Gerald R. Smith

Tetraploid Origin of the Karyotype of Catostomid Fishes

Catostomid fishes appear to have 2n(→4n?) ≃ 100 chromosomes. The Cyprinidae, from which catostomids probably diverged before the Eocene, usually have 2n = 48 or 50 chromosomes. Preliminary cytophotometric measurements indicate an approximate doubling of DNA content of cells among catostomids.

Phylogeny of the Pacific Trouts and Salmons (Oncorhynchus) and Genera of the Family Salmonidae

Abstract Seven genera—Brachymystax, Acantholingua, Salmothymus, Hucho, Salvelinus, Salmo, and Oncorhynchus—make up the living Salmoninae. Relationships of 33 extant and 4 fossil salmonid species and subspecies were studied on the basis of 119 characters analyzed by parsimony algorithms. Twelve equally parsimonious trees each requiring 253 steps were calculated. Monophyly of recognized genera is consistent with all 12 estimates. The earliest branch of the family Salmonidae is the subfamily Coregoninae. Its sister group is the clade including the Thymallinae and Salmoninae. Within the Salmoninae, Eosalmo, from the Eocene of British Columbia, is the sister group of all living genera, as previously shown by Mark Wilson. The living Asian species Brachymystax lenok is the sister species of all other living Salmoninae, as documented by Carroll Norden. Three species of archaic trouts from the Mediterranean area—Acantholingua ohridana, Salmothymus obtusirostris, and Salmothymus (Platysalmo) platycephalus—branch of...

The Classification and Scientific Names of Rainbow and Cutthroat Trouts

Abstract Two unambiguous discoveries involving rainbow trout require scientific name changes. First, the rainbow trout has been demonstrated to be the same species as the Kamchatka trout. Second, studies of osteology and biochemistry of trout and salmon show that rainbow and cutthroat trout, and their close relatives, the golden, Mexican golden, Gila, and Apache trouts, are more closely related to Pacific salmons (Oncorhynchus) than to brown trout and Atlantic salmon (Salmo). The different names required by these two discoveries will cause some confusion in communications in which the formal classification is used, so we present evidence to acquaint biologists and managers with the rationale for the changes. The species name of the rainbow trout becomes mykiss, an older Latinized indigenous name of the Kamchatka trout. The generic designation of rainbow and cutthroat trout poses a more subjective problem, involving four possibilities: Salmo, Oncorhynchus, Rhabdofario, and Parasalmo. The balance of evidenc...

Evolutionary Relationships of the Plagopterins (Teleostei: Cyprinidae) from Cytochrome b Sequences

Abstract Sequences of cytochrome b (cytb) were used to examine composition and phylogenetic relationships of cyprinid fishes of the tribe Plagopterini, endemic to the Great Basin and Lower Colorado River in southwestern North America. The plagopterin genera, Lepidomeda, Meda, Plagopterus, and Snyderichthys, were most closely affiliated with the chubs Couesius and Margariscus of northern and eastern North America. As indicated by previous morphologic, allozymic, and mtDNA studies, Snyderichthys is intimately related to Lepidomeda. The relationship is paraphyletic, however, according to our molecular data. Snyderichthys from the Snake and Bear River drainages are part of a clade that includes Lepidomeda mollispinis and Lepidomeda albivallis according to the cytb sequence, with Snyderichthys from the central and southern Bonneville basin more divergent. This paraphyly and the complex geographic relationships of mtDNA sequences indicate a complex history of the group and cast doubt on the validity of morphologically diagnosed Snyderichthys. Estimates of divergence time, based on a combination of fossil and molecular data, indicate that the plagopterins are an ancient clade, at least 17 million years old.

REPRODUCTIVE ISOLATION AND INTROGRESSION BETWEEN NOTROPIS CORNUTUS AND NOTROPIS CHRYSOCEPHALUS (FAMILY CYPRINIDAE): COMPARISON OF MORPHOLOGY, ALLOZYMES, AND MITOCHONDRIAL DNA

Hybrid zones in fluvial fishes may be heterogeneous from drainage to drainage. The comparison of data from morphology, allozymes, and mitochondrial DNA (mtDNA) indicates variability in the causes and degree of restriction of gene flow between Notropis cornutus and Notropis chrysocephalus. Allozyme marker loci show frequency‐dependent introgression; i.e., the rarer species, whichever it is at a particular locality, tends to exhibit a higher proportion of introgressed alleles. Unlike allozymes, introgression of mtDNA haplotypes varies geographically. In westward‐flowing Michigan drainages, N. cornutus mtDNA haplotypes are more common in F1 hybrids and backcrosses, independent of parental frequencies. In eastward‐flowing Michigan drainages, N. chrysocephalus mtDNA is more common in F1 hybrids and backcrosses; this pattern may be due to local ecological effects or frequency‐dependent introgression. Morphological data alone are not sufficient to distinguish all classes of hybrids. The lack of concordance of morphological, allozymic, and mtDNA introgression patterns implies operation of one or two factors: 1) geographically variable patterns of selection against different hybrid and backcross combinations or 2) genetic differences between Michigan populations inhabiting eastward‐ and westward‐flowing drainage systems accumulated during historical isolation.

Zebra Mussel Predation by Round Gobies in the Laboratory

The round goby (Neogobius melanostomus), a native of the Black and Caspian seas, has spread from the original point of discovery in the St. Clair River to Lakes St. Clair, Erie, Huron, Michigan, and Superior. Round gobies utilize a broad range of foods, but prefer zebra mussels (Dreissena polymorpha). Gobies 6–10 cm in standard length consume mussels up to 7 × 13 mm. Zebra mussels 4–13 mm long are eaten at rates averaging between 36 and 47 per day, depending on predator/prey size; zebra mussels smaller than 4 mm were eaten at rates exceeding 100 per day. Feeding rates averaged 5.4/hr in 140-minute trials. Individual and clumped zebra mussels were preferred over sphaeriid clams on both sand and gravel substrates.

Sr isotopic composition of hydroxyapatite from recent and fossil salmon: the record of lifetime migration and diagenesis

By comparing the Sr isotopic composition of migratory fossil salmon, which lived in the ocean but died in continental regions, to the well established marine Sr isotopic record, the age of the continental deposit could be determined with high accuracy. This approach to marine-continental correlation and dating requires (1) that marine-resident salmon bear a marine S7Sr/86Sr value in their bones or teeth, and (2) that the original S7Sr/86Sr value of fossils is not overprinted by diagenesis. The vertebrae of modern, hatchery-reared salmon exhibit Sr isotopic variations indicative of freshwater to marine migration during bone growth. Modern marine S7Sr/S6Sr values were preserved in growth layers formed later in life. Marine-phase growth layers in the bones and teeth of the late Miocene migratory salmon, Oncorhynchus rastrosus, were subjected to stepwise selective leaching to separate biogenic hydroxyapatite from diagenetic calcium carbonate and recrystallized hydroxyapatite. Although the procedure yielded leachates with Sr/Ca and Ca/P values characteristic of apatite, the leachates had 87Sr/S6Sr values consistently less radiogenic than values for late Miocene seawater (~ 0.7087). The fossils were substantially contaminated by Sr from the hosting clastic sediments. Specimens in continental deposits differed in 87Sr/86Sr value from host sediments by 0.0002 to 0.0200, supporting the conclusion that these salmon were migrants from marine waters. However, because the original Sr isotopic composition of fossil bones and teeth cannot be determined with confidence, archaeological, paleobiological and stratigraphic applications of this technique may be limited.

FISH TAPHONOMY AND ENVIRONMENTAL INFERENCE IN PALEOLIMNOLOGY

Abstract The contribution of fish studies to palaeoecology generally takes the form of (1) inference from analogies in modern fish faunas and (2) fish taphonomy—the pattern of death and dispersal of bones. (1) Modern fish faunas and associated organisms provide taxonomic, ecological, or functional analogues for interpretation of ancient limiting factors and behaviors. These inferences presume taxonomic conservatism. They also presume functional relationships between morphological form and feeding mode or habitat. They become weak with increased geologic age or phyletic distance between ancient subject and modern anaogue. (2) Fish taphonomy may contribute information about limnology, community composition, life history, mortality, depositional environment, and preservation. Taphonomic reconstruction of ecology and preservation depends on the applicability of analogous processes in modern ecology and l limnology. In aquatic taphonomy, temperature is the most important factor in determining the fate of a carcass. Above about 16°C (depending on depth and pressure), most carcasses are made buoyant by bacterial decay gases and are transported to the surface where they may decay further and fall piecemeal into deepwater environments, or drift to beach environments where wave energy disarticulates, abrades, and scatters the bones. Below about 16°C, most carcasses remain on the bottom until buried; they may be disturbed by scavengers, depending on oxygen concentration in the hypolimnion.

Effects of industrial agriculture on climate change and the mitigation potential of small-scale agro-ecological farms

According to the Intergovernmental Panel on Climate Change (IPCC), agriculture is responsible for 10–12% of total global anthropogenic emissions and almost a quarter of the continuing increase of greenhouse gas (GHG) emissions. Not all forms of agriculture, however, have equivalent impacts on global warming. Industrial agriculture contributes significantly to global warming, representing a large majority of total agriculture-related GHG emissions. Alternatively, ecologically based methods for agricultural production, predominantly used on small-scale farms, are far less energy-consumptive and release fewer GHGs than industrial agricultural production. Besides generating fewer direct emissions, agro-ecological management techniques have the potential to sequester more GHGs than industrial agriculture. Here, we review the literature on the contributions of agriculture to climate change and show the extent of GHG contributions from the industrial agricultural system and the potential of agro-ecological smallholder agriculture to help reduce GHG emissions. These reductions are achieved in three broad areas when compared with the industrial agricultural system: (1) a decrease in materials used and fluxes involved in the release of GHGs based on agricultural crop management choices; (2) a decrease in fluxes involved in livestock production and pasture management; and (3) a reduction in the transportation of agricultural inputs, outputs and products through an increased emphasis on local food systems. Although there are a number of barriers and challenges towards adopting small-scale agroecological methods on the large scale, appropriate incentives can lead to incremental steps towards agro-ecological management that may be able to reduce and mitigate GHG emissions from the agricultural sector.

Phenetic and Cladistic Studies of Biochemical and Morphological Characteristics of Catostomus

Smith, G. R. (Museum of Zoology, Univ. of Michigan, Ann Arbor 48104) and R. K. Koehn (Dept. of Ecology and Evolution, State Univ. of New York, Stony Brook 11790) 1971. Phenetic and cladistic studies of biochemical and morphological characteristics of Catostomus. Syst. Zool., 20:282-297.-Sixteen of the nominal species in the genus Catostomus, predominantly in western North America, form a progressive morphological sequence in which adjacent forms are similar and perhaps not reproductively isolated. Several cladistic estimates indicate divergence in two primary lines or directions. The oldest cladistic furcation is phenetically trivial. Significant phenetic trends indicate evolution at several levels. The dominant trend involves osteological, oral, and hemoglobin characteristics leading to the mountain suckers. Secondary phenetic trends in body shape and in size of fins and scales have led to adaptations for life in large rivers in three separate lines. Two phenetic trends, involving meristic and serum protein characters, are involved in the adaptation of populations to local climatic conditions. [Catostomus; Cladistics; Phenetics; Biochemical taxonomy.] Fishes of the genus Catostomus (suckers -Catostomidae: Cypriniformes) inhabit streams and lakes of North America and Siberia. Approximately 20 nominal species live in western North America, north of northern Mexico. In addition, Catostomus commersoni is widespread in the Atlantic drainage of North America and Catostomus catostomus is distributed through northern North America and eastern Siberia. Two subgenera have been recognized (Smith, 1966). The subgenus Catostomus has been used to encompass an ecologically generalized and geographically widespread group of about 14 kinds with relatively unmo,dified jaws. This subgenus forms a progressive phenetic transition into the subgenus Pantosteus, which includes six usually montane western species with well-developed biting sheaths on the jaws (Figs. 1, 2). The kinds within each subgenus are usually distributed allopatrically, but populations of one group often live with representatives of the other subgenus. The result is that throughout much of the North American range of Catostomrus two, and occasionally three, phenetically divergent kinds may be found together. Most sympatric combinations are known to produce hybrids and cases of introgression are suspected (Hubbs et al., 1943; Hubbs and Hubbs, 1947; Smith, 1966; Koehn, 1967; Nelson, 1968). In almost no case does sympatly occur between phenetically most similar or cladistically most related species. The common hybridization between unlike forms, the lack of sympatry between similar forms, and the phenetic continuity through the genus (n.b.) suggest that the biological species concept, as usually defined (Mayr, 1963), may not strictly apply within the group, notwithstanding localized reproductive boundaries between divergent forms (Smith, 1966). The purpose of this paper is to present outlines of the phenetics of these fishes, to compare the phenetic patterns with estimates of cladistic affinities, and to compare patterns of correlation and distribution between several different kinds of characteristics-bio,chemical, osteological, and external morphometric and meristic.