Uploaded by Karin Schulz

AB Lotka-Volterra1

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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.

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