Patterns of morphological variation following colonization of a novel prey environment

Clifton, Ian T.; Chamberlain, Jeremy D.; Gifford, Matthew E.

doi:10.1111/jzo.12459

Cited by 6 publications

(5 citation statements)

References 35 publications

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“…Adult male body sizes, however, do not signi cantly differ among the populations. Across all populations, adult female body size is larger than adult males (Clifton et al 2017), likely stemming from the faster female juvenile growth rates we detected compared to males. Adult female watersnakes likely experience a "fecundity-advantage" with increasing body size (Shine 1988;Weatherhead et al 1995).…”

Section: Discussionmentioning

confidence: 76%

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Plastic juvenile growth rates and offspring size: A response to anthropogenic shifts in prey size among populations

Chamberlain,

Clifton,

Gifford

2023

Preprint

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Variation in prey characteristics among populations is frequently associated with similar variation in predator body sizes. Increasingly, human-mediated alterations in prey landscapes impose unique ecological pressures on predators that may lead to rapid shifts in predator body size. Here, we ask whether adult body size differences among populations are the product of genetic adaptation or phenotypic plasticity of juvenile growth in response to human-altered prey size differences. Using a common-garden design, we measured growth rates of neonate diamond-backed watersnakes (Nerodia rhombifer) from fish farms populations that vary substantially in prey size distributions. We also investigated the influence of initial offspring size differences on growth rate. We found that juvenile growth rates were faster for snakes from populations with access to larger average prey sizes. Our data suggest that these differences are the product of phenotypic plasticity, mediated through differences in initial size and prey consumption. Population-level differences in growth rate were not detected when initial size and prey mass consumed were included in the model. We propose that larger offspring sizes may favor increased growth rates, mediated through a larger energy processing capacity relative to smaller individuals. This experiment provides evidence supporting the growing body of literature that adaptive plasticity may be a significant driver of rapid phenotypic divergence among populations across a landscape. This mechanism may explain the stability and colonization of populations in the face of rapid, human-mediated, landscape changes.

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Section: Discussionmentioning

confidence: 76%

“…We have characterized body size differences of the watersnakes colonizing these sites. Female snakes from large-prey sites (KEO and JOHO) have an 8% larger maximal adult body length than their conspeci cs from the small-prey site (GNC) (Clifton et al 2017). Interestingly, adult male body sizes among these populations do not differ.…”

Section: Study Sitesmentioning

confidence: 99%

Plastic juvenile growth rates and offspring size: A response to anthropogenic shifts in prey size among populations

Chamberlain,

Clifton,

Gifford

2023

Preprint

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“…Such a system might clarify the mechanisms and time courses over which adaptive genetically based variation replaces plasticity as a source of fitness-relevant morphological variation among populations (e.g. [7,30]).…”

Section: Discussionmentioning

confidence: 99%

“…Snakes are highly plastic organisms [27][28][29][30], and their relatively simple morphology facilitates studies on adaptive phenotypic plasticity in skeletal traits [31]. In snakes, two main skeletal structures are known to respond to environmental conditions: the number of vertebrae and the dimensions of the trophic apparatus ( jaws).…”

Section: Introductionmentioning

confidence: 99%

“…Geographical variation in both body size and RJS are widespread in various snake lineages, within as well as among species [30,31,[36][37][38][39][40][41]. However, the respective influences of local (genetically based) adaptation versus plasticity have not been examined, because too few populations have been studied and/or because rates of genetic exchange among populations have not been known.…”

Section: Introductionmentioning

confidence: 99%

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Plasticity matches phenotype to local conditions despite genetic homogeneity across 13 snake populations

et al. 2021

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In a widespread species, a matching of phenotypic traits to local environmental optima is generally attributed to site-specific adaptation. However, the same matching can occur via adaptive plasticity, without requiring genetic differences among populations. Adult sea kraits ( Laticauda saintgironsi ) are highly philopatric to small islands, but the entire population within the Neo-Caledonian Lagoon is genetically homogeneous because females migrate to the mainland to lay their eggs at communal sites; recruits disperse before settling, mixing up alleles. Consequently, any matching between local environments (e.g. prey sizes) and snake phenotypes (e.g. body sizes and relative jaw sizes (RJSs)) must be achieved via phenotypic plasticity rather than spatial heterogeneity in gene frequencies. We sampled 13 snake colonies spread along an approximately 200 km northwest–southeast gradient ( n > 4500 individuals) to measure two morphological features that affect maximum ingestible prey size in gape-limited predators: body size and RJS. As proxies of habitat quality (HQ), we used protection status, fishing pressure and lagoon characteristics (lagoon width and distance of islands to the barrier reef). In both sexes, spatial variation in body sizes and RJSs was linked to HQ; albeit in different ways, consistent with sex-based divergences in foraging ecology. Strong spatial divergence in morphology among snake colonies, despite genetic homogeneity, supports the idea that phenotypic plasticity can facilitate speciation by creating multiple phenotypically distinct subpopulations shaped by their environment.

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How anatomy influences measurements of snakes

Cundall,

Deufel,

Pattishall

2024

Journal of Morphology

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Anatomy compromises the precision and accuracy of measurements made of the body length and head size of live snakes. Body measures (snout‐vent length, SVL) incorporate many synovial intervertebral joints, each allowing flexion and limited extension and compression. Radiographs of the trunk in 14 phylogenetically diverse species in resting and stretched conditions combined with dissections and histological analysis of intervertebral joints show that the synovial nature of these joints underlies the variance in SVL measures. Similarly, the ubiquity and variety of viscoelastic tissues connecting mobile snout and jaw elements of alethinophidian snakes underlie variances in length and width measures of the head. For the overall size of the head and jaw apparatus, the part that can be most easily and relatively precisely measured for many snakes is the mandible because it has only one mobile joint. As to accuracy, the anatomy of intervertebral and cranial joints supports the hypothesis that in living snakes, the head and trunk have no exact size.

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Patterns of morphological variation following colonization of a novel prey environment

Cited by 6 publications

References 35 publications

Plastic juvenile growth rates and offspring size: A response to anthropogenic shifts in prey size among populations

Plastic juvenile growth rates and offspring size: A response to anthropogenic shifts in prey size among populations

Plasticity matches phenotype to local conditions despite genetic homogeneity across 13 snake populations

How anatomy influences measurements of snakes

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