2019/11/19 by José Cerca, Christian Meyer, Dave Stateczny +6 · 48 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Environmental Science · #Aquatic Invertebrate Ecology and Behavior #Biology #Clade #Divergence (linguistics) #Ecology #Evolutionary biology #Gene #Genetic algorithm #Genetic diversity and population structure #Genetics #Marine Biology and Ecology Research #Morphological analysis #Morphology (biology) #Phylogenetic tree #Phylogenetics #Range (aeronautics) #Reproductive isolation #Species complex #Taxon #Zoology
paper · pdf · doi:10.1111/evo.13884
published in Evolution 74(1), 116-131 (Oxford University Press)
openalex publication_date 2019/11/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/26
Morphological stasis or the absence of morphological change is a well-known phenomenon in the paleontological record, yet it is poorly integrated with neontological evidence. Recent evidence suggests that cryptic species complexes may remain morphologically identical due to morphological stasis. Here, we describe a case of long-term stasis in the Stygocapitella cryptic species complex (Parergodrilidae, Orbiniida, Annelida). Using phylogenetic methods and morphological data, we find that rates of morphological evolution in Stygocapitella are significantly slower than in closely related taxa (Nerillidae, Orbiniidae). Assessment of quantitative and qualitative morphology revealed the presence of four morphotypes with only subtle differences, whereas molecular data supports 10 reproductively isolated clades. Notably, estimates for the time of Stygocapitella species divergence range from ∼275 million years to ∼18 million years, including one case of two morphologically similar species that have diverged about 140 million years ago. These findings provide evidence for morphological deceleration and long-term morphological stasis in Stygocapitella, and that speciation is not necessarily accompanied by morphological changes. The deceleration of morphological divergence in Stygocapitella can be potentially linked to niche conservatism and tracking, coupled with the fluctuating dynamics of the interstitial environment, or genetic constraints due to progenetic evolution. Finally, we conclude that failing to integrate speciation without morphological evolution in paleontology may bias estimates of rates of speciation and morphological evolution.