December 2012 Number 1 - Utah Native Plant Society

Utah Native Plant Society
Though A. lentiginosus var. maricopae is morphologically
distinct from its geographically closest relative, A.
lentiginosus var. wilsonii, it is not as genetically differentiated
as A. lentiginosus var. ursinus is from A. lentiginosus
var. mokiacensis (Alexander 2008, Alexander
& Liston, in prep). Alexander (2008) also found that A.
lentiginosus var. maricopae is a highly endangered endemic
(likely totaling less than 5,000 individuals primarily
due to habitat loss from suburban development)
and confined to a small region of igneous and granitic
alluvial fans in the vicinity of Scottsdale and the Verde
River drainage in northern Maricopa County, Arizona.
In this study, morphological principal coordinates
analyses (PCoA), cluster analyses, and cladistic analyses
are used to detect the degree of morphological differentiation
between Astragalus lentiginosus var. maricopae,
A. lentiginosus var. ursinus and the remaining
taxa of the Palantia and whether this differentiation corresponds
to species or varietal delimitations in preparation
for monographic revision of the A. lentiginosus
complex.
MATERIALS AND METHODS
Field observations and voucher specimens were
made from spring 2001 to summer 2004 throughout the
range of the Palantia. Most populations were visited
several times and were observed during early flower,
maturity, and senescence. Vouchers for this study are
deposited at NY, OSC, RSA, UNLV, and UVSC.
Herbarium specimens were examined at UC in December
of 1999, BRY in August of 2000, GH in August
of 2002, NY in October of 2003, and UNLV in July of
2002 and 2003. Additional herbarium specimens were
obtained on loan from BRY, CAS, DS, K, POM, RM,
and RSA.
Specimens from taxa in Astragalus Section Diphysi
were examined for two morphological PCoA studies.
The first, the 153 specimen Palantia PCoA, focused on
heavily sampling all members of the group and was designed
to evaluate the morphological distinctiveness of
A. lentiginosus var. maricopae. 103 specimens of A.
lentiginosus var. palans were used representing all major
regions of its range, including the type population.
Also included were multiple specimens of A. lentiginosus
var. bryantii (10), A. lentiginosus var. ursinus (10),
and A. lentiginosus var. wilsonii (15). Due to the poor
nature of most herbarium specimens of A. lentiginosus
var. maricopae, 5 specimens were collected in the field
in 2005 for the morphological analysis. To ensure that
the range of regional variation was present in the PCoA,
representative specimens (one except where noted) were
included from these morphologically similar and geographically
proximal varieties: A. lentiginosus var. ambiguus
Barneby (the type specimen); A. lentiginosus var.
araneosus (Sheld.) Barneby; a population of a A. lent-
iginosus (from Chloride, Mohave County, Arizona, interpreted
herein as an intermediate to A. lentiginosus
var. yuccanus M.E. Jones) considered part of A. lentiginosus
var. ambiguus in Barneby (1964); A. lentiginosus
var. iodanthus; A. lentiginosus var. mokiacensis (2 type
specimens); A. lentiginosus var. pseudiodanthus; A. lentiginosus
var. stramineus (Rydb.) Barneby (the type
specimen); A. lentiginosus var. vitreus Barneby (the
type specimen); and A. lentiginosus var. yuccanus (the
type specimen).
The second, the 43 specimen Astragalus lentiginosus
var. mokiacensis PCoA, focused on further evaluating
the morphological distinctiveness of A. lentiginosus var.
ursinus. Fifteen specimens from throughout the range
of A. lentiginosus var. ursinus were examined, including
the type specimens. For comparison, 28 specimens from
throughout the range of A. lentiginosus var. mokiacensis
(including the type specimens) were examined. Multiple
specimens and types of the synonym, A. lentiginosus
var. trumbullensis S.L. Welsh & N.D. Atwood were
included in this study. These data are a modified version
of the data used in Alexander (2005).
In both PCoA's, duplicate specimens or specimens
from the same locality were used to determine the character
states of missing data. Qualitative characters that
were found to be polymorphic within a single individual
were excluded.
The morphological matrices for both studies were
transformed into a Gower (1971) similarity matrix, a
process that is not sensitive to data sets with mixed ordinal,
nominal, continuous, and ratio data types. The matrix
was then used in the PCoA. A Kendall's tau correlation
between the PCoA axes and all morphological characters
was used to determine the magnitude of the contribution
of characters to the overall analysis (Easdale et
al. 2007, Hammer et al. 2001). All correlations and
PCoA analyses were performed using Paleontological
Statistics (PAST) version 1.76 (Hammer et al. 2001). A
Euclidean distance dendrogram was also created using
PAST for the cluster analysis.
PAUP* for Windows version 4.0 beta 10 (Swofford,
2002) was used to assess the relationships among 30
specimens of the Palantia and Section Diphysi using
cladistic methodologies.
The PCoA, cluster, and parsimony analyses were
used to address the following questions:
1) Do populations of A. lentiginosus var. maricopae and
A. lentiginosus var. ursinus form groups discrete from
the other members of the Palantia ?
2) Which morphological characters contribute to the
observed groups?
3) Are these groups morphologically differentiated from
the closely related and geographically proximal varieties
of A. lentiginosus?
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