DOI: 10.5061/dryad.sd931
title: Data from: Parent-of-origin growth effects and the evolution of hybrid inviability in dwarf hamsters

description: Mammalian hybrids often show abnormal growth, indicating that
 developmental inviability may play an important role in mammalian
 speciation. Yet, it is unclear if this recurrent phenotype reflects a
 common genetic basis. Here, we describe extreme parent-of-origin-dependent
 growth in hybrids from crosses between two species of dwarf hamsters,
 Phodopus campbelli and Phodopus sungorus. One cross type resulted in
 massive placental and embryonic overgrowth, severe developmental defects,
 and maternal death. Embryos from the reciprocal cross were viable and
 normal sized, but adult hybrid males were relatively small. These effects
 are strikingly similar to patterns from several other mammalian hybrids.
 Using comparative sequence data from dwarf hamsters and several other
 hybridizing mammals, we argue that extreme hybrid growth can contribute to
 reproductive isolation during the early stages of species divergence.
 Next, we tested if abnormal growth in hybrid hamsters was associated with
 disrupted genomic imprinting. We found no association between imprinting
 status at several candidate genes and hybrid growth, though two
 interacting genes involved in embryonic growth did show reduced expression
 in overgrown hybrids. Collectively, our study indicates that
 growth-related hybrid inviability may play an important role in mammalian
 speciation but that the genetic underpinnings of these phenotypes remain
 unresolved.
description: Embryo_placenta_weightsThese data include the weights of all embryos and placentas as well as other birth defects. These data are in 15 columns: 1. ID: unique Identification number for each individual. In the form BB.BB1.1, the first two letters are the mother's species (BB=P. campbelli, SS=P. sungorus). The second two letters are the father's species. Thus hybrids are designated BB.SS or SS.BB. The first number is the unique litter number and the final number is the individual in that litter. 2. Cross: the unique cross identification number, or the cross each individual was from. 3. Date: date that the mother was sacrificed and the dissection was done. 4. Age: the approximate age that the embryos were in development. day 15-18 are considered "late development". 5. Reabsorbing: 0 if not reabsorbing, 1 if reabsorbing. 6. molar conceptus: 0 if not a molar conceptus, 1 if a molar conceptus. 7. edema: 0 if no edema, 1 if edema was present. 8. photo number: the photo name. 9. gender: sex if known. 10: Genes: a description of pure P. campbelli (BB.BB), pure P. sungorus (SS.SS) or the F1 P. campbelli x P. sungorus (BB.SS). 11: Embryo: embryo weight in grams. 12: Placenta: placenta weight in grams. 13: Individual: the individual in the litter. 14: Mother: mother's unique identification number. 15: Father: father's un ique identification number.Breeding_successThese data are the reproductive output of different crosses. These data are in 4 columns: 1. cross.number: in the form "BB.BB1" Letters represent species ( B=P. campbelli, S=P. sungorus ). The first two letters are the mother's species, the second two letters are the father's species. Further, each unique litter is given a number. 2. mother.number: the unique identification number of the mother. 3. days.to.birth: number of days from crossing to a successful birth. 4. success.preg: 1 if the female gave birth in the first 40 days, 0 if she did not give birth in the first 40 days10_day_weightsData for assessing standard growth curves of hamsters from day 10 to day 100. This file includes 5 columns: 1. cross.number: in the form "BB.BB1" Letters represent species ( B=P. campbelli, S=P. sungorus ). The first two letters are the mother's species, the second two letters are the father's species. Further, each unique litter is given a number. Apparent duplicates are due to multiple offspring born to each litter which were not uniquely identified. 2. genes: a description of pure P. campbelli (BB.BB), pure P. sungorus (SS.SS) or the F1 P. campbelli x P. sungorus (BB.SS) 3. age.day: the age each individual was when weighed 4. weight.g: the weight in grams of each individual 5. sex: the gender of each individual. Unknown for young individuals.Hamster_databaseData concerning crossing dates and number of offspring used to assess sex ratio. Data are in 7 columns: 1. cross number: in the form "BB.BB1" Letters represent species ( B=P. campbelli, S=P. sungorus ). The first two letters are the mother's species, the second two letters are the father's species. Further, each unique litter is given a number. 2. mother.number: mother's unique identification number. 3. father.number: father's unique identification number. 4. birthdate: when the litter was born. 5. female.number: number of female offspring in the litter. 6. male.number: number of male offspring in the litter. 7. total.litter.number: sum of males and females in the litterRaw imagesThese are the photos of every embryo and placenta referenced in the Embryo_Placenta_Weights file