Bat time stories [Elektronische Ressource] : decision-making in spatio-temporally predictable environments / vorgelegt von Ulf Tölch

Ulf Tölch

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2006
• Nombre de lectures: 7
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

1. Gutachter: P rof. D r. Y ork W inter
2. Gutachter: P rof. D r. Ba rt K empenaers
Tag de r m ündlichen P rüfung: 31.03.2006Time is the measurable unit of movement concerning a before
and an after.
Aristotle
If you can look into the seeds of time,
And say which grain will grow and which will not,
Speak then to me.
Act I, Sc. III
Banquo in
'Macbeth' by
William
Shakespeare
There is surely no greater wisdom, than well to time the
beginnings, and onsets, of things.
Francis Bacon Table of Contents
S ummary............................................................................................................................................ 5
Cha pter 1 General introduction............................................................................................................ 9
Cogni tion a nd E volution ............................................................................................................... 10
Foraging on fl oral ne ctar 11
Experimental subjects.................................................................................................................... 12
A im of t his study............................................................................................................................ 12
L iterature........................................................................................................................................ 14
Cha pter 2 Density de pendence of s patial cue fa cilitated fora ging by a fl ower ba t............................ 17
A bstract.......................................................................................................................................... 17
Int roduction.................................................................................................................................... 18
M aterials and M ethods................................................................................................................... 20
Re sults............................................................................................................................................ 23
Discussion...................................................................................................................................... 28
L iterature 30
Cha pter 3 Foraging on ne ctar: A fl ower vi siting ba ts ability t o pe rceive di fferences in ne ctar vol ume 33
A bstract.......................................................................................................................................... 33
Int roduction 34
M aterials and M ethods 35
Re sults 37
Discussion 39
L iterature........................................................................................................................................ 40
Cha pter 4 Investigating t he impact of e cology upon t he timing a bility i n a nimals.......................... 43
A bstract 43
Int roduction.................................................................................................................................... 44
M aterials and m ethods................................................................................................................... 45
Re sults............................................................................................................................................ 47
Discussion...................................................................................................................................... 50
L iterature 53
Cha pter 5 Cogni tive abilities in c omplex e nvironments: Flower-vi siting ba ts and t he assessment of
nectar produc tion ra tes. ............................................................................................. 55
A bstract.......................................................................................................................................... 55
Int roduction 56
M aterials and M ethods................................................................................................................... 58
Theoretical m odels......................................................................................................................... 61
Re sults............................................................................................................................................ 66
Discussion 72
L iterature........................................................................................................................................ 76
Cha pter 6 Risk s ensitivity t o food a mounts in ne ctar-fe eding ba ts: a be havioural m echanism for t he
ideal fre e di stribution.................................................................................................. 79
A bstract.......................................................................................................................................... 79
Int roduction.................................................................................................................................... 80
M aterials and M ethods................................................................................................................... 81
Re sults 83
Discussion...................................................................................................................................... 84
L iterature........................................................................................................................................ 88
3Cha pter 7 General Discussion............................................................................................................ 91
M echanisms of t iming................................................................................................................... 93
Cogni tion a nd e cology 94
Perspectives for fut ure studies....................................................................................................... 95
L iterature........................................................................................................................................ 96
A cknowledgements............................................................................................................................ 99
Illustration Inde x.............................................................................................................................. 101
Inde x of T ables................................................................................................................................. 102
A ppendices....................................................................................................................................... 103
4SummarySummary
SINCE ENVIRONM ENTS UNDERL IE a constant change, animals ne ed t o ke ep t rack of t hese
changes by ga thering i nformation a nd by us ing t his information t o m ake de cisions. During t he
course of e volution, c ognitive abilities, information proc essing s kills, ha ve evolved i n m any s pecies
to c ope w ith t he re quirements of di verse ha bitats.
In this study I i nvestigated t he cognitive abilities involved i n t he fora ging on re newable
resources. Examples for s uch re sources include ne ctar, frui ts, or fol iage. Re newable re sources
possess two qua lities that can be us ed by a n a nimal to opt imise its fora ging be haviour; fi rst, onc e an
animal di scovers a location w here such a re source can be found, i t is profi table to re turn t o t his
location l ater s ince m ost re newable re sources are not m obile. Second, t here is oft en a temporal
pattern unde rlying t he re newal proc ess so t hat such a re source re news itself w ith a m ore or l ess
constant produc tion ra te. Thus, it w ould be a clear a dvantage if a n a nimal w ere able to re member
the location a nd t o e stimate the produc tion ra te of a re source. To re member t he location of a
resource can s ave time and e nergy for s earching, a nd t he ability t o a ssess the produc tion ra te w ould
allow an a nimal to t ime its re turn s o t hat the di fference be tween t he energy t hat is ne eded t o t ravel
to t he re source and t he energy ga ined a t the re source is pos itive.
I explored t hese pos sibilities in a fl ower-vi siting ba t, Glossophaga s oricina, which fora ges
mainly on fl oral ne ctar. This species w ill thus allow for t he study of c ognitive specialisations in t he
domains of s patial m emory a nd i nterval timing. T his study a imed a t the fol lowing que stions:
1. W hat spatial information w ill these ba ts us e to re locate already vi sited fl owers and
how is this information e ncoded?
2. Ca n ba ts us e temporal and qua litative information t hat can be obt ained w hen vi siting
a fl ower t o t ime their re visits?
3. W hat implications arise from these re sults for t he dyna mics on a popul ation l evel?
W hen re locating fl owers, ba ts ha ve several spatial stimuli available. However, some of t hese
stimuli are spatially di ssociated from the fl ower l ike conspicuous bra nches or l eaves. W hen t he
spatial contiguity be tween a stimulus and a re sponse location i s not gi ven, it is di fficult or e ven
impossible to form associations for s ome species. However, in t he case of fl ower-vi siting ba ts, it
could be of a dvantage to us e these stimuli in t he re location proc ess. In chapter 2, I e xplored t his
possibility by provi ding t he ba ts w ith a dditional cu