Over Evolutionary History, Many Groups of Organisms That Inhabit Caves

question 19

Essay

Over evolutionary history, many groups of organisms that inhabit caves have lost the organs of sight.For instance, although surface-dwelling crayfishes have functional eyes, several crayfish species that are restricted to underground habitats lack eyes.Opsins are a group of light-sensitive proteins known to have an important function in vision (see Chapter 45), and opsin genes are expressed in eye tissues.Opsin genes are present in the genomes of eyeless, cave-dwelling crayfishes.Two alternative hypotheses that might explain the presence of opsin genes in an eyeless organism are: (1) the genes are no longer experiencing purifying selection because there is no longer selection for function in vision; and (2) the genes are experiencing selection for a function other than vision.How would you investigate these two hypotheses, using the sequences of the opsin genes in various species of crayfishes?

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Definitions:

Traditional Notions

Established beliefs or ideas typically passed down through generations or deeply embedded in social practices.

Cultural Bias

The tendency to interpret and judge phenomena by standards inherent to one's own culture, often leading to misunderstanding or discrimination against other cultures.

Test Score Reliability

The degree to which an assessment tool produces stable and consistent results over repeated applications or instances.

Internal Inconsistency

A situation where there are contradictions within a theory, argument, or in the behavior or beliefs of an individual, leading to confusion or lack of reliability.