biology essay topics

biology essay topics

Exploring the Intricacies of Evolutionary Biology: An In-Depth Analysis

1. Introduction to Evolutionary Biology

A basic understanding of genetics and some knowledge of population biology are the prerequisites required. Our focus is on the application of evolutionary biology to the actual workings of the living world. The history of life is often epitomized by the concept of the “tree of life,” a metaphor of life’s history that dates back to Darwin and his landmark book On the Origin of Species in 1859. The “tree of life” is a visual representation of the shared history of all life on Earth, and it is to be understood to be primarily an evolutionary tree where all life on Earth is related by descent from a common ancestor, both horizontally and vertically.

Evolution seeks to understand the processes that have transformed life on Earth from its earliest forms to the vast diversity that characterizes the planet today, from the molecular level to the broader spectrum. Evolutionary biology is concerned with how and why various traits are distributed through populations and among more or less closely related species. It is both a powerful unifying theme that can be used to better understand biology and an exacting discipline that continues to play a central role in shaping the way we think about life and the living world. This contribution serves to synthesize topics covered in the discipline. It is courses designed to describe, in as straightforward a manner as possible, some of the intricate and sometimes complex ways in which we may better understand the extensive field of evolutionary biology by reconstructing the evolutionary processes responsible for the divergence of species.

2. The Mechanisms of Evolution

Mutation is the ultimate source of variation that arises because of DNA copying errors, metagenomics, and physical or chemical agents. Mutation is fallible and usually depletes variation unless the rate of mutation (U) is greater than the rate of mutation loss (U). The overall impact of mutation on gene proportions in meiosis is to set an upper limit on the level of polymorphism that can be maintained. No mechanism is known that can maintain separate alleles at more than a few loci in a modular polymer character. Ultimately, gene evolution is the product of specific populations, and the role of genetic drift is clear. However, there are four evolutionary forces that have adjoined the first genetic population. Mutation is often the agent of static proportion, which allows a mutation in the gene to reach polymorphism. Genetic recombination can separate benefits from beneficial mutations. Finally, gene flow greatly increases the rate of selection. Population genetics is the study of allele patterns maintained in two separate populations. It is especially unimportant to the controlled study of alleles in two genetically identical populations that arise by splitting a within-population of a single large panmictic population.

1. Mutation is the source of novel variation in any gene pool and can provide new beneficial alleles. 2. Genetic variation that exists in a gene pool or specific population was created initially by mutation. 3. Genetic variation was subsequently augmented by recombination. 4. Genetic variation can be introduced into a population from another population large enough for the alleles to be passed.

There are four fundamental and inter-related ways to introduce novel heritable variation into a population:

3. Adaptation and Natural Selection

When a feature improves the reproductive success of an organism, it will, over time, become more common in a population. This outcome happens because natural selection promotes successful features of successful organisms. Teleologically: Nature selects, and selects for, features adapted to chance and necessity. Many students have difficulty answering the following two questions: “What is evolution?” and “What produces adaptations?” We explain them here. Evolution (biological) is the process of change in the genetic composition of populations. Adaptation is a heritable feature of an organism that promotes survival or reproduction and thus contributes to evolution, either because it enhances individual fitness or because it evolved through natural selection for its current function. Thus, biological evolution is the result of genetic change produced by natural selection. The way neo-Darwinists explain adaptive evolution is thoroughly teleological, but the primary mode of adaptive evolution, natural selection, is not teleological.

The primary evolutionary explanation for current biological design, and the reason it’s a basic principle of evolutionary theory, is that all the specialized structures, functions, and behaviors of organisms function to help them survive or reproduce. These features are called adaptations. The genesis of historical evolutionary adaptations, especially complex or rare ones, is an intriguing and difficult issue, and adaptation is the topic of much evolutionary research.

Adaptation and Natural Selection

1. What are the two primary components of adaptation? What are their fates? 2. Describe how natural selection is the driving force for adaptation. 3. How do evolutionary biologists normally observe natural selection? 4. Why does a population become more adapted to its local environment over time? 5. Can other components of the evolutionary process lead to adaptive evolution? Why or why not?

Review Questions

4. Speciation and Diversification

Speciation is the process of producing new forms of living things in nature, apparently the day-by-day processes. It is problematic because we can see new species now and then, but we do not have adequate evidence about how most past species were formed, and we have very little evidence that new species are being formed before our very eyes. Exactly what separates one species from another is also thoroughly problematic in practice, with our hasty, offhand decisions often made while peering through a pudgily distorting taxonomic key. Therefore (and quite differently from grad students in redwoods with sharp machetes), we largely avoid talking about speciation or about the many general ‘species problems’ that guide and distort that lurking concern, both of which we discuss with a better mix of sobriety and salubriousness when the ground allows for that more elevated perspective. We confine our attention here to the dynamics of reproductive isolation and how it is related to divergence and most probably underlies the process of speciation, dramatic though that term may be in human affairs.

5. Applications and Implications of Evolutionary Biology

Although we do not specifically address the many specific applications of evolutionary biology in this book, it is important to remind the reader that there are many reasons to be interested in evolutionary biology. Evolutionary biologists study life at every level, from individual genetic variation within populations to life history diversity within species, to species diversity at the family, order, and higher taxonomic levels. Translated into practical benefits for human society, fundamental research in evolutionary biology underlies our understanding of genetic diversity of populations. It underpins animal and plant breeding, and it is the basis of much medical and pharmacological work from parasite and insect resistance in crops and livestock to new drug discovery. Understanding the diversity of life and the origins of that diversity can inform ecosystem management, food security, and conservation policy. Evolutionary biologists are interested in the past, in how humans have arrived at the current situation, but the information generated from evolutionary studies can lead to a deeper and more profound appreciation of the world today and the worlds of the future.