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Fig. 2 in A new lineage of Galapagos giant tortoises identified from museum samples

Fig. 2 Statistical parsimony haplotype network of the mitochondrial control region (668 bp) for 129 contemporary individuals from San Cristóbal and six historical specimens collected in 1906, as well as 28 representative haplotypes from the other species of Galapagos giant tortoise. The name of the island where each species occurs is labeled with capital letters, with current taxonomy in italics. Haplotypes are represented as black circles on the network, the size of the circle is proportional to the frequency of the haplotype in the analysis. Open circles represent unsampled, hypothesized haplotypes, and hash marks indicate a single mutational change. Reticulations reflect uncertainty in relationships, or homoplasy.

Fig. 4 Barplots depicting K in A new lineage of Galapagos giant tortoises identified from museum samples

Fig. 4 Barplots depicting K = 2 for the STRUCTURE analysis using the SNP (12 192 loci) and microsatellite (21 loci) genotypes for the contemporary San Cristóbal population (n = 64). Each bar represents an individual and the proportion of the bar that is each color represents the membership of that individual to the two clusters. The order of individuals is the same in both plots, black boxes around bars highlight individuals with a greater than 0.4 discrepancy in assignment proportions between the analyses.

Fig. 3 in A new lineage of Galapagos giant tortoises identified from museum samples

Fig. 3 Bayesian Inference maximum clade credibility cladogram showing relationships among the San Cristóbal historical samples from the cave and collected alive in 1906, and a reference dataset of 93 Galapagos giant tortoise haplotypes and three outgroups based on the mitochondrial control region (alignment length 718 bp), estimated using BEAST with a strict clock and Birth Death tree. The numbers on the branches are the posterior probability support values. § indicates the C. chathamensis type specimen. The name of the island where each clade is found is in capitals, with current taxonomy in italics.

Fig. 1 in A new lineage of Galapagos giant tortoises identified from museum samples

Fig. 1 Map of the Galapagos Archipelago, indicating the locations of each Chelonoidis species, with San Cristóbal Island enlarged in the inset map. Island names are in capital letters. The approximate location of the cave where the bones were found in 1906 is marked, as is the approximate location where CAS 8133 was collected alive and the region of Punta Pitt.

Figure 10A-E in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 10A-E. Identified costals in external and visceral views. A. UCMP 136526. B. UCMP 134831. C. UCMP 137148. D. UCMP 95918. E. UCMP 95919. Scale bars=4 cm.

Figure 7. A in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 7. A. Ventral view of articulated right and partial left hypoplastron, UCMP 136527. B. Locations of sutures and of sulci between abdominal, femoral, and inguinal scales, UCMP 136527. C. Ventral view of posterior plastron including most of left and right hypoplastron and xiphiplastron, UCMP 134830. D. Locations of sutures and sulci between abdominal and femoral scales, UCMP 134830. Scale bars=4 cm.

Figure 3 in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 3. Stratigraphy of the Mehrten Formation and adjacent formations. Modified from Wagner (1981).

Figure 4 in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 4. Photograph of island tortoise site (UCMP V71137). Arrow points to stratigraphic position of the site.

Figure 1A-G in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 1A-G. Map of published Hesperotestudo localities in Califor- nia. A. Ingram Creek, Miocene (Clarendonian), San Pablo Forma- tion (Brattstrom 1961). B. Turlock Lake, late Miocene-early Pliocene (Hemphillian), Mehrten Formation (Casteel and Hutchison 1973, Wagner 1981). C. Monocline Ridge, middle Miocene (Barstovian), Temblor Formation (Tseng and Stewart 2009) D. Kettleman Hills, upper Pliocene-Pleistocene, Tulare Formation (Boessenecker and Poust 2015). E. Hungry Valley, Hemphillian, lower Hungry Valley Formation (Miller and Downs 1974). F. Gypsum Ridge, unnamed formation, late Blancan-early Irvingtonian (Wagner and Prothero 2001). G. Vallecito Creek–Fish Creek, Pliocene-Pleistocene, Hueso and Tapiado Formations (Jefferson 2001, Murray 2008).

Figure 8A-D. Two xiphiplastra. A in A fossil giant tortoise from the Mehrten Formation of Northern California

Figure 8A-D. Two xiphiplastra. A. Dorsal view of UCMP 132086, a left Figure 9A-C. Peripherals. A. Right peripheral 5, lateral view, UCMP xiphiplastra. B. Ventral view of UCMP 132086 showing sulcus between 97986. B. Pygal, left and right peripheral pairs 10-11, and left periphfemoral and anal scales. C. Ventral view of UCMP 132084, right xiphi- eral 9, posterior view showing sulci separating marginal scales, UCMP plastron showing sulci. D. Dorsal view of UCMP 132084. Scale bars=4 95919. C. Lateral view, two articulated partial left peripherals, UCMP cm 95918. Scale bars=4 cm.

opencc-zeroAug 2022View details →

Microsatellite genotypes for temporal monitoring of the Floreana Island Galapagos Giant Tortoise captive breeding program

Captive breeding programs benefit from genetic analyses that identify relatedness between individuals, assign parentage to offspring, and track levels of genetic diversity. Monitoring these parameters across breeding cycles is critical to the success of a captive breeding program as it allows conservation managers to iteratively evaluate and adjust program structure. However, in practice, genetic tracking of breeding outcomes is rarely conducted. Here, we examined the first three offspring cohorts (2017 – 2020) of the genetically-informed captive breeding program for the Floreana Island Galapagos giant tortoise, Chelonoidis niger. This captive breeding program is unique as the Floreana tortoise has been extinct since the 1800s, but its genome persists, in part, in the form of living hybrids with the extant Volcano Wolf tortoise, Chelonoidis becki. Breeding over the study period took place at the Galapagos National Park Directorate breeding facility in four corrals, each containing three females and two males. Using 17 microsatellite markers, we were able to assign parentage to 94 of the 98 offspring produced over the study period. We observe that despite the addition of more founders since the pilot breeding program, the effective population size remains low, and changes to the arrangements of breeding corrals may be necessary to encourage more equal reproductive output from the males. This study demonstrates the value of hybrids for species restoration and the importance of continually reassessing the outcomes of captive breeding.

opencc-zeroFeb 2023View details →

Navigating agricultural landscapes: Responses of critically endangered giant tortoises to farmland vegetation and infrastructure

Context: Interactions between wildlife and anthropogenic infrastructure, such as roads, fences, and dams, can influence wildlife movement, and potentially cause human-wildlife conflict. In the Galapagos archipelago, two species of critically endangered giant tortoise encounter infrastructure and human-modified vegetation in farms, which could influence movement choices. Objectives: We investigated factors influencing tortoise movement and habitat selection in the agricultural landscape of Santa Cruz Island, Galapagos. Methods: We examined the movement of 27 tortoises collected using GPS tracking between 2014 and 2020, in relation to the location of vegetation, ponds, fences, and roads. Results: We found that tortoises preferred pasture over native vegetation, but there was little difference among their preferences for native vegetation, crops, or invasive vegetation. Tortoises also travelled slower in pasture, and faster in invasive vegetation, compared to crops and native vegetation. Tortoises were more likely to be found closer to ponds than predicted by chance. Our results indicated that most fences were porous to tortoises, with limited impact on their movement. Tortoises were more likely to use areas near roads with low-traffic. Conclusions: Pastures and ponds are important habitats for tortoises in farms and are likely to be used preferentially by tortoises. Overall, fences and roads did not strongly obstruct tortoise movements, however, this may lead to potential injury to tortoises on roads and property damage for farmers. To best identify priority areas for managing wildlife on farms, we recommend evaluating the combined effects of multiple anthropogenic landscape features on wildlife movements.

opencc-zeroMay 2023View details →

Raw data from: Environmental variation structures reproduction and recruitment in long-lived mega-herbivores: Galapagos Giant Tortoises

Understanding drivers of vital rates is important for testing life history theory, predicting population dynamics, and guiding conservation. Migratory, long-lived animals are important to life history theory because they present an extreme among trade-offs in vital rates: delayed maturity, low fecundity, variable recruitment rates, and long generation times. Understanding how vital rates respond to environmental variation has been elusive for such species because of difficulties in studying wide-ranging animals over extended periods. Populations that live on elevation gradients can provide tractable study systems because considerable environmental change occurs over small geographic distances. Galapagos tortoises are an iconic example; they are long-lived, migrate seasonally, face multiple anthropogenic threats, and have cryptic early life history stages for which vital rates are unknown. From 2012–2021, we studied the reproductive ecology of two species of Galapagos tortoises along elevation gradients that coincided with substantial change in climate and vegetation productivity. Specifically, we 1) measured physical and reproductive condition of adult females, 2) tracked the movements of 33 adult females using GPS telemetry, and re-located them seasonally to measure condition, 3) recorded nest temperatures, clutch characteristics, and egg survival from 107 nests, and 4) used radio telemetry to re-locate 104 hatchlings to monitor growth, survival, and movements. We also monitored temperature, rainfall, and primary productivity from field and remotely sensed data along the elevation gradient. Adult females were either elevational migrants or year-round lowland residents. Migrants had higher body condition than residents, and body condition was positively correlated with fecundity. Nests occurred in the hottest, driest part of the tortoise's range, between 6–165m elevation. Clutch size increased with elevation, egg survival declined, and hatchling survival and growth were highest at intermediate elevations. Hatchlings dispersed rapidly between 100–750 m from their nests before becoming sedentary in ranges <0.05 ha. Environmental variability mediated by elevation influenced adult fecundity and juvenile recruitment. Predicted future climates will profoundly impact the relationships between elevation and vital rates of Galapagos tortoises and other species living on elevation gradients. Resilience will be maximized by ensuring connectivity of foraging and reproductive areas within current and possible future elevational ranges of these species.