Allozymic variation in nine protein producing loci was examined in three species of Pardosa using starch gel electrophoresis. Allozyme frequencies showed a high degree of geographic uniformity among conspecific populations. Estimated heterozygosities for the three species ranged from 0.05 to 0.15. Rogers\u27 coefficients of genetic similarity based on allozyme frequencies averaged over conspecific populations ranged from 0.16 to 0.37 fo rthe three species

Elliott, N. C

Engemann, J. G

Johnson, W. E

Wolff, R. J

English

ValpoScholar

Genetic Differentiation Among Three Species of \u3ci\u3eParadosa\u3c/i\u3e (Arachnida: Lycosidae)

Valparaiso University

The Great Lakes Entomologist Volume 15 Number 1 - Spring 1982 Number 1 - Spring 1982 Article 9 April 1982 Genetic Differentiation Among Three Species of Paradosa (Arachnida: Lycosidae) N. C. Elliott Michigan State University R. J. Wolff Trinity Christian College W. E. Johnson Case Western Reserve University J. G. Engemann Western Michigan University Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Elliott, N. C.; Wolff, R. J.; Johnson, W. E.; and Engemann, J. G. 1982. "Genetic Differentiation Among Three Species of Paradosa (Arachnida: Lycosidae)," The Great Lakes Entomologist, vol 15 (1) Available at: https://scholar.valpo.edu/tgle/vol15/iss1/9 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1982 THE GREAT LAKES ENTOMOLOGIST 55 GENETIC DIFFERENTIATION AMONG THREE SPECIES OF PARDOSA (ARACHNIDA: L YCOSIDAE) N. c. Elliott, I R. J. Wolff,2 W. E. Johnson,3 and J. G. Engemann4 ABSTRACT AlJozymic vanatlOn i nine protein producing loci was examined in three species of Pardosa using starch gel electrophoresis. Allozyme frequencies showed a high degree of geographic uniformity among conspecific populations. Estimated heterozygosities for the three species ranged from 0.05 to 0.15. Rogers' coefficients of genetic similarity based on allozyme frequencies averaged over conspecific populations ranged from 0.16 to 0.37 forthe three species. Pardo sa are active wandering spiders of the family Lycosidae, the wolf spiders. About 50 species are known from North America, but many are morphologically similar and difficult to identify. This is especially true for the majority of species that occur in the western United States. Additional taxonomic characters would be valuable in reducing systematic confusion. Allozymic variation in proteins is a useful tool for investigating systematic relationships of closely related species (Avise 1974). Allozymic variation n the proteins commonly ex­amined has a simple genetic basis. While it is recognized that more genetic variation may be present at most loci than can be detected by electrophoretic techniques, electrophoretic studies yield useful information concerning levels of genetic variation within and among species of animals and plants. In general, studies indicate a high degree of genetic similarity among conspecific populations. Nei (1978) has shown that it is often possible to adequately characterize the total a1lozymic variation within a species from one or a few population samples. Congeneric species generally show much lower levels of genetic similarity than do conspecific popUlations. Comparisons among congeneric species yield phenetic groupings which usually correspond closely with those derived by classical methods (Avise 1974). The purpose of this study is to assess the potential value of electrophoretic data as a taxonomic tool within the Pardosa and to compare the level of allozymic variability in the genus with levels of a1lozymic variability observed in other animal groups. MATERIALS AND METHODS This study was based on ]59 specimens representing three species of Pardosa collected during the summer of 1976. Pardosa moesta Banks was collected from four locations: Mott Preserve, Van Buren Co., MI, the Kalamazoo Nature Center, Kalamazoo Co., MI, roadside grass, Chippewa Co., MI, and City of Marquette, Marquette Co., ML Pardosa milvina Hentz was sampled from two locations: Standing Stone State Park, Clay Co., TN, and Wildwood Trailer Park, Jackson Co., IL. Pardosa distincta Blackwall was collected from two locations: roadside grass, Luce Co., MI, and the City of Marquette, Marquette Co., ML Specimens were collected within an area of approximately 100 m2 and returned to the laboratory alive; they were then stored at -70"C until just prior to electrophoresis at which time the animals were individually homogenized in 0.1 ml 0.2 M Tris HCI, pH 7.8. The IEntomology Department, Michigan State University. East Lansing, MI 48824. 2Biology Department, Trinity Christian CoUege, 6601 West College Drive. Palos Heights. IL 60463. 3Genetics Center, Case Western Reserve University. 2119 Abington Rd .. Cleveland, OH 44101. 4Biology Department, Western Michigan University. Kalamazoo, MI 49008. 1Elliott et al.: Genetic Differentiation Among Three Species of <i>Paradosa</i> (APublished by ValpoScholar, 198256 THE GREAT LAKES ENTOMOLOGIST VoL 15, No. I homogenate was absorbed onto two smail rectangular pieces of No. 3 filter pa er and applied to two horizontal starch gels. Electrophoresis and histochemical staining were per­formed as described by Selander et aL (1971) and Brewer (1970). Samples were assayed using two buffer systems. Isocitrate dehydrogenase (IDH-l and IDH-2), lactate dehydro­genase (LDH), a-glycerophosphate dehydrogenase (a-GPD), and hexokinase (HK) were resolved using buffer system No.5 (Selander et at., 1971). Phosphoglucose isomerase (PGI). phosphoglucomutase (PGM), and general protein (Pf-2 and Pf-4) were resolved using buf­fer system No.2 (Selander et aI. 1971). All proteins migrated anodally on the buffer systems used. Allozymes at a particular locus were alphabetized according to their relative mobilities on the specified electrophoretic buffer systems, without regard for species; the fastest migrat­ing allozyme was designated (a) while correspondingly slower allozymes were designated b. c, and so on. Determinations of identity and non-identity were made on the basis of side by side comparisons r near juxtaposition on the same geL Standards containing the most common allozymes occurring at each protein system for oesta and milvina were placed at various locations on each gel to insure that frequently encountered a1lozymes were not misidentified. Low frequency allozymes at each protein for which direct comparisons could not be made were grouped into one class designated (other) in Table I; allozymes in this class were not included in comparisons of genetic similarity among species. Rogers' coefficient of genetic similarity (Rogers 1972) was used to estimate the degree of genetic similarity among the three species. The genetic interpretation of our results was inferential since progeny studies were not undertaken. However, our results were supported by the general agreement of genotypic frequencies with those expected under conditions of Hardy-Weinberg equilibrium and by patterns of allozymic variation in other animal species. Table I. Sample size and allozyme frequencies for nine variable proteins in eight populations representing three species of Pardosa. Populationa Protein Allozyme 2 3 4 5 6 7 8 Sample size 30 26 II 15 30 27 II 9 PGI Pgia Pgib .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .09 .45 ,17 .05 PgiC Pgid .00 .07 .00 .08 .00 .09 .00 .07 .00 .05 .13 .00 .00 .00 .00 .00 Pgie Pgif .00 .93 .00 .90 .00 .86 .00 .90 .00 .93 .00 .83 .41 .00 .78 .00 other .00 .02 .05 .03 .02 .04 .05 .00 PGM Pgma .00 .00 .00 .00 .00 .00 .09 .10 Pgmb .95 .94 .94 .94 .00 .00 .32 ,33 PgmC Pgmd other .00 .00 .05 .00 .00 ,(16 .00 .00 .06 .00 .00 .06 .00 .93 .07 .00 .93 ,07 .55 .00 .04 .53 .00 .04 !DH-I Idh-la 1.00 1.00 .95 1.00 .03 .09 .90 .56 Idh-Ib .00 .00 .00 .00 .90 .91 .00 .00 Idh-ld .00 .00 .00 .00 .00 .00 .05 .44 other .00 .00 .05 .00 .07 .00 .05 .00 2The Great Lakes Entomologist, Vol. 15, No. 1 [1982], Art. 9https://scholar.valpo.edu/tgle/vol15/iss1/91982 THE GREAT LAKES ENTOMOLOGIST 57 Table I. (Continued) Population a Protein Allozyme 2 3 4 5 6 7 8 IDH-2 Idh-2a .97 .92 .95 .90 .00 .00 .00 .00 Idh-2b .00 .00 .00 .00 .00 .00 1.00 1.00 Idh-2c .03 .04 .05 .10 1.00 1.00 .00 .00 Idh-2d .00 .04 .00 .00 .00 .00 .00 .00 a-GPD a-Gpda a-Gpdb 1.00 .00 1.00 .00 1.00 .00 1.00 .00 .00 .97 .00 .98 .00 .00 .00 .00 a-Gpdc .00 .00 .00 .00 .00 .00 1.00 1.00 other .00 .00 .00 .00 .03 .02 .00 .00 LDH Ldha .97 1.00 1.00 .93 .00 .26 .00 .00 Ldhb .00 .00 .00 .00 .13 .00 .00 .00 Ldhd .00 ,00 .00 .00 .85 .74 1.00 1.00 other .03 .00 .00 .07 .02 .00 .00 .00 HK Hka 1.00 .98 1.00 1.00 .00 .00 .00 .00 Hkb .00 .00 .00 .00 .97 1.00 1.00 1.00 other .00 .02 .00 .00 .03 .00 .00 .00 PT-2 1.00 1.00 1.00 1.00 1.00 1.00 .00 .00 .00 .00 .00 .00 .00 .00 1.00 1.00 PT-4 Pt-4a I.OO 1.00 1.00 1.00 1.00 I.OO .00 .00 Pt-4b .00 .00 .00 .00 .00 .00 1.00 1.00 al_p. moesta, Mot! Reserve, Van Buren Co., MI; 2-P. moesta. Kalamazoo Nature Center. Kalama· MI: 3-P. moesta. roadside grass. Chippewa Co. MI: 4--P. moesta. City of Marquette. Mar-MI; 5-P. milvina, Standing Stone State Park. TN; 6-P. milvina. Wildwood Trailer Park, Co., IL; 7-P. distincta. roadside grass, Luce MI; S-P. disrinc/a, City of Marquette. Marquette Co .. ML RESULTS AND DISCUSSION Allozyme frequencies and sample size for the nine proteins studied are shown in Table I. One allozyme predominated in all populations of a species at most proteins; however, in distincta two allozymes were present in varying frequencies at PGI and IDH-1. There was some sharing of alIozymes among species. i.e. Idh·la was found in all three species and Pgid, Pt-za. Pt-4a, Idh-Zc Hk b, Ldh a. Ldh c, and Pgmb were found in two species. The geographic pattern of allozyme frequencies within each of the three species show d a high degree of uniformity. This pattern i typical fOf animal species with high dispersal abilities (Sou e 1976). Pardosa are active dispersers with frequent observation of ballooning in which the spiders spin out silk and are picked up and carried long distances by the wind. The estimated average levels of heterozygosity (H) based on the nine proteins studied were 0.05, 0.10, and 0.15 for moesta, milvina, and distincta. respectively. Because levels of heterozygosity vary widely among loci, estimates of H based on small numbers of loci must be interpreted cautiously. However. it has become apparent from the numerous studies that have been completed that not all types of organisms re equally variable (Selander 1976). 3Elliott et al.: Genetic Differentiation Among Three Species of <i>Paradosa</i> (APublished by ValpoScholar, 198258 THE GREAT LAKES ENTOMOLOGIST Vol. 15, No. I Table 2. Rogers' coefficients of genetic similarity among three species of Pardosa. moesta milvina distincta moesta 1.000 0.371 0.157 milvina 0.371 1.000 0.260 distincta 0.157 0.260 1.000 The estimated level of heterozygosity for the three species of Pardosa (H 0.10) was similar to that found for ther invertebrate species groups (Nevo 19781. Estimates of genetic similarity (S) among the three species ranged from 0.16 to 0.371Table 2) with a mean across species (S) of 0.27. Most groups of closely related congeneric species studied show somewhat higher estimates of S (Avise 1974). The low estimate of S for the three Pardosa species may have been due to the chance selection of proteins for our study which ere highly differentiated in Pardosa. Perhaps the study ofaddit:ioIla.I proreins would have resulted in an increased estimate of average genetic similarity. Alternath"e!y. the low estimate of S for the three species may reflect a truly high level of genetic divergence amongthe species in spite of considerable external morphological similarity ...oJ! three species occur in similar habitats and it is possible that selection for similar external morphology has obscured a high level of genetic divergence among the species. In our study a-G PD served as a diagnostic taxonomic criterion for differentiating the three species, since no two species shared common allozymes at that locus....1liIe the probability of miscIassifying a species using IDH-2 as a criterion was no greater than 0.01. Ifahigh level of divergence in allozymes is characteristic of the genus as a Whole. it is coocei\"abIe that relatively few protein-producing loci could serve as a taxonontic basis for differentiating species in the genus. ACKNOWLEDGME1'.'TS This research was completed while the authors were located at the Biology Department of Western Michigan University. Thanks go to Janice E. Elliott for ber secretarial assistance and her help in collecting specimens. LITERATURE CITED Avise, J. C. 1974. The systematic value of el ctrophoretic data. Syst. Zoo!. ~A65-181. Brewer, G. 1. 1970. Introduction to isozyme techniques. Academic Press. ~'l'. Nei, M. 1978. Estimation of average heterozygosity and genetic distance from a small number of individuals. Genetics. 89:583-590. Nevo, E. 1978. Genetic variation in natural populations: Patterns and theory. Theor. Pop. BioI. 13: 121-177. Rogers, 1. S. 972. Measures of genetic similarity and genetic distance. Srudies in Genetics VII. Univ. Texas PubL 7213:145-153. Selander, R. K. 1976. Genic variation in narural populations. p. 21-45 in F. J. Ayala fro. I. Molecular evolution. Sinauer Associates, Inc., MA. Selander, R. K., M. H. Smith, S. Y. Yang, W. E. Johnson. and 1. B. Gentry. 1971. Bio­chemical polymorphism and systematies in the genus Peromyscus. 1. Variation in the old-field mouse (Per m cus polionotus). Studies in Genetics VII. Univ. Te;>;as Publ. 7103:49-90. Soule, M. 	1976. Allozyme variation: its determinants in space and time. p. 1YJ-77 in F. J. Ayala (ed.). Molecular evolution. Sinauer Associates, Inc., MA. 4The Great Lakes Entomologist, Vol. 15, No. 1 [1982], Art. 9https://scholar.valpo.edu/tgle/vol15/iss1/9

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Genetic Differentiation Among Three Species of \u3ci\u3eParadosa\u3c/i\u3e (Arachnida: Lycosidae)

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