Animal cognition meets ecosystem ecology: the impact of cognition on seed dispersal

Soldati, Francesca (2015) Animal cognition meets ecosystem ecology: the impact of cognition on seed dispersal. PhD thesis, University of Lincoln.

23685 Soldati, Francesca - Biology - August 2015.pdf
23685 Soldati, Francesca - Biology - August 2015.pdf - Whole Document
Available under License Creative Commons Attribution.

Item Type:Thesis (PhD)
Item Status:Live Archive


Seed dispersal by endozoochory is important for the maintenance of plant
populations and biodiversity. As a result, understanding the impact that
frugivores’ activities have on seed dispersal is essential in order to better
understand plant population dynamics. One factor that is known to affect an
animal’s behaviour, yet has received little attention in this context, is animal
cognition i.e. whether the information animals learn and remember affects where
they access fruit and deposit seeds. Therefore, the aim of this thesis was to
address how animal learning and memory affects the seed dispersal process, using
two key approaches – experimental tests of frugivore cognition, and a model
paramaterised to examine the consequences of different cognitive abilities on seed
dispersal. Three questions were investigated:
(1) The “where?” - whether the ability of frugivores to relocate previously
visited food sources impacts upon their movements and, as a consequence, on
plants’ seed shadows. The spatial learning and memory of red-footed tortoises
was tested using an egocentric task. Tortoises were able to navigate efficiently in
the environment, and remembered the spatial location of food for at least two
months. A seed dispersal model designed to test whether frugivores with different
spatial memory skills differently affect plants’ seed shadow, suggested that
animals with long spatial memory relocate more efficiently food sources than
animals’ with shorter memory. As a consequence, animals with longer memory
survived longer, dispersed a bigger amount of seeds, and moved less at random
around the environment, all of which lead to different spatial distribution of
deposited seeds.
(2) The “What?” - whether seed dispersers’ discriminatory skills and
memory affects their choice of fruit. Tortoises’ ability to discriminate between
quantity and quality of food was tested. They were able to successfully
discriminate between the visual cues indicating different types of food and
remembered the task for at least 18 months. A seed dispersal model designed to
investigate whether the memory of quality and quantity of food affects seed
dispersal showed that the ability to discriminate between the features of fruits and,
in particular, the memory of those, allows animals to base their foraging decision
on previous learned experiences, significantly increasing the amount of seed
dispersed from the preferred fruit.
(3) The “When?” - whether the ability to anticipate events, such as food
availability, and learn about plants fruiting cycles affects plants’ seed shadows.
Tortoises’ anticipatory skills were tested on a 24 h cycle. They were able to
anticipate food delivery, showing an increase in activity immediately prior the
scheduled food delivery time. A seed dispersal model designed to test the impact
of timing on dispersal showed that animals that are able to anticipate cycles equal
to or longer than plants’ fruiting cycle readily relocate food, survive longer and
disperse more seeds than those with memory that doesn’t last as long as a fruiting
Finally, I present a model parameterised with red-footed tortoise cognitive
data, with the aim to test one of the characteristics that makes tortoises unusual as
seed dispersal vectors: the use of gaps in the forest. The results suggest that the
active use of gaps enhances the probability of seed deposition in gaps and
deforested areas, making tortoises a possible reforestation “tool”.
I have demonstrated that the study of frugivores’ cognition can help to
build more reliable predictions of seed dispersal by endozoochory: cognition is
probably the most effective way to understand and predict an animal’s choices
and movements around the environment. Future research should incorporate
cognition in the study seed dispersal via endozoochory to have more reliable
predictions of plant dynamics.

Keywords:Animal cognition, Seed dispersal
Divisions:College of Science > School of Life Sciences
ID Code:23685
Deposited On:24 Aug 2016 11:55

Repository Staff Only: item control page