Introduction to Biology Pt. 1: Species and Reproduction

Introduction to Biology Pt. 1: Species and Reproduction

When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine.

In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning.

Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.

An important component of biology is reproduction, or the process by which an organism creates a similar offspring to itself. It is an important part of biology because, as we all know, biology is the study of life and we would not have come to existence if it weren’t for reproduction. As is the case in the circle of life, the young have to replace the old. 

Reproduction behaves as an instrument in the production of new species. Speciation is the evolutionary process in which a population splits into distinct groups called a species.

Because scientists have a hard time identifying a species in nature, they must observe animal  reproduction in order to figure out  what the groups are made up of. There are two ideas often used to classify a species- the biological and the phylogenetic species concepts.  

According to the biological species concept, a species is defined as members within a population that interbreed with each other and produce viable offspring.

However, this definition is highly debated and does not satisfy the discoveries of all naturalists. This is because it does not consider certain organisms including those that reproduce asexually and hybrids of different taxa along with other limitations. 

There are two forms of reproduction- asexual and sexual. Asexual reproduction requires a single organism in order to produce a new individual, therefore all of the offspring from this type of reproduction will be completely identical to its parent.

This type of reproduction often occurs in single-celled organisms and allows for dramatic growth in population. A drawback to asexual reproduction, though, is because all of the offspring are clones, there is a lack of genetic diversity and its population becomes vulnerable to disease or other changes in the environment.

Sexual reproduction is the combination of two gametes, to produce a unique offspring. In the case of primates, a group that includes apes and us humans among other species, the gametes produced are the ovum (egg) from a female and sperm from a male.

Each gamete contains half the genetic material required of normal cells. During sexual intercourse, reproduction takes place when the sperm fertilizes the egg and forms a zygote. The DNA of a zygote is a combination of genomic material from both the mother and father and contains the information required to produce a new individual.

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This process is more time consuming and produces fewer offspring compared to asexual reproduction, but it allows for more genetic diversity. Species that reproduce sexually become more advantageous in the event that their environment becomes unstable or a new disease is introduced. Random mutations may occur and certain individuals will be favored by natural selection, or survival of the fittest. 

There are also organisms that undergo both asexual and sexual reproduction! Whenever their environment is favorable, they implement asexual reproduction in order to take advantage of the conditions. This allows for exponential growth in their population.

Once unfavorable environmental factors take place they switch to sexual reproduction, creating greater variation in the gene pool. The individuals with advantageous traits become better suited for survival in the new conditions and will produce offspring with these traits, thus continuing their species. 

Hybrids are the offspring resulting from the interbreeding of two organisms from different species. Many hybrids are sterile; this means that although they can survive to adulthood, they will be unable to produce offspring that can pass their genes onto the next generation.

This is due to the concept of reproductive isolation, in which there are barriers to prevent speciation.

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Some obstacles include genetic and morphological differences and physiological rejection of fertilization. In some cases, sterility is due to the different number of chromosomes, molecules containing genetic material, between the two species.

This difference is present in the cross between a donkey and a horse. Donkeys have 62 chromosomes and horses have 64, resulting in a sterile mule or hinny with 63 chromosomes.

These structural chromosomal differences hinder the formation of viable gametes because normal  pairing and segregation in meiosis are interrupted.

These examples highlight the limitations of the biological species concept and suggest a need to better classify species. With the increased knowledge of genetics, the phylogenetic species concept has become more commonly accepted than the biological species concept. 

The phylogenetic species concept defines a species by its evolutionary development and diversification from another group.

Technological advancements have allowed for a vast collection of DNA sequences from numerous species. Analyzing these DNA sequences have allowed individuals to be traced to a common ancestor through their genealogical relationships to other species. This monophyletic group is then classified as a species. 

The phylogenetic species concept is broader and solves the problems introduced by the biological species concept. Another strength of this notion is that populations do not have to be observed for interbreeding, as this can be difficult to keep up with in certain species.

Morphology is observed and members of a monophyletic group have to share numerous characteristics that are absent in other species. Scientists can observe this by studying fossil records, making this a better approach in paleontology since reproduction cannot be observed in extinct animals like dinosaurs and neanderthals.

While the phylogenetic species concept solves the underlying issues of the biological species concept, it is also flawed. Because all individuals have a common ancestor at some point in their evolutionary history, scientists have to decide how recent the common ancestor has to be when forming a monophyletic group.

This creates subjectivity, when a goal in research is objectivity and consistency. Another issue is that this concept promotes the division of species into even smaller groups from the slightest variation.

Morphological differences within a group are common and are often still connected by gene flow. In the case of the human species, there is substantial physical variation present across continents, yet every one of us are  of the same species.  

There are a number of other species concepts that are discussed in the field of research, but at the end of the day no two researchers will be able to agree on a universally applicable concept that favors the conditions of their study. Until such a thing can be done, it is the taxonomist’s decision to commit to a species concept and provide limitations to define their classification in a way that best aligns to their research. 

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