AR-1562
THE SOUTHWESTERN NATURALIST 52(3):424-445 SEPTEMBER 2007
NOTES
CORBICULA FLUMINEA (BIVALVIA: SPHAERIACEA: CORBICULIDAE) IN COLORADO
JAMES R. CORDEIRO,* ARLENE P. OLIVERO, AND JOHN SOVELL
NatureServe, 11 Avenue de Lafayette, 5th Floor, Boston, MA 02111 and Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (JRC) The Nature Conservancy, Eastern Resource Office, 11 Avenue de Lafayette, 5th Floor, Boston, MA 02111 (APP) Colorado Natural Heritage Program, Colorado State University, 254 General Services Building, Fort Collins, CO 80523 *Correspondent: jay- cordeiro@ natureserve. org
ABSTRACT-We documented range expansion of the Asiatic clam, Corbiculafluminea, in Colorado since its first occurrence in 1993 in the South Platte River drainage. Using recent surveys and literature records, we compiled known occurrences of the Asiatic clam over the past 12 y and determined that it has expanded beyond the initial confines of the Platte River and Arkansas River drainages into the Colorado River and San Juan River drainages. All previously reported occurrences are still extant and the species continues to spread to new localities, especially in the Arkansas River drainage. We speculate on potential negative impacts to native freshwater mussels in Colorado, but have not conducted any definitive studies.
RESUMEN-Deseamos documentar la extensi6n de la gama de la almeja Asiatica, Corbiculafluminea, en Colorado desde el primera ocurrencia en 1993 en el drenaje del Rio South Platte. Usando examenes y expedientes recientes de la literatura, compilamos ocurrencias sabidas de la almeja Asiatica a partir de los docena anios pasados y determinada que las poblaciones se han ampliado maLs all;a de los limites iniciales de los drenajes del Rio Platte y del Rio Arkansas en los drenajes del Rio Colorado y del Rio San Juan. Todas las poblaciones previamente divulgadas siguen siendo extant y muchas continfian a aumento a nuevos lugares, especialmente en el drenaje del Rio Arkansas.
Studies of freshwater mollusks in the Rocky been documented in 42 states (Counts, 1986; A. Mountain region are rare compared to other M. Foster et al., http://nas.er.usgs.gov/queries/ regions of the United States, such as the Southeast SpFactSheet.asp?speciesID=92; A. J. Benson et and Northeast. Surveys include those by Cockerell al., 2004, unpublished report, United States Fish (1889, 1927), Ellis (1916), Ellis and Keim (1918), and Wildlife Service, Arlington, Virginiana). The and Henderson (1907a, 1907b, 1912,1924). More first documented occurrence in Colorado was in recent surveys include Brandauer and Wu (1978), June 1993 in Cherry Creek Reservoir, Arapahoe Herrmann and Fajt (1985), Wu (1989), Liu et County al. (Nelson and McNabb, 1994). Subsequent (1996a, 1996b), Cordeiro (1999), Cordeiro andoccurrences in the state also have been docu MacWilliams (1999) and A. H. Clarke et al. (2003, mented in Highline Lake, Mesa County, in 1995 unpublished report). The invasive Asiatic clam, (Kreiser and Mitton, 1995). It has become Corbiculafluminea (Miller, 1774) (family Corbicu established in Queen's (=Nee Skah) Reservoir, lidae), is native to temperate and tropical Kiowa County; in pools of the Arkansas River southern Asia west to the far eastern Mediterra below the dam to John Martin Reservoir, Bent nean, as well as northern Africa, the southeastern County; and in Pueblo Reservoir, Pueblo County Asian islands, and eastern Australia (Morton, (Cordeiro, 1999; Cordeiro and MacWilliams, 1986). It was first reported in the United States 1999). in 1938 in the Columbia River in Pacific County, Based on targeted surveys of freshwater mol Washington (Burch, 1944). Since that time it has lusks across Colorado in 2001-2004, we here
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms September 2007 Notes 425
report new occurrences Heritage Program of Corbicula of Totten fluminea Lake in 2004, 5 y from 18 additional after sites, the 6initial well away discovery, from those revealed that the previous reported species (Table also is1). extant Unlike at Cordeirothis site. In particular, (1999), who comprehensively the occurrence surveyed of 12 additional115 sites sites on the (80 different Arkansaswater bodies) River across drainage the indicate eastern C. fluminea is half of the state expanding for freshwater in this region.bivalves, occur rences reported Corbicula here are fluminea the result has beenof both documented in 4 a comprehensive of survey6 major of drainage 350 sites basins in eastern (Arkansas, Colorado, Colorado in 2001-2002 Platte, San(A. H.Juan; Clarke not etdocumented al., 2003, in Rio Grande unpublished report, or White-Yampa) Colorado Division in Colorado of Wild (or 5 of the 12 life) and 453 sites subbasins) in western as of Colorado 2004 (Fig. in 1).2003 Historical intro 2004 (J. R. Sovell ductions et inal., North 2005, America unpublished can be initially traced report, Colorado to Division passive dispersalof Wildlife) on waterspecifically currents, anthropo targeting freshwater genic transport mollusks inacross boat theballast state. and bait buckets, Also included are or periodicthrough non-targeted the aquarium surveys pet trade (Counts, at various new 1986; sites Isom, in eastern 1986). Range Colorado expansion as of occur documented by rences the Colorado on the NaturalArkansas Heritage River drainage has Program. Copies occurred of these rapidly reports since initialcan be discovery of C. obtained by contacting fluminea co-author there in 1996J. R. (Cordeiro, Sovell at 1999; Cordeiro the Colorado Naturaland MacWilliams, Heritage Program1999) with . 12For additional sites purposes of this discovered. project, A easternsimilar rapidColorado invasion is pattern from defined as all recentareas east initial of introductionsthe Continental also has been docu Divide and western mented Colorado in Texas includeswhere the all species areas occurs in 180 west of the Continentalof 257 counties Divide (Karatayev plus areas et al., 1995). New >200 m elevation invasions east of arethe notContinental limited to Divide. the eastern plains as Also included are new periodic occurrences non-targeted have been surveys uncovered in differ at various new ent sites regions in eastern of the ColoradoColorado River as drainage as documented by well. the The Colorado widely Natural disjunct Heritage distribution in Colora Program. In June do of 1999, the S.-K.remaining Wu collected occurrences 15 supports specimens from a theory Bonny of human-influencedReservoir in Yuma transport. At least County close 2to instances Kansas. ofA secondaquarium site dealers was in Colorado discovered in Septemberselling the of species the same have year been in documented Totten Lake in(Cordeiro Montezuma and MacWilliams, County in 1999; the University of extreme southwestern Colorado corner Museum of thespecimen state (Col lot UCM 41599). orado Natural Heritage Although Program previously , pers. reported comm.). to be limited in In 2001-2002, dispersal12 additional capability sites by were intolerance discov of cold temper ered, all in the atureArkansas (Mattice River and drainage: Dye, 1976; 3 in Graney the et al., 1980; Purgatoire River; McMahon, 3 in John 1983; Martin Sickel, Reservoir; 1986; French 2 and Schloes new sites in the ser, Arkansas 1991, 1996), River C. (1.2fluminea km north has been shown to and 6 km west survive of Lamar); cold temperatures and 1 each in (<40C) Hasty in areas without Lake, Lake Meredith thermal (=Meredithrefuge (Kreiser Reservoir), and Mitton, 1995; Cor Nee Gronda Reservoir, deiro and and MacWilliams, Nee Noshe Reservoir 1999). Totten Lake is (A. H. Clarke etsituated al., 2003, at aboutunpublished 2,050 mreport; elevation, Queen's, Fig. 1). Surveys Nee of Gronda western and Colorado Nee Noshe in 2003Reservoirs at about 2004 uncovered 1,700 4 additional m, Cherry sites Creek in the Reservoir Colora at about 1,850 m, do River drainage: Pueblo Beaver Reservoir Pond at aboutin Delta 1,600 Co., m, Highline Lake House Creek in at Montezuma about 1,550 m,Co., Lake and Meredith Spring and at about 1,350 m, Whitewater creeks John in MartinMesa Co. Reservoir (J. R. Sovell at about et al., 1,280 m, Hasty 2005, unpublished Lake report).at about 1,200In addition, m, and occurBonny Reservoir at rences in Bonny about Reservoir, 1,200 m Cherry elevation Creek (http://parks.state.co.us/ Reser voir, and the Arkansas Boating/BoatableWaters/). River (belowJohn NewMartin localities in west Reservoir) have ern been Colorado confirmed range fromto be aboutextant. 1,550 to 3,200 m Additional surveys elevation by the(Beaver Colorado Pond Naturalabout 3,200 m, House
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms 426 The Soutthwestern, Naturalist Vol. 52, no. 3
3~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~n0-~b 0- - -0 o -~~~.. n-I-.D iZ-.. -"Z~~~~ )- G'4.. Lo- '~~~~t4.0 - r-~-~ . e. "4-0-.a r-- C ~C.. C - 00C an"I U.) O.'..J~ 0 C,c .. t l- 0IC F .4
Cld Cld ct ~~~~Cad Ca CZ CZ Cad C Cad at C ~~~~, ~~~~~~~~, Ca Ca ~~~~~~~~~~~~~~~~~~~~~~~~~0 C0A A r U) Cl m Cl 3 3 IC C)d et Cd C)d C)d C) CZ CZ m 1~ -~ - 4 -~
UC ~~~~~~ ~~~ 0 C~~~~~~ 0 ~~~0. 0 a0-CI UC4 CL4 U)4 U)4 U) U)4 0 U) U U) a .. ~ : C U a - U) U:) U:) U:) U C ) U
Cad
3 UC U) 0 3~~~~~~~m mU) rA r Cad m 1 Ca -4~ Ca4 Ca
0 Cld Cld Cld3 ClC)C)3 00 C) ) -C) C
C) C) 3 *~~~~~~~~~~~~~~~~~~~~ *.4 C) l
64 U~~~~~~~~~~~~~~~~~C UC U C, (4-4 C4- 4~~Ca-J Ca 3l CaC 3C dC -b Ca 0/ Ca r C) 3
0 5 Ca ~~~~~~~~~~~~~~~~~~~~~~~- .(3 ) 0 C) C-~~~~~~~~~~~~~~~~ U) ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 34- - Q 3 0C, 0 Cad It -e 0 00~~~~~~~~~~~nC' U 4~~~~~~~~~~~~~~~~~~~~~ .c o *3 C: 3 ~~~~~~~~~~~~~~bi - 0 Ca 0 Ca1
Q C) ~~~ S~~~~~Ca CU 3l- t 0S d-(U00 0 5 00 Ca~ ~~~ ~~~ Ca Ca U 0 bi U 0 4-4 cli0 ~ ~ C) Ca~ 0' 4-4 n0 Cld Cld C) c0- 3 - .0 C)3C S C-~~~~~ -3 ~~~~~~CaCa ~~~~~~~ ~- Ca U 5z 3~ -3~ ~ U~ 3~ .5-CCa, ~~ 0It &n .-r)0 C/)C 00 -3 C0 0 0 CO 0 O-CC:~~~~~~~~~~~~~~S Ca C) C) C) ~ ~4- C.~~~~ -l C)d 0 LZ 0. 0 0 6 00 Z4 00 00 a
0 *~~~~~~~~~4J 4- - * 0 0 Cl
~~~~20 0~~~~~~0 0 )
.5CO) U) (A C. C) *- 4 U) U) 0 CL) C > C00 ) --3 U 4-J 0 .r 0 C) Ca ) 3 U)e Cld CA m 0Cld 64C 0 U)C)6: C ))0U )) C)dU C) C C 0 .5 ~~ ~U) ~ UU) Ca U)C) QC.) Ca Caz Ca~ 3C)~64 C) >m 004 - C's Cld~ ~ ~ ~ ~~~~~C C)O3 3 U U~~U 0 - 0 -0 C 0d H z n~
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms September 2007 Notes 427
Creek about 2,450 m, Spring Creek about 1,850 m, Whitewater Creek about 1,550 m-J. R. Sovell et al., 2005, unpublished report). All experience periods "0 0 t-a ,o of freezing during winter with potentially no areas of thermal refuge. Morgan et al. (2003) detected positive correlation of survival in winter with in 01, ~ ~ average water temperature in winter and negative 0 . 0 0 U) 0 n0 C40 0 C 0 0 correlation with frequency of daily mean water t- ) -cXc)o~ t- o c temperatures '1?C in a C. fluminea in the lower Connecticut River. Despite high mortality in winter from cold water temperatures and in early spring "0 from high water flow, Morgan et al. (2003) noted that clams were over-wintering under ambient river temperatures and surviving in the lower Connecti cut River for -10 y. Other drainages in Connecti o a a~~~~~r cut also now support over-wintering populations, as well (J. R. Cordeiro, pers. observ.). Corbicula fluminea apparently also is over-wintering success 0 0 0~~0 C l C d fully throughout Colorado, although we have not 0 documented relative abundance or winter mortal ity rates. The impact of the spread of Asiatic clams in Colorado on native freshwater mussels is not )~~~ C ~ C known, although preliminary studies indicate the
bO species competes for space and food (Fuller and Imlay, 1976; Clarke, 1986; Devick, 1991; Bogan, 1993; Strayer, 1999). Filter-feeding activity of C. 0 0 - fluminea causes significant decline in phytoplank "0 ton levels (Cohen et al., 1984; Leff et al., 1990), which in turn, may lead to a trickle-down effect bl 0 in other filter-feeding organisms, including freshwater mussels. Cooper et al. (2005a, 0 0 0 2005b) linked potential negative effects of C. C 0~~ " C S CZ ftuminea die-offs on native freshwater mussels due to increase in ammonia levels. Bio-fouling C' ZZ" impacts of C. fluminea, particularly on power ie) Q plants, industrial water systems, and irrigation canals and pipes, have been well documented (Prokopovich and Hebert, 1965; Isom, 1986; 0 C Isom et al., 1986; Williams and McMahon, 1986; C) ~ ~ ~ J Devick, 1991; Morgan et al., 2003, 2004). Only 3 native species of freshwater mussels are consid ered extant in Colorado and of these, Pyganodon grandis (Say, 1829) and Uniomerus tetralasmus (Say, 1831) co-occur with C. fluminea (Cordeiro, bC u V 1999; A. H. Clarke et al., 2003, unpublished report). P. grandis is considered imperiled (rank S2- Imperiled because of rarity or because of some factor(s) making it vulnerable to extirpa tion or extinction) and U. tetralasmus is consid ered critically imperiled (rank S1- Critically Imperiled because of extreme rarity or because of some factor(s) making it especially vulnerable
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms 428 The Southwestemn Naturalist vol. 52, no. 3
\NQ HPLArTTd t:X/~/ WHITE-YAMPA'/
CPOLORADO OWTER
GUNNISONf UPPE 'AR Nsa s
I>RIO GRANDE k COLORA~~~Jo ~ HEAD WA TERS bOLORES"11 SAN JUAN -CIMRRO
&'. 25 SObliles --
FIG. 1 -Distribution map of Corbiculafluminea (Mutller) in Colorado (see Table 1 for specific locality information).
to extirpation or extinction) competitive in Colorado interaction (Nature between the 2 species at Serve, http://www.natureserve.org/explorer). the remaining sites have P. not been investigated. grandis has 26 water bodies documented with extant occurrences in the Thanks state to(Cordeiro, G. Hall (University 1999; of Colorado Museum) A. H. Clarke et al., 2003, for unpublished a loan of UCM report). specimens. It co-occurs with C. fluminea in Cherry Creek Reservoir (site F), Hasty Lake Literature (site G), JohnCited Martin Reservoir (sites J, K, L), and Pueblo Reservoir (site P; Table Bogan,1). U. tetralasmus A. E. 1993. Freshwatermay be bivalve extinctions extirpated from Colorado (Mollusca: with the Unionoida): only recent a search for causes. Amer specimens being a single ican Zoologist adult dead 33:599-609. shell collected by the first author Brandauer, on the N., southwestern and S.-K. Wu. 1978. The Bivalvia of shoreline of Queen's Reservoir Colorado. in PartKiowa 2. TheCounty freshwater mussels. Natural (site T) in 1999 (Cordeiro, History 1999) andInventory another of dryColorado 2:41-60. shell collected in the Arkansas Burch, RiverJ. Q. just1944. north Checklist of of West American Lamar in Prowers County mollusks. (site A) Minutesin 2001 (A.of theH. Conchological Club of Southern California 38:18. Clarke et al., 2003, unpublished report), co Clarke, A. H. 1986. Competitive exclusion of Canthyria occuring in both sites with C. fluminea (Cordeiro (Unionidae) by Corbicula fluminea (M?ller). Mala and MacWilliams, 1999). Historical occurrences cology Data Net 1:3-10. of U. tetralasmus from the Cimarron River, Carrizo Cockerell, T. D. A. 1889. Preliminary remarks on the Creek, and Lake Henry molluscanare believed fauna extirpated of Colorado. Journal of Conchol (Cordeiro, 1999) and potential ogy 6:60-65. negative effects of
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms September 2007 Notes 429
Cockerell, T. Henderson,D. J.A. 1907?>. The1927. Mollusca of Colorado. PartZoology II. of Colorado. University of Colorado, University of Colorado Studies Boulder. 4(3):167-185. Cohen, R. R. H., Henderson,P. V. J. 1912. Dresler,The Mollusca of Colorado. Part E. III. J. P. Philips, and R. L. Cory. 1984. The effectUniversity of Colorado of Studies 9(2/3):53-64.the Asiatic clam, Corbicula fluminea, on phytoplankton Henderson, J. 1924. Mollusca of Colorado, Utah,of the Potomac River, Maryland. Limnology Montana, Idaho, and Wyoming. and University Oceanographyof 29: 170-180. Colorado Studies 13:65-223. Cooper, N. L., J. R. Bidwell, and D. S. Cherry. 2005a. Herrmann, S. J., and J. E. Fajt. 1985. Additional Potential effects of Asian clam {Corbicula fluminea) Colorado records for Anodonta grandis grandis Say die-offs on native freshwater mussels (Unionidae) I: (Bivalvia: Unionidae). Nautilus 99:107-109. water-column ammonia levels and ammonia toxic Isom, B. G. 1986. Historical review of Asiatic clam ity. Journal of the North American Benthological ( Corbicula) invasion and biofouling of waters and Society 24:369-380. industries in the Americas. American Malacological Cooper, N. L., J. R. Bidwell, and D. S. Cherry. 2005b. Bulletin, Special Edition 2:1-5. Potential effects of Asian clam ( Corbicula fluminea) Isom, B. G., C. F. Bowman, J. T. Johnson, and E. B. die-offs on native freshwater mussels (Unionidae) Rodgers. 1986. Controlling Corbicula (Asiatic clams) II: porewater ammonia. Journal of the North on complex power plant and industrial water American Benthological Society 24:381-394. systems. American Malacological Bulletin, Special Cordeiro, J. R. 1999. Distribution and habitat of Edition 2:95-98. freshwater mussels (Bivalvia: Unionoida: Union Karatayev, A, R. G. Howells, L. E. Burlakova, and B. D. idae) in Colorado. Natural History Inventory of Sewell. 1995. History of spread and current Colorado 19:1-56. distribution of Corbicula fluminea (M?ller) in Texas. Cordeiro, J. R., and S. MacWilliams. 1999. Occurrence Journal of Shellfish Research 24:553-559. of the Asian clam, Corbicula fluminea (M?ller, 1774) Kreiser, B. R., and J. B. Mitton. 1995. The evolution of (Bivalvia; Sphaeriacea; Corbiculidae) in Colorado. cold tolerance in Corbicula fluminea (Bivalvia: Veliger 42:278-288. Corbiculidae). Nautilus 109:111-112. Counts, C. L. Ill 1986. The zoogeography and history Leff, L. G., J. L. Burch, and J. V. McArthur. 1990. of the invasion of the United States by Corbicula Spatial distribution, seston removal, and potential fluminea (Bivalvia: Corbiculidae). American Malaco competitive interactions of the bivalves Corbicula logical Bulletin, Special Edition 2:7-39. fluminea and Elliptio complanata in a coastal plain Ellis, M. M. 1916. Anodonta danielsi Lea in Colorado. stream. Freshwater Biology 24:409-416. Nautilus 29:116-119. Liu, H.-P., J. B. Mitton, and S. J. Herrmann. 1996a. Ellis, M. M., and M. Keim. 1918. Notes on the glochidia Genetic differentiation in and management recom of Strophitus edentulus pavonius (Lea) from Colora mendations for the freshwater mussel, Pyganodon do. Nautilus 32:17-18. grandis (Say, 1829). American Malacological Bulle French, J. R. P., Ill, and D. W. Schloesser. 1991. Growth tin 13:117-124. and overwinter survival of the Asian clam, Corbicula Liu, H.-P., J. B. Mitton, and S.-K Wu. 19966. Paternal fluminea, in the St. Clair River, Michigan. Hydro mitochondrial DNA differentiation far exceeds biologia 219:165-170. maternal mitochondrial DNA and allozyme differ French, J. R. P., Ill, and D. W. Schloesser. 1996. entiation in the freshwater mussel, Anodonta grandis Distribution and winter survival health of Asian grandis. Evolution 50:952-957. clams, Corbicula fluminea, in the St. Clair River, Mattice, J. S., and L. L. Dye. 1976. Thermal tolerance of Michigan. Journal of Freshwater Ecology 11: the adult Asian clam. In: G. W. Esch and R. W. 183-192. McFarlane, editors. Thermal ecology. Vol. 2. Unit Fuller, S. L. H., and M. J. Imlay. 1976. Spatial ed States Energy and Development Administration competition between Corbicula manilensis (Philippi), Symposium, Washington, D.C. Pages 130-135. the Chinese clam (Corbiculidae), and fresh-water McMahon, R. F. 1983. Ecology of an invasive pest mussels (Unionidae) in the Waccamaw River Basin bivalve, Corbicula. In: W. D. Russell-Hunter, editor. of the Carolinas (Mollusca: Bivalvia). Association of The Mollusca. Volume 6. Ecology. Academic Press, Southeastern Biologists Bulletin 23(2):60. London, United Kingdom. Pages 505-561. Graney, R. L., D. S. Cherry, J. H. Rodgers, Jr., and J. Morgan, D. E., M. Keser, J. T. Swenarton, and J. F. Cairns, Jr. 1980. The influence of thermal dis Foertch. 2003. Dynamics of the Asiatic clam charges and substrate composition on the structure Corbicula fluminea (M?ller) in the lower Connecticut and distribution of the Asian clam, Corbicula River: establishing a foothold in New England. fluminea, in the New River, Virginia. Nautilus Journal of Shellfish Research 22:193-203. 94:130-135. Morgan, D. E., M. Keser, J. T. Swenarton, and J. F. Henderson, J. 1907a. The Mollusca of Colorado. Part I. Foertch. 2004. Effect of Connecticut Yankee Power University of Colorado Studies 4(2):77-96. Plant on dynamics of Asiatic clams and their
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms 430 The Southwestern Naturalist vol. 52, no. 3
interactions with native bivalves.Strayer, American D. L. 1999. Fisheries Effects of alien species on Society Monograph 9:419-439. freshwater mollusks in North America. Journal of Morton, B. 1986. Corbicula the in Asia-anNorth updated American synthe Benthological Society sis. American Malacological 18:74-98. Bulletin, Special Edi tion 2:113-124. Williams, C. J., and R. F. McMahon. 1986. Power station Nelson, S. M., and C. McNabb. entrainment of Corbicula1994. fluminea New (M?ller) inrecord re of Asian clam in Colorado. lation Journal to dynamics, reproductive of cycleFreshwater and biotic Ecology 9:79 Pages. and abiotic variables. American Malacological Bul Prokopovich, N. P., and D. letin, J. Special Hebert. Edition 2:99-111. 1965. Sedimen tation in the Delta-Merdota Wu, S.-K. 1989. Canal.Colorado freshwater Journal mollusks. Natural of the American Water Works Association 57:375-385. History Inventory of Colorado 11:1-117. Sickel, J. B. 1986. Corbicula mortalities: factors influ encing control. American Submitted Malacological30 May 2006. Accepted 6 March 2007. Bulletin, Special Edition 2:89-94. Associate Editor was Joseph Shannon.
CHROMOSOMAL VARIATION IN NATURAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA INHABITING NORTHERN MEXICO
VICTOR M. SALCEDA,* JUDITH GUZMAN, OLGA OLVERA, AND Louis LEVINE
Departamento de Biologia, Instituto Nacional de Investigaciones Nucleares, Carretera Mexico, Toluca S/N, La Marquesa, Ocoyoacac, Mexico, C.P. 52000 (VMS, 00) Centro de Ciencias de la Atm6sfera, Universidad Nacional Aut6noma de Mexico, D.F. (JG) Department of Biology, City College of the City University of New York, New York, NY (LL) *Correspondent: vmss@nuclearinin. mx
ABSTRACT-Samples of 8 natural populations of Drosophila pseudoobscura inhabiting northern Mexico were cytogenetically analyzed. Twelve distinct chromosomal arrangements of the third chromosome were identified. Number of inversions at each locality varied from 6 to 8. A total of 468 third chromosomes were examined in the area of study, and relative frequencies of inversions in each population were calculated. The most common inversions in decreasing order of relative frequency were: TL, SC, OL, and CU; the other 8 inversions had frequencies <10%. Each locality had 3-4 inversions that accounted for '80% of the total. All populations were heterogeneous. Relative frequency of each inversion did not form a gradient along the transect studied. Unexpected was the presence of the ST inversion, as well as the incidence, in some populations, at a moderate frequency, of the inversion OL. Another exception was the increase in frequency of the EP inversion compared with previous collections in the area. More information from the region is needed.
RESUMEN-Muestras de 8 poblaciones naturales de Drosophila pseudoobscura que habitan en el norte de Mexico fueron analizadas citogeneicamente. Doce diferentes arreglos genicos o inversiones en el tercer cromosoma fueron detectados. El nuimero de inversiones en cada poblaci6n vari6 entre 6 y 8. Un total de 468 terceros cromosomas fueron analizados en el airea de estudio y la frecuencia relativa de las inversiones en cada poblaci6n fue calculada. Las inversiones mas comunes encontradas en orden decreciente a su frecuencia relativa fueron: TL, SC, OL y CU; las restantes 8 inversiones presentaron frecuencias menores al 10%. Cada localidad tuvo entre 3 y 4 inversiones representando hasta un 80% del total. Todas las poblaciones fueron heterogeneas. Las frecuencias relativas de cada inversi6n no formaron un gradiente en el transecto estudiado. Inesperada fue la presencia de la inversi6n ST asi como la presencia en algunas poblaciones, en frecuencias moderadas, de la inversi6n OL. Otra excepci6n fue el incremento en frecuencia de la inversi6n EP cuando comparada con colectas previas en el area. Mas informaci6n del area es requerida.
This content downloaded from 129.107.109.182 on Mon, 28 Aug 2017 20:57:42 UTC All use subject to http://about.jstor.org/terms