Concepts

Spread of disease between individuals through various mechanisms including spore dispersal

Transmission of parasites among individuals within social mammalian groups

Differences in environmental conditions and species composition between north and south-facing slopes

The increase in mortality with age, showing broad variation at the intraspecific level

Selection pressures that oppose each other within or between levels of biological organization

Non-random mating where individuals preferentially mate with similar individuals

Ecological relationships between bacteriophages and their bacterial hosts involving infection, replication, and lysis or lysogeny

Selection pressure imposed by predators that may favor optimal body sizes for escape ability