SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM LANATUM AND E. CONFERTIFLORUM VAR. CONFERTIFLORUM (ASTERACEAE)

2007·9.3 MB·English

by  John S Mooring

Madrono, Vol. 54, No. 1, pp. 30-41, 2007
SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM LANATUM AND
E. CONEERTIELORUM YAR. CONEERTIELORUM (ASTERACEAE)
John Mooring
S.
Biology Department, Santa Clara University, Santa Clara, CA, 95053
[email protected]
Abstract
i
Chromosomes in excess ofthe basic complement have been known for 100 years. Nevertheless, in
most species the role ofsupernumerary or B chromosomes remains unknown or speculative. Here, I
describe the frequency, distribution, and transmission to progeny ofsupernumerary chromosomes in
two widely distributed western North American polyploid complexes. Meiotic analyses of
microsporocytes found one to four supernumerary chromosomes in 14% of the 293 populations
examinedinEriophyllinnlauatimu and one, two,orsixsupernumerariesin 15% ofthe 133 populations
examined in E. confertiflonou var. confertiflonim. Most supernumerary chromosomes were in the size
range of A chromosomes, indistinguishable from As, and did not pair with them. Artificial
hybridizations showed that the supernumerary chromosomes were transmitted by either parent.
Populations with supernumerary chromosomes were nonrandomly distributed in both species.
Intervarietal or interspecific hybridization may be responsible for some of their nonrandom
distribution in E. lamitum. Supernumerary chromosomes may be involved in the dysploid i
chromosome numbers in EriophyUum. .
Key Words: Asteraceae, dysploidy, EriophyUum, polyploid complex, supernumerary chromosome
distribution, supernumerary chromosome frequency, and supernumerary chromosome transmission.
Wilson (1925, pp. 872-878) referred to chro- studied. Adaptive effects ofsupernumerary chro-
mosomes in excess of the basic complement as mosomes are known or surmised; for example,
''supernumerary.'' He distinguished between Bosemark's (1956) study of Festuca pratensis
those that arose by nondisjunction and others Hudson found a correlation between the clay
derived by fragmentation. Chromosomes in content ofthe soil in most Swedish provinces and '
excess of the basic 'A" complement that do not the frequency of accessory chromosomes. The
pair with A chromosomes and have certain other number of species reported to carry these extra ;
characteristics are more often referred to as "B" chromosomes has increased sharply in the last
rather than ''supernumerary" or "accessory" 50 yr; about 2000 are known in many taxonomic
chromosomes. Chromosomes in excess of the groups of animals and flowering plants (see
basic complement are generally smaller than the Palestis et al. 2004).
A chromosomes, do not pair with them but can
pair with each other, and often are more Background ofPresent Study
heterochromatic than the A chromosoines (Soltis
1983). EriophyUum lanatum (Pursh) Forbes and E.
The number of supernumerary chromosomes confertiflorum (DC.) A. Gray are polyploid \
may vary in the same plant, e.g., Poa trivicilis complexes (Mooring 1975, 1994, 2001). Eriophyl-
L.(Bosemark 1957) or in different plants of the lum lanatum is a short-lived, woody-based, \
same population, e.g., Xanthisma texammi DC herbaceous perennial; E. confertiflorum var. i
!
(Semple 1974). In Clarkia imguiculcita Lindley, confertiflorum is a subshrub. Both are highly
the frequency of individuals with supernumerar- self-incompatible. EriophyUum lanatum is widely
ies varied from 0 to 79% in different populations, distributed in western North America from 5 to
and, in one population, varied significantly in 3500 m; E. confertiflorum var. confertiflorum
different years (Mooring 1960). occurs from central California to adjacent Baja
In some species, supernumerary chromosomes California from 5 to 3000 m.
I
can be transmitted or increased in number, as in Artificial hybridizations show barriers to in-
several grass species (e.g., Festuca anmdinaceci terbreeding in both species complexes. Those in j
Schreber[Bosemark 1957], or in Clarkia uuguicu- E. confertiflorum var. confertiflorum are weaker; j
lata [Mooring I960]). Rosato et al. (1996) consequently, the races are harder to delimit
reported that the transmission ofB chromosomes (Mooring 1994). Interbreeding barriers in E.
in wild races ofmaize was under genetic control. lanatum are stronger; the 10 "varieties" of E. \
Whether these extra chromosomes are geneti- lanatum are geographic subspecies (Mooring \
\
cally inert, parasitic, or ofsome adaptive value is 2001). Artificial hybrids have been obtained |
unclear, and may well depend on the species between E. confertijlorum var. confertiflorum %
2007] MOORING: SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM 31
and all varieties ofE. lanatum (Mooring2001 and in ''UC Mix" soil in an unheated Santa Clara
unpublished). Natural hybrids between E. lana- University greenhouse.
tum and E. confertiflorum var. confertiflonim are
infrequently encountered (Constance 1937; Meiotic Analyses
Mooring 1994). Eriophyllum latilohum Rydb.
may be a product ofsuch interspecific hybridiza- Young capitula were fixed in 1:3 acetic ethanol
tion (Constance 1937; Munz 1959). or, rarely, in 1:3:6 acetic-chloroform-ethanol.
My report is an offshoot of long-term bio- Quickly putting collections in the refrigerator or
systematic studies ofEriophyllum lanatum (Moor- an ice-filled cooler usually improved fixation
ing 1975, 2001) and E. confertiflorum (Mooring (Anderson 1996). Beek's (1955) technique often
1994). Those studies focused on the distribution provided clearer preparations. Most meiotic
of cytotypes and on barriers to interbreeding at analyses were of diakinesis or first metaphase
the diploid level. The supernumerary chromo- stages of microsporocytes squashed in acetocar-
somes in both species presented interesting mine and examined with a phase contrast
problems, but time and space requirements microscope. Squashing anthers in 1% aceto-
prevented further study. orcein instead of aceto-carmine often resulted in
The supernumerary chromosomes ofEriophyl- more darkly stained chromosomes. Voucher
lum lanatum and of E. confertiflorum var. specimens have been deposited in the Santa Clara
University Herbarium (SACL).
confertijlorum are in the size range ofthe smaller
members of the basic complement. They do not In this study, chromosomes in excess of the
seem to differ from the A chromosomes in basic complement ofEriophyllum lanatum and E.
appearance or behavior. With one apparent confertiflorum var. confertiflorum are called su-
exception, they do not pair with an A chromo- pernumerary chromosomes rather than B chro-
some. Thus, they resemble the supernumerary mosomes or accessory chromosomes. Because the
chromosomes ofClarkia unguiculata (Lewis 1951; Eriophyllum supernumerary chromosomes were
Mooring 1960). Lewis (1951) believed that these morphologically indistinguishable from the chro-
extra chromosomes originated as trisomies. mosome of the basic complement ("A'' chromo-
aryThechdriostmroisboutmieosn,anedspferceiqaulelnycyinofEs.upelrannuamteurm,- Asomaensd)sautpemerinousmies,raIrydicdhnrootmodsisotmiensguiisnhrebpeotrwteienng
suggest an adaptive role or meiotic drive, or meiotic configurations. The letter 'T" is used to
both. Artificial hybridizations have shown that refer to an unpaired chromosome. Fragment
supernumeraries could be transmitted, but have chromosomes were also present, and are called
fragment chromosomes.
not documented the frequency of transmittal
(Mooring 2001).
Artificial Hybridizations
Thus, in 2000, I began reciprocal crosses in E.
lanatum: 8 II X 8 II + one supernumerary All hybridizations were performed in a pollina-
chromosome and 8 II X 8 II + two supernumer- tor-free greenhouse. The plants were separated by
ary chromosomes. I present my findings about at least 30 cm. Capitula were rubbed together
both species in one report because the species are over 2-8 d.
closely related and the results of each study are
similar. The purpose ofthis paper is to report the Pollen Fertility Estimates
frequency, geographic distribution, and trans-
mission of supernumerary chromosomes in E. Fresh pollen grains were stained overnight in
lanatum, E. confertiflorum var. confertiflorum, cotton blue-lactophenol. Estimates rest on
and their putative hybrid derivatives. 300 grains per sample. Each plant was sampled
on two different days.
Materials and Methods
Results
Species
Viability of Plants with
Supernumerary Chromosomes
Most of the plants used in this study were
grown from fruits collected from natural popula- Plants with supernumerary chromosomes
tions; a few were transplants from these popula- could be detected only by meiotic analysis. Pollen
tions. The location of the Eriophyllum lanatum fertility varied widely in plants with and without
and E. confertiflorum var. confertiflorum natural extrachromosomes, but no significant differences
populations are given in Mooring (2001) and were found.
Mooring (1994), respectively.
Number of Supernumerary Chromosomes
Treatments per Plant
Fruits were germinated in vermiculite or in I found one to four supernumerary chromo-
vermiculite-soil mixtures. Seedlings were potted somes in Eriophyllum lanatum; and one, two, or
MADRONO
32 [Vol. 54
six supernumerary chromosomes in E. conferti- hallii, lanceolatum, and obovatum (Table 1). The
flonmi var. coufertiflorunn and two in E. latilo- frequency of supernumeraries in diploid, tetra- j'
hunu a putative E. Icmatimi X E. confertiflorum ploid, hexaploid, and octoploid plants of E.
var. confertiflonun hybrid (Tables 1 and 2). lanatum was, respectively, 13% (41/328), 10%
(10/103), 0% (0/16), and 18% (2/11). Tetraploids
Meiotic Configurations with supernumerary chromosomes appeared lim-
ited to vars. achillaeoides and leucophyllum, and
In E. lauatimu diploids not derived from octoploids with supernumerary chromosomes to
artificial hybridizations, one plant formed 8 II + var. integrifoUum (Table 1).
oaIthIcerihsni.amsTomhsate m7riacItIrhoe+srpo1trIhoIcaIyntceossnt,fiicgakunyrdatc7ihorInIo,m+iofs1douImIeeIsti,on v3a4rT%iheedfofarrmeiqonundeginvciypdouoapflussluaptaienordnnsu3m1ear%nadrfyovarcrhipertooipemusol,astofimroeonsms jI
suggests that in this instance a supernumerary in var. lanatum to 4% and 7% in var. arachnoi-
can pair with A chromosomes. In all other such deum.
diploids, those with one supernumerary formed 8
tIIhe+ I1 Id.iIvnidaedfewatcelflisrstscomreetdapahsahsaev,inagn8dII9++1 I9, FrequEe.nccyonofferStuifpleorrnuummvearra.rcyonCfherrtoimfloosroummes in
separations occurred in first anaphase cells. \
Conspicuously lagging chromosomes in first or The overall frequency of plants and popula-
second division were rare. Most plants with two tions with supernumerary chromosomes was 13%
supernumeraries formed 8II + 2Ior9II. The (24/180) and 15% (20/133), respectively. One
single plant with 19 chromosomes formed 9 II -I- 1 plant had a fragment chromosome; the rest had
I. One of the two plants with 20 chromosomes normal-sized supernumerary chromosomes. The
formed 10 II exclusively, the other variously 10 frequency of supernumerary chromosomes in
II, 9 II + 2 I, and, in a few cells, 8 II + I IV diploid, tetraploid, hexaploid and octoploid ',
(Table 1). populations was, respectively, 9%(6/69), 22%
In contrast to diploids not derived from (13/60), 0% (0/1), and 0% (0/2). One population !
artificial hybridizations, those derived from {143) was mixed, having a diploid with two
artificial hybridizations often formed variable supernumeraries and two tetraploids with none
meiotic configurations (Table 3). Notable among (Table 2). Only 39% of the diploid populations
crosses producing progeny with variable meiotic had supernumeraries, compared to 74% in E.
configurations was Cross 7 in Table 4 between an lanatum. '
8 II + 1 I seed parent and an 8 II pollen parent. It
produced two progeny with variable meiotic
configurations. One formed 8 II + 1 I or 7 II + Supernumerary Chromosomes in Putative E.
3 I; the other formed 8 II + 1 I, 8 II + 2 I , 7 II + 3 confertiflorum var. confertiflorum X E. \I
I, and 7 II + 4 I. Icmatum derivatives i
In E. laiiatum tetraploids, plants with one
supernumerary formed 16 II + 1 I; those with two Eriophyllum latilobum consists of two popula-
supernumeraries 16 II +2 I or 17 II, orexclusively tions along San Mateo Creek in San Mateo
17 II (Table 1). County, California. Individuals formed 16 II
In E. confertiflorimi var. confertiflorum, di- except for one that formed 16 II + 2 I. The other
ploids formed 8 II + 1 I ifone supernumerary was putative E. confertiflorum var. confertiflorum X
present. One plant with two supernumeraries E. Icmatum hybrids were tetraploids and hexa- j
consistently formed 9 II. Other plants with more ploids with one or two supernumerary chromo-
than one supernumerary formed 8II + 2or3I. somes, forming 16 II + 1 I, 17 II, 24 II + 1 I, or 25 :
Tetraploids formed 16 II + 1 I if one supernu- II. The frequency of individuals and of popula-
merary was present but invariably or frequently tions with supernumerary chromosomes was,
fsioxrTwmheeerdesi1np7grleIeIseipnfltatnw(tToaobwfleerE.e2)lp.raetsielnoth,wnanwdith19sIuIpewrhneun- 4rpe0osppukelcmattiviseotlnryis,pw2ien4r%eSaranensdtMrai5ct0te%ed.otTaohneadnpauadtpjapatrcieovnxetimhSayatbnertliayd jj\\
meraries formed 16 II + 2 I. Clara Counties, California (Table 2).
I
Frequency of Supernumerary Chromosomes in Transmission of Supernumerary Chromosomes
\
E. lanatwn in Artificial Intervarietal and Interspecific Hy-
bridizations in E. lanatum and E. confertiflorum |
The overall frequency of plants and popula- var. confertiflorum j
tions with supernumerary chromosomes was 12% i
(54/459) and 14% (42/293), respectively. Super- The chromosome number of 13 of the 30
\
numerary chromosomes were not found in the parents in 17 hybridizations (Table 3) was
,
total of 42 plants examined in vars. croceum. known; the other parents were assumed to form
;
ill
2007] MOORING: SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM 33
8 II because representatives of the parental Crosses 1-3, and both parents are known in
populations formed 8 II. The crosses in Table 3 Crosses 4-7. Transmission of one or two
are divided into four sections and are numbered supernumerary chromosomes occurred in five of
to facilitate describing the results. Supernumer- the six progeny in Cross and in 7 of 10 progeny
1,
ary chromosomes were transmitted in all in Cross 2. In Cross 3, the chromosome number
crosses. of the pollen parent is not known, and the
In Section 1, wherethechromosome numberof population that furnished it had plants that
both parents was known, transmission of one formed 8 II + 1 I as well as 8 II. If the pollen
supernumerary failed in one of the parents in parent formed 8 II, the supernumerary in the seed
Cross 1. One supernumerary was transmitted by parent was transmitted to 9 of the 17 progeny,
the seed parent in Cross 2 and by the pollen and multiplied in one of them. A fragment
parent in Cross 3. chromosome was also transmitted to three other
In Section 2, where thechromosome numberof plants, probably from the pollen parent. Crosses
the seed parent was known, and transmission was 4 and 5 were reciprocal; the supernumerary
through the seed parent, two supernumeraries in chromosome was transmitted when S338-4 was
Cross 4 and one in Cross 5. In Crosses 6 and 7, the seed parent but not when it was the pollen
transmission probably occurred through the parent. However, failure of transmittal through
pollen parent, because the seed parent formed 8 the pollen may be a matter of chance; the
II, and supernumeraries had been observed in progeny consisted of only two plants. Crosses 6
populations 204 and 205 from which the pollen
and 7 are reciprocal. Transmission through the
parents came (Table 1). The origin of supernu- pollen parent occurred in 7 of the 18 progeny
meraries in Cross 8 was uncertain. The seed
(39%), compared to 9 of the 14 progeny (64%)
parent formed 8 II, and although supernumerar-
for the seed parent.
ies were not observed in the pollen parent
population {38), the single plant examined in Pollen fertility figures for progeny with and
the progeny formed 8 II + 1 I or 7 II + 3 I. without supernumeraries did not differ signifi-
In Section 3, (chromosome number of pollen cantly (Table 4).
parent known) the results paralleled those in
Section 2. Transmission was through the pollen
parent in Crosses 9 and 10, two supernumeraries Nonrandom Geographic Distribution of
in Cross 9 and one in Cross 10. In Cross 11, the E. lanatum Populations with
fragment and supernumerary probably came Supernumerary Chromosomes
from the seed parent, SI84-1, because supernu-
Six regions had one to five populations with
TmehrearsioeusrcoecocfurtrheedsuipnePronpuumleartairoynin18C4ro(sTsab1l2ewa1)s. a high frequency of supernumerary chromo-
unknown because supernumeraries were not somes. Along the Snake River in Idaho and
found in the parental populations. Oregon, 11 of the 16 plants in five diploid var.
In Section 4, chromosome numbers were lanatum populations had one or two supernu-
unknown forthe parents. Presumably the parents meraries. In Trinity County, California, each of
formed 8 II as in their parental populations. The three diploid var. grandiflorum populations was
source or sources of the supernumeraries in the represented by a plant with two supernumerary
progenieswasnot known (Table 3). All but Cross chromosomes. In Colusa and Lake Counties,
15 were either interspecific or intervarietal, and California, two diploid and two tetraploid var.
were often between geographically distant popu- achillioides populations were represented by
lations. single plants with one supernumerary or one
fragment chromosome. In southwestern Oregon
(Jackson, Josephine, and Douglas Counties), four
Frequency ofTransmission ofE. lanatum
Supernumerary Chromosomes in of the six plants in tetraploid var. achillioides
Artificial Hybridizations Populations 335 and (52, and var. leucophyllum
Populations 18 and 337 had one or two
In pre-2000 hybridizations, how frequently supernumerary chromosomes. Also, all four
supernumeraries were transmitted was unknown plants in diploid Population 338, an achillioides-
because usually only one plant per cross was leucophyllum intermediate, had one or two
analyzed (Table 3). Attempts to use reciprocal supernumeraries. Two diploid populations of
crosses to estimate transmission frequencies were var. integrifolium had high frequencies of plants
only partly successful because low percentage bearing supernumerary chromosomes. In Adams
germination or failure to flower resulted in only County, Washington, four of five plants in
two offive combinations being reciprocal. Population 265 had one to three extra chromo-
The crosses in Table 4 are numbered to somes. In Elko County, Nevada, each of the
facilitate describing the results. The meiotic single plants in Populations250 and251 had four
configuration of the seed parent is known in extra chromosomes (Table 1).
))
MADRONO
34 [Vol. 54
Table 1. Supernumerary Chromosomes in Eriophyllum lanatum Populations. Locations within
counties are approximate. An asterisk indicates that a univalent was seen to divide at Metaphase 1, two
asterisks that 9 + 9 disjunctions were seen to occur. The numbers following a taxon name show, respectively, the
frequency ofindividuals and populations with supernumeraries.
Number ofplants
Meiotic With that
Taxa/Location Population configuration configuration Analyzed
Var. achillioides
(8/85 = 9%; 8/61 = 13%)
i^A, LaKe <^o.. izu 8 II + fragment 1 11
Kelseyville
LaKe v^o., i_iear LaKC IZ/ o8 T1I14+- 11 T1, 7/ 1T1T+-u 11 1T1TT1 1 11
Siskiyou Co., Dorris I1I1I1 o8 T1T1 -+1- 11 T1** 11 Z.
Colusa Co., Leesville JOJ 11A0. T1T1 _+L 11 1T 1 11
1JZ, 16 TT -1- 1 T 1 11
onasia v^o., ran Kiver IJJ 1lAo T1T1 _+i_ z0 1T or^rr 117/1T1T 1 11
ivinis
OR, Jackson Co., JJJ 117/ T1T1 11 .
Central Point
Josephine Co., Selma Al 11A0 1T1T +-1- 11 1T 11 11
Total 8 (89%) 9
Var. urachnoideutn
/(1^/1^2A4 — 4Av07o, 11//11/14 — 1/0/7c)\
v^A^, oan iviaieo i„o.. Jul O8 1TT1 +-L 11 1T 1oiai 1 [^J\J/o z
Woodside
Var. cvoceiiin
(U/14, yJ/O)
Var. grandifloirum
(j/oy — DVC, j/j/ — Vv<?)
CA, Calaveras Co., /O QO 1T1T -+L 11 T1 7
Murphy's
El Dorado Co., J/V yQ T11T or^rr OQ 1T1T +_L Z7 T1 11
Diamond Springs
Trinity Co., Trinity 174 9 II or 8 II + 2 I 1 1
Center
Trinity Center Qy T11T 11
Trinity Center 221 Oo T11T +1 z") T1 o^r^ yn 1T1T 11
1oiai J {OJ/c o
Var. haliu
(0/3; 0/1)
Var. integrifolium
C(IAD,/IMUUon—olCovoe.,, 1Sjo/nooUra— zzvo) 1111/41 8O T1T1 +1 I1T1 11 z
Pass Summit
ID, tslaine Co., Ketchum ZD/ 8O T1T1 +1 11 T1 z
Custer Co., Stanley ZjO OQ 1T1T +_i_ 11 1T J z
Owyhee Co., Riddle 252 8 II + 1 I 1
NV, Elko Co., Elko 250 10 II 1
Elko Co, Mountain 251 10 II, 9 II + 2 I,
City 8 II + 1 IV in a few
cells 1
OR, Deschutes Co., La 108 8 II + 1 I 1
Pine
Wheeler Co., Antone 271 8 II + 2 I 1
WA, Adams Co., 265 8 II + 1 I or 9 II 5
Ritzville 8 11+ 1 I to7 II+3 I
8 II + 1 I
9 II + 1 I
WY, Fremont Co., 56 8 II + 1 I 1
Dubois
Teton Co., Moran 55 8 II + 1 I 1
OR, Wasco Co., The 104 32 II + 1 I 1
Dalles
2007] MOORING: SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM 35
Table Continued.
1.
Number ofplants
Meiotic With that
Taxa/Location Population configuration configuration Analyzed
WA, Klickitat Co., The 102 33 II 1
Dalles Dam
Total 16 (80%) 20
Var. lanatiim
(11/32 = 34%; 5/16 = 31%)
ID, Idaho Co., Harpster 30 8 II + 2 I 1
Washington Co., 204 8 II + 1 I 3
Beggs 8 II + 2 I
Washington Co., 325 8 II + 2 I 4
Brownlee Dam 8 II+2 I to 7 II+4 I
OR, Baker Co., Oxbow 205 8 II + 1 I 3
Dam
Oxbow Dam 324 8 II + 2 I 5
8 II + 1 I
Total 11 (69%) 16
Var. lanceolatiim
(0/12; 0/8)
Var. leucophyllum
(6/37 = 16%; 6/29 = 21%)
OR, Douglas Co., Glide 18 16 II + 1 I 1
Douglas Co., Azalea 337 16 II + 2 I 1
Marion Co., Silverton 94 8 II + 2 I or 9 II 1
Multnomah Co., 355 8 II + 2 II* 1
Shepperd's Dell
WA, Cowlitz Co., 172 9 II or 8 II + 2 I 1
Kalama River
San Juan Co., Orcas 239 8 II + 1 I 1
Island
Total 6 (67%)
Var. ohovatum
(0/13; 0/7)
INTERGRADES BETWEEN VARIETIES
(7/50 = 14%; 4/34 = 12%)
Var. achillioides-yar. arachnoideum
(1/12 = 8%; 1/9 = 11%)
CA, Napa Co., St. 229 17 II
Helena
Var. achillioides-yar. grandiflorum
(1/17 = 6%; 1/11 = 9%)
CA, Glenn Co., 195 17 II or 16 II + 2 I
Stonyford
Var. achillioides-\ar. leucophyllum
(4/5 = 80%; 1/2 = 50%)
OREGON, Douglas 338 1 I
Co., Dillard 2 I or 9
Var. amchnoideum-\ar. grandiflovum
(0/2; 0/2)
Var. grandiflorum-integvifolium
(1/3 = 33%; 1/2 = 50%)
CA, Nevada Co., 332 16 II + 1 I
Emigrant Gap
Var. grandiflorum-\2iV. lanceolatum
(0/1; 0/1)
Var. integnfoliunt-\ar. lanatum
(0/10; 0/7)
TOTAL: (54/459 = 12%; 42/293 = 14%)
MADRONO
36 [Vol. 54
Table 2. Supernumerary Chromosomes in Populations of Eriophyllum confertiflorum Var.
CONFERTIFLORUM, E. LATILOBUAf, AND PUTATIVE ERIOPHYLLUM CONFERTIFLORUM VAR. CONFERTIFLORUM X
E. LANATUM Hybrid Derivatives. Regional and county names are bolded. Locations within counties are
approximate. An asterisk indicates that a univalent was seen to divide at Metaphase 1. The numbers followingthe
taxon name show, respectively, the frequency ofindividuals and populations with supernumerary chromosomes.
The numbers following a county name show the frequency ofpopulations with supernumeraries. Counties, all in
California, are arranged in north to south order, as are populations in them. Percentages are rounded.
Number ofplants
Location Population Meiotic configuration with that configuration Analyzed
Eriophyllum confertiflorum var. confertiflorum (24/180 = 13%; 20/133 = 15%)
South Coast Ranges
Alameda (1/4), Arroyo 16 16 II + 1 I
Mocho
San Mateo (3/7), 143 8 II + 2 I*
Hillsborough
Montebello Ridge 22 16 II + 1 I
Portola State Park 142 17 II, 16 II + 2 I
Santa Clara (3/15), Loma 10 16 II + 2 I
Prieta
Loma Prieta 11 17 II
Mt. Hamilton 18 16 II + 1 I
Monterey (4/13), Del 7 16 II + 1 I
Monte
Carmel Valley 25 17 II
19 II
Big Sur 107 8 II + 1 I 1
Lucia 36 16 II + 1 I 2
San Benito (1/10), 136 17 II 1
Pinnacles N. M.
Total 14 (70%) 20
Transverse Ranges
Santa Barbara (2/9), 67 16 II + 1 I 1 2
Lompoc
New Cuyama 150 17 II 2 3
Total 3 (60%) 5
Peninsular Ranges
San Diego (2/8), 61 9 II 1
Escondido
Vista 147 8 II + 1 I 1
Total 2 (67%)
Sierra Nevada
Calaveras (1/1), 85 16 II + 1 I 1
Mokelumne
Mariposa (1/8), El Portal 127 8 II 1 I 1
Tulare (1/5), Mineral 79 8 II 3 I 1
King Road
Kern (1/9), Wofford 77 8 II + 1 fragment 1
Heights
77 8 II + 2 I 1
Total 5 (100%)
Eriophyllum latilohum (1/9 11%; 1/2 = 50%)
San Mateo, San Mateo 16 II + 2 I 1 (33%)
Creek dam
Putative natural hybrids, E. lanatum var. arachnoideum X E. confertiflorum var. confertiflorum (6/25 = 24%; 4/8
50%)
San Mateo, Alpine Road 9 16 II + 1-2 I 1
Black Mountain 1 24 II + 1 I 2
25 II 1
Borel Hill 11 17 II 1
Santa Clara, Montebello 6 25 II 1
Ridge
Total 6 (43%)
2007] MOORING: SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM 37
Nonrandom distribution ofE. confertiflorum var. between the two varieties (Mooring 2001).
confertijlorum Tetraploid Populations with Artificial hybridizations between diploids show
Supernumerary Chromosomes that barriers to interbreeding are low. Mean
percentage pollen fertility of integrifolium X
Although the overall ratio ofE. confertiflorum lanatum progeny was 60 ± 23% (Mooring 2001,
var. confertijlorum diploid to tetraploid popula- Table 7).
tions was 69 to 60, tetraploid populations with The var. grancliflorum populations in Trinity
supernumeraries outnumbered diploid ones 13 to County, California, are in a region where vars.
6. That ratio rose to 8 to 2 in Monterey, Santa achillioides, grandiflorum, and lanceolatum meet;
Clara, and San Mateo Counties, California. Only some populations there are intermediate. Diploid
two populations with supernumeraries were progenies from artificial achillioides X grand-
wfeoruenddispoluoitdhs oofnlSyan1t6akBmarabpaarrat, CionunStayn. DTiheegyo iifflloorruumm, XachlialnlcieooidleastumX hylbarnicdeiolzaattuimo,nsahnadvegrmaenadn-
County (Table 2). pollen fertilities of, respectively, 57 ± 18%, 66 ±
16%, and 68 ± 16% (Mooring 2001, Table 7).
Discussion Similarly, the var. achillioides cluster in Lake
and Colusa Counties, Cahfornia, occurs where
Frequency of Supernumerary Chromosomes vars. achillioides, arachnoideum, and grandiflorum
Probably Underestimated merge. Intergrades are numerous (Mooring
2001). Diploid progenies from vars. achillioides
I examined only one or two plants in most X arachnoideum, achillioides X grandiflorum, and
populations. Larger samples likely would have arachnoideum X grandiflorum artificial hybridiza-
shown more populations with supernumeraries tions had, respectively, pollen fertilities of 74 ±
and different frequencies of supernumeraries in 8%, 57 ± 18%, and 51 ± 16% (Mooring 2001,
the populations. Table 7).
Varieties achillioides and leucophyllum are
Hypotheses for Presence of Supernumerary sympatric in southwestern Oregon. (Variety
Chromosomes in E. lanatum achillioides populations in northern California
and southwestern Oregon differ markedly from
Various hypotheses have been proposed to the southern populations. Variety ternatum
account for supernumerary chromosomes in Greene has been proposed to recognize them.)
other species, including adaptive value and Differentiating between var. achillioides (possibly
meiotic drive that could perpetuate extra chro- also var. ternatum) and var. leucophyllum be-
mosomes even if they had deleterious effects. I comes difficult or impossible, notably in Douglas
haveno informationabout E. lanatum thatwould County, Oregon. Artificial hybridizations be-
support or discount adaptive value or meiotic tween Douglas County Population 338 and two
drive. Supernumerary chromosomes, however, var. leucophyllum populations produced diploid
can be transmitted in E. lanatum varieties progenies whose mean pollen fertility was 78% ±
(Table 3, 4). Also, artificial hybridizations of 16 and 81% ± 13 (Mooring, unpublished).
diploids representing vars. achillioides, grand-
iflorum, integrifolium, and lanatum show that
barriers to interbreeding are comparatively low Hypotheses for Nonrandom Distribution of
(Mooring 2001, Table 7). E. confertiflorum var. confertiflorum Tetraploid
Natural hybridization between chromosomally Populations with Supernumerary Chromosomes
differentiated populations could lead to gametes
with extra chromosomes. The meiotic configura- At least three hypotheses can be made for the
tions in the progenies of Crosses 8, 16, and 17 nonrandom distribution ofE. confertiflorum var.
(Table 3) suggest chromosomal restructuring confertijlorum tetraploid populations with super-
accompanied by the presence of supernumerary numerary chromosomes, especially those in
chromosomes. Chromosomal restructuring is Monterey, Santa Clara, and San Mateo Counties
evident from many other artificial hybridizations (Table 2): 1) supernumerary chromosomes are
between diploids in E. lanatum (Mooring 2001). adaptive, 2) meiotic drive exists, and 3) local
Except for the Elko County, Nevada, var. climatic or edaphic conditions affect meiosis and
integrifolium population, all others with a high thereby lead to gametes with extra chromosomes.
frequency of supernumerary chromosomes oc- These hypotheses are not mutually exclusive.
curred where different varieties meet. The Adams Two other explanations peculiar to polyploids
County, Washington, var. integrifolium popula- are: 1) tetraploids tolerate supernumeraries better
tion is adjacent to var. lanatum populations. than diploids, and 2) some plants described as
Variety integrifolium populations surround the having supernumerary chromosomes may be
var. lanatum populations along the Snake River. aneuploids generated by neopolyploids (see
Oregon has diploid populations intermediate Ramsey and Schemske 2002, pp. 601-607).
MADRONO
38 [Vol. 54
Table 3. Artificial Intervarietaland Interspecific Hybridizationsin EriophyllumlanatumandE.
CONFERTIFLORUM VAR. CONFERTIFLORUM THAT PRODUCED PROGENY WITH SUPERNUMERARY CHROMOSOMES.
Seed parent is listed first. Only one plant in each progeny was examined meiotically. Each of the 17 crosses is
numbered. Bolded chromosomecounts are those known for the parent, unbolded those known forthepopulation
that furnished it.
Parental taxa and location Parents Meiotic configuration
SECTION CHROMOSOME NUMBER OF BOTH PARENTS KNOWN
1.
Eriophyllum confertiflorwu var.
confertiflorimi X E. lanatum
var. lanatum, CALIFORNIA,
Mariposa X OREGON, Baker
1. Eagle Peak X Oxbow Dam S127-2 (8 11 + 1 I) X S324-7 (8 II + 1 I) 8 II + 1 I
Eriophyllum confertiflorum var.
confertiflorwu X E. lanatwyi var.
croceum, CALIFORNIA,
Mariposa X Fresno
2. Eagle Peak X Badger SI27-2 (8 II + 1 I) X S309-22 (8 II) 8 II + 1 I to 6 II + 5 I
Eriophyllum lanatum var. obovatum
X var. lanatunu CALIFORNIA,
San Bernardino x OREGON,
Baker
3. Running Springs X Oxbow Dam S289-14 (8 II) X S324-3 (8 II + 1 I) 8 II + 1 I
(I frequently divides at
Ml)
SECTION CHROMOSOME NUMBER OF SEED PARENT KNOWN
2.
Eriophyllum lanatum var. integrifolium
X var. arachnoicleum,
WASHINGTON, Adams X
CALIFORNIA, Mendocino
4. Ritzville X Elk S265-4A (8 II + 2 I) X S212-I (8 II) 9 II, occasional 8 II + 2 I
Eriophyllum confertiflorum var.
confertiflorimi X E. confertiflorum
var. confertiflorum CALIFORNIA,
Mariposa X Santa Cruz
5. Eagle Peak X Bonny Doon SI27-2 (8 II + 1 I) X 20 (8 II) 8 II + 1 I
Eriophyllum lanatum var. achillioides
X var. lanatunu CALIFORNIA,
Yolo, X IDAHO, Washington
6. Winters x Brownlee Dam S150-2 (8 II) X S204-3 (8 II, 8 II + 1 8 II + 1 I
or 2 I)
Eriophyllum lanatum var. integrifolium
X var. lanatum, OREGON, Union
X OREGON, Baker
7. Elgin X Oxbow S267-33 (8 II) X S205-34 (8 II, 8 II + 1 I
8 II + 1 I)
Eriophyllum lanatum var. lanceolatum
X var. achillioides, CALIFORNIA,
Humboldt x CALIFORNIA,
Santa Clara
S8.ESClaTtIeOCNreekCXHLRoOmMaOPSriOetMa E NUMBER O28F0-P3O(L8LIIE)NXP38A-R11EN(8TIIK)NOWN 8 II + 1 I, 7 II + 3 I
3.
Eriophvllum lanatum var. integrifolium
X var. lanatum, WYOMING,
Yellowstone National Park X IDAHO,
Washington
9. Tower Junction X Brownlee Dam S58-1 (8 II) X S204-1 (8 II + 2 I) 8 II + 2 I or 9 II
Eriophyllum lanatum var. araclmoideum
X Eriophvllum confertiflorum var.
confertiflorum, CALIFORNIA,
Mendocino X Los Angeles
10. Elk X Vincent S212-1 (8 II) X S74-4B (8 II + 1 I) 8 II + 1 I
Eriophyllum lanatum var. grandifloruni
X var. grandifloruni, CALIFORNIA,
Trinity X CALIFORNIA, El Dorado
11. Trinity Center X Coloma SI84-1 (8 II) X S187-2 (8 II) 8 II + 1 I + 1 fragment
2007] MOORING: SUPERNUMERARY CHROMOSOMES IN ERIOPHYLLUM 39
Table 3. Continued.
Parental taxa and location Parents Meiotic configuration
EriophvUum /anaturn var. arachnoideum
X var. leucophyUimu CALIFORNIA,
San Mateo X OREGON, Multnomah
S12E.CWToIodOsNideCXHSRheOppMeOrdS^sODMeEllNUMBER OF NE3I3T0-H1ER(8PIIA)RXESN3T55K-4NO(8WINI), THAT8OIIF+P1AIRENTAL
4.
POPULATION KNOWN
EriophvUum kmatimi var. achillioides
X var. hallii. CALIFORNIA,
Santa Barbara X CALIFORNIA,
Contra Costa
13. Mt Diablo X New Cuyama S306sih (8 II) X S7-3 (8 II) II + 1 I
Eriophyllum lanatum var. arachnoideum
X var. obovatum, CALIFORNIA,
San Mateo X CALIFORNIA, Kern
14. Woodside X Greenhorn Summit 330-2 (8 II) X 322-17 (811) II + 1 fragment
EriophvUum confertiflorum var. confertijlorum
X EriophyUum confertiflorum var.
confertiflorum, CALIFORNIA,
San Diego X Santa Cruz
15. San Diego X Bonny Doon S120-1 (8 II) X 20 (8 II) 8 II + 1 fragment
EriophyUum lanatum var. integrifolium
X var. integrifolium, WYOMING,
Yellowstone National Park X IDAHO,
Boise
16. Tower Junction X Banks S58-4 (8 II) X S158-8 (811) 8 II+ 1 I, occasional 6 II
+ 1 IV + 1 I
Eriophyllum lanatum var. grandiflorum
X var. leucophvllum, CALIFORNIA,
Tehama X WASHINGTON, Island
17. Payne's Creek X Deception Pass S199-12 (8 II) X 237-1 (8 II) 6 II + 4 I most frequent,
also 8 II, 7 II + 2 I, I
sometimes divides, 7
II + 3 I, 6 II + 5 I, 5 II
+ 1 III + 1 I
Supernumerary Chromosomes and Dysploidy involved in the formation of the dysploid series.
Supernumerary chromosomes might have be-
In Eriophyllum, as presently constituted, base come members of the A complement, especially
chromosome numbers are ^ = 4, 5, and 7 for the ifthey are trisomies. Alternatively, extra chromo-
annual species and n = ^ for the perennial somes might be obtained by interspecific hybri-
species. Two annual species have extra chromo- dizations. Lewis (1953) suggested that ascending
somes. Counts for E. wallacei are 5 II + 0-1 I dysploidy {x = 7, 8, and 9) in Clarkia may have
(Taylor 1967; Strother 1972, 1976; Johnson involved the acquisition of supernumerary chro-
1978), and 5 II + 0-3 B chromosomes (Johnson mosomes or the occurrence of interspecific
1978). Counts for E. pringleiare 7 II + 0-1 centric hybridizations. Lewis and Roberts (1956) de-
fragment (Strother 1972, 1976), 8 II (Keil and scribed the origin of Clarkia lingulata {n = 9)
Pinkava 1976), 7 II + 0-1 I and 7 II + 0-3 B from C. biloba(^7 = 8) bytheaddition ofa tertiary
chromosomes (Johnson 1978). Supernumerary trisomic.
chromosomes are also present in the perennial It is interesting that base haploid chromosome
eriophyllums. Eriophyllum Icmatum has one to numbers in the closely related genera Eriophyl-
four supernumerary chromosomes; E. conferti- lum, Syntrichopappus, and Pseudobahia (Baldwin
florum var. confertiflorum has one, two, or six and Wessa 2000) form the dysploid series 8-7-6-5-
supernumerary chromosomes. 4-3. Perhaps significantly, P. heermannii (Dur-
Grant (1981, pp. 358-360) referred to a base and) Rydb. has three base haploid chromosome
haploid chromosome number series of8-7-( )-4-3 numbers and chromosomes in excess ofthe basic
in Eriophyllum and Pseudobahia as an example of complement, 2/7 = 6+0-2 I, 2/z = 8 +0-1 I or0-1
"descending aneuploidy" derived by unequal B, and In = 10 + 0-1 I (Johnson 2006). For the
reciprocal translocations. (The symbol ( ) indi- past three years, I have been maintained an
cates missing intermediate numbers.) However, artificial hybridization program in Pseudobahia
supernumerarychromosomes may also have been heermcmni to analyze meiosis, detect barriers to