Gracie Faver Evolution Class Blog

Advantages of Sexual Reproduction      There are two forms of reproduction: sexual and asexual. Sexual reproduction is the combination of the gametes from two parental organisms, while asexual reproduction produces offspring from one parent, that are genetically identical. While both processes are vastly different, they each have drawbacks and advantages.       Sexual reproduction requires much more energy because it involves several resource-intensive processes. These include finding and attracting a mate, producing gametes (sperm and eggs), and often investing in courtship behaviors or physical displays. Additionally, after mating, there may be further energy spent on nurturing and protecting offspring. In contrast, asexual reproduction only requires one organism to produce offspring, without the need for a mate or the complex processes associated with sexual reproduction, requiring much less energy. Asexual organisms also oftentimes have very large ...

Sexual Selection Natural selection is not the battle to survive, but the battle to reproduce viable offspring. This high need and battle to find a mate and produce offspring leads to sexual selection. If the main goal is to produce the most, or fittest offspring, animals need to be choosey with whom they are mating. Just as natural selection allows the most fit alleles to be passed along and the least fit to die, sexual selection makes certain traits more or less common due to their ability to find or attract a mate .  Everything is a delicate balance of trade-offs in evolution. For the process of mating and producing offspring, each sex has their own challenges. For the females, it takes a great deal of energy and resources to create and carry offspring. For the males, mating does not require nearly as much energy. Because of this dichotomy, females are typically the ones choosing who they will mate with. If they are going to use that much energy to produce this offspring, then th...

Species, Speciation... and Definitions The biological species concept defines species as members of populations that have the ability to interbreed. Their appearance does not affect whether they could be deemed as the same species, as some animals within a species look similar and some look different. One of the difficulties with this concept is that some organisms within the same species have qualities that allow them to physically mate with each other, but are held back by a barrier of some sort (maybe a mountain or a highway separates them). How big would this separation have to be to consider them two different species. The distances between species becomes a strong question in the case of ring species. Ring species are a series of populations that live in the form of a ring, in which they all interbreed with populations near them, except for populations on the far ends of the rings. This then poses the question, are each their own species, or are the ones that interbreed a species...

 Genetic Drift Genetic drift is a change in gene or allele frequencies due to random chance. In the bottleneck effect seen on the top illustration, there are 6 different colors that could represent 6 different species. Some sort of bottlenecking event occurs. An example of this would be a natural disaster like a forest fire. This might kill off some or all of certain species, leaving only a few behind. In this example, only 3 colors (or species) survived. Then, through a process of evolution and selection, the 3 remaining species will continue to reproduce and create a new community of species. In the second image, the founder effect shows when a species moves to a new geographical location and are able to survive, they can also create an entirely new community of species. For example, in the image the mainland has multiple different colors of bugs. One day a green and pink bug fly to island 2 and land there. No other animals are on that island, and the green and pink bugs will be ...

It Gets Complicated Plasticity is the ability of an organism's phenotype, or physical expression of a trait, to change in the presence or absence of certain environmental conditions. To determine an organism's plasticity (let's say a moth whose wings might change colors to match their environment), you would need to establish the trait you are going to study. Once you have established that the color of the wings is the trait you are going to study, gather many moths and put them in a similar colored environment. Document the color and pattern of their wings, and after a select period of time, move them to a new environment (or many new environments) to see if their color or pattern changes in response to the conditions. If a change is noticed, repeat the study for validity of results. Make sure to eliminate outside variables by feeding them at the same time, providing the same amount of light, and ensuring all organisms being compared are the same gender etc. If the organis...

 Genotypes and Phenotypes How does it make sense that selection acts on the phenotype when we know that the genotype is what is passed to the next generation: To answer this question, I think that it is important that we first illustrate the differences between a phenotype and a genotype. A genotype is an organism's genes. This is the molecular makeup of their being, their code for everything that makes them, well, them. Genotypes change throughout generations and are susceptible to mutations and recombination. Both of these factors cause genotypes to shift and change, creating changes in the organism and their offspring. Phenotypes are the physical representation of these genes. We see phenotypes through the traits that an organism has. Someone might have brunette or blonde hair, but they have it due to the combination and order of their specific genome. Examples of phenotypes include colors of petals, skin, and eyes, length of legs, blood type, stem thickness, etc.  When loo...