Examples of hybrid speciation in the following topics:
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- Speciation occurs over a span of evolutionary time.
- This term is used because the low success of the hybrids reinforces the original speciation.
- Over time, via a process called hybrid speciation, the hybrids themselves can become a separate species.
- With DNA analysis becoming more accessible in the 1990s, hybrid speciation has been shown to be a fairly common phenomenon, particularly in plants.
- After speciation has occurred, the two separate-but-closely-related species may continue to produce offspring in an area called the hybrid zone.
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- Many species are similar enough that hybrid offspring are possible and may often occur in nature, but for the majority of species this rule generally holds.
- In fact, the presence in nature of hybrids between similar species suggests that they may have descended from a single interbreeding species: the speciation process may not yet be completed.
- Biologists have proposed mechanisms by which this could occur that fall into two broad categories: allopatric speciation and sympatric speciation.
- Sympatric speciation (sym- = "same"; -patric = "homeland") involves speciation occurring within a parent species remaining in one location.
- Define speciation and discuss the ways in which it may occur
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- Sympatric speciation can begin with a chromosomal error during meiosis or the formation of a hybrid individual with too many chromosomes, such as polyploidy which can occur during whole-genome duplication.
- An example would be the recent speciation of allopolyploid Spartina — S. anglica; the polyploid plant is so successful that it is listed as an invasive species in many regions.
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- The process of speciation within the same space is called sympatric speciation.
- A number of mechanisms for sympatric speciation have been proposed and studied.
- One form of sympatric speciation can begin with a serious chromosomal error during cell division.
- In this way, sympatric speciation can occur quickly by forming offspring with 4n: a tetraploid.
- Notice how it takes two generations, or two reproductive acts, before the viable fertile hybrid results.
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- Two patterns are currently observed in the rates of speciation: gradual speciation and punctuated equilibrium.
- In terms of how quickly speciation occurs, two patterns are currently observed: the gradual speciation model and the punctuated equilibrium model.
- In the gradual speciation model, species diverge gradually over time in small steps.
- The primary influencing factor on changes in speciation rate is environmental conditions.
- In (a) gradual speciation, species diverge at a slow, steady pace as traits change incrementally.
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- Reproductive isolation, through mechanical, behavioral, and physiological barriers, is an important component of speciation.
- Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages; this is called hybrid inviability.
- In another postzygotic situation, reproduction leads to the birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own; this is called hybrid sterility.
- Speciation can occur when two populations occupy different habitats.
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- Allopatric speciation occurs when a single species becomes geographically separated; each group evolves new and distinctive traits.
- This is known as allopatric speciation.
- Scientists have documented numerous cases of allopatric speciation.
- These variances can lead to evolved differences in the owls, resulting in speciation.
- The owl is an example of allopatric speciation.
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- In order to explain the bonding, the 2s orbital and two of the 2p orbitals (called sp2 hybrids) hybridize; one empty p-orbital remains.
- sp2 Hybridization in Ethene and the Formation of a Double Bond
- In this case, carbon will sp2 hybridize; in sp2 hybridization, the 2s orbital mixes with only two of the three available 2p orbitals, forming a total of three sp hybrid orbitals with one p-orbital remaining.
- The carbon atoms are sp2 hybridized.
- Recognize the role of sp2 hybridized atoms in sigma and pi bonding.
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- sp3 hybrid orbitals form when a single s and three p orbitals hybridize.
- In hybridization, carbon's 2s and three 2p orbitals combine into four identical orbitals, now called sp3 hybrids.
- For example, in the ammonia molecule, the fourth of the sp3 hybrid orbitals on the nitrogen contains the two remaining outer-shell electrons, which form a non-bonding lone pair.
- Ethane can form by replacing one of the hydrogen atoms in CH4 with another sp3 hybridized carbon fragment.
- Explain the process of hybridization as it applies to the formation of sp3 hybridized atoms.
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- In chemistry, hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for describing bonding properties.
- The hybrids are named for the atomic orbitals involved in the hybridization.
- For this molecule, carbon will sp2 hybridize.
- In this case, sp hybridization leads to two double bonds.
- Describe the role of hybridization in the formation of double and triple bonds.