These are the changes of ARK: Survival Evolved’s Patch 188.0, grouped into categories for clarity. If not otherwise indicated, they’re quoted from the relevant Steam Thread.

Hunting

• Electronic Animal Trackers: Put it on anything you want to find again or track. Like yourself for finding the corpse after dying, or on an enemy for finding his base.

Multiplayer

• You can now host Non-Dedicated Sessions for smaller groups for coop playing.

Dinosaur Eggs

• Eggs are about 50% more common to find
• Eggs now last for 30 min on ground (prev was 20 min)

Taming

• Bronto now likes a certain Kibble 😉

Performance

• Massive performance improvement to structural integrity calculation (namely, less lag/stalls on the server when destroying/replacing pieces of large connected structures)

Bugfixes

• Fixed pop-in of underwater cave meshes
• Fixed a bug with structure limits (PhysX overlap limit was being exceeded), and reset the default value to 6000 (should cover even the biggest current bases that we’ve seen on Official Servers). The new configurable/commandline value is: NewMaxStructuresInRange=6000
• Swimming backwards on a dino no longer desyncs with the server
• Tamed Scorp shouldn’t drown anymore. In fact various tamed dinos that were not swimming to the surface should now try to stay on the surface when not being ridden.
• Fixed pop-in of underwater cave meshes

Painting

• New Structure: “Single Panel Flag” which is a simple flag that has one solid panel canvas, handy for custom painting onto.
• You can now Draw anything you want on a sign! In Multiplayer simultaneous.
  

  Real-time simultaneous per-pixel painting coming to an ARK near you! <3 @garrynewman http://t.co/mOTFDZTxR7 #playARK pic.twitter.com/z3HOXSuwrs

  — ARK (@survivetheark) 17. Juli 2015

 

(Original Announcement on Steam)

Here are the patchnotes of the previous patch (187.22)