Natural selection is nature’s way of keeping the best fit-to-live things alive, and so on continue to the next generations.
For example, if a rabbit has a limp, it is bound to be out run and eaten by a predator relatively early in its life (unless it is extremely lucky.) Because of this, it is unable to reproduce, and there genes that it contained to have its limp are unable to spread through inheritance. Natural selection goes both ways. For example, if a hawk has very god vision, it will be able to scope out its prey easily, so it will thrive. Therefore, when it produces offspring of its own, its trait of good eyesight will pass on to its offspring.
So, as enough time goes on, the bad traits will be weeded out and the good ones will remain.
The correct answer is: The synaptonemal complex.
Non-sister chromatids are chromatids from two homologous chromosomes. In prophase I of meiosis two homologous chromosomes pair and this pairing is called synapsis. This allows possible crossing over to occur. Two non-sister chromatids are connected in synapsis by a protein-RNA complex called the synaptonemal complex.
Crossing-over or the physical exchange of chromosome parts might occur and bring to genetic recombination. The sites of crossing-over between nonsister chromatids and are called chiasmata.
Answer:
sympatric speciation
Explanation:
Different sympatric species have the same closest ancestor and live in the same area but inhabiting different niches.
The steps for sympatric speciation are:
- An ancestral species inhabit a geographic area.
- With time, different populations of the same species occupy different niches or microhabitats in this general area.
- As the microhabitats are different, they have different environmental pressures that are acting on each population.
- These pressures lead to the origin of differences between groups, which need to adapt to each environment
- Each population suffers genetic changes due to environmental conditions. These changes are inheritable.
- With time, these differences drive to the final complete divergence of populations, becoming different species and reproductively isolated.
In sympatric speciation, the interruption of genetic flow must be fast, and there must be differences in niches so no species can compete and displace the other species. <em>Speciation occurs in the same distribution area of the original species</em>. The new species originate in a place with no physical barriers but different environmental pressures.
In the exposed example,
- <em>The introduced Cichlid fishes 200 years ago</em> → Original species and the common ancestor between the new derivated species
- <em>The lake</em> → general geographic area
- <em>The main lake and the streams</em> → Microhabitats or niches with different pressures each
- <em>The groups are splitting into two genetically and physically different types of fishes. They do not mate. There is no genetic flow between groups.</em> → Speciation process.
Ureter is a tube that carries excreted urine to the bladder..
