Comparative shape of two recently diverged species of Pacific Rockfish: Sebastes ciliatus and S. variabilis

Species delimitation can be based on consideration of several different criteria, including differentiation of ecological or functional traits. Two species of Pacific rockfish, the dark rockfish (Sebastes ciliatus) and the dusky rockfish (Sebastes variabilis), appear to represent recently divergent evolutionary lineages. We evaluate evidence for differentiation of these two species in somatic shape using geometric morphometrics in two locations in the northeast Pacific where they occur in sympatry. Somatic shape was significantly different between species, but species’ shape did not vary between the two locations. Sebastes ciliatus had an upturned, relatively smaller head, eye, and jaw, and an elongated mid-body; whereas, S. variabilis had a downturned, larger head, eye, and jaw, and a shorter mid-body. These results suggest that S. ciliatus and S. variabilis are morphometrically differentiated in a similar way in both locations. Somatic shape differentiation between these two sympatric..., For this study, we collected S. ciliatus and S. variabilis via hook and line fishing in Frederick Sound near the north end of Kuiu Island, Alaska in late June of 2016, and in Icy Strait, Alaska in June of 2023 (160 km straight line distance between the two sampling locations; Figure 1). We used samples of both species collected in both locations for comparison of divergence in somatic shape. We used a total of 105 specimens; 60 S. ciliatus, 34 from Kuiu (18 males, 16 females) and 26 from Icy Strait (15 males, 11 females); 45 S. variabilis, 17 from Kuiu (8 males, 9 females) and 28 from Icy Strait (12 males, 16 females). Both species are considered sexually monomorphic and we had a relatively even mix of both sexes in each sample. Specimens for both species ranged from 30 – 47 cm in both locations.
Specimens were photographed within a few minutes after capture to ensure that photos reflected fresh, relaxed, and natural shape variation. For each individual in all samples we photographed th..., , # Comparative shape of two recently diverged species of Pacific Rockfish: Sebastes ciliatus and S. variabilis

[https://doi.org/10.5061/dryad.v41ns1s5d](https://doi.org/10.5061/dryad.v41ns1s5d)

## Description of the data and file structure

For this study, we collected *S. ciliatus* and *S. variabilis* via hook and line fishing in Frederick Sound near the north end of Kuiu Island, Alaska in late June of 2016, and in Icy Strait, Alaska in June of 2023 (160 km straight line distance between the two sampling locations; Figure 1). We used samples of both species collected in both locations for comparison of divergence in somatic shape. We used a total of 105 specimens; 60 *S. ciliatus*, 34 from Kuiu (18 males, 16 females) and 26 from Icy Strait (15 males, 11 females); 45 *S. variabilis*, 17 from Kuiu (8 males, 9 females) and 28 from Icy Strait (12 males, 16 females). Both species are considered sexually monomorphic  and we had a relatively even mix of both sexes in each sample. Specimens f...