Summary
Gene exchange between species blurs lines, as in polar and grizzly bear hybrids.
In depth
Hybrid zones show how barriers vary. Introgression can transfer adaptive alleles (e.g. high-altitude gene EPAS1 from Denisovans to Tibetans). Hybridisation can swamp rare species.
Hybrid zones can be stable or move. Hybrid vigour or inviability may occur. Hybridisation can transfer useful genes.
Remember: species can exchange some genes yet remain distinct.
Hybridisation occurs when individuals from different species or populations interbreed. About 10 percent of animal and 25 percent of plant species hybridise with others. Outcomes range from sterile offspring, as in mules, through hybrid zones where parent species meet, to introgression, the transfer of genes between species via backcrossing, and sometimes hybrid speciation.
Examples include polar and grizzly bear hybrids (pizzly bears), modern humans carrying Neanderthal and Denisovan DNA, Darwin's finches and Heliconius butterflies sharing wing pattern genes. Hybridisation can add beneficial variation but can also swamp rare species, as with the Scottish wildcat. It challenges the biological species concept.
Key idea: species boundaries are often semi-permeable.
Frequently asked questions
What is Hybridisation and Species Boundaries?
Gene exchange between species blurs lines, as in polar and grizzly bear hybrids.
Which area of biology covers Hybridisation and Species Boundaries, and how advanced is it?
Hybridisation and Species Boundaries is one of the 52 topics in Taxonomy & Biodiversity. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Species, Genetic Rescue, Biogeographic Regions.
Can you give an example of Hybridisation and Species Boundaries?
Coyote-wolf hybrids in eastern North America.
What should I learn before Hybridisation and Species Boundaries?
Work through the Beginner topics in Taxonomy & Biodiversity first, such as Taxonomy, Binomial Nomenclature, Taxonomic Hierarchy, then return to Hybridisation and Species Boundaries. Advanced topics assume the Intermediate vocabulary.
What topics are related to Hybridisation and Species Boundaries?
The closest topics to Hybridisation and Species Boundaries are Species, Genetic Rescue, Biogeographic Regions, Biodiversity and Ecosystem Function. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Hybridisation and Species Boundaries?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Hybridisation and Species Boundaries. To practise the whole of Taxonomy & Biodiversity, use the Taxonomy & Biodiversity quiz.
How is Hybridisation and Species Boundaries different from Species?
Hybridisation and Species Boundaries: Gene exchange between species blurs lines, as in polar and grizzly bear hybrids. Species: A basic unit of classification; organisms that can interbreed and produce fertile offspring. Read both side by side and note what each one explains.
How should I study Hybridisation and Species Boundaries step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Species and explain the difference aloud. Finally, take the Taxonomy & Biodiversity quiz and come back to this page for any question you miss.