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Ecology & molecular ecology Nitschke Rm 5013 Matthew Neilson, presiding.

9:00 AM


The Rainbow Darter Etheostoma caeruleum is a small benthic fish common in the eastern United States in stream riffles, whose population genetic structure in the Great Lakes region is largely unknown. The Ohio Environmental Protection Agency's (OEPA) Index of Biotic Integrity uses this species as an indicator for good water quality. Mitochondrial DNA sequences were analyzed from the cytochrome b gene and control region, along with nuclear microsatellite data, to compare the population structure and genetic variation of the rainbow darter within and outside of the Lake Erie watershed, including the Big Darby Creek, the Blanchard, Chagrin, Cuyahoga, Grand, and Little Miami Rivers, Ohio. Nucleotide sequences of the cytochrome b gene (1122 bp) revealed 34 different haplotypes. Two distinct and divergent population groups were recovered based on Bayesian Structure analysis and a [O.sub.ST] = 0.383, one in the Lake Erie watershed (Blanchard, Chagrin, Cuyahoga, and Grand Rivers) and the other in the Ohio River system (Big Darby Creek and the Little Miami River), which did not share haplotypes. The two groups are genetically separated by a p-distance of 0.011, diverging ~550,000 years ago during the mid-Pleistocene Epoch according to our molecular clock calibration for darters.


DNA sequencing has led to the resolution of many cryptic taxa, which are especially prevalent in the North American darter fishes (Family Percidae). The Greenside Darter, Etheostoma blennioides, commonly occurs in the lower Great Lakes region, where two putative subspecies, the eastern "Allegheny" type E. b. blennioides and the western "Prairie" type E. b. pholidotum, overlap. The objective of this study was to test the systematic identity and genetic divergence distinguishing the two subspecies in areas of sympatry and allopatry in comparison to other subspecies and close relatives. DNA sequences from the mtDNA cytochrome b gene and control region and the nuclear S7 intron 1 comprising a total of 1,497 bp were compared from 294 individuals across 18 locations, including the Lake Erie basin and the Allegheny, Meramec, Ohio, Susquehanna, and Wabash River systems. Results showed pronounced divergences ([e.sub.ST] = 0.92 - 0.97; p-distance = 0.025-0.039) among taxa presently designated as E. b. blennioides, E. b. newmanii, and E. b. pholidotum, as well as identification of a fourth clade in the Meramec River. Most traditional morphological characters were statistically significant (P< 0.0001) in distinguishing between populations of E. b. blennioides and E. b. pholidotum, including scale counts and degree of ventral squamation using a multivariate analysis of variance and chi-square tests; bur overlapped, precluding accurate identification of individuals. The four significantly divergent taxa of the Greenside Darter complex should be further evaluated for potential elevation to species status.


The Eurasian round goby Apollonia melanostoma (formerly known as Neogobius melanostomus) invaded the North American Great Lakes in 1990 via ballast water, where it quickly spread and has become one of the most abundant benthic fishes in the lower lakes. The round goby found a ready-made food source in the also-invasive dreissenid mussel population, and is prey to game fishes and preys upon their eggs and young. The objective of the present study was to elucidate the likely source population(s) for the North American introduction(s) and to evaluate spread patterns using a dual genome population genetic approach. We sequenced the mitochondrial DNA cytochrome b gene and analyzed seven nuclear microsatellite loci to test the genetic relationships of 1158 individuals from 25 North American and 22 Eurasian population sites. Results showed two subspecies in Eurasia--A. m. melanostoma centered in the Black Sea and A. m. affinis in the Caspian Sea drainage. Both lineages recently expanded into other parts of Eurasia, and only the Black Sea lineage colonized North America. High genetic diversity characterizes North American and Eurasian populations, supporting very large North American introductions originating from a large number of founding propagules. Allelic differences separate Great Lakes locations, indicating multiple introduction sources and significant population structure. Bayesian assignment tests, three-dimensional factorial component analysis, analysis of molecular variance, and contingency tests of genetic differentiation significantly link the central Great Lakes region with genotypes from the port of Kherson, Ukraine near the mouth of the Dnieper River in the north central Black Sea (p> 0.75). Other Great Lakes sites reveal different linkages. Genotypes that are common in the Great Lakes are also common in saline waters of the Black Sea, suggesting that the round goby likely will be successful in spreading throughout North American coastal estuaries--given transport and the opportunity.


TEMPORAL AND SPATIAL POPULATION GENETIC STRUCTURE OF THE EURASIAN ROUND GOBY: INVASION PATTERNS IN THE GREAT LAKES. Emily A. Sopkovich, Joshua Brown ( & Carol A. Stepien ( Lake Erie Center and Dept of Environmental Sciences, University of Toledo, 6200 Bayshore Rd, Toledo OH 43618

The Ponto-Caspian round goby Apollonia melanostoma (formerly Neogobius melanostomus) invaded the Lake St. Clair region in 1990 via ballast water. It quickly spread throughout the Great Lakes and is now one of the most abundant benthic fishes in the lower Great Lakes. The objective of this study is to test whether the genetic composition of the exotic population has remained the same from place to place and over the time course of the invasion. We sequenced the mitochondrial cytochrome b gene and analyzed eight newly-developed nuclear microsatellite loci to test for spatial and temporal patterns. We tested 397 individuals from 2-3 time periods (ranging from 1993 to 2007) at five locations in Lakes St. Clair, Erie, and Michigan. Results using the cytochrome b gene showed negligable temporal genetic change within round goby population sites and some spatial divergences among different locations (FST= 0.000 - 0.172). Microsatellite analyses revealed significant temporal genetic change in round goby samples from Lake Michigan between 1998 to 2007 (FST= 0.106). Samples from Lake St. Clair and the St. Clair River, the original introduction point, were each temporally consistent in genetic composition (FST=0.009; 0.017, respectively), whereas those from Lake Erie changed (FST= 0.021 - 0.048). Therefore, peripheral population sites appear to have changed over the time span of the invasion, whereas central sites remained more genetically stable. In addition, there is spatial genetic structure among the different locations, likely reflecting differential introduction histories. Genetic information thus aids our understanding of the ecological adaptations underlying the round goby's invasion success.

10:00 AM

A TEMPORAL ANALYSIS OF WALLEYE GENETIC STOCK STRUCTURE IN LAKE ERIE. Jo A. Banda, Carol A. Stepien, Great Lakes Genetics Laboratory, Lake Erie Center, University of Toledo, Toledo OH 43606

Walleye, Sander vitreus, is one of the most important exploited fish species in the lower Great Lakes, whose genetic stock structure is of importance to fishery management. Research using nuclear DNA microsatellite loci and mtDNA sequences have shown that many spawning groups of walleye in Lake Erie genetically differ due to spawning site philopatry by both males and females. This study is the first to test whether these walleye spawning population groups are temporally stable. We used variation at 10 nuclear microsatellite loci to compare the genetic composition of walleye spawning in the Maumee River (the largest Lake Erie spawning group) across 12 years; 1995 (N=50), 1998 (N=28), 2003 (N=76), and 2006 (N=51), and made statistical comparisons with our 2003 database from the 10 major Lake Erie spawning sites (N=410). Results showed no temporal differences among walleye spawning in the Maumee River in three of the four sampling years (FST = 0.001-0.005), indicating a common gene pool for all except the 2003 samples. The genetic composition of the 2003 walleye run in the Maumee River significantly differed from the other years (FST= 0.045-0.056), exhibiting more gene flow with other southern Lake Erie shore spawning groups (FST= 0.001-0.002). This 2003 run constituted the largest walleye recruitment year in Lake Erie for two decades, and greater gene flow may have enhanced recruitment, which merits further study. Our investigation illustrates the importance of testing temporal patterns of genetic variation (rather than a single year "snapshot') to understand stock structure.

10:15 AM A LANDSCAPE GENETIC ANALYSIS OF GREAT LAKES YELLOW PERCH POPULATIONS IN RELATION TO THEIR VARIATION ACROSS NORTH AMERICA. Osvaldo J. Sepulveda Villet and Carol A. Stepien Lake Erie Center, University of Toledo. 6200 Bayshore Rd. Toledo, OH, 43618.

The Yellow Perch, Perca flavescens, is a key North American sport and commercial fish whose abundances and distribution center in the lower Great Lakes. Its populations have fluctuated historically due to unstable recruitment patterns and exploitation. Our study analyzes population genetic structure across its native range, using a landscape genetics approach and provides an important management tool and interpretation of its phylogeographic and recent history. Eleven microsatellite loci and mitochondrial DNA control region sequences are analyzed for over 700 spawning individuals from Lakes Superior, Michigan, Huron, Erie, and Ontario with outlying populations from Lake Winnipeg, Lake Champlain, the upper Mississippi River Basin, and the Atlantic and Gulf coastal regions. Analyses include phylogenetic trees, pairwise divergence comparisons, AMOVA partitioning, Mantel regression, Bayesian assignment, and Monmonier geographic networks. Appreciable fine-scale genetic structure in Lake Erie is described (est = 0.179, P = 0.03), ranging to pronounced broad-scale divergence Great Lakes versus Atlantic coastal populations (est = 0.418, P < 0.0001). This Atlantic coastal group did not contribute to the Post-Pleistocene founding of modern Great Lakes populations. Patterns in the Great Lakes suggest contributions from at least two primary glacial refugium groups. The Lakes house genetically separable population groups, with further population division in most. Yellow Perch spawning in eastern Lake Frie appear more closely allied to groups in Lake Ontario than to those in western Lake Frie.

10:30 AM

QUANTIFYING MICROCYSTIS SP. IN WESTERN LAKE ERIE AND MAUMEE BAY USING DENSITY SEPARATION AND MICROSCOPY, 2002-2006. Jesse E. Filbrun Biology Dept. Bowling Green State University, Justin D. Chaffin jchaffi2@UTNet.UToledo.Edu Dept. of Environmental Sciences / Lake Erie Center University of Toledo, Thomas B. Bridgeman TBridge@UTNet.UToledo.Edu Dept. of Environmental Sciences / Lake Erie Center University of Toledo, 469 S. Summit St. #77 Bowling Green OH 43402

Growth of the toxic cyanobacteria, Microcystis sp., has increased in recent years in Maumee Bay and western Lake Frie resulting in harmful algal blooms (HABs) during summer months. To investigate environmental causes of HABs, it is important to quantify differences in algal abundance between months and years. However, because cell counts of Microcystis are time-consuming, it is difficult to processes sufficient samples to adequately characterize multiple blooms. We developed a density separation technique that permitted relatively rapid quantification of Microcystis volume in archived zooplankton tows from western Lake Frie. We report the results of sample analysis for 2002-2006. Microcystis volume in samples collected approximately biweekly at six sites (N = 145) was determined in calibrated Imhoff cones and some samples (N= 60) were further processed to determine Microcystis cell density. Total cells in the sample and cell density in the lake water increased linearly with volume of Microcystis in samples ([r.sup.2] = 0.84 and 0.89), indicating that volume estimates can be used as a surrogate for cell counts. Averaging Microcystis cell density on a monthly basis for all sites allowed for temporal representation of bloom intensity, whereas monthly density by site allowed for a spatial illustration of the blooms. From heaviest to lightest Microcystis blooms (average monthly Microcystis volume x [m.sup.-2] summed over July, August, September), the years are ranked as follows: 2003 (355.2 ml x [m.sup.-2]), 2004 (311.4 ml x [m.sup.-2]), 2006(233.5 ml.[m.sup.-2]), 2005 (120.8 ml x [m.sup.-2]), 2002 (54.5 ml x [m.sup.-2]).

10:45 AM

WHAT'S IN A NAME? NEW IDENTITY OF INVASIVE GOBIES IN THE GREAT LAKES. Matthew E. Neilson ( and Carol A. Stepien (; Lake Erie Center and Department of Environmental Sciences, University of Toledo; 6200 Bayshore Rd, Oregon OH 43618

Exotic species often belong to poorly-understood groups whose true phylogenetic relationships are unknown. In areas prone to species invasion, such as the Great Lakes, this taxonomic confusion often obfuscates correct ecological comparisons, and thus renders conservation and management policies potentially invalid. The round (Neogobius melanostomus) and tubenose (Proterorhinus marmoratus) gobies--along with other members of the PontoCaspian neogobiin gobies--have undergone recent Eurasian range expansion, as well as establishing invasive populations in Great Lakes waterways. We sequenced mitochondrial and nuclear DNA from native and invasive populations of 14 neogobiin goby species to determine their evolutionary history. The lineage containing the round goby and its sister species was separate from that containing the remainder of the genus Neogobius (100% bootstrap support for both lineages), showing that the round goby belongs in a separate genus. The subgeneric name for the round goby (plus sister species) thus is elevated to generic status, making the new name of the round goby Apollonia melanostoma. We found genetic distance of 0.166 between freshwater and marine lineages of tubenose gobies, indicating species level separation. There are two separate species of tubenose goby--the original P. marmoratus in marine and estuarine habitats and the "new" freshwater species in Eurasian rivers and the Great Lakes. The freshwater tubenose goby was originally described as P. semilunaris Heckel 1837 (prior to its synonymy with P. marmoratus), and the name is resurrected for this taxon. This study highlights the use of genetic tools in understanding and describing cryptic taxonomic diversity in invaded ecosystems.
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Publication:The Ohio Journal of Science
Geographic Code:1U3OH
Date:Mar 1, 2008
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