Behavioral Isolation Continued Example Lacewings Example Firefly Example Anole Lizard 3 species are identical but they produce different sounds The sound they make determines if a female will mate with them The wrong sounds means the female will not mate with the male Males flash lights in a particular way Each species has a different sequence The flashing lights also attract predators like a female from a different species They have dewlaps or gular fans Male anoles pump their fans and do push ups The pattern is specific to the species This can also attract predators Temporal Isolation Breeding of similar closely related species at different times of the year Wild lettuce late summer early spring Example Gryllus Cricket Prevention of gamete fusion still pre zygotic Sperm cannot penetrate egg Toxic uterine environment sperm killed by biochemical agents Post Zygotic Isolation Hybrid inviability hybrid infertility Inviability birth Infertility o Accumulation of genetic defects in zygote the offspring dies in utero in egg or after o Offspring survive become adults but infertile sterile o Can also be partially infertile will be discussed later Horse Donkey Mule better work animal but is incapable of reproduction Tiger Lion Liger and Tigon can sometimes produce viable offspring Leopard Frogs Clear geographical isolation Temporally isolated Behavioral isolation different calls Ecological isolation breed in different habitats There is usually more than one type of isolation acting on different populations all lead to genetic divergence as it increases there is an increase in the likelihood of speciation Speciation Requires multiple steps o Populations of a single species become isolated from each other and over time these populations begin to diverge genetically o Changes in each gene pool relating to changes in allele frequency driven by natural selection loss of gene flow genetic drift population specific mutations o If divergence has occurred and they can no longer mate they re now separate species Beetle Example Population A Population B Gene Flow River isolates them Years later river dries out 2 different species
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