Cox, Robert L., Jr.

Trauth, Stanley E.

Wilhide, J. D.

Worley, Hilary J.

English

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 49 Article 42 1995 Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander, Ambystoma talpoideum (Caudata:Ambystomatidae), from Northeastern Arkansas and Clutch Comparisons with Other Ambystoma Species Stanley E. Trauth Arkansas State University Robert L. Cox Jr. Arkansas State University J. D. Wilhide Arkansas State University Hilary J. Worley Arkansas State University Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Animal Studies Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Trauth, Stanley E.; Cox, Robert L. Jr.; Wilhide, J. D.; and Worley, Hilary J. (1995) "Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander, Ambystoma talpoideum (Caudata:Ambystomatidae), from Northeastern Arkansas and Clutch Comparisons with Other Ambystoma Species," Journal of the Arkansas Academy of Science: Vol. 49, Article 42. Available at: https://scholarworks.uark.edu/jaas/vol49/iss1/42 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, uarepos@uark.edu. 193Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander,Ambystoma talpoideum (Caudata: Ambystomatidae), from NortheasternArkansas and Clutch Comparisons withOther Ambystoma SpeciesStanley E. Trauth, Robert L.Cox,Jr.1,J.D. Wilhide and HilaryJ. WorleyDepartment of Biological SciencesArkansas State UniversityState University, AR 72467-0599IntroductionAquatic eggs and/or egg masses of many salamanderspecies normally increase in mass by acquiring a consider-able amount of water via osmosis immediately followingoviposition (see Duellman and Trueb, 1986). Most of thiswater gain is restricted to an area between the vitellinemembrane which immediately surrounds the ovum andthe outer egg capsule. Within this region there can be asmany as eight concentric capsular rings per egg (Salthe,1963); as these capsules expand, a gelatinous appearanceis bestowed upon the single egg and/or egg masses. Notonly do egg capsules serve to protect the developingembryo from predation and physical harm, but they alsoare vital to successful fertilization of the egg and must bepresent for hatching to occur (Duellman and Trueb,1986).There are six species of ambystomatid salamandersthat occur in Arkansas (Conant and Collins, 1991); ofthese, five species {Ambystoma annulatum. A. maculatum,A. talpoideum, A. texanum, and A. tigrinum) normally laytheir eggs by attaching them to submergent vegetation inthe form of masses or clusters, whereas the other species(A. opacum) deposits its eggs in a terrestrial nest at theedge of a pond or pool of water. Among the formerspecies, only the mole salamander (A. talpoideum) hasbeen shown to vary geographically by exhibiting two egg-laying patterns (see review inSemlitsch and Walls, 1990).Within the Mississippi River Valley ecoregion this speciesdeposits eggs in the form of egg clusters (Shoop, 1960;Raymond and Hardy, 1990), whereas in the AtlanticCoastal Plain single eggs are attached to vegetation(Semlitsch and Walls, 1990). In addition, this species ispolymorphic (exhibition paedomorphic and metamor-phic forms) in Arkansas (Trauth et al., 1993) as well as inother parts of its range (see Scott, 1993).The present study documents egg mass and clutchcharacteristics of terrestrial morphs of A. talpoideum inArkansas. Inaddition, we compare similar egg mass traitsof this species with another ambystomatid species, thespotted salamander (A. maculatum). Lastly, we summarizeegg mass and/or clutch size of Ambystoma species inArkansas.i(RLC-deceased)Materials and MethodsEgg masses of the terrestrial morph of the mole sala-mander, Ambystoma talpoideum, were collected from twotemporary ponds in Greene County, Arkansas, inDecember of 1988 and 1994. These seasonal, temporaryponds (abandoned gravel pits) differed markedly fromthose permanent ponds that typically contain paedomor-phic individuals. Egg clusters (with embryos mostly inearly stages of development) were taken to the laboratoryand placed into fixative (10% formalin) within 24 hr aftercollection. Allegg masses are housed in the ArkansasState University herpetological collection.Laboratory procedures included the recording ofmass (g) and number of eggs per egg mass. While mea-suring egg masses, individual masses were removed fromfixative and blotted dry; mass was recorded with a triple-beam balance (to the nearest 0.1 g). Egg masses of thespotted salamander (mostly collected on 8 March 1988from permanent ponds in Independence, Izard andMarion counties) were processed in a similar manner. (Inorder to support the contention that preserved egg mass-es actually gain mass following preservation nine eggmasses of A. maculatum, collected on 28 January 1995,were weighed (massed) prior to preservation and thenone month thereafter. In all cases, these egg massesgained at least 100% in total mass.) Mean values inTable1are accompanied by + two standard errors.Results and DiscussionThe morphology of egg masses of metamorphic A.talpoideum is shown inFig. 1. The globular nature of theseegg masses supports the dichotomous pattern of eggmass structure for this species as discussed by Semlitschand Walls (1990). The masses differed structurally fromthose of A. maculatum (illustrated by Gilbert, 1942) main-lyby being more fragile. For example, upon collection inthe wild,egg masses of A. maculatum are typically charac-terized by their turgidity or an ability to withstand manip-ulation. Egg masses ofA. talpoideum also retain a globularappearance as viewed in recently-oviposited massesProceedings Arkansas Academy ofScience, Vol.49, 1995193Journal of the Arkansas Academy of Science, Vol. 49 [1995], Art. 42Published by Arkansas Academy of Science, 1995Fig. 1. Egg masses of the terrestrial morph of Ambystoma talpoideum collected inGreene County, Arkansas. A.Recently-oviposited egg mass (shown attached to a twig) with around 32 eggs. B.Egg mass with around 55 embryos nearing hatch-ing.(developmental stage determined by embryonic stage) aswell as in older masses whose embryos are nearing hatch-ing (Fig. 1Aand B,respectively). The gelatinous capsulesof each egg mass eventually break down or weaken inboth species as embryos near hatching (Fig. IB).Thenature of the egg mass of terrestrial morphs of thisspecies also differs sharply from those of the paedo-morphs (observed inArkansas) whose eggs are laid singly(sometimes attached to one another) and are very fragile(S.E. Trauth, unpubl.).Table 1. Data on the number of eggs per egg mass (orclutch size) for Ambystoma species documented inArkansas.Species N Average Egg Mass Range SourceSize (+ 2 SE)A.annulatum-14.0 4-31 Trapp, 19567.8 2-17 Trapp, 19561-50+ SpotilaandBeumer, 1970A.maculatum 75 148.7 20-334 This study(± H.9)A.opacum 10 107.1 87-124 Trauth etal.,1989bA. talpoideum 60 41.1 12-99 This study(±5.0)A. texanum 34 12.6 5-22 Trauth et al.,(+ 1.5) 1990A. t. tigrinum 2 130.5 96-165 Trauth et al.,1990Figure 2 illustrates a comparison of mass gain in eggmasses (following preservation) of A. talpoideum and A.maculatum. Although data shown in Fig. 2 are not intend-ed to actually represent a measure of mass gain of eggmasses in the wild (nor do data in Fig. 2 signify orexpress any inherent osmotic quality of these egg clus-ters), the degree of intraspecific variation associated withegg mass size and maximum mass gain is intriguing. Ifweassume that osmosis is not encumbered or halted afterpreservation (see above), then each egg mass of equal eggnumber and size should presumably undergo a similarmass gain. A comparison of the two December collec-tions (collected six years apart) for A. talpoideum (Fig. 2)revealed differing mass gains per egg mass of equal eggnumber. This was also observed for egg masses of A. mac-ulatum. These differences suggest individual variation inovipositing females and that this variation presumably isgrounded either in the selective pressure on femalesovipositing in temporary ponds vs. permanent ponds orin the inherent variability of reproductive and/or life-his-tory characteristics associated with ovipositing females inany given population [as has been observed in manyambystomatid salamanders (e.g., see Walls and Altig,1986)]. For instance, differences inmass inegg masses ofsimilar size could be the result of the following types ofvariation: 1) variation inovum size at ovulation within afemale orbetween adult females of varying body sizes, 2)variation in egg size (with egg capsules) at ovipositionProceedings Arkansas Academy of Science, Vol.49, 1995194Journal of the Arkansas Academy of Science, Vol. 49 [1995], Art. 42https://scholarworks.uark.edu/jaas/vol49/iss1/42Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander, Ambystoma talpoideum(Caudata: Ambystomatidae), fromNortheastern Arkansas and Clutch Comparisons with Other Ambystoma Specieswithin a female or between adult females of varying bodysizes, 3) variation in the number of eggs oviposited peregg mass within a female or between adult females ofvarying body sizes, and 4) variation associated with theaquatic habitat (e.g., temporary vs. permanent ponds). Itis uncertain whether variation in developmental stage atthe time of collection has any influence on how the fixa-tive affects the egg capsules; furthermore, the overalleffects of formalin inaltering osmotic phenomena insideegg capsules remains uncertain (but see Vittet al., 1985).Previous studies have documented variation in ovumsize and number in Ambystoma. Shoop (1960) found thatadult metamorphic female A. talpoideum ranging from 57to 66 mm in snout-vent length (n =14) contained from 226to 401 vitellogenic ova. Walls and Altig(op. cit.) foundova diameters ranging from around 1.76 to 1.93 mm inA.talpoideum and from 2.2 to around 2.7 mm inA. macula-tum. Semlitsch (1987) reported that adult paedomorphicA. talpoideum vary greatly in the number of ova producedper clutch and that this parameter was directly related tofemale body size. Furthermore, whether a pond is tempo-rary or permanent has been shown to affect the size aswell as number of eggs per clutch in A. maculatum(Woodward, 1982). Woodward (op. cit.) found that largerfemales inpermanent ponds produced larger eggs but donot increase the number of eggs per clutch and that per-manent pond females produced more eggs per clutchthan do temporary ponds females. Partitioning of clutch-es could, therefore, result inboth large and small femalesovipositing similarily-sized egg masses; however, each eggmass could conceivably gain a different amount of water,because of egg size differences.Fig. 2. Number of eggs per egg mass as a function ofmass (g) per egg mass of preserved egg masses inAmbystoma talpoideum and A. maculatum .Clusters ofrecently-oviposited eggs (as shown by arrows) were notpreserved prior to mass determination. Small solid circles=egg masses collected on 19 December 1988; intermedi-ate-sized, solid circles = egg masses collected 19December 1994.geographic areas of sympatry can often be difficult,espe-cially when several species are ovipositing in the samepond or ditch at the same time. Yet, there are species-spe-cific differences in the annual timing of oviposition aswellas preferred egg-laying habitats that can usually assistin assigning egg clusters to a species of Ambystoma. Noreliable established suite of egg mass characteristics caneasily separate species insome situations. InArkansas, wesuggest that egg masses with eggs numbering over 100per mass (and oviposited in ponds) be considered to bethose of either A. maculatum or A. tigrinum. Winter breed-ing of A. annulatum (not exclusively during the fallmonths; see Trauth et al., 1989a) combined with theirsimilar egg mass size withA. talpoideum and A. maculatumcan make distinguishing egg masses ranging from 25 to100 eggs problematic. In this case, egg masses of A. macu-latum can be separated from the other two based on thegreater turgidity of the mass (inA. maculatum vs. A.annu-latum) along with the possibility of the presence of agreen algae inA. maculatum (Gilbert, 1942); separation ofA. talpoideum from the other two would be based upongreater fragility of egg masses. In egg masses fewer thanOur data inFig. 2 also suggests that maximum massvalues for egg masses exhibited by both salamanderspecies are consistent with differences in egg size. Forexample, in A. talpoideum an egg mass of 14 eggs had amaximum mass of 44.6 g, whereas an egg mass of 75 eggshad a maximum mass of 192.6 g. Therefore, the averagemass per egg for the former is 3.2 g, and the averagemass per egg for the latter is 2.6 g. On the other hand, inA. maculatum an egg mass of 120 eggs had a maximummass of 214.4 g, whereas an egg mass size of 299 eggs hada maximum mass of 331.6 g.Therefore, the average massper egg for the former is 1.8 g, and the average mass forthe latter is 1.1 g. These ranges suggest that the ability tojain mass is more pronounced in the smaller, more frag-le egg capsules of A. talpoideum than in the larger eggswith firmer egg capsules of A.maculatum.A summary of egg mass size (or clutch size as inA.opacum) for Ambystoma species collected inArkansas isshown in Table 1. Because five of the six species ofAmbystoma are aquatic egg-layers and because interspecificoverlap inegg mass size occurs among several species, thefield identification of a particular species' egg mass inProceedings Arkansas Academy of Science, Vol.49, 1995195Journal of the Arkansas Academy of Science, Vol. 49 [1995], Art. 42Published by Arkansas Academy of Science, 1995?25, as seen inA. talpoideum and A. texanum, a reliance onegg-laying habitat may be the best guide. Ditches and/orsmall temporary pools are commonly utilized by A. tex-anum, whereas A. talpoideum generally prefers ponds.Insummary, data on egg mass characteristics of theterrestrial morph of the mole salamander, Ambystomatalpoideum, were examined and compared to those of thespotted salamander {Ambystoma maculatum) collected else-where in Arkansas. We also provide a summary of eggmass traits for other Ambystoma species inhabitingArkansas. Although the egg masses of A. talpoideum (ter-restrial morph) are oviposited in fragile clusters, they canwithstand collection, manipulation, and preservationwhile retaining their globular-like, structural morphology.Bycomparison, eggs laidby paedomorphs of this speciesare normally not found in clusters and are extremely sus-ceptible to damage or loss of integrity upon handling.Average clutch size in A. talpoideum was 41.1 eggs (14-99;n = 60), whereas A. maculatum averaged 148.7 (20-334; n =75). Mass (g) changes while in preservative in A.talpoideum and A. maculatum indicated that eggs of bothspecies gained mass. The reliability of using preserved(museum) egg masses to provide information on selectedreproductive characteristics insalamanders remains spec-ulative and awaits further scrutiny.Literature CitedConant, R. and J.T. Collins. 1991. Afield guide toreptiles and amphibians ofeastern and central NorthAmerica. 3rd edition. Houghton MifflinCo., Boston,Massachusetts, 450 pp.Duellman, W.E. and L.Trub. 1986. Biology of amphib-ians. McGraw-Hill,New York, 670 pp.Gilbert,P.W. 1942. Observations on the eggs ofAmbystoma maculatum with special reference to thegreen algae found within the egg envelopes. Ecology23:215-227.Harris, R.N. 1980. The consequences of within-year tim-ingof breeding inAmbystoma maculatum. Copeia1980:719-722.Raymond, L.R. and L.M.Hardy. 1990. Demography of apopulation of Ambystoma talpoideum (Caudata:Ambystomatidae) innorthwestern Louisiana.Herpetologica 46:371-382.Salthe, S.N. 1963. The egg capsules in the Amphibia. J.Morph. 113:161-171.Scott, D.E. 1993. Timing of reproduction of paedomor-phic and metamorphic Ambystoma talpoideum. Amer.Midi.Nat. 129:397-402.Semlitsch, R.D. 1987. Density-dependent growth andfecundity in the paedomorphic salamanderAmbystoma talpoideum. Ecology 68:1003-1008.Semlitsch, R.D.and S.C. Walls. 1990. Geographic varia-tion in the egg-laying strategy of the mole salaman-der, Ambystoma talpoideum. Herpetol. Rev. 21:14-15.Shoop, C.R. 1960. The breeding habits of the mole sala-mander, Ambystoma talpoideum (Holbrook), in southeastern Louisiana. Tulane Stud. Zool. 8:65-82.Spotila, J.R. and R.J. Beumer. 1970. The breeding habitsof the ringed salamander, Ambystoma annulatum(Cope), innorthwestern Arkansas. Amer. Midi.Nat.84:77-89.Trapp, M.M.1956. Range and natural history of theringed salamander, Ambystoma annulatum Cope(Ambystomatidae). Southwest. Nat. 1:78-82.Trauth, S.E., M.E. Cartwright and W.E. Meshaka. 1989a.Winter breeding in the ringed salamander, Ambystomaannulatum (Caudata: Ambystomatidae), fromArkansas. Southwest. Nat. 34:145-146.Trauth, S.E., W.E. Meshaka and B.P. Butterfield. 1989b.Reproduction and larval development in the marbledsalamander, Ambystoma opacum (Caudata:Ambystomatidae), from Arkansas. Proc. ArkansasAcad. Sci. 43:109-111.Trauth, S.E., B.G. Cochran, D.A.Saugey, W.R.Poseyand W.A. Stone. 1993. Distribution of the mole sala-mander, Ambystoma talpoideum (Urodela:Ambystomatidae), inArkansas with notes onpaedo-morphic populations. Proc. Arkansas Acad. Sci.47:154-156.Trauth, S.E., R.L. Cox,B.P. Butterfield, D.A. Saugeyand W.E. Meshaka. 1990. Reproductive phenophasesand clutch characteristics ofselected Arkansasamphibians. Proc. Arkansas Acad. Sci. 44:107-113.Vitt,L.J.,J.M. Howland and A.E. Dunham. 1985. Theeffect of formalin fixation on weight of lizard eggs. J.Herpetol. 19:298-299.Walls, S.C. and R.Altig.1986. Female reproductive biol-ogy and larval lifehistory of Ambystoma salamanders:a comparison of egg size, hatchling size, and larvalgrowth. Herpetologica 42:334-345.Woodward, R.D. 1982. Local intraspecific variation inclutch parameters in the spotted salamander{Ambystoma maculatum). Copeia 1982:157-160.Proceedings Arkansas Academy of Science, Vol.49, 1995196196Journal of the Arkansas Academy of Science, Vol. 49 [1995], Art. 42https://scholarworks.uark.edu/jaas/vol49/iss1/42

Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander, Ambystoma talpoideum (Caudata:Ambystomatidae), from Northeastern Arkansas and Clutch Comparisons with Other Ambystoma Species

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Egg Mass Characteristics of Terrestrial Morphs of the Mole Salamander, Ambystoma talpoideum (Caudata:Ambystomatidae), from Northeastern Arkansas and Clutch Comparisons with Other Ambystoma Species

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