotype A2.3, B1.2, C1.2, D2.2, E1.1, F1.2, G1.1.

For clarification of which is C. bifurcatus, information on specimens from the same egg mass as the Holotype is provided.

[ Return to Index | Return to C. bifurcatus ]


Modified: 4 June 2021
Access: Unrestricted
Copyright © 2013-2021, Jon Martin.