= Solution
Examples of \b[<prezygotic reproductive isolation>], all acting before a zygote forms, include:
* \b[Habitat isolation:] potential mates occupy different habitats or hosts and seldom encounter each other at mating sites.
* \b[Temporal isolation:] breeding seasons, flowering times or daily mating periods differ, reducing opportunities for mating or pollen transfer.
* \b[Behavioral isolation:] courtship signals, calls or chemical mating signals elicit responses mainly from the same species, preventing cross-group mating.
* \b[Mechanical isolation:] incompatible mating structures or flower–pollinator fit prevent successful transfer of gametes.
* \b[Gametic incompatibility:] gametes meet but cannot recognize, fuse or complete <fertilization> successfully.
The first four primarily reduce mating or gamete transfer; the last can occur after mating while still preceding <fertilization>. These differ from <postzygotic isolation>, such as hybrid inviability or hybrid sterility, which acts after the zygote has formed. Distinguishing these stages prevents “premating” from being used as a synonym for every prezygotic barrier.
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