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How do new species arise?

This overview explores the fascinating process of speciation, wherein new species arise through reproductive isolation and distinct adaptations. We delve into the biological and ecological concepts of species, emphasizing populations' potential for interbreeding and their roles in ecosystems. Examples such as Darwin’s finches and Hawaiian honeycreepers illustrate adaptive radiation and the importance of geographic isolation in species development. Additionally, we examine the significance of reproductive barriers, including hybrid viability and reproductive isolation, in maintaining species integrity.

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How do new species arise?

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  1. How do new species arise? Speciation

  2. What is a species? • Biological concept of species • a population or group whose members have the potential to interbreed and produce fertile offspring • Ecological concept of species • identifies species in terms of their ecological niches, focusing on unique adaptations to particular roles in biological communities

  3. SPECIATION • The formation of new species • As new species evovlve, populations become reproductively isolated • Reproductive barriers keep species separate • Reproductive isolation – members of 2 populations cannot interbreed & produce fertile offspring.

  4. Table 23.1a

  5. Table 23.1b

  6. Tigon Result of male tiger and female lion mating incaptivity. Offspring are infertile. Tigers and lions are eparated both geographically and ecologically.

  7. Liger Result of male lion and female tiger mating in captivity. Offspring are infertile.

  8. Fig. 23.6 Four species of leopard frogs: differ in their mating calls. Hybrids are inviable.

  9. These squirrels live on opposite sides of the Grand Canyon. This is an example of speciation.

  10. SPECIATION IN DARWIN’S FINCHES • Speciation in the Galapagos finches occurred by: • founding of a new population, • geographic isolation which led to reproductive isolation • changes in the new population’s gene pool due to competition.

  11. Hawaiian Honeycreepers An example of adaptive radiation – these species all diverged from a common ancestor (founder species) FOUNDER SPECIES

  12. Phylogeny • the evolutionary history of a group • based on homologous structures and molecular sequences

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