12 Questions
Quels sont les facteurs qui influent sur la croissance d'une population, mais ne dépendent pas de la taille ou de la densité de la population?
Facteurs abiotiques denses-indépendants
Qu'est-ce qui affecte la qualité des nutriments dans un environnement?
Les polluants dans l'environnement
Quels sont les deux principaux types de facteurs qui limitent la croissance des populations?
Facteurs de densité dépendants et facteurs de densité indépendants
Quel est le résultat de l'interaction entre les facteurs denses-dépendants et denses-indépendants?
Une oscillation cyclique de la population
Quel est l'effet d'une densité de population élevée sur la croissance de la population?
Elle augmente la compétition pour les ressources
Qu'est-ce que la capacité de charge d'un habitat?
Le nombre maximum d'individus que le habitat peut supporter
Quel est un exemple de facteur de densité dépendant qui affecte la croissance de la population?
La disponibilité de nourriture
Qu'est-ce qui limiterait la croissance d'une population si elle atteint sa capacité de charge?
Les deux
Quel est le résultat de la compétition pour les ressources sur la croissance de la population?
Une diminution de la vitesse de croissance de la population
Quel est un caractère commun aux facteurs de densité indépendants?
Ils sont indépendants de la densité de la population
Quel est le résultat final de l'interaction entre les facteurs denses-dépendants et denses-indépendants?
Une régulation de la taille de la population
Quel est le rôle des facteurs de limitation de la population dans l'environnement naturel?
Ils maintiennent la population à une taille spécifique
Study Notes
Factors That Do Not Change Populations
Populations, in nature, grow and thrive under certain conditions, but they also face various limitations that prevent their uncontrolled growth. These limitations are factors that, when present, do not allow populations to change, either by stopping their growth or by keeping them at a specific size. These factors can be divided into two main categories: density-dependent and density-independent factors.
Density-dependent Factors
Density-dependent factors are those that affect population growth directly in relation to the population's size and density. They cause a population's per capita growth rate to change with increasing population density. For example, in the case of a population of organisms with access to a fixed, constant amount of food, the limited amount of food will be plenty when the population is small. However, as the population grows, the food will become scarce, leading to a decrease in population growth rate.
Another example of density-dependent limitation is competition for resources. As a population grows, the competition for resources such as food, water, and space intensifies. This competition can lead to a decrease in the survival rate of individuals, which in turn reduces the population's growth rate.
Density-independent Factors
Density-independent factors are those that affect population growth independent of population density. They are not influenced by changes in population size or density. These factors can be biotic or abiotic.
Abiotic density-independent factors include environmental stressors and catastrophes. For example, natural disasters such as forest fires, hurricanes, and monsoons can impact population growth. They do not depend on the size or density of the population, but rather on the environmental conditions.
Biotic density-independent factors include food or nutrient limitation, pollutants in the environment, and climate extremes. For instance, the quality of nutrients in an environment affects the ability of an organism to survive, grow, and reproduce. The lower the quality of the nutrients, the higher the environmental stress. Pollutants such as pesticides and endocrine disrupting toxins can also limit population growth by affecting the growth rates of individuals or even driving species to extinction.
Interaction of Density-dependent and Density-independent Factors
In reality, populations are subject to the combined effect of both density-dependent and density-independent factors. These factors can interact in complex ways to produce various patterns of population growth. Some populations show cyclical oscillations, in which population size changes predictably in a cycle. This can be due to the combined influence of density-dependent and density-independent factors.
Carrying Capacity
The interaction of density-dependent and density-independent factors determines a habitat's carrying capacity, which is the maximum size of the population it can support. When a population reaches this carrying capacity, it will stop growing and may even begin to decline.
In conclusion, population growth is not an infinite process. There are factors that limit population sizes, both in terms of density-dependent and density-independent factors. These factors work together to regulate population size and growth, ensuring that populations remain within the bounds of their carrying capacity.
Découvrez les facteurs qui empêchent les populations de croître de manière incontrôlée, notamment les facteurs denses-dépendants et denses-indépendants, et leur interaction pour déterminer la capacité de charge d'un habitat. Ce quiz vous aidera à comprendre les mécanismes qui régissent la croissance des populations dans la nature.
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