8.7 Disruptions to Ecosystems

Unit 8.7: Disruptions to Ecosystems

Disruptions to ecosystems can lead to significant consequences for the species within them, often driving evolutionary changes. Let’s explore how different disruptions affect ecosystems, from natural changes to human influences.

Evolution and Environmental Changes

Disruptions to ecosystems can be a catalyst for the process of evolution. When environments change, some organisms may gain selective advantages through specific adaptations, which enable them to survive and reproduce more successfully compared to others.

Adaptations are heritable genetic variations that enhance an organism’s fitness—its ability to survive and reproduce. Increased fitness allows these organisms to pass their genes on to their offspring, contributing to the process of natural selection. Natural selection occurs when certain heritable variations induce differential reproductive success, favoring those with traits best suited for survival.

While mutations can introduce new alleles that provide fitness advantages, it is important to remember that mutations are random and are not directly driven by environmental pressures.

Competition and Invasive Species

Disruptions to ecosystems often increase competition, which can shift population sizes. A decline in a particular resource may result in increased competition both within a species (intraspecific) and between different species (interspecific). Those species that are better at acquiring resources will have higher chances of survival and reproduction.

The introduction of invasive species is a common disruption that often has negative effects. Invasive species are introduced, either intentionally or unintentionally, into an environment where they have no natural predators or competition to regulate their population. These species can exploit new ecological niches and disrupt the balance of existing ecosystems.

One well-known example is the introduction of the brown tree snake to Guam. The brown tree snake arrived from the South Pacific as a stowaway in ship cargo. With no natural predators in Guam, the snake population exploded, leading to the extinction of many of Guam’s native bird species and the decline of small mammal populations. 🦜

Natural and Human-Caused Disruptions

Ecosystem disruptions can be either natural or anthropogenic (caused by human activity). Unfortunately, human influences have been some of the most damaging. Activities like deforestation, pollution, the spread of invasive species, and contributions to climate change have led to habitat destruction, species extinction, and widespread ecological imbalances. Organisms that cannot quickly adapt to these changes are at risk of extinction.

Natural disruptions can also cause significant changes within ecosystems. Events like flooding, forest fires, and earthquakes alter habitats and disturb the balance of ecosystems. Many of these natural occurrences are becoming more frequent and intense due to human impact.

Whether natural or human-caused, ecosystem disruptions put immense pressure on the organisms living there, affecting their ability to survive and thrive.