Table 2 Many of the documented examples of speciation in natural species fit the proposed model.

Fish

Salmonidae

Highly philopatric

Studies on MHC give conflicting results suggesting optimal outbreeding model

Cichlids

Bright colours typical of species are recessive (disappear in hybrids)

Close preference for kin, with no detectable inbreeding depression

Sticklebacks

EDA mutation (armour plate loss) is completely recessive

Pitx1 mutation (loss of pelvic structures) is recessive

Studies on MHC support optimal outbreeding model

Panmictic species (cod, macquerel, tuna...)

Susceptible to large and unpredictable fluctuations in numbers

Birds

Migrating birds are highly philopatric

Quail

Preferential mating among cousins (led to Bateson's optimal oubreeding)

Darwin's finches

High inbreeding coefficient due to small size of the niche

Mammals

Rate of speciation inversely related to the effective size of populations

Mice and rats

Very fragmented populations correlates with capacity to inbreed

Pikas

Optimal outbreeding

Insects

Haplodiploids (bees, ants, termites)

Very low mutations loads correlate with very high species richness, and global ecological success

Drosophila

Mating preferences are recessive (disappear in F1)

Assortative mating, and chromosomal rearrangements are more prominent between populations that are in close contact in the wild.

H. Carson highlighted the correlation of speciation with small populations based mostly on data from drosophila.

Apple maggot fly

Fruit preference is recessive (disappears in F1)

Heliconius mimetic butterflies

Sexual preference of the males is asymmetric, and linked to the recessive yellow colour

Plants

Selfing plants undergo more speciation, but the species go extinct more quickly

Monkey flowers

The red derived phenotype is recessive to the pink ancestral one