Question

Assertion: Members of a species breed only with others of the same species. Reason: In some cases, members of different species may also breed, producing sterile or fertile offspring.

Short answer

The reason statement does not refute the assertion but rather extends it by providing an exception. Hence, while the assertion holds as a general rule, the reason provides a possible exception in 'some cases'.

Step-by-step solution

Understanding the assertion

The first statement given is the assertion, which says, 'Members of a species breed only with others of the same species.' It means a certain species generally reproduces or mates with the members of the same species. Analyzing this assertion, it seems correct because usually, different species have different mating behaviors, signals, and body structures, which makes it more likely for members of the same species to breed among themselves.

Understanding the reason

The reason given is, 'In some cases, members of different species may also breed, producing sterile or fertile offspring.' This states that mating is possible between different species occasionally, and the resulting offspring might either be sterile or fertile. Now, this reason appears to contradict the assertion at first because it says that breeding can happen between different species, but it does not necessarily refute the main assertion which stated breeding generally happens within same species.

Relating the assertion and the reason

Now that the assertion and the reason are understood, they have to be related. It is found that the reason does not dispute the assertion but adds an extra point mentioning 'some cases' where members of different species can breed as well. This means that while typically the members of the same species breed among themselves, there can be exceptions in which members from different species can also breed to produce either sterile or fertile offspring.

Key concepts

Species Breeding Behaviors

Understanding species breeding behaviors is essential for grasping how reproduction takes place in the animal kingdom. Breeding behaviors are complex actions through which organisms attract and select mates, ultimately ensuring the continuation of their species. These behaviors are often specific to a species and include a variety of rituals, such as vocalizations, displays of physical prowess or beauty, and the release of pheromones.

For instance, the vibrant dance of a peacock is meant to attract peahens, while the song of a bird might be tailored to woo a mate from the same species. The specificity of these actions ensures that breeding typically occurs within the same species, as they have evolved over time to respond to particular signals and cues that are often unrecognizable or unattractive to other species.

However, these breeding behaviors also reflect the species' ability to adapt and can sometimes lead to interspecies interactions. Understanding this concept can significantly improve the student's grasp of species reproduction, as detailed in the textbook.

Inter-species Breeding

Inter-species breeding, also known as hybridization, is a less common but noteworthy aspect of animal reproduction. This occurs when members from different species mate, generally leading to hybrid offspring. A classic example of this is the mule, produced by breeding a male donkey with a female horse. These incidents can happen both in natural settings and due to human intervention.

However, breeding across species is generally less successful due to differences in mating behaviors, genetics, and reproductive structures. When it does occur, it can provide fascinating insights into the flexibility and limitations of genetic compatibility. The rarity of such events underscores the myriad of obstacles to successful inter-species reproduction - from different breeding seasons and behaviors to the inability of sperm and egg from different species to fuse and form viable offspring.

While students might be intrigued by the possibility of inter-species breeding, it's important to highlight its rare occurrence and the biological complexities that often prevent it from happening successfully, as the textbook solution shows.

Sterile and Fertile Offspring

The outcome of breeding, whether within a species or between different species, results in either sterile or fertile offspring. Sterility in hybrid offspring, such as the aforementioned mule, is common due to genetic incompatibilities that prevent the chromosomes from pairing properly during meiosis. This means that, although the hybrid animal may live a healthy life, it cannot reproduce.

If the offspring is fertile, it means that the genetic information from both parent species enables viable gametes to be produced, thus giving the offspring the ability to further reproduce. Fertility is a strong indication of the close genetic relationship between the parent species. For example, some hybrid species of canids (such as wolves and coyotes) have been known to produce fertile offspring.

Understanding the distinction between sterile and fertile offspring not only increases comprehension of genetic compatibility between species but also has implications for biodiversity and the management of species and ecosystems, making it a crucial point of study in the context of Species Reproduction NEET.