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Isolation and Speciation
Isolation and SpeciationMacroevolution in action!1Formation of a new species what is a Species?Many definitions of species existMorphological based on finding physical/structural similaritiesAdvantages: applies to both sexual/asexual organismsDisadvantage: subjectiveEcological based on the niche of an organism (its role in ecosystem)Phylogenetic based on an animals ancestry/genetic historyCompare physical characteristics/molecular similaritiesPaleontological focus on morphologically-discrete species known only from the fossil record2Biologic Species conceptDefined as:Population/group of populations that can successfully interbreed, producing viable, fertile offspring
Speciation often requires major genetic changes
Hinges on reproductive isolation something that keeps two groups that would normally interbreed from doing soAllopatric vs. Sympatric SpeciationAllopatric - away from ones fatherlandPhysical barrier divides 1 population into twoMountains, channels, islands, rivers, lava flows, etc.Leads to a divergence of the gene pool through mutations, selection, etc.
If enough time passes, will likely be unable to mate if reintroduced
Sympatric SpeciationSpecies evolves while alongside its fellow organisms.How?PolyploidyHabitat differentiationSexual selection
Reminder: zygote = fertilized egg
5Reproductive IsolationLeads to speciationBy preventing gene flow among populationsPrezygotic Isolation prevents fertilizationMechanicalHabitatBehavioralMating songsTemporalGameticPolyploidy (plants)
6Mechanical
Habitat
Behavioral
Temporal
Gametic
Post-Zygotic IsolationFertilization has occurred, but the hybrid isnt viable, cant reproduceReduced hybrid inviability development/survival of hybrids is impairedReduced hybrid fertility hybrids fail to produce functional gametesHybrid breakdown offspring of hybrids are feeble/infertile12Some examples of hybrids that are infertile (sterile)Cool stuff! (Male partner listed first)13Camel + Llama =14Cama
15Tiger + lion = 16Tiglon!
17Lion + tiger =18Liger
19Zebra + horse = 20Zebroid
21Donkey + horse =22Mule
23Horse + Donkey =24Hinney
25False Killer Whale + Dolphin26Wolphin
27Leopard + Lion =28Leopon
29Grizzly + Polar BearGrolar/ Pizzly
Goat + Sheep = 32Geep
33Cattle + Bison=
Beefalo
Human + Chimpanzee = 36Humanzee?
37