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Intercontinental test of constraint-breaking adaptations; testing behavioural plasticity in the face of a predator with novel hunting strategies

Citation

Bleicher, Sonny; Kotler, Burt; Downs, Cynthia; Brown, Joel S (2020), Intercontinental test of constraint-breaking adaptations; testing behavioural plasticity in the face of a predator with novel hunting strategies, Dryad, Dataset, https://doi.org/10.5061/dryad.m905qftxp

Abstract

1. Constraint-breaking adaptations are evolutionary tools that provide a mechanism for incumbent-replacement between species filling similar ecological roles. 2. In common-garden experiments, we exposed populations of two desert rodents to two different viper species, testing their ability to adjust to novel predators that use different hunting strategies. We aimed to understand whether both predators and prey with constraint-breaking adaptations actually manifest comparative advantage over their counterparts. 3. We used convergent species from desert dunes in the Mojave Desert in North America, Merriam’s kangaroo rat (Dipodomys merriami) and the sidewinder rattlesnake (Crotalus cerastes), and from the Negev Desert in the Middle East, the greater Egyptian gerbil (Gerbillus pyramidum) and the Saharan horned vipers (Cerastes cerastes). Both Mojave species hold constraint-breaking adaptations in relation to their counterparts from the Negev. The rattlesnakes have heat sensing organs (pits) and the kangaroo rats have fur-lined cheek pouches that allow for greater foraging efficiency and food preservation. Using patch-use, we assessed the rodents’ risk-assessment from each snake— separately, together and in combination with barn owls. 4. Initially each rodent species foraged less in the presence of its familiar snake, but within a month both foraged less in the presence of the pit-viper (sidewinder). 5. Our findings indicate a level of learning, and behavioural plasticity, in both rodents and ability to assess the risk from novel predators. The kangaroo rats were capable of harvesting far greater amounts of resources under the same conditions of elevate risk. However, the reason for their advantage may lay in bi-pedal agility and not only their ability collect food more efficiently.

Methods

The dataset is measuring giving up densities (GUDs) for two months of each rodent population with variations in predation risk (owls, snakes), microhabitat hetergeneity, and varitation in ambient moonlight (moonphase). The data was cleaned by averaging all replications of treatments per night, resulting in 8 datapoints per night.  

Funding

United States - Israel Binational Science Foundation, Award: 2008/163