Bio 161 Ecology and Evolution

Macroevolution

Speciation

Species =Groups of actually (or potentially)

interbreeding natural populations that are reproductively isolated from other

such groups.Ernst Mayer.

Population genetic translation:a single gene pool.

? Morphological or Genetic Species

Bufo woodhousie(Fowlers toad)streams

Bufo americanus(American toad)

Rain puddles

Progomphus obscurus:rivers and streams

Progomphus alachuenis:lakes

Quesrcus lobataCalifornia valey oak

Moist mountain slopes

Quercus dumosaShrub oak

Dry chaparral

Rana sylvaticus(Wood frog)

Rana pipiens(Leopard frog)

Lactuca graminifolia:Flowers in early Spring

Lactuca canadensis:Flowers in Summer

Two species of wild lettuce growing together along roadsides throughout southeastern US.

Salvia mellifera Salvia apiana

Horse Mule Donkey

Zebrass

Colonization and founder effect.

Barriers to movement

Extinction of intermediate populations

Allopatric speciation of pupfishes (Cyprinodon) in Nevada desert pools.

Desert Pupfish. These fish are about the size of guppies and live in various small pools in this part of Nevada and California. Each pool has its very own distinct species of Pup Fish and all are endangered.

Distribution of Pupfish

Allopatric speciation of Hawaiian goose (the Nene)

Pollinator switching in species with highly specialized pollination mechanism may also lead to sympatric speciation. The two orchids above are very similar and have completely overlapping ranges, yet are pollinated by different species of solitary bees. In this genus, pollinators are attracted by the flowers' species-specific chemical attractants that mimic the female pheromones of the targeted insects. Left, Yellow-bee Orchid (Oprys lutea), right, Ophrys sicula. The latter species was regarded as a variant of the former for long.

Horse Mule Donkey

2n = 18

2n = 18

2n = 36

Galeopsis pubescens(2n = 16)

Galeopsis speciosa(2n = 16)

(2n = 32)

Hemp nettle (G. pubescens x G. speciosa)

Sympatric speciation and allopolyploidy in wheat.

Sympatric speciation with alloploidy of Gilia species.A hybrid zygote Gilia major (n=18) resulted from a cross between G. aliquanta (n=9) and G. minor (n=9) followed by genome duplication.

Fig. 22.14

Rapid speciation because of:

1.Adaptation to a new environment

2.Genetic drift

3.Character displacement:a) Resource partitioningb) Building pre-zygotic

isolation mechanisms.

Fig. 22.13

Fig. 22.15

Convergent Evolution

OrdovicianDevonian

Permian

TriassicCretaceous

Siberian Traps

The End.