Anthropogenic habitat alteration creates novel environments that can alter selection pressures.
Global environmental change is expected to alter selection pressures in many biological systems1,2,3, but the long-term molecular and life history data required to quantify changes in selection are rare4.
Consequently, variation in the age-trajectories of survival and fertility among populations do not greatly alter selection on alleles involved in susceptibility to late-onset diseases (in agreement with results from [3]), unless such changes alter the effective population size.
As all forms of female mate choice can significantly impact the strength and direction of sexual selection, any variation based on female age or experience may have important evolutionary implications that may alter selection for multiple male sexual traits [8], [14].
Any of these changes might decrease population size and alter selection, which might then cause maladaptation and reduced genetic variation (Johansson et al. 2007; McClure et al. 2008).
The present volume amplifies these intuitions by showing how human influences on salmon populations and their habitats can alter selection and lead to phenotypic change.
In animals, population density may also alter selection on mating systems and sexual aggression traits (Emlen and Oring 1977; Maher and Lott 2000; Kwiatkowski and Sullivan 2002; Horiuchi 2008; Knell 2009).
Hence, in temperate zone organisms relying on strong seasonal changes in the ecosystem, one would expect climate change to alter selection on phenology and generally to lead to directional selection for earlier breeding and migration.
Modern breeders have used these theoretical findings to alter selection methods to incorporate IGEs, significantly improving yield and animal welfare by antagonistic interactions between penned animals that are a primary source of mortality and lower yield.
A brief subjective and objective assessment will also be performed at the start of each subsequent treatment session to gauge response to treatment, re-identify treatment priorities and alter selection of techniques and exercises.
For example, some populations have a short freshwater residency but a long estuarine residency, which should shift the stage and environment where climate change is most likely to alter selection pressures.
