Table 3 Study quality assessment criteria
Design feature | Study attribute | |
|---|---|---|
Internal validity of study | Comparator and exposure crosses | * Did exposure (inbred) crosses take place contemporaneously with control (non-inbred) crosses? Yes: 1 point, otherwise: 0 points |
1. Were the pedigrees underpinning all the crosses known (because of experimental manipulation; 1 points), or unknown (0 points)? | ||
Scale of evidence for relative level of inbreeding between exposure and comparator groups | 2. Was the coefficient of inbreeding known for both the exposure and comparator crosses? No pedigree information or physical distance used as proxy, for relative inbreeding level (0 points). Inbreeding coefficient or pedigree known for exposure (1 point). Known for both (2 points) | |
Outcome measure | 3. Were the outcome measures components of fitness (survival, fecundity, viability; 1 point), or indirect measures of these (e.g. growth rate, body mass, size; 0 points)? | |
Environment for trait measurements | 4. Were the traits measured in the field (2 points), under experimental conditions that closely approximate field conditions (1 point), or under non-native experimental conditions (0 points)? | |
Study populations | * Were populations selected randomly or using sampling that was stratified over variation in population location, distribution or size (1 point, otherwise 0 points)? | |
5. Was the cost of inbreeding observed in multiple study populations (1 point; 0 points otherwise)? | ||
Selection of individuals for crossing experiments, or selection of natural observed crosses | * Were crosses selected randomly from a population of possible crosses, or was selection stratified over variability in location or timing of crosses (1 point; otherwise 0 points)? | |
External validity of study | Observation window for progeny individuals | 6. Were the fitness consequences of inbreeding within progeny tracked until at least the F2 generation (1 point; otherwise 0 points)? |
Status of populations studied | * Did the study include re-introduced, or naturalized population(s)? 1 point if all populations were naturally founded, otherwise 0 points |