Question

A divergence from _________ gave rise to tetrapods. a. ray-finned fishes c. cartilaginous fishes b. lizards d. lobe-finned fishes

Short answer

The correct answer is d. lobe-finned fishes.

Step-by-step solution

Understanding the question

We are being asked to determine the divergence point from which tetrapods evolved. Tetrapods are four-limbed animals, and understanding their evolutionary history will help identify the correct answer.

Analyzing the options

The options provided are types of organisms or animals that existed during the time of early tetrapod evolution. Let's briefly examine each: (a) ray-finned fishes, (b) lizards, (c) cartilaginous fishes, and (d) lobe-finned fishes.

Evaluating evolutionary context

Among the choices, lobe-finned fishes are considered one of the earliest groups that evolutionary diverged into tetrapods. These include coelacanths and lungfishes, which have limb-like fins that were precursors to true limbs in tetrapods.

Selecting the correct answer

Based on evolutionary history and anatomical similarities with early tetrapods, the most accurate answer is (d) lobe-finned fishes.

Key concepts

divergence

Divergence in evolutionary biology refers to the process by which two or more related species evolve different traits and become more distinct from each other. In the context of tetrapods, divergence is a crucial concept. It involves the branching off of tetrapods from a common ancestor, which in this case was the lobe-finned fishes.

Divergence allows species to adapt to various environments, leading to the wide diversity we see today among animals. In evolutionary terms, divergence is not a swift process but rather occurs over millions of years. During this time, species accumulate differences in their DNA and these genetic differences translate to physical and behavioral changes.

• Divergence can lead to the development of new species, an essential part of what we call adaptive radiation.
• It explains why, even though tetrapods and lobe-finned fishes share a common ancestor, they are quite different in appearance and habitat.
• Understanding divergence helps to piece together the complex puzzle of life's evolutionary history.

Tetrapods, through divergence, have become adapted to life on land, developing limbs, lungs, and other key features necessary for terrestrial existence.

lobe-finned fishes

Lobe-finned fishes, scientifically known as Sarcopterygii, are a group of fish that played a pivotal role in the evolution of tetrapods. Unlike ray-finned fishes, their fins are fleshy and lobed, supported by bone structures that resemble early terrestrial limbs. This unique anatomical design was crucial as they transitioned to land-dwelling creatures, eventually giving rise to the four-limbed animals we know today as tetrapods.

Lobe-finned fishes include species like coelacanths and lungfishes. These fishes exhibit characteristics that are key to understanding the evolutionary shift from water to land.

• Their fins contain bones similar to human limbs, providing strong evidence of a shared ancestry with tetrapods.
• Lungfish, one descendant of the lobe-finned group, have both gills and lungs, demonstrating an evolutionary adaptation for breathing both in water and on land.
• The lobe-finned fishes serve as living examples of evolutionary processes that have occurred over millions of years.

Lobe-finned fishes continue to be a subject of interest for scientists studying evolutionary history, providing critical insights into how vertebrates acquired the structures needed for life on land.

evolutionary history

Evolutionary history is the scientific study of how different species have evolved and diverged from common ancestors over time. The case of tetrapods evolving from lobe-finned fishes is a perfect example of evolutionary history in action. Scientists trace these developments through a combination of fossil records, genetic studies, and comparative anatomy.

Understanding the evolutionary history of tetrapods involves looking at a timeline spanning over hundreds of millions of years.

• The transition from aquatic lobe-finned fishes to land-dwelling tetrapods marks a significant milestone in evolutionary history.
• Features such as the development of limbs, lungs, and sensory systems adapted for land life are crucial points in this timeline.
• Each evolutionary step provides insights into how life on Earth has adapted to changing environments and ecological niches.

By studying evolutionary history, we gain valuable knowledge about biodiversity and the interconnectedness of life forms. It highlights the journey from simple organisms to the complex ecosystems present today.