We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.
In the wild species have internal and external parasites, predators and prey, organisms that rely on their droppings and the remains of their kill, organisms that share their living quarters, organisms that scavenge their dead bodies, plants that are eaten, seeds that are germinated after passing through guts.
This hypothesis of intrinsic regulation has not received clear evidence, and so the dynamics of cyclicity (e.g. population crashes) are more evidently affected by external factors e.g. predators and/or food [38] [40] Still, the "soft" hypothesis of Chitty, that genetic variation is a consequence and not a cause of population cycles, could be valid.
Thamnosophis (formerly Bibilava, see [ 74, 83]) and Dromicodryas are both diurnal and active terrestrial predators, sharing external morphological similarities [ 78].
By referring to external objects such as predators or food these signals elicit receivers' corresponding behavioural responses as if directly responding to the external cue (Seyfarth et al. 1980; Evans & Evans 2007).
The use of natural feed captured from external tanks and without predator control as performed in several fish farms, however, is discouraged since significant losses can occur of up to an entire stock.
Biofilms are resistant to external stress like antibiotics, chlorine, predators and other factors (Ryjenkov et al. 2005; Hammer and Bassler 2009).
Majestic, gargantuan birds living an idyllic existence on their island home free from predators and other external dangers.
We compared the development of external gills of salamander larvae between predator-abundant ponds and ponds with few predators.
Many fish of the Paleozoic developed external armor that protected them from predators.
