From darkness to twilight: Morphological divergence between cave and surface-subterranean ecotone Niphargus species
Data files
Aug 05, 2024 version files 73.09 KB
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Biroetal_Fromdarkness_Original_data.xlsx
72.01 KB
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README.md
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Abstract
Subterranean and surface habitats are in stark contrast in several environmental factors. Therefore, adaptation to the subterranean environment typically impedes the (re)colonisation of surface habitats. The genus Niphargus includes amphipod crustaceans that primarily occupy subterranean habitats. All its species show typical adaptations to the subterranean environment. However, some Niphargus species occur in surface-subterranean ecotones. To understand whether (i) habitat divergence is present between the cave and the ecotone species (ii) similar phenotypes emerge independently in every ecotone, we studied morphological divergence between four cave and four ecotone Niphargus species based on 13 functional morphological traits. To account for different selection acting on the sexes, we included males (N = 244) and females (N = 222). Nine out of 13 traits showed habitat- divergence. Traits related to feeding and crawling were shorter in ecotone species, while traits related to oxygenation were larger in ecotone species. Eleven out of 13 traits were sexually dimorphic. Traits related to oxygenation and crawling were larger in females, while the trait related to swimming was larger in males. We found that the extent of sexual dimorphism differs between the habitats in eight traits related to sensing, feeding, oxygenation and crawling. Additionally, we found that in certain traits related to sensing and oxygenation, habitat related differences are only present in case of one but not the other sex. We conclude that the detected differences between the cave and the ecotone species indicate divergent evolution, where similarities among the different species within a habitat type indicate convergent evolution. The high degree of sexual dimorphism paired with differences in sexual dimorphism between the habitats in certain traits suggest that sexual and fecundity selections have comparable effects to environmental selection. Thus, studies of habitat-dependent adaptations investigating one sex only, or not considering sexual dimorphism, can lead to erroneous conclusions. --
README: From darkness to twilight: Morphological divergence between cave and surface-subterranean ecotone Niphargus species
https://doi.org/10.5061/dryad.5x69p8dc0
The data contains morphological measurements of 13 traits plus the body length of eight species of the *Niphargus *genus. The traits were measured on microscope slides except for body length which was measured using photos. The dataset contains the R script used for analysis.
Description of the data and file structure
The original data file contains linear measurements of the given traits in millimeter. Species_abbreviation in the original data denote the following species:
POD - Niphargus podpecanus; SPO - Niphargus spoeckeri; SCO - Niphargus scopicauda; STY - Niphargus stygius; TIM - Niphargus timavi; SPH - Niphargus sphagnicolus; SPI - Niphargus spinulifemur; KRA - Niphargus krameri
Sharing/Access information
Code/Software
The R code used for the analysis is called Biroetal_Fromdarkness_code and is uploaded to Zenodo in the linked repository.