This experiment is part of the Arachnids Challenge Grant. Browse more projects

Are male daddy-longlegs becoming "endangered?"

San Diego State University
San Diego, California
BiologyEcology
DOI: 10.18258/7844
Grant: Arachnids
$3,001
Raised of $3,000 Goal
100%
Funded on 11/04/16
Successfully Funded
  • $3,001
    pledged
  • 100%
    funded
  • Funded
    on 11/04/16

Methods

Summary

Collection: I will collect specimens in the Wichita Mountains and Tishomingo Wildlife Refuges of Oklahoma, and the Ouachita Mountains and Ozarks National Forests in Arkansas. While collecting I will estimate sex ratio based on male density per patch/tree trunk, and take GPS coordinates of patches/trees. 

Sequencing: I will use ddRAD sequencing to sample the genomes of Leiobunum relictum, L. vittatum, and L. crassipalpe I am able to collect. 

Phylogenetic Analysis: Genetic variants identified within and between species will be use to build gene and species trees. I will employ the program BEAST to evaluate divergence time between L. relictum and sister taxa.

Morphology: The reproductive organs (pedipalps, penis, pre-genital chambers) of all individuals will be examined. I will measure pedipalpal length and thickness, female pre-genital chamber sclerotization (size of cuticular pads that occlude the opening of the genital tract) and attachment area of the female opercular muscle. The traits will be analyzed in a discriminant function analysis to evaluate whether species-specific variance in traits overlaps between L. relictum and its sister taxa. 

Evaluating Modes of Parthenogenesis: I have three hypotheses for the reason behind apparent female bias in collections of L. relictum. 1) Collections just happened to pick up more females than males due to time of year/ the fact females are often bigger than males. 2) They are infected with Wolbachia, which can selectively kill males and enable females to reproduce asexually, laying lots of female eggs. 3) They are able to reproduce asexually by some other reason. I will maintain alive few females I collect in Oklahoma, storing them in individual terraria and collecting any eggs that they lay. Eggs will be maintained in petri dishes until fully mature, then females and eggs will be preserved.  I hope use targeted enrichment to potentially identify Wolbachia in females and to employ technology I am currently developing to genotype eggs and assess whether they were produced sexually or asexually.

Protocols

This project has not yet shared any protocols.