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Lab: A Step in Speciation What is a species? Species: organisms that can interbreed and produce fertile offspring. What are subspecies? Subspecies: members of the same species that are geographically isolated from each other and look different. Question What happens to different subspecies when they are geographically isolated from each other? Hypothesis IF subspecies are geographically isolated, THEN that will lead to speciation or the formation of a new species. Procedure 1. 2. 3. Plot out your grid map according to the instructions. Once that is done, place the salamander pictures in their proper locations on the map. Answer analysis questions. Analysis – Part A 1. 2. 3. No, areas without salamanders probably are dry or desert like. Also, human populations might disrupt their habitats. Mountain areas, except for in mountainous desert areas. Yes, subspecies are geographical variations with in a species. Subspecies closer together should be more similar to each other than to those further away. You can see similarities among coastal forms versus inland forms (closest to ancestral species = E.e. picta). Analysis Part A (cont.) 4. 5. Spotted forms tend to be inland and unspotted forms along the coast, except in southern California where both spotted and unspotted occur together. Both populations occur in the same area in southwestern California. Analysis - Part B 1. They are genetic intergrades (hybrids) between subspecies. Analysis – Part B (cont.) 2. An intergrade between E.e. eschscholtzii and E.e. xanthopica -yellow eye patch disappears -less orange coloration on belly -dots on sides (yellow, black) -tip of tail lighter Analysis – Part B (cont.) 3. They are geographically isolated by several hundred miles. 4. To find any intergrades and to see if two subspecies occupied the same region. 5. There are no intergrades – more collections needed? Analysis – Part B (cont.) 6. 7. Population E.e. klauberi because this is the only form without intergrades. Between populations E.e. klauberi and E.e. croceator. Analysis – Part B (cont.) 8. The map shows intergrades between all the subspecies except the two that exist in southern California. It appears that speciation has taken place down the coastal and inland mountain ranges. Before data on the intergrades was collected it would be easy to think that the two southern subspecies were different species. Analysis – Part B (cont.) 9. It would break the chain of interbreeding subspecies E.e. eschscholtzii and E.e. klauberia in the southern end of the range. This would produce two reproductively isolated populations – two species.