Congruent patterns of genetic and morphological variation in the parthenogenetic lizard Aspidoscelis tesselata (Squamata, Teiidae) and the origins of color pattern classes and genotypic clones in eastern New Mexico

40 Pages·2003·4.2 MB·English

by  Taylor, Harry Leonard.

AMERICAN MUSEUM
Novitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3424, 40 pp., 14 figures, 13 tables December 9, 2003
Congruent Patterns of Genetic and Morphological
Variation in the Parthenogenetic Lizard
Aspidoscelis tesselata (Squamata: Teiidae) and the
Origins of Color Pattern Classes and Genotypic
Clones in Eastern New Mexico
HARRY L. TAYLOR,! CHARLES J. COLE,” HERBERT C. DESSAUER,*? AND
E. D. PARKER, JR.*
CONTENTS
PRD SUL ACIS phy Peateg shh Bey ion c,3 .s gsreee tise ete eID LOM FES gy opts 5 coerce IRE Ns oeR IC PAIAAIRT bP Rice oes, 3 3
INGLReerYeGsilT ahi vleMn eh, Stam tees 2, ake oa arma RAM rare Pre Solem ei i een cole LE eno EM A ete tS tata +
IMfatentals atic AMICUS Is sce he Bie fie 0 UN one ct Ths te edt i Daa eae ca ce a a S|
MorpholoniCall AmalySese +. ore .u 3.7 ey eee oa s Lee ke eaten AM eyM EM MOC uN hy 5
FICC OPNOLetio~ NAY SER a. tlw WE ge se Nae et EE re Ae le EE eee ht 2)
KarObyy p ic: Amialysis gh8 2h 2 Ae a 8 bes Bre ele els 6 ke Pee pan ews Benes eee on ele & 11
IRGSUles ATIC aI DI SCUSSIOT Es 09 je -.coeat gee eee wick reeled uae tts oh nealc hp rogetto he ln nee ot ae 11
Color Pattern Features of Pattern Classes Are Inherited Clonally .................. iBE
Karyotypes Are Gonsistent-with) Hybrid Orieair yc... stews cis + Beene ¢ srcadee etek 6 om & apdS ene te lig
Genotypic Differences Within Pattern Class C-E from Conchas Lake .............. 11
Parker‘and Selander Analyses”. . 2.4 2705 2994 . Reha Rete CR AA PR oe Bh Se 11
' Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Department of Biology,
Regis University, Denver, CO 80221. e-mail: [email protected]
? Division of Vertebrate Zoology (Herpetology), American Museum of Natural History. e-mail: [email protected]
3 Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Department of Biochem-
istry and Molecular Biology, Louisiana State University Medical Center, New Orleans, LA 70112.
4 Department of Ecology and Genetics, Aarhus University, DK 8000 Aarhus C, Denmark. e-mail: dave.parker@
biology.au.dk
Copyright © American Museum of Natural History 2003 ISSN 0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3424
IDESSaUCr Ania C Ole ANALYSES et gh oie egos eens a hte See hal hoc Py Le Bret htact eee 12
Congruence Between External Morphology and Genetic Markers in
Pattern, Class:C-E y PromeConchas Lake. State: Park. 8 i ues netelewteoniee e ils
Patterns of Variation Among Morphological Subgroups of Pattern Class C-E
and Pattern Class. D: From: Conchas’ Lake State Parks 220.6 sc seg ones eee ee ee ee oe 13
Histocompatibility Among Morphological Subgroups of Pattern Class C-E and
PARLIN EAS oe oes cac P MER NSP PRELIM EIR gowns csrs ees coe As SAY PUI Riri es seemed 16
Patterns of Morphological Variation Among Pattern Classes C, D, and E
FLOM SUMNERdkes Sake Parke nane cos ae a ee yeytiry ygR ael tate iW ute, Bie ence aes ye, 16
Comparison of Pattern Classes C, C-E, E, and E-C From Eastern New Mexico ..... 20
Situs, Ofe Pattern Clase IN ewe IVC KC ODP Bbc tang. ctt le en steer e ERE ERE Mas Mee Mae 22
Model | for Origins: Multiple Hybridizations Explain the Variation in
Aspidoscelis tesseldia’ in“ Basterm NEw. MexicO— a1..5, 1 fe 2 ee he eae oH)
Model 2 for Origins: Postformational Mutations Explain the Evolution of
ASDIAOSCelISfesseClaia INI EASteIi. NEW sMEKICO-95,5,8 ie nn tees fate be ee a eomseeerenie 6 26
Divergence, 1n.A. fesselaia trome¢Bastern New Mexico A. deat ed oe eects LES 31
Bioveooraphical (Perspechve? 3 v wes Re F cio-oacs ecocors cotety yee AS SRR) ese exiee 3 omeeares 31
MorphiolosicaliP erspectvie- jn V8 644 inde ire ec Seer es a8, (ee meee, ie,
RISES MCR PETCCSM V G ys cacy cre ree teva Eee tae nearest ae, Oe es APA ERT ee ATT eee ghg ored ge ee 33
Deficiencies. of the Pattem Class.@ aiid. BoDesitanaionss 44 iho Bi Ree sercheras es 34
FA ORORALEe VIrNpcC GASLLO inate cre yee reateger ee eter a aaa eecnrtl RPS Gene eset select ere Rls lat Rac arts See 35
Ackiledo eimwents *.: hi Oe eo bik AG er eet SE Cee AR lek LING ee nha onS R) ot 36
Thto de re alI clerk Ratha RiA et Rye MEP, pl ece~ l , 1d e aes Cant NTE ee Cr eke yin RigO ne, ve AW iid CO 36
Appendix ly Specimens Exam MNCs a eee: MA Rett hgh Rtelad octets Ot NA Races tcke wesl ok 38
2003 TAYLOR ET AL.: ASPIDOSCELIS TESSELATA
ABSTRACT
Aspidoscelis tesselata exhibits significant clonal diversity despite its recent origin (from hybrid-
ization between A. tigris marmorata and A. gularis septemvittata) and its parthenogenetic mode
of reproduction. Two hypotheses have been advanced to explain the derivation of its genetic and
morphological variation: (1) separate parthenogenetic lineages derived from several different F,
hybrid zygotes, and (2) postformational mutations occurring in a parthenogenetic lineage derived
from a single F, hybrid zygote. We evaluated these competing hypotheses with evidence from
skin transplant studies, protein electrophoresis, multivariate analyses of morphological characters,
and geographic distributions of pertinent groups. Starting with the clonal diversity at Conchas Lake
State Park, San Miguel County, New Mexico, we expanded the study to include populations at
Sumner Lake State Park and Fort Sumner (De Baca County), Puerto de Luna (Guadalupe County),
and Arroyo del Macho and Roswell (Chaves County). This enabled us to resolve origins of color
pattern classes and genotypic clones in eastern New Mexico. We used pattern class designations
C-E and E-C to signify that elements of both pattern classes were expressed in populations at
Conchas Lake and Arroyo del Macho.
The two pattern classes at Conchas Lake (C-E and D) had the same F, hybrid karyotype
(2n = 46), with haploid sets of 23 chromosomes characteristic of each progenitor species of
A. tesselata. Clonal variation was found at 4 of the 35 gene loci examined electrophoretically:
GPI (glucose-6-phosphate isomerase), EST2 (a muscle esterase), sACOH (aconitase hydra-
tase), and MPI (mannose-6-phosphate isomerase). The strong congruence between genotype
and morphological variation facilitated the characterization of three morphological subgroups
of C-E. Although these subgroups lacked individually distinctive color patterns, they were
discriminated effectively in canonical variate analyses based on scalation characters and a
priori groups of known genotype.
Nine individuals of Conchas C-E and four individuals of Conchas D have histocompatibility
data from a recent skin transplant study (Cordes and Walker, 2003). The subgroup identities
of the C-E specimens document histocompatibility among the three morphological subgroups
of C-E and between each subgroup and representatives of pattern class D. This evidence,
together with Maslin’s (1967) report of histocompatibility between pattern classes C and E,
suggests that all color pattern classes, morphological subgroups, and genotypic clones of A.
tesselata can be traced back to a single ancestral F, hybrid zygote.
A pair of pale broken lines in the middorsal region distinguishes pattern class D from the other
pattern classes. However, Conchas ID shared the GPI —100/—96, EST2 100/96 genotype with
Conchas IC-E, and individuals of these pattern classes were very similar in multivariate meristic
characters. Sumner D expressed the same type of relationship, resembling the syntopic population
of Sumner C rather than the other population of D. In addition, certain individuals of Sumner C
had partially divided (D-like) vertebral lines—additional evidence that Sumner C was ancestral to
Sumner D. We conclude that pattern class New Mexico D is polyphyletic, having originated twice
from different individuals of C-E and C in the vicinities of Conchas and Sumner Lakes.
The northern position of pattern classes C and C-E in the range of A. tesselata is consistent
with recent colonizations by individuals from more southerly populations. A candidate source
population, based on its extensive color pattern and meristic variation, is E-C at Arroyo del
Macho. The strong morphological resemblance of several northern populations to Macho E-C
rather than to either syntopic clones or geographically proximate populations of other pattern
classes supports this possibility. Evidence from geographic distributions, patterns of genotypic
and meristic variation, and histocompatibility identifies postformational mutations as the likely
basis for the genetic and morphological variation found in A. tesselata. This variation also
includes different life-history characteristics between pattern classes C and E at Sumner Lake
State Park.
The name ftesselata is presently associated indirectly with pattern class C through the neo-
type of A. tesselata. The neotype is a specimen of Colorado D, a derivative of pattern class
C. With respect to pattern classes E-C, E, and other southern variants, taxonomic restructuring
would confront mosaic patterns of genotypic, phenotypic, and geographic variation—patterns
expected from random mutations in clonally reproducing species. Aspidoscelis tesselata has
exploited a variety of ecological opportunities despite the constraints of clonal inheritance.
Postformational mutations in the generalized genotype acquired from its progenitor species
may have contributed to its ecological success.
+ AMERICAN MUSEUM NOVITATES NO. 3424
INTRODUCTION selata is ecologically successful based on a
geographic range that includes parts of Chi-
Reeder et al. (2002) presented evidence
huahua, Mexico (Zweifel, 1965), Texas (Dix-
that North American lizards previously as-
on, 2000), New Mexico (Degenhardt et al.,
signed to the genus Cnemidophorus repre-
1996), Oklahoma (Webb, 1970), and Colo-
sent a monophyletic group, leaving South
rado (Hammerson, 1999), and its presence in
American species in possession of the ge-
various assemblages of bisexual and parthe-
neric name in a separate clade. This neces-
nogenetic congeners (Cuellar, 1979; Taylor et
sitated resurrecting the generic name Aspi-
al., 2000, 2001). Based on its extensive lat-
doscelis for North American species. There-
itudinal distribution, Aspidoscelis tesselata
fore, the present paper involves an interpre-
might have inherited an advantageous gen-
tation of the evolutionary history of the
eralized genotype from its two progenitor
diploid parthenogenetic species Aspidoscelis
species (Taylor et al., 2001). This ecological
tesselata in eastern New Mexico, the species
success has occurred despite the absence of
formerly allocated to Cnemidophorus tesse-
genetic recombination. Price (1992) and
latus.
Price et al. (1993) provide a contrasting in-
Aspidoscelis tesselata is an excellent spe-
terpretation of “‘success”’ in A. tesselata.
cies for assessing the evolutionary potential
Morphological variation in A. tesselata in-
of a parthenogenetic vertebrate. Its attributes
cludes four color pattern classes (Zweifel,
include a broad latitudinal distribution, well-
1965; Taylor et al., 1996) integrated into the
marked genotypic and phenotypic variation,
currently understood phylogenetic history of
and histocompatibility evidence that evolu-
A. tesselata by Walker et al. (1997a). Anoth-
tionary divergence began with a single basal er diploid pattern class (F), included in A.
parthenogenetic individual (Maslin, 1967;
tesselata by Zweifel (1965), was described
Cordes and Walker, 2003). Of additional evo- as A. dixoni by Scudday (1973), and Dens-
lutionary interest, Aspidoscelis tesselata par- more et al. (1989) presented mitochondrial
ticipated in the origin of a new species. Al- DNA evidence that A. dixoni and A. tesselata
though hybridization between A. tesselata may have originated from independent hy-
and A. figris marmorata produced sterile bridizations.
triploid hybrids (Taylor et al., 2001), the trip- Color pattern differences among pattern
loid species A. neotesselata (Walker et al.,
classes C, Colorado D, New Mexico D, and
1997a) originated from an A. tesselata X A.
E were used to discover local examples of
sexlineata hybridization (Parker and Selan- ecological (Walker et al., 1997b) and life-his-
der, 1976; Densmore et al., 1989; Dessauer tory (Taylor et al., 1997, 2000) differences
and Cole, 1989). Equally intriguing is the between sympatric clones. However, we ex-
possibility that a new parthenogenetic spe- pose (below) complications in using color
cies could result from genetic changes (di- pattern classes C and E as simple descriptors
vergence) in an established parthenogenetic of regional patterns of geographic variation.
species (Echelle, 1990; Taylor and Cooley, Our study is rooted in the important pio-
1995a, 1995b; Manriquez-Mordn et al., neering investigations of Zweifel (1965),
2000; Schmitz et al., 2001). In addition to Maslin (1967), Parker and Selander (1976),
this possibility, we investigated the origin of and Parker (1979). Zweifel (1965) set the
color pattern classes and the pattern of di- stage for future research by recognizing that
vergence that has occurred in A. tesselata a few color pattern classes could accommo-
from eastern New Mexico. date the previously undecipherable morpho-
Aspidoscelis tesselata originated recently logical variation in A. tesselata. He was then
(Densmore et al., 1989; Reeder et al., 2002) able to describe A. tesselata from Conchas
from hybridization between a female A. tigris Lake as comprising two color pattern classes
marmorata and a male A. gularis septemvit- (C and D) and document the remarkable me-
tata (Neaves, 1969; Parker and Selander, ristic variation in Conchas C. The magnitude
1976; Dessauer and Cole, 1989; Dessauer et of this morphological variation was unex-
al., 1996). Despite its clonal pattern of in- pected because it challenged the intuitive ex-
heritance (Dessauer and Cole, 1986), A. tes- pectation that parthenogenetic reproduction
2003 TAYLOR ET AL.: ASPIDOSCELIS TESSELATA S,
constrains phenotypic variability. With great criminant functions of 1.308 for L-breaks,
acuity, Zweifel (1965) predicted that Con- —0.519 for DL-breaks, and —0.380 for PV-
chas C might consist of several clones, and breaks, classified 26 of 100 specimens of
electrophoretic analyses of proteins by Park- Conchas “‘C”? as Macho “E”’ and 14 of 37
er and Selander (1976) confirmed this pre- specimens of Macho “E”’ as Conchas “‘C’’.
diction. Parker (1979) then demonstrated Despite misclassified individuals and a weak
congruence between meristic and genotypic eigenvalue (0.113), the two groups differed
variation, thereby providing genetic markers significantly in discriminant function scores
(clones IC, VIC, and VIIIC) for morpholog- (t135 = —3.912; P < 0.0005). Therefore, we
ical subgroups of Conchas C. These clones used two new pattern class designations: C-E
appeared to have combinations of alleles that for the Conchas Lake non-Ds, and E-C for
were polymorphic in their bisexual ancestors. the form at Arroyo del Macho. The first letter
Therefore, Parker and Selander (1976), Park- signifies the pattern class identity of this pop-
er (1979), and Parker et al. (1989) argued ulation in previous studies; the second letter
that several independent hybridizations were emphasizes that this population contains a
responsible for the genetic and morphologi- range of color pattern variation that includes
cal variation in Conchas C. However, Maslin individuals with color pattern features of this
(1967) revealed histocompatibility between second pattern class. Additional evidence of
pattern classes C and E, implying that the color pattern ambiguities in these two groups
genealogies of different pattern classes con- is presented in other sections of the paper.
verged on a single parthenogenetic progeni- With the addition of two new color pattern
tor. designations, our study was based on five
The purpose of the present study was to color pattern classes of A. tesselata from six
(1) reconcile patterns of genotypic and mor- localities. The focal samples comprised pat-
phological variation for clones of A. tesselata tern classes C-E (N = 135) and D (N = 51)
at Conchas Lake and different color pattern from Conchas Lake State Park (fig. 1). These
classes from eastern New Mexico, (2) reas- samples included 34 specimens (21 C-E, 13
sess the multiple hybridization hypothesis to D) with protein phenotypes identified elec-
explain variation among these groups, (3) trophoretically by Parker and Selander
evaluate evidence that the genetic and mor- (1976) and H.C.D. and C.J.C. (this study)
phological variation in A. tesselata was gen- and 13 specimens (9 C-E, 4 D) used in skin
erated by postformational mutation, and (4) transplant experiments by Cordes and Walker
determine if divergent clones deserve formal (2003). Two additional groups of samples
taxonomic recognition. were included to determine patterns of evo-
lutionary divergence. The first group con-
MATERIALS AND METHODS sisted of pattern classes E and E-C with elec-
trophoretic data from Fort Sumner (N = 11),
MORPHOLOGICAL ANALYSES
Roswell (NV = 10), and Arroyo del Macho (NV
In a departure from all previous studies, = 10). The second group comprised samples
we use new pattern class designations to flag lacking electrophoretic data. These were (1)
color pattern ambiguities in A. tesselata at pattern class C (N = 47), pattern class E (NV
Conchas Lake State Park and Arroyo del Ma- = 47), and pattern class D (N = 5) from
cho. The results of a discriminant analysis Sumner Lake State Park (approximately 90
(DA) justified two pattern class designations. linear km south of the Conchas Lake locali-
Using Zweifel’s (1965) pattern class desig- ties), (2) pattern class E (N = 25) from
nations, the DA model was based on samples Puerto de Luna (approximately 34 linear km
of pattern class “‘C”’ from Conchas Lake and northwest of the Sumner Lake collecting
pattern class “‘E”’ from Arroyo del Macho as sites), (3) pattern class E (N = 5) from Fort
the a priori groups (fig. 1). These specimens Sumner (approximately 18 linear km south-
met body size criteria (see below) that re- east of Sumner Lake), and (4) pattern class
moved ontogenetic variation from the three E-C (N = 31) from Arroyo del Macho (ap-
color pattern characters used in the DA (table proximately 105 linear km south of Sumner
1). The DA model, with standardized dis- Lake). The geographic relationships of sam-
6 AMERICAN MUSEUM NOVITATES NO. 3424
ee ele eae SE
fe é
Sa SRN ERY & ON
~
¥ic
=aI
Bte
S
SieSes eiee
Fig. 1. Geographic relationships among four northern collecting localities of Aspidoscelis tesselata
of color pattern classes C, New Mexico D, and E and convenience classes C-E and E-C. Color patterns
found at the four sites are (1) Conchas Lake State Park: C-E and New Mexico D; (2) Sumner Lake
State Park: C, New Mexico D, and E; (3) Puerto de Luna: E; and (4) Arroyo del Macho: E-C.
2003 TAYLOR ET AL.: ASPIDOSCELIS TESSELATA 7
TABLE 1
Meristic Characters (and SVL) Used in Analyses of Morphological Variation in
Aspidoscelis tesselata from the Locations Studied
Character
abbreviation Description
GAB Number of granular dorsal scales in a single row around midbody. There are eight longitudinal rows of
enlarged scales making up the ventral body surface. The third ventral row on either side of the mid-
sagittal line terminates anteriorly in the axillary region. The 15th ventral scale posterior to this terminus
established the point for beginning the GAB count.
COS Bilateral total of circumorbital scales as standardized by Wright and Lowe (1967).
LSG Sum of lateral supraocular granules on both sides of the head. These granular scales are located between
the supraoculars and superciliary scales, and the count includes all scales anterior to the suture line
between the third and fourth supraoculars.
FP Sum of femoral pores on both thighs.
GS Number of granular gular scales bordering the medial edges of the eight anterior sublabials (four on each
side, or their subdivisions) and the posterior mental.
PSC Sum of all scales, including occipitals, contacting the outer perimeter of parietal and interparietal scales.
L-breaks Total number of interruptions by black pigment of the lateral pale stripes.
DL-breaks Total number of interruptions by black pigment of the dorsolateral pale stripes.
PV-breaks Total number of interruptions by black pigment of the paravertebral pale stripes.
SDL-T4 Number of subdigital lamellae on the fourth toe of one foot (right was chosen unless damaged).
SVL Length of body from tip of snout to posterior edge of preanal scales (in mm).
pling localities are shown in figure 1, and cause certain individuals in critical samples
specific information on samples and sam- (those with protein phenotypes and those
pling localities is provided in appendix 1. used for skin transplants) had damaged or
We shortened frequent references to geno- missing 4th toes on both feet.
typic clones (GPI and EST2 loci) and affili- Body length (snout—vent length = SVL)
ated pattern class as follows: Conchas IC-E was measured to the nearest millimeter with
(Roman numerals indicate that the genotype digital calipers. Significant relationships
is known) and 1C-E (Arabic numerals refer were found between color pattern characters
to morphological subgroups corresponding to and SVL in composite samples of pattern
a priori groups of known genotype); VIC-E classes C and C-E (N = 173) and E and E-C
and 6C-E; VHIC-E and 8C-E. We also com- (N = 112). These relationships were between
bined abbreviated names of collecting local- L-breaks and SVL in C + C-E (P = 0.003)
ities and pattern class designations to refer to and between L-breaks and SVL (P = 0.016)
various groups (Conchas D; Sumner C, D, and PV-breaks and SVL (P = 0.001) in E +
and E; Luna E; Macho E-C). E-C. Using specimens >66 mm SVL for pat-
Each specimen was scored for 10 meristic tern classes C, C-E, and D and >69 mm SVL
characters representing seven scalation fea- for pattern classes E and E-C removed on-
tures and three color pattern features (tables togenetic variation from the definitive sam-
1, 2), the latter involving the number of ples (P = 0.08 and P = 0.62 for the regres-
breaks (disruptions by transverse black bars) sions of L-breaks on SVL, and P = 0.18 for
in the lateral, dorsolateral, and paravertebral the regression of PV-breaks on SVL).
pale stripes. A traditional character (SDL-T4 Three morphological subgroups of pattern
in tables 1 and 2) was omitted from multi- class C-E were identified from a canonical
variate analyses to maintain consistency and variate analysis (CVA) of 21 individuals of
comparability across different color pattern known genotype, using the three GPI, EST2
classes, genotypic clones, and morphological genotypes as a priori groups. These sub-
subgroups. We excluded this character be- groups, corresponding to genotypic clones,
AMERICAN MUSEUM NOVITATES NO. 3424
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2003 TAYLOR ET AL.: ASPIDOSCELIS TESSELATA 9
were then used as a priori groups to assign ELECTROPHORETIC ANALYSES
individuals of C-E lacking electrophoretic
data to morphological subgroup. The pattern Two of the 21 presumptive protein loci as-
sayed with horizontal starch gel electropho-
of meristic variation among the morpholog-
ical subgroups was then depicted by a defin- resis by Parker and Selander (1976), Pgi (=
itive CVA, with subgroup assignments used GPI, glucose-6-phosphate isomerase) and
to define a priori groups. The same procedure Est-2 (= EST2, a muscle esterase), and 4 of
was used to assign the skin transplant spec- the 31 presumptive protein loci assayed by
H.C.D. and C.J.C. (GPI, EST2, aconitase hy-
imens of Cordes and Walker (2003) to mor-
phological subgroup and show their patterns dratase [SACOH], and mannose-6-phosphate
of variation. isomerase [MPI]) revealed clonal differences
Nine meristic characters (table 1) were in the Conchas Lake samples. Parker and Se-
used in most analyses. Exceptions included lander (1976) designated alleles at each locus
CVAs based only on color pattern characters according to migration of their allozymes rel-
and those used for skin transplant specimens. ative to the most common allele (“‘100”’ for
anodally migrating proteins and “‘—100” for
We excluded characters based on DL-breaks
cathodally migrating proteins) found in A. ti-
and PV-breaks from the latter because the
dorsolateral and paravertebral stripes had gris marmorata. Clonal designations from
been used as transplantation sites, and the in- Parker (1979) use a combination of multilo-
tegrity of the pattern was compromised in cus electrophoretic genotype (Roman numer-
these specimens. Only specimens with com- als I-XIII) and pattern class (B = A. neotes-
plete data were included in each analysis. selata; C, D, and E = A tesselata; F = A.
Specific procedures are detailed in the appro- dixoni). All available specimens of pattern
priate sections of Results and Discussion. classes C (= C-E here) and D analyzed by
To facilitate comparisons, a symmetric dis- Parker and Selander (1976) and Parker
similarity matrix of Mahalanobis distances (1979) were rescored for meristic characters
(D’) between group means was used to con- and combined with AMNH specimens with
struct an additive tree depicting the morpho- known GPI and EST2 genotypes from Con-
logical similarities and differences among the chas Lake to represent the foundation for the
various groups. The D? values were obtained present study: 10 individuals of clone IC-E
from BMDP program 5M, Linear and Qua- (GPI —100/—96, EST2 100/96), 7 individu-
dratic Discriminant Analysis, accessed via als of clone VIC-E (GPI —99/—96, EST2
SYSTAT 10.2. Additive trees are directed 100/96), 4 individuals of clone VUIC-E (GPI
graphs with paths (sums of horizontal branch —100/—96, EST2 96/96), and 10 individuals
lengths) representing relative distances be- of clone ID (GPI —100/—96, EST2 100/96).
tween entities. This procedure, in conjunc- Unfortunately, the three individuals of clone
tion with ordination (de Queiroz and Good, VIIC (GPI —99/—96, EST2 96/96) described
1997), is more appropriate than hierarchical by Parker (1979) have been lost and were
clustering for illustrating patterns of diver- thus unavailable for reanalysis.
gence from similarity/dissimilarity data (Sat- New electrophoretic data for 31 gene loci
tath and Tversky, 1977; Wilkinson et al., have been provided by H.C.D. and C.J.C.
1996; de Queiroz, 1998). For example, intra- (table 3), based on more recently collected
cluster branches (representing specific AMNH specimens (see appendix 1). These
groups) can vary in length on an additive tree loci include 17 of the 21 analyzed by Parker
but not on trees generated by hierarchical and Selander (1976). Methodology followed
joining techniques. Therefore, additive trees Harris and Hopkinson (1976), Murphy et al.
provide information on differences among (1996), and, particularly for North American
intracluster groups in addition to intercluster lizards of the genus Aspidoscelis, Dessauer
groups. Additive trees are not intended as et al. (2000). For each locus, alleles are des-
phylogenetic reconstructions, but clonal di- ignated in alphabetical order according to de-
vergence manifested in quantitative meristic creasing anodal migration of their allozymes.
differences should be evident. For multilocus enzymes, loci are listed nu-
10 AMERICAN MUSEUM NOVITATES NO. 3424
TABLE 3
Genotypes at 31 Gene Loci* in Clones? of Aspidoscelis tesselata of Pattern Classes C—E and D
from Conchas Lake State Park Compared with Pattern Class E-—C from Arroyo del Macho
(See Taylor et al., 2001.)
TESC-E TESC-E TESC-E TESD TESE-C
Locus (N = 3) (N = 2) (N = 2) (N = 2) (N = 11)
Oxidoreductases
ADH ab ab ab ab ab
G3PDH aa aa aa aa aa
IDDH aa aa aa aa aa
LDHI1 ab ab ab ab ab
LDH2 aa aa aa aa aa
sMDH ab ab ab ab ab
mMDH aa aa aa aa aa
sMDHP ab ab ab ab ab
sIDH bb bb bb bb bb
mIDH aa aa aa aa aa
sSOD ab ab ab ab ab
mSOD aa aa aa aa aa
Transferases
sAAT ab ab ab ab ab
mAAT ab ab ab ab ab
CK1 aa aa aa aa aa
AK aa aa aa aa aa
Hydrolases
ESTD bb bb bb bb bb
EST2¢ be be bc be be
PEPA cd cd cd cd cd
PEPB bb bb bb bb bb
PEPD cc cc cc cc cc
PEPE aa aa aa aa aa
ADA ac ac ac ac ac
Lyase
sACOH ac be be be be
Isomerases
MPI ac ac ab ac ab
GPlIe ac ac ab ac ac
PGM2 ab ab ab ab ab
PGM3 ab ab ab ab ab
Blood proteins
TFe bb bb bb bb bb
ALB ab ab ab ab ab
HB aa aa aa aa aa
4Abbreviations for loci are as follows: ADH, alcohol dehydrogenase; G3PDH, glycerol-3-phosphate dehydrogenase; IDDH,
L-iditol dehydrogenase; LDH, L-lactate dehydrogenase; MDH, malate dehydrogenase; MDHP, malate enzyme; IDH, isocitrate dehy-
drogenase; SOD, superoxide dismutase; AAT, aspartate aminotransferase; CK, creatine kinase; AK, adenylate kinase; EST, esterase;
PEP, peptidase; ADA, adenosine deaminase; ACOH, aconitase hydratase; MPI, mannose-6-phosphate isomerase; GPI, glucose-6-
phosphate isomerase; PGM, phosphoglucomutase; TF, transferrin; ALB, albumin; and HB, hemoglobin; s, cytosolic enzyme; m,
mitochondrial enzyme. For loci at which no a- or b-allele is shown, these occurred in other samples or in closely related taxa that
are not included in this paper.
bDistinctive alleles (not found in pattern class E-C) that characterize different clones of pattern classes C-E and D are in an
enlarged, boldface type and involve only three loci: sACOH, MPI, and GPI.
©This table consists of new data determined by H.C.D. and C.J.C. For EST2, all lizards were heterozygotes, thus consistent with
the common clone designated by Parker and Selander (1976) and Parker (1979) as 100/96. For GPI, the ac genotype is the same
as the common clone designated as — 100/—96 for Pgi by Parker and Selander (1976) and Parker (1979), whereas our ab geno-
type is their —99/—96 genotype. As we only recently recognized the subtle differences in GPI, the ac genotype we report here is
the same as the ab genotype reported by Taylor et al. (2001).