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Table 1 Phenotypic traits shifts expected to occur in insular populations as compared to their mainland relatives according to the Island Syndrome and to the RIS.

From: The blue lizard spandrel and the island syndrome

trait Island syndrome Reversed Island syndrome (RIS) Trait changes mediated by increased POMC activity (the involved MCR is indicated)
Population density high Low or inconstant -
Aggressiveness low high high, MC5R
Body size usually large small in endotherms, either small or large in ectotherms small, MC3-4Rs
Energy expenditure low high high, MC3,4R
Sexual dimorphism small high -
Development - faster, or anticipated -
Voracity* low high Either low or high, depending on the balance between MC3R and 4R
Pigmentation* irrelevant darker, but may occur in non-melanistic species as well darker, MC1R
  1. Shifts in food intake rate and pigmentation (indicated with an asterisk) are not directly predicted by the RIS hypothesis and are only true if RIS is triggered by changes in melanocortin receptors activity, and these are not polymorphic. In the last column we report the trait shifts mediated by increase in POMC expression and their relationship with RIS.