The Different Finch Species in the Phylogeny Shown in the 22.8

question 62

Essay

The different finch species in the phylogeny shown in the 22.8 of the textbook have all evolved on islands of the Galápagos archipelago within the past 3 million years.Molecular clock analysis (see Chapter 23) has been used to determine the dates of the various speciation events in the phylogeny.Geological techniques for dating rock samples (see Chapter 24) have been used to determine the ages of the various Galápagos islands.The table shows the number of species of Darwin's finches and the number of islands that have existed in the archipelago at several times during the past 4 million years. If no more islands form in the Galápagos archipelago, do you think that speciation by geographic isolation will continue to occur among Darwin's finches? Why or why not? What additional data could you collect to test your hypothesis (without waiting to see if speciation occurs)?

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Definitions:

Antigen Presenting Cells

Cells that display foreign antigens complexed with major histocompatibility complex molecules on their surfaces.

Progenitor

An ancestor or parent in a direct line of descent, or a cell that has the capacity to differentiate into a specific type of cell.

Plasma Cell

Cell that secretes antibodies; a differentiated B lymphocyte (B cell).

Dendritic Cells

Antigen-presenting cells that process antigen material and present it on the surface to T cells, playing a crucial role in the immune response.