Evolutionarily protochordates may be intermediate animals between invertebrates and vertebrates. Imagine a scientist is testing the hypothesis that vertebrates evolved from echinoderms. Having as research object a newly found protochordate species, what is an example of a discovery that would weaken the hypothesis? What is an example of a discovery that would strengthen it?
Hypothesis to be tested: Vertebrates evolved from echinoderms. Testing material: A newly found protochordate species (i.e., a vertebrate forerunner). Example of weakening observation (that puts the new protochordate species evolutionarily far from echinoderms): “The new species is protostome”, as opposed to echinoderms, that are deuterostomes. This observation brings the suspicion that deuterostomy in vertebrates is independent in origin from echinoderms. Example of strengthening observation (that nears the new protochordate species to echinoderms): “The new species has secondary radial symmetry”, similar to echinoderms. This observation makes stronger the hypothesis that echinoderms and vertebrates are relatives. (This item shows how science works, beginning with the placement of hypothesis and further observational testing.)
