story identification - SciFi book series about a collection of humans who get taken by a lightning quick alien race

Looking for the name of a series of novels I read a two or three years ago. I think the books where relatively new (no older then 10-15 years) as the tech in the books where not outdated scifi.

The series was at least 3 books, but I think there may have been more.

A brutal species of alien determined to be the quickest, strongest, most brutal... individuals possible, takes a group of humans from their colony ship(?) and places them on the aliens "sacred" planet. "Sacred" because of the local fauna being the only threat the aliens have found in the galaxy that surpasses their own prowess.

After a period of time the aliens leave and forget about the weak humans, thinking they will die anyways. The humans do not die, but instead take genes and inspiration from the local fauna (carbon nano tube bones, superhuman reactions, speed, strength and so on).

Think one of the books are named the same as the aliens named the planet.

Answer

This sounds remarkably like the Koban series by Stephen W Bennett

We colonized seven hundred planets. Humankind enjoyed the benefits of expansion room and the end of wars. We even disbanded our military.

Then the Krall found us.

The Krall have used thousands of years of combat to select the genes of the strongest and fastest warriors. They are a species determined to dominate the entire galaxy, through destruction and annihilation of every opponent.

Koban is an uninhabited high gravity planet with impossibly fast savage animals, which employ organic superconducting nerves. This deadly world is where the Krall tested humans for war capability. We are useful only if we can fight well. If not, they will destroy us swiftly, as they have others. They already have slave races, and we are poor tasting meat animals. The Krall will use us, if worthy, to seek physical perfection using the attrition of war, one planet at a time.

Growing weary of human physical weakness, the ruthless Krall are on the verge of a decision to eliminate our race quickly. A ship containing bio-scientists is captured for combat testing on Koban. The urgent choice for Captain Mirikami and the scientists is simple: Prove we can produce better, smarter fighters, or humanity is doomed to rapid extermination, rather than the slow eradication the Krall prefer.

There are 7 books in the primary series as it happens

1. Koban (2012)


2. The Mark of Koban (2013)


3. Rise of the Kobani (2013)


4. Shattered Worlds (2014)


5. A Federation Forged in Fire (2015)


6. Conflict and Empire (2016)


7. When Empires Collide (2017)