Data from: Biogeography of shell morphology in over-exploited shellfish reveals adaptive tradeoffs on human-inhabited islands and incipient selectively driven lineage bifurcation

Living and presumably healthy Cellana exarata were collected from eight Hawaiian Islands between 2012 and 2016: ‘Ōnū (ON, Gardner Pinnacles, Puha honu), Lalo (LA, La Perouse Pinnacles, Mokupāpapa), Mokumanamana (MM, Necker), Nihoa (NI), Kaua‘i (KA), O‘ahu (OA), Maui (MA), and Hawai‘i (HI, Big Island; Table 1; Kikiloi et al., 2017). The NWHI were accessed during intertidal monitoring cruises sponsored by Papahānaumokuākea Marine National Monument, and eight ‘opihi were collected from each of six, 1 cm size classes. In the MHI, shells of legal harvesting size (> 3 cm) were haphazardly collected along a 7 km section of coastline on Maui, two locations on Kaua‘i (Miloli‘i and Kekaha) and O‘ahu (Kaka‘ako, ‘Ᾱina Moana), and one location on each of the remaining islands. All sites were composed of natural basalt formations with the exceptions of the O‘ahu and Hawai‘i sites (basalt riprap) and Kekaha (emergent coral reef). Site selection was largely haphazard because shell morphology (at the level investigated here) was observed to be more homogenous within than between the NWHI and MHI. Images were taken of the lateral face of each individual with other measurements and measurements from images in csv files which are processed and analyzed using R code found https://github.com/jdselwyn/Opihi_Morphology.