Allometry Analysis of Fiddler Crabs Uca forcipata and U. dussumieri (Crustacea: Decapoda) in the West of Tanjung Jabung Jambi
ALLOMETRY ANALYSIS OF FIDDLER CRABS Uca forcipata AND U. dussumieri
(Crustacea: Decapoda) IN THE WEST OF TANJUNG JABUNG JAMBI
TIA WULANDARI
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2015
STATEMENT ABOUT THESIS
I hereby declare that thesis entitled Allometry Analisys of Fiddler Crabs Uca
forcipata and U. dussumieri (Crustacea: Decapoda) in the West of Tanjung
Jabung Jambi is original result of my own research supervised under advisory
committee and has never been submitted in any form at any institution before. All
information from other authors cited here are mentioned in the text and listed in the
reference at the end part of the thesis.
Bogor, May 2015
Tia Wulandari
G352130221
RINGKASAN
TIA WULANDARI. Analisis Allometri Kepiting Biola Uca forcipata dan U.
dussumieri (Crustacea: Decapoda) di Tanjung Jabung Barat Jambi. Dibimbing
oleh BAMBANG SURYOBROTO dan BERRY JULIANDI.
Kepiting biola jantan dewasa memiliki seksual dimorfisme yaitu salah satu
capitnya tumbuh lebih cepat dari capit lainnya. Kondisi ini menunjukkan bentuk
tubuh asimetri. Capit besar dapat berada pada bagian kanan (dekstral) atau bagian
kiri (sinistral) tubuh. Capit besar dan capit kecil pada Uca memiliki fungsi yang
berbeda. Capit besar berfungsi sebagai armamen, yaitu untuk bertarung dengan
individu jantan lainnya dalam memperebutkan teritori dan individu betina; capit
besar juga berfungsi sebagai ornamen, yaitu untuk menarik perhatian individu
betina. Capit kecil baik pada individu jantan maupun individu betina berfungsi
sebagai alat makan.
Studi mengenai asimetri dilakukan di Tanjung Jabung Barat Jambi,
Indonesia dari Agustus 2014 sampai Februari 2015. Jumlah sampel (individu)
yang digunakan dalam penelitian ini adalah 153. Terdiri dari dua spesies, yaitu 89
individu Uca forcipata dan 64 individu U. dussumieri.
Frekuensi handedness (posisi capit yang lebih besar) dari masing-masing
spesies pada masing-masing stasiun seimbang antara right-handed dan lefthanded (p-value 0.05; chi-square test). Analisis alometri dilakukan untuk melihat
kovariasi dari kedua capit, relatif terhadap perbedaan ukuran tubuh menggunakan
analisis bivariat. Lebar karapas (CRW) digunakan sebagai estimasi ukuran tubuh
karena paralel dengan hipotesis alometri positif dari pertumbuhan capit besar.
Panjang karapas (CRL) menunjukkan pola pertumbuhan alometri negatif terhadap
CRW. Capit besar menunjukkan pola pertumbuhan alometri positif dan capit kecil
menunjukkan pola pertumbuhan isometri untuk kedua spesies. Pertumbuhan yang
tidak seimbang pada kedua capit mengarahkan pada bentuk tubuh asimetri.
Kata kunci: Antisimetri, Asimetri, Dimorfisme seksual, Pola pertumbuhan, Uca
SUMMARY
TIA WULANDARI. Allometry Analysis of Fiddler Crabs Uca forcipata and U.
dussumieri (Crustacea: Decapoda) in the West of Tanjung Jabung Jambi.
Supervised by BAMBANG SURYOBROTO and BERRY JULIANDI.
Adult male of fiddler crabs have sexual dimorfism that one of cheliped grow
faster than the other. This condition leads to asymmetrical body pattern. Enlarged
cheliped can be on right (dextral) or left side (sinistral) of the body. Major and
minor cheliped in Uca have different function. Major cheliped use as armament,
for fighting with another male for territory and female; and as ornament for
female attractor. Minor cheliped in male and female have same function, that as a
feeding tools.
A study of asymmetry was conducted in the West of Tanjung Jabung Jambi,
Indonesia from early August 2014 to the end of February 2015. The number of
samples (individuals) used in this research was 153. That consisted of two species,
in the following quantities 89 individu of Uca forcipata and 64 individu of U.
dussumieri.
The frequency of handedness (position of enlarged cheliped) for either
species at each sampling station was equal for right-handed and left-handed (pvalue 0.05; chi-square test). Allometry analysis was done to study the covariation
of chelipeds, relative to different body sizes using bivariate analysis. Carapace
width (CRW) was used as a proxy for body size because it varies in parallel with
the hypothesized positive allometry of the major cheliped. Carapace length (CRL)
showed a negative allometrical growth pattern relative to CRW. The major
cheliped showed positive allometry, and the minor cheliped showed isometry, in
both species. This might have caused the growth imbalance between chelipeds
that leads to the asymmetry of body shape.
Keywords : Antisymmetry, Asymmetry, Growth pattern, Sexual dimorphism, Uca
© Copy Right by IPB, 2015
All rights reserved
It is prohibited to cite all or a part of this thesis without referring to and
mentioning the source. Citation is permitted for the purpose of education, research,
scientific paper, report, or critism writing only; and it does not defame the name
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It is prohibited to republish and reproduce all or a part of this thesis without
permission from Bogor Agricultural University.
ALLOMETRY ANALYSIS OF FIDDLER CRABS Uca forcipata AND U. dussumieri
(Crustacea: Decapoda) IN THE WEST OF TANJUNG JABUNG JAMBI
TIA WULANDARI
A Graduate Thesis
in partial fulfilment of Master Science degree in Animal Biosciences
Faculty of Mathematics and Natural Science
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2015
Examiners: Dr. Yusli Wardiatno, M.Sc
ENDORSEMENT PAGE
: Allometry Analysis of Fiddler Crabs Uca forcipata and
U. dussumieri (Crustacea: Decapoda) in the West of Tanjung
Jabung Jambi
Name
: Tia Wulandari
Student ID : G352130221
Title
Approved by,
Supervisory Committee
Dr Bambang Suryobroto
Chair
Dr Berry Juliandi
Member
Agreed by,
Chair of Major of Animal Biosciences
Dean of Graduate School,
Dr Ir R. R. Dyah Perwitasari
Dr Ir Dahrul Syah, MSc.Agr
Examination date: May 19th, 2015
Date of Completing Studies:
PREFACE
The title of this thesis is Allometry Analysis of Uca forcipata and U.
dussumieri (Genus:Uca) in the West of Tanjung Jabung Jambi. The samples of
these research took from the west of Tanjung Jabung Jambi. I want to send my
gratitude to my supervisor Dr Bambang Suryobroto and Dr Berry Juliandi for all
guidance and endcouragement as well as invaluable academic advices for the
whole period of my study and research, and to my examiner Dr. Yusli Wardiatno,
M.Sc. for the generous support and great discussion. Thank to Mr. Taharudin, Mr.
Mulyo and Rizki for their help throughout in the field; Mrs. Tini, Mrs. Dewi Citra
Murniati for their help in the laboratory. Thank to all people in Zoo Corner, BSH
2013, and special thank to my parents and my family, for their supports for my
study. Therefore, above all, I thank God Allah SWT for His almighty.
Bogor, May 2015
Tia Wulandari
CONTENTS
LIST OF TABLES
vi
LIST OF FIGURES
vi
INTRODUCTION
1
MATERIALS AND METHOD
Sample
Data Analysis
1
1
2
RESULT AND DISCUSSION
Results
Discussion
4
4
7
CONCLUSION
9
REFFERENCES
9
APPENDIXES
11
CURRICULUM VITAE
14
LIST OF TABLES
1
2
3
4
5
Frequency of handedness
Growth pattern comparison of CRL and CRW
Elevation regression line value of U. forcipata and U. dussumieri
Allometry analysis of U. forcipata and U. dussumieri
Allometry analysis of handedness U. forcipata and U. dussumieri
4
5
6
6
6
LIST OF FIGURES
1 Schematic measurement of carapace
2 Comparison of carapace length (CRL) and carapace width (CRW)
(a) Uca forcipata (b) U. dussumieri
3 Schematic measurement of cheliped
4 Antisymmetry in U. forcipata and U. dussumieri
5 Growth pattern comparison between traits in Genus Uca
6 Growth pattern comparison between traits in (A) right-handed and
(B) left-handed of U. forcipata
7 Growth pattern comparison between traits in (A) right-handed and
(B) left-handed U. dussumieri
3
3
3
4
5
7
7
LIST OF APPENDIX
1 Location of research sampling
2 Linear regression equation between body features
12
13
INTRODUCTION
Fiddler crabs (Uca spp.) are intertidal crabs that show sexual dimorphism
during the adult stage. The sexual dimorphism manifests as asymmetry in male
chelipeds, while the female remains symmetric (Rosenberg 2001). Adult males
have one enlarged cheliped, with the other remaining ‘normal’. The major
cheliped can be twice the size of the carapace. This cheliped is thought to be used
for armament and ornament, while the minor cheliped is used for feeding in the
male as are both chelipeds in the female (Rosenberg 2002, Murniati 2009).
In fiddler crabs, the enlarged cheliped can be on the right (dextral) or left
(sinistral) side of the body. This random asymmetry within a population is known
as antisymmetry (Valen 1962). In antisymmetry, development of asymmetrical
traits is almost never inherited and is triggered by the external environment
(Vanberg and Costlow 1966; Yamaguchi 1977; Palmer 2004; Palmer 2012).
Selection pressure in a population could affect the dominance of right or left
enlarged chelipeds (Palmer 1996; Croll and McClintock 2002; Rosenberg 2002).
Many traits that are associated with combat or aids to courtship, evolved by sexual
selection; for example, in fiddler crabs the enlarged cheliped is used as weapon in
male combat, and for courtship display to attract females (Boundriansky and Day
2003).
Asymmetry of bilateral features develops through an allometrical growth
mechanism. Huxley (1924) coined the elementary law of relative growth,
expressed by
y= βxα ……………….…………………………(1)
where x and y are bodily measurements, and β and α are constants. Modern
concept of allometry is based on the fact that various organs grow at different
rates relative to the standardized size of an organism (Klingenberg 1996; Gebo
1993). When the shape of an organism conforms to predictions based on
maintaining the same shape over a range of sizes, it is said to be in an isometrical
growth pattern; when the shape changes following changes in size, it is allometric
(Claude 2008).
Although asymmetry has been extensively observed in genus Uca,
quantification and the cause of antisymmetry in this genus - especially Uca
forcipata (Adams and White, 1848) and U. dussumieri (Milne-Edwards, 1852) –
has remained unknown. This present study reports that the frequency of lefthanded or right-handed in cheliped of U. forcipata and U. dussumieri is equal and
the handedness occurs in an antisymmetrical way. An asymmetrical body shape is
caused by the faster growth of one cheliped relative the other.
MATERIALS AND METHOD
Sample
This research was conducted between August 2014 and February 2015.
Adult male fiddler crabs which had a carapace width (CRW) of more than 15mm
2
were taken from an area in the West of Tanjung Jabung, Jambi, Indonesia. Crabs
of this size have already developed asymmetrical chelipeds. They were collected
from two stations with different types of habitat 0o48’44.2”S-103o29’2.8”E: sandy
clay substrate and 0o49’3.1”S-103o28’48.7”E: clay substrate; (appendix 1).
Specimens were collected from 08.00-15.00 WIB (low tide and sunshine). The
sample was identified at the Museum Zoologicum Bogoriense (MZB) in Cibinong.
Sample identification was based on criteria established by Crane (1975).
Identification was taken to species level. The number of samples used in this
research was 153 individuals: comprising two species, in the following quantities:
89 individu of Uca forcipata and 64 individu of U. dussumieri.
Data Analysis
Frequency of either handedness
The frequency of ‘right-handed’ and ‘left-handed’ individuals at each
station was compared using the chi-square test (Agresti 2007).
Allometry analysis
Following Huxley’s morphological law (Huxley 1924), allometry analysis
was carried out, in order to study the covariation of size of major and minor
chelipeds (y) relative to different body sizes (x). When α=1, y grows in an
isometric way relative to x; that is, increases of one unit measurement of x will be
followed by increases of the same amount of y. When α≠1, the rate of growth of y
is longer (allometry positive) or smaller (allometry negative) than that of x.
In this study, the body size was estimated using carapace size. Carapace
width (CRW, the distance between two antero-lateral angles in the carapace) was
the most representative of overall size of the crabs (Martins and Masunari 2013).
In a preliminary allometrical comparison (see statistical analysis below) of the
respective growths of CRW and carapace length (CRL, the distance between front
and intestinal of carapace) (Figure 1), it was shown that CRW grew faster than
CRL (Figure 2). Therefore CRW was used as an estimate of body size, as it varies
in parallel with the hypothesized positive allometry of major cheliped.
Cheliped size was measured in terms of length and width. According to
Crane (1975) cheliped length is the distance from the tip of the pollex to the base
of the connection between carpus and manus: (L) for length of the major cheliped,
and (L1) for length of the minor cheliped. Cheliped width is the distance from the
top of the joint between dactyl and manus, to the depression at the base of the
pollex: (W) for width of the major cheliped, and (W1) for width of the minor
cheliped (Figure 3). All measurements were done three times and the average
values were used in the analysis (Rosenberg 1997; Rosenberg 2002; Hirose et al.
2010).
3
3.5
B
3.0
A
2.0
2.0
2.5
2.5
log(CRL)
log(CRL)
3.0
3.5
Figure 1 Schematic measurement of carapace. CRL (carapace length), CRW
(carapace width).
2.6
2.8
3.0
3.2
log(CRW)
3.4
3.6
3.8
2.6
2.8
3.0
3.2
3.4
3.6
3.8
log(CRW)
Figure 2 Comparison of carapace length (CRL) and carapace width (CRW) (a)
Uca forcipata (b) U. dussumieri. In U. forcipata (α=0.96, H0=1,
p=0.01) and U. dussumieri (α=0.93, H0=1 p=1.6x10-6) indicate CRW
grow faster than CRL.
Figure 3 Schematic measurement of cheliped. (A) cheliped length; (B) cheliped
width.
Statistical analysis
Huxley’s equation can be linearized by using logarithms of the original
measurements
log y = log β + α log x …………………………..(2)
4
This equation can be used to describe allometrical growth patterns in respect
of chelipeds and carapace width. The constancy of α is an important parameter in
the assessment of the static allometry of adult crabs. The regression model II was
chosen to find the regression line (Sokal and Rohlf 1969), because this model
takes into consideration the inherent variability of both the carapace and the
chelipeds. This is in contrast to model I, where one of the variables should be
measured without error. The estimate and confidence intervals for the slope of the
model II regression line were measured using the standardised major axis (SMA)
method (Sokal and Rohlf 1969). The Standardised Major Axis Tests and Routines
(SMATR) software provides tools for the estimation, and inferences about
regression lines relative to hypothetical isometric lines (Warton et al. 2012).
RESULTS AND DISCUSSION
Results
Frequency of either handedness
In adult male genus Uca, one of the cheliped grew faster than the other. The
enlarged cheliped can be found on right or left side of the body. This phenomena
is called antisymmetry (Figure 4). This study shows that the frequency of
handedness in U. forcipata and U. dussumieri was equal, and occurred in a
random position (Table 1).
Figure 4 Antisymmetry in (A) U. forcipata and (B) U. dussumieri
Table 1 Frequency of handedness
No
1
2
3
Species
Station
U. forcipata
I
U. forcipata
II
U. dussumieri
II
Total
Right-handed
36
6
36
78
Left-handed
38
9
28
75
p-value
0.8162
0.4386
0.3173
P≤0.05, Frequency of right-handed and lef-handed is significantly different. H0=50:50
5
Allometry analysis
In this study, the asymmetrical growth pattern of major and minor chelipeds
was compared by reference to carapace size. Comparison of CRL and CRW in
Uca forcipata and in U. dussumieri indicated in faster growth of CRW than CRL
and parallel growth major and minor growth pattern than CRL (Table 2).
Table 2 Growth pattern comparison of CRL and CRW
Species
U. forcipata
U. dussumieri
N
89
64
Slope
0.9601498
0.9302653
P
0.01018878
1.640788e-06
Pattern
Allometry (-)
Allometry (-)
p ≤ 0.05 slope is significantly different from 1 (isometry). H0=1
5
Size comparison of body features in U. forcipata and U. dusumieri showed
asymmetry of body shape based on allometrical analysis. Result of analysis shows
that the major cheliped length (L) of U. dussumieri is longer than U. forcipata.
Differences of growth rate between major cheliped lenght (L) of U. forcipata and
U. dussumieri can be showed based on regression line (Figure 5). The y-intercept
value of regression line can be indicated the differences of growth rates.
Overlapping of upper limit and lower limit between two regression line leads to
parallel growth rates. Meanwhile, non-overlapping of upper limit and lower limit
between two regression line indicates non-parallel growth rates (Table 3).
L
3
L1
W1
1
2
log(TRAITS)
4
W
1
2
3
4
5
log(CRW)
Figure 5 Growth pattern comparison between traits in Uca forcipata (red circle)
and U. dussumieri (black circle); L (major cheliped length),W (major
cheliped width), L1 (minor cheliped length), W1 ( minor cheliped width).
6
Table 3 Elevation regression line value of U. forcipata and U. dussumieri
Traits
L
W
L1
W1
Elevation
-1.897593
-1.659258
-1.073495
-2.0793661
U. forcipata
Lower limit Upper limit
-2.203430 -1.591755
-1.928521 -1.389994
-1.230476 -0.916513
-2.279556 -1.879175
Elevation
-2.838938
-1.552041
-1.080059
-1.893872
U. dussumieri
Lower limit Upper limit
-3.412637 -2.265238
-2.067133 -1.036949
-1.231496 -0.928622
-2.111192 -1.676551
L (major cheliped length),W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width);
The analysis of the two sets of data was carried out. First, data for each
species, irrespective of handedness (Table 4); and second, data separated for righthanded and left-handed (Table 5). When the slope is significantly different from 1,
an allometric growth pattern (p ≤ 0.05) was indicated. The major cheliped shows
positive allometry, and the minor cheliped shows an isometric growth pattern,
with respect to CRW, for both of groups of data (Figures 6 and 7).
Table 4 Allometry analysis of U. forcipata and U. dussumieri
Measurement
Species
L
U. forcipata
U. dussumieri
W
U. forcipata
U. dussumieri
L1
U. forcipata
U. dussumieri
W1
U. forcipata
U. dussumieri
N
89
64
89
64
88
63
88
63
Slope
1.705365
1.973034
1.327799
1.267016
1.025352
1.042195
0.971302
0.898517
Intercept
-1.897593
-2.838938
-1.659258
-1.552041
-1.073495
-1.080059
-2.0793661
-1.893872
P
Pattern
0
Allometry (+)
0
Allometry (+)
2.515765e-13 Allometry (+)
0.0002343904 Allometry (+)
0.3217848
Isometry
0.06348424
Isometry
0.3916357
Isometry
0.9663027
Isometry
L (major cheliped length) ,W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width); p ≤ 0.05 slope is significantly different from 1 (isometry); H0=1.
Table 5 Allometry analysis of handedness U. forcipata and U. dussumieri
Measurement Species
L
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
W
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
L1
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
W1
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
Handedness
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
n
43
46
36
28
43
46
36
28
43
45
35
28
43
45
35
28
Slope
1.790828
1.604728
2.007487
1.935153
1.348406
1.303960
1.310316
1.216952
1.014016
1.038193
1.059596
1.023603
0.9455919
1.038193
0.8431879
0.9509932
P
0
3.330669e-16
1.498801e-14
5.734546e-11
1.939273e-07
8.41641e-07
0.002898705
0.03531351
0.6566541
0.3581239
0.03803067
0.4698372
0.2862765
0.9974495
0.001756304
0.3438264
Pattern
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Isometry
Isometry
Allometry (+)
Isometry
Isometry
Isometry
Allometry (-)
Isometry
L (major cheliped length) ,W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width); p ≤ 0.05 slope is significantly different from 1 (isometry); H0=1.
7
A
B
4
W(+)
3
L1
L(+)
2
L(+)
log(TRAITS)
3
L1(+)
2
log(TRAITS)
4
W(+)
W1(-)
1
1
W1
1
2
3
4
1
2
log(CRW)
3
4
log(CRW)
Figure 6 Growth pattern comparison between traits in (A) right-handed and (B)
left-handed of U. forcipata. L (major cheliped length), W (major
cheliped width), L1 (minor cheliped length), W1 (minor cheliped
width). (+) indicate positive allometry and (-) indicate negative
allometry.
B
A
3
W1
1
W1
L1
2
2
L1
W+
log(TRAITS)
3
W+
1
log(TRAITS)
4
L+
4
L+
1
2
3
4
log(CRW)
1
2
3
4
log(CRW)
Figure 7 Growth pattern comparison between traits in (A) right-handed and (B)
left-handed U. dussumieri. L (major cheliped length), W (major
cheliped width), L1 (minor cheliped length), W1 ( minor cheliped
width). (+) indicate positive allometry and (-) indicate negative
allometry.
Discussion
Frequency of either handedness
In the adult male of genus Uca, one of the chelipeds grew faster than the
other. The enlarged cheliped can be found on the right or left side of the body.
This phenomenon is called antisymmetry. The relative frequency of either
handedness is useful as an indicator of grouping within genus Uca. In most
populations of Uca, the ratio of right-handed to left-handed is 50:50 (Crane 1975;
Backwell et al. 2007; Martins and Masunari 2013). U. forcipata and U.
dussumieri, which were identified as belonging to the Deltuca subgenera, show
8
equal frequency of either handedness (p≤0.05). Jones and George (1982) also
found that U. dussumieri had equal proportions of right-handed and left-handed
males. In contrast, another study in southeast Sulawesi found 14 left-handed and
two right-handed males of U. dussumieri (Weis and Weis 2004). In Thallasuca,
another subgenera of Uca showed a predominance of right-handed males (Jones
and George 1982).
Development of antisymmetrical traits is almost never inherited.
Antisymmetrical development is triggered by the external environment (Vanberg
and Costlow 1966; Yamaguchi 1977; Palmer 2004; Palmer 2012). The major
cheliped in genus Uca develops in parallel with sexual maturation. It develops for
the first time in the seventh juvenile stage of juvenile, although there is no
obvious sign of asymmetry at that stage (Pralon and Negreiros-Fransozo 2007;
Vieira 2010). Sexual maturation is not the only possible factor however; loss of
one cheliped before the immature stage, also determined handedness. It has not
been established whether handedness in Uca is caused by genetic factors, or an
imbalance differentiation during growth because of the loss of one claw (Vanberg
and costlow 1966; Yamaguchi 1977).
The major cheliped is used for combat and the attraction of mates. When
this cheliped is lost, it will grow back on the same side. The respective
handedness in the male Uca could affect fight activity. In one population, the
choice of fighting a rival with the same or different handedness can affect fighting
tactics. Right-handed males are significantly more likely to fight than left-handed
males. When left-handed males do fight, they are less likely to win (Backwell et
al. 2007).
Allometry analysis
Standard growth of body dimensions between individuals in the same
species or different species has biological consequences (Pralon and NegreirosFransozo 2007). In this study, asymmetrical growth patterns of chelipeds were
compared with carapace size. CRW was considered the best predictor, relative to
other body dimensions, and considered an appropriate proxy for body size since it
is most representative of the overall size of crabs (Araujo et al. 2012; Martins and
Masunari 2013).
Major cheliped length in U. dussumieri is longer than in U. forcipata. The
propudus and the dactilus in U. dusssumieri are both slimmer than in U. forcipata.
These factors caused a larger total length of cheliped in U. dussumieri than the
thicker one found in U. forcipata. The relative dimensions of cheliped size can be
caused by genetic factors, but in some cases can be influenced by environmental
factors (Murniati 2010). Based on the major cheliped length (L) of U. dussumieri
longer than U. forcipata, further analysis separated these two species (interspecies
analysis).
The major cheliped grows allomertical positive and the minor cheliped
grows isometry with respect to CRW (appendix 2). Generally within a species, the
major claw growth exhibits positive allometry, while the minor claw grows
isometrically (Rosenberg 2002). The growth pattern in male and female of genus
Uca indicates their sexual functions; disproportionate growth of only one of the
chelipeds in males, and increase of abdomen size in females (Araujo et al. 2012).
An imbalance in the relative sizes of major and minor chelipeds, shows an
9
asymmetrical pattern in U. forcipata and U. dussumieri. Isometry shows a linear
regression of 45o and indicates similar proportions of size growth between
predictor and response. Meanwhile, allometry leads to a linear regression with an
angel ≠ 45o; more than 45o for positive allometry, and less than 45o for negative
allometry.
CONCLUSION
The frequencies of handedness in U. forcipata and U. dussumieri were equal
for right-handed and left-handed. The occurrence of major chelipeds on either side
in U. forcipata and U. dussumieri shows an antisymmetrical growth pattern.
Major chelipeds showed positive allometry and minor chelipeds showed isometry
for both species. This might have caused the growth imbalance between chelipeds
that leads to the asymmetry of body shape.
REFERENCES
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NY: University of Florida.
Araujo MSL, Coelho PA, Castiglioni DA. 2012. Relative growth and
determination of morphological sexual maturity of the fiddler crab Uca
thayeri Rathbun (Crustacea, Ocypodidae) in two mangrove areas from the
Brazilian tropical coast. PanamJAS.7:156-170.
Backwell PRY, Matsumasa M, Double M, Roberts A, Murai V, Keogh JS,
Jennions MD. 2007. What are the consequences of being left-clawed in a
predominantly right-clawed fiddler crab?. Proc R Soc B: Biol
Sci.274:2723–2729.
Boundriansky R, Day T. 2003. The Evolution of Static Allometry in Sexually
Selected Traits. Evol.57: 2450-2458.
Claude J. 2008. Morphometrics in R. France, FR: University de Montpellier II.
Crane J. 1975. Fiddler Crabs of The World, Ocypodidae: genus Uca. Princeton,
US: Princeton University Pr.
Croll GA, McClintock JB. 2002. An analysis of cheliped asymmetry in three
species of fiddler crabs. Gulf Mex Sci.20: 106-109.
Gebo DL. 1993. Postcranial Adaptation in Nonhuman Primates. DeKalb, US:
Northern Illinois University Press.
Hirose GL, Junior EAB, Fransozo MLN. 2010. Post-lrval morphology, and
development of Uca cumulata, 1943 (Crustacea, Decapoda, Ocypodidae)
under laboratory conditions. Invertebr Reprod Dev. 54: 95-109.
Huxley JS. 1924. Constant differential growth-ratios and their significance.
Nature.114:895-896.
Jones DS, George RW. 1982. Handedness in fiddler crabs as an aid in taxonomic
grouping of the Genus Uca (Decapoda, Ocypodidae). Crustaceana.
43:100-102.
10
Klingenberg PC. Multivariate Allometry. New York, US: Plenum Press; 1996.
Martins SB, Masunari S. 2013. Relative growth in the fiddler crab Uca
uruguayensis Nobili, 1901 (Brachyura, Ocypodidae) from Garças River
mangrove, Guaratuba Bay, southern Brazil. Nauplius. 21: 35-41.
Murniati DC. 2009. Perbandingan luas tutupan spoon tiped setae maksiliped
kedua pada Uca spp. (Brachyura: Ocypodidae). Fauna Ind. 18:1-8.
Murniati DC. 2010. Pola dominansi capit pada Uca spp. (Decapoda: Ocypodidae).
J Biol Sci Res.16:15-20.
Palmer AR. 1996. From symmetry to asymmetry: Prhylogenetic patterns of
asymmetry variation in animals and their evolutionary significance. Proc
Natl Acad Sci. 93:14279–14286.
Palmer AR. 2004. Symmetry Breaking and the Evolution of Development.
Science.36:828-833.
Palmer AR. 2012. Developmental origins of normal and anomalous random rightleft asymmetry; lateral inhibition versus developmental error in a threshold
trait. Contrib Zool. 81: 111-124.
Pralon BGN, Nigreiros-Fransozo MC. 2007. Relative growth and morphological
sexual maturity of Uca cumulate (Crustacea: Decapoda: Ocypodidae) from
tropical Brazilian mangrove population. J Mar Biol Assoc U.K. 83: 569574.
Rosenberg MS. 1997. Evolution of shape differences between the major and
minor chelipeds of Uca pugnax (decapoda: Ocypodidae). J Crust Biol.17:
52-59.
Rosenberg MS. 2001. The systematics and taxonomy of fiddler crabs: a
phylogeny of the genus Uca. J Crust Biol. 21: 839–869.
Rosenberg MS. 2002. Fiddler crab claw shape variation: a geometric
morphometric analysis across the genus Uca (Crustacea: Brachyura:
Ocypodidae). Biol J Linnean Soc.75:147-162.
Sokal RR, Rohlf FJ. 1969. Biometry, The Principles and Practice of Statistics in
Biological Research. 3th ed. New York, US: State University of New York
at Stony Brook.
Valen LV. 1962. A Study of Fluctuating Asymmetry. Evolution. 16: 125-142.
Vanberg FJ, Costlow JD. 1966. Handedness in fiddler crabs (Genus Uca).
Crustaceana.11: 61-64.
Vieira RRR, Pinho GLL, Rieger PJ. 2010. Juvenile development of Uca (Minuca)
Burgersi Holthuis, 1967 (Crustacea, Brachyura, Ocypodidae) in the
laboratory. Atlantica (Rio Grande). 32: 59-70.
Warton DI, Remko AD, Daniel SF, Sara T. 2012. SMATR 3 – an R package for
estimation and inference about allometric lines. Methods Ecol Evol. 3:
257–259.
Weis JS, Peddrick W. 2004. Behavior of four species of fiddler crabs, genus Uca,
in southeast Sulawesi, Indonesia. Hydrobiologia. 34: 47-58.
Yamaguchi T. 1977. Studies of the handedness of the fiddler crab Uca lactea. Biol
Bull. 152: 424-436.
11
12
11
APPENDIXES
Appendix 1 Location of research sampling
12
13
Appendix 2 Linear regression equation between body features (CRW is predictor) in Uca forcipata and U. dussumieri
Relation between
L vs CRW
W vs CRW
L1 vs CRW
W1 vs CRW
Species
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
y = ax+b
L = 1.705365 CRW - 1.897593
L = 1.973034 CRW - 2.838938
W = 1.327799 CRW - 1.659258
W = 1.267016 CRW - 1.552041
L1 = 1.025352 CRW - 1.073495
L1 = 1.042195 CRW - 1.080059
W1 = 0.971302 CRW - 1.080059
W1 = 0.898517 CRW - 1.080059
p ≤ 0.05
p ≤ 0.05
p ≤ 0.05
p ≤ 0.05
p ≥0.05
p ≥0.05
p ≥0.05
p ≥0.05
Slopes
(Allometry)
(Allometry)
(Allometry)
(Allometry)
(Isometry)
(Isometry)
(Isometry)
(Isometry)
Intercepts
Non-parallel
Parallel
Parallel
Parallel
14
CURRICULUM VITAE
Author was born in Jambi on December 22nd, 1990. Author is the third
child of five from the parents, Aminursan and Lily Handayani. In 2008 author
studied in Jambi University, Faculty of Education and Teacher Training, in major
of Biology education and graduated from Jambi University in 2012. In 2013
author got BPPDN scholarship from DIKTI and enrolled in the Graduate School,
Major of Animal Biosciences, Bogor Agricultural University.
(Crustacea: Decapoda) IN THE WEST OF TANJUNG JABUNG JAMBI
TIA WULANDARI
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2015
STATEMENT ABOUT THESIS
I hereby declare that thesis entitled Allometry Analisys of Fiddler Crabs Uca
forcipata and U. dussumieri (Crustacea: Decapoda) in the West of Tanjung
Jabung Jambi is original result of my own research supervised under advisory
committee and has never been submitted in any form at any institution before. All
information from other authors cited here are mentioned in the text and listed in the
reference at the end part of the thesis.
Bogor, May 2015
Tia Wulandari
G352130221
RINGKASAN
TIA WULANDARI. Analisis Allometri Kepiting Biola Uca forcipata dan U.
dussumieri (Crustacea: Decapoda) di Tanjung Jabung Barat Jambi. Dibimbing
oleh BAMBANG SURYOBROTO dan BERRY JULIANDI.
Kepiting biola jantan dewasa memiliki seksual dimorfisme yaitu salah satu
capitnya tumbuh lebih cepat dari capit lainnya. Kondisi ini menunjukkan bentuk
tubuh asimetri. Capit besar dapat berada pada bagian kanan (dekstral) atau bagian
kiri (sinistral) tubuh. Capit besar dan capit kecil pada Uca memiliki fungsi yang
berbeda. Capit besar berfungsi sebagai armamen, yaitu untuk bertarung dengan
individu jantan lainnya dalam memperebutkan teritori dan individu betina; capit
besar juga berfungsi sebagai ornamen, yaitu untuk menarik perhatian individu
betina. Capit kecil baik pada individu jantan maupun individu betina berfungsi
sebagai alat makan.
Studi mengenai asimetri dilakukan di Tanjung Jabung Barat Jambi,
Indonesia dari Agustus 2014 sampai Februari 2015. Jumlah sampel (individu)
yang digunakan dalam penelitian ini adalah 153. Terdiri dari dua spesies, yaitu 89
individu Uca forcipata dan 64 individu U. dussumieri.
Frekuensi handedness (posisi capit yang lebih besar) dari masing-masing
spesies pada masing-masing stasiun seimbang antara right-handed dan lefthanded (p-value 0.05; chi-square test). Analisis alometri dilakukan untuk melihat
kovariasi dari kedua capit, relatif terhadap perbedaan ukuran tubuh menggunakan
analisis bivariat. Lebar karapas (CRW) digunakan sebagai estimasi ukuran tubuh
karena paralel dengan hipotesis alometri positif dari pertumbuhan capit besar.
Panjang karapas (CRL) menunjukkan pola pertumbuhan alometri negatif terhadap
CRW. Capit besar menunjukkan pola pertumbuhan alometri positif dan capit kecil
menunjukkan pola pertumbuhan isometri untuk kedua spesies. Pertumbuhan yang
tidak seimbang pada kedua capit mengarahkan pada bentuk tubuh asimetri.
Kata kunci: Antisimetri, Asimetri, Dimorfisme seksual, Pola pertumbuhan, Uca
SUMMARY
TIA WULANDARI. Allometry Analysis of Fiddler Crabs Uca forcipata and U.
dussumieri (Crustacea: Decapoda) in the West of Tanjung Jabung Jambi.
Supervised by BAMBANG SURYOBROTO and BERRY JULIANDI.
Adult male of fiddler crabs have sexual dimorfism that one of cheliped grow
faster than the other. This condition leads to asymmetrical body pattern. Enlarged
cheliped can be on right (dextral) or left side (sinistral) of the body. Major and
minor cheliped in Uca have different function. Major cheliped use as armament,
for fighting with another male for territory and female; and as ornament for
female attractor. Minor cheliped in male and female have same function, that as a
feeding tools.
A study of asymmetry was conducted in the West of Tanjung Jabung Jambi,
Indonesia from early August 2014 to the end of February 2015. The number of
samples (individuals) used in this research was 153. That consisted of two species,
in the following quantities 89 individu of Uca forcipata and 64 individu of U.
dussumieri.
The frequency of handedness (position of enlarged cheliped) for either
species at each sampling station was equal for right-handed and left-handed (pvalue 0.05; chi-square test). Allometry analysis was done to study the covariation
of chelipeds, relative to different body sizes using bivariate analysis. Carapace
width (CRW) was used as a proxy for body size because it varies in parallel with
the hypothesized positive allometry of the major cheliped. Carapace length (CRL)
showed a negative allometrical growth pattern relative to CRW. The major
cheliped showed positive allometry, and the minor cheliped showed isometry, in
both species. This might have caused the growth imbalance between chelipeds
that leads to the asymmetry of body shape.
Keywords : Antisymmetry, Asymmetry, Growth pattern, Sexual dimorphism, Uca
© Copy Right by IPB, 2015
All rights reserved
It is prohibited to cite all or a part of this thesis without referring to and
mentioning the source. Citation is permitted for the purpose of education, research,
scientific paper, report, or critism writing only; and it does not defame the name
and honour of Bogor Agricultural University.
It is prohibited to republish and reproduce all or a part of this thesis without
permission from Bogor Agricultural University.
ALLOMETRY ANALYSIS OF FIDDLER CRABS Uca forcipata AND U. dussumieri
(Crustacea: Decapoda) IN THE WEST OF TANJUNG JABUNG JAMBI
TIA WULANDARI
A Graduate Thesis
in partial fulfilment of Master Science degree in Animal Biosciences
Faculty of Mathematics and Natural Science
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2015
Examiners: Dr. Yusli Wardiatno, M.Sc
ENDORSEMENT PAGE
: Allometry Analysis of Fiddler Crabs Uca forcipata and
U. dussumieri (Crustacea: Decapoda) in the West of Tanjung
Jabung Jambi
Name
: Tia Wulandari
Student ID : G352130221
Title
Approved by,
Supervisory Committee
Dr Bambang Suryobroto
Chair
Dr Berry Juliandi
Member
Agreed by,
Chair of Major of Animal Biosciences
Dean of Graduate School,
Dr Ir R. R. Dyah Perwitasari
Dr Ir Dahrul Syah, MSc.Agr
Examination date: May 19th, 2015
Date of Completing Studies:
PREFACE
The title of this thesis is Allometry Analysis of Uca forcipata and U.
dussumieri (Genus:Uca) in the West of Tanjung Jabung Jambi. The samples of
these research took from the west of Tanjung Jabung Jambi. I want to send my
gratitude to my supervisor Dr Bambang Suryobroto and Dr Berry Juliandi for all
guidance and endcouragement as well as invaluable academic advices for the
whole period of my study and research, and to my examiner Dr. Yusli Wardiatno,
M.Sc. for the generous support and great discussion. Thank to Mr. Taharudin, Mr.
Mulyo and Rizki for their help throughout in the field; Mrs. Tini, Mrs. Dewi Citra
Murniati for their help in the laboratory. Thank to all people in Zoo Corner, BSH
2013, and special thank to my parents and my family, for their supports for my
study. Therefore, above all, I thank God Allah SWT for His almighty.
Bogor, May 2015
Tia Wulandari
CONTENTS
LIST OF TABLES
vi
LIST OF FIGURES
vi
INTRODUCTION
1
MATERIALS AND METHOD
Sample
Data Analysis
1
1
2
RESULT AND DISCUSSION
Results
Discussion
4
4
7
CONCLUSION
9
REFFERENCES
9
APPENDIXES
11
CURRICULUM VITAE
14
LIST OF TABLES
1
2
3
4
5
Frequency of handedness
Growth pattern comparison of CRL and CRW
Elevation regression line value of U. forcipata and U. dussumieri
Allometry analysis of U. forcipata and U. dussumieri
Allometry analysis of handedness U. forcipata and U. dussumieri
4
5
6
6
6
LIST OF FIGURES
1 Schematic measurement of carapace
2 Comparison of carapace length (CRL) and carapace width (CRW)
(a) Uca forcipata (b) U. dussumieri
3 Schematic measurement of cheliped
4 Antisymmetry in U. forcipata and U. dussumieri
5 Growth pattern comparison between traits in Genus Uca
6 Growth pattern comparison between traits in (A) right-handed and
(B) left-handed of U. forcipata
7 Growth pattern comparison between traits in (A) right-handed and
(B) left-handed U. dussumieri
3
3
3
4
5
7
7
LIST OF APPENDIX
1 Location of research sampling
2 Linear regression equation between body features
12
13
INTRODUCTION
Fiddler crabs (Uca spp.) are intertidal crabs that show sexual dimorphism
during the adult stage. The sexual dimorphism manifests as asymmetry in male
chelipeds, while the female remains symmetric (Rosenberg 2001). Adult males
have one enlarged cheliped, with the other remaining ‘normal’. The major
cheliped can be twice the size of the carapace. This cheliped is thought to be used
for armament and ornament, while the minor cheliped is used for feeding in the
male as are both chelipeds in the female (Rosenberg 2002, Murniati 2009).
In fiddler crabs, the enlarged cheliped can be on the right (dextral) or left
(sinistral) side of the body. This random asymmetry within a population is known
as antisymmetry (Valen 1962). In antisymmetry, development of asymmetrical
traits is almost never inherited and is triggered by the external environment
(Vanberg and Costlow 1966; Yamaguchi 1977; Palmer 2004; Palmer 2012).
Selection pressure in a population could affect the dominance of right or left
enlarged chelipeds (Palmer 1996; Croll and McClintock 2002; Rosenberg 2002).
Many traits that are associated with combat or aids to courtship, evolved by sexual
selection; for example, in fiddler crabs the enlarged cheliped is used as weapon in
male combat, and for courtship display to attract females (Boundriansky and Day
2003).
Asymmetry of bilateral features develops through an allometrical growth
mechanism. Huxley (1924) coined the elementary law of relative growth,
expressed by
y= βxα ……………….…………………………(1)
where x and y are bodily measurements, and β and α are constants. Modern
concept of allometry is based on the fact that various organs grow at different
rates relative to the standardized size of an organism (Klingenberg 1996; Gebo
1993). When the shape of an organism conforms to predictions based on
maintaining the same shape over a range of sizes, it is said to be in an isometrical
growth pattern; when the shape changes following changes in size, it is allometric
(Claude 2008).
Although asymmetry has been extensively observed in genus Uca,
quantification and the cause of antisymmetry in this genus - especially Uca
forcipata (Adams and White, 1848) and U. dussumieri (Milne-Edwards, 1852) –
has remained unknown. This present study reports that the frequency of lefthanded or right-handed in cheliped of U. forcipata and U. dussumieri is equal and
the handedness occurs in an antisymmetrical way. An asymmetrical body shape is
caused by the faster growth of one cheliped relative the other.
MATERIALS AND METHOD
Sample
This research was conducted between August 2014 and February 2015.
Adult male fiddler crabs which had a carapace width (CRW) of more than 15mm
2
were taken from an area in the West of Tanjung Jabung, Jambi, Indonesia. Crabs
of this size have already developed asymmetrical chelipeds. They were collected
from two stations with different types of habitat 0o48’44.2”S-103o29’2.8”E: sandy
clay substrate and 0o49’3.1”S-103o28’48.7”E: clay substrate; (appendix 1).
Specimens were collected from 08.00-15.00 WIB (low tide and sunshine). The
sample was identified at the Museum Zoologicum Bogoriense (MZB) in Cibinong.
Sample identification was based on criteria established by Crane (1975).
Identification was taken to species level. The number of samples used in this
research was 153 individuals: comprising two species, in the following quantities:
89 individu of Uca forcipata and 64 individu of U. dussumieri.
Data Analysis
Frequency of either handedness
The frequency of ‘right-handed’ and ‘left-handed’ individuals at each
station was compared using the chi-square test (Agresti 2007).
Allometry analysis
Following Huxley’s morphological law (Huxley 1924), allometry analysis
was carried out, in order to study the covariation of size of major and minor
chelipeds (y) relative to different body sizes (x). When α=1, y grows in an
isometric way relative to x; that is, increases of one unit measurement of x will be
followed by increases of the same amount of y. When α≠1, the rate of growth of y
is longer (allometry positive) or smaller (allometry negative) than that of x.
In this study, the body size was estimated using carapace size. Carapace
width (CRW, the distance between two antero-lateral angles in the carapace) was
the most representative of overall size of the crabs (Martins and Masunari 2013).
In a preliminary allometrical comparison (see statistical analysis below) of the
respective growths of CRW and carapace length (CRL, the distance between front
and intestinal of carapace) (Figure 1), it was shown that CRW grew faster than
CRL (Figure 2). Therefore CRW was used as an estimate of body size, as it varies
in parallel with the hypothesized positive allometry of major cheliped.
Cheliped size was measured in terms of length and width. According to
Crane (1975) cheliped length is the distance from the tip of the pollex to the base
of the connection between carpus and manus: (L) for length of the major cheliped,
and (L1) for length of the minor cheliped. Cheliped width is the distance from the
top of the joint between dactyl and manus, to the depression at the base of the
pollex: (W) for width of the major cheliped, and (W1) for width of the minor
cheliped (Figure 3). All measurements were done three times and the average
values were used in the analysis (Rosenberg 1997; Rosenberg 2002; Hirose et al.
2010).
3
3.5
B
3.0
A
2.0
2.0
2.5
2.5
log(CRL)
log(CRL)
3.0
3.5
Figure 1 Schematic measurement of carapace. CRL (carapace length), CRW
(carapace width).
2.6
2.8
3.0
3.2
log(CRW)
3.4
3.6
3.8
2.6
2.8
3.0
3.2
3.4
3.6
3.8
log(CRW)
Figure 2 Comparison of carapace length (CRL) and carapace width (CRW) (a)
Uca forcipata (b) U. dussumieri. In U. forcipata (α=0.96, H0=1,
p=0.01) and U. dussumieri (α=0.93, H0=1 p=1.6x10-6) indicate CRW
grow faster than CRL.
Figure 3 Schematic measurement of cheliped. (A) cheliped length; (B) cheliped
width.
Statistical analysis
Huxley’s equation can be linearized by using logarithms of the original
measurements
log y = log β + α log x …………………………..(2)
4
This equation can be used to describe allometrical growth patterns in respect
of chelipeds and carapace width. The constancy of α is an important parameter in
the assessment of the static allometry of adult crabs. The regression model II was
chosen to find the regression line (Sokal and Rohlf 1969), because this model
takes into consideration the inherent variability of both the carapace and the
chelipeds. This is in contrast to model I, where one of the variables should be
measured without error. The estimate and confidence intervals for the slope of the
model II regression line were measured using the standardised major axis (SMA)
method (Sokal and Rohlf 1969). The Standardised Major Axis Tests and Routines
(SMATR) software provides tools for the estimation, and inferences about
regression lines relative to hypothetical isometric lines (Warton et al. 2012).
RESULTS AND DISCUSSION
Results
Frequency of either handedness
In adult male genus Uca, one of the cheliped grew faster than the other. The
enlarged cheliped can be found on right or left side of the body. This phenomena
is called antisymmetry (Figure 4). This study shows that the frequency of
handedness in U. forcipata and U. dussumieri was equal, and occurred in a
random position (Table 1).
Figure 4 Antisymmetry in (A) U. forcipata and (B) U. dussumieri
Table 1 Frequency of handedness
No
1
2
3
Species
Station
U. forcipata
I
U. forcipata
II
U. dussumieri
II
Total
Right-handed
36
6
36
78
Left-handed
38
9
28
75
p-value
0.8162
0.4386
0.3173
P≤0.05, Frequency of right-handed and lef-handed is significantly different. H0=50:50
5
Allometry analysis
In this study, the asymmetrical growth pattern of major and minor chelipeds
was compared by reference to carapace size. Comparison of CRL and CRW in
Uca forcipata and in U. dussumieri indicated in faster growth of CRW than CRL
and parallel growth major and minor growth pattern than CRL (Table 2).
Table 2 Growth pattern comparison of CRL and CRW
Species
U. forcipata
U. dussumieri
N
89
64
Slope
0.9601498
0.9302653
P
0.01018878
1.640788e-06
Pattern
Allometry (-)
Allometry (-)
p ≤ 0.05 slope is significantly different from 1 (isometry). H0=1
5
Size comparison of body features in U. forcipata and U. dusumieri showed
asymmetry of body shape based on allometrical analysis. Result of analysis shows
that the major cheliped length (L) of U. dussumieri is longer than U. forcipata.
Differences of growth rate between major cheliped lenght (L) of U. forcipata and
U. dussumieri can be showed based on regression line (Figure 5). The y-intercept
value of regression line can be indicated the differences of growth rates.
Overlapping of upper limit and lower limit between two regression line leads to
parallel growth rates. Meanwhile, non-overlapping of upper limit and lower limit
between two regression line indicates non-parallel growth rates (Table 3).
L
3
L1
W1
1
2
log(TRAITS)
4
W
1
2
3
4
5
log(CRW)
Figure 5 Growth pattern comparison between traits in Uca forcipata (red circle)
and U. dussumieri (black circle); L (major cheliped length),W (major
cheliped width), L1 (minor cheliped length), W1 ( minor cheliped width).
6
Table 3 Elevation regression line value of U. forcipata and U. dussumieri
Traits
L
W
L1
W1
Elevation
-1.897593
-1.659258
-1.073495
-2.0793661
U. forcipata
Lower limit Upper limit
-2.203430 -1.591755
-1.928521 -1.389994
-1.230476 -0.916513
-2.279556 -1.879175
Elevation
-2.838938
-1.552041
-1.080059
-1.893872
U. dussumieri
Lower limit Upper limit
-3.412637 -2.265238
-2.067133 -1.036949
-1.231496 -0.928622
-2.111192 -1.676551
L (major cheliped length),W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width);
The analysis of the two sets of data was carried out. First, data for each
species, irrespective of handedness (Table 4); and second, data separated for righthanded and left-handed (Table 5). When the slope is significantly different from 1,
an allometric growth pattern (p ≤ 0.05) was indicated. The major cheliped shows
positive allometry, and the minor cheliped shows an isometric growth pattern,
with respect to CRW, for both of groups of data (Figures 6 and 7).
Table 4 Allometry analysis of U. forcipata and U. dussumieri
Measurement
Species
L
U. forcipata
U. dussumieri
W
U. forcipata
U. dussumieri
L1
U. forcipata
U. dussumieri
W1
U. forcipata
U. dussumieri
N
89
64
89
64
88
63
88
63
Slope
1.705365
1.973034
1.327799
1.267016
1.025352
1.042195
0.971302
0.898517
Intercept
-1.897593
-2.838938
-1.659258
-1.552041
-1.073495
-1.080059
-2.0793661
-1.893872
P
Pattern
0
Allometry (+)
0
Allometry (+)
2.515765e-13 Allometry (+)
0.0002343904 Allometry (+)
0.3217848
Isometry
0.06348424
Isometry
0.3916357
Isometry
0.9663027
Isometry
L (major cheliped length) ,W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width); p ≤ 0.05 slope is significantly different from 1 (isometry); H0=1.
Table 5 Allometry analysis of handedness U. forcipata and U. dussumieri
Measurement Species
L
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
W
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
L1
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
W1
U. forcipata
U. forcipata
U. dussumieri
U. dussumieri
Handedness
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
n
43
46
36
28
43
46
36
28
43
45
35
28
43
45
35
28
Slope
1.790828
1.604728
2.007487
1.935153
1.348406
1.303960
1.310316
1.216952
1.014016
1.038193
1.059596
1.023603
0.9455919
1.038193
0.8431879
0.9509932
P
0
3.330669e-16
1.498801e-14
5.734546e-11
1.939273e-07
8.41641e-07
0.002898705
0.03531351
0.6566541
0.3581239
0.03803067
0.4698372
0.2862765
0.9974495
0.001756304
0.3438264
Pattern
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Allometry (+)
Isometry
Isometry
Allometry (+)
Isometry
Isometry
Isometry
Allometry (-)
Isometry
L (major cheliped length) ,W (major cheliped width), L1 ( minor cheliped length), W1( minor
cheliped width); p ≤ 0.05 slope is significantly different from 1 (isometry); H0=1.
7
A
B
4
W(+)
3
L1
L(+)
2
L(+)
log(TRAITS)
3
L1(+)
2
log(TRAITS)
4
W(+)
W1(-)
1
1
W1
1
2
3
4
1
2
log(CRW)
3
4
log(CRW)
Figure 6 Growth pattern comparison between traits in (A) right-handed and (B)
left-handed of U. forcipata. L (major cheliped length), W (major
cheliped width), L1 (minor cheliped length), W1 (minor cheliped
width). (+) indicate positive allometry and (-) indicate negative
allometry.
B
A
3
W1
1
W1
L1
2
2
L1
W+
log(TRAITS)
3
W+
1
log(TRAITS)
4
L+
4
L+
1
2
3
4
log(CRW)
1
2
3
4
log(CRW)
Figure 7 Growth pattern comparison between traits in (A) right-handed and (B)
left-handed U. dussumieri. L (major cheliped length), W (major
cheliped width), L1 (minor cheliped length), W1 ( minor cheliped
width). (+) indicate positive allometry and (-) indicate negative
allometry.
Discussion
Frequency of either handedness
In the adult male of genus Uca, one of the chelipeds grew faster than the
other. The enlarged cheliped can be found on the right or left side of the body.
This phenomenon is called antisymmetry. The relative frequency of either
handedness is useful as an indicator of grouping within genus Uca. In most
populations of Uca, the ratio of right-handed to left-handed is 50:50 (Crane 1975;
Backwell et al. 2007; Martins and Masunari 2013). U. forcipata and U.
dussumieri, which were identified as belonging to the Deltuca subgenera, show
8
equal frequency of either handedness (p≤0.05). Jones and George (1982) also
found that U. dussumieri had equal proportions of right-handed and left-handed
males. In contrast, another study in southeast Sulawesi found 14 left-handed and
two right-handed males of U. dussumieri (Weis and Weis 2004). In Thallasuca,
another subgenera of Uca showed a predominance of right-handed males (Jones
and George 1982).
Development of antisymmetrical traits is almost never inherited.
Antisymmetrical development is triggered by the external environment (Vanberg
and Costlow 1966; Yamaguchi 1977; Palmer 2004; Palmer 2012). The major
cheliped in genus Uca develops in parallel with sexual maturation. It develops for
the first time in the seventh juvenile stage of juvenile, although there is no
obvious sign of asymmetry at that stage (Pralon and Negreiros-Fransozo 2007;
Vieira 2010). Sexual maturation is not the only possible factor however; loss of
one cheliped before the immature stage, also determined handedness. It has not
been established whether handedness in Uca is caused by genetic factors, or an
imbalance differentiation during growth because of the loss of one claw (Vanberg
and costlow 1966; Yamaguchi 1977).
The major cheliped is used for combat and the attraction of mates. When
this cheliped is lost, it will grow back on the same side. The respective
handedness in the male Uca could affect fight activity. In one population, the
choice of fighting a rival with the same or different handedness can affect fighting
tactics. Right-handed males are significantly more likely to fight than left-handed
males. When left-handed males do fight, they are less likely to win (Backwell et
al. 2007).
Allometry analysis
Standard growth of body dimensions between individuals in the same
species or different species has biological consequences (Pralon and NegreirosFransozo 2007). In this study, asymmetrical growth patterns of chelipeds were
compared with carapace size. CRW was considered the best predictor, relative to
other body dimensions, and considered an appropriate proxy for body size since it
is most representative of the overall size of crabs (Araujo et al. 2012; Martins and
Masunari 2013).
Major cheliped length in U. dussumieri is longer than in U. forcipata. The
propudus and the dactilus in U. dusssumieri are both slimmer than in U. forcipata.
These factors caused a larger total length of cheliped in U. dussumieri than the
thicker one found in U. forcipata. The relative dimensions of cheliped size can be
caused by genetic factors, but in some cases can be influenced by environmental
factors (Murniati 2010). Based on the major cheliped length (L) of U. dussumieri
longer than U. forcipata, further analysis separated these two species (interspecies
analysis).
The major cheliped grows allomertical positive and the minor cheliped
grows isometry with respect to CRW (appendix 2). Generally within a species, the
major claw growth exhibits positive allometry, while the minor claw grows
isometrically (Rosenberg 2002). The growth pattern in male and female of genus
Uca indicates their sexual functions; disproportionate growth of only one of the
chelipeds in males, and increase of abdomen size in females (Araujo et al. 2012).
An imbalance in the relative sizes of major and minor chelipeds, shows an
9
asymmetrical pattern in U. forcipata and U. dussumieri. Isometry shows a linear
regression of 45o and indicates similar proportions of size growth between
predictor and response. Meanwhile, allometry leads to a linear regression with an
angel ≠ 45o; more than 45o for positive allometry, and less than 45o for negative
allometry.
CONCLUSION
The frequencies of handedness in U. forcipata and U. dussumieri were equal
for right-handed and left-handed. The occurrence of major chelipeds on either side
in U. forcipata and U. dussumieri shows an antisymmetrical growth pattern.
Major chelipeds showed positive allometry and minor chelipeds showed isometry
for both species. This might have caused the growth imbalance between chelipeds
that leads to the asymmetry of body shape.
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12
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APPENDIXES
Appendix 1 Location of research sampling
12
13
Appendix 2 Linear regression equation between body features (CRW is predictor) in Uca forcipata and U. dussumieri
Relation between
L vs CRW
W vs CRW
L1 vs CRW
W1 vs CRW
Species
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
U. forcipata
U. dussumieri
y = ax+b
L = 1.705365 CRW - 1.897593
L = 1.973034 CRW - 2.838938
W = 1.327799 CRW - 1.659258
W = 1.267016 CRW - 1.552041
L1 = 1.025352 CRW - 1.073495
L1 = 1.042195 CRW - 1.080059
W1 = 0.971302 CRW - 1.080059
W1 = 0.898517 CRW - 1.080059
p ≤ 0.05
p ≤ 0.05
p ≤ 0.05
p ≤ 0.05
p ≥0.05
p ≥0.05
p ≥0.05
p ≥0.05
Slopes
(Allometry)
(Allometry)
(Allometry)
(Allometry)
(Isometry)
(Isometry)
(Isometry)
(Isometry)
Intercepts
Non-parallel
Parallel
Parallel
Parallel
14
CURRICULUM VITAE
Author was born in Jambi on December 22nd, 1990. Author is the third
child of five from the parents, Aminursan and Lily Handayani. In 2008 author
studied in Jambi University, Faculty of Education and Teacher Training, in major
of Biology education and graduated from Jambi University in 2012. In 2013
author got BPPDN scholarship from DIKTI and enrolled in the Graduate School,
Major of Animal Biosciences, Bogor Agricultural University.