The Lotka-Volterra-equations
1. Form an introductory sentence to the figure.
2. Using all known key terms, describe the
changes in population growth for both species.
3. Discuss possible reasons for the changes in
population growth.
fig. 1
If population growth follows more or less regular patterns, they are often described in idealized graphs (fig. 2).
4. Look at fig. 2, describe the temporal interdependencies between the populations (which population increases
first, which declines or even collapses first, how do the fluctuations run, are there any cyclic regularities?)
5. Fill in the text with the key terms.
birth rate / abundance / predator (2x) /
fluctuations/ habitat/ diseases /
food shortage (2x) / hare (2x) / mean values /
pesticides / recovers / be depleted /
prey (2x) / fox/ density regulating /
wiped out / diminishing / declines /
population growth waves
If _______________________ and prey live in
the same ______________________ and the
predator mainly feeds on this _____________,
an increasing number of prey will lead to a
higher _______________________ of the predator. If the _______________________ of the prey does not
compensate the resulting loss, the number of prey will ______________________. The resulting __________
____________________ for the predator reduces its fertility and increases its vulnerability to parasites and
______________________ . The population of predators _______________________. This leads to an
increasing birth rate for the prey species and its population _______________________________ . In the long
terms this results in permanent ________________________ of both populations around their individual
____________________________ . Interestingly, in areas where the fox has been ________________________,
the population of hares still follows characteristic __________________________________________.
Responsible for this are other ___________________________ factors e.g. _________________________.
Therefore it can be concluded that the _________________population does not control the hare population.
The later rather controls itself and the population of its ___________________. In areas where both
populations are strongly decreased e.g. due to the application of _____________________, the population of
________________ will recover quicker as the shortage of food (due to missing prey) has an additional
____________________________ effect on the foxes.
birth rate / abundance / predator (2) / fluctuations/ habitat/ diseases / food shortage / hare-/
hares/ mean values / pesticides / fox / recovers / be depleted / prey / density regulating / wiped
out / diminishing / declines /
population growth waves
If _____predator__________________ and prey live in the same ____habitat__________________ and the
predator mainly feeds on this ___prey____________________, an increasing number of prey will lead to a
higher ___________abundance____________ of the predator. If the __birth rate_____________________ of
the prey does not compensate the resulting loss, the number of prey will _be__depleted___________________.
The resulting ____food shortage________ for the predator reduces its fertility and increases its vulnerability
to parasites and _________diseases_____________ . The population of the predator
______________declines_________. This leads to an increasing natality for the prey species and its population
_____________recovers__________________ . In the long terms this results in permanent
______fluctuations____________________ of both populations around their individual ___mean values
_________________________ . Interestingly, in areas where the fox has been _______wiped out
____________________, the population of hares still follows characteristic ______
population growth
waves ______________. Responsible for this are other ____ density regulating _______________________
factors e.g. __food shortage__________________. Therefore it can be concluded that the
_____fox_________population does not control the hare population. The later controls itself and the
population of its ___predator_________________. In areas where both populations are strongly decreased e.g.
due to the application of______pesticides_____________________, the population of ______hares__________
will recover quicker as the shortage of food (due to missing prey) has an additional __diminishing_______
effect on the foxes.
Bewohnen ______Räuber_________ und Beute den gleichen _________Lebensraum_________ und ernährt
sich der Räuber primär von dieser ________Beute_______________, so führt eine Zunahme der Beutetiere
auch zu einer ________Vermehrung_______________ der Räuber. Gleicht die
_____Vermehrungsrate________ der Beuteart diese Verluste nicht mehr aus, so wird die Anzahl Beute
______dezimiert_________________ . Der entstehenden ______Nahrungsmangel_________________ beim
Räuber verringert u.a. dessen Fruchtbarkeit und erhöht die Anfälligkeit für Parasiten und
______Krankheiten_________________. Die Räuberpopulation _____verringert__________________ sich.
Dadurch kann die Beuteart sich wieder vermehren und die Population __________erholt_____________ sich.
Es entstehen fortgesetzte __Populationswellen________________ zwischen Räuber und Beute. In Gebieten, in
denen der Fuchs _____ausgerottet__________________ wurde, zeigen die Hasen dennoch die
charakteristischen Populationswellen. Verantwortlich sind dann andere _dichteregulierende Faktoren______
wie z. B. Nahrungsmangel. Der ____Fuchs___________________ kontrolliert also nicht die __________Hasenpopulation, sondern diese kontrolliert sich selbst und die Fuchspopulation. In Gebieten, in denen beide
Populationen durch Anwendung von _____Giften__________________ dezimiert wurden, erholt sich die
Population der ________Hasen_______________ schneller, da durch den zunächst auftretenden
Nahrungsmangel (fehlenden Beute) die ___Füchse____________________ zusätzlich dezimiert wurden.