The most common causes for biodiversity loss are habitat loss, pollution, over-exploitation of natural resources, introduction of new or exotic species, and climate change. These factors can be threatening, which could even lead to the extinction of species. This is how you explain the causes for the loss of biodiversity.
Habitat Destruction
Habitat is the site where the species naturally occurs. This could be a wetland, forest, or any other place that can support the species. When this natural habitat is no longer favourable for the species, they can be displaced or destroyed. This is called habitat destruction.Â
- Habitat degradation is the decline of the species-specific quality of habitat, which causes reduced survival or reproductive rate of the population.Â
- Habitat fragmentation is a break in the continuous habitat.Â
Introduction of Exotic Species
An exotic species introduced into a habitat can cause changes in the ecosystem. These exotic species may show characteristics like rapid growth, quicker reproduction, and higher ability for dispersal, the ability to adapt physiologically to the new environment, and can also survive on different food types (in the case of animals).Â
Such aggressive growth of the species can harm the ecosystem and lead to the extinction of native species.
Over-Exploitation
Over-exploitation refers to human activities like hunting, farming, fishing, etc, that can remove the biomass of an individual or a population at an alarmingly larger rate. It causes population size reduction, making them vulnerable. It may be caused by incidental exploitation by catching one species accidentally while targeting another.
Climate Change
Continuing climate change affects the adaptability of species, leading to a reduction in their population and later to their extinction. Frequent rainfall, extended winter, or higher heat can all cause damage to individuals.Â
Pollution
Pollution of the ecosystem in the form og air pollution, water pollution, soil pollution, etc, can have a negative effect on species and can affect their survivability.
Population Regulation in Ecology and Its Significance
Population regulation is the ecological process that helps control or limit the growth of populations by affecting the birth and death rates. Various mechanisms help in regulating the population. The factors that enable such mechanisms or limit the birth or death rate can be density-dependent or density-independent.
Density-Dependent Factors
Such limiting factors are biotic. They also include diseases, predation competition for resources, etc, that affect as a function of population density. For example, the growing population of one species causes competition among species, which either causes a reduced birth rate or an increased death rate. Both these scenarios cause a decline in reproductive rate and population density. An increase in prey species results in higher predation rates.
Density-dependent limiting factors generally cause populations to reach a maximum level known as their carrying capacity. At its carrying capacity, the population size becomes stable and is called logistic growth. A stable population continues to grow larger at an increased pace known as exponential growth.
Density-dependent factors can affect either negatively or positively. When it causes a reduced birth rate or increased death rate, the impact is negative feedback. When these factors cause an increase in population size, it is called a positive feedback or Allee effect.
Populations that experience density-dependent limiting factors are often insatiable, and experience cycles of growth followed by a reduction in size in a pattern known as cyclical oscillations. Predation is an example of cyclical oscillation involving multiple species.Â
Density-Independent Factors
Density-independent factors are abiotic, such as natural disasters that affect a fraction of the population, no matter how small or large the population. These factors are not dependent on the population’s size. But they can be more catastrophic to a small population of species that are in a limited geographic range.
Top-Down Population Regulation
Top-down population regulation is where the species from a higher trophic level controls the population of a species in a lower trophic level. For example, predators regulate the population of their prey species at a lower level. Such population regulation is known as “predator-controlled” regulation.
Bottom-Up Population Regulation
Bottom-up population regulation depends on the resources of the ecosystem. The species in higher trophic levels depend on the species of lower trophic levels. Due to this, an absence or reduction in the lower-level population affects the higher levels.
References
- https://www.studysmarter.co.uk/explanations/biology/ecology/population-regulation/
- Shukla, R.S. and Chandel, P.S. (2001) Plant Ecology. S. Chand and Company Ltd., New Delhi.
- Verma, P.S., Agarwal, V.K. (1999). Cell Biology, Genetics, Molecular Biology, Evolution, and Ecology. New Delhi: S.Chand Co.(Pvt) Ltd.
