|
61>
<br />COPEIA, 1985, NO. 3
<br />LOISELLE, P. V. 1978. Prevalence of male brood care
<br />in Teleosts. Nature 276:98.
<br />MAKSUNOV, V, A. 1971. Non-annual spawning of
<br />some fishes of Soviet Central Asia. J. Ichthyology
<br />11:192-199.
<br />MEYER, F. P. 1960. Life history of Marsipometra has-
<br />taia and the biology of its host Polyodon spathula.
<br />Unpubl. PhD Thesis, Iowa State Univ., Ames.
<br />OLSON, D. E., AND W. J. SCIDMORE. 1963. Homing
<br />tendency of spawning white suckers in Many Point
<br />Lake, Minnesota. Trans. Am. Fish. Soc. 92:13-16.
<br />PRIEGEL, G. R. 1976. Age and growth of the white
<br />sucker in Lake Winnebago. Trans. Wis. Acad. Sci.,
<br />Arts Lett. 64:132-143.
<br />QUINN, S. P. 1982. Age determination and dynamics
<br />of the spawning effort in a population ofwhite suck-
<br />ers, Catostomus commersoni from the Lake Warner
<br />watershed, Hampshire County, Massachusetts. Un-
<br />published MS Thesis, Univ. Massachusetts, Am-
<br />herst.
<br />RANEY, E. C., AND D. A. WEBSTER, 1942. The spring
<br />migration of the common white sucker Catostomus
<br />c. commersonnii (Lacepede), in Skaneateles Lake In-
<br />let, New York. Copeia 1942:139-148.
<br />REIGHARD,J. 1920. Breeding behavior of suckers and
<br />minnows. Biol. Bull. 38:1-32.
<br />RICKER, W.E. 1975. Computation and interpretation
<br />of biological statistics offish populations. Bull. Fish.
<br />Res. Board Can. 191:75-104,
<br />Roussou, G. 1957. Some considerations concerning
<br />sturgeon spawning periodicity. J. Fish. Res. Board
<br />Can. 14:553-572.
<br />SCHAFFER, W. M. 1974. Selection for optimal life
<br />histories: the effects of age structure. Ecology 55:
<br />291-303.
<br />SCOTT, W. B., AND E.J. CROSSMAN. 1973. Freshwater
<br />fishes of Canada. Bull. Fish. Res. Board Can. 184.
<br />SPOOR, W. A. 1935. On the sexual dimorphism of
<br />Catostomus commersoni (Lacepede). Copeia 1935:167-
<br />171.
<br />SPOOR, W. A. 1938. Age and growth of the sucker,
<br />Catostomus commersoni (Lacepede), in Muskellunge
<br />Lake, Vilas County, Wisconsin. Trans. Wis. Acad.
<br />Sci., Arts Lett. 31:457-505.
<br />STEARNS, S. C. 1976. Life-history tactics: a review of
<br />the ideas. Q. Rev. Biol. 51:3-47.
<br />VERDON, R., AND E. M.AGNIN. 1977, Croissance en
<br />longueur du meunier noir Catostomus commersoni
<br />commersoni (Lacepede) du Lac Croche dans Les Lau-
<br />rentides, Quebec. Le Naturaliste Canadien 104:
<br />187-195.
<br />WILLIAMs, G. C. 1966. Natural selection, the costs
<br />of reproduction, and a refinement of Lack's prin-
<br />ciple. Am. Nat. 100:687-690.
<br />DEPARTMENT OF NATURAL RESOURCES, GAME
<br />AND FISH DIVISION, 2024 NEWTON ROAD,
<br />ALBANY, GEORGIA 31708; AND DEPARTMENT
<br />OF FORESTRY AND WILDLIFE MANAGEMENT,
<br />UNIVERSITY OF MASSACHUSETTS, AMHERST,
<br />MASSACHUSETTS 01003. Accepted 10 Nov.
<br />1984.
<br />Cotuia, 1985(3), pp. 619-624
<br />Unusual Lateral Plate Variation of Threespine Sticklebacks
<br />(Gasterosteus aculeatus) from Knik Lake, Alaska
<br />RICHARD C. FRANCIS, ALAN C. HAVENS AND MICHAEL A. BELL
<br />Lateral plate phenotypes of Gasterosteus aculeatus from Knik Lake, Alaska
<br />form a continuum which cannot be divided objectively to conform to the tri-
<br />morphic lateral plate morph concept in current use. This case indicates the range
<br />of possible lateral plate phenotypes possible in G. aculeatus and brings into
<br />question the general applicability of the lateral plate morph concept and un-
<br />derlying genetic models for lateral plate trimorphism. We consider the possi-
<br />bility that abdominal and caudal keel plate phenotypes are potentially genetically
<br />independent and that a polygenic model for plate phenotypes may be more
<br />appropriate.
<br />Pronounced directional asymmetry of lateral plate number was observed in
<br />specimens with greater than seven plates per side. This asymmetry does not have
<br />obvious functional significance. We suggest that this and other cases of pro-
<br />nounced directional asymmetry may represent stochastic fixation in phylogeny
<br />and thus may be useful characters in systematics.
<br />THE threespine stickleback (Gasterosteus acu-
<br />leatus) is widely distributed in the North-
<br />ern Hemisphere, where it occurs in freshwater
<br />and coastal marine habitats. Three lateral plate
<br />morphs are generally distinguished in fresh-
<br />water populations (Miinzing, 1959; Hagen,
<br />1967; Bell, 1976, 1984): (1) the completely-plat-
<br />ed morph; (2) the partially-plated morph; and
<br />(3) the low-plated morph (Fig. 1). Completely-
<br />plated sticklebacks have a continuous row of
<br />plates covering the entire abdomen, and ex-
<br />tending to the caudal peduncle, where it forms
<br />a keel. Partially-plated fish typically have from
<br />10-20 abdominal plates separated by a distinct
<br />gap from the caudal keel plates. Low-plated fish
<br />have from 0-10 abdominal plates and no keel
<br />(see below). Specimens in most freshwater pop-
<br />ulations can be classified quite nicely within this
<br />framework.
<br />Knik Lake is a freshwater lake adjacent to
<br />Knik Arm of Cook Inlet, Alaska, to which it was
<br />formerly connected. In 1958, a screen was placed
<br />in its outlet to Knik Arm, and in 1968, its con-
<br />nection to Knik Arm was completely eliminated
<br />as a result of road construction. Knik Lake has
<br />a surface area of 20.4 ha of which 9.6 ha is
<br />littoral. It has a mean depth of 5.8 m, the water
<br />is clear (Secchi disc transparency, Z,. = 6 m)
<br />and the bottom is sandy. The pH is about 8.5
<br />and the specific conductance 174 mhos/cm.
<br />Gasterosteus aculeatus is the only fish species pres-
<br />ent, an unusual population of which is the sub-
<br />ject of this report. Aside from representatives
<br />of the three lateral plate morphs described
<br />above, this population contains several inter-
<br />mediate lateral plate phenotypes. Indeed, this
<br />population appears to exhibit a continuum of
<br />lateral plate phenotypes and would be difficult
<br />to partition within a trimorphic framework. We
<br />will argue that the results presented here raise
<br />doubts about the generality of this framework
<br />and all the genetic models proposed to account
<br />for lateral plate phenotypes in freshwater pop-
<br />ulations (M(inzing, 1959; Hagen and Gilbert-
<br />son, 1973a; Avise, 1976; Ziuganov, 1983). An
<br />additional unusual feature of this population is
<br />the directional asymmetry in lateral plate count
<br />for non-low-plated fish. The phylogenetic sig-
<br />nificance of this asymmetry and of directional
<br />asymmetries in general (Hubbs and Hubbs,
<br />1944) are discussed.
<br />MATERIALS AND METHODS
<br />The methods used in capturing and treating
<br />the fish have been described by Bell et al. (1985).
<br />Lateral plates offish stained with alizarin red S
<br />were counted under a dissecting microscope at
<br />20-30x. Total lateral plate counts, including
<br />caudal keel plates, were obtained for both sides
<br />of the body of 99 specimens. No attempt was
<br />made to differentiate between abdominal plates
<br />and caudal keel plates in the count totals, as no
<br />satisfactory objective means could be devised.
<br />C 1985 by the American Society of Ichthyologists and Herpetologists
|