Palm Beach State College Biology Discussion

• Read and evaluate at least two of your peer’s postings and compose substantial in-depth responses for both.
• Include examples in your discussion.
• Correct grammar and spelling are required.

How to Participate:

• Once you read the discussion question, select REPLY to post your answers.

MARCOS-

Many species can reproduce either sexually or asexually. Explain what you think might be the evolutionary significance of the switch from asexual to sexual reproduction that occurs in some organisms when the environment becomes unfavorable?

“Animals produce offspring through asexual or sexual reproduction. Both methods have advantages and disadvantages. Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. A single individual can produce offspring asexually and large numbers of offspring can be produced quickly. In a stable or predictable environment, asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment. During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents. The genetic diversity of sexually produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment. Species that reproduce sexually must maintain two different types of individuals, males and females, which can limit the ability to colonize new habitats as both sexes must be present” https://opentextbc.ca/biology/chapter/24-1-reproduction-methods/#:~:text=Concepts%20of%20Biology%20%2D%201st%20Canadian%20Edition%20by%20Charles%20Molnar%20and%20Jane%20Gair%20is%20licensed%20under%20a%20Creative%20Commons%20Attribution%204.0%20International%20License%2C%20except%20where%20otherwise%20noted..

TATIANA-

Over the evolutionary course of history, many species evolved to reproduce asexually, as opposed to sexually. One example, Japanese Knotweed, is a particularly good illustration of this transfer and what factors influence the transition. One variety of this species, that invaded Europe (invasive non-native species), is “male-sterile,” so, it only reproduces asexually which reduces or removes genetic diversity (Bailey et al., 2008). Usually genetic diversity is seen as an advantage in a population, but, in the case of this species and many others, for invasive vegetative species this genetic diversity developed through reproduction by seed is not entirely essential (Bailey et al., 2008). I think there are two main points of evolutionary significance for switching to asexual reproduction. First, although there is a lack of genetic diversity in the population from crossing over DNA in sexual reproduction, there is always room for random mutation. Random mutation like that of mice changing fur color over time based on random mutation and natural selection (The Making of the Fittest: Natural Selection and Adaptation, 2011), is always a possibility when DNA is replicated, therefore, there is always a possibility for genetic variation in a population and there will always be some mutations that make the organism a better or worse fit for their environment. These mutations will lead to the evolution of the species even without sexual reproduction causing the genetic variation. Second, only one member of the population has to survive long enough to reproduce. This is advantageous for an invasive species because when the organism is in an environment where it is not native there could be very few of them. This very small population would make it very difficult to grow the population and reproduce, so, reproducing asexually will increase the likelihood that the population grows and survives.

References

Bailey, J. P., Bímová, K., & Mandák, B. (2008). Asexual spread versus sexual reproduction and evolution in Japanese Knotweed s.l. sets the stage for the “Battle of the Clones.” Biological Invasions, 11(5), 1189–1203. https://doi.org/10.1007/s10530-008-9381-4

The Making of the Fittest: Natural Selection and Adaptation. (2011, October 12). [Video]. HHMI BioInteractive. https://www.biointeractive.org/classroom-resources…

Urry, L., Cain, M., Wasserman, S., Minorsky, P., & Orr, R. (2020). Modified Mastering Biology with Pearson eText — Access Card — for Campbell Biology (18-Weeks) (12th ed.) [E-book]. Pearson.