Herd size in large herbivores: encoded in the individual or emergent?
In large mammalian herbivores, the increase of group size with habitat openness was first assumed to be an adaptive response, encoded in the individual. However, it could, alternatively, be an emergent property: if groups were nonpermanent units, often fusing and splitting up, then any increase of the distance at which animals perceive one another could increase the rate of group fusion and thus mean group size. Dynamical models and empirical data support this second hypothesis. This is not to say that adaptive modifications of mean herd size cannot occur. However, this changes the way in which we can envisage the history of gregariousness in large herbivores during the Tertiary.
Gerard
Jean-François
JF
Institut de Recherche sur les Grands Mammifères, INRA, BP 27, 31326 Castanet Tolosan Cedex, France. jfgerard@toulouse.inra.fr
Bideau
Eric
E
Maublanc
Marie-Line
ML
Loisel
Patrice
P
Marchal
Carole
C
D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D003670:Deer; D017753:Ecosystem; D008954:Models, Biological; D011156:Population Density