Question

$$A(n)$$ ______ species is one that arrives early in succession. a. keystone b. pioneer c. commensal d. exotic

Short answer

The correct answer is b. pioneer.

Step-by-step solution

Understand Succession

Ecological succession is a process by which ecosystems change and develop over time. The two main types are primary succession, which starts with no life on a barren landscape, and secondary succession, which occurs in areas where a community has been disrupted.

Define Key Terms

Identify terms related to species involved in succession: - Pioneer species: The first to colonize an area during ecological succession. - Keystone species: Play a critical role in maintaining the structure of an ecosystem. - Commensal species: Derive a benefit from another species but do not harm or benefit the other. - Exotic species: Also known as invasive species, they are not native to the area.

Match Definitions to Answer Options

Compare the definitions with the answer options: - Pioneer: First to arrive in succession. - Keystone: Not defined by arrival timing. - Commensal: Not specifically related to succession. - Exotic: Not necessarily related to succession timing.

Choose the Correct Answer

Given that pioneer species are characterized by their early arrival in an uncolonized area, the correct term that fits the definition is "pioneer species."

Key concepts

Pioneer Species

Pioneer species are nature's trailblazers, paving the way for the ecological succession process. These species are the first to colonize barren or disrupted environments. Imagine a landscape that's been swept clean by a volcanic eruption or landslide. In such places, where no life currently exists, pioneer species are the initial settlers.
These species are adapted to the harsh conditions prevalent in such environments. They often have traits that allow them to:

• Survive with minimal resources like water and nutrients.
• Persist in extreme temperatures or conditions.
• Grow quickly and reproduce fast.

Their role is crucial as they start to modify the environment, making it more hospitable for other, less hardy species.
By doing so, they help to kickstart the process of ecological succession. Pioneer species are like the first stones laid in a pathway, setting the stage for more complex communities of plants and animals to develop over time.

Primary Succession

Primary succession is the ecological cleanup crew for barren landscapes, starting the cycle of life in areas previously devoid of any biotic community. This type of succession begins in environments where no soil or life exists, such as new volcanic islands, retreating glaciers, or sand dunes.
The first stage involves pioneer species, like lichen and mosses, that can adhere to rock surfaces. These organisms perform a vital role:

• Break down rocks, gradually turning them into soil.
• Enrich the environment with nutrients as they die and decompose.

As they do this, they create conditions suitable for further life to flourish. Once these conditions improve, other species such as grasses and later shrubs can establish.
Primary succession takes a significant amount of time since it essentially builds an ecosystem from scratch. Over many years, this process can transform a barren landscape into a flourishing ecosystem with a rich diversity of plant and animal life.

Secondary Succession

Think of secondary succession as a nature-driven renovation project, which occurs in areas where an existing community has been disturbed but the soil remains. This type usually happens after events like wildfires, hurricanes, or human activities that clear a forest.
Since the soil already contains seeds and microorganisms, secondary succession proceeds more rapidly than primary succession. The first colonizers in secondary succession are often faster-growing species such as grasses and small plants.

• These plants take advantage of the sunlight that reaches the ground in the absence of taller trees.
• They stabilize the soil and begin to replenish nutrients.

As these pioneer species stabilize the environment, they allow more complex plants, like shrubs and trees, to take over.
Within a relatively shorter timeframe compared to primary succession, secondary succession can rebuild a damaged ecosystem into a rich biological community. This process highlights the resilient capacity of nature to recover and bounce back often in just a few decades.