• A near-chromosome-scale genome assembly of the gemsbok (Oryx gazella): an iconic antelope of the Kalahari desert

      Farré, Marta; Li, Qiye; Zhou, Yang; Damas, Joana; Chemnick, Leona G.; Kim, Jaebum; Ryder, Oliver A.; Ma, Jian; Zhang, Guojie; Larkin, Denis M.; et al. (2018)
      Background The gemsbok (Oryx gazella) is one of the largest antelopes in Africa. Gemsbok are heterothermic and thus highly adapted to live in the desert, changing their feeding behavior when faced with extreme drought and heat. A high-quality genome sequence of this species will assist efforts to elucidate these and other important traits of gemsbok and facilitate research on conservation efforts. Findings Using 180 Gbp of Illumina paired-end and mate-pair reads, a 2.9 Gbp assembly with scaffold N50 of 1.48 Mbp was generated using SOAPdenovo. Scaffolds were extended using Chicago library sequencing, which yielded an additional 114.7 Gbp of DNA sequence. The HiRise assembly using SOAPdenovo + Chicago library sequencing produced a scaffold N50 of 47 Mbp and a final genome size of 2.9 Gbp, representing 90.6% of the estimated genome size and including 93.2% of expected genes according to Benchmarking Universal Single-Copy Orthologs analysis. The Reference-Assisted Chromosome Assembly tool was used to generate a final set of 47 predicted chromosome fragments with N50 of 86.25 Mbp and containing 93.8% of expected genes. A total of 23,125 protein-coding genes and 1.14 Gbp of repetitive sequences were annotated using de novo and homology-based predictions. Conclusions Our results provide the first high-quality, chromosome-scale genome sequence assembly for gemsbok, which will be a valuable resource for studying adaptive evolution of this species and other ruminants.
    • Contemporary demographic reconstruction methods are robust to genome assembly quality: A case study in Tasmanian devils

      Patton, Austin H; Margres, Mark J; Stahlke, Amanda R; Hendricks, Sarah; Lewallen, Kevin; Hamede, Rodrigo K; Ruiz-Aravena, Manuel; Ryder, Oliver A.; McCallum, Hamish I; Jones, Menna E; et al. (2019)
      Reconstructing species’ demographic histories is a central focus of molecular ecology and evolution. Recently, an expanding suite of methods leveraging either the sequentially Markovian coalescent (SMC) or the site-frequency spectrum has been developed to reconstruct population size histories from genomic sequence data. However, few studies have investigated the robustness of these methods to genome assemblies of varying quality. In this study, we first present an improved genome assembly for the Tasmanian devil using the Chicago library method. Compared with the original reference genome, our new assembly reduces the number of scaffolds (from 35,975 to 10,010) and increases the scaffold N90 (from 0.101 to 2.164 Mb). Second, we assess the performance of four contemporary genomic methods for inferring population size history (PSMC, MSMC, SMC++, Stairway Plot), using the two devil genome assemblies as well as simulated, artificially fragmented genomes that approximate the hypothesized demographic history of Tasmanian devils. We demonstrate that each method is robust to assembly quality, producing similar estimates of Ne when simulated genomes were fragmented into up to 5,000 scaffolds. Overall, methods reliant on the SMC are most reliable between ?300 generations before present (gbp) and 100 kgbp, whereas methods exclusively reliant on the site-frequency spectrum are most reliable between the present and 30 gbp. Our results suggest that when used in concert, genomic methods for reconstructing species’ effective population size histories 1) can be applied to nonmodel organisms without highly contiguous reference genomes, and 2) are capable of detecting independently documented effects of historical geological events.
    • Hologenomic adaptations underlying the evolution of sanguivory in the common vampire bat

      Mendoza, M. Lisandra Zepeda; Xiong, Zijun; Escalera-Zamudio, Marina; Runge, Anne Kathrine; Thézé, Julien; Streicker, Daniel; Frank, Hannah K.; Loza-Rubio, Elizabeth; Liu, Shengmao; Ryder, Oliver A.; et al. (2018)
      The common vampire bat (Desmodus rotundus) is one of only three obligate blood-feeding mammals. By sequencing both its genome and gut metagenome, the authors provide a holistic view of the evolutionary adaptations that underlie this unusual diet.
    • Into the night: camera traps reveal nocturnal activity in a presumptive diurnal primate, (Rhinopithecus brelichi)

      Tan, Chia L.; Yang, Yeqin; Niu, Kefeng (2013)
      Most living primates exhibit a daytime or nighttime activity pattern. Strict diurnality is thought to be the rule among anthropoids except for owl monkeys. Here we report the diel activity pattern of an Asian colobine, the Guizhou snub-nosed monkey Rhinopithecus brelichi, based on a methodology that relied on using 24-h continuously operating camera traps. We conducted the study in Fanjingshan National Nature Reserve in Guizhou, China from March 22 to May 19 and from June 17 to October 14, 2011. After standardizing all time elements to a meridian-based time according to the geographic coordinates of the study site, we showed unequivocally that the monkeys, though predominantly diurnal, exhibited activity beyond daylight hours throughout the study. Specifically, their activity at night and during twilight periods suggests a complex interplay of behavioral adaptations, among others, to living in a temperate environment where day length and food resources fluctuate substantially across seasons. We contend that, under prevailing ecological conditions, so-called strictly diurnal primates may adjust their activity schedule opportunistically in order to increase energy intake. We also discuss the advantages of using camera traps in primate studies, and how the standardized use of meridian-based time by researchers would benefit comparisons of diel activity patterns among primates.
    • Phenotypic variability along a climatic gradient in a perennial afrotropical rainforest understorey herb

      Ley, Alexandra C.; Herzog, Patrick; Lachmuth, Susanne; Abwe, Abwe E.; Christian, Mbella F.; Sesink Clee, Paul R.; Abwe, Ekwoge E.; Morgan, Bethan J.; Gonder, Mary K. (2018)
      Plants evolved in response to climatic conditions, which shaped their geographic distribution, functional traits and genetic composition. In the face of climatic changes, plants have to react by either genetic adaptation, phenotypic plasticity or geographic range shift....
    • Physiological consequences of Arctic sea ice loss on large marine carnivores: Unique responses by polar bears and narwhals

      Pagano, Anthony M.; Williams, Terrie M. (2021)
      Rapid environmental changes in the Arctic are threatening the survival of marine species that rely on the predictable presence of the sea ice. Two Arctic marine mammal specialists, the polar bear (Ursus maritimus) and narwhal (Monodon monoceros), appear especially vulnerable to the speed and capriciousness of sea ice deterioration as a consequence of their unique hunting behaviors and diet, as well as their physiological adaptations for slow-aerobic exercise….