Isolation and Speciation

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