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Publications (149)
The phylogeographic structure of the monotypic endemic southern African angulate tortoise Chersina angulata was investigated throughout its distribution with the use of partial sequences from three mtDNA loci (COI, cyt b and ND4). Phylogeographic and phylogenetic structuring obtained for the three mtDNA markers were highly congruent and suggested t...
Climate change models predict that the range of the world's smallest tortoise, Homopus signatus signatus, will aridify and contract in the next decades. To evaluate the effects of annual variation in rainfall on the growth of H. s. signatus, we recorded annual growth rates of wild individuals from spring 2000 to spring 2004. Juveniles grew faster t...
A total of 586 reptiles, belonging to 35 species and five subspecies, were examined in surveys aimed at determining the species spectrum and geographic distribution of ticks that infest them. Of these reptiles 509 were tortoises, 28 monitor or other lizards, and 49 snakes. Nine ixodid tick species, of which seven belonged to the genus Amblyomma, an...
Previous studies have suggested that nocturnal and diurnal species of rodents differ in their circadian responses to light including phase shifts and early gene expression. Rhabdomys pumilio, the four-striped field mouse, is diurnal both in nature and in the laboratory. We studied in this species the response of the suprachiasmatic nucleus (SCN) to...
Although humans are diurnal in behaviour, animal models used for the study of circadian rhythms are mainly restricted to nocturnal rodents. This study focussed on the circadian behaviour of a rodent from South Africa that has a preference for daylight, the four-striped field mouse, Rhabdomys pumilio. In order to characterise the behavioural pattern...
We began developing our Geometric Tortoise Ecosystem Preserve in 2015. At the same time, we began a mark–recapture study to detect changes in the population size through time to inform our management practices. We now have data through 2021. Mark–recapture analysis gives a population size of between 800 and 1200 individuals. It is the last remainin...
This study examined population ecology parameters for a southern population of the tent tortoise (Psammobates tentorius tentorius) in the Karoo. We found a relatively low density of tortoises (49 tortoises/km²) skewed to adults with a 1:1 sex ratio. The tortoises' contrasting dark and light carapacial patterns create crypsis with the disruptive sha...
Correction to: Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa
Sub-Saharan Africa harbours an outstanding diversity of tortoises of which the leopard tortoise Stigmochelys pardalis is the most widespread. Across its’ range the species is impacted by habitat transformation, over-collection for human consumption and the pet trade, road mortality, and electrocution by electric fences. Most leopard tortoises in so...
This study used codon analysis (dN/dS and Tv/Ti) to investigate selection pressure and genetic structure in the highly polymorphic Psammobates tentorius species complex, and amino acid sequences to construct a phylogeny tree for it. Our results revealed a strong selection signal at node ‘C2 + C3’, possibly driven by aridity intensification resultin...
Background
Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspo...
We examined genetic differentiation in the highly polymorphic and taxonomically confusing tent tortoise ( Psammobates tentorius ) species complex in southern Africa, using three types of molecular markers (nDNA, mtDNA and microsatellite DNA) and morphological data. The Approximate Bayesian Computation based simulation analyses advocated an alternat...
The phylogeographic structure of the monotypic endemic southern African angulated tortoise Chersina angulata was investigated throughout its distribution with the use of partial sequences from three mtDNA loci (COI, cyt b and ND4). Phylogeographic and phylogenetic structuring obtained for the three-mtDNA markers were highly congruent and suggested...
REPRODUCTION OF THE SMALLEST TORTOISE, THE NAMAQUALAND SPECKLED PADLOPER, HOMOPUS SIGNATUS SIGNATUS
VICTOR J. T. LOEHR, BRIAN T. HENEN AND MARGARETHA D. HOFMEYR2
The smallest tortoise, Homopus signatus, is inadequately protected, and information on its reproductive ecology can facilitate effective conservation. We combined X-ray radiography and ul...
Turtles and tortoises (chelonians) have been integral components of global ecosystems for about 220 million years and have played important roles in human culture for at least 400,000 years. The chelonian shell is a remarkable evolutionary adaptation, facilitating success in terrestrial, freshwater and marine ecosystems. Today, more than half of th...
Background
Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius covers two of the 25 biodiversity hotspots of souther...
Background: Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotsp...
Background Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspo...
Background Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspo...
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. Accor...
We assessed genetic differentiation and habitat suitability for Homopus areolatus during current and Last Glacial Maximum (LGM) conditions. The ND4 locus retrieved two monophyletic mtDNA clades with lower diversity in clade 1, in the west, than in clade 2, in the south-east. Clade 1 showed a north–south and clade 2 a west-to-east genetic divergence...
The Lobatse Hinge-back Tortoise, Kinixys lobatsiana (Power, 1927), has a small distribution range in northern South Africa and adjacent Botswana. Local populations have been fragmented by degradation and destruction of suitable habitat, resulting in this species being listed as Vulnerable by IUCN. Here, the geographic distribution of K. lobatsiana...
The five extinct giant tortoises of the genus Cylindraspis belong to the most iconic species of the enigmatic fauna of the Mascarene Islands that went largely extinct after the discovery of the islands. To resolve the phylogeny and biogeography of Cylindraspis, we analysed a data set of 45 mitogenomes that includes all lineages of extant tortoises...
Kinixys spekii has a wide distribution range across sub-Saharan Africa, having been reported from Angola, Botswana, Burundi, the Democratic Republic of the Congo, eSwatini, Kenya, Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia, and Zimbabwe. Kinixys spekii inhabits savannah and dry bushveld habitats and was previously considered an inl...
Biogeographic analyses including our complete data set suggest that the ancestor of Cylindraspis lived in Africa and island-hopped to the Mascarenes circumventing Madagascar. According to our data, the Mascarene giant tortoises were definitely not introduced by humans.
Records from the putative gap in the distribution range of Pelomedusa galeata in western South Africa provide evidence for the occurrence of helmeted terrapins in those areas. Further research is needed to reveal the genetic and taxonomic identity of these populations.
Pelusios sinuatus is distributed in East Africa from southern Ethiopia and Somalia to northeastern South Africa. Inland it reaches westernmost Zimbabwe, Rwanda, and Burundi. Despite this wide range, which spans in north-south direction across 3,500 km and in east-west direction more than 1,500 km, no geographic variation has been described. However...
The high level of phenotypic diversity in southern African tent tortoises (Psammobates tentorius complex) has for decades prevented systematists from developing a stable taxonomy for the group. Here, we used a comprehensive DNA sequence dataset (mtDNA: Cytb, ND4, ND4 adjacent tRNA-His, and tRNA-Ser, 12S, 16S; and nDNA: PRLR gene) of 455 specimens,...
Supporting information Supplementary Figures Figure S1. Map showing the distribution ranges of the three currently recognised subspecies of Psammobates tentorius based on previous records: P. t. tentorius (green), P. t. verroxii (blue) and P. t. trimeni (red). The data are a combination of own records, Port Elizabeth Bayworld Museum records, Pretor...
This note documents four species of plant consumed by the Critically Endangered Geometric Tortoise, Psammobates geometricus.
Compared to the global average, extinction risk for mainland African reptiles, particularly for South Africa, appears to be relatively low. Despite this, African reptiles are under threat primarily due to habitat loss as a result of agriculture, resource extraction, and urbanisation, and these pressures are expected to increase into the future. Sou...
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 dis...
We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisiona...
We used ultrasonography and radiography to evaluate whether body size (BS), body condition (BC) and environmental factors influenced reproductive investments by Chersobius signatus in September 2000 and from September 2003 to November 2004. Follicle volume increased with increasing BS, BC and rainfall but decreased with increasing temperature. Egg...
Based on rangewide sampling and three mitochondrial and two nuclear markers (together up to 1,850 bp and 1,840 bp, respectively), we examine the phylogeography of two helmeted terrapin species (Pelomedusa galeata and P. subrufa sensu stricto) and infer shifts of climatically suitable spaces since the Last Glacial Maximum using a modeling approach....
Alignment cyt b sequences
Studied samples and ENA accession numbers for DNA sequences
Alignment 12S rRNA sequences
Alignment ND4 + tRNA sequences
Alignment of concatenated mtDNA for TCS network
Since 1957, all padlopers were considered Homopus, which was an anomaly, because only two species have four claws on the front and hind limbs. The revival of the genus Chersobius for the five-toed species (signatus, boulengeri and solus) now limits Homopus to the four-toed species (areolatus and femoralis). Molecular data indicate that Homopus is p...
This book presents a brief summary of the 25th most endangered tortoise and turtle species. The summary includes a specimen picture, common and scientific names, endangered status, distribution, main causes for population decrease, and on going conservation strategies
This book presents a brief summary of the 25th most endangered tortoise and turtle species. The summary includes both common and scientific names, distribution, causes of population decrease, and conservation strategies.
To help assess habitat requirements of Critically Endangered geometric tortoises, we used thread-trailing to measure daily activity, movements and refugia of adult Psammobates geometricus in autumn and spring 2002. We found strong differences between seasons, and effects of weather, individuals and sex. The high activity was consistent with mild we...
Body condition and haematological indices provide powerful information when assessing wildlife health. Reference intervals for these indices can facilitate wildlife management, and would benefit initiatives to save the Critically Endangered geometric tortoise (Psammobates geometricus). We collected data from 126 geometric tortoises to establish bas...
Land transformation reduced the habitat of Psammobates geometricus to small isolated fragments, rendering the species vulnerable to extinction. Field biologists often use erythrocyte metrics to assess wildlife health but need baseline values to distinguish normal variations from disease or chronic stress. Here we characterise erythrocyte types and...
Africa, inclusive of the West Indian Ocean islands, harbours 11 of the world’s 16 extant testudinid
genera. Fossil records indicate that testudinids originated in Asia and dispersed first
to North America and Europe (Early Eocene) and later to Africa (Late Eocene). We used
mitochondrial (1870 bp) and nuclear (1416 bp) DNA sequence data to assess wh...
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...
We studied morphological traits of Psammobates oculifer over its range to evaluate patterns in sexual size
dimorphism (SSD) and geographic variation. Females were larger than males for 40 of the 44 characters measured and the growth trajectories of female parameters, scaled to body size (ANCOVA and MANCOVA on carapace length), most often followed j...
Recent research has shown that the helmeted terrapin (Pelomedusa subrufa), a species that occurs throughout sub-Saharan
Africa, in Madagascar and the southwestern Arabian Peninsula, consists of several deeply divergent genetic lineages. Here
we examine all nominal taxa currently synonymized with Pelomedusa subrufa (Bonnaterre, 1789) and provide mit...
Using nearly range-wide sampling, we analyze up to 1848 bp of mitochondrial DNA of 183 helmeted terrapins and identify a minimum of 12 deeply divergent species-level clades. Uncorrected p distances of these clades equal or clearly exceed those between the currently recognized species of Pelusios, the genus most closely related to Pelomedusa. We cor...
The availability of suitable refuges to buffer temperature extremes may be a critical determinant in the distribution of arid-zone ectotherms. We studied refuge selection of Kalahari tent tortoises over five seasons in two vegetation types to assess how seasonal climate change, vegetation type, and the size difference between sexes influence refuge...
We studied the ecology of Psammobates oculifer over 13 months near Kimberley, South Africa, to ascertain if the population's life history traits conform to chelonian patterns in arid environments. Capture rates were highest in spring and lowest in winter when environmental conditions were respectively most and least favourable for tortoise activity...
Context. Given the immense impact of wildlife trade, disease and repatriations on populations, health assessments can provide powerful forensic material to help convict wildlife poachers and minimise risks of releasing unhealthy wildlife. Aims. We aimed to use reference ranges to assess the health of confiscated tortoises, to illustrate forensic ap...
We examine the phylogeography, phylogeny and taxonomy of hinge-back tortoises using a comprehensive sampling of all currently recognized Kinixys species and subspecies and sequence data of three mitochondrial DNA fragments (2273 bp: 12S rRNA, ND4 + adjacent DNA coding for tRNAs, cytb) and three nuclear loci (2569 bp: C-mos, ODC, R35). Combined and...
We examine the phylogeography, phylogeny and taxonomy of hinge-back tortoises using a comprehensive sampling of all currently recognized Kinixys species and subspecies and sequence data of three mitochondrial DNA fragments (2273 bp: 12S rRNA, ND4 + adjacent DNA coding for tRNAs, cytb) and three nuclear loci (2569 bp: C-mos, ODC, R35). Combined and...
Psammobates geometricus has a limited distribution in the southwestern Cape, South Africa, where it occurs in small habitat fragments separated by agricultural and urban developments. Space use and its determining factors thus represent critical information for the effective conservation of this species. We used radiotelemetry and thread-trailing t...
Although many tortoise species inhabit drought-prone regions with potentially limiting resources, these species have long, iteroparous lives. To assess reproductive responses to variation in rainfall, and to understand interactions among egg size, body size, body condition, and rainfall, we studied egg production in the Namaqualand Speckled Padlope...
Fritz, U., Branch, W. R., Hofmeyr, M. D., Maran, J., Prokop, H., Schleicher, A., Široký, P., Stuckas, H., Vargas-Ramírez, M., Vences, M. & Hundsdörfer, A. K. (2010). Molecular phylogeny of African hinged and helmeted terrapins (Testudines: Pelomedusidae: Pelusios and Pelomedusa). —Zoologica Scripta, 40, 115–125.
With 18 currently recognised species...
Although many tortoise species inhabit drought-prone regions with potentially limiting resources, these species have long, iteroparous lives. To assess reproductive responses to variation in rainfall, and to understand interactions among egg size, body size, body condition, and rainfall, we studied egg production in the Namaqualand Speckled Padlope...
This study investigated the systematics and phylogeography of a threatened tortoise of South Africa, the speckled padloper Homopus signatus. Sixty three specimens were collected from 17 localities that covered the distributional range of the two subspecies in western South Africa and a north-eastern population that was recently discovered near Pofa...
Histological analysis of the ovaries and the presence of multiple modes in oocyte size frequency distribution of Cape hake Merluccius capensis and M. paradoxus indicates that they are serial spawners. Batch fecundity, calculated by means of the "hydrated oocyte method", was positively correlated to ovary-free fish mass and total fish length. The me...
We investigated the phylogeographic differentiation of the widely distributed African helmeted terrapin Pelomedusa subrufa based on 1503 base pairs of mitochondrial DNA (partial cyt b and ND4 genes with adjacent tRNAs) and 1937 bp of nuclear DNA (partial Rag1, Rag2, R35 genes). Congruent among different analyses, nine strongly divergent mitochondri...
We do not know whether the availability of food plants is the primary factor enabling Angulate Tortoises to inhabit a wide variety of habitats along the southern and western coasts of South Africa. Here we used focal observations to study the diet of Angulate Tortoises over four seasons at two distinct sites in the southwestern Cape, the West Coast...
The reproductive cycle and egg production of Chersina angulata females, maintained under natural climate conditions, were studied over 29 months using ultrasonography. Angulate tortoises initiated egg production in February (late summer) and were gravid through most of the year. A short nongravid period in January indicates a cyclic rather than con...
Several climate models predict that the western Succulent Karoo in South Africa will aridi-fy. This region includes the range of the smallest tortoise, Homopus signatus signatus. Although the effects of rainfall on the physiology and ecology of H. s. signatus received attention in recent years, the results of these studies have not been integrated...
Many terrestrial chelonians are parasitized by ticks, but we have a poor understanding of what determines tick infestations on chelonian hosts. We counted ticks on Homopus signatus signatus during each spring in the years 2001–2004, and evaluated tick frequencies in relation to tortoise anatomy, climate and microhabitat. Tortoises hosted Ornithodor...
