Trophic specialization drives morphological evolution in sea snakes

Sherratt, Emma; Rasmussen, Arne Redsted; Sanders, Kate L.

doi:10.1098/rsos.172141

Cited by 43 publications

(58 citation statements)

References 38 publications

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“…Instead, speciation rates may be promoted by greater range sizes in Hydrophis that enhance species' persistence and provide opportunities for divergence across major biogeographic and ecological boundaries. Our previous studies of Hydrophis have shown strong vicariance at inter-regional scales [12], and rapid morphological evolution driven by ecological specialization [20]. However, work is needed to identify links among geographical, ecological and life-history traits in sea snake species formation and diversity limits.…”

Section: Discussionmentioning

confidence: 99%

Rates of population differentiation and speciation are decoupled in sea snakes

Hourston¹,

Udyawer

Sanders

2018

Biol. Lett.

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Comparative phylogeography can inform many macroevolutionary questions, such as whether species diversification is limited by rates of geographical population differentiation. We examined the link between population genetic structure and species diversification in the fully aquatic sea snakes (Hydrophiinae) by comparing mitochondrial phylogeography across northern Australia in 16 species from two closely related clades that show contrasting diversification dynamics. Contrary to expectations from theory and several empirical studies, our results show that, at the geographical scale studied here, rates of population differentiation and speciation are not positively linked in sea snakes. The eight species sampled from the rapidly speciating Hydrophis clade have weak population differentiation that lacks geographical structure. By contrast, all eight sampled Aipysurus -Emydocephalus species show clear geographical patterns and many deep intraspecific splits, but have threefold slower speciation rates. Alternative factors, such as ecological specialization, species duration and geographical range size, may underlie rapid speciation in sea snakes.

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Section: Discussionmentioning

confidence: 99%

Rates of population differentiation and speciation are decoupled in sea snakes

Hourston¹,

Udyawer

Sanders

2018

Biol. Lett.

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“…The only previously studied species, Aipysurus laevis , is indicated by a red asterisk. Tree modified from Sherratt et al (); legend is in millions of years ago (MYA); image of Aipysurus tenuis shows regions that were tested for phototactic responses, taken with permission from Mirtschin, Rasmussen, and Weinstein () [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Resultsmentioning

confidence: 99%

“…The only previously studied species, Aipysurus laevis, is indicated by a red asterisk. Tree modified from Sherratt et al (2018); legend is in millions of years ago (MYA); image of Aipysurus tenuis shows regions that were tested for phototactic responses, taken with permission from Mirtschin, Rasmussen, and Weinstein (2017) in our study to have phototactic tails. All sea snakes have paddle-shaped tails used for locomotion, and all species are active foragers that rest at times during the day, often under coral or rocky overhangs (Rasmussen, Murphy, Ompi, Gibbons, & Uetz, 2011).…”

Section: Discussionmentioning

confidence: 99%

Phototactic tails: Evolution and molecular basis of a novel sensory trait in sea snakes

et al. 2019

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Dermal phototaxis has been reported in a few aquatic vertebrate lineages spanning fish, amphibians and reptiles. These taxa respond to light on the skin of their elongate hind‐bodies and tails by withdrawing under cover to avoid detection by predators. Here, we investigated tail phototaxis in sea snakes (Hydrophiinae), the only reptiles reported to exhibit this sensory behaviour. We conducted behavioural tests in 17 wild‐caught sea snakes of eight species by illuminating the dorsal surface of the tail and midbody skin using cold white, violet, blue, green and red light. Our results confirmed phototactic tail withdrawal in the previously studied Aipysurus laevis, revealed this trait for the first time in A. duboisii and A. tenuis, and suggested that tail photoreceptors have peak spectral sensitivities between blue and green light (457–514 nm). Based on these results, and an absence of photoresponses in five Aipysurus and Hydrophis species, we tentatively infer that tail phototaxis evolved in the ancestor of a clade of six Aipysurus species (comprising 10% of all sea snakes). Quantifying tail damage, we found that the probability of sustaining tail injuries was not influenced by tail phototactic ability in snakes. Gene profiling showed that transcriptomes of both tail skin and body skin lacked visual opsins but contained melanopsin (opn4x) in addition to key genes of the retinal regeneration and phototransduction cascades. This work suggests that a nonvisual photoreceptor (e.g., Gq rhabdomeric) signalling pathway underlies tail phototaxis, and provides candidate gene targets for future studies of this unusual sensory innovation in reptiles.

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“…As snakes are vulnerable to both predator attack and injuries by their prey during prey manipulation and intraoral prey transport, they must reduce the time spent swallowing their prey. Previous studies have demonstrated a link between dietary preference and head shape in snakes (Camilleri & Shine, 1990; Fabre, Bickford, Segall, & Herrel, 2016; Forsman, 1991, 1996; Klaczko, Sherratt, & Setz, 2016; Queral-Regil & King, 1998; Sherratt, Rasmussen, & Sanders, 2018; Vincent, Moon, Herrel, & Kley, 2007). Although most of these studies used taxonomic groups to characterize snake diets (e.g.…”

Section: Introductionmentioning

confidence: 99%

Exploring the functional meaning of head shape disparity in aquatic snakes

Segall

Cornette

Godoy-Diana

et al. 2020

Preprint

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19Phenotypic diversity, or disparity, can be explained by simple genetic drift or, if functional 20 constraints are strong, by selection for ecologically relevant phenotypes. We here studied 21 phenotypic disparity in head shape in aquatic snakes. We investigated whether conflicting 22 selective pressures related to different functions have driven shape diversity and explore 23 whether similar phenotypes may give rise to the same functional output (i.e. many-to-one 24 mapping of form to function). We focused on the head shape of aquatically foraging snakes as 25 they fulfil several fitness-relevant functions and show a large amount of morphological 26 variability. We used 3D surface scanning and 3D geometric-morphometrics to compare the 27 head shape of 62 species in a phylogenetic context. We first tested whether diet specialization 28 and size are drivers of head shape diversification. Next, we tested for many-to-one mapping by 29 comparing the hydrodynamic efficiency of head shapes characteristic of the main axis of 30 variation in the dataset. We 3D printed these shapes and measured the forces at play during a 31 frontal strike. Our results show that diet and size explain only a small amount of shape variation. 32Shapes did not functionally converge as more specialized aquatic species evolved a more 33 efficient head shape than others. The shape disparity observed could thus reflect a process of 34 niche specialization under a stabilizing selective regime. 35

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Trophic specialization drives morphological evolution in sea snakes

Cited by 43 publications

References 38 publications

Rates of population differentiation and speciation are decoupled in sea snakes

Rates of population differentiation and speciation are decoupled in sea snakes

Phototactic tails: Evolution and molecular basis of a novel sensory trait in sea snakes

Exploring the functional meaning of head shape disparity in aquatic snakes

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