Life-History Variation in a Community of Lacertid Lizards from the Lake Skadar Region (Montenegro) D
Total Page:16
File Type:pdf, Size:1020Kb
HERPETOLOGICALJOURNAL, Vol. 6, pp. 125-132(1996) LIFE-HISTORY VARIATION IN A COMMUNITY OF LACERTID LIZARDS FROM THE LAKE SKADAR REGION (MONTENEGRO) D. BEJAKOVICI*,I. ALEKSIC',A. TARASJEV1**,J. CnNOEnNJA-ISAILOVIC'. G. DZUKIC', M. L. KALEZIC2 t Institutefor Biological Research "sinisa Stankovic", 29 Novembra 142, 11000 Beograd, Yugoslavia 2lnstitute of Zoology, Faculty of Biolog, Studentski trg 3, 11000 Beograd, Yugoslavia * Present address: MAF Quality Management,Plant Protection Centre, PO Box 24, Lincoln, New Zealand a* Author for corresPondence We compared life-history attributes of Algyroides nigropunctatus, Lacerta oxycephala, Podarcis melisellensis andPodarcis muralis populations in the Lake Skadarregion (mainland and islands). These lacertids are moderately sized with differing morphology (flattened vs. cylindrical). They have similar duration ofegg incubation, size at onsetofsexual maturity, size of hatchlings, and rate of juvenile growth. Clutch size is variable between populations and species:P. muralis producedlarger clutchesthan the other species,especially ,4. nigropunctatus andL. oxycephala.A significant differencein egg sizewas apparentat the population level only. Smaller clutch size and elongatedeggs were associatedwith a flattened body in L. oxycephala. A canonicaldiscriminant analysis ofreproductive variables showed that speciessimilarities in ecologicalcharacteristics reflect phylogenetic relationships. INTRODUCTION lacertidlizard community of the Lake Skadarregion (CrnobrnjaJsailovic& Dzukic, 1995). In thisreport we Componentsof an organism'slife history (reproduc- comparethe life-historyattributes of four sympatric(in tive characteristics,behaviour, longevity, growth rate, somecases syntopic) species, both in a coastalarea and etc.) may be viewed as co-adaptedtraits that in concert on islandsin LakeSkadar. In additionto differencesin produce the best strategy for survival in a particular en- the geneticbackground and meaningof the species, vironment (e.g. Stearns, 1976). Most studies on theselacertids also differ in morphology, life-historiesof lizards show large interspecificdiffer- distribution andecological traits. ences and considerable intraspecific temporal and geographic variations of the traits (reviewed in Dunham et al., 1988). Thesevariations have been at- MATERIALSAND METHODS tributedprimarily to the local environment(e.g. Tinkle SPECIESSTUDIED and Dunham, 1986;Abts, 1987).However, foraging mode, phylogenetic inertia and morphological con- The speciesstudied here represent the closestgenera straints (body size and shape) were also evoked as within Old-World lacertids,with affinities as follows: factorspotentially influencing variation of life-history (P odarc is-Lac erta) (Al gr oides) (Arnold, I 989). The traits (e.g.Vitt & Congdon,1978; Vitt, 1981;Vitt & Dalmatian Algtroides, Algtroides nigropunctatus, Price, 1982).In order to obtain empiricaldata essential ranges along the coastal region of the Adriatic and Io- to discernthe relative importanceof all thesedetermi- nian seas,from Italian and Sloveniankarst regionsto nants for the evolution of life-history traits in lizards, the Akarnanien region (Greece), including some north- simultaneousstudies on a setof syntopicpopulations of ern Adriatic islands. There are a few significant range speciesdiffering in the degree of their phylogenetic penetrationsinland. This speciesis usually encountered relatedness,ecological traits and morphology, are ap- in degradedscrub, bushes between fields and rocky parently needed(Vitt, 1986;Tinkle & Dunham, 1986; cliffareas, usually nearwater. The sharp-snoutedrock Henle, 1990).Studies on life-history traits of lacertids lizard,,Lacerta oxycephala, is a steno-endemicBalkan (Lacertidae)in comparisonwith other lizard families species,restricted in its range to a narrow zone along are still scarce(see Dunham et al., 1988).This is par- the Adriatic coast,from the river Krka to the northwest- ticularly true for the Balkan'lacertids(Podarcis spp., ern part of Albania. L. orycephala differs distinctly in Lacerta spp.,Algtroides spp.,Ophisops spp.). Also, al- morphology from all other lacertidsby having a flat- most all previousstudies of theselizard populations tenedbody, with a very pointedsnout. In an ecological havebeen conducted in locationslacking diverselizard sense,this speciesis peculiar among the Balkan's communities.Out of 19 speciesthat canbe encountered lacertidsbecause it is the most specialistpetricole, in- throughout the Balkans, nine speciescompose the habiting mostly sunny cliff faces,rock-pavements, 126 D. BEJAKOVICET AL. stone piles and screes. The Dalmatian wall lizard, sides of railroad tracks and nearby road (Podgorica- Podarcis melisellensis,is a polymorphic species,with a Bar). P. melisellensis shares this habitat with p. considerableabundance in diverse habitats, but it is muralis. Malo Starcevois a small island (0.9 ha) with mainly encountered in densely vegetated places. It densepopulations of P. muralis only. Beska Velja is ranges from Monfalcone (Italy) to Skadar (Albania) one of the biggestislands (15.9 ha), with Z. orycephala along the coastalzone of the Dinaric Alps, extending as the only lizard species.The island Malo Besko (1.7 inland in Lika, Hercegovina,Montenegro and Albania ha) is characterizedby a dense tree vegetation and (Tiedemann& Henle, 1986).The common wall lizard, grassypatches with bouldersof varioussizes, inhabited Podarcis muralis, has a wide geographicdistribution by a relatively robustpopulation of P. melisellensis.ln (central and southern Europe), with immense geo- nearby waters, mainly on rocks, many P. muralis indi- graphic variation in morphology and habitat viduals can be encountered.Mali Moracnik is a characteristics(Gruschwitz & Bohme, 1986).Thus, moderate-sizeisland (0.7 ha), with a sparsetree vegeta- this lizard is thought to be more opportunisticwith re- tion and grassyfields among large stony patches.Here gard to microhabitatpreference than its relatives. the largeP, melisellensripopulation inhabits grassy ar- eassyntopically with L. orycephala.A few individuals of P. muraliswere noticedon this islandas well. Bisage is an island of 2.8 ha, with P. melisellensisand A. HABITAT AND SPECIES COMPOSITION nigropunctatls as the lizard inhabitants. Lake Skadaris the largestof the Balkan lakes.The lake is locatedin a karst terrain in the outer part ofthe DATA COLLECTION AND STATISTICAL ANALYSES south-easternDinaric Alps. Mountains rise steeply from the lake'ssouth-western shore along which an ar- Details about field and laboratorymethods (body chipelagoof about forty large and small islandsexists. and egg measurements,egg-laying process, egg incu- Vegetationof this part, including the islands,is charac- bation period, hatchlingsraised), including data on terizedby maquisand guarigue.Scattered xeromorphic clutch and egg size,size at sexualmaturity for females treesare separatedby patchesof dry grassand herbs. of L. oxycephala, P, melisellensis and P. murahs, can Larger islandsusually have a water's-edgerocky zone be found in our previouspapers on reproductivechar- with scatteredtrees only, and a cenffalgrassy zone with acteristicsofthe lacertidsfrom the Lake Skadarregion bushy vegetation. The northern and north-eastern (Aleksic& Tucic, 1994;Bejakovic et al.,1995,1996). shores are flat, providing an extensive semi-littoral Snout-ventlength (SVL) was taken as a measureof zone.This formerly inundatedterrain with recentallu- overall size. Head dimensions(length, height, width), vial depositsis now mostly under cultivatedsoil, with relative to SVL, expressedthe body shape.The length fragmentsof common oak forests.The climate of the of hind limb relativeto SVL was consideredas a mor- region is characterizedby a large amountof precipita- phologicalindicator of mobility capacitiesof the lizard tion andhigh summertemperatures (Lasca et al.,1981). species(see Pianka, 1986). Egg volume(V) wastaken The shoreregion of the lake hastwo distinctzones with asthe overall measureof sizeof eggslaid. RCM values respectto lizard distribution, but on the islandsthere were calculatedas the ratio of clutchmass to body mass are speciesin various combinationsof allotopic and after egg laying (see Shine, 1980) and were used as a syntopicoccurrence (Crnobrnja-Isailovic & Dzukic, measureof reproductiveinvestment per clutch. The 1995). P. muralis and L. orycephala appearto be the sizeof the smallestfemale with enlargedvitellogenic most common species,probably due to their better follicles was consideredthe minimum size at maturity. colonizing abilities. They are the only specieswith Femalereproductive characteristics were studiedon allotopicaldistributions. L. oxycephalaoccurs as the a number of individuals,except for A. nigropunctatus only lizard on 19, and P. muralis on 10,of the 40 is- whereonly ten sexuallymatured females were avail- lands.These islands are the most denselypopulated (up able, of which three laid eggs. Nevertheless,we to one individualper 2 m2,unpublished data.). When includedthis speciesin this study, though we were speciesare syntopic, spatial partitioning occurs; in such awarethat the paucity of samplesize precludedwell- casesthey generally follow their preferedhabitats. supportedconclusions. Thus, P. melisellensisis mostly encounteredin veg- Statisticswere calculatedwith SAS package(SAS etated areas, P. muralis and L. oxycephala incline to Institute,1989). Mean valuesand standarderrors of shorelinerocky zones,while l, nigropunctatasshow life-history traits were weighted