ANNUAL LIPID CYCLES IN THE LIZARD CNEMIDOPHORUS TIGRIS

APPROVED:

Major ^/ofessor

XUII TlX Director of the Department of Biology

or Graduate School

Gaffney, Fred G, Annual lipid cycles in the lizard

Cnemidophorus tigris« Master of Arts (Biology), August,

1972, 42 pp., 5 tables, 11 figures, bibliography, 43 titles.

Annual lipid cycles were determined for adult male and

female Cnemidophorus tigris collected near El Paso, Texas

during 1970-1971. In whiptails, most lipids are stored In

the carcass, tail, and post-coelomic fat bodies. Females

had greater total lipid reserves than males in most col-

lections. Fat body and carcass lipids appear to be used by

males for maintenance during brumation (— winter dormancy

from September to May) and by females for maintenance and

vitellogensis during brumation. Although reduction of lipid

reserves in the carcass during brumation was not significantly-

different between sexes: females, as a result of vitello-

genesis, used significantly more fat body lipids than males

during brumation. Males replaced all lipid reserves depleted

during brumation by July while females showed no significant

change. Females significantly depleted fat body and carcass

lipid reserves from July to early August, probably for the

production of the second annual clutch of eggs. Immediately

after the deposition of the second clutch in August, there was

a trend for females to rapidly increase lipid reserves in prep-

aration for brumation in late August. Liver lipid levels were

significantly greater in females than males collected in late

August. Results from field collections of adult C. tigris

indicate that major seasonal activity is from mid—May

to late August; testes size is cyclic and maximal size of

testes coincides with observed mating; females laid two

clutches of eggs; and the overall ratio of males to females

in collections was 3 J 2. Different microhabitat preferences

and size of home range contributed to biased ratios in the

collections.

ANNUAL LIPID CYCLES IN THE LIZARD CNEMIDOPHORUS TIGRIS

THESIS

Presented to the Graduate Council of the

North Texas State University in Partial

Fulfillment of the Requirements

For the Degree of

MASTER OF ARTS

By

Fred G. Gaffney, B. S,

Denton, Texas

August, 1972

TABLE OF CONTENTS

ABSTRACT , iii

LIST OF TABLES . vi

LIST OF ILLUSTRATIONS . . . . . . vii

Chapter Page

I. INTRODUCTION 1

II. METHODS AND MATERIALS 3

Description of Study Area Field Collections Reproductive Cycles Lipid Extraction Procedure Statistical Treatment

III. RESULTS 7

Field Collections Reproductive Cycles Lipid Cycles

IV. DISCUSSION 13

Field Collections Reproductive Cycles Lipid Cycles Acknowledgements

APPENDIX 22

LITERATURE CITED . . . . . 39

LIST OF TABLES

Table Page

1. Average monthly air temperatures in El Paso, Texas during 1970 23

2. Number of male and female Cnemidophorus tigris collected in El Paso during 1970-1971 24

3. Monthly variations in collection sites of male and female Cnemidophorus tigris 2 5

4. Mean - standard deviation of snout-vent length; lean carcass tissue: dry weight of lipids,to-tal tissue, and percent lipids for fat bodies, liver, ova, carcass and total tissue for monthly samples of male and female Cnemi-dophorus tigris. . . . . . 26

5. Mean i standard deviation of snout-vent length; lean carcass tissue; dry weight of lipids, to-, tal tissue, and percent lipids for fat bodies, liver, ova, carcass and total tissue for monthly samples of female Cnemidophorus tigris placed in three ova size classes. . . . 27

vx

LIST OF ILLUSTRATIONS

Figure Page

1. Monthly variations in size of testes for Cnemidophorus tigris 28

2. Monthly variations in size of follicles for Cnemidophorus tigris 29

3. Monthly variations in weight of lean carcass tissue in male and female Cnemidophorus tigris 30

4. Monthly variations in weights of lean carcass tissue in female Cnemidophorus tigris placed in three ova size classes . 31

5. Monthly variations in percentage of fat body lipids for male and female Cnemidophorus tigris. 32

6. Monthly variations in percentage of fat body lipids for female Cnemidophorus tigris placed in three ova size classes 33

7. Monthly variations in percentage of liver lipids for male and female Cnemidophorus tigris 34

8. Monthly variations in percentage of carcass lipids for male and female Cnemidophorus tigris. . . . . . . . . . . . . . 35

9. Monthly variations in percentage of carcass lipids for female Cnemidophorus tigris placed in three ova size classes 36

10. Monthly variations in percentage of total lipids for male and female Cnemidophorus tigris. . . . . . . . . 37

11. Monthly variations in percentage of total lipids for female Cnemidophorus tigris placed in three ova size classes . . . . . . . . . . 38

Vll

CHAPTER I

INTRODUCTION

The whiptail lizard, Cnemidophorus tigris, is conspic-

uous and abundant in desert and semi-arid communities from

southern Idaho to northern Mexico (Pianka, 1970) . Whiptails,

characteristically, are active only in the late spring and

summer months, and hibernate during the remainder of the year.

The length of this activity period is greater in the southern

than northern parts of its geographic range (Pianka, 1970) .

In West Texas, adults are active 3 -4 months per year (Hoddenbach,

1965)« Hoddenbach (1965) suggested that brumation (=winter

dormancy in ectothermic vertebrates, Mayhew, I965) for 8-9

months per year may be a physiological adaptation which re-

duces the effects of predation, starvation and inclement

weather.

Maintenance during brumation without food for 8 -9 months

should require utilization of a considerable amount of fat

reserves. However, Hoddenbach (I965) reported that sizes of

fat bodies did not change significantly during brumation in

C. tigris. I find it difficult to believe that C. tigris can

fast for 8 -9 months without using some energy reserves. Per-

haps lipids stored in the carcass or elsewhere are used by

C. tigris for maintenance during brumation. In many lizards,

fat also is stored in the carcass and tail (Avery, 1970; Clark,

1970) and has been reported to be used during brumation (Avery,

1970: Dessauer, 1955)•

Although numerous ecological studies have been made on

C. tigris (Echternacht, 1967? Hoddenbach, 1965; Medica, 1967;

Milstead, 1957a, 1957b, 1965; Pianka, 1970) inadequate quan-

titative data are available concerning the use of its lipid

reserves. Therefore, my objectives were to examine lipid

levels quantitatively in several possible storage sites (i.e.,

livers,post-coelomic fat bodies, and carcasses) in adult liz-

ards collected throughout the year; determine if there are

any differences in lipid levels between males and females;

determine the amounts of lipids used during brumation by males

and females; and determine the amount of lipids used by females

for reproduction.

CHAPTER II

METHODS AND MATERIALS

Description of Study Area,

The study area was in a tract of Chihuahuan Desert

located near the northeast city limits of El Paso, Texas

(latitude 31° 55'N; longitude 106° 23'W; elevation 3918 ft.).

The area around El Paso is characterized by mild winters and

hot summers. Table 1 shows the monthly mean air temperatures

recorded in El Paso during 1970. Summer temperatures usually

exceed 90 F during the day whereas daily winter temperatures

are usually below 60 F. Most of the annual 7.5 inches of rain

falls between July and September. High wind velocities (>45

MPH) are common during each month.

The dominant plant, mesquite (Prosopis .julif lora) . was

found in association with small aeolian mounds which are

separated by large open areas of loose igneous derived sand

and limestone (Shreve, 1942). Other conspicuous plants in-

clude ratany (Krameria parvifolia). sagebrush (Artemesia

filifolia). and catclaw (Mimosa biuncifera) .

Field Collections

Whiptails were collected from 15 August 1970 to 20

August 1971 during the first of their two peaks of their daily

activity (930-1200 and 1600-1830 hr MST). Several methods

were used to capture lizards: pit falls traps, grape blow-

guns, and 22 caliber dust shot. The last method was most

efficient, but head wounds were necessary so as not to damage

fat bodies and reproductive organs. Wounds to the hind legs

or abdomen were usually not fatal and the lizard would escape

into the nearest pack-rat (Neotona sp.) hole. Captured liz-

ards were tagged, placed in plastic bags, and kept on ice in

a styrofoam container to prevent tissue deterioration until

they could be frozen and stored without chemical preservation

in the laboratory.

Reproductive Cycles

The reproductive cycle was studied by examining changes

in the gonads of males and females during the year. Males

and females were considered mature if they were a72 mm snout-

vent length (SVL) (Hoddenbach, I965). The sex of each lizard

was determined by internal examination of the gonads. The

left testis was measured (length + width in mm) in all adult

males. These measurements were grouped by month of collection

for comparison with similar data reported by Hoddenbach (1965),

Follicles with yolk (diameter in mm) and oviducal eggs (length

and width in mm) were measured in all adult females. Females

were also examined for expanded oviduct which indicated they

were recently spent. Results of the presence or absence of

follicles with yolk and oviducal eggs in conjunction with ex-

panded oviducts were used to elucidate the reproductive cycle

of females.

Lipid Extraction Procedure

Lipid levels of liver, fat bodies, and carcass were

determined monthly for samples of adult male and female C.

tigris. A modified Folch et al. (1957) technique was used

to extract lipids from fat bodies, ova, livers, and carcasses

of 73 females and 57 males. Carcasses (minus fat bodies,

livers, gonads, and digestive tracts)were homogenized with a

minimal amount of distilled water in a two-speed Waring

Micro-blendor for one minute. Other tissues were homogenized

in a Potter-Elenhjnor tissue grinder for approximately two

minutes. Homogenized tissues were transferred to Erlenmeyer

flasks using a minimal amount of distilled water and 20 ml

of chloroform.-«methanol ( 2 : 1 , V/V) were added to the flasks

per gram of tissue (wet weight). After the contents of the

flasks were agitated on a two-speed Eberbach shaker at low

speed for one hour, they were transfered to a separatory

funnel and enough distilled water was added to establish the

8:4:3 (chloroform:methanol:water) ratio necessary to insure

proper separation (Folch et al., 1957)• The contents of the

separatory funnel formed a bi-phasic system when allowed to

separate for 12 hours at room temperature. The lower layer

of the bi-phasic system was pure dissolved lipids and chloro-

form. This layer was separated into a tared aluminum container,

vacuum desiccated to remove the chloroform, and weighed to

the nearest 0.1 mg. This value represented dry weight of lipids,

The tissue-methanol-water layer was poured into a tared beaker,

vacuum desiccated to remove the methanol and water, and

weighed to the nearest 0.1 mg. This value represented the

dry weight of lean tissue.

Statistical Treatment

All C. tigris collected during a month, were pooled by

sex for statistical treatment. Females were placed into three

ova size classes (OSC) to examine the relationship between

reproductive condition and lipid levels in various tissues

(Fitzpatrick, 1970). Adult females without follicular de-

velopment (henceforth non-reproductive) were placed in OSC

1; females with yolking follicles in OSC 2; and females with

oviducal eggs in OSC 3•

The percentage of lipid in each tissue was calculated

as dry weight of lipids/total dry weight of tissue X 100.

Dry weights of lipids/dry weights of lean carcass tissue X

100 was used to compare individual lipid levels for the sep-

arate tissues of each lizard. All percentage data were

angular-transformed prior to statistical analysis (Sokal and

Rohlf, 1969). Single-factor analysis of variance (AN0VA)

was used to test the effect of time (month) on tissue lipid

levels of males and females. Differences among the means

were tested with a Duncan's 5% New Multiple Range Test (NMRT)

(Steele and Torrie, i960).

CHAPTER I I I

RESULTS

Field Collections

Age and sex of C. tigris collected from 15 August 1970

to 20 August 1971 are given in Table 2. Most of these liz-

ards were adults. Dr. Walter Whitford (per. com.) reported

that adult whiptails entered brumation in El Paso before the

first week of September 1970. The presence of only first

year juveniles in my collections on 11 and 12 October 1970

indicates that adults began brumation before juveniles.

According to Whitford, all juveniles entered brumation before

the last week of October 1970 and did not emerge from brumation

until the first week of April 1971. I made an intensive but

unsuccessful search for brumating lizards between 18 December

1970 and 14 January 1971. Early spring collections (April)

contained only juveniles. The first adults were captured

on 15 May 1971.

The unbalanced ratio of adult males to females (3 : 2)

found in the collections was not observed in juveniles (Table

2). In order to test the hypothesis that the unbalanced sex

ratios derive from a collection bias which results from adult

males and females occupying different microhabitats, the

exact site where each lizard was first sighted was recorded

during 1971. C. tigris were either encountered on mesquite

8

mounds or in the open areas between mounds. If the lizards were

first sighted in open areas, whether foraging or running to

avoid capture, they were classified as being in the open; and

if found only on one mesquite mound and would not leave the

mound to escape capture, they were classified as being on a

mound. Approximately equal numbers of males (adults and juveniles)

were observed in open areas as were observed on mounds (Table 3).

However, almost twice as many females (adults and juveniles) were

first sighted on mounds as were sighted in open areas (Table 3)«

Reproductive Cycles

Monthly variations in the size of testes for C. tigris

from El Paso and Kermit, Texas are shown in Figure 1. Copu-

lation and courting behavior observed in the field on 19 and

23 May 1971 correlates with maximal size of testes.

Two peaks of adult females with large follicles occured

in May and July 1971 (Fig. 2). Females with oviducal eggs

were collected in May and July. All adult females collected

in July and August 1971 had expanded oviducts, which indicated

they were recently spent. None of the pre-brumation females

collected in late August 1970 had developing follicles or

oviducal eggs. However, in the post-brumation sample (mid-

May 1971? N*3 9), 11 % of the adult females had oviducal eggs,

had follicles with yolk (x= 4*5 - 0.6 mm), and 33% were

non-reproductive. In the June 1971 collection (N= 11),

of the adults had follicles with yolk (x= 1.6 £ 0.1 mm)

whereas 36% were non-reproductive. In the July 1971 collection

(N= 24), 67% of adult females contained follicles with yolk

(x= 5.8 - 0,2 mm) and 33% contained oviducal eggs (x= 9-8 x

17.0 mm). Follicles from females collected in May and July

were significantly larger than follicles from females col-

lected in June (t= 3.75; df= 12; P< 0.01 and t= 2.87; df» 23;

P< 0.05, respectively).

Lipid Cycles

Results of the examination of lipid levels in fat bodies,

livers, ova, and carcasses throughout the year are seen in Fig.

3 through 11, and in Tables 4 and 5 .

Lean Carcass Tissue

Single-factor ANOVA revealed that time (month) had a

significant effect on variation in LCT weights in males (F=

2 . 9 6 ; df= 6, 57) and females (F== 6.47; df= 6, 73). The

mean LCT weight for males (4138.6 - 319.6 mg) was significantly

(t= 23.6: df= 130; P< 0.01) larger than the mean LCT weight

for females (3029.5 - 171.9 mg) (Fig. 3 ) . Means of LCT weights

for monthly collections of males were similar except in July,

when they were significantly higher than other months (Fig.

2). Mean LCT weights of females OSC 1 and 0SC 2 collected

in June were significantly lower than in all other months

(Fig. 4 ) . SVL measurements showed a high correlation to LCT

weights in males (r^ 0.90) and females (r= 0.73).

Fat Body Lipids

Analysis revealed that time (month) significantly

10

contributed to variation in levels of fat body lipids (FL)

of males (F= 2,98; df= 6, 57) and females (F= 7.56; df=

6, 73). Significant reduction of FL occured during brumation

in both sexes (Fig. 5). Females lost significantly more FL

(x=* 142.1 mg) than males (x= 70.1 mg) from August 1970 to

May 1971 (Table 4). FL increased significantly in males

from May to July (83.3 mg) but remained unchanged in females.

Females lost a mean of 35.8 mg of FL from July to early

August 1971.

Analysis revealed that the effect of time (month) signi-

ficantly contributed to variation in FL levels for females

in OSC 1 (F— 6,,34; df= 6, 36) but not for females in OSC 2

(F= 0.47s df= 3, 28). There was a significant depletion of

FL in females in OSC 1 during brumation (Fig. 6), but there

was no significant change in FL levels from May to July for

females in OSC 1 (Table 5). There was a significant difference

between FL levels of females in OSC 2 and OSC 3 in July (t=

4.97; df= 21; P< 0.05).

Liver Lipids

Monthly variation in levels of liver lipids (LL) was

not significant in males (F= 1.59; df= 6, 57) or females

(F= 1.28: 6, 73). The only significant difference in LL

between males and females occured in late August 1970 col-

lections (t= 2.44; df= 28; P< 0.05) (Fig. 7).

11

Carcass Lipids

Monthly variation in carcass lipid (CL) levels was signi-

ficant for males (F= 4• 545 df= 6, 57) and females (F= 5.06;

df= 6, 73). CL levels decreased significantly between late

August 1970 and May 1971 in males and females (Fig. 8).

There was no significant difference in the CL lost by males

(x=« 90.4 mg) and females (x= 110.1 mg) during brumation (Table

4). Males deposited CL in a pattern similar to their FL

deposition with a significant increase (x= 167.9 mg) occuring

between May and July. CL levels did not change significantly

from May to July in females.

Time (month) had a significant effect on variation in

CL levels of females in OSC 1 (F= 7.01; df= 6, 36) but no

effect on CL levels of females in OSC 2 (F= 0.02; df 3, 28).

Significant differences in CL levels were apparent for females

in OSC 1 during brumation (Fig. 9 ) . There was a significant

difference (t= 2.22; df= 23; P< 0.05) in CL levels between

females in OSC 1 of August 1970 and females in OSC 2 in May

1971. No significant change in CL levels of females in OSC 1

from May to July was observed.

Total Lipids

Females had significantly more total lipids (TL= FL + LL +

CL) than males in most collections (Fig. 10). Monthly varia-

tion in TL levels was significant for males (F= 4.10; df= 6,

57) and females (F= 6.02; df= 6, 73). TL levels decreased

significantly during brumation in both sexes (Fig, 10). The

12

difference between the mean TL depletion in males (x= 163.1

mg) and females (x= 217.5 mg) was significant (t= 3.26; df= 19;

P<0.05). Males, but not females, deposited a significant

quantity of TL (x= 248.7 mg) in fat bodies and carcasses from

May to July (Table 4). Females lost a mean of 168.2 mg of

TL from July to early August 1971 whereas TL levels in males

remained unchanged for the same period.

Analysis revealed that time (month) had a significant

effect on TL level variance for females in OSC 1 (F= 6.80;

df= 6, 36) but no effect on females in OSC 2 (F= 0.04; df=

3, 28). TL depletion was significant for females in OSC 1

during brumation, but remained unchanged from May to July

(Fig. 11). There was a significant depletion of TL for fe-

males in OSC 2 of July and females in OSC 1 of August 1971

(t= 4.37; df=» 21; P< 0.05). TL levels were significantly

different for females in OSC 2 of July and females in OSC

1 of August 1971 (t= 2.37; df= 12; P< 0.05).

CHAPTER IV

DISCUSSION

Field Observations

The biased sex ratios in ray monthly collections may

partially result from females restricting their activities

to mesquite mounds, whereas males range more widely. Since

it was impossible to distinguish sexes in the field before

capture, sex ratios of the collections represent frequency

of encounters and not necessarily true sex ratios. Adult

males out-numbered adult females in every collection. The

overall ratio of 3 s 2 (males to females) is in accord with

previous reports for whiptails (Hoddenbach, 1965; McCoy,

1965: Tanner and Jorgenson, I963). The ratio of juvenile

males to females, though biased in some months, was equal in

the total sample. Equal ratio of juvenile males to females

has been previously reported (Hoddenbach, 1965) and suggests

that differential mortality during the egg stage does not

account for the unequal sex ratios in adult collections.

The lower number of adult females than males in my mid-May

and early August collections may be explained by the cryptic

behavior of gravid females. Most adult females oviposit

during early June and early August in El Paso. Blair (I960)

and Anderson (1962) suggested that heavy egg burdens which

impair locomotion and feeding activities may account for the

13

14

cryptic behavior of gravid females. Cryptic behavior may

have adaptive value in reducing chances of predation on

gravid females whose agility is impaired by heavy egg burdens.

Hoddenbach (1965) suggested that biased sex ratios in col-

lections were an artifact produced by differential activities

of the two sexes. McCoy (1965) suggested that there is an

actual bias which results from differential mortality. Dif-

ferent microhabitat preferences, size of home ranges, differ-

ential mortality, and cryptic behavior of gravid females, all

probably contribute to unbalanced sex ratios of adults in

my collections,,

The difference in the length of seasonal activity of

adults and juveniles that I observed probably was a result

of the additional feeding time required by juveniles prior

to brumation. Longer seasonal activity by juvenile C. tigris

has previously been reported (Echternacht, 1964; Hoddenbach,

I965? McCoy, 1965)- Woodbury and Woodbury (1945) suggested

that juvenile Sceloporus graciosus begin brumation later than

adults because they require more feeding time. Since both

adult and juvenile whiptails consume similar food items (e.g.,

termites, bettles) (Milstead, 1958; Pianka, 1970) earlier

brumation by adults may fortuitously remove them from compe-

tition with juveniles.

Reproductive Cycles

The changes in size of gonads and copulation that I

observed in the field in adult C. tigris suggest that mating

15

occurs during late May; when the testes of males are of maximal

size: and that adult females probably produce two clutches

annually, one in early June and a second in early August.

McCoy (1965) and Hoddenbach (1965) report that C. tigris

mates only in late spring, whereas, Milstead (1957b) reported

that mating lasts from 28 May to 31 July.

Adult females which emerge from brumation with yolk in

their follicles, produce oviducal eggs and deposit them by

early June and another clutch by early August. All adult

females collected in August 1970 and 1971 were non-reproduc-

tive, indicating that females enter brumation without yolking

follicles or oviducal eggs. Echternacht (1964) and Hoddenbach

(1965) also report that adult females enter brumation without

oviducal eggs or follicles with yolk. Females I collected

in early spring, immediately after brumation, had follicles

with yolk. Apparently some females begin depositing yolk in

follicles during brumation. Hoddenbach (1965) reported that

because of the small size of his early spring collection he

could not confirm whether or not some yolking of follicles

occurs during brumation. However, he reported that most

females collected in early May had follicles with yolk, indi-

cating rapid yolking occurs after emergence. All females I

collected in July had either follicles with yolk or oviducal

eggs. Most of these females had expanded oviducts, which indi-

cates they were recently spent. Therefore, it is apparent

they were producing their second seasonal clutch. Hoddenbach

16

(1965) also reported that C. tigris from West Texas layed two

clutches. However, recently matured females may lay one or

two clutches depending upon whether maturation occurs early

or late during their first season as a reproductive (Hoddenbach,

1965)« Late maturation in the first season as an adult, could

account for the presence of several non-reproductive females

in my mid-May collection, while all females collected in July

were reproductive.

The number of follicles with yolk and oviducal eggs (i.e.,

potential clutch size) as well as number of clutches laid

per season vary geographically in C. tigris (McCoy and

Hoddenbach, 1966: Pianka, 1970). Females from northern parts

of the range lay one clutch with an average of 3.4 eggs while

females from southern parts of the range lay two clutches each

with an average of 2.3 eggs (McCoy and Hoddenbach, 1 9 6 6 ) .

However, throughout its range the size of the largest follicles

produced and mean size of oviducal eggs are relatively constant.

The largest size of' follicles with yolk and mean size of ovi-

ducal eggs I measured w a s in accord with that reported by

Echternacht ( I 9 6 4 ) , Hoddenbach (1965), McCoy ( I 9 6 5 ) , Pianka

(1970), and Shaw ( 1 9 5 2 ) . Apparently, maximal size of follicles

with yolk and oviducal eggs is less variable than the number

of follicles produced or number of clutches laid. Variable

environmental factors (e.g., length of growing season, rain-

fall, food supply) have been reported to influence size and

number of cluches in C. tigris (McCoy and Hoddenbach, 1966;

17

Pianka, 1970) and probably accounts for conflicting reports

on numbers of yolked follicles produced (Carpenter, I960;

Fautin, 1946; Gehlbach, 1965; Goldberg and Lowe, 1966;

Stebbins, 1954)•

Lipid Cycles

Lean Carcass Tissue

Since my collection in July contained more large males

than in other collections, the mean weight of LCT was corres-

pondingly higher than in other monthly collections. Large

males were probably more active (foraging) than small males

because of their preparation for earlier entrance to brumation

(late July). McCoy (1965) and Hoddenbach (1965) reported

that large males were most abundant in July and began brumation

before females and small males in late July, My June col-

lections of females were smaller than in other collections

and therefore, had smaller LCT weights than other months.

Apparently, large females were brooding their first clutch

Gf the season and their cryptic behavior reduced the chances

of their being collected. None of these small females col-

lected in June had expanded oviducts, indicating that they

were probably producing their first clutch.

Fat Body. Liver. and Carcass Lipids

Females had significantly larger lipid reserves in their

carcasses and tat bodies than males immediately before and

after brumation. Although there was no significant difference

18

in the amounts of carcass lipids depleted by each sex, females

used significantly more fat body lipids than males during

brumation. Since both sexes probably experience similar

physical conditions during brumation (i.e., temperature,

fasting), their energy requirements for maintenance should

be nearly equivalent. Therefore, the additional lipids de-

pleted from fat bodies by females were probably used in the

production of the yolk. The presence of follicles with yolk

in recently emerged females supports this hypothesis. The

use of carcass lipids for maintenance during brumation has

been reported for other lizards (Avery, 1970; Darevsky, 1957;

Dessauer, 1953, 1955; Moberly, 1963) and salamanders (Fitzpatrick,

1970).

Fat body lipids appear to be used by females that are

producing yolk during May and July. Fat bodies have been

reported to be involved in gonadal maintenance (Adams and Rae,

1929; Altland, 1941) and show an inverse size relationship

with follicle development in many ectothermic vertebrates

(Barwick, 1959; Bostic, 1964; Fitzpatrick, 1970; Hahn and

Tinkle, 1965; Hoddenbach, 1965} Lewis and Rose, 1969j Marion

and Sexton, 1971; Mayhew, 1971; Miller, 1948; Pianka, 1970;

Rose and Lewis, 1968; Smith, 1968; Telford, 1970). Hahn and

Tinkle (1965) reported that although fat body lipids appear

to be used for the production of the first clitch in the liz-

ard, Uta stansburiana. fat body lipids are not used for pro-

duction of subsequent clutches. Rather, they suggest that

19

feeding is sufficient to supply all the energy needs for the

second and third clutches. Surely limited feeding has an

impact on the energy requirements of gravid female C. tigris

while brooding. Although gravid female C. tigris are cryptic

and difficult to capture on my study site, gravid U. stans-

buriana are active and easily collected. Though feeding may

be significantly decreased, thereby requiring greater energy

depletion for maintenance during vitellogenesis, the adaptive

value would be an increased surviorship among gravid females.

Hoddenbach (1965) reported the life expenctancy of U. stans-

buriana to be one year, while C. tigris has a life expec-

tancy of at least four years.

The higher lipid levels in livers of females than males

during late August suggest that females were storing lipids

at a greater rate than males. After production of the second

clutch in early August, females were severely depleted of

lipids, whereas males have replenished lipid reserves which

they depleted during brumation. Females which produced a

second clutch had only one month to replace approximately

twice the amount of lipids that males replaced in two months.

Therefore, these females should be processing large quantities

of lipids through the liver for deposition in the carcass and

fat bodies. Telford (1971) reported that wet weight of livers

is maximal in the lizard, Takydromus tachydromides. prior

to brumation.

The energy expended by males for maintenance and females

20

for maintenance and production of ova during brumation can

be approximated by converting the weight of lipids depleted

(Tables 4 and 5) into calories. Since the mean caloric

equivalent of lipids is 9000 cal g~̂ - (White et aJL., 1964),

the minimal energy used by males and females during brumation

was 1468 and 1.952 calories, respectively. If both sexes

expended nearly equivalent amounts of energy for maintenance

during brumation, the additional 484 calories used by females

represent reproductive costs. The average caloric equivalent

of lipids in the follicles with yolk in females which had re-

cently emerged from brumation was 407 calories. The additional

77 calories probably represent energy expended for synthesis

of yolk, lipid mobilization, etc. The amount of lipid de-

pleted while females were producing their second clutch (July

to early August), averaged 2531 calories. The average caloric

equivalent of lipids in oviducal eggs was 1196 calories. This

difference in energy (1335 calories) probably represents energy

depleted for maintenance during brooding and synthesis of yolk.

Acknowledgements

I would like to thank Dr. Ben G. Harris (North Texas State

University) for helpful suggestions on lipid extraction pro-

cedures. I wish to express my gratitude to Drs. John R.

Bristol, Albert G. Cannaris, Curtis E. Eklund, and Richard

D. Worthington of the University of Texas at El Paso for pro-

viding laboratory space and assistance. For helpful discussion

21

of the study I thank Dr. Charles 0. McKinney (University

of Dayton), Dr. Walter G. Whitford (New Mexico State Uni-

versity), and Dr. Eric Pianka (University of Texas at

Austin). For assistance in field collections my thanks to

Mr. Arves E. Jones, Jr., and Mr. Vincent Gentz of El Paso,

Texas.

22

APPENDIX

23

w <D U 3 -P ftJ u (U & CD 4J M

•rj ro g

3 E a •H e

c m

G m Q) B

m e >1 o

rH r-rd <r> •P H

tjv c

•rH

C 0 e CD tn 3 ro CD 03 > (0 C X I <D I Eh

rH

0) o H CQ

IXJ m 04 &

pH H a •H

U w p

I

Eh U O

a* w CO

O & <

& 04

c

as

m m fe

65

s

VD in

m vd

in i>

0 0

av oo

in cr>

vo CO

r-

vX>

\D

m <3*

CM in

00 \D

r* r-

CM 00

00

CM r-

oo VD

00 m

oo

in

ro ro

& 00

o in

o vo

in VD

o r*

r-KO

oo in

oo

oo

oo ro

00 CM

£

24

10

U tn

•H •P

W 3 1̂

o x : a o

*0 -H g <D G u

fxi

CD H ra g a)

MH •

rH *0 r -a <T> ro rH

f 's, o

a r* <s—* CTi

H CD

»H fcn ro G g •H

3 0 13

U 0 Q) 0)

PQ g fa 0

H 1 W

CM a •H

CD rH A CD fO 4J Eh a

CD rH rH 0 o

CO

15 O Eh

f£ B O EH

!* 3

> CO

CN l> Ai

8

I

fa

fa

fa

OS VO in

CM r^ CO <T\

LO r -

00 V0

oo in

oo <3*

(30

GO

o iH

in

00 oo

00

o H

in r-4

o m

VD 00

Eh

B <<

o r -m

w PQ

s

8

0

01

1-3 H «H PS fa as *C H

i> CM

o VD

CM

r -vD

r -oo

00 00

in CM

ro

o CM

<Tv H

00

Cft

CM

00 vO

00

00 CM

00

00 CM

CM

£h r* < CTI S »H

I •o

1> Cft

Eh

B

B <C

01

00 m

oo

CM

in

oo r -

o r l

o CM

CO »-5 g

O, EH

25

Table 3—Monthly variations in collections of male and female Cnemidophorus tigris on specific sites (mounds and open) by month for 1971. See text for discussion of specific sites.

MAY JUNE JULY AUGUST TOTAL

ADULT MOUND 33 26 7 6 72 MALES

OPEN 6 24 27 15 71

MOUND 15 8 3 0 26 JUVENILE MALES

OPEN 17 12 1 0 30

MOUND ADULTS

10 8 18 4 40

FEMALES OPEN 3 3 6 11 23

MOUND JUVENILE

9 0 4 1 14

FEMALES OPEN 6 0 2 0 8

Table 4—Mean ± standard deviation of snout-vent length of lipids (LIP in mg), total tissue (TOT in mg) and percent for monthly samples of males (M) and females (F).

MONTH SEX SVL LCT FAT 1 BODIES LIVER (N)

LIP TOT % LIP TOT % M B3.3 '3990.3 79.9"~ 88.4 90.4 13.0 48.1 27.0

LATE (16) ±1.0 ±178.7 ±31.5 ±33.5 ±3.2 ±1.8 ±5.3 ±2.4

AUGUST 1970 F 78.0 3576.7 209.3 222.3 94 o 2 16.7 52.8 31.6

(18) ±3„7 ±121.2 ±35.2 ±36.6 ±1.5 ±1.4 ±3,5 ±1.6

M 83.6 4097.7 9.8 11.4 85.9 10.5 63.2 16.6 (10) ±0.7 ±170.4 ±6.5 ±6.9' ±7.5 ±1.4 ±3.8 ±2.5

MAY 1971 F 79.1 3174.9 63.1 66.8 94.5 12.3 64.6 19.0

(9) ±1.4 ±182.5 ±21.9 ±22.4 ±1.5 ±1.9 ±9.3 ±1.8

M 82.5 3968.1 9.4 11.3 83.2 9.5 71.3 13.3 (11) ±1.2 ±272.0 ±2.5 ±2.6 ±5.1 ±1.4 ±6.5 ±2.6

JUNE 1971 F 72.3 2298.6 32.6 34.7 93.9 11.2 42.4 26.4

(11) ±1.7 ±173.6 ±6.7 ±10.8 ±3.7 ±1.9 ±2.8 ±3.9

M 87.3 4700.2 93.1 99.6 93.5 13.7 94.1 14.7 (10) ±1.0 ±218.5 ±36.4 ±37.4 ±1.9 ±2.1 ±7.7 ±1.8

JULY 1971 F 78.5 2896.9 52.9 - 57.2 92.5 13.5 73.8 18.3

(24) ±1.2 ±133.8 ±1.7 ±17.5 ±1.9 ±1.6 ±5.4 ±1.7

M 82.5 3937.0 39.1 44.6 87.7 17.5 80.3 21.8 EARLY (5) ±1.7 ±282.6 ±15.8 ±17.6 ±4.2 ±3.2 ±5.2 ±3.3 AUGUST 1971 F 79.2 3101.2 17.1 18.9 90.5 14.9 65.6 22.7

(6) ±1.9 ±319.6 ±9.8 ±10.4 ±9.1 ±2.7 ±7.6 *2.9

MID AUGUST F 78.5 3128.9 64.5 68.9 93.6 12.3 50.6 24.3 1971 (5) ±3.2 ±393.3 ±48.2 ±51.5 ±1.4 ±1.1 ±9.0 ±3.6

26 (SVL in mm) and lean carcass tissue (LCT in mg); and dry weight lipids (%) for fat bodies, liver, ova, carcass and total tissue

OVA

LIP TOT %

CARCASS

LIP TOT 2 0 5 . 5 4 1 1 0 . 0

%

TOTAL

LIP TOT % 2 9 8 . 5 4 2 5 5 . 0 770" ± 6 6 . 1 ±259 .5 ± 0 . 9 *36.7 ±111.7

5 . 0 ±0.6

3 2 7 . 7 3 9 0 4 . 7 8 . 4 ±21 .9 ±119 .0 ±0 .6

5 5 3 . 7 4 1 8 1 . 6 1 3 . 2 ±50 .6 ±121 .2 ± 2 . 9

1 1 5 . 1 4 2 2 1 . 8 2 . 7 ± 1 8 . 8 ±182 .7 ± 0 . 3

1 3 5 . 4 4 3 0 1 . 5 3 . 1 ± 2 9 . 4 ± 1 8 4 . 6 ± 0 . 5

6 5 . 2 1 8 1 . 5 3 5 . 9 2 3 9 . 3 3 4 1 9 . 8 6 . 9 ± 4 2 . 5 ± 3 5 . 4 ± 9 . 1 ± 1 9 . 1 ± 1 8 2 . 8 ± 0 . 6

3 3 6 . 8 3 6 6 0 . 6 9 . 2 ± 4 7 . 7 ± 2 3 4 . 1 ± 1 . 0

- 1 5 3 . 5 4 1 2 1 . 6 3 . 7 ± 1 7 . 6 ± 2 7 0 . 9 ± 0 . 5

1 7 2 . 3 4 2 0 1 . 5 4 . 1 ± 1 8 . 4 ± 2 7 6 . 1 ± 0 . 5

4 . 6 6 . 2 7 4 . 2 ± 1 . 9 ± 2 . 4 ± 1 . 1

1 8 0 . 0 2 4 7 9 . 6 7 . 3 ± 1 7 . 3 ± 1 7 0 . 6 ± 1 . 0

2 0 3 . 4 2 5 5 9 . 7 7 . 9 ± 2 8 . 9 ± 1 7 0 . 3 ± 1 . 3

- 2 8 3 . 0 4 9 8 3 . 3 5 . 7 ± 3 9 . 6 ± 2 4 6 . 9 ± 0 . 7

3 8 9 . 8 5 1 7 6 . 9 7 . 5 ± 7 1 . 1 ± 2 7 1 . 0 ± 1 . 2

4 9 . 5 2 1 9 . 3 2 2 . 6 1 8 7 . 0 3 1 1 1 . 7 6 . 0 ± 1 2 . 8 ± 6 1 . 6 ± 3 . 3 ± 1 7 . 6 ± 1 2 3 . 8 ± 0 . 6

3 0 2 . 9 3 5 1 6 . 8 8 . 7 ± 3 0 . 8 ± 1 3 1 . 5 ± 0 . 8

2 4 5 . 4 4 1 8 2 . 4 5 . 9 ± 4 6 . 1 ± 3 2 5 . 6 ± 0 . 7

3 0 2 . 0 4 3 0 7 . 3 7 . 0 ± 6 3 . 7 ± 3 4 4 . 1 ± 1 . 0

1 1 1 . 9 3 2 1 8 . 1 3 . 5 ± 2 5 . 5 ± 3 3 8 . 2 ± 0 . 6

1 4 3 . 9 3 3 0 2 . 6 4 . 4 ± 3 5 . 7 ± 3 5 3 . 8 ± 0 . 7

1 4 9 . 8 3 2 7 8 . 8 4 . 6 ± 2 8 . 4 ±410 .5 ± 0 . 7

2 2 6 . 6 3 3 7 1 . 7 6 . 7 ± 7 1 . 9 ± 4 2 3 . 2 ± 1 . 3

Table 5—Mean ± standard deviation of snout-vent length of lipids (LIP in mg), total tissue (TOT in mg) and percent for monthly samples of females placed in ova size classes (OSC)

MONTH OSC SVL LCT FAT BODIES LIVER (N)

LIP TOT % LIP TOT % AUGUST 1 78.0 3576.7 209.3 222.3 94.2 16.7 52.8 31.6 1970 (18) ±3.7 ±121.2 ±35.2 ±36.6 ±1.5 ±1.4 ±3.5 ±1.6

1 76.5 2935.0 48.6 51.9 93.6 6.0 44.3 13.5 (3) ±7.1 ±499.6 ±15.0 ±15.3 ±2.6 ±0.3 ±7.2 ±2.6

MAY 1971 2 81.4 3243.4 81.4 85.6 95.1 15.7 78.8 19.9

(5) ±4.3 ±167.3 ±37.8 ±38.6 ±2.4 ±1.9 ±3.4 ±1.7

1 68.2 1916.8 35.1 37.6 93.4 8.T 34.8 23.3 (4) ±2.2 ±135.5 ±18.9 ±20.1 ±5.8 ±1.8 ±4.0 ±4.0

JUNE 1971 2 74.7 2516.8 31.2 33.0 94.5 13.0 46.8 27.8

(7) ±5.9 ±227.8 ±13.8 ±13.7 ±5.4 ±2.7 ±2.6 ±5.7

2 77.9 2988.6 77.7 * 78.6 98.6 13.6 75.9 17.9 (16) ±6.2 ±171.2 ±24.6 ±24.6 ±1.6 ±2.1±7.0±2.0

JULY 1971 3 79.7 2837.6 15.0 18.4 81.5 13.8 69.7 19.8

(8) ±4.8 ±199.2 ±8.1 ±6.7 ±4.4 ±3.4±8.7±2.9

AUGUST 1 79.2 3101.2 17.1 18.9 90.5 14.9 65.6 22.7 1971 (6) ±1.9 ±319.6 ±9.8 ±10.4 ±9.1 ±2.7±7.6±2.9

27

(SVL in mm) and lean carcass tissue (LCT in mg); and dry weight lipids (%) for fat bodies, liver, ova carcass and total tissue

OVA CARCASS TOTAL

L I P TOT % EXP TOT % LIP TOT % - - - 3 2 7 . 7 3 9 0 4 . 7 8 . 4 553 .7 4 1 8 1 . 6 1 3 . 2

± 2 1 . 9 ±119 .0 ± 0 . 6 ± 5 0 . 6 ±121 .2 ± 2 . 9

Mi 1 6 7 . 5 3 1 0 2 . 5 5 . 4 2 2 2 . 1 3 1 6 2 . 0 7 . 0 ± 3 2 . 7 ± 4 7 9 . 1 ± 1 . 8 ± 4 7 . 8 ± 4 6 7 . 7 ± 2 . 3

2 2 . 9 4 3 . 6 52 . 5 2 4 2 . 0 3 5 3 4 . 5 6 . 8 3 6 2 . 6 3 7 4 5 . 2 9 . 7 ± 4 . 5 ± 6 . 8 ±1 . 0 ± 2 0 . 9 ±160 .7 ± 0 . 4 ± 5 5 . 2 ± 1 9 1 . 0 ± 1 . 1

•M. 1 7 1 . 3 2 0 8 8 . 1 8 . 2 2 1 4 . 5 2 1 6 0 . 4 9 . 9 ± 3 9 . 3 ± 1 4 6 . 8 ± 1 . 8 ± 5 6 . 1 ± 1 5 4 . 2 ± 2 . 5

4 . 6 6 . 2 7 4 . 2 1 8 5 . 1 2 7 0 1 . 9 6 . 9 233 . 9 2 7 8 7 . 9 8 . 6 ± 1 . 9 ± 2 . 3 ± 1 . 1 ± 1 8 . 1 ± 2 1 8 . 0 ± 1 . 1 ± 3 5 . 2 ± 2 1 2 . 8 i 1 . 7

1 6 . 2 4 2 . 9 3 7 . 8 2 3 1 . 1 3 1 8 5 . 6 7 . 3 3 3 8 . 6 3 4 2 7 . 5 9 . 8 ± 3 . 5 ± 9 . 4 ± 3 . 7 ± 1 5 . 8 ± 1 7 1 . 0 ± 0 . 5 ± 4 1 . 3 ± 1 9 7 . 2 ± 0 . 9

1 3 2 . 9 6 2 3 . 8 2 1 . 3 1 1 9 . 5 2 9 6 3 . 9 4 . 0 2 8 1 . 2 3 6 5 9 . 3 7 . 7 ± 1 7 . 2 ± 6 8 . 9 ± 3 . 9 ± 3 5 . 0 ± 1 4 4 . 8 ± 1 . 3 ± 5 8 . 3 ± 1 3 5 . 9 ± 1 . 6

— 1 1 1 . 9 3 2 1 8 . 1 3 . 5 1 4 3 . 9 3 3 0 2 . 6 4 . 4 ± 2 5 . 5 * 3 3 8 . 2 ± 0 . 6 ± 3 5 . 7 * 3 5 3 . 8 * 0 . 7

28

Figure 1—Monthly, variation in mean testes size (length + width in mm) for Cnemidophorus tigris from El Paso (triangles) and Kermit, Texas (circles). Data from Kermit from Hoddenbach (1965).

o 00 CD

N CD =3 <

D

C

3

R O) D

<

mmmmmmrn

«MMJLM»

o

( M + ~ l ) 3 Z I S S 3 1 S 3 1 N V 3 1 A 1

29

Figure 2—Monthly variations in size of follicles (dia-meter in mm) for Cnemidophorus tigris females. Means are the horizontal lines; standard deviation the rectangles; and 95% confidence limits the vertical lines.

CD D <

R

CD ^ c\J O

(LULU Ul) S3~iomoddo daiaiAivia

X

O

30

Figure 3—Monthly variations in lean carcass tissue means (horizontal lines), standard deviation (rectangles) and 95% confidence limits (vertical lines) for male (open rectangles) and female (closed rectangles) Cnemidophorus tigris.

I o o o in

i o o o

± o o o CO

1 o o o

O) <

F: D)

£ =3 ~>

13

IE j w M M M

z O

£

R I

(6uj)3nSSIl SSVOdVD NV3~1

31

Figure 4—Monthly variations in weights of lean carcass tissue for females in three ova size classes (OSC). Means are the horizontal lines? standard deviation the rectangles; and 95% confidence limits the vertical lines. OSC 1 females are the open rectangles; OSC 2 females the closed rectangles; and OSC 3 females the black and white rectangle.

- c

V/-

1 1 o o o

ID O O O

1 o o o 00

1 o o o C \ J

(AJ i

O) 3 N 3 N C 3

13 R CD 3 <

o o

ID (6w)3nssil SSVOdVD NV31

I I— z: o

32

Figure 5—Monthly variations in percentage of lipids (dry weight) in fat bodies compared to lean carcass tissue weights for male and female Cnemidophorus tigris. Symbols same as in Figure 2.

00 CD CM

mm

mm

CVJ

'S, O )

E • 3

IE I—

o §•

R O )

O

Q l d l l ! N 3 0 d 3 d

'33

Figure 6—Monthly variation in percentage of lipids (dry weight) in fat bodies compared to lean carcass tissue weights for female Cnemidophorus tigris in three ova size classes. Symbols same as in Figure 3.

CM

nttwum

•W

<

I

S 3

h * C D

5

R

x z: O

CD CD CM o

a i d n i N 3 o ^ 3 d

34

Figure 7—Monthly variations in percentage of lipids (dry weight) in livers compared to lean carcass tissue weights for male and female Cnemidophorus tigris. Symbols same as in Figure 2.

.

— %

CD

O

mm,

jfrMiiiM

T̂ CM

aidn o o lN30d3d

CM

£v C7) D <

h -ay

3

•=J

D

N

R

o

X I-z: O

35

Figure 8—Monthly variations in percentage of lipids (dry weight) in carcasses compared to lean carcasses tissue weights of male and female Cnemidophorus tigris. Symbols same as in Figure 2.

W < M

00 (O CM

c\]

R D) D <

S

5

I R D) 5 <

I— Z o

aid 11 iN3DM3d

36

Figure 9—Monthly variations in precentage of lipids (dry weight) in carcasses compared to total carcass tissue weights for females Cnemidophorus tigris in three ova size classes. Symbols same as in Figure 3.

- f t -

—J— 1—1—1 1—I—i—i « « i ^ O

C\J CJ)

* I I—

<- z X A M H £ o

R 3> <

m o

Qldll INBOdBd

37

Figure 10—Monthly variations in percentage total lipids (dry weight) compared to total tissue weights for male and female Cnemidophorus tigris. Symbols same as in Figure 2.

\o

'

' 1 * ,r

O

- I — > — « ....1—« i -» L

in Cvj / A i

CM

9 <

D)

N

3

%

N &

2 R O ) 3 <

|hmm«W»

z O 2

aidn iN30d3d

38

Figure 11 —Monthly variations in percentage total lipids (dry weight) compared to total tissue weight for female Cnemidophorus tigris in three ova size classes. Symbols same as in Figure 3.

H:

CD eg

-/A o OJ 1——1 1 • » I o a L

eg

O) =J <

U )

b u

c •=?

r̂

X I—

o

R O) 3 <

o

a Id I I lN30&3d

L I T E R A T U R E C I T E D

Adams, A. E. and E, E. Rae. 1929. An experimental study of the fat bodies in Diemectylus viridescens. Anat. Rec. 41: 181-204.

Altland, P. D. 1941. Annual reproductive cycle of the male fence lizard. Elisha Mitchell Scientific Soc. Jour. 57: 73-84.

Avery, R. A. 1970. Utilization of caudal fat by hibernating common lizards, Lacerata vivipara. Comp. Biochem. Physiol. 37: 119-121.

Barwick, R. E. 1959. The life history of the common New Zea-land skink, Leiolopisma zealandia (Gray, 1843). Trans. Roy. Soc. New Zealand 86: 331-380.

Blair, W. F. i960. The rusty lizard, a populational study. University of Texas Press, Austin, Texas. I80p.

Bostic, D. L. I964. The ecology and behavior of Cnemido-phorus hypervthrus beldingj Cope (Sauria: Teiidae). Unpub. M. S. Thesis, San Diego State College. 112p.

Carpenter, C. C. i960. Reproduction in Oklahoma Scelooorus and Cnemidophorus. Herpetologica 16: 175-182.

Clark, D. R. 1971. The strategy of tail-autotomy in the ground skink, Lygosoma laterale. J. Exp. Zool. 176: 295-302.

Darevsky, I. S. 1957. Seasonal change of fat bodies and gonads in some lizards of the Arax River Valley in Armenia. Zoologichesini Zhurnal 39: 1209-1218.

Dessauer, H. C. 1953- Hibernation of the lizard, Anolis car-olinensis. Proc. Soc. Exp. Biol. Med. 82: 351-352.

Dessauer, H. C. 1955« Seasonal changes in the gross organ composition of the lizard, Anolis carolinesis. J. EXD. Zool. 128: 1-12.

Echternacht, A. C. 1967. Ecological relationships of two species of the lizard genus Cnemidophorus in the Santa Rita mountains of Arizona. Am. Midi. Nat. 78: 488-459.

39

40

Fautin, R. W. 1946. Biotic communities of the northern desert shrub biome in western Utah. Ecol. Mono. 16: 251-310.

Fitzpatrick, L. C. 1970. The energy allocation to repro-duction by the female Allegheny Mountain salamander Desmognathous ochrophaeus. Ph. D. dissertation, Kent State University, Kent, Ohio. 115p.

Folch, J., M. Lees and G. Sloane-Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226: 497-509*

Gehlbach, F. R. 1965. Herpetology of the Zuni Mountain re-gion, northwestern New Mexico. U. S. Natl. Museum, Proc. 116: 243-332.

Goldberg, S. R, and C. H. Lowe. 1 9 6 6 . The reproductive cycle of the Western Whiptail lizard (Cnemidophorus tigris) in southern Arizona. J. Morphol. 188: 543-548.

Hahn, W. E. and D. W. Tinkle. 1 9 6 5 . Fat body cycling and experimental evidence for its adaptive significance to ovarian follicle development in the lizard Uta stans-buriana. J. Exp. Zool. 158: 70-86.

Hoddenbach, G. A. 1 9 6 5 . A comparison of reproduction in two lizards: Cnemidophorus tigris marmoratus and Uta stans-buriana ste.ineri. Master's thesis, Texas Tech. College, Lubbock, Texas.

Lewis, H. L. and F. L. Rose. 1969. Effects of fat body fatty acids on ovarian and liver metabolism of Ambystoma tigrinum. Comp. Biochem. Physiol. 30: 1055-1060.

Marion, K. R. and 0. J. Sexton. 1971• The reproductive cycle of the lizard Sceloporus malchiticus in Costa Rica. Copeia 1971: 517-526.

Mayhew, W. W. 1 9 6 5 . Hibernation in the horned lizard Phv-nosoma m'calli. Comp. Biochem. Physiol. 16: 103-119.

1971. Reproduction in the desert lizard Dip-sosaurus dorsalis. Herpetologica 27: 57-76.

McCoy, C. J. 1 9 6 5 . Life history and ecology of Cnemidophorus tigris septrionalis. Ph. D. dissertation, University of Colorado, Bolder, Cblorado. 167p.

_and G. A. Hoddenbach. I 9 6 6. Geographic varia-tion in ovarian cycles and clutch size Cnemidophorus tigris. Science 154: 1671-1972.

... 41

Medica, P. A. 1967* Food habits, habitat preferences, repro-duction and diurnal activity in four sympatric species of whiptail lizards (Cnemidophorus) in South Central New Mexico, Bull. So. Calif. Acad. Sci. 66: 251-276.

Miller, W. M. 1948. The seasonal histological changes oc-curring in the ovary, corpus luteum, and testis of the viviparous lizard, Xantusia vigilis. Univ. Calif. (Berkely) Publ. Zool. 47: 197-224.

Milstead, ¥. W. 1957a. Observations of the natural history of four species of whiptail lizard, Cnemidophorus (Sauria, Teiidae) in Trans-Pecos Texas. Southwestern Nat. 2: 105-121.

. 1957b. Some aspects of competition in natur-al populations of whiptail lizards (genus Cnemidophorus). Texas J. Sci. 9: 410-447.

- 1958. A list of the arthropods found in the stomachs of whiptail lizards from four stations in South-western Texas. Texas J. Sci. 10: 4 4 3 - 4 4 8 .

Moberly, W. R. 1 9 6 3 . Hibernation in the desert iguana, Dip-sosausorus dorsalis. Physiol. Zool. 36: 152-160.

Pianka, E. R, 1970. Comparative autecology of the lizard Cnemidophorus tigris in different parts of its geographic range. Ecology 51: 703-720.

Rose, F. L. and H. L. Lewis. 1 9 6 8 . Changes in weight and free fatty acid concentration of fat bodies of paedo-genic Ambystoma tigrinum during vitellogenesis. Comp. Biochem. Physiol. 26: 149-154,

Shaw, C. E. 1952. Notes on the eggs and young of some United States and Mexican lizards. Herpetologica 8: 71-79.

Shreve, F. 1942. The desert vegetation of North America. Botan. Rev. 8: 195-246.

Smith, R. E. 1968. Experimental evidence for a gonadal-fat body relationship in two lizards (Amevia festiva. A. quadrilineata). Biol. Bull. 134; 325-331.

Sokal, R. R. and F. J. Rohlf. 1969. Biometry. W. H. Freeman and Co., San Francisco. 776p.

Stebbins, R. C. 1954• Amphibians and reptiles of western North America. McGraw-Hill Book Co., Inc. New York.

42

Steele, R. G. and J. H. Torrie. I960. Principles and pro-cedure of statistics. McGraw-Hill Book Co., Inc. New York.

Tanner, W. W. and C. D. Jorgensen. 1963. Reptiles of the Nevada Test Site. Brigham Young Univ. Sci. Bull., Biol. Ser. 3s 1-31.

Telford, S. R. 1970. Seasonal fluctuations in liver and fat body weights of the Japanese lizard Takydromus tachy-dromides Schlegel. Copeia 1970: 681-688.

White, A., P. Handler, and F. L. Smith. 1964* Principles of biochemistry. McGraw-Hill. New York. 1106p.

Woodbury, M. and A. M. Woodbury. 1945. Life-history studies of the sagebrush lizard Scelooorus g. graciosus with special reference to cycles in reproduction. Herpeto-logica 2; 175-196.