Recessive and dominant traits have nothing whatsoever to do with either fitness or frequency. Recessive traits can be more common either non-randomly through natural selection or randomly through genetic drift
Pioneer species can decrease if other species move it out. If the pioneer species in a forest area is a type of bush, that bush might decrease in number as more species come in.
It takes the Earth (approximately) 364.25 days to revolve around the sun. That's why we have leap days.
Hope that helps!
It is the metric unit of measurement for temperature.