Biology subjects

Sanderson, M. J.

Publications and source records attributed to Sanderson, M. J..

3 recordsLinked to original sources

bioRxiv2023

An improved genome assembly of the saguaro cactus (Carnegiea gigantea (Engelm.) Britton & Rose).

We present an improved genome assembly of the saguaro cactus (Carnegiea gigantea (Engelm.) Britton & Rose), obtained by incorporating long-read PacBio data to the existing short reads. The assembly improves in terms of total size, contiguity, and accuracy, allowing to extend the range of sequence analyses beyond the single-gene scale. Consequently, the assembly is 16% larger and has 20% more genes, expanding the resources for a neglected yet very remarkable plant family such as Cactaceae. Species taxonomyEukaryota; Viridiplantae; Streptophyta; Streptophytina; Embryophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliopsida; Mesangiospermae; eudicotyledons; Gunneridae; Pentapetalae; Caryophyllales; Cactineae; Cactaceae; Cactoideae; Echinocereeae; Carnegiea gigantea (Engelm.) Britton & Rose) (also known as saguaro cactus) (NCBI txid: 171969).

genomics↗

bioRxiv2022

Chromosome-length genome assemblies of cactophilic Drosophila illuminate links between structural and sequence evolution.

A thorough understanding of adaptation and speciation requires model organisms with both a history of ecological and phenotypic study as well as a robust set of genomic resources. For decades, the cactophilic Drosophila species of the southwestern US and northern Mexico have fit this profile, serving as a crucial model system for understanding ecological adaptation, particularly in xeric environments, as well as the evolution of reproductive incompatibilities and speciation. Here, we take a major step towards gaining a complete molecular description of this system by assembling and annotating seven chromosome-length de novo genomes across the three species D. mojavensis, D. arizonae, and D. navojoa. Using this data, we present the most accurate reconstruction of the phylogenetic history of this clade to date. We further demonstrate a relationship between structural evolution and coding evolution both within and between species in this clade, and use this relationship to generate novel hypotheses for adaptation genes. All of our data are presented in a new public database (cactusflybase.arizona.edu), providing one of the most in-depth resources for the analysis of inter- and intraspecific evolutionary genomic data.

genomics↗

bioRxiv2021

Accuracy in near-perfect virus phylogenies

AO_SCPLOWBSTRACTC_SCPLOWPhylogenetic trees from real-world data often include short edges with very few substitutions per site, which can lead to partially resolved trees and poor accuracy. Theory indicates that the number of sites needed to accurately reconstruct a fully resolved tree grows at a rate proportional to the inverse square of the length of the shortest edge. However, when inferred trees are partially resolved due to short edges, "accuracy" should be defined as the rate of discovering false splits (clades on a rooted tree) relative to the actual number found. Thus, accuracy can be high even if short edges are common. Specifically, in a "near-perfect" parameter space in which trees are large, the tree length{xi} (the sum of all edge lengths), is small, and rate variation is minimal, the expected false positive rate is less than{xi} /3; the exact value depends on tree shape and sequence length. This expected false positive rate is far below the false negative rate for small{xi} and often well below 5% even when some assumptions are relaxed. We show this result analytically for maximum parsimony and explore its extension to maximum likelihood using theory and simulations. For hypothesis testing, we show that measures of split "support" that rely on bootstrap resampling consistently imply weaker support than that implied by the false positive rates in near-perfect trees. The near-perfect parameter space closely fits several empirical studies of human virus diversification during outbreaks and epidemics, including Ebolavirus, Zika virus, and SARS-CoV-2, reflecting low substitution rates relative to high transmission/sampling rates in these viruses.

evolutionary biology↗