scholarly journals Head-started Agassiz’s desert tortoises Gopherus agassizii achieved high survival, growth, and body condition in natural field enclosures

2020 ◽  
Vol 43 ◽  
pp. 305-321
Author(s):  
KA Nagy ◽  
BT Henen ◽  
LS Hillard
Keyword(s):  
Body Condition ◽  
Mojave Desert ◽  
Early Summer ◽  
High Survival ◽  
Gopherus Agassizii ◽  
Free Living ◽  
Age Cohort ◽  
Control Food ◽  
Condition Indices ◽  
Water Supplementation

We measured survival, growth, and body condition of 8 hatchling cohorts of desert tortoises Gopherus agassizii (living in predator-resistant outdoor pens in the Mojave Desert, California, USA) over 11 yr to evaluate head-starting methods. At 11 yr of age, 7 times as many of the first cohort had survived than if they had been free-living tortoises. Subsequent improvements in predator control, food and water supplementation, and pen structure increased survival from 7 to 10 times that under wild conditions in younger cohorts. Annual survival averaged 96%. Carapace length (CL) increased 6.95 mm yr-1, similar to that of free-living tortoises. Annual growth rates varied with calendar year (possibly reflecting food and water supply), age, cohort (year hatched), mother, and in 4 dry years, with crowding. Most of the first cohort grew to a releasable size (CL >100 mm) by their 9th year. Body condition indices remained high, indicating little dehydration despite droughts in 8 of the 11 years, because irrigation offered drinking opportunities. Head-started tortoises developed fully hardened shells (≥98% of adult shell hardness) earlier (10.1 vs. 11.6 yr), but at a larger CL (117 vs. 104 mm) than did free-living tortoises. Selective feeding in head-start pens decreased subsequent germination of favored wildflower species, apparently by reducing the natural seedbank. Consequently, we reseeded and irrigated each autumn to promote subsequent spring food supply. We irrigated in early summer to enable drinking and ensuing consumption of dry, dead plants and Bermuda grass hay, a supplement. These procedures can greatly improve juvenile survivorship, and increase numbers of hard-shelled, midsized juveniles to help augment wild populations.

Impact of extrafloral nectar availability and plant genotype on ant (Hymenoptera: Formicidae) visitation to quaking aspen (Salicaceae)

2015 ◽  
Vol 148 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Jonathon R. Newman ◽  
Diane Wagner ◽  
Patricia Doak
Keyword(s):  
Populus Tremuloides ◽  
Late Summer ◽  
Early Summer ◽  
Quaking Aspen ◽  
Plant Genotype ◽  
Free Living ◽  
Natural Induction ◽  
Formica Fusca ◽  
Time Of Year ◽  
Nectar Availability

AbstractFor quaking aspen (Populus tremuloides Michaux; Salicaceae) the rate of extrafloral (EF) sugar secretion is increased by defoliation and decreased by drought. Although wholesale blocking of EF nectar has been shown to reduce ant (Hymenoptera: Formicidae) visitation to aspen, the effect of more subtle and realistic variations in nectar availability on ant recruitment is unknown. Working in Alaskan boreal forest (United States of America), we reduced and supplemented EF nectar availability on potted aspen ramets of three genotypes and surveyed visitation by free-living Formica fusca (Linnaeus) (Hymenoptera: Formicidae). Ants were more responsive to a subtle increase in sugar availability than to a decrease. While nectar reduction had no effect on ant visitation, nectar supplementation increased ant visitation to one aspen genotype by 70% during an early summer trial. Average ant visitation to different aspen genotypes varied during the late summer, indicating that aspen genotype can influence attractiveness to ants. We conclude that natural induction of EF secretion in response to herbivory may benefit aspen through improved ant recruitment, though the response is dependent on aspen genotype and time of year. Differences among aspen genets in attractiveness to ants could influence the relative success of genotypes, especially in settings in which aspen regenerates from seed.

Seasonal Reproductive Cycle of the Desert Tortoise (Gopherus agassizii) in the Eastern Mojave Desert

1994 ◽  
Vol 8 ◽  
pp. 72 ◽  
Author(s):  
David C. Rostal ◽  
Valentine A. Lance ◽  
Janice S. Grumbles ◽  
Allison C. Alberts
Keyword(s):  
Reproductive Cycle ◽  
Mojave Desert ◽  
Gopherus Agassizii ◽  
Desert Tortoise

scholarly journals Improved draft of the Mojave Desert tortoise genome, Gopherus agassizii, version 1.1

2017 ◽  
Author(s):  
Timothy H Webster ◽  
Greer A. Dolby ◽  
Melissa Wilson Sayres ◽  
Kenro Kusumi
Keyword(s):  
Threatened Species ◽  
Mojave Desert ◽  
Gene Annotation ◽  
Draft Genome ◽  
Gopherus Agassizii ◽  
Desert Tortoise ◽  
Draft Genome Assembly ◽  
Initial Release ◽  
Exogenous Sequence ◽  
Mojave Desert Tortoise

Exogenous sequence contamination presents a challenge in first-draft genomes because it can lead to non-contiguous, chimeric assembled sequences. This can mislead downstream analyses reliant on synteny, such as linkage-based analyses. Recently, the Mojave Desert Tortoise (Gopherus agassizii) draft genome was published as a resource to advance conservation efforts for the threatened species and discover more about chelonian biology and evolution. Here, we illustrate steps taken to improve the desert tortoise draft genome by removing contaminating sequences—actions that are typically carried out after the initial release of a draft genome assembly. We used information from NCBI’s Vecscreen output to remove intra-scaffold contamination and trim heading and trailing Ns. We then reordered and renamed scaffolds, and transferred the gene annotation onto this assembly. Finally, we describe the tools developed for this pipeline, freely available on Github (https://github.com/thw17/G_agassizii_reference_update), which facilitate post-assembly processing of other draft genomes. The new gopAga1.1 genome has an N50 of 251 KB, L50 of 2592 scaffolds, and its annotation retains 17,201 of the original 20,172 genes that were unaffected by the scaffold processing.

scholarly journals Improved draft of the Mojave Desert tortoise genome, Gopherus agassizii, version 1.1

2018 ◽  
Author(s):  
Timothy H Webster ◽  
Greer A Dolby ◽  
Melissa A Wilson Sayres ◽  
Kenro Kusumi
Keyword(s):  
Threatened Species ◽  
Mojave Desert ◽  
Gene Annotation ◽  
Draft Genome ◽  
Gopherus Agassizii ◽  
Desert Tortoise ◽  
Draft Genome Assembly ◽  
Initial Release ◽  
Exogenous Sequence ◽  
Mojave Desert Tortoise

Exogenous sequence contamination presents a challenge in first-draft genomes because it can lead to non-contiguous, chimeric assembled sequences. This can mislead downstream analyses reliant on synteny, such as linkage-based analyses. Recently, the Mojave Desert Tortoise (Gopherus agassizii) draft genome was published as a resource to advance conservation efforts for the threatened species and discover more about chelonian biology and evolution. Here, we illustrate steps taken to improve the desert tortoise draft genome by removing contaminating sequences—actions that are typically carried out after the initial release of a draft genome assembly. We used information from NCBI’s Vecscreen output to remove intra-scaffold contamination and trim heading and trailing Ns. We then reordered and renamed scaffolds, and transferred the gene annotation onto this assembly. Finally, we describe the tools developed for this pipeline, freely available on Github (https://github.com/thw17/G_agassizii_reference_update), which facilitate post-assembly processing of other draft genomes. The new gopAga1.1 genome has an N50 of 251 kb, L50 of 2592 scaffolds, and its annotation retains 17,201 of the original 20,172 genes that were unaffected by the scaffold processing.

Comparing three body condition indices in amphibians: a case study of yellow-bellied toad Bombina variegata

2010 ◽  
Vol 31 (4) ◽  
pp. 558-562 ◽  
Author(s):  
Rodica Plăiaşu ◽  
Tibor Hartel ◽  
Raluca Ioana Băncilă ◽  
Dan Cogălniceanu ◽  
Joost Smets
Keyword(s):  
Body Size ◽  
Body Condition ◽  
Condition Index ◽  
Quality Parameters ◽  
Direct Measurements ◽  
Wide Range ◽  
Bombina Variegata ◽  
Condition Indices ◽  
Three Body

AbstractBody condition is important because it is correlated with population and habitat quality parameters. Since the direct measurements are either lethal or unreliable, a wide range of non-lethal body condition indices has been proposed. The aim of our study was to apply and compare three body condition indices (Fulton's index, relative body condition mass index and residual index) using body size indicator – body mass data for 24 populations of the yellow bellied toad (Bombina variegata). The condition index should be independent of body size indicator, in this case snout vent length (SVL). Therefore we tested all three indices for the statistical independence of SVL and for the normality of distribution. Fulton's index violated the independence assumption, whereas the relative body condition mass index did not have a normal distribution. Residual index was found both independent of SVL and normally distributed. Moreover, the residual index highlighted biological significant differences on the basis of altitude and season. Our results recommend the residual index as a useful tool in amphibian monitoring and conservation.

scholarly journals Immune and sex-biased gene expression in the threatened Mojave desert tortoise, Gopherus agassizii

PLoS ONE ◽  
2020 ◽  
Vol 15 (8) ◽  
pp. e0238202
Author(s):  
Cindy Xu ◽  
Greer A. Dolby ◽  
K. Kristina Drake ◽  
Todd C. Esque ◽  
Kenro Kusumi
Keyword(s):  
Gene Expression ◽  
Mojave Desert ◽  
Gopherus Agassizii ◽  
Desert Tortoise ◽  
Mojave Desert Tortoise

STELLER SEA LION BODY CONDITION INDICES

2000 ◽  
Vol 16 (2) ◽  
pp. 427-436 ◽  
Author(s):  
K. W. Pitcher ◽  
D. G. Calkins ◽  
G. W. Pendleton
Keyword(s):  
Body Condition ◽  
Steller Sea Lion ◽  
Sea Lion ◽  
Condition Indices

scholarly journals Mojave desert tortoise (Gopherus agassizii) thermal ecology and reproductive success along a rainfall cline

2015 ◽  
Vol 10 (3) ◽  
pp. 282-294 ◽  
Author(s):  
Annette E. SIEG ◽  
Megan M. GAMBONE ◽  
Bryan P. WALLACE ◽  
Susana CLUSELLA-TRULLAS ◽  
James R. SPOTILA ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Mojave Desert ◽  
Thermal Ecology ◽  
Gopherus Agassizii ◽  
Desert Tortoise ◽  
Mojave Desert Tortoise
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