Anyone know the natural boundary between northern and coppernose in the Florida panhandle?

From observations the bluegill in the Apalachicola is not coppernose and bluegill in the Suwannee River drainage are coppernose. I have no experience with bluegill of the major intervening drainages (New, Ochlockonee, Steinhachee).

This is a passage from a book chapter I wrote with Jeff Koppelman. The book is on centrarchids and is being published by Blackwell Scientific, and should be out in May 2008.

There is a degree of uncertainty as to how many subspecies of Lepomis macrochirus are recognized. The problem centers on Pomotis speciosus described from Brownsville, Texas by Baird and Girard (1854). This species was subsequently synonymized with L. macrochirus by Hubbs (1935). At a later date, Hubbs and Lagler (1958) treated Pomotis speciosus as a subspecies of L. macrochirus, concluding that the geographic range is throughout Texas and northeastern Mexico. Allozyme analyses did not detect genetic differentiation between L. m. macrochirus and L. m. speciosus (Kulzer and Greenbaum, 1986), and subsequent treatments of centrarchid species diversity have not recognized L. m. speciosus (Gilbert, 1998).
The two valid subspecies of L. macrochirus present an interesting problem of nomenclature confusion, morphological and genetic divergence, an area of presumed secondary contact and introgression, and a biogeographic pattern and a timing of divergence seen in another centrarchid sister species pair. The nominal subspecies L. m. macrochirus Rafinesque is distributed across eastern North America except for the northern Atlantic Coast (Lee, et al., 1980), while the other subspecies is endemic to the Florida Peninsula (Felley, 1980). Initially, the subspecies found in Florida was designated as L. m. purpurescens Cope under the premise that this subspecies extended from Atlantic Coast of the Carolinas to the Florida Peninsula (Hubbs and Allen, 1943; Hubbs and Lagler, 1958). The type locality for Lepomis purpurescens is in the Yakin River Drainage in North Carolina (Cope, 1870). Subsequent morphological and molecular analyses demonstrate that this is far north of the range of the Florida subspecies (Avise and Smith, 1974a; Felley, 1980; Avise, et al., 1984), and as Gilbert (1998) has pointed out, Cope described a Bluegill from Florida, Lepomis mystacalis (Cope, 1877). Therefore, the appropriate name for the Florida Bluegill is L. macrochirus mystacalis.
Lepomis m. macrochirus and L. m. mystacalis are morphologically and genetically distinct, but there is a presumed area of introgression via secondary contact along most of southern Georgia and South Carolina (Felley, 1980; Avise, et al., 1984). Another sister-species pair in Centrarchidae, Micropterus salmoides and M. floridanus, exhibit a very similar distribution and area of secondary contact and introgression (Bailey and Hubbs, 1949; Philipp, et al., 1983). Based on a fossil calibrated molecular phylogeny of Centrarchidae, the divergence time between M. salmoides and M. floridanus is approximately 2.8 million years ago (mya) (Near, et al., 2003; Near, et al., 2005b). Lepomis m. macrochirus and L. m. mystacalis exhibit a very similar divergence time. We found mtDNA cytochrome b gene sequences on Genbank for five individuals of L. m. macrochirus and a single L. m. mystacalis (accession numbers, AY115975, AY115976, AY225667, AY828966, AY828967, AY828968). The average genetic distance between these two subspecies was 4.5%, which translates to a divergence time of roughly 2.3 mya (Near, et al., 2003). Future work should aim towards gathering sufficient morphological and molecular data to more precisely determine the geographic distribution of these two forms and assess if L. mystacalis is a valid species.

TomNear,

I agree the northern and coppernose bluegills are very different. We have about 20 wild caught individuals from each of at least 8 localities from each "subspecies" range. Some distinctions can even be made even within the coppernose. There may be differences even between stocks of coppernose. From what I know of drainages in Florida, many bluegill populations may have been out of contact for very long periods and many clearly provide different challenges to inhabiting fishes. The differences within coppernose, especially where coloration and body conformation are concerned , are maintained with F1 tank reared fish. Even though northerns and coppernose hybridize in a pond setting, we do have difficulties getting hybridization to go in a tank setting. The male coppernose do not "spin-up" for northern females but will do so readily for coppernose females. Male northerns not so discriminating.

Still not getting information about boundaries on a stream basis. The hand-paint bluegill which occurs within what I understand to be the introgression zone between northern and southern bluegill doe not appear to be an intergrade. They are sympatric with other endemics within the Apalachicola drainage. Something interesting is going on.

As for the southwestern bluegill. I am skeptical about its non-existence. Despite its "recognized" taxonomic status we made collections from locations with likely minimal overstocking with northern and coppernose bluegills. Kulzer and Greenbaum (1986) do not appear to have made such efforts. Conversations with old time bait dealers were very strong promoters checking ourselves. The southwestern bluegill we retrieved look mostly like northern bluegill but are among other differences much smaller even when reared under similar conditions. If they can not be distinguished from northern bluegill, then at least they are pygmy version.