Cormack–Jolly–Seber model with environmental covariates: A P‐spline approach

In capture–recapture models, survival and capture probabilities can be modelled as functions of time‐varying covariates, such as temperature or rainfall. The Cormack–Jolly–Seber (CJS) model allows for flexible modelling of these covariates; however, the functional relationship may not be linear. We extend the CJS model by semi‐parametrically modelling capture and survival probabilities using a frequentist approach via P‐splines techniques. We investigate the performance of the estimators by conducting simulation studies. We also apply and compare these models with known semi‐parametric Bayesian approaches on simulated and real data sets.     

Optimising multi-tier open nucleus breeding schemes

Summary The constant migration (CM) method and the ebv migration (EBVM) method of optimising the design of multi-tier open nucleus breeding schemes are presented and compared. The equation for the equilibrium rate of genetic gain of a three-tier open nucleus scheme is determined using the CM method. The major advantage of the EBVM method is the reduction in the number of parameters which have to be varied in order to locate the maximum equilibrium rate of genetic gain. For the CM method for the number of variable parameters is 5, 14, 27 and (2n + 1) (n - 1) for unrestricted male and female migration in schemes with 2, 3, 4 and n tiers respectively. The corresponding number of variable parameters for the EBVM method is 1, 2, 3 and n-1 respectively. A procedure is given for the EBVM method so as to accomodate variance loss due to selection and variance gain due to the mixing of groups with a different mean breeding value.