Extinction

Question 1

Types of extinction

Answer 1

Contemporary
-Local extinction - loss of population from a particular area
-Species extinction - the death of all members of a species

Geological
-Background extinction - the sum of all normal species terminations during a defined time interval
-Extinction events - times when many species go extinct for a shared reason, typically regional rather than global in scale
-Mass extinction events - times of geologically rapid global disappearance of much of life, when many species of wide ecological range died out worldwide

Question 2

Why do species go extinct?

Answer 2

Red Queen hypothesis
-Proposes that species go extinct because of their inability to keep up with the ever-changing biotic and abiotic factors in their environment. In other words, species must constantly evolve and adapt to stay competitive and survive in their environment. If a species fails to adapt, it may go extinct

Court Jester hypothesis
-Suggests that species are more likely to go extinct due to random events or external factors, such as catastrophic events, diseases, or changes in climate or geology. In this theory, extinction is not necessarily caused by a lack of adaptation, but rather by chance events that can wipe out entire populations or species

Question 3

Species selection

Answer 3

Species selection is the idea that some species have characteristics that make them more likely to speciate or less likely to go extinct

Requirements of species selection
-Variation - species must differ in the focal trait
-Heritability - the trait must be inherited
-Differential success - the trait must confer different probabilities of speciation/extinction

Broad sense species selection
-Aggregate traits e.g. body size

Strict sense species selection
-Emergent traits e.g. range size

Emergent traits arise from complex interactions between simple components, while aggregate traits are simply the sum of individual traits