Ensatina eschscholtzii is a species of salamander that lives in woodland ecosystems in California, USA. Populations of E. eschscholtzii are separated by the Central Valley, shown in Fig. 6.2, which contains conditions unsuitable for salamanders. Some scientists think that the separated populations of E. eschscholtzii have evolved to form different species of salamander. Individuals from different salamander populations may not be able to reproduce with each other, even if they are able to interact. Explain how salamanders from different populations have evolved to be unable to reproduce with each other. . . . . . .

Biology

IGCSE&ALevel

CAIE

Exam No：9700_s25_qp_44 Year：2025 Question No：6(c)

Answer:

Knowledge points:

17.3.1 outline the theory of evolution as a process leading to the formation of new species from pre-existing species over time, as a result of changes to gene pools from generation to generation

17.3.2 discuss how DNA sequence data can show evolutionary relationships between species

17.3.3.1 geographical separation (allopatric speciation)

17.3.3.2 ecological and behavioural separation (sympatric speciation)

18.1.1 discuss the meaning of the term species, limited to the biological species concept, morphological species concept and ecological species concept

18.1.2 describe the classification of organisms into three domains: Archaea, Bacteria and Eukarya

18.1.3 state that Archaea and Bacteria are prokaryotes and that there are differences between them, limited to differences in membrane lipids, ribosomal RNA and composition of cell walls

18.1.4 describe the classification of organisms in the Eukarya domain into the taxonomic hierarchy of kingdom, phylum, class, order, family, genus and species

18.1.5 outline the characteristic features of the kingdoms Protoctista, Fungi, Plantae and Animalia

18.1.6 outline how viruses are classified, limited to the type of nucleic acid (RNA or DNA) and whether this is single stranded or double stranded

Answer:

Knowledge points:

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