DIETARY, TEMPORAL AND HABITAT RESOURCE PARTITIONING BY FOUR

GEKKONID LIZARDS (SAURIA: GEKKONIDAE) AT UNIMAS CAMPUS, KOTA

SAMARAHAN, SARAWAK

Syazwan Affandi bin Zulkipli

Bachelor of Science with Honours

(Animal Resource Science and Management)

2013

Faculty of Resource Science and Technology

DIETARY, TEMPORAL AND HABITAT RESOURCE PARTITIONING BY FOUR

GEKKONID LIZARDS (SAURIA: GEKKONIDAE) AT UNIMAS CAMPUS, KOTA

SAMARAHAN, SARAWAK

SYAZWAN AFFANDI BIN ZULKIPLI

This project is submitted in partial fulfillment of

the requirements for the Degree of Bachelor of Science with Honours

(Animal Resource Science and Management)

Faculty of Resource Science and Technology

UNIVERSITI MALAYSIA SARAWAK

2013

i

Acknowledgement

Alhamdulillah,

I am very grateful to Allah SWT for His willing and blessing, allowing me to complete

this project entitled Dietary, Temporal and Habitat Resource Partitioning by Four

Gekkonid Lizards (Sauria: Gekkonidae) at Unimas Campus, Kota Samarahan, Sarawak.

First of all, I would like to express my deepest thanks and appreciation to my beloved

parents, En. Zulkipli b. Md Yusof and Pn. Rahimah bt. Abd. Rahim, my family and all

of my friends; for their endless loves, financial support, and encouragement from the

beginning till the end. Special thanks to my supervisor: Prof. Dr. Indraneil Das for all his

contribution of time and helps; in guiding me, giving me continuous ideas, suggestions

and constructive comments on the manuscripts during completion of this thesis. I would

also like to express my sincere gratitude to Nur Syarafina Farhah Shukery, Muhammad

Hafizan Abd Raoff and Pui Yong Min for their willing helping me during the sampling

and computing the data analysis. My thanks also go to all lecturers, staffs and students of

Departments of Zoology, who are involved direct or indirectly during this project. Last

but not the least, thanks to Department of Zoology, Faculty Resource Science and

Technology for giving the opportunity to conduct this project.

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DECLARATION

I hereby declare that the Final Year Project Report is based on my original work except

for quotations and citations, which have been duly acknowledged. No portion of the

work in this dissertation has been submitted in support of an application for another

degree of qualification of this or any other university or institution of higher learning.

………………………………...

(Syazwan Affandi bin Zulkipli)

Department of Animal Resource Science and Management

Faculty of Resource Science and Technology

Universiti Malaysia Sarawak

iii

Table of Contents

Acknowledgement………………………………………………………………………. I

Declaration………………………………………………………………………………. II

Table of Contents……………………………………………………………………….. III

List of Abbreviation…………………………………………………………………….. VI

List of Tables…………………………………………………………………………… VII

List of Figures…………………………………………………………………………... VIII

Abstract…………………………………………………………………………………. 1

1.0 Introduction and Objective………………………………………………………….. 2

1.1 Background Study………………………………………………………………. 2

1.2 Problem Statement……………………………………………………………… 3

1.3 Objectives……………………………………………………………………….. 4

2.0 Literature Review…………………………………………………………………… 5

2.1 Resource Partitioning…………………………………………………………… 5

2.2 Geckos…………………………………………………………………………... 6

3.0 Research Methodology……………………………………………………………… 8

3.1 Study Sites………………………………………………………………………. 8

3.2 Field Observation and Techniques……………………………………………… 8

3.3 Stomach Content Analysis……………………………………………………… 9

3.4 Data Analysis…………………………………………………………………… 10

iv

3.4.1Dominance of Food Item………………………………………………… 10

3.4.2 Niche Breadth……………………………………………………………. 11

3.4.3 Niche Breadth Standardized……………………………………………... 11

3.4.4 Niche Overlap…………………………………………………………… 11

3.4.5 Clustering Analysis……………………………………………………… 12

4.0 Results………………………………………………………………………………. 14

4.1 Species Abundance……………………………………………………………... 14

4.2 Microhabitat…………………………………………………………………….. 17

4.3 Diets…………………………………………………………………………….. 19

4.4 Diel Time (Temporal)…………………………………………………………... 20

4.5 Dominance of Food Item……………………………………………………….. 21

4.6 Niche Breadth…………………………………………………………………… 22

4.6.1 Microhabitat……………………………………………………………... 22

4.6.2 Diet………………………………………………………………………. 22

4.6.3 Diel Time (Temporal)…………………………………………………… 23

4.7 Overlaps……………………………………………………………………….... 23

4.7.1 Microhabitat……………………………………………………………... 23

4.7.2 Diet………………………………………………………………………. 23

4.7.3 Diel Time (Temporal)…………………………………………………… 24

5.0 Discussion…………………………………………………………………………... 25

5.1 Observation……………………………………………………………………... 25

5.2 Stomach Content Analysis……………………………………………………… 25

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5.3 Microhabitat…………………………………………………………………….. 26

5.4 Diet……………………………………………………………………………… 27

5.5 Diel Time……………………………………………………………………….. 27

5.6 Niche Breadth and Overlap……………………………………………………... 28

5.7 Clustering Analysis……………………………………………………………... 29

6.0 Conclusion and Recommendation………………………………………………….. 32

References……………………………………………………………………………… 33

APPENDIX 1

Data Sampling…………………………………………………………………………... 35

APPENDIX 2

Stomach Content Data………………………………………………………………….. 36

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List of Abbreviation

g Gram

Geh. mutilate Gehyra mutilata

Gek. monarchus Gekko monarchus

H. platyurus Hemidactylus platyurus

H. frenatus Hemidactylus frenatus

m Meter

mm Millimeter

MSVP Multi-Variate Statistical Package

SVL Snout Vent Length

vii

List of Tables

Table 1

Relative Frequency of Samples

Table 2

Frequency Occurrences of The Species At Specific Habitat

Table 3

Summary of Stomach Content

Table 4

Frequency Occurrence of Each Species at Specific Period of Time

Table 5

Percentage of Dominance Food Item by Each Species

Table 6

Niche Breadth in Microhabitat

Table 7

Niche Breadth in Diet

Table 8

Niche Breadth in Diel Time (Temporal)

Table 9

Overlap in the Microhabitat

Table 10

Overlap in Diet

Table 11

Overlap in Diel Time (Temporal)

Table 12

Data recorded during sampling

Table 13

Data recorded during stomach content analysis

viii

List of Figures

Figure 1 Frequency occurrences of each species in UNIMAS campus

Figure 2

Gekko monarchus

Figure 3

Hemidactylus frenatus

Figure 4

Hemidactylus platyurus

Figure 5

Gehyra mutilata

Figure 6

Percentage of particular species at specific microhabitat

Figure 7

Percentage of microhabitat partitioning for four sympatric geckos species

Figure 8

Percentage of each prey in geckos stomach

Figure 9

Percentage of gecko species at specific time period

Figure 10

Dendogram of relation between each species in microhabitat

Figure 11

Dendogram of relation between each species in diets

Figure 12

Dendogram of relation between each species in diel time

1

Dietary, Temporal and Habitat Resource Partitioning by Four Gekkonid

Lizards (Sauria: Gekkonidae) at UNIMAS Campus, Kota Samarahan, Sarawak

Syazwan Affandi bin Zulkipli

Animal Resource and Management Programme

Faculty of Science and Technology

Universiti Malaysia Sarawak

ABSTRACT

A study of resource partitioning among four sympatric geckos species were

conducted at UNIMAS campus over a period of three days. Four species were

collected- Hemidactylus platyurus, Hemidactylus frenatus, Gehyra mutilata and

Gekko monarchus. A total 46 specimens were collected to compare resource use in

terms of diet, microhabitat and use of diel temporal resources. Berger-Parker

Diversity Index, Diversity Index of Simpson (1949) and Mac Arthur and Levi’s

(1967) were used to compute food dominance, niche breadth and niche overlap.

Results show partitioning only for microhabitat and diel time, but not in dietary

resources.

Keywords: gecko, resource partitioning, diet, microhabitat,diel time, overlap.

ABSTRAK

Kajian mengenai pembahagian sumber dalam kalangan empat simpatrik spesis telah

dijalankan di kampus UNIMAS sepanjang tiga hari. Empat jenis spesis telah

dikumpul dan dibandingkan, iaitu Hemidactylus platyurus, Hemidactylus frenatus,

Gehyra mutilata dan Gekko monarchus. Sejumlah 46 ekor sampel telah ditangkap

untuk membandingkan pembahagian sumber dalam mikrohabitat, masa makan dan

diet. Berger-Parker Diversity Index, Diversity Index of Simpson (1949) dan Mac

Arthur and Levi’s (1967) telah diguna pakai untuk menganalisa dominasi makanan,

keluasan niche dan pertindihan niche. Keputusan menunjukkan pembahagian

sumber hanya berlaku di mikro-habitat, masa pemakanan tetapi tidak pada sumber

makanan.

Kata kunci: gecko, pembahagian sumber, diet, microhabitat, masa makan,

pertindihan.

2

CHAPTER 1

INTRODUCTION

1.1 Background Study

Whether species can coexist in the same animal assemblage is determined by

physical and biological factors, the concept referred to as ‘resource partitioning’, first

introduced in the mid-1960s (Schoener, 1965) to refer to ways species differ in their

use of resources. Resource partitioning patterns may generally derive from the

interaction of some categories of causes, including predation, extrinsic and intrinsic

constraints on an organism’s performance, and interspecific competition (Toft,

1985). Thus, the main scopes of resource partitioning studies are not only to describe

the patterns as they occur in living communities, but also to understand factors

causing these patterns (Schoener, 1977).

In this project, I studied diet, habitat and temporal resource partitioning in geckos

including how sympatric species choose food, habitat and time of activity to reduce

competition. Ecological differences in the use of trophic (food), spatial (place) and

temporal (time) resources have long been associated with the structure of biological

community because of their potential to reduce competition, thereby apparently

facilitating coexistence (Pianka, 1975).

The ways species within a communities partition the available resources is a

determinant of the diversity of coexisting species (Pianka, 1974). The ability to share

the resources, which lead to greater niche overlap, will support more species rather

than one with lower niche overlap. An understanding of the level of resource overlap

3

between the existence species will enhance the knowledge on interactions between

these species. In order to understand the competition and determinant of the species

diversity, this study will focus on the ecological requirement of each species within

the study site. The major purpose of resource partitioning studies is to analyze the

limits of interspecific competition and to determine the number of species that can

coexist (Schoener, 1974).

A total of 108 species of lizards are known from Borneo, of which 29 represent the

family Gekkonidae, and 11 of these are endemic to the island (Das, 2004). Geckos

are not only present in forested areas, but are also able to survive within urban areas.

A few species are found on walls of buildings or on wooden houses. Representative

of this group on Borneo are Gehyra mutilata, Gekko monarchus, Gekko gecko,

Hemidactylus brookii, Hemidactylus frenatus, Hemidactylus garnoti, Hemidactylus

platyurus and Lepidodactylus lugubris (Das, 2010). Most of the world’s geckos are

nocturnal rather than diurnal, and on Borneo, all 29 known species are nocturnal in

habits.

1.2 Problem Statement

Lizards are enormously diverse and differ in their morphology, physiology and life

history. Studies on geckos as models allow an understanding of their diet, habitat and

time resource partitioning. In this project, I report variation in food intake, examine

habitat specialization and use of time by different species of geckos. I studied their

stomach contents to see if there are any variations in food types, observe their habitat

and time of activity during the sampling period, based on their location found and the

light intensity of the location.

4

The extent of spatial overlap between sympatric species largely determines the

potential for competition for all resources. Dietary overlap can also lead to

interspecific competition. There are no documented information on dietary resource

partitioning between sympatric gecko species in Sarawak or indeed, anywhere in

Borneo. Recent studies have forced a reassessment of this perception, because it is

increasingly clear that some reptiles exhibit complex social behaviour and niche

partitioning (Kearney et al. 2001).

1.3 Objectives

The objectives of this research are, to determine whether different sympatric species

of geckos:

a) consume different food resources,

b) utilize different microhabitats and

c) are active at different time

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CHAPTER 2

LITERATURE REVIEW

2.1 Resource partitioning

Concepts of resource partitioning, as originally developed, relates to evolutionary

change in species in response to selection pressure generated by interspecific

competition (Walter, 1990). The term earliest use has been attributed to Schoener (Toft,

1985) and MacArthur (1985), Hutchinson (1959), (Walter, 1990). Schoener (1965)

stated that a first stage in the evolution of the sympatric species association is often food

partitioning by size or dimensional properties of the immediate food environment. He

also stated that "The extent to which resource-partitioning patterns in fact result from

pressures, evolutionary or otherwise, to avoid interspecific competition is now more of

an issue than when most of the studies were carried out" (Schoener, 1986). Resource

partitioning among competing species is one of the most important phenomenon in

population biology (Roughgarden, 1976).

Numerous studies have documented the limitation of the distribution and abundance of

reptile species by competitively dominant reptiles. Compilations on how resources are

partitioned among community members that belong to particular taxonomic groups have

been done. For example, Toft (1985) has summarized the available information on

amphibians and reptiles, and Ross (1986) has reviewed the same for fishes.

6

Investigations of resource overlap and interactions between species may provide insight

into the mechanisms of sympatry that are operating. These mechanisms act to decrease

either exploitative competition, by resource partitioning (Schoener 1974), or interference

competition, by avoidance (Case and Gilpin 1974), to facilitate coexistence with a

dominant or predatory species.

Habitat, food and time are the three main resources, believed to be partitioned by

competing species (Pianka, 1975). Animals partition environmental resources in three

basic ways: temporally, spatially, and tropically; that is, species differ in times of

activity, the places they exploit, and/or the food they eat. Such differences in activities

separate niches, reduce competition, and presumably allow the coexistence of a variety

of species (Pianka, 1973).

Schoener (1974) divided available resources into six categories, which are microhabitat,

food type, food size, diel time and seasonal time. Analysis of foraging biology has been

an important subject in ecology and evolutionary biology (Perry and Pianka, 1997).

Members of the Gekkonidae tend to show a complex trend of foraging which are

intermediate, alternating or fluctuating foraging mode which making them poor

understood (Perry and Pianka, 1997). The mode of foraging or the way in which a lizard

uses space can influence both its place and food niches, which widely foraging species

typically have broader place niches than sit-and-wait species and a pairs of lizard species

with high overlap along one niche dimension may have low overlap along another niche

dimension to reduce interspecific competition between them (Pianka, 1973).

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2.2 Geckos

Chou (1975), reported five gecko species associated with houses in Singapore- Gehyra

mutilata, Gekko gecko, Gekko monarchus, Hemidactylus frenatus and Hemidactylus

platyurus, of which the most abundant species was Hemidactylus frenatus.

Most geckos are nocturnal hunters that feed on insects, spiders and other small

invertebrates. The Tokay gecko, Gekko gecko is a large species whose diet includes

heftier prey items, such as small lizards, birds and mammals. Day geckos from the

islands of the Indian Ocean (Phelsuma sp.) feed on insects, but also bolster their diet

with pollen, fruit and flower nectar. Geckos locate on their food using a combination of

sight and smell.Pianka (1973), stated that being active at different time leads to use of

different resources, such as prey species, temporal separation of activities, which will

decrease the competition between lizard species and the most conspicuous temporal

separation of activities is the dichotomy of diurnal and nocturnal lizards, which are

entirely non-overlapping in temporal dimension. Some lizards are strongly restricted to

their respective habitats, and various species have specialized their microhabitats

requirement.Most lizards are insectivorous and fairly opportunistic feeders, taking

without any obvious preference, whatever arthropods they encounter within a broad

range of types and sizes. Smaller species or individuals, however, do tend to eat smaller

prey than larger species or individuals also; differences in foraging techniques and place

and time niches often result in exposure to a different spectrum of prey species. Few

lizard species have evolved severe dietary restrictions but some of them also depend on

the abundance of the food sources (Pianka, 1973).

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CHAPTER 3

RESEARCH METHODOLOGY

3.1 Study Sites

Field work was conducted within an urbanized area in the Universiti Malaysia Sarawak

(UNIMAS) campus, which is located in Kota Samarahan District of Sarawak State,

Malaysia (on Borneo). The targeted sampling sites were buildings and isolated patches

of trees. The original vegetation is mostly peat swamp forests.

3.2 Field Observation and Techniques

Geckos were collected during their natural period of nocturnal activities, which begin

after sunset and extended at least until midnight. The periods of times were designated

into four different parts, which are a) 19:30–20:30 h, b) 20:31–21:30 h, c) 21:31–22:30 h

and 22:31–23:30 h. Most geckos are nocturnal rather than diurnal and at this locality, all

are nocturnal.

The geckos were located by observing using light sources nearby or headlamp within the

dark area. All specimens were caught by using one of the several methods, primarily by

attracting them with a laser pointer and catching them when accessible. Beams from

laser pointers attract gekkonid lizards to the projected light, which possibly is mistaken

for food or perhaps a potential competitor. From their usually high perches, gekkonid

lizards were lured toward my assistant. This technique worked well on walls of buildings

as well as tree trunks, and it is more successful in the early evening than later,

9

presumably when geckos are becoming active and are hungry. Using rubber band is

more effective when the geckos are no longer hungry.

Most individuals were grabbed by the head between the thumb and forefinger before

insertion into containers and labeled with the field collection numbers. Founding of the

geckos provide enough data on their ecology, such as the foraging behaviour,

microhabitat and the time of activity. The following data were recorded during the

sampling session:

1) Species – identified using external morphological features following Das (2004).

2) Time – encounter time (0000 hours) for each gecko.

3) Height – the vertical distance (in meters) from the substrate to where a gecko was

first observed.

4) The microhabitat-dark, shade or light.

Some species were quite common, such as Hemidactylus platyurus and Gehyra mutilata

whereas others were difficult to acquire in large numbers either because of restricted

habitat requirement or an apparent rarity. Specimen identification was done by Prof. Dr.

Indraneil Das and followed by referencing to the series of voucher specimens to confirm

the identities. The snout-vent lengths were measured to identify their maturity.

Specimens were measured using a ruler (to the nearest mm) and weighed with an

electronic-weight balance (to the nearest gm).

3.3 Stomach Content Analysis

Preserved specimens were dissected for stomach contents observation, in order to

compare diets between species. They were subsequently preserved in the ethanol before

long-term storage in formalin. All stomach contents were preserved in ethanol and

10

observed under an Olympux SZX9 microscope for identifications of food items

recovered. I used the work of Bland (1978), How to Know the Insects, for identification

of stomach contents. Prey in the stomachs were counted individually and recorded in the

data sheet. There are six successful type of prey identified, which are Hymenoptera,

Ants, Diptera, Isoptera, Spider and Indeterminate for the unrecognized stomach content.

Ants were separated from order Hymenoptera due to the abundance of hymenoptera in

stomach contents.

3.4 Data Analysis

Data analysis formulae adopted from other studies on resource partitioning and method

of measuring the overlap and niche breadth (Hulbert, 1978; Pianka, 1974; Das, 1996).

3.4.1 Dominance of Food Items

To examine the degree of dominance food items in stomach samples, the Berger-Parker

Diversity Index was used:

Equation 1

d=

,

Where N is the total number of individuals and , the number of individuals in the

most abundant resource type.

3.4.2 Niche Breadth

To quantify the variety of resources exploited by different species (niche breadth), the

diversity index of Simpson (1949), were used:

11

Equation 2

,

Where is the proportion of the th resource category used.

4.3.3. Standardized Niche Breadth

Standardized of niche breadth (B) of each species express it on a scale 0 to 1.0 using

Hurbert’s (1978) standardized niche breadth formula:

Equation 3

Where B is niche breadth and N is the total number of spatial type for the species of

interest.

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4.3.4 Niche Overlap

Niche overlap between the species will be calculated by using a symmetric version of

Mac Arthur and Levin’s (1967) equation:

Equation 4

Ojk=Okj=

Where Pi and Pik are the proportions of the resource used by the and the

species, respectively. It cannot generate values less than zero or greater than one.

Dietary analyses are based on ordinal level of prey identification. Computations of niche

breadths, niche overlaps and dominance were made from data after compilation into a

rectangular m by n matrix that indicates the rate of utilization of each m discrete resource

type (food, time or microhabitat) by n gecko’s species.

3.4.5 Cluster analysis

Cluster analysis was performed using Multi-Variate Statistical Package Version 3.13,

MSVP (Kovach, 2002). The agglomerative hierarchical clustering method was

conducted to generate dendrogram, utilising unweighted pair-group method using

arithmetic averages approach. The programme also was set to generate the similarity

matrix of the calculation. All figures in the following steps are referred in Appendix 3.

i. MSVP programme for Windows was launched. The file contains cluster data

was loaded and a window shows an open file with total variables and samples

or cases appeared.

13

ii. ii. In the analyses menu, cluster analysis was selected.

iii. iii. Cluster analysis options pop-up window appeared, and from the

dropdown list of clustering method, UPGMA was selected. For similarity or

distance, I selected the interest index from the dropdown list, e.g., Euclidean.

I clicked OK to continue

iv. iv. Next, the output data results were generated in two windows- MSVP

Results and Graphs. The output was saved as text and JPEG files.

14

CHAPTER 4

RESULTS

4.1 Species Abundance

Hemidactylus platyurus showed the highest number of individuals collected during the

sampling, followed by Gehyra mutilata. Based on the observation along the sample

collection, Hemidactylus platyurus is the most sighted individuals and easier to catch,

while Gekko monarchus are the rarest species and hardest to find.

Table 1: Relative Frequencies of Samples

SPECIES Total Weight(Mean)(g) SVL (Mean)

(mm)

H. platyurus 15 2.85 71.12

H. frenatus 10 3.87 48.62

Geh. mutilata 11 3.00 53.69

Gek. monarchus 10 2.07 38.70

Figure 1: Frequency occurrences of each species in UNIMAS campus.

32.61%

21.74% 23.91%

21.74%

0%

5%

10%

15%

20%

25%

30%

35%

H. platyurus H. frenatus Geh.mutilata Gek. monarchus

Num

ber

of

Ind

ivid

ual

s

Species

Total Species Collected in UNIMAS campus