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Geographic variation and taxonomy of crested newts (Triturus cristatus superspecies): Morphological and mitochondrial DNA data
Abstract
Within the newt genus Triturus, the large-bodied species in the T. cristatus (crested newt) superspecies show an unusual degree of variation in relative trunk length as a result of among-taxon variation in interlimb vertebral count. Here we examine the systematic value of this feature as assessed by both exterior measurement (Wolterstorff Index) and direct radiographic count of rib-bearing vertebrae, with particular reference to a number of confounding factors (sex differences, hybridisation, geographic variation, allometry, preservation effects). Using our mtDNA haplotype data, which are largely concordant with geographic distribution of species, we find that direct count of the rib- bearing vertebrae performs more reliably (14% misclassification) than external measurement (31% misclassification) as a species identifier. We therefore recommend this feature as a taxonomic tool, although (like external measurement) it breaks down near hybrid zones. To account for the observed biogeographical pattern and phenotype - genotype discrepancies, a scenario is presented that combines the movement of the contact zone between taxa with asymmetric hybridisation. This scenario applies to species interactions in eastern Yugoslavia and western France.
... Triturus dobrogicus is distributed from the Danube River basin floodplains in central Europe to the delta of the Dnipro River in the East (Wielstra et al. 2014). The species spends more time in the water than its congeners and has the longest aquatic phase (Arntzen & Wallis 1999). Bulgaria is at the southernmost part of its range and the species has only been established up to a few kilometers from the Danube (Naumov & Biserkov 2013, Popgeorgiev et al. 2019 and as an unconfirmed exception in the northern Black Sea coast (Gherghel & Iftime 2009). ...
... The species occurs across most of the territory of Bulgaria, from the sea level up to ca. 1700 m elevation; however, it is largely absent from the immediate riverine area of the Danube, as well as from the north-western part of the country (Stojanov et al. 2011). It is the largest, most robust of the Triturus species in Bulgaria, and with the shortest aquatic phase (Arntzen & Wallis 1999). It breeds in various types of stagnant water bodies, such as lakes, swamps, temporary puddles, etc. (Stojanov et al. 2011). ...
We mapped the distribution for the past 18 years (2004-2022) of five protected amphibian species across Bulgaria using a spatial resolution of 100 m 2 in CORINE Land Cover 2018 (CLC). Since the altitudinal distribution and habitat preferences of these species in the country make them potentially vulnerable to agricultural activities, the primary aim was to establish what part of the known records of each species falls within agricultural lands. Results indicated that all five studied species inhabit CLC types falling within the general type "Agricultural areas" (CLC Level 1: 2), with four species predominantly occurring in such regions. In total, three species (Bombina bombina, Triturus cristatus and T. ivanbureschi) had more than 50% of their distribution records in agricultural areas. In another species, Triturus dobrogicus, the percentage was above 40%. The lowest number (under 36%) was for B. variegata. For T. dobrogicus, nearly 32% of all records were concentrated in the CLC Level 3 category "Non-irrigated arable lands". This data suggests that a large percentage of the populations of these protected species across Bulgaria are potentially exposed to agricultural practices such as pesticide use, or crop land aggregation and highlight the need for regional approach for species protection.
... Maletzky et al. (2008b) found no evidence for a natural occurrence of T. carnifex in Germany based on the WI. However, the diagnostic value of WI is rather limited and this issue will only be exacerbated by hybridization (Arntzen & Wallis 1994, 1999. The number of rib-bearing vertebrae (NRV) has been proposed as a more reliable marker for species identification in Crested Newts (Arntzen & Wallis 1994, 1999. ...
... However, the diagnostic value of WI is rather limited and this issue will only be exacerbated by hybridization (Arntzen & Wallis 1994, 1999. The number of rib-bearing vertebrae (NRV) has been proposed as a more reliable marker for species identification in Crested Newts (Arntzen & Wallis 1994, 1999. Still, the diagnostic value of NRV breaks down at hybrid zones , also making it suboptimal to test the potential occurrence of T. carnifex in southeast Germany. ...
While it is generally assumed that only the Northern Crested Newt (Triturus cristatus) occurs in Germany, there are early reports of Crested Newts with features typical of the Italian Crested Newt (T. carnifex) from the Berchtesgadener Land (Bavaria). We study a panel of eight nuclear DNA SNP markers for 26 individual Crested Newts to test if T. carnifex alleles occur in this region. All but two of the studied individuals contain alleles diagnostic for T. carnifex, with the largest percentage of T. carnifex alleles observed in a single individual being 37.5%. The sampled individuals show morphological characteristics typically associated with T. carnifex. We conclude that the natural hybrid zone between the Northern Crested Newt and the Italian Crested Newt reaches further west than previously realized and extends into the extreme southeast of Germany.
... Several studies have shown that salamanders and newts exhibit geographic variation in terms of morphological characteristics, for example, in the genera Hynobius (Matsui et al., 2009;Nishikawa et al., 2007;Tominaga et al., 2005), Echinotriton (Ozaki et al., 2023), Salamandra ( Sunje et al., 2019), Neurergus (Rastegar-Pouyani et al., 2005), Triturus (Arntzen & Wallis, 1999), and Mesotriton (Sotiropoulos et al., 2008). Asian warty newts within the genus Paramesotriton are widely distributed in China and northern Vietnam; however, the geographic variation in their morphology has not been extensively studied. ...
Morphological diversity within organisms can arise from factors other than genetic diversity alone. Local adaptations and combinations of various factors are also involved in shaping morphology. We investigated the relationship between morphological diversity and ecological niche divergence within two related tropical stream-dwelling newt species from Indochina: Paramesotriton deloustali and P. guangxiensis. We identified sexual dimorphism within both species and a significantly larger body size in P. deloustali than in P. guangxiensis. Our findings highlighted that climatic variables strongly influence Asian warty newt distribution, indicating the potential effects of climate change on tropical newt populations. Furthermore , we identified significant intra-and interspecific morphological and niche differentiation across five populations of the two newt species, suggesting that newt morphology is responsive to environmental factors. A significant negative relationship was observed only between ecological niche similarity and geographic distance among various combinations of factors, indicating that the distinct morphology of the study species mirrors ecological adaptation.
... Triturus macedonicus (Karaman, 1922) is a newt species endemic to the Balkan Peninsula that belongs to the wider Triturus cristatus complex (Wielstra and Arntzen 2016;Wielstra et al. 2019) and its distribution spans through seven countries in the southern part of the European continent: Bosnia & Herzegovina, Montenegro, Serbia, Albania, North Macedonia, Greece (Wielstra and Arntzen 2011) and Bulgaria (Naumov and Tzankov 2008). Previously referred to as Triturus carnifex macedonicus and later raised to species level as Triturus macedonicus (Arntzen et al. 2007), the Macedonian newt has distinct morphological features from the other Triturus species (Arntzen and Wallis 1999;Arntzen 2003;Wielstra et al. 2013). Records to date have placed its vertical distribution at elevations up to 1900 m (Speybroeck et al. 2016), 2000m (Valakos et al. 2008) and 2140 m on Mt. ...
Current knowledge of the vertical distribution of Triturus macedonicus places the species at altitudes up to 2140 m. Herein, we report its presence in the alpine lake Gistova at 2360 m on Mt. Grammos, Greece, thus extending the highest altitudinal point for the species, as well as for the Triturus genus. This record showcases the adaptive capacity of the Macedonian newt, which allows it to occupy markedly different environments. More populations may exist at similar or even higher altitudes and their discovery could positively impact conservation efforts.
... In 2005, only in one [13] out of 31 descriptions of new lizard species from 67 most speciose genera the authors provided mitochondrial sequence information. It does not rule out that molecular data were used in the practical taxonomy of these years; however, this usually was done for already described species or elevation of taxonomic status of the earlier described subspecies [14][15][16][17]. From this time, the inclusion of molecular data into species descriptions increased exponentially. ...
Despite the increasing deficit of taxonomic expertise, the number of newly described species since the early 2010s has grown exponentially. This growth is related to the increased use of DNA markers in taxonomic descriptions. However, routine use of DNA markers in taxonomy did not bring practical taxonomy closer to the theory. Species are unique lineages with irreversible evolutionary pathways, and only the presence of distinct populations within the same geographic range, or at least the presence of narrow hybrid zones between the parapatric ranges is a conclusive evidence of evolutionary irreversibility. In the case of allopatric populations, only very high genetic distances, suggesting several tens of millions of years of independent evolution, can be used for validation of species status. This problem cannot be solved by the broader introduction of genomic phylogenies, which also fail to provide robust criteria for evolutionary irreversibility. We can hardly suppose that robust validation of species status is applicable to all or most of hundreds of thousands of animal species, including 20,000 amphibians and reptiles. Instead, practical taxonomy should concentrate on describing recognizable species, maintaining a trade-off between sufficiently detailed descriptions of world biodiversity and the applicability of these descriptions for practical use and metaanalyses, not pretending that formally described species reflect real lineages with independent and irreversible evolutionary pathways. Simultaneously, the non-critical elevation of the taxonomic status of individual geographic populations, contrary to the declared purpose of better-focusing conservation efforts, often has the opposite effect, leaving many formally described taxa outside the conservation umbrella.
... Prema Nacionalnoj klasifikaciji staništa (nadalje u tekstu NKS) te prostornim istraživanja na području PP Kopački rit u sklopu NATURAVITA projekta nalaze se 33 različita tipa staništa u poplavnoj zoni koji su navedeni u Tablica 1 i 40 različitih tipova suhih staništa koji su navedeni u Tablica 2. (2) Područje se proteže od Srbije preko sjeverne Bugarske i južne Rumunjske do delte Dunava te krajnjeg jugoistoka Ukrajine i Moldavije (Jelić i sur., 2015;Macgregor i sur., 1990;Zavadil i sur., 1994;Griffiths, 1996;Ivanović i sur., 2012: Arntzen i sur., 2009b OIB (Griffiths, 1996;Arntzen i Wallis, 1999;Ivanović i sur., 2012). Mužjaci radi razmnožavanja migriraju s kopna u vodu svake godine dok ženke mogu preskočiti koju godinu i ne migrirati u vodu (Jehle i sur., 1995). ...
Kopački rit Nature park is recognised as an important habitat for two species of amphibians and one species of reptile: European fire-bellied toad (Bombina bombina), Danube crested newt (Triturus dobrogicus), european pond turtle (Emys orbicularis). During 2021. to 2022. field surveys were conducted using standardised methods for studying batrachofauna and herpetofauna: visual point survey, funnel traps for amphibians, road transects and linear transect. In addition, a new non – invasive method for detecting elusive species was tested, environmental DNA (eDNA). eDNA is a revolutionary method designed to detect species from water, soil, and air samples that is already being utilized globally to detect specific species. Without direct specimen sampling, this method allows us to determine whether a single species or numerous species are present in a specific area of interest. During field surveys in 2021, 3 amphibian species and 3 reptile species were recorded. The most numerous amphibian group was the Pelophylax species complex (P. ridibundus, P. esculentus, P. kurtmuelleri and P. lessonae), 9 individuals of B. bombina and 4 Lissotriton vulgaris individuals. Reptiles were represented with 48 individuals of E. orbicularis, 6 individuals of Natrix tessellata and one individual of Natrix natrix. In 2022, a total of 87 E. orbicularis were recorded and no B. bombina was observed yet. Regarding reptiles, one individual of the N. natrix and two individuals of the Trachemys scripta were recorded. Futhermore, T. dobrogicus was not detected during the project. Consequently, water samples were collected and filtered from 10 different localities throughout the park to develop and test
the utility of the eDNA method for T. dobrogicus. Research of T. dobrogicus is generally
quite demanding, especially in an inaccessible habitat such as the floodplains of NP Kopački rit. If this method is successful in detecting T. dobrogicus it can also be used to test for the presence and early detection of invasive species in the NP Kopački rit such as T. scripta complex.
... A similar range of variation (two or fewer vertebrae) has been observed in different salamander taxa, and the range of variation seems to be larger in species with higher modal numbers of trunk vertebrae (Peabody and Brodie 1975;Jockusch 1997;Litvinchuk and Borkin 2003;Litvinchuk et al. 2005;Lanza et al. 2006;Slijepčević et al. 2015;Govedarica et al. 2017). In salamanders, the count of vertebral elements may also display variation between different populations ("geographic variation"), among species ("interspecific variation"), between sexes ("sexual dimorphism") and between families (Highton 1960;Jockusch 1997;Arntzen and Wallis 1999;Litvinchuk and Borkin 2003;Lanza et al. 2006;Arntzen et al. 2015). For instance, in different salamander taxa, the number of trunk vertebrae varies significantly from 11 (Salamandridae) to 64 (Amphiumidae) (Duellman and Trueb 1994;Litvinchuk and Borkin 2003). ...
Developmental plasticity, a common pattern in lissamphibian evolution, results in numerous alternative morphologies among species and also within populations. In the present study, a natural population of the salamander Taricha granulosa (Salamandridae) was examined to detect variation in the vertebral count and to identify potential deformities of their vertebral column. The number of trunk vertebrae varied between 11 and 13 and we recorded 58 individuals with 69 anomalous vertebral elements. These anomalies range from congenital malformations (block vertebrae, unilateral bars, hemivertebrae), extra ossifications in the haemal region, to posttraumatic pathologies. Most osseous pathologies were encountered in the caudal region of the axial skeleton. Our data suggest a high frequency of vertebral malformations in salamanders; however, the identification of the exact causes remains challenging.
... It appears to be quite damaging to amphibian populations and even to some fishes (Reshetnikov 2013, and literature quoted therein); in Romania it was found to feed on newts, namely on Lissotriton vulgaris (Telcean and Cicort-Lucaciu 2016), although it can coexist with this species, probably on a short term, before it eliminates it (Covaciu-Marcov et al. 2018). It presents a more severe threat than other introduced fishes as it can induce local extinctions of Triturus dobrogicus (Reshetnikov 2013) a species which otherwise is, unlike other European large newts, generally tolerant of fishes in its reproduction waterbodies (Arntzen and Wallis 1999). ...
The paper presents a review of literature data, supplemented with original observations, on the presence, establishment, distribution and invasive status of alien fish, amphibian and reptile species in Romania. Consistent criteria were followed in defining alien species records, establishment and invasive status. From the 48 alien fish species, 1 fish hybrid, 1 amphibian and 18 reptile species recorded, only 16 fishes and 3 reptiles can be regarded as established. Of these we consider the criteria for invasive status as being probably fulfilled by one fish species ( Perccottus glenii ), and less likely by six more fish species. The presence and the alien status of the one amphibian are debatable. No reptile species can be considered invasive at present.
Ectotherms are particularly sensitive to global warming due to their limited capacity to thermoregulate, which can impact their performance and fitness. From a physiological standpoint, higher temperatures often enhance biological processes that can induce the production of reactive oxygen species and result in a state of cellular oxidative stress. Temperature alters interspecific interactions, including species hybridization. Hybridization under different thermal conditions could amplify parental (genetic) incompatibilities, thus affecting a hybrid's development and distribution. Understanding the impact of global warming on the physiology of hybrids and particularly their oxidative status could help in predicting future scenarios in ecosystems and in hybrids. In the present study, we investigated the effect of water temperature on the development, growth and oxidative stress of two crested newt species and their reciprocal hybrids. Larvae of Triturus macedonicus and T. ivanbureschi, and their T. macedonicus-mothered and T. ivanbureschi-mothered hybrids were exposed for 30 days to temperatures of 19°C and 24°C. Under the higher temperature, the hybrids experienced increases in both growth and developmental rates, while parental species exhibited accelerated growth (T. macedonicus) or development (T. ivanbureschi). Warm conditions also had different effects on the oxidative status of hybrid and parental species. Parental species had enhanced antioxidant responses (catalase, glutathione peroxidase, glutathione S-transferase and SH groups), which allowed them to alleviate temperature-induced stress (revealed by the absence of oxidative damage). However, warming induced an antioxidant response in the hybrids, including oxidative damage in the form of lipid peroxidation. These findings point to a greater disruption of redox regulation and metabolic machinery in hybrid newts, which can be interpreted as the cost of hybridization that is likely linked to parental incompatibilities expressed under a higher temperature. Our study aims to improve mechanistic understanding of the resilience and distribution of hybrid species that cope with climate-driven changes.
Among amphibians, adults have traditionally been identified in capture-mark-recapture studies using invasive marking techniques with associated ethical, cost and logistical considerations. However, species in this group may be strong candidates for photo-identification based on natural skin features that removes many of these concerns, with this technique opening up opportunities for citizen scientists to be involved in animal monitoring programs. We investigated the feasibility of using citizen science to distinguish between individuals of an Australian anuran (the sandpaper frog, Lechriodus fletcheri ) based on a visual analysis of their natural skin features. We collected photographs of marked individuals in the field over three breeding seasons using a smartphone device. This photo-database was used to create an online survey to determine how easily members of the general public could photo-match individuals by a comparison of two facial skin features; black banding that runs horizontally above the tympanum and a background array of tubercles present in this region. Survey participants were provided with 30 closed, multiple choice questions in which they were asked to match separate images of a query frog from small image pools of potential candidate matches. Participants were consistently able to match individuals with a low matching error rate (mean ± SD of 26 ± 5) despite the relatively low quality of photographs taken from a smartphone device in the field, with most query frogs being matched by a majority of participants (mean ± SD of 86.02 ± 9.52%). These features were found to be unique and stable among adult males and females. Thus, photo-identification is likely to be a valid, non-invasive method for capture-mark-recapture for L. fletcheri , and likely many anurans that display similar facial skin features. This may become an important alternative to artificial marking techniques, with the challenges of manual photo-matching reduced by spreading workloads among members of the public that can be recruited online.
Biogeographic characteristic of nine taxon-area-cladograms of various Circum-Mediterranean terrestrial animal groups are compared. Correlation with palaeogeograhic reconstructions suggests Oligocene and especially Miocene diversification within these groups. The oldest faunal elements are found in the western part of the region which dates from well before the Miocene. Origin of younger lineages is considered linked with the Late Oligocene-Early Miocene formation of a landmass which separated Tethys and Paratetys. Major divergence is hypothesized to have been achieved by subsequent vicariant and distributional events throughout the Mediterranean during the Miocene. The palaeo-biogeographic correlation results in estimates of the ages of lineages for the newt genus Triturus which largely correspond to the estimates obtained from various biochemical and molecular studies.
The general morphology of gymnophionans, i.e., their body proportions, total number of vertebrae, and variation in vertebral length along the vertebral column, are compared. The biometrical data derive from the monograph of Taylor (1968), supplemented by data from X-rays of specimens from several museum collections. The structural features allow definition of morphological types ranging from extremely stout to thread-like. Consideration of the locomotor role played by the trunk in limbless vertebrates suggests that these types may correspond to morpho-functional ones. However, lack of information about ecological conditions and actual locomotor behavior of most of the Gymnophiona still prevents a test of this hypothesis. The diversity here revealed suggests that Gymnophionan evolution reflects adaptation to a wide range of biotopes, from humid dense soils, the litter and felted rootlets of the rain forest floor, to the aquatic medium.
To understand the evolutionary significance of geographic variation, one must identify the factors that generate phenotypic differences among populations. I examined the causes of geographic variation in and evolutionary history of number of trunk vertebrae in slender salamanders. Batrachoseps (Caudata: Plethodontidae). Number of trunk vertebrae varies at many taxonomic levels within Batrachoseps. Parallel clines in number occur along an environmental gradient in three lineages in the Coast Ranges of California. These parallel clines may signal either adaptation or a shared phenotypically plastic response to the environmental gradient. By raising eggs from 10 populations representing four species of Batrachoseps, I demonstrated that number of trunk vertebrae can be altered by the developmental temperature; however, the degree of plasticity is insufficient to account for geographic variation. Thus, the geographic variation results largely from genetic variation. Number of trunk vertebrae covaries with body size and shape in diverse vertebrate taxa, including Batrachoseps. I hypothesize that selection for different degrees of elongation, possibly related to fossoriality, has led to the extensive evolution of number of trunk vertebrae in Batrachoseps. Analysis of intrapopulational variation revealed sexual dimorphism in both body shape and number of trunk vertebrae, but no correlation between these variables in either sex. Females are more elongate than males, a pattern that has been attributed to fecundity selection in other taxa. Patterns of covariation among different classes of vertebrae suggest that some intrapopulational variation in number results from changes in vertebral identity rather than changes in segmentation.
Interspecific hybrids have been proposed to have reduced developmental stability in comparison to their parental species because the parental genomes have not undergone selection for the maintenance of developmental stability when they occur together. We present data from four interspecific hybrids of salmonid fishes that support this view. Natural hybrids of bull trout (Salvelinus confluentus) with brook trout (Salvelinus fontinalis) and laboratory hybrids of rainbow trout (Salmo gairdneri) with Yellowstone (Salmo clarki bouvieri), westslope (S. c. lewisi), and coastal (S. c. clarki) cutthroat trout all have higher levels of fluctuating asymmetry than either of their parental species raised in the same environment. Thus, the hybrids have reduced developmental stability. The hybrids do not have meristic counts intermediate to the counts of the parental species. The hybrids usually have counts as high as the species with the higher count for those characters that differ between the parental species and often have higher counts for those characters that do not differ between the parental species. We suggest that the tendency for interspecific hybrids to have high meristic counts may be related to differences between the species in the length and timing of the developmental periods during which the counts of the characters are determined.
A review of fossil evidence on the rates of limb loss in tetrapods indicates that millions of years are required for complete loss of external traces of limbs. Morphological series of intermediate stages of limb loss within genera in the lizard families Scincidae and Teiidae show that there are evolutionary pathways of body elongation and reduction of limb size relative to skull length, accompanied by loss of limb elements beginning distally. Evolutionary elongation of the lizard body occurs through an increase in the coefficient of allometric growth of the body with respect to the skull, which precedes structural reduction of the limbs. A review of embryological studies of limbed and limbless forms suggests that in amniotes the distal to proximal sequence of structural reduction evolves by the progressively earlier onset of cell death which usually occurs to form the spaces between the digits, in conjunction with the normal proximo-distal sequence of determination of mesodermal elements in limb development. Following a presentation of data on digital variation in lizards, genetic studies of digit loss and polydactyly are summarized which indicate a polygenic influence on structural variation. Using these data, mathematical models are constructed which show that weak selection pressures can produce geologically rapid structural changes. The mechanism of reexpression of long lost structures of the limb (such as cetacean pelvic limbs and atavistic digits in the horse, dog, and guinea pig) is considered in a view of information on appendicular mutations in the mouse.
Relationships among size, number of presacral vertebrae, morphology and life history in members of the Pariocela section of the genus Eumeces were investigated. Presacral vertebral counts range from 26 in the largest, most stout-bodied species to 33 in the smallest, most elongate species. Female abdominal growth is positively allometric in all species, but strength of allometry is inversely correlated with size. Small, elongate Mexican montane species achieve a level of morphological development typical of subadults of larger forms, and reach sexual maturity in less time. They are thus progenetic (larger, slower maturing forms showing the primitive condition), and small size is proposed to be an adaptation to the short montane growing season. Abdominal elongation is interpreted as a means of maintaining a minimum critical clutch size, given a functionally constrained minimum neonate size and physical limitations on abdominal volume in a juvenile-sized adult.
Twenty-seven islands in the Lesser Antilles contain either 1 or 2 species of Anolis lizards. On 9 of the 10 2-species islands, the species differ substantially in size; 16 of the 17 one-species islands harbor an intermediate-sized species. Two processes could produce such a pattern: size adjustment (or character displacement), in which similar-sized species evolve in different directions in sympatry; and size assortment, in which only different-sized species can successfully colonize the same island together. Size evolution appears rare (a minimum of 4-7 instances of substantial size evolution). In the northern (but not the southern) Lesser Antilles, size change was significantly greater when a descendant taxon occurred on a 2-species island and its hypothetical ancestor occurred on a 1-species island, supporting the size adjustment hypothesis, though size adjustment might have occurred only once. The relative rarity of size evolution suggests that size assortment might be responsible for non-random patterns. Similar-sized species might not coexist because they interbreed and coalesce into one gene pool. Competitive exclusion is probably responsible for the pattern of size assortment in the N Lesser Antilles; both competitive exclusion and interbreeding of closely related species of similar size might be responsible for the patterns evident in the S Lesser Antilles. -from Author
The sandswimming, Australian scincid lizard genus Lerista is the best example of limb reduction in tetrapods in that it comprises an extensive and finely graded morphocline within a group of 51 closely related species. This paper analyzes variation in the number of phalanges and presacral vertebrae within populations and among species. Within populations, phalangeal number varies little and variation is usually symmetrical within individuals. The number of presacral vertebrae is sexually dimorphic, with females averaging 0.4-2.0 more than males. Among species there is a strong, curvilinear, inverse relationship between the number of phalanges and the number of presacral vertebrae. The interspecific morphoclines of phalangeal complements based on the total number of phalanges show that digits in both the manus and pes are lost in the order 1 > 5 > 2 > 3 > 4. Such morphoclines are perfectly linear except at one point in the pes where the series branches to accommodate two mutually exclusive configurations. If these morphoclines represent phylogenetic reductions and if phylogenetic reductions are hypothesized to be globally arrested stages of a basic developmental pattern, then one of these pes configurations must constitute an exception to this generalization. At least one other observed configuration is also likely to be outside a basic, global ontogenetic sequence for the genus.
A synthesis of all known data on the crested newt group assigns the Balkan peninsula as the center of origin or, at least, the area where the basic lineage of its species was limited in the late Miocene. According to the recent literature, the geological structure of the Balkan region changed considerably during the Tertiary. These geological processes could have had a considerable impact on crested newt divergence and on the recent distribution of species. Using the number of rib-bearing vertebrae (RBVN), recently suggested as a simple and powerful tool for distinguishing four taxa of the T cristatus superspecies, we analysed 36 population samples collected all over former Yugoslavia. The hypothesised recent distribution of the crested newt species, based on frequency distribution of RBVN, appears to correspond well to neotectonic events in the past.