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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
Bachelor of Science with Honours
(Animal Resource Science and Management)
2013
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
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
ii
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
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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…………………………………………………………………..
v
36
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
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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
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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
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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.
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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
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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.
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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
4
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.
5
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,
8
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
9
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:
10
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.
12
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.
13
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
Total Species Collected in UNIMAS campus
35%
32.61%
Number of Individuals
30%
25%
23.91%
21.74%
21.74%
20%
15%
10%
5%
0%
H. platyurus
H. frenatus
Species
Geh.mutilata
Gek. monarchus
Figure 1: Frequency occurrences of each species in UNIMAS campus.
14