6.3.3 Speciation

• Speciation is the process by which new species arise.
• Speciation explains how new species arise from existing ones over time.


  True
• Match the type of reproductive isolation with its explanation:

  Prezygotic mechanisms ↔️ Prevent mating or fertilization

  Postzygotic mechanisms ↔️ Result in inviable or infertile offspring
• Reproductive isolation can lead to genetic divergence between populations, resulting in speciation.


  True
• Prezygotic mechanisms include habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.
• Speciation occurs when a population divides and the two groups evolve differently to the point where they can no longer interbreed to produce fertile offspring.
• Reproductive isolation is a key mechanism that prevents interbreeding between populations, driving speciation.


  True
• What example is used to illustrate the role of environmental factors in speciation?

  Darwin's finches
• Match the type of reproductive isolation with its example:

  Habitat isolation ↔️ Two species live in different environments

  Temporal isolation ↔️ Two species mate at different times

  Behavioral isolation ↔️ Two species have different mating rituals

  Mechanical isolation ↔️ Two species have incompatible reproductive structures

  Gametic isolation ↔️ Two species have incompatible eggs and sperm
• Genetic differences accumulate over time due to reproductive isolation
• Geographical isolation leads to speciation when a population is physically separated by a barrier such as a mountain or river.

  True
• What is an example of allopatric speciation?

  Darwin's finches
• Sympatric speciation can occur through polyploidy or host-race formation
• Sympatric speciation can occur without geographical isolation if reproductive isolation arises.


  True
• Match the type of isolation with its definition:

  Geographical Isolation ↔️ Physical separation of populations

  Reproductive Isolation ↔️ Mechanisms preventing interbreeding
• Different mating behaviors can lead to reproductive isolation even in the same habitat.


  True
• Reproductive isolation includes both prezygotic and postzygotic mechanisms
• Match the type of speciation with its definition:

  Geographical Isolation ↔️ Physical separation leads to distinct gene pools

  Reproductive Isolation ↔️ Inability to interbreed due to incompatibility
• Reproductive isolation occurs when two populations of the same species can no longer interbreed and produce fertile offspring.
• Prezygotic mechanisms include habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.
• Steps of reproductive isolation:

  1️⃣ Prezygotic mechanisms prevent interbreeding

  2️⃣ Postzygotic mechanisms result in inviable offspring

  3️⃣ Genetic divergence accumulates

  4️⃣ New species unable to interbreed
• Genetic differences between isolated populations can lead to the formation of new, distinct species.


  True
• Darwin's finches in the Galápagos Islands evolved into distinct species due to the availability of different food sources.
• Examples of prezygotic mechanisms include habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.
• Prezygotic mechanisms prevent mating or fertilization
• What are examples of postzygotic mechanisms of reproductive isolation?

  Reduced hybrid viability ||| Hybrid infertility
• Steps leading to speciation through geographical isolation:

  1️⃣ Physical separation of a population

  2️⃣ Independent evolution of gene pools

  3️⃣ Reproductive isolation due to genetic differences

  4️⃣ Formation of new species
• Reproductive isolation occurs when members of a population can no longer interbreed
• Ring species are examples of allopatric speciation where populations form a continuous ring around a geographic barrier.


  True
• What is polyploidy in plants, and how does it relate to speciation?

  Chromosome doubling leads to reproductive isolation
• What are the two primary mechanisms driving speciation?

  Geographical and reproductive isolation
• Reproductive isolation prevents interbreeding between populations of the same species
• Arrange the types of speciation from broadest to most specific:

  1️⃣ Geographical Isolation

  2️⃣ Allopatric Speciation

  3️⃣ Reproductive Isolation

  4️⃣ Sympatric Speciation
• Allopatric speciation occurs without geographical isolation.

  False
• What is the primary driver of allopatric speciation?

  Geographical isolation
• The herring gull is an example of a "ring species."


  True
• Match the mechanism with its example in sympatric speciation:

  Polyploidy ↔️ Chromosome doubling in plants

  Host-race formation ↔️ Insects adapting to different hosts
• Geographical isolation creates distinct gene pools.
• What are prezygotic barriers in reproductive isolation?

  Prevent mating or fertilization
• How does speciation drive biodiversity?

  Creates genetically distinct populations