Question

Organisms such as whales and sea turtles adapted to an aquatic way of life a. will probably have homologous structures. b. will have similar adaptations but not necessarily homologous structures. c. may very well have analogous structures. d. will have the same degree of fitness. e. Both b and c are correct.

Short answer

Whales and sea turtles, being two different types of animals, have independently evolved their adaptations for aquatic lifestyles without a common ancestor specific to these adaptations. This leads to the presence of analogous structures, which serve similar functions but evolved separately in each species. They may have similar adaptations, but these do not necessarily come from homologous structures. Therefore, the correct answer is e. Both b and c are correct.

Step-by-step solution

Understand Homologous Structures

Homologous structures are organs or bones with a similar underlying structure that comes from a common ancestor but may not serve the same function. They indicate an evolutionary relationship between species.

Understand Analogous Structures

Analogous structures are structures that serve the same function in different species, but they do not share a common ancestor or similar underlying anatomy. These structures have evolved separately in each species as a result of adapting to similar environments or selective pressures.

Examine the Features of Whales and Sea Turtles

Whales (mammals) and sea turtles (reptiles) are two different types of animals that have independently evolved adaptations for their aquatic lifestyles. They do not share a recent common ancestor with one another specific to their aquatic adaptations, as their aquatic ways of life did not originate from a single ancestor. Instead, each species has evolved its adaptations specific to its own lineage.

Determine the Likely Types of Structures

Given that whales and sea turtles do not have a common ancestor for their aquatic adaptations, it is more likely that they will have analogous structures, as these structures serve similar functions in both animals, but they have evolved separately. They may have similar adaptations, such as streamlined bodies and paddling appendages, but these structures did not originate from a shared ancestor.

Evaluate Fitness

As each species has evolved its specific adaptations to suit its unique living conditions and demands, they will not necessarily have the same degree of fitness. Fitness is relative to each species and its environment, so this statement is false.

Choose the Correct Answer

Based on our analysis, we can conclude that the correct answer is: e. Both b and c are correct.

Key concepts

Homologous Structures

When unraveling the rich tapestry of life on Earth, homologous structures provide compelling evidence for evolution. These structures arise from the same embryonic tissues and have a similar arrangement or pattern, yet serve different functions in distinct species. A classic example is the forelimbs of vertebrates – the wings of bats, flippers of dolphins, and human arms have conserved skeletal structures, yet they each serve diverse purposes: flight, swimming, and manipulation, respectively.

This underlying similarity points to a common ancestor from which these varied structures have diverged. Over time, evolutionary processes such as natural selection and genetic drift act upon these structures, leading to the variety of forms we see today. However, their shared origin remains apparent through the remnants of this structure. Despite the vast difference in habitat and lifestyle between humans and bats, a closer look at our forelimbs reveals a connection spanning millions of years.

Evolutionary Biology

The foundation of evolutionary biology lies in understanding how organisms change over time and give rise to new species, a process known as speciation. Central to this domain is the concept of common descent that posits all organisms on Earth are descended from a single common ancestor. This theory is supported by various lines of evidence including fossil records, genetic information, and the distribution of organisms across the planet.

Key mechanisms driving evolutionary change include mutation, gene flow, genetic drift, and natural selection. Each plays a distinct role in altering the genetic makeup of populations. Mutations introduce new genetic material, while gene flow and genetic drift shuffle and change the frequency of existing genes within populations. Natural selection, on the other hand, works as a filter, promoting traits that enhance survival and reproductive success. Through these mechanisms, remarkable adaptations arise, suited to a variety of environments – from dry deserts to the darkest depths of the oceans.

Aquatic Adaptations

The vast and varied aquatic environments on Earth have fostered the development of specialized aquatic adaptations in numerous organisms. Characteristics such as streamlined body shapes, appendages for swimming, and physiological adaptations for osmoregulation are common among marine and freshwater species. These adaptations allow for efficient movement, respiration, and survival in aquatic habitats.

For instance, the fins of fish and the flippers of marine mammals enable swift motion through water. Moreover, organisms like dolphins have developed sophisticated echolocation systems to navigate and hunt in murky underwater environments.

Marine Reptiles

Even marine reptiles such as sea turtles have unique adaptations such as salt glands for excreting excess salt and paddle-like limbs for propulsion. Evolution has equipped each species with the tools necessary for survival in their specific niche within the vast aqueous world.