Paul E. Rothrock

Indiana University Bloomington, Bloomington, Indiana, United States

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Publications (20)21.18 Total impact

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    ABSTRACT: Carex (Cyperaceae), with an estimated 2000 species, nearly cosmopolitan distribution and broad range of habitats, is one of the largest angiosperm genera and the largest in the temperate zone. In this article, we provide argument and evidence for a broader circumscription of Carex to add all species currently classified in Cymophyllus (monotypic), Kobresia (c. 60 species), Schoenoxiphium (c. 15 species) and Uncinia (c. 70 species) to those currently classified as Carex. Carex and these genera comprise tribe Cariceae (subfamily Cyperoideae, Cyperaceae) and form a well-supported monophyletic group in all molecular phylogenetic studies to date. Carex as defined here in the broad sense currently comprises at least four clades. Three are strongly supported (Siderostictae, core Vignea and core Carex), whereas the caricoid clade, which includes all the segregate genera, receives only weak to moderate support. The caricoid clade is most commonly split into two clades, one including a monophyletic Schoenoxiphium and two small clades of species of Carex s.s., and the other comprising Kobresia, Uncinia and mostly unispicate species of Carex s.s. Morphological variation is high in all but the Vignea clade, making it extremely difficult to define consistent synapomorphies for most clades. However, Carex s.l. as newly circumscribed here is clearly differentiated from the sister groups in tribe Scirpeae by the transition from bisexual flowers with a bristle perianth in the sister group to unisexual flowers without a perianth in Carex. The naked female flowers of Carex s.l. are at least partially enclosed in a flask-shaped prophyll, termed a perigynium. Carex s.s. is not only by far the largest genus in the group, but also the earliest published name. As a result, only 72 new combinations and 58 replacement names are required to treat all of tribe Cariceae as a single genus Carex. We present the required transfers here, with synonymy, and we argue that this broader monophyletic circumscription of Carex reflects the close evolutionary relationships in the group and serves the goal of nomenclatural stability better than other possible treatments.
    Full-text · Article · Jul 2015 · Botanical Journal of the Linnean Society
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    ABSTRACT: From 2004 to 2012 a study of the flora and floral communities at Cabin Creek Raised Bog (Cabin Creek) was conducted. Cabin Creek, designated a National Natural Landmark by the National Park Service in December, 1974, is privately owned. It is located in west-central Randolph County, Indiana. An inventory of the vascular flora revealed 478 taxa representing 282 genera and 91 families. The 12 families containing approximately 62% of the documented species (in order by number of species) were Asteraceae, Cyperaceae, Poaceae, Rosaceae, Liliaceae, Lamiaceae, Scrophulariaceae, Apiaceae, Fabaceae, Ranunculaceae, Brassicaceae, and Polygonaceae. Of the 478 documented species, 400 were native, 78 were exotics, and 118 represented new Randolph County records. There were three species with Indiana Rare-Threatened-Endangered status, including Veratrum virginicum, (endangered), Triantha glutinosa (rare), and Melica nitens (threatened). A physiognomic analysis (i.e., summary of plant form or habit) is presented. The floristic quality index (FQI) for native species is 85.6 (78.3 for all species) and the mean coefficient of conservatism (mean C) for native species is 4.3 (3.6 for all species). These numbers clearly signify the "paramount importance" of the floral natural heritage of the approximately 7 ha Cabin Creek site and indicate that it is among the highest floristic quality sites in the state. The flora occurring in the major community types (wetland border/marshes, sedge meadow calcareous fen complex, moist prairie, mesic to dry woodland, moist woodland and hardwood swamp) is described.
    No preview · Article · Dec 2013 · Castanea
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    Paul E. Rothrock · Thomas P. Simon · Paul M. Stewart
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    ABSTRACT: We examine lacustrine wetland plant assemblages in the Central Corn Belt Plain portion of the Lake Michigan basin and developed a multimetric plant index of biotic integrity (PIBI). Our objectives were to determine the structural and functional attributes of littoral zone plant assemblages of least-impacted lacustrine wetlands, establish and test candidate metrics, statistically test and calibrate metrics, and finally validate a PIBI along a disturbance gradient. Of 35 candidate metrics, we chose 11 metrics that were grouped into four categories: species richness and composition, species tolerance, guild structure, and vegetation abundance. Based on Spearman correlations, we identified a suite of metrics, particularly those related to species richness and tolerance that had a strong response to human-induced habitat change. The overall PIBI correlated strongly with independent measures of habitat quality (p < 0.001) using a qualitative habitat index developed for lacustrine habitats. We validated the lacustrine PIBI by comparing index response to various landuse, landcover, and management types. Least impacted lakes and lakes classified as recreational or undergoing ecological restoration were not statistically separable and received the highest index scores, while the lowest scores were associated with industrial and residential land use. Least-impacted sites differ significantly (p < 0.001) from both industrial and residential lakes.
    Full-text · Article · May 2013 · Ecological Indicators
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    Paul E. Rothrock · Anton A. Reznicek · Charles T. Bryson
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    ABSTRACT: Carex molestiformis, described in 1997 as an endemic to the Ozark and Ouachita Mountain regions, is newly collected from Georgia, Mississippi, and Ohio. Herbarium records also have confirmed this species from North Carolina, Virginia, and West Virginia bringing the overall range of this species to 11 states. A morphological comparison of C. molestiformis from east of the Mississippi River with western populations did not reveal regional differences. Some eastern populations occupied ruderal habitat, namely drier grassy roadsides and hay meadows rather than the river bottom openings typical of western populations. New chromosome counts for this species from the eastern portion of its range confirmed existing reports of n = 37 and also found agmatoploidy with n = 35.
    Full-text · Article · Jun 2011 · Castanea
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    P. E. Rothrock · AA Reznicek · L. R. Ganion
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    ABSTRACT: The Carex straminea complex (section Ovales) consists of five species limited to hydric communities of eastern North America. Based upon gross morphology and perigynium structure, these species are closely aligned with the Carex albolutescens complex but not the western species Carex feta. An SEM investigation of the micromorphology of achene and style epidermis from 15 species of Carex section Ovales demonstrated much interspecific variation. As a result, these data could not confirm the relationship between the C. straminea complex and the C. albolutescens complex but did support the delimitation of section Ovales. Numerical analysis showed that characters of the inflorescence and perigynium are satisfactory for separating C. straminea from Carex hormathodes, a species limited to the Atlantic coast. Likewise, characters of inflorescence, pistillate scale, and perigynium could clearly separate the geographically widespread Carex alata from the Florida endemic species Carex vexans. A fifth and relatively distinctive species, Carex suberecta, was found to have a narrow ecological preference for fens and a distribution limited to the upper Midwest, with outlying populations in western Virginia. Putative natural hybrids are documented between Carex scoparia and Carex longii and some species in the C. straminea complex. Key words: Carex, Cyperaceae, section Ovales, taxonomy, SEM, biogeography, hybrid.
    Full-text · Article · Feb 2011 · Canadian Journal of Botany
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    Andrew L Hipp · Paul E Rothrock · Richard Whitkus · Jaime A Weber
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    ABSTRACT: Chromosome rearrangements may affect the rate and patterns of gene flow within species, through reduced fitness of structural heterozygotes or by reducing recombination rates in rearranged areas of the genome. While the effects of chromosome rearrangements on gene flow have been studied in a wide range of organisms with monocentric chromosomes, the effects of rearrangements in holocentric chromosomes--chromosomes in which centromeric activity is distributed along the length of the chromosome--have not. We collected chromosome number and molecular genetic data in Carex scoparia, an eastern North American plant species with holocentric chromosomes and highly variable karyotype (2n = 56-70). There are no deep genetic breaks within C. scoparia that would suggest cryptic species differentiation. However, genetic distance between individuals is positively correlated with chromosome number difference and geographic distance. A positive correlation is also found between chromosome number and genetic distance in the western North American C. pachystachya (2n = 74-81). These findings suggest that geographic distance and the number of karyotype rearrangements separating populations affect the rate of gene flow between those populations. This is the first study to quantify the effects of holocentric chromosome rearrangements on the partitioning of intraspecific genetic variance.
    Preview · Article · Aug 2010 · Molecular Ecology
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    Paul E. Rothrock · Anton A. Reznicek · Andrew L. Hipp
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    ABSTRACT: According to previous molecular study, the Carex tenera group sensu lato consists of C. tenera s. l. and C. normalis in one clade and C. festucacea, C. oronensis, and C. tincta in a sister clade. We found that Carex tincta, clarified by thorough review of herbarium materials, has a much narrower geographic range than previously thought, centering on Maine (U. S. A.), adjacent states, and adjacent portions of Canada with rare scattered occurrences to western Lake Superior. Carex tenera has traditionally been thought to consist of two varieties: the transcontinental variety tenera and the upper Midwest (U. S. A.) variety echinodes. In light of ecological and chromosomal differences, AFLP genetic distances, and morphological analysis the latter should be recognized as a distinct species, Carex echinodes comb. et stat. nov. Carex echinodes and narrow-leaved forms of C. normalis can be challenging to differentiate morphologically, but widest leaf width, inflorescence internode length, peduncle diameter, and growth habit separate the two taxa. New chromosome numbers are reported, with those of C. tenera (n = 24 + 2III, 26, 27, 28) having a lower range than either those of C. echinodes (n = 37, 38, 39) or C. normalis (n = 34, 35, 36).
    Full-text · Article · Jun 2009 · Systematic Botany
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    P E Rothrock · A A Reznicek · A L Hipp
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    ABSTRACT: According to previous molecular study, the Carex tenera group sensu lato consists of C. tenera s. l. and C. normalis in one clade and C. festucacea, C. oronensis, and C. tincta in a sister clade. We found that Carex tincta, clarified by thorough review of herbarium materials, has a much narrower geographic range than previously thought, centering on Maine (U. S. A.), adjacent states, and adjacent portions of Canada with rare scattered occurrences to western Lake Superior. Carex tenera has traditionally been thought to consist of two varieties: the transcontinental variety tenera and the upper Midwest (U. S. A.) variety echinodes. In light of ecological and chromosomal differences, AFLP genetic distances, and morphological analysis the latter should be recognized as a distinct species, Carex echinodes comb. et stat. nov. Carex echinodes and narrow-leaved forms of C. normalis can be challenging to differentiate morphologically, but widest leaf width, inflorescence internode length, peduncle diameter, and growth habit separate the two taxa. New chromosome numbers are reported, with those of C. tenera (n = 24 + 2III, 26, 27, 28) having a lower range than either those of C. echinodes (n = 37, 38, 39) or C. normalis (n = 34, 35, 36).
    Full-text · Article · Jan 2009
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    Andrew L. Hipp · Paul E. Rothrock · Eric H. Roalson
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    ABSTRACT: Sedges (Carex: Cyperaceae) exhibit remarkable agmatoploid chromosome series between and within species. This chromosomal diversity is due in large part to the structure of the holocentric chromosomes: fragments that would not be heritable in organisms with monocentric chromosomes have the potential to produce viable gametes in organisms with holocentric chromosomes. The rapid rate of chromosome evolution in the genus and high species diversification rate in the order (Cyperales Hutch., sensu Dahlgren) together suggest that chromosome evolution may play an important role in the evolution of species diversity in Carex. Yet the other genera of the Cyperaceae and their sister group, the Juncaceae, do not show the degree of chromosomal variation found in Carex, despite the fact that diffuse centromeres are a synapomorphy for the entire clade. Moreover, fission and fusion apparently account for the majority of chromosome number changes in Carex, with relatively little duplication of whole chromosomes, whereas polyploidy is relatively important in the other sedge genera. In this paper, we review the cytologic and taxonomic literature on chromosome evolution in Carex and identify unanswered questions and directions for future research. In the end, an integration of biosystematic, cytogenetic, and genomic studies across the Cyperaceae will be needed to address the question of what role chromosome evolution plays in species diversification within Carex and the Cyperaceae as a whole.
    Full-text · Article · Feb 2008 · The Botanical Review
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    Andrew L Hipp · Paul E Rothrock · Anton A Reznicek · Paul E Berry
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    ABSTRACT: Phylogenetic analysis of amplified fragment length polymorphisms (AFLP) was used to infer pat-terns of morphologic and chromosomal evolution in an eastern North American group of sedges (ENA clade I of Carex sect. Ovales). Distance analyses of AFLP data recover a tree that is topologically congruent with previous phylogenetic estimates based on nuclear ribosomal DNA (nrDNA) sequences and provide support for four species groups within ENA clade I. A maximum likelihood method designed for analysis of restriction site data is used to evaluate the strength of support for alternative topologies. While there is little support for the precise placement of the root, the likelihood of topol-ogies in which any of the four clades identified within the ENA clade I is forced to be paraphyletic is much lower than the likelihood of the optimal tree. Chromosome counts for a sampling of species from throughout sect. Ovales are mapped onto the tree, as well as counts for all species in ENA clade I. Parsimony reconstruction of ancestral character states suggest that: (1) Heilborn's hypothesis that more highly derived species in Carex have higher chromosome counts does not apply within sect. Ovales, (2) the migration to eastern North America involved a decrease in average chromosome count within sect. Ovales, and (3) intermediate chromosome counts are ancestral within ENA clade I. A more precise understanding of chromosomal evolution in Carex should be possible using likelihood analyses that take into account the intraspecific polymorphism and wide range of chromosome counts that characterize the genus.
    Full-text · Article · Jan 2007
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    J Balaban · P E Rothrock · A L Hipp · J Kluse · R Foster · L Ross · A A Reznicek

    Full-text · Book · Jan 2007
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    Andrew L. Hipp · Anton A Reznicek · Paul E. Rothrock · Jaime A Weber
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    ABSTRACT: Section Ovales is the most species-rich section of the sedge genus Carex in the New World. Phylogenetic analyses of molecular data recover a predominantly New World clade as sister to a solitary east Asian species, C. maackii. Nuclear ribosomal DNA are congruent in the placement of all taxa within the section, with a solitary exception: incongruence between ITS and ETS data in the placement of C. bonplandii and C. roraimensis suggests a hybrid origin for this lineage. Biogeography correlates strongly with phylogeny in the section, but there have been at least two instances of long-range dispersal, one from an eastern North American clade to western North America and one from the New World to Eurasia. Morphological characters studied are all homoplastic. Developing a comprehensive infrasectional classification with a phylogenetic basis would be complicated by the fact that most of the novel morphological characters in the section have evolved within relatively small, independent clades.
    Full-text · Article · Sep 2006 · International Journal of Plant Sciences
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    ABSTRACT: A short-term (approximately three hours) BioBlitz (rapid assessment of the species living in a particular area at one time) was conducted in the vicinity of Otter Creek, a tributary of the Wabash River in Vigo County, Indiana on 7 October 2005 . A total of 35 scientists and naturalists divided into aquatic, terrestrial animal, and terrestrial plant teams to survey different taxonomic groups . The teams recorded a total of 370 species : 205 plant species, 43 fungus, 9 insect, 8 bivalve, 2 crayfish, 52 fish, 6 amphibian, 34 bird, and 11 mammal species (with some additional aquatic and mammal sampling outside the three-hour period) . Species found were representative of the lower Wabash River drainage . BioBlitz events vary in scientific value, but can provide valuable scientific information as well as serve as a vehicle for public education about the natural world and conservation issues . We compare the results of the Otter Creek survey to other BioBlitz events in the Midwest .
    Full-text · Article · Jan 2006
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    Thomas P. Simon · Paul M. Stewart · Paul E. Rothrock
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    ABSTRACT: Riverine and palustrine wetland plant communities were examined in order to propose a multimetric plant index of biotic integrity. The objectives were to determine the structural and functional attributes of these wetland plant communities, calibrate reference conditions in assessing aquatic plant communities, provide methods for further development and testing of the index, and present a case study. The index is based on a rapid assessment method using the information collected from a species list and cover estimates. Sampling was done using a modified relevé sampling approach with a modified Braun-Blanquet Cover Abundance Scale Method for estimating percent cover. More than 20 characteristics of aquatic plant communities were evaluated and 12 metrics in five categories were developed. Structural metrics focused on community composition, key indicator species such as number of Carex and Potamogeton species, and guild type. Functional metrics included sensitivity and tolerance measures; percent emergent, pioneer, and obligate wetland species; and the number of weed species as a substitute metric. Abundance was estimated based on evenness of average cover densities. Individual condition was suggested as a measure of the lowest extremes of biotic integrity. Palustrine study sites ranged across a disturbance gradient from 'least-impacted' to 'poor'; riverine study sites ranged from high quality to some of the most degraded riverine sites in the Great Lakes region. Ninety-five species of aquatic vascular plants were found in 42 families. The most common families were Cyperaceae (15 species), Polygonaceae (9 species), and Juncaceae (6 species). Fourteen submergent, four floating, two woody and 75 emergent aquatic plant taxa were found. Five species were on the endangered, threatened, or rare list for the State of Indiana. Sites receiving the highest index scores included several of the a priori least-impacted sites while the lowest scores were located near-field to a large industrial landfill. The index will need to be further validated and tested but shows potential as a rapid index of biotic integrity using aquatic plant assemblages.
    Preview · Article · Sep 2001 · Aquatic Ecosystem Health and Management
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    Paul E. Rothrock · AA Reznicek
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    ABSTRACT: Based on morphology and karyology, we found the eastern North American species Carex bicknellii (sect. Ovales) to be a complex of four species. We describe two new species, C. missouriensis and C. shinnersii, and raise one variety, C. bicknellii var. opaca, to species rank as C. opaca. The three species segregated from C. bicknellii have lower chromosome numbers: n = 23 II + 1 III to 27 II for C. missouriensis, n = 29 II + 1 III to 30 II for C. shinnersii, and n = 32 II + 1 III to 34 II for C. opaca. All three species are characterized by large tussocks, herbaceous textured foliage and smooth sheaths, and long apiculum on the achenes; they occupy hydric habitats. Carex missouriensis, a species characterized by awned pistillate scales, grows in remnant prairie swales from western Indiana to southeastern Nebraska. Carex opaca, with blunt scales and large perigynia, has a narrow distribution mostly limited to the periphery of the Ozark Mountain system. Carex shinnersii, with acuminate but unawned scales and perigynia smaller than C. opaca and C. missouriensis, ranges from northern Texas to southern Kansas. This last species is also contrasted with C. brevior, a species with similar morphology and overlapping range. Carex bicknellii in the strict sense is morphologically similar to the northeastern species C. merritt-fernaldii. They both have few culms per tussock, coriaceous foliage with papillose sheaths, papery, erose-margined perigynia, achenes with a very short apiculum, and relatively high chromosome numbers (n = 35 II to 39 II). These two species differ in characters of the anther, achene, and perigynium. They occupy more or less xeric habitats, especially in the Central Plains of the United States (C. bicknellii) and southern Canada eastward from the Great Lakes region (C. merritt-fernaldii).
    Full-text · Article · Jun 2001 · Novon A Journal for Botanical Nomenclature
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    P.E. Rothrock · A.A. Reznicek
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    ABSTRACT: Chromosome counts for 14 species of Carex section Ovales are documented completing at least a single report for each of the over 40 species known for eastern North America. The haploid numbers in this report ranged from n = 24 to n = 42. Counts for Carex feta, C. muskingumensis, C. oronensis, and C. tetrastachya were determined for the first time and six aneuploid (sensu lato) series are indicated. The only previously published counts for C. adusta, C. argyrantha, and C. foenea (C. aenea) were found to be incorrect.
    Full-text · Article · Dec 1998
  • P.E. Rothrock · A.A. Reznicek
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    ABSTRACT: Chromosome counts for seventeen species of Carex section Ovales are reported. They range from n=26 + IV to n=40. Counts for Carex alata, C. hyalina, C. longii, C. ozarkana, C. reniformis, C. suberecta, C. tincta, and C. vexans were determined for the first time and included 3 aneuploid (sensu lato) series. Four species (C. albolutescens, C. hormathodes, C. straminea, and C. tribuloides) yielded counts similar to previously published results. On the other hand, two species (C. cumulata and C. silicea) differed from previous reports and represent possible aneuploidy, while aneuploidy was demonstrated for C. festucacea.
    No preview · Article · Jan 1996
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    Paul E. Rothrock · A. A. Reznicek
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    ABSTRACT: Carex ozarkana, a new species from Arkansas, Oklahoma, and extreme northeasternmost Texas is described and illustrated. It is a distinctive regional endemic of mineral soil wetlands most similar to the widespreadCarex albolutescens andC. longii but differing in its elongate, nodding inflorescences (on robust plants), prominently clavate spikes with elongate staminate bases, reddish brown pistillate and staminate scales, and wider achenes with a long apiculum.
    Full-text · Article · Dec 1995 · Brittonia
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    Paul E Rothrock · Thomas P Simon

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