Michael A. Romano

Effects of Twenty Years of Hybridization in a Disturbed Habitat on Hyla cinerea and Hyla gratiosa

Field, acoustical, morphological, and electrophoretic analyses confirmed that more than 20 years after it began due to pond construction, hybridization between Hyla cinerea and H. gratiosa persists near Auburn, Alabama. Hyla gratiosa males began calling three weeks before H. cinerea or hybrids appeared at the ponds. Electrophoretic analysis demonstrated that the first back- crossed animals found in the breeding season were backcrossed towards H. gratiosa, while F, hy- brids and H. cinerea-like backcrossed animals appeared later. Morphological and electrophoretic identification of treefrogs generally coincided; however, 38% of individuals morphologically iden- tified as H. cinerea were electrophoretically H. cinerea backcrosses. The data indicate that F1 hy- brids, and possibly backcrossed individuals, may have reduced fitness.

POPULATION GENETICS AND SYSTEMATICS OF THE MORCHELLA ESCULENTA COMPLEX

Allelic frequencies for strains of an early occurring gray form of Morchella and the tan M. esculenta were determined for collections from west central Illinois and southwestern Wisconsin. Horizontal starch gel electrophoresis was used to determine electromorph (allele) frequencies from fourteen enzyme systems encoded by twenty presumptive structural loci. A total of 122 monoascosporous isolates from 72 ascocarps were studied. Electrophoretic polymorphisms were found in strains of both forms demonstrating that they exist as Mendelian populations. In general, the gray form and M. esculenta had a high genetic similarity when they occurred at the same locality, indicating that they were likely derived from a common ancestral population. The Plymouth strains were genetically more similar to the Eagle Township strains than the strains from the Richland Center area, which had a larger separation than the other collections. Geographic distance between Illinois and Wisconsin strains resulted in substantial genetic differentiation attributable to genetic drift (Fst = 0.165). Strains ofthe two different forms, however, do not cluster separately in a phenetic analysis indicating that the two phenotypes are not different taxa.

ALLELIC VARIATION AND SEGREGATION IN MORCHELLA DELICIOSA AND M. ESCULENTA

Electrophoretic data were obtained for single ascospore isolates ofMorchella deliciosa from individual ascocarps. The loci studied exhibited allelic differences between ascospore isolates, indicating that genes from different paternal genomes exist in individual offspring from a single ascocarp. Less genetic variation was found in M. esculenta but ascospore isolates from individual ascocarps also exhibited allelic differences. The occurrence of only two electrophoretic types was observed among the six isolates and may indicate the existence of linkage or pseudolinkage. The presence of polymorphisms, the possibility of mating types and production of ascospores indicate that M. deliciosa and M. esculenta exist as Mendelian populations. The occurrence of gene exchange among sexually reproducing individuals enables a biological basis for determining taxa. Our data also indicate that local populations of M. deliciosa and M. esculenta can be reproductively isolated and exist as separate gene pools.

Turtle Habitat Use in a Reach of the Upper Mississippi River

Abstract Turtle community composition was determined in three habitats—open river, slough, and backwater—of the Mississippi River near Hamilton, Illinois. While seven species of turtles were collected during the study, distinct communities were found in each of the habitats. The open river site was dominated by female smooth softshell turtles, Apalone muticas, which made up approximately 80% of the community in this habitat. While turtles were abundant in the backwater habitat, only three species, red-eared slider (Trachemys scripta), common snapping turtle (Chelydra serpentina), and painted turtle (Chrysemys picta), were collected. Though all three species were common in the backwater, the red-eared slider was the most abundant. The habitat with the most abundant and diverse turtle community was the slough. In addition to red-eared sliders, the most abundant species collected, common snapping turtles, painted turtles, smooth softshell turtles, spiny softshell turtles (Apalone spinifera), common map turtles (Graptemys geographica), and false map turtles (G. pseudogeographica), were also collected in this habitat. The slough habitat had permanent water with low current velocities and abundant basking and refuge sites, which provide the best conditions for most of the turtle species collected.

Parallel Electromorph Variation in the Diploid-Tetraploid Gray Treefrog Complex

The tetraploid treefrog Hyla versicolor and its diploid progenitor, H. chrysoscelis, are extremely similar morphologically and ecologically, and they share virtually all of the same major protein polymorphisms. Sympatric populations of H. versicolor and H. chrysoscelis were sampled from widely separated localities in Texas, Oklahoma, Missouri, Illinois, and the Indiana-Ohio area. The data were analyzed by means of a statistic that measured the degree to which the two species parallel one another in terms of electromorph frequency. Of 11 polymorphic loci, 5 were significantly correlated (P < 0.05), and 3 more bordered on significance. Several explanations for these results are possible: parallel selection for shared electromorphs in similar environments, extensive gene flow between ploidy levels in areas of contact, multiple origins of the tetraploid in different areas of the diploid range, and some combination of these possibilities. Available data suggest that natural selection is the major factor responsible for parallel patterns of electromorph frequencies.

Systematics of Morchella esculenta complex using enzyme-linked immunosorbent assay

Enzyme-linked Immunosorbent assay (ELISA) was used to study the immunological relationships among strains in the Morchella esculenta complex. Two strains of M. semilibera were chosen as outgroups for comparison. Mycelial extracts were used as antigens to induce antisera production in rabbits. The range of titers from ELISA were 1:128 to 1:2048. Serologic data from ELISA were analyzed based on the Titer and the Best-fit Line methods. Cross-reactivity at a specific titer did not differentiate the species. Dendrograms, however, based on the Best-fit Line method had all strains ofthe M. esculenta complex cluster together and sort out separately from the M. semilibera strains. The Prager and Wilson F values for the Titer method trees (UPGMA = 10.74, Fitch-Margoliash = 17.89) were higher than those for the Best-fit Line method trees (UPGMA = 5.93, Fitch-Margoliash = 11.81) within each analysis indicating the trees from the Best-fit Line method were more parsimonious. No significant differences were found between UPGMA and the Fitch and Margoliash method in terms of tree topology. Phylogenetic trees have not been commonly used with ELISA data. Combining the highly specific and sensitive ELISA with numerical taxonomic and phylogenetic techniques can provide additional sys? tematic insights. The results of this study indicate that the gray, tan and large tan forms in the M. esculenta complex are immunologically indistinguishable and likely conspecific.

Population genetics and systematics of marine species of Dendryphiella

The deuteromycetes Dendryphiella arenaria and D. salina occur on macroalgae and plant debris in marine habitats. Strains from 17 locations in Canada, New England, the Southeast, Pacific Northwest and Europe were isolated from beaches and salt marshes or obtained from culture collections. The relationships between the species and the degree of genetic variability among different populations were studied. Starch-gel electrophoresis was used to analyze electromorph variation from 11 enzyme systems encoded by 14 presumptive structural loci. Strains of D. salina from different localities had identical electromorph patterns except for 3 strains isolated from Shelter Cove, California. All strains identified as D. arenaria differed from D. salina for four enzyme systems. Our data demonstrate that consistent genetic differences exist between the taxa and support the retention of two species. Some strains could not be placed with certainty in either species because of overlapping morphological characteristics; however, electrophoretic results indicate that all of these belonged to D. arenaria. The genetic variability observed was very low compared to other organisms including fungi. Our electrophoretic data indicate that both D. arenaria and D. salina are generalists and it is unlikely they have teleomorphs.

Responses to Desiccation of the Treefrogs Hyla cinerea and H. gratiosa and Their Natural Hybrids

-The responses to desiccation of adult Hyla cinerea, H. gratiosa and their hybrids were measured. Hyla gratiosa tolerated significantly (P < 0.05) more water loss longer than H. cinerea. Hybrids showed intermediate responses but only the time required to complete desiccation was directly proportional to their genetic contribution from the two parental species. These results suggest that lim itations in physiological capacities are not restricted by the inheritance of a single gene but rather are the product of polygenic inheritance. Previously reported evidence of natural selection against hybrids does not appear to be linked to the water relations of these frogs in any overt fashion.