Whitkus, Richardhttp://hdl.handle.net/10211.1/8582024-03-29T09:54:03Z2024-03-29T09:54:03ZGenetics of Adaptive Radiation in Hawaiian and Cook Islands Species of Tetramolopium (Asteraceae; Astereae) : I. Nuclear RFLP Marker DiversityOkada, M. R.Whitkus, RichardLowrey, T. K.http://hdl.handle.net/10211.1/8592013-09-11T16:04:11Z1997-01-01T00:00:00ZGenetics of Adaptive Radiation in Hawaiian and Cook Islands Species of Tetramolopium (Asteraceae; Astereae) : I. Nuclear RFLP Marker Diversity
Okada, M. R.; Whitkus, Richard; Lowrey, T. K.
Thirty-three nuclear RFLP (restriction fragment length polymorphism) probes were used to study genetic diversity in
Hawaiian and Cook Islands species of Tetramolopium for comparison with previous morphological and isozyme studies and
to provide greater resolution of the events associated with adaptive radiation in the genus. Levels of RFLP diversity are
greater than those reported for isozymes, yet are still low in comparison to continental species. Genetic differentiation is
greatest among species in sections rather than among sections and is concordant with the hypothesis of phyletic sorting of
initial variability as suggested for morphological traits. Hypothesized introgression between T. lepidotum and T. filiforme is
supported, but the evidence suggests bidirectional gene flow. Systematic relationships derived from the data agree with
hypotheses based on morphology in the placement of populations within their respective species and the recognition of
three main lineages within Hawaii. Inclusion of the Cook Islands species, however, renders section Tetramolopium paraphyletic,
contradicting morphological, ecological, and crossing evidence. Interpreting these results in light of evidence from
previous studies, the genetic diversity and relationships seen among species and sections of Hawaiian and Cook Islands
Tetramolopium reflect the recent and rapid evolution of this group, limited addition of new variability, and phyletic sorting.
Published by and copyright of the Botanical Society of America. The definitive version of this article is available at http://www.amjbot.org/content/84/9/1236.full.pdf+html?sid=52169850-4ff7-466d-b182-5388a7e7d10e
1997-01-01T00:00:00ZChromosome Counts of Carex Section OvalesWhitkus, Richardhttp://hdl.handle.net/10211.1/8772014-01-29T08:24:51Z1991-01-01T00:00:00ZChromosome Counts of Carex Section Ovales
Whitkus, Richard
Chromosome counts for eight species of Carex section Ovales were determined (c. bebbii, C. crawfordii,
C. integra, C. microptera, C. pachystachya, C. praticola, C. preslii, and C. subfusca). Combined with data
from previous studies in the sect. Ovales, chromosome number variability is observed within individuals,
populations, and species. Counts from 10 sib families of C. pachystachya indicate that structural rearrangements
occur between generations. A total of 38 of the approximately 70 species of the section have
been counted. Sixteen species have been counted more than once: seven of these show no chromosome
number variation and nine have aneuploid series of numbers. Two forms of chromosome change are
identified in the section: structural rearrangements and aneuploidy. At present the data cannot be used
to determine whether strict aneuploidy or agmatoploidy accounts for the aneuploid variation.
Published by and copyright of J.M. Coulter Publishing, Hanover, Indiana
1991-01-01T00:00:00ZBiochemical Basis of Floral Color Polymorphism in a Heterocyanic Population of Trillium SessileLes, Donald H.Whitkus, RichardBryan, F. A.Tyrell, L. E.http://hdl.handle.net/10211.1/8762014-01-29T08:24:50Z1989-01-01T00:00:00ZBiochemical Basis of Floral Color Polymorphism in a Heterocyanic Population of Trillium Sessile
Les, Donald H.; Whitkus, Richard; Bryan, F. A.; Tyrell, L. E.
A study of flavonoids occurring within a heterocyanic population of Trillium sessile was made
to determine the chemical basis of a common floral color polymorphism in this species. In the
study population, three floral color phenotypes (red, pink, yellow) are determined primarily by
the presence or absence of anthocyanin compounds in the petal tissue, and secondarily by
quantitative differences in the concentration of several flavonol glycosides. Petals of red phenotypes
contain both cyanidin 3-arabinoside and 3-diarabinoside, petals of pink phenotypes
contain only cyanidin 3-arabinoside, and petals of yellow phenotypes lack cyanidin entirely.
Quercetin 3-0-glucoside, quercetin 3-0-arabinoglucoside, quercetin 3-0-arabinogalactoside, and
quercetin 3-0-arabinogalactosyl, 7-0-glucoside occur in petals of all three phenotypes but differ
in relative amounts. Petals of the red phenotype have mostly 3-0-biosides, but lesser amounts
of both quercetin 3-0-glucoside and the 3,7-0-triglycoside. Petals of the pink phenotype contain
relatively equal amounts of quercetin mono-, di-, and triglycosides. Petals of the yellow phenotypes
contain mostly quercetin 3,7-0-triglycosides, and less mono- and di-glycosides. Small
amounts of a quercetin tetraglycoside were detected in petals of both yellow and pink phenotypes,
but not in red phenotypes. The enhancement of quercetin polyglycoside biosynthesis in yellow
petal phenotypes is attributed to the shunting of dihydroflavonol precursors to synthesis of
quercetin compounds when their conversion to anthocyanins is blocked genetically.
Published by and copyright of the American Journal of Botany. The definitive version of this article is available at http://www.jstor.org/stable/2444769
1989-01-01T00:00:00ZA Numerical Analysis of Flavonoid Variation in Arnica Subgenus Austromontana (Asteraceae)Wolf, Steven J.Whitkus, Richardhttp://hdl.handle.net/10211.1/16102014-10-02T04:41:17Z1987-02-01T00:00:00ZA Numerical Analysis of Flavonoid Variation in Arnica Subgenus Austromontana (Asteraceae)
Wolf, Steven J.; Whitkus, Richard
Species of Arnica subgenus Austromontana produce a total of 23 leaf flavonoids, including
simple and methylated flavone and flavonol glycosides as well as highly methylated flavone
aglycones and a 6-hydroxylated flavone. Most of the taxa exhibit considerable interpopulational
variability, with the number of compounds per population ranging from 2 to 14. Analysis of
flavonoid variation in 1 3 populations representing all 9 species of the sub-genus was carried
out using cluster analysis, principal components analysis, and binary discriminant analysis.
Results indicate the flavonoid profile of the very rare A. viscosa is the most distinctive in the
subgenus. Although exhibiting considerable interpopulational variability, all populations of A.
gracilis, a hybrid taxon, form a very distinct and cohesive group, supporting its recognition at
the specific level. Additionally, chemical diversification from A. cordifolia has taken place largely in the Klamath region of Oregon and California. The range of variability exhibited by A. cordifolia
is reflected in these Klamath region derivatives.
Published by and copyright of the Botanical Society of America. The definitive version of this article is available at http://www.jstor.org/stable/2444051
1987-02-01T00:00:00Z