Skeletal repatterning enhances the protective capacity of the shell in African hinge‐back tortoises (Kinixys)

Changes in the structural association of skeletal traits are crucial to the evolution of novel forms and functions. In vertebrates, such rearrangements often occur gradually and may precede or coincide with the functional activation of skeletal traits. To illustrate this process, we examined the ontogeny of African hinge-back tortoises (Kinixys spp.). Kinixys species feature a moveable “hinge” on the dorsal shell (carapace) that enables shell closure (kinesis) when the hind limbs are withdrawn. This hinge, however, is absent in juveniles. Herein, we describe how this unusual phenotype arises via alterations in the tissue configuration and shape of the carapace. The ontogenetic repatterning of osseous and keratinous tissue coincided with shifts in morphological integration and the establishment of anterior (static) and posterior (kinetic) carapacial modules. Based on ex vivo skeletal movement and raw anatomy, we propose that Kinixys employs a “sliding hinge” shell-closing system that overcomes thoracic rigidity and enhances the protective capacity of the carapace. Universal properties of the vertebrate skeleton, such as plasticity, modularity, and secondary maturation processes, contributed to adaptive evolutionary change in Kinixys. We discuss a hypothetical model to explain the delayed emergence of skeletal traits and its relevance to the origins of novel form-to-function relationships.info:eu-repo/semantics/publishedVersio

How many species of angulate tortoises occur in Southern Africa? (Testudines: Testudinidae: Chersina)

Using range-wide sampling and 1,143 bp of mtDNA (cytochrome b gene) and 14 microsatellite loci, we examined genetic differentiation in the widely distributed Southern African angulate tortoise (Chersina angulata). We found evidence for two genealogical lineages that differ in both genetic marker systems and their preferred habitat conditions. According to a fossil-calibrated molecular clock for all African tortoise lineages using 1,870 bp mitochondrial and 1,416 bp nuclear DNA, the two lineages of C. angulata diverged in the Pliocene (approx. 3.8 million years ago). Species distribution models reveal that the ranges of the two lineages shifted little since the Last Glacial Maximum, which is in agreement with the demographic population descriptors suggestive of stationary populations that did not experience expansion. One lineage occurs in the west, and the other in the south of the extant distribution range. In the geographic contact zone, the two lineages hybridize extensively, providing evidence for their conspecificity under the biological species concept. Each lineage could be recognized as a distinct subspecies, but the ill-defined geographic origins of the type material of the available names prevent their identification with any taxon

Leopard tortoises in southern Africa have greater genetic diversity in the north than in the south (Testudinidae)

In contrast to mammals, little is known about the phylogeographic structuring of widely distributed African reptile species. With the present study, we contribute data for the leopard tortoise (Stigmochelys pardalis). It ranges from the Horn of Africa southward to South Africa and westwards to southern Angola. However, its natural occurrence is disputed for some southern regions. To clarify the situation, we used mtDNA sequences and 14 microsatellite loci from 204 individuals mainly from southern Africa. Our results retrieved five mitochondrial clades; one in the south and two in the north-west and north-east of southern Africa, respectively, plus two distributed further north. Using microsatellites, the southern clade matched with a well-defined southern nuclear cluster, whilst the two northern clades from southern Africa corresponded to another nuclear cluster with three subclusters. One subcluster had a western and central distribution, another occurred mostly in the north-east, and the third in a small eastern region (Maputaland), which forms part of a biodiversity hotspot. Genetic diversity was low in the south and high in the north of our study region, particularly in the north-east. Our results refuted that translocations influenced the genetic structure of leopard tortoises substantially. We propose that Pleistocene climatic fluctuations caused leopard tortoises to retract to distinct refugia in southern and northern regions and ascribe the high genetic diversity in the north of southern Africa to genetic structuring caused by the survival in three refuges and subsequent admixture, whereas tortoises in the south seem to have survived in only one continuous coastal refug

Phylogeny and phylogeography of chelonians from sub-Saharan Africa—A review of current knowledge in tribute to Margaretha D. Hofmeyr

Species-level phylogeny and especially phylogeography of African chelonians is a comparatively under-studied field of research. We review the current knowledge of phylogeny and phylogeography, highlight congruence of spatial phylogeographic patterns amongst chelonians and other taxa and suggest future research directions to address gaps in knowledge. Our review shows that phylogeographic and phylogenetic investigations have led to unexpected findings. For example, for Pelomedusa, a putatively wide-ranging monotypic terrapin genus, cryptic diversity was revealed, with more than ten species being uncovered. The formerly recognized tortoise genus Homopus sensu lato was found to be paraphyletic with respect to Chersina. To resolve this situation, Homopus was restricted to the four-toed species H. areolatus and H. femoralis and the genus Chersobius was resurrected for the five-toed species C. boulengeri, C. signatus, and C. solus. Three previously recognized taxa were shown to be invalid, viz. the putatively extinct terrapin species Pelusios seychellensis and the tortoise subspecies Chersobius signatus cafer and Stigmochelys pardalis babcocki. Together with taxonomy, the knowledge of phylogeographic structuring sets a solid foundation for conservation measures and allows the identification of Management and Conservation Units. However, the current legislation, in particular the enforcement of the Nagoya Protocol under the Convention of Biological Diversity (CBD), has largely halted research on widely distributed taxa and turned the well-intended concept of Access and Benefit Sharing into a major impediment for conservation and research. The current situation leads for many species to a continued usage of outdated and incorrect taxonomic classifications resulting in an error cascade of conservation decisions. This is counterproductive to the aims of the CBD, that is, the protection of biodiversity. Sequencing historical DNA from museum specimens using aDNA approaches could be a short-term approach to mitigate, but not solve, this impediment

Important new records of Pelomedusa species for South Africa and Ethiopia

Because of a recent taxonomic revision, the species identity of helmeted terrapins (Pelomedusa) became unclear in many regions of their wide distribution range. Based on mtDNA sequence data, here we present the first record of Pelomedusa subrufa sensu stricto for the South African province of Mpumalanga. In South Africa, this species was previously known only from a single record in the province of Limpopo. In addition, we provide evidence for the occurrence of at least two distinct Pelomedusa species in Ethiopia. A sample from southern Ethiopia (Omo Region) turned out as P. neumanni, while another sample from Koka Lake (Oromia Region, central Ethiopia) represents P. somalica. Also a historical museum specimen from Ethiopia, most likely collected south of the Shebelle River (Oromia Region), belongs to P. somalica. However, these two Ethiopian specimens of P. somalica represent highly distinct genetic lineages, which may actually correspond to two different species

Pregled jedanaest kratkotrajnih istraživanja faune gmazova na području zapadnog Balkana

In this paper we present distributional data for reptiles from different localities in the Western Balkans. During an 11 year period (2002-2012) we collected new data in the frame of spring student research camps organized by the Biology Students’ Society (DŠB). Surveys were conducted by members of the herpetological groups that were mostly biology students. Surveys were located on five islands Dugi otok, Brač, Korčula, Mljet, and Pag, one peninsula Pelješac (Croatia), in the continental area around Kamenovo and Lake Skadar (Montenegro), Dojran Lake (Macedonia), at lower Neretva Delta (Croatia) and around Niš (Serbia). Altogether 34 different reptile species were recorded in the surveys. The species lists comprised of 7-22 different species per single locality. The highest reptile biodiversity was recorded around Dojran Lake in Macedonia.U radu se prikazuju distribucijski podatci za gmazove sa različitih lokaliteta na području zapadnog Balkana. Tijekom razdoblja od 11 godina (2002. – 2012.) prikupili smo nove podatke u okviru studentskih istraživačkih kampova organiziranih od strane Društva studenata biologije (DSB). Istraživanja su provedena od strane pripadnika herpetološke sekcije koju većinom čine studenti biologije. Istraživanja su provedena na pet otoka, Dugi otok, Brač, Korčula, Mljet i Pag, jednom poluotoku, Pelješac (Hrvatska), na kontinentalnom području oko Kamenova i Skadarskog jezera (Crna Gora), okolici Dojranskog jezera (Makedonija), na području donjeg dijela rijeke Neretve (Hrvatska) i oko grada Niša (Srbija). Istraživanjem je ukupno zabilježeno 34 različite vrste gmazova. Na pojedinim lokalitetima zabilježeno je od 7 do 22 vrste gmazova, a najveća raznolikost zabilježena je oko Dojranskog jezera u Makedoniji

Mitochondrial ghost lineages blur phylogeography and taxonomy of Natrix helvetica and N. natrix in Italy and Corsica

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Where are you from, stranger? The enigmatic biogeography of North African pond turtles (Emys orbicularis) .

Abstract The European pond turtle (Emys orbicularis) is a Nearctic element in the African fauna and thought to have invaded North Africa from the Iberian Peninsula. All North African populations are currently identified with the subspecies E. o. occidentalis. However, a nearly range-wide sampling in North Africa used for analyses of mitochondrial and microsatellite DNA provides evidence that only Moroccan populations belong to this taxon, while eastern Algerian and Tunisian pond turtles represent an undescribed distinct subspecies. These two taxa are most closely related to E. o. galloitalica with a native distribution along the Mediterranean coast of northern Spain through southern France to western and southern Italy. This group is sister to a clade comprising several mitochondrial lineages and subspecies of E. orbicularis from Central and Eastern Europe plus Asia, and the successive sisters are E. o. hellenica and E. trinacris. Our results suggest that E. orbicularis has been present in North Africa longer than on the Iberian Peninsula and that after an initial invasion of North Africa by pond turtles from an unknown European source region, there was a phase of diversification in North Africa, followed by a later re-invasion of Europe by one of the African lineages. The differentiation of pond turtles in North Africa parallels a general phylogeographic paradigm in amphibians and reptiles, with deeply divergent lineages in the western and eastern Maghreb. Acknowledging their genetic similarity, we propose to synonymize the previously recognized Iberian subspecies E. o. fritzjuergenobsti with E. o. occidentalis sensu stricto. The seriously imperiled Moroccan populations of E. o. occidentalis represent two Management Units different in mitochondrial haplotypes and microsatellite markers. The conservation status of eastern Algerian pond turtles is unclear, while Tunisian populations are endangered. Considering that Algerian and Tunisian pond turtles represent an endemic taxon, their situation throughout the historical range should be surveyed to establish a basis for conservation measures

Chelonian challenge: three alien species from North America are moving their reproductive boundaries in Central Europe

Biological invasions by alien species have substantial economic impacts and are a major driver of the ongoing decline and loss of biodiversity. Through humans, the North American pond slider (Trachemys scripta) has acquired a global distribution over the last decades and is currently listed among the worst invasive reptile species. However, in more recent times, other freshwater chelonian species have increasingly been recorded far outside their native distribution ranges as well, not only on the same continent but also on others. Despite that, the impact of alien chelonians on their respective new ecosystems remains unclear. The long-term effects and severity of impacts of alien populations mostly depend on whether they ultimately succeed in establishing themselves. This is not entirely resolved for chelonians in Central Europe. To answer that, we investigated wild populations of three non-native chelonian species from North America in Germany (Pseudemys concinna, Graptemys pseudogeographica and Trachemys scripta) applying population genetic approaches. We revealed the successful reproduction of all three species in Germany and provide the very first record for the reproduction of P. concinna and G. pseudogeographica in a temperate continental climate zone outside their native distribution. Based on our unambiguous evidence of natural reproduction, we call for dedicated studies to verify how widespread established populations are and to investigate the existing and potential impacts of all three species in a range of ecosystems along a climatic gradient. Such data is urgently needed to revise the current risk assessments of non-native chelonians, especially in Central European countries