30-Macroevolution Flashcards
What interpretations can be given in the fossil record?
Gaps represent macromutation, followed by replacement. OR gaps represent rapid gradual change that cannot be recovered from a coarse fossil record.
What is the difference between punctuated equilibrium and phyletic gradualism?
They are two extremes along a continuum. Punctuated does not undergo much change for a long time and then suddenly changes. Phyletic is when new species are coming about gradually.
What are paedomorphosis and heterochony, and how do they bear on the question of phyletic gradualism?
Paedomorphosis: The retention of juvenile features in the adult animal. Ex. Ambystoma salamanders. This is associated with more constant environments.
Heterochony: Differential growth of different body parts.
Phyletic gradualism assumes that intermediate forms are adaptive.
What are Hox genes?
Hox genes: A group of related genes that control the body plan of the embryo along the anterior-posterior (head-tail) axis. After the embryonic segments have formed, the Hox proteins determine the type of segment structures that will form on a given segment.
How do wing-propelled diving birds illustrate the adaptive value of intermediate forms?
They are derived from ancestors that fly through the air. The birds winds for use both in air and water support the assumption of adaptive intermediate forms.
How did the Great American Interchange influence the distribution of mammals?
More NA mammals went to SA than vice verse. Those immigrants underwent great diversification.
How do Hox genes generate substantial morphological change?
Regulatory genes code for transcription factors which can turn on or off coding genes. They can also code for a signaling protein which can activate a transcription factor. They generate major change through minor genetic change of regulatory genes.
