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349 results for “tortoises”
Data from: Genetic variation and population structure in the endangered Hermann's tortoise: the roles of geography and human-mediated processes
The Hermanni's tortoise (Testudo hermanni) is an endangered land tortoise distributed in disjoint populations across Mediterranean Europe. We investigated its genetic variation by typing one mitochondrial locus and nine nuclear microsatellites in approximately 300 individuals from 22 localities. Our goal was to understand the relative impact of natural and human-mediated processes in shaping the genetic structure, and to identify the genetic priorities for the conservation of this species. We found that i) all geographic areas are highly differentiated, mainly as a function of their distance but with a clear genetic discontinuity (Fst values larger than 0.4) between the Eastern and the Western subspecies; ii) the contact zone between subspecies is located farthest to the west than previously believed, and it probably coincides with the delta of the largest Italian river; iii) extinction events due to climatic conditions in the Upper Palaeolithic and subsequent human-mediated translocations in the Neolithic possibly explain the unexpected similarity among Spain, Sicily and Corsica. For conservation purposes, the large majority of genetic pools appears autochthonous, although hybridization among subspecies, related to extensive 20th century trade of tortoises across Europe, is observed in Spain and some Italian samples. Most populations do not seem at immediate risk of low genetic variation, except the French population, which has very low nuclear genetic diversity (heterozygosity = 0.25) and where 50 out of 51 sampled animals shared the same mitochondrial sequence. In general, restocking and reintroduction plans should carefully consider the genetic background of the individuals.
Data from: Close kin mating, but not inbred parents, reduces hatching rates and offspring quality in a threatened tortoise
Inbreeding depression, the reduction of fitness due to mating of related individuals, is of particular conservation concern in species with small, isolated populations. Although inbreeding depression is widespread in natural populations, long-lived species may be buffered from its effects during population declines due to long generation times, and thus are less likely to have evolved mechanisms of inbreeding avoidance than species with shorter generation times. However, empirical evidence of the consequences of inbreeding in threatened, long-lived species is limited. In this study, we leverage a well-studied population of gopher tortoises, Gopherus polyphemus, to examine the role of inbreeding depression and the potential for behavioral inbreeding avoidance in a natural population of a long-lived species. We tested the hypothesis that increased parental inbreeding leads to reduced hatching rates and offspring quality. Additionally, we tested for evidence of inbreeding avoidance. We found that high parental relatedness results in offspring with lower quality, and that high parental relatedness is correlated with reduced hatching success. However, we found that hatching success and offspring quality increase with maternal inbreeding, likely due to highly inbred females mating with more distantly-related males. We did not find evidence for inbreeding avoidance in males and outbred females, suggesting sex-specific evolutionary tradeoffs may have driven the evolution of mating behavior. Our results demonstrate inbreeding depression in a long-lived species and that the evolution of inbreeding avoidance is shaped by multiple selective forces.
Data from: Genetic rediscovery of an 'extinct' Galápagos giant tortoise species
Genes from recently extinct species can live on in the genomes of extant individuals of mixed ancestry. Recently, Poulakakis et al. detected genetic signatures of the giant Galápagos tortoise once endemic to Floreana Island (Chelonoidis elephantopus) within eleven hybrid individuals of otherwise pure C. becki on Volcano Wolf, Isabela Island. Movement of tortoises among islands by pirate and whaling ships was not uncommon during the 1800's, representing a likely mechanism by which individuals from Floreana were translocated to northern Isabela, despite being presumed extinct soon after Charles Darwin's historic voyage to the Galápagos Islands in 1835. These eleven hybrid individuals with C. elephantopus ancestry were thought to be the last genetic vestiges of a unique evolutionary lineage in the wild. Here we report that reproductively mature purebred tortoises of the recently 'extinct' C. elephantopus from Floreana Island are very likely still alive today, as identified and tracked through the genetic footprints' left in the genomes of very recent hybrid offspring on Volcano Wolf, Isabela Island. If found, these purebred C. elephantopus individuals could constitute core founders of a captive breeding program directed towards resurrecting this species.
Data from: Genetic variation and population structure in the endangered Hermann's tortoise: the roles of geography and human-mediated processes
The Hermanni's tortoise (Testudo hermanni) is an endangered land tortoise distributed in disjoint populations across Mediterranean Europe. We investigated its genetic variation by typing one mitochondrial locus and nine nuclear microsatellites in approximately 300 individuals from 22 localities. Our goal was to understand the relative impact of natural and human-mediated processes in shaping the genetic structure, and to identify the genetic priorities for the conservation of this species. We found that i) all geographic areas are highly differentiated, mainly as a function of their distance but with a clear genetic discontinuity (Fst values larger than 0.4) between the Eastern and the Western subspecies; ii) the contact zone between subspecies is located farthest to the west than previously believed, and it probably coincides with the delta of the largest Italian river; iii) extinction events due to climatic conditions in the Upper Palaeolithic and subsequent human-mediated translocations in the Neolithic possibly explain the unexpected similarity among Spain, Sicily and Corsica. For conservation purposes, the large majority of genetic pools appears autochthonous, although hybridization among subspecies, related to extensive 20th century trade of tortoises across Europe, is observed in Spain and some Italian samples. Most populations do not seem at immediate risk of low genetic variation, except the French population, which has very low nuclear genetic diversity (heterozygosity = 0.25) and where 50 out of 51 sampled animals shared the same mitochondrial sequence. In general, restocking and reintroduction plans should carefully consider the genetic background of the individuals.
Data from: Patterns of activity and body temperature of Aldabra giant tortoises in relation to environmental temperature
We studied the temperature relations of wild and zoo Aldabra giant tortoises (Aldabrachelys gigantea) focusing on: 1) the relationship between environmental temperature and tortoise activity patterns (n=8 wild individuals), and 2) on tortoise body temperature fluctuations, including how their core and external body temperatures vary in relation to different environmental temperature ranges (seasons; n=4 wild, and n=5 zoo individuals). In addition, we surveyed the literature to review the effect of body mass on core body temperature range in relation to environmental temperature in the Testudinidae. Diurnal activity of tortoises was bimodally distributed, and influenced by environmental temperature and season. The mean air temperature at which activity is maximised was 27.9˚C, with a range of 25.8–31.7˚C. Furthermore, air temperature predicted changes in the core body temperature better than did mass, and only during the coldest trial did tortoises with higher mass show more stable temperatures. Our results, together with the overall Testudinidae overview, suggest that, once variation in environmental temperature has been taken into account, there is little effect of mass on the temperature stability of tortoises. Moreover, the presence of thermal inertia in an individual tortoise depends on the environmental temperatures, and we found no evidence for inertial homeothermy. Finally, patterns of core and external body temperatures in comparison to environmental temperatures suggest that Aldabra giant tortoises act as mixed conformer-regulators. Our study provides a baseline to manage the thermal environment of wild and rewilded populations of an important island ecosystem engineer species in an era of climate change.
Data from: Genome-wide assessment of diversity and divergence among extant Galápagos giant tortoise species
Genome-wide assessments allow for fuller characterization of genetic diversity, finer-scale population delineation, and better detection of demographically significant units to guide conservation compared to those based on "traditional" markers. Galapagos giant tortoises (Chelonoidis spp.) have long provided a case study for how evolutionary genetics may be applied to advance species conservation. Ongoing efforts to bolster tortoise populations, which have declined by 90%, have been informed by analyses of mitochondrial DNA sequence and microsatellite genotypic data, but could benefit from genome-wide markers. Taking this next step, we used double-digest restriction-site associated DNA sequencing to collect genotypic data at >26,000 single nucleotide polymorphisms (SNPs) for 117 individuals representing all recognized extant Galapagos giant tortoise species. We then quantified genetic diversity, population structure, and compared results to estimates from mitochondrial DNA and microsatellite loci. Our analyses detected 12 genetic lineages concordant with the 11 named species as well as previously described structure within one species, C. becki. Furthermore, the SNPs provided increased resolution, detecting admixture in four individuals. SNP-based estimates of diversity and differentiation were significantly correlated with those derived from nuclear microsatellite loci and mitochondrial DNA sequences. The SNP toolkit presented here will serve as a resource for advancing efforts to understand tortoise evolution, species radiations, and aid conservation of the Galapagos tortoise species complex.
Data from: Population genomics through time provides insights into the consequences of decline and rapid demographic recovery through head-starting in a Galapagos giant tortoise
Population genetic theory related to the consequences of rapid population decline is well-developed, but there are very few empirical studies where sampling was conducted before and after a known bottleneck event. Such knowledge is of particular importance for species restoration, given links between genetic diversity and the probability of long-term persistence. To directly evaluate the relationship between current genetic diversity and past demographic events, we collected genome-wide single nucleotide polymorphism data from pre-bottleneck historical (c.1906) and post-bottleneck contemporary (c.2014) samples of Pinzón giant tortoises (Chelonoidis duncanensis; n=25 and 149 individuals, respectively) endemic to a single island in the Galapagos. Pinzón giant tortoises had a historically large population size that was reduced to just 150-200 individuals in the mid 20th century. Since then, Pinzón's tortoise population has recovered through an ex situ head-start program in which eggs or pre-emergent individuals were collected from natural nests on the island, reared ex situ in captivity until they were 4-5 years old, and subsequently repatriated. We found that the extent and distribution of genetic variation in the historical and contemporary samples was very similar, with the latter group not exhibiting the characteristic genetic patterns of recent population decline. No population structure was detected either spatially or temporally. We estimated an effective population size (Ne) of 58 (95% CI = 50-69) for the post-bottleneck population; no pre-bottleneck Ne point estimate was attainable (95% CI = 39-infinity) likely due to the sample size being lower than the true Ne. Overall, the historical sample provided a valuable benchmark for evaluating the head-start captive breeding program, revealing high retention of genetic variation and no skew in representation despite the documented bottleneck event. Moreover, this work demonstrates the effectiveness of head-starting in rescuing the Pinzón giant tortoise from almost certain extinction.
Figure 3 in The tortoise caterpillar: carnivory and armoured larval morphology of the metalmark butterfly Pachythone xanthe (Lepidoptera: Riodinidae)
Figure 3. Scanning electron microscopy of the last instar of Pachythone xanthe. (a,b) Prothoracic plate in external (a) and internal (b) views; (c) head capsule in lateral view.
Figure 2 in The tortoise caterpillar: carnivory and armoured larval morphology of the metalmark butterfly Pachythone xanthe (Lepidoptera: Riodinidae)
Figure 2. Scanning electron microscopy of the penultimate instar of Pachythone xanthe. (a) Lateral view, arrow pointing the tentacle nectary organ (TNOs) openings; (b) semi-open prothoracic plates in frontal view showing the head; (c) head and thorax in lateroventral view; (d) prothoracic spiracle; (e) detail of head in frontal view; (f) cluster of perforated cupola organs (PCOs), glandular openings and arborescent setae on the prothorax; (g) detail of dorsal cluster of cone-like setae on the A3 abdominal segment; (h) detail of lateral fringe setae; (i) A4 abdominal spiracle; (j) TNO in lateral view, note opening surrounded by PCOs; (k) detail of specialised setae on TNO.
Figure 1 in The tortoise caterpillar: carnivory and armoured larval morphology of the metalmark butterfly Pachythone xanthe (Lepidoptera: Riodinidae)
Figure 1. Natural history of Pachythone xanthe and symbiotic interactions with Azteca cf. chartifex ants and scale insects on a Miconia sp. tree. (a,b), penultimate instar in lateral (a) and dorsal (b) views, note the tentacle nectary organs (TNOs) openings (arrows); (c–f) last instar preying on ant-tended scale insects (yellow arrow) (c), resting posture (d), and frontal views showing the prothoracic plates closed (e) and open revealing the head (f); (g,h) pupa in lateral (g) and dorsal (h) views; (i) freshly emerged adult.
FIGURE 41 in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURE 41. Distribution of Eurypedus nigrosignatus (N) and Eurypedus peltoides (P); N? indicates 16 specimens of Eurypedus nigrosignatus from Museum of Comparative Zoology.
FIGURES 35–38. Male genitalia. 35 in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURES 35–38. Male genitalia. 35. Aedeagus of Eurypedus peltoides (ventral view). 36. Aedeagus of Eurypedus peltoides (lateral view). 37. Aedeagus of Eurypedus nigrosignatus (ventral view). 38. Aedeagus of Eurypedus nigrosignatus (lateral view). 39–40. Female genitalia. 39. Spermatheca of Eurypedus peltoides. 40. Spermatheca of Eurypedus nigrosignatus.
FIGURES 6–8. Eurypedus peltoides. 6. Dorsal view. 7. Lateral view. 8. Ventral view. 9–10. Eurypedus nigrosignatus. 9. Dorsal view. 10. Lateral view. 11. Ventral view. 12A–E in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURES 6–8. Eurypedus peltoides. 6. Dorsal view. 7. Lateral view. 8. Ventral view. 9–10. Eurypedus nigrosignatus. 9. Dorsal view. 10. Lateral view. 11. Ventral view. 12A–E. Dorsal color and morphological variation of Eurypedus peltoides.
FIGURES 13–15 in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURES 13–15. Head of Eurypedus peltoides. 13. Dorsal view. 14. Anterior view. 15. Ventral view (mouth fossa). 16–19. Mouthparts of Eurypedus peltoides. 16. Labrum. 17. Mandible. 18. Maxilla. 19. Labium. 20–23. Stridulatory files of Eurypedus nigrosignatus 20. Male (head dorsal view). 21. Stridulatory file (male). 22. Faint stridulatory file (female). 23. Female (head dorsal view). 24–27. Antenna of Eurypedus nigrosignatus. 24. Antenna (ventral view). 25. Antennomeres IV–VI. 26. Antennomere XI. 27. Ventral notch (antennomere VI).
FIGURES 29–30 in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURES 29–30. Prothorax in ventral views. 29. Eurypedus peltoides. 30. Eurypedus nigrosignatus. 31–34. Eurypedus nigrosignatus. 31. Mesonotum. 32. Complex of mesoventrite and metaventrite. 33. Metanotum. 34. Elytron (ventral view).
FIGURES 1–5. Type specimens. 1 in A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae)
FIGURES 1–5. Type specimens. 1. Holotype of Cassida oblonga Sturm in Thon (= Eurypedus thoni). 2. Lectotype of Eurypedus peltoides. 3. Lectotype of Ischyrosonyx nigrosignata (= Eurypedus nigrosignatus). 4. Lectotype of Ischyrosonyx discipennis (= Eurypedus discipennis). 5. Lectotype of Ischyrosonyx marginicollis (= Eurypedus marginicollis).
Fig 5 in Description of a New Galapagos Giant Tortoise Species (Chelonoidis; Testudines: Testudinidae) from Cerro Fatal on Santa Cruz Island
Fig 5. Frequency distribution of genetic distances between different Galapagos giant tortoise species (A: microsatellite DNA, B: mitochondrial DNA). For each histogram, a dark gray column indicates where the observed genetic distance between the Cerro Fatal and Reserva tortoises falls. Left: Microsatellite genetic distances calculated from purebred individuals in the reference measured using FST (top) or RST (below). Right: DNA sequence genetic distances based on mtDNA haplotypes from purebred individuals in the reference database, measured using uncorrected p-distances (top), or maximum likelihood (ML)-corrected distances (below).
Fig 2 in Description of a New Galapagos Giant Tortoise Species (Chelonoidis; Testudines: Testudinidae) from Cerro Fatal on Santa Cruz Island
Fig 2. (A) Bayesian Inference (BI) tree reconstructed from the dataset including all unique mtDNA control region haplotypes previously sampled from extant and extinct species as well as the three museum specimens of giant Galapagos tortoises analyzed in this study. Numbers on branches indicate posterior probabilities. Only the nodal support values for the major lineages are presented. Red and green colors identify museum samples analyzed in the present and previous studies, respectively. (B) Haplotype network showing matrilineal diversity recovered from 70 sequences of C. porteri from Reserva, 51 sequences of the lineage from Cerro Fatal, and 2 sequences of C. chathamensis from San Cristóbal Island. Twenty-five inferred mutations separate the haplogroups of Chelonoidis sp. nov. from Cerro Fatal from the ones from C. porteri from Reserva.
Fig 1 in Description of a New Galapagos Giant Tortoise Species (Chelonoidis; Testudines: Testudinidae) from Cerro Fatal on Santa Cruz Island
Fig 1. Geographic distribution of the two known lineages of giant tortoises on Santa Cruz Island: Chelonoidis porteri (Reserva) and Chelonoidis sp. nov. (Cerro Fatal) (indicated in dark gray). Light gray area connecting the distribution areas of the two species indicates agricultural land. Modified from Russello et al. [11].
Fig 6. A-E in Description of a New Galapagos Giant Tortoise Species (Chelonoidis; Testudines: Testudinidae) from Cerro Fatal on Santa Cruz Island
Fig 6. A-E. The skull of the museum specimen UWZS 32700, holotype for Chelonoidis sp. nov. from Cerro Fatal in Santa Cruz (A: dorsal, B: ventral, C: occipital, D: frontal and E: lateral view).
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