Allopatric speciation Harris’ groundsquirrel White-tailed ground squirrel

Allopatric speciation Kaibob squirrel Albert’s squirrel

Hawaiian Drosophila

Speciation due to dispersal . . . Fig. 22.16

. . . can give rise to huge numbers of species. Adaptive radiation. Fig. 24.11

Speciation in the lab Fig. 24.12

Fig 23.1

Wind direction high Tolerance to metals low Adults Off mine tailings Adults On mine tailings

Sympatric speciation? Many species in small isolated, bowl-shaped lake. Schliewen, et al. 2001. Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, Cameroon. Molecular Ecology 10:1471.  

Sympatric speciation ??

Sympatric Speciation Closely related species often sympatric Disruptive selection Assortative mating

Polyploidy Fig 24.13 Self fertilization New species 2n = 6 with 2n = 12 2n = 6 Error during meiosis makes gametes with n = 6

Gametes Zygote - infertile

2n = 14 2n = 28

IV. Macroevolutionary Pattern A. Tempo of Speciation 1. gradualism 2. punctuated equilibrium B. Phylogenetic Reconstruction 1. an example 2. the problem of convergent evolution 3. molecular traits

Fig. 24. 17

salamander frog mouse lizard snake bird A E C B D

Current species: salamander frog mouse bird lizard snake E D B C A

ancestors: salamander frog mouse bird lizard snake E D B C A

Fig 22.14 humerus ulna radius carpals phalanges

Some snake species still have non-functional pelvis bones and little leg bones.

Source: Ray Troll, in Matsen and Troll 1994 Planet Ocean Source: Ray Troll, in Matsen and Troll 1994 Planet Ocean. Ten Speed Press, Berkeley.

The problem of convergent evolution: the Tasmanian wolf is more closely related to the kangaroo than it is to the North American red wolf Tasmanian Wolf Red Wolf

Homeobox (Hox) genes have same order, structure and similar pattern of expression in mouse and fly!