Big Spider, Big Genome: Chromosome-level genome of a North American tarantula (Aphonopelma marxi) and comparative genomics across 300 million years of spider evolution

Posted by
  Image Credit: WikiCommons Big Spider, Big Genome: Chromosome-level genome of a North American tarantula (Aphonopelma marxi) and comparative genomics across 300 million years of spider evolution Abstract The comparison of chromosome-level genomes allows biologists to investigate new axes of organismal evolution. Spiders comprise a significant proportion of known arachnid diversity, with many complex morphologies and unique natural histories, yet comparative genomics in spiders has been limited due to the number of available genomes. We present a de novo chromosomal reference genome of a mature male tarantula, Aphonopelma marxi, and comparatively examine spider genome evolution across the Order Araneae. Using PacBio HiFi and Hi-C sequencing, the final 6.5 Gb assembly consists of 17 autosomes, 1 X chromosome, and 127 unplaced scaffolds, with an N50 of 370 Mb and Arachnida (odb10; 2934 genes) BUSCO of 96.7%. By comparing 20 additional spider genomes from 15 families, we find mygalomo...

Females become adults about ten days earlier than males in a phalangiid harvestman Odiellus aspersus (Opiliones: Eupnoi: Phalangiidae)

Posted by

 


Females become adults about ten days earlier than males in a phalangiid harvestman Odiellus aspersus (Opiliones: Eupnoi: Phalangiidae)

Abstract

The reproductive phenology of a species of phalangiid harvestmen, Odiellus aspersus, was studied at Maruyama Park, Sapporo, Hokkaido, for the difference in adult emergence between males and females. At the timepoint in which 50% of the population had matured to adulthood, more females were represented than males, and adult females developed about 10 days earlier on average than males. There was no difference in adult body size between males that had matured earlier and males that were collected later in the season. This fact would conflict with a plausible hypothesis that males should mature slowly to attain larger body size in this species. Elongation of spermatheca in females of the species may explain the marked difference in the adult emergence in the species, by enhancing sperm priority of the males that copulated with females last.

Nobuo Tsurusaki "Females become adults about ten days earlier than males in a phalangiid harvestman Odiellus aspersus (Opiliones: Eupnoi: Phalangiidae)," The Journal of Arachnology, 53(1), 8-12, (19 May 2025) https://doi.org/10.1636/JoA-S-23-025