Data from: Hunting behavior and feeding ecology of Mojave Rattlesnakes (Crotalus scutulatus), Prairie Rattlesnakes (C. viridis), and their hybrids in southwestern New Mexico
Data files
Nov 06, 2023 version files 33.36 MB
-
hunting_behavior.csv
-
hunting_frequency.csv
-
prey_encounter.csv
-
README.md
-
Scut.Vir.Hybrid.RADseq.WGS.205.QC.missing.corrected.filtered.snps.g.vcf.gz
-
small_mammal_trapping.csv
-
snake_SMI.csv
-
toad_lizard_P_A.csv
Abstract
Predators must contend with numerous challenges to successfully find and subjugate prey. Complex traits related to hunting are partially controlled by a large number of co-evolved genes which may be disrupted in hybrids. Accordingly, research on the feeding ecology of animals in hybrid zones has shown that hybrids sometimes exhibit transgressive or novel behaviors, yet for many taxa empirical studies of predation and diet across hybrid zones is lacking. We undertook the first such field study for a hybrid zone between two snake species, the Mojave Rattlesnake (Crotalus scutulatus) and Prairie Rattlesnake (C. viridis). Specifically, we leveraged established field methods to quantify hunting behaviors of animals, their prey communities, and diet of individuals across the hybrid zone in southwestern New Mexico, USA. We found that, even though hybrids had significantly lower body condition indices than snakes from either parental lineage, hybrids were generally similar to non-hybrids in hunting behavior, prey encounter rates, and predatory attack and success. We also found that, compared to C. scutulatus, C. viridis was significantly more active while hunting at night and abandoned ambush sites earlier in the morning, and hybrids tended to be more viridis-like in this respect. Prey availability was similar across the study sites, including within the hybrid zone, with Kangaroo Rats (Dipodomys spp.) as the most common small mammal both in habitat surveys and frequency of encounters with hunting rattlesnakes. Analysis of prey remains in stomachs and feces also showed broad similarity in diets, with all snakes preying primarily on small mammals and secondarily on lizards. Taken together, our results suggest that the significantly lower body condition of hybrids does not appear to be driven by differences in their hunting behavior or diet, and may instead relate to metabolic efficiency or other physiological traits we have not yet identified.
README: Hunting behavior and feeding ecology of Mojave Rattlesnakes (Crotalus scutulatus), Prairie Rattlesnakes (C. viridis), and their hybrids in southwestern New Mexico
This dataset includes final VCF alignment file used for hybrid index analysis, Scaled Mass Index (SMI), hunting behavior, hunting frequency, prey encounter types and rates, toad and lizard presence/absence, and small mammal trapping data used in order to quantify the hunting behaviors and diet of snakes dispersed across a hybrid zone between Mojave (Crotalus scutulatus) and Prairie (C. viridis) Rattlesnakes. The VCF alignment data were collected via raw sequence reads from DNA extractions from blood stored in lysis buffer. SMI was calculated from mass and snout*vent length measurements performed on the snakes. The hunting behavior and frequency, and prey encounters were collected via a combination of field telemetry and videography. Toad and lizard presence/absence data were collected via visual encounter surveys. Small mammal trapping data was collected via Sherman trapping lines. Generally, even though hybrids were in poorer body condition than snakes from either parental lineage, all snakes displayed similar hunting behaviors, and rates of predatory success.
Description of the data and file structure
VCF alignment: This file contains the biallelic variants for all individuals used in the behavioral analyses.
For all data:
- NA = data was not collected due to the data being not applicable (ex., NA for strike success since the snake never struck at a prey item, NAs in the small_mammal_trapping data when the trap did not capture a small mammal, or NA for HI_viridis_proportion due to sample failure)
snake_SMI:
- snake = the ID of the individual
- HI_scutulatus_proportion = 1 minus the HI_viridis_proportion
- HI_viridis_proportion = Hybrid index based on the VCF alignment
- genetic_species = which lineage the individual belonged to based on its hybrid index and the 0.05 and 0.95 cutoffs for parental groupings.
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
- SMI = Scaled Mass Index calculated based on Peig and Green 2009.
hunting_behavior:
- ID = the ID of the individual
- n = the number of hunting nights the snake was filmed for
- species = the putative grouping that the snake was assigned to based on site of capture and morphology
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
- sex = sex of the snake
- f = female
- m = male
- mass = mass of the snake to the nearest gram
- SVL = Snout Vent Length of the snake to the nearest millimeter
- SMI = Scaled Mass Index calculated based on Peig and Green 2009
- probe_freq = number of probes per minute of hunting
- night_probe_freq = number of probes per minute of hunting at night
- day_probe_freq = number of probes per minute of hunting after sunrise
- gape_freq = number of gapes per minute of hunting
- night_gape_freq = number of gapes per minute of hunting at night
- day_gape_freq = number of gapes per minute of hunting during the day
- prey_freq = number of encountered prey per minute by the snake while hunting
- strike_freq = number of strikes the snake elicited towards encountered prey per total prey encounters
- succ_freq = number of strikes that contacted the prey item per number of strikes the snake elicited towards encountered prey
- aftr_rise = number of minutes the snake spent hunting prior to sunrise
- before_down = number of minutes the snake spent hunting prior to sunset
- ave_abandontime = The average time of day in seconds that the snake stopped hunting
- trans_gape_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of gape_freq in order to perform a beta regressiontrans_day_probe_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of probe_freq in order to perform a beta regression
- trans_night_gape_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of night_gape_freq in order to perform a beta regression
- trans_day_gape_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of day_gape_freq in order to perform a beta regression
- trans_prey_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of prey_freq in order to perform a beta regression
- trans_strike_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of strike_freq in order to perform a beta regression
- trans_succ_freq = Zero inflated transformation (Smithson and Verkuilen 2005) of succ_freq in order to perform a beta regression
- HI_scutulatus_proportion = 1 HI_viridis_proportion
- HI_viridis_proportion = Hybrid index based on the VCF alignment
- genetic_species = which lineage the individual belonged to based on its hybrid index and the 0.05 and 0.95 cutoffs for parental groupings.
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
hunting_frequency:
- ID = the ID of the individual
- nights_tracked = the number of nights that the snake was located via field telemetry
- nights_hunted = the number of nights that the snake was located via field telemetry and it was on the surface in an ambush posture or was found eating a food item
- hunt_freq = nights_hunted divided by nights_tracked
- species = the putative grouping that the snake was assigned to based on site of capture and morphology
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
- sex = sex of the snake
- f = female
- m = male
- mass = mass of the snake to the nearest gram
- SVL = Snout Vent Length of the snake to the nearest millimeter
- SMI = Scaled Mass Index calculated based on Peig and Green 2009
- HI_scutulatus_proportion = 1 HI_viridis_proportion
- HI_viridis_proportion = Hybrid index based on the VCF alignment
- genetic_species = which lineage the individual belonged to based on its hybrid index and the 0.05 and 0.95 cutoffs for parental groupings.
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
prey_encounter:
- snake = the ID of the individual
- n = the number of hunting nights the snake was filmed for
- sex = sex of the snake
- f = female
- m = male
- mass = mass of the snake to the nearest gram
- SVL = Snout Vent Length of the snake to the nearest millimeter
- SMI = Scaled Mass Index calculated based on Peig and Green 2009
- genetic_species = which lineage the individual belonged to based on its hybrid index and the 0.05 and 0.95 cutoffs for parental groupings.
- CRSC = Crotalus scutulatus
- SCVI = Hybrid
- CRVI = Crotalus viridis
- Tambushtime.all = time in minutes that the snake spent hunting
- encounters = the number of prey encounters that the snake had while hunting
- prey.type = the type of prey that encountered the snake while it was hunting
- anuran = A frog or a toad
- bird = A non predatory bird (i.e., not a raptor or roadrunner)
- Dipodomys = A small mammal that belongs to the genus Dipodomys
- lizard = a lizard (squamata)
- non_Dipodomys = a small mammal that does not belong to the genus Dipodomys
- freqs = encounters divided by Tambushtime.all
toad_lizard_P_A
- site = the general location that the toad or lizard species was found in
- CRSC = Mojave Site (Southwest of Zone)
- SCVI = Hybrid Zone
- CRVI = Prairie Site (Northeast of Zone)
- year = the year the sites were sampled for the presence/absence of toad and lizard species
- dom_veg = a sub class of the site, breaking it up by the dominant vegetation type
- ANCO through UTST = the species code for each species found at least at one of the sites
- ANCO = Anaxyrus cognatus
- ANDE = Anaxyrus debilis
- ANPU = Anaxyrus punctatus
- ANWO = Anaxyrus woodhouseii
- SCCO = Scaphiopus couchii
- SPMU = Spea multiplicate
- ASspp = Aspidoscelis spp.
- COVA = Coleonyx variegatus
- GAWI = Gambelia wislizenii
- HOEL = Holbrookia elegans
- PHCO = Phrynosoma cornutum
- PHMO = Phrynosoma modestum
- SCspp = Sceloporus spp.
- UTST = Uta stansburiana
small_mammal_trapping
- year = the year that the small mammal trapping occurred
- population = the general location that the trap line was placed in
- CRSC = Mojave Site (Southwest of Zone)
- SCVI = Hybrid Zone
- CRVI = Prairie Site (Northeast of Zone)
- habitat = a sub class of the population, breaking it up by the dominant vegetation type
- trap line = the trap line for that specific population and habitat’s line
- trap number = the number of the trap in the trap line
- easting = the easting of the pair of traps place in the trap line (zone 12)
- northing = the northing of the pair of traps place in the trap line (zone 12)
- moon phase = the percentage of the moons surface that is visible that trap night, positive number indicate a waxing moon, negative numbers indicate a waning moon
- trap night = the date (mm/dd/yyyy) of the night that the traps were set on
- time open = the time of day (hh:mm) that the trap line was set
- midnight = midnight (00:00) used a reference point
- time close = the time of day (hh:mm) that the trap line was closed
- successful = was the trap successful in trapping a small mammal between the time open and time close
- species = the four character code (first two letters of the genus and first two letters of the species names) of the species of small mammal caught in the trap
- ID = the species code followed by the number of the ear tag used to tag the animal
- recap = was this individual recaptured before?
- sex = sex of the snake
- f = female
- m = male
- j = juvenile
- mass = the mass of the individual to the nearest 0.1 g
- SVL = Snout-Vent Length of the small mammal to the nearest millimeter
- tail length = Tail Length of the small mammal to the nearest millimeter
- hindfoot length = Hindfoot Length of the small mammal to the nearest millimeter
- hindfoot count = the number of digits on the right hindfoot of the small mammal
- condition = outward appearance of the small mammal
- ear clip/tag = the number of the ear tag that was used to tag the individual
- trap unavailable = was the trap rendered unavailable for whatever reason (covered in hundreds of ants, smashed by a cow, etc.)
Sharing/Access information
For additional ways to access this data and inquires about it, feel free to contact the corresponding author of the paper, Dr. Dylan Maag
Software
The VCF alignment data file can be accessed by software such as vcftools or bcftools.