I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
Oceanic crust is thinner and denser than continental crust.
It can date back as far as the dinosaur age...
Johannes Kepler was the one who elucidated the 3 laws of planetary orbits, the chief one being the elliptical orbits of the planets around the sun with the sun at a focal point at one end of the orbits. This was derived especially from careful observations by Tycho Brahe of the heavens and based on his model of the orbits so was scientifically based.
Answer: These are known as <u>pathogens.</u>
Additional:
- Anthrax is caused by <u>Bacillus anthracis</u>
- Strep throat is caused by <u>Streptococcus pyogenes</u>
- Tetanus is caused by <u>Clostridium tetan</u>
<u></u>
I hope my answer helped ⛄️
