Multiple mechanisms contribute to isolation-by-environment in the redheaded pine sawfly, Neodiprion lecontei

Isolation by environment (IBE) is a population genomic pattern that arises when ecological barriers reduce gene flow between populations. Although current evidence suggests IBE is common in nature, few studies have evaluated the underlying mechanisms that generate IBE patterns. In this study, we evaluate five proposed mechanisms of IBE (natural selection against immigrants, sexual selection against immigrants, selection against hybrids, biased dispersal, environment-based phenological differences) that may give rise to host-associated differentiation within a sympatric population of the redheaded pine sawfly, Neodiprion lecontei, a species for which IBE has previously been detected. We first characterize the three pine species used by N. lecontei at the site, finding morphological and chemical differences among the hosts that could generate divergent selection on sawfly host-use traits. Next, using morphometrics and ddRAD sequencing, we detect modest phenotypic and genetic differentiati..., , , ## README for \"Multiple mechanisms contribute to isolation-by-environment in the redheaded pine sawfly, Neodiprion lecontei\"

## All scripts can be found on Zenodo, and all data files are on Dryad. The two repositories share the same folder structure. This file gives an overview of both the scripts and data.

# Host\_Phenotype\_IBE: This folder contains the scripts and data files used to perform the host plant characterization, morphological, and IBE analyses.

# Authors: Catherine R. Linnen, Robin K. Bagley, Christopher J. Frost

# The script folder contains the following file

# - Host\_Phenotype\_IBE\_Scripts.R: R script with commented segments for performing the following analyses (in order of appearance):

# - Analysis of host plant characteristics

# - Needle width

# - Volatile analysis

# - Resin content analysis

# - Analysis of ovipositor shape

# - Analysis of IBE mechanisms

# - Natural selection against immigrants

# - Egg-to-cocoon survival

# - Development time

# - Cocoo...