Evaluating local adaptation of a complex phenotype: reciprocal tests of pigmy rattlesnake venoms on treefrog prey

Smiley-Walters, Sarah A.; Farrell, Terence M.; Gibbs, H. Lisle

doi:10.1007/s00442-017-3882-8

Cited by 19 publications

(17 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several selection-driven hypotheses have been proposed to explain the dichotomy between neurotoxic and hemorrhagic snake venom phenotypes because venom is expected to be locally adapted to prey at a very fine geographic scale 7 , 29 – 32 . These hypotheses have centered on potential differences in the digestive efficiency of the two venom types 33 ; Type B venoms likely provide more efficient digestion of prey at lower temperatures or when temperature fluctuations are pronounced 8 , 34 , although evidence for an increase in digestive efficiency in Type B venoms remains controversial (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (Crotalus scutulatus)

Strickland

Smith

Mason

et al. 2018

Sci Rep

View full text Add to dashboard Cite

Snake venoms represent an enriched system for investigating the evolutionary processes that lead to complex and dynamic trophic adaptations. It has long been hypothesized that natural selection may drive geographic variation in venom composition, yet previous studies have lacked the population genetic context to examine these patterns. We leverage range-wide sampling of Mojave Rattlesnakes (Crotalus scutulatus) and use a combination of venom, morphological, phylogenetic, population genetic, and environmental data to characterize the striking dichotomy of neurotoxic (Type A) and hemorrhagic (Type B) venoms throughout the range of this species. We find that three of the four previously identified major lineages within C. scutulatus possess a combination of Type A, Type B, and a ‘mixed’ Type A + B venom phenotypes, and that fixation of the two main venom phenotypes occurs on a more fine geographic scale than previously appreciated. We also find that Type A + B individuals occur in regions of inferred introgression, and that this mixed phenotype is comparatively rare. Our results support strong directional local selection leading to fixation of alternative venom phenotypes on a fine geographic scale, and are inconsistent with balancing selection to maintain both phenotypes within a single population. Our comparisons to biotic and abiotic factors further indicate that venom phenotype correlates with fang morphology and climatic variables. We hypothesize that links to fang morphology may be indicative of co-evolution of venom and other trophic adaptations, and that climatic variables may be linked to prey distributions and/or physiology, which in turn impose selection pressures on snake venoms.

show abstract

Section: Introductionmentioning

confidence: 99%

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (Crotalus scutulatus)

Strickland

Smith

Mason

et al. 2018

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Median lethal dose values (LD 50 ) within 24 h for each combination of venom and prey type were estimated from models using the dose.p function from the MASS package [64]. A 95% confidence interval for each LD 50 value was calculated using the formula for normal distribution [65].…”

Section: Discussionmentioning

confidence: 99%

High Specific Efficiency of Venom of Two Prey-Specialized Spiders

Michálek

Kuhn‐Nentwig

Pekár

2019

Toxins

View full text Add to dashboard Cite

The venom of predators should be under strong selection pressure because it is a costly substance and prey may potentially become resistant. Particularly in prey-specialized predators, venom should be selected for its high efficiency against the focal prey. Very effective venom paralysis has been observed in specialized predators, such as spiders preying on dangerous prey. Here, we compared the toxicity of the venoms of two prey-specialized species, araneophagous Palpimanus sp. and myrmecophagous Zodarion nitidum, and their related generalist species. We injected different venom concentrations into two prey types—the prey preferred by a specialist and an alternative prey—and observed the mortality and the paralysis of the prey within 24 h. We found that the venoms of specialists were far more potent towards the preferred prey than alternative prey. The venoms of generalists were similarly potent towards both prey types. In addition, we tested the efficacy of two venom fractions (smaller and larger than 10 kDa) in araneophagous Palpimanus sp. Compounds larger than 10 kDa paralyzed both prey types, but smaller compounds (<10 kDa) were effective only on preferred prey, suggesting the presence of prey-specific compounds in the latter fraction. Our results confirm that prey-specialized spiders possess highly specific venom that allows them to subdue dangerous prey.

show abstract

“…Further, this component of functional diversity may equal or outweigh functional differences in venom due to local adaptation that have dominated adaptive explanations for intraspecific variation in venom (e.g. [9,10]). royalsocietypublishing.org/journal/rsbl Biol.…”

Section: Discussionmentioning

confidence: 99%

High levels of functional divergence in toxicity towards prey among the venoms of individual pigmy rattlesnakes

2019

Self Cite

View full text Add to dashboard Cite

Venom is a complex molecular phenotype that shows high levels of variation in expressed proteins between individuals within and between populations. However, the functional significance of this variation in terms of toxicity towards prey is largely unknown. Here, we assessed the relative toxicity of venom from individual pygmy rattlesnakes ( Sistrurus miliarius ) on brown anoles ( Anolis sagrei ) using a novel assay involving tests of fixed doses of venom from individual snakes on individual lizards. We found high levels of functional variation between individual venoms within populations with individual differences (nested within population) explaining 3.6 times more variation in toxicity than population differences. Our results suggest a previously unappreciated adaptive significance to within-population variation in venom. They argue that selective mechanisms that maintain variation within populations may be of equal or greater importance to divergent selection leading to local adaption between populations as evolutionary explanations of venom variation within species.

show abstract

Evaluating local adaptation of a complex phenotype: reciprocal tests of pigmy rattlesnake venoms on treefrog prey

Cited by 19 publications

References 63 publications

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (Crotalus scutulatus)

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (Crotalus scutulatus)

High Specific Efficiency of Venom of Two Prey-Specialized Spiders

High levels of functional divergence in toxicity towards prey among the venoms of individual pigmy rattlesnakes

Contact Info

Product

Resources

About