Question

A fire devastates all trees in a wide swath of forest. Populations of a species of tree-dwelling frog on either side of the burned area diverge to become separate species. This is an example of ______.

Short answer

Allopatric speciation.

Step-by-step solution

Understanding the concept

To solve the problem, we need to understand the key concepts involved. The problem describes a situation where a natural disaster (fire) separates two populations of the same species into distinct groups. Over time, these groups evolve separately on either side of the burned area.

Defining the terms

The problem involves concepts of evolution and speciation. When two populations of the same species are separated by a physical barrier (like a burned area), the populations evolve independently. This process can eventually lead to the development of distinct species.

Identifying the type of speciation

The problem describes geographic isolation due to the burned area separating the populations. This type of speciation is known as allopatric speciation, where new species form in different geographical locations due to physical separation.

Answering the exercise

Based on the identified type of speciation, we conclude that the fire-induced separation of frog populations leading to the development of separate species is an example of allopatric speciation.

Key concepts

Geographic Isolation

When a fire sweeps through a forest, it can create a physical barrier like a burned area where previous flora once existed. This division is a form of geographic isolation. Geographic isolation occurs when physical barriers such as mountains, rivers, or fires separate populations of the same species.
In the case of our tree-dwelling frogs, the fire effectively splits their habitat, rendering two isolated pockets of forest. This prevents the frogs on either side from interacting or breeding with each other.
This process is significant because it interrupts the gene flow between these separated groups, which is crucial for maintaining genetic diversity within a population. Over time, as these isolated groups continue reproducing separately, they might start to experience different environmental pressures or develop unique mutations. This sets the stage for the other processes we'll discuss next.

Speciation

Speciation is the process by which ordinary populations diverge to form new species. Geographic isolation plays a vital role in this, particularly in a form called allopatric speciation. Allopatric speciation is exactly what happens when separated populations, like our frog populations, evolve independently.
With the frogs unable to cross the burned area, the genetic exchange halts, preventing them from sharing new genetic traits. As time passes, the separate populations adapt to their specific environments. This can include developing new behaviors or physical traits, which are beneficial in their distinct ecological niches.
These differences accumulate over many generations, eventually reaching a point where even if the geographical barrier is removed, the two populations may no longer interbreed successfully. This marks the point where speciation has occurred; they have transformed into two separate species.

Evolution

Evolution is the fundamental process that drives the diversity and complexity of life on Earth. At its core, evolution involves changes in genetic traits in a population over many generations.
The frogs from our scenario offer a vivid glimpse into how evolution can proceed in isolated populations. Each group confronts unique challenges and opportunities within their part of the forest. These differences shape their evolutionary path, selecting for traits that improve survival and reproduction in their specific conditions.
Over time, while mutations arise and natural selection operates, the two frog groups progressively drift apart genetically. Evolutionary processes enable them to adjust and survive in their distinct environments, further emphasizing the complex and adaptable nature of life. This divergence exemplifies how life can change form and flourish despite significant environmental upheavals.