The new populations are named after each map they appear on. For instance, the finale of The Parish is called "c5m5_bridge", so the population for it is now "c5m5".

Dead Center:
c1m1
c1m2
c1m3
c1m4

Dark Carnival
c2m1
c2m2
c2m3
c2m4
c2m5

Swamp Fever
c3m1 + c3m1_deepswamp
c3m2 + c3m2_parachutist
c3m3
c3m4

Hard Rain
c4m1
c4m2
c4m3
c4m4
c4m5

The Parish
c5m1
c5m2
c5m3
c5m4 + c5m4_ceda
c5m5

The Passing
c6m1 + c6m1_wedding
c6m2 + c6m2_bikers
c6m3

The Sacrifice
c7m1 + c7m1_intro + c7m1_arena + c7m1_freighter
c7m2 + c7m2_arena + c7m2_freighter
c7m3

No Mercy
c8m1
c8m2
c8m3 + c8m3_sewer + c8m3_hospital
c8m4 + c8m4_construction
c8m5

Crash Course
c9m1
c9m2

Death Toll
c10m1
c10m2 + c10m2_sewer
c10m3
c10m4
c10m5

Dead Air
c11m1
c11m2
c11m3 + c11m3_construction + c11m3_police + c11m3_maintenance
c11m4
c11m5

Blood Harvest
c12m1
c12m2
c12m3
c12m4
c12m5

Cold Stream
c13m1
c13m2 + c13m2_deepswamp
c13m3 + c13m3_busstation + c13m3_deepswamp
c13m4 + c13m4_deepswamp + c13m4_waterworks

Last Stand
c14m1 + c14m1_junkyard + c14m1_junkyardroad + c14m1_estuary
c14m2 + c14m2_lighthouse