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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- 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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- 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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- 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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- Biodiversity has been affected by five mass extinction periods, which greatly influenced speciation and extinction rates.
- The number of species on the planet, or in any geographical area, is the result of an equilibrium of two evolutionary processes that are ongoing: speciation and extinction.
- When speciation rates begin to outstrip extinction rates, the number of species will increase; likewise, the number of species will decrease when extinction rates begin to overtake speciation rates.
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- Changes in the environment often create new niches (living spaces) that contribute to rapid speciation and increased diversity.
- Late in the Cenozoic, further extinctions followed by speciation occurred during ice ages that covered high latitudes with ice and then retreated, leaving new open spaces for colonization.
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- Gene flow strongly acts against speciation, by recombining the gene pools of the groups, and thus, repairing the developing differences in genetic variation that would have led to full speciation and creation of daughter species.