DOCUMENTED CHROMOSOME NUMBERS 2002:3. CHROMOSOME COUNTS FOR PACKERA PAUPERCULA VAR. APPALACHIANA (ASTERACEAE: SENECIONEAE)

6 Pages·2002·3.4 MB·English

by  Alison Mckenzie Mahoney

DOCUMENTED CHROMOSOME NUMBERS
2002:3.
CHROMOSOME
COUNTS FOR PACKERA PAUPERCULA
VAR.
APPAEACHIANA (ASTERACEAE; SENECIONEAE)
Mahoney Kong
McKenzie W.
Alison Virginia
Deportment
of Biological Sciences
Minnesota State University-Mankato
Monkato,MN
56001,
U.S.A.
Robert R.Kowal
'ison,WI53706,U.
ABSTRACT
a species of the'Great Plains, which mcly have migrated into the mid Appalachians during
ttt-nsis,
post-glacial Hypsither mic Period an >d there as relict However. Rplattens IS is tetraploid
s.
two chrom.osome
jr ex
n Virginia are n = 22 ind n - ca. 44 respect ively a diploid and a tetraploid, botih with X - 22.
£
.
tist.cal analyses of poll .idence that the other individuals in the two popu-
Rauream;
ons are diploid and mostly tetraploic respect Ively Hybridiz;ation with
1,
mg
show
he origin of the tetraploid.Tfius,cy tological evidence supp.orts other data that these
itoPp.,
closely relatec q^ercula.
RESUMEN
rtas poblaciones de Pa ckera (Asteraceae: Serlecioneae) mas menos tomentosas del sureste de
America han ementec:omo Rpauperc ulavaT.appalachiana basandoseen
side
-te tr
un sprehminarcieRAPDs,ycruces.Prev iamentehabiansidoi:ratadoscomo
atos lorales, analisi
f
juntas deEplattensis,u,laespeciede Grande;sLlanuras,queiDodriahabermigradosilosApalaches
las
R
doaUlcomorelicto.S embargo,
dies durante el periodo^hipsitermico cial y sobrevivi in
Nuestt :romosomaticosdelarluevavariedad
ttensisestetraploidecon
22yn-.
amente,undiploidey
/irginiasonn- ca.44,respectiv untetraploide,
bos con X- 22. Los anal;isisestadisticcjsdeldia metro del polen evidencianquelosot,rosindividuos
.ahibndacion
as dos poblaciones son.d,ploides,ypreferenternente tetraploicles,respectivamente.l
Pdureapuedeserla ;en del ^traploide. Asi, la evidencia citologic:a apoya otros
ti
que muestran que poblacion.espuede nestarmasem]oarentadasconRpaujvercula.
OS es tas
INTRODUCTION
A
Weber and Love distributed
is
) i
T
Rocky Mountains
southern
the
t
River with scattered populations eastward in Wisconsin and Missouri (Barkley
chromosome number
1962, 1978) (Fig. tetraploid with a base of x = 23
1). It is
(Kowal Kowal
unpubl.
1975; et ms.).
al.
Apparently disjunct populations occur in Pennsylvania, Virginia, Tennes-
see, North Carolina and South Carolina (Barkleyl962, 1978, 1988; Uttal 1982;
&
Rhoads Klein 1993) (Fig. Barkley hypothesized that these are remnants of
1).
the widespread eastern migration of prairie-adapted plants during the
Hypsithermic Period of about 8000 years ago. Such populations in Montgom-
commonly
ery Virginia hybridize with P aurea, anonyma, and ohovata
Co.,
P. P.
(Uttal 1982). Because the latter three species are usually diploid with x = 22
(Kowal unpubl. widespread hybridization with would
et ms.), plattensis
al.
P.
&
be unexpected (Mahoney Kowal ms. subm.; Kowal unpubl. More-
et ms.).
al.
over, herbarium specimens from the entire range of the eastern disjunct popu-
lations are morphologically different from P plattensis of the Great Plains in
and and
their rosette cauline leaves in their smaller heads.
from North and
Individuals Carolinian Virginian populations of putative
plattensis were included in a larger study of the paupercula complex and
P.
P.
&
(Mahoney Kowal grown
allied species ms. subm.). Replicates were in a stan-
dard environment transplant garden, and data on morphology and flowering
time were analyzed by canonical discriminant analyses (CDA) and analyses
of
variance (ANOVA). Herbarium specimens complex, emphasizing
of the
dis-
its
tribution east of the Mississippi River, were studied, and a prehminary analysis
DNAs
random
of genetic similarity using amplified polymorphic (RAPDs) was
One
made. conclusion that these central Appalachian populations are best
is
included in the polymorphic P paupercula complex as P paupercula
var.
appalachiana A.M. Mahoney var nov ined. Chromosome numbers provide
criti-
evidence supporting
cal this conclusion.
AND METHODS
MATERIALS
Individuals of putative eastern disjunct Packera plattensis (P paupercula var
appalachiana) were from two The Rock Road
collected Paint population
sites.
(NC, Madison Co.: near Hot Springs, 3.2 mi northwest along Paint Rock Road
&
H wy
from Kowal Mahoney
25-70, 3120 [V/IS]) grows in loose, gravelly soil on
a steep, wooded, southwest-facing slope and road cut overlooking the French
Broad River The Leap population Montgomery mi from
Lover's (VA, 2 west
Co.:
&
McCoy
Fork on Road Kowal Mahoney
3123
Price's 652], [WIS]) consists of
[rt.
scattered clones on exposed and wooded rocky outcrops on south-facing
a bluff
New
McCoy
and
overlooking the River along the south side of road on a grav-
elly bank. Replicated individuals were randomly positioned in a standard-en-
vironment transplant garden Madison, WI.
in
m
Heads from garden were
test individuals fixed Jackson's solution (4
ethanol: 2 methanol: 2 chloroform: propionic acid: acetone, v/v), transferred
1 1
plattensis; Disjunct populat
p.
70% and Counts were made on
after about a day to ethanol, stored in a freezer
mm
young from Using squash
meiocytes of anthers florets 2.5-3.0 in length. a
m
Kowal and Kong
technique, described Beeks (1955) as modified by (1975)
anthers were prestained in aceto-carmine and squashed between a slide
(1998),
and a cover Each slide was scanned under the 40 x objective of a Zeiss
slip.
WL
Standard phase-contrast microscope, and with promising meiotic
cells fig-
ures were resquashed until their chromosomes were well-separated and in one
made
plane. Coverslips were sealed with "Zut." Counts were with the 100 x ob-
under immersion, and with well-separated chromosomes were
jective oil cells
photographed with Kodak Ektachrome 160 and Technical Pan (exposed an
at
AFM
ASA
of 100) films using a Nikon Microf lex Model photomicrographic at-
tachment (Kong 1998). Results are in Table and substantiating photographs
1
and
are in Figures 2
3.
Pamt Rock Road Madison with
Individual 9 from (NC, Co.) diploid
is
t
&
Montgomer
(Kong 1998; Figs. 2 Individual 9 from Lover's Leap (VA,
3).
tetraploid with n = 44, based on a single, but fairly good preparation (Figs. 4
is
&
A
poor anaphase from individual 10 from Lover's Leap gave an extremely
5).
I
How-
rough count of 2n = ca. 67, superficially, an approximately triploid count.
normal
ever, the regular meioses, terminating in tetrads of nuclei without
prompts
micronuclei, in this individual the interpretation that individual 10
is
Pollen diameters from the transplant garden can be used extend the
to
counts of the two individuals to their respective populations, because pollen
&
diameter correlated with polyploid (Kowal Mahoney Kowal ms.
is level 1975;
ANOVA
A
mean
subm.). nested indicates that the difference in pollen diameter
between North and
the Carolinian Virginian populations,
27.9 vs. 31.2 |Lim, is
real (Fi,8 - 24.16, p = 0.0018) and that individuals within each population do
not differ (Fsj = 2.19, p = 0.16). Taken together, this implies that the populations,
the former containing an individual with = 22 and the with = 44
n latter n ca.
ANOVAs
and
consist of all diploids all tetraploids, respectively. testing for dif
among
ferences individuals within the two populations separately give abso
no
lutely evidence (Fsj = 0.46, p = 0.80) of differences in pollen diameter (and
chromosome number)
implicitly in the "diploid" population but moderate evi
dence
(F37 = p = 0.035) in the "tetraploid" population. However, the one in-
5.11,
dividual with unusually small pollen diameter (29.0 )jm) in individual
fact,
is,
which
approximately tetraploid, so aberrancy has other causes.
10, is its
NC
among
Uttal (1982) notes that the specimens from Madison
Co., (pre-
sumably the Paint Rock Road population), he saw hybrids with anonyma.
P.
downstream
This species does occur ca. 0.5 miles from the var. appalachiana
population, and 3 of the 11 individuals collected in 1995 showed morphological
anonyma. none
similarities to Introgression here likely, but of the individu-
P. is
als in the transplant garden provided any obvious evidence of
it.
Uttal (1982) reports that aurea and paupercula appalachiana
var. (as
P. P.
McCoy
plattensis") "thoroughly introgress" along Road Individual
'T. 652).
(rt.
10 grew on the road cut and individual 9 grew nearby on the bluff's edge; the
other individuals were from less disturbed bluff Some individuals, in par-
sites.
ticular #9, have deeply pinnatif id cauline leaves with wide, distally dilated lobes
and broad, undivided terminal lobes like aurea, which rampant in an ap-
P. is
A
parent sink-hole in the woodland above the bluff. garden-grown individual
of P aurea from this site is lighter green than is typical for the species and
'
«
t-^l
^*~
i<
<•*
.V •'
!
.
*.
^
'*,
**.'.'.•
*
«...
.
:^
r
.1
= +
A, Lover's Leap, #9. Late anaphase 2n 22 ca, Fig. 5. Figure 3 retouched using Corel Pi
1,
reproduces abundantly and invasively by adventitious shoots on unlike
roots,
normal Leap
aurea. Therefore, likely that at least a portion of the Lover's
P. it is
population with
introgressed aurea.
is
P.
Chromosome
counts mdicate that Pachera plattensis does not occur in the
central Appalachians. This Great Plains species appears to be entirely tetraploid
with X = 23 and the North Carolinian population diploid with x = At
22. least
is
some members
of the Lover's Leap population in Virginia are tetraploid but
RAPDs
probably with x = 22. This evidence supports the morphological and
evidence that these central Appalachian populations are best treated as
P.
&
paupercula var appalachiana (Mahoney Kowal ms. subm.).
We UNCC
would thank GH, MO, NCU, NY, PHIL, and specimen
like to for loans,
Kiefer Kuah and Justin Lo assistance with photo scanning and retouching
for
map
(Fig. Kandis Elliot for the distribution (Fig. Dale Johnson, the staff at
5),
1),
WIS, and especially Ted Barkley for his bountiful good advice.
IEFHRENCE5
TM. A
Barkl 1962. revision of Senecu aureus l\nn .and allied specr
FY,
18-408.
65:3
Sci.
Barkley J.M. 978. Senec/o. Rogerson,,C.T,ed.Norti American
In flora,:
1
1
York Botanical Garden, 50-1
pp. 39.
among
BarkleyJ.M. 988. Variation the aureoidsene cios of North Ami
1
54:82-1
interpretation. Bot. Rev. 06.
Improvements mique
Beeks, R.M. 1955. in the squash tecf for plant
; (
3:131-133.
KoNG,V.W. 998. Putative Packeraplotte.nsis (Asteracecle: Senecioneae)
1 \r
Virginia. (Honors senior thesis, UniversityofWisc:onsin-Madison.)
Kowal, 975. Systematics of Senecicaureus and species on
R.R. illied
1 t
-c
Quebec.Mem.Torrey Club -113.
Bot. 23:1
and TM. '.UnpubLms. Chromosome
Kowal, C.C. Freeman, Barkley ni
R.R.,
Packera (Asteraceae: Senecioneae):
A.M.and KowAL.Ms.subm
Mahoney, ittedtoSida.f^acesofthePac^,
R.R.
plex (Asteraceae:Senecioneae) le upper Mid'west and southed United
in States.
t|- 1
RHOADS.A.F.and W.M.Klein, 1993.The vascular of Pennsylvania:,
Jr. flora
andatlas.Philadelphia,PA:Americai Philosophic Society
n
:al
Uttal, L.J. 982. Promiscuity of Senec/c plattensis Nijtt. in a Virginia c
1 )
344-346.