Prepared by;SOBDIHAFARAHPREZYOOB

BASIC INFORMATIONS

Authors’ name: Han Kwai Hin, Robert B. Stuebing and Harold K. Voris.

Article’s title : Population Structure & Reproduction In The Marine Snake, Lapemis hardwickii Gray, From The West Coast Of Sabah.

Journal’s title :The Sarawak Museum Journal (1991) .

ABSTRACT &INTRODUCTION

ABSTRACT – SUMMARY

The study was done in west coast of Sabah

January to December 1987

No sexual dimorphism

There is a maximal amount of energy to be invested into reproduction

CRITIQUE

The parabolic relationship between egg weight and body weight of the females suggests that there is a maximal amount of energy to be invested into reproduction.

Instead of suggest, they can use more convincing word such as shows/indicate.

No keywords stated

INTRODUCTION – SUMMARY

Little is known about the sea snakes in Borneo

Only Laticauda colubrina has been studied in Kalampunian Damit

10 species known from Sabah

Purpose of this study – examine population structure and variations in reproductive conditions of Lapemis hardwickii

SUGGESTIONS

Can put the general information about the population structure and reproduction of sea snakes

To provide basic information about sea snakes to readers

METHODOLOGY

754 specimens of Lapemis hardwickii

Depth 25­30 m

Frozen in ice

Rethawed (soaking in water)

Total length and tail length (mm)

Total length ­tail length  = snout­vent length

Recorded the individual mass (gram)

Sexing the snake (absence or presence of hemipenes)

         Male ­ squeeze 

posterior to anus

  Female ­ pair of 

genital openings

Examine reproductive structures

Male­Measure lefttestes (mm)­Stores in 10%formalin­Processed withTisumation (Fishermodel) ­Selected 35specimens forhistological analysis

Female­Count yolky eggs (inoviducts)­Eggsfound withembryos (separatelyregarded anddetermine themass)­determine totallength, tail length andsnout­vent length ofembryos­Isolated and weighedthe wet fat

DATA ANALYSIS

Student’s t-tests (examine snout-vent length, tail length and weight differences between the sexes)

Regression (determine correlation)

      Male  – testis length 

and snout­vent length

Female – egg weight and body 

weight of the egg­bearing 

­mean yolk weight, and mean embryo of a clutch, 

­mean total length of embryos and mean embryo weight of a clutch

CRITIQUE

  

Slightly confusing, did not mentioned male or female snakes.

RESULT

RESULTS

Sample collected 363 males 391 females  N= 754

MORPHOMETRIC VARIATION (RANGE)

Total length = 364 – 972 mmSnout­vent length = 323 ­ 880 mmTail length = 41 – 105 mmBody weight = 263.63.6 g

Females were significantly heavier and longer in snout-vent length than males.o Females (277.0±5.2 g, 653.6±3.8 mm)o Males (249.2±5.0 g, 640.1±4.0 mm)

However, total length were not significantly different between two gendero Females (727.3±4.3 mm)o Males (716.0±0.4 mm)

Mean tail length was significantly greater in males (76.6±0.5) than females (74.1±0.5)

REPRODUCTIVE CONDITION

Ratio of adult male to female = 0.93

Ration of male/female embryos = 1.37

94.4%, female specimens caught found carrying large egg yolks from January to March.

47.5% of them have three eggs (clutch size varied from 1­6 eggs)

Proportion of gravid females was high during january(80%), February(92.3%) and March(95.1%) and dropped drastically form July(18.2) to October(2.6%).

Frequency of twins = 2/64

Frequency of triplets= 1/64)

Comparison (Voris and Jayne method, 1979) of snout­vent length for clutches and clutch size suggest that:o Growth rate = 95mm in 90 days, 1mm a day.

Estimation of baby snakeso birth weight = 39.7 go Total length = 373.4 mm

From Figure 9, there are gradual increase in wet fat deposition in female throughout September to November and decrease in December.

CRITIQUE

Results relevant to objectives.

The morphometric variation data is to examine the population structure.

Reproductive condition was also examined in the result.

Overall result can be used.

Confusions during reading

page 465, line 8 to 9.

“Table 1 shows the fluctuations of monthly sample size in

which the number of snakes caught from January to September was three times as numerous as that from January to March.”

Writers idea could not easily reach readers.

Numerical mistake?

Page 465, line 31 (263.63.6) g

DISCUSSIONS &CONCLUSION

What do the observations mean?

•Morphological differences between the sexes are not directly observable in Lapemis hardwickii. Supported by:oFig. 1, 2, and 3oMales have smaller body size, anhances in locating their mates for reproduction (Spellerberg, 1982).

THE STRENGTHo Each graph has a reliable interpretation of data from the

result part.o The interpretation of data seem to be supported by other

research and cited in the study.

1. Reproductive condition. Supported by;

o Fig. 5-10.o Found that 94.9% of female specimens caught from January to

March carried large yolky eggs showing the possibility of synchronized mating patterns in female. This result met with Voris and Lemen (1981).

o The finding that male began producing sperm cells actively at a snout-vent length of 486mm agrees with Bergman’s data (1949).

3. Comparison with other species.They are;o Laticauda colubrina.o Pelamis platurus.o Enhydrina schistosa.

THE WEAKNESS

2. Undefined value - the value stated here has no relevance origin.

1. References with no date/year.

3. Authors with no date/year reference.

4.  Legends of the graph is incomplete.

1. “..the estimated total length at birth obtained in this study differs greatly from Bergman’s estimation..”

“Whether such differences in estimation were due to interpopulation differences or methods used are not known.”

(pp. 473)

o The authors have no solution/idea on the problem raised.

o But from the methodology part, there was stated that; “Specimens with tails partially severed were excluded

from calculations of tail length and snout-vent length.” (pp. 464)

o Besides, number of the excluded snakes is not stated.

OUR REFERENCES:

4)Kuyper, B.J. (1991). Bringing up scientists in the art of critiquing research.

Bioscience 41(4), 248-250.

9) Wood, J.M. (2003).Research Lab Guide. MICR*3260 Microbial

Adaptation and Development Web Site. Retrieved 30 September

2009, from

http://www.uoguelph.ca/mcb/courses/MICR3260/research_lab/index.

htm