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What Is Evolution In Biology

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What Have Genes Got To Do With It

Fossils & Evidence For Evolution | Evolution | Biology | FuseSchool
  • The mechanisms of evolution operate at the genomic level. Changes in DNA sequences affect the composition and expression of our genes, the basic units of inheritance.
  • To understand how different species have evolved we have to look at the DNA sequences in their genomes.
  • Our evolutionary history is written into our genome. The human genome looks the way it does because of all the genetic changes that affected our ancestors.
  • When DNA and genes in different species look very similar, this is usually taken as evidence of them sharing ancestors.
  • For example, humans and the fruit fly, Drosophila melanogaster, share much of their DNA. 75 per cent of genes that cause diseases in humans are also found in the fruit fly.
  • DNA accumulates changes over time. Some of these changes can be beneficial, and provide a selective advantage for an organism.
  • Other changes may be harmful if they affect an important, everyday function. As a result some genes do not change much. They are said to be conserved.

Evolutionary History Of Life

The Earth is about 4.54 billion years old. The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. Microbial mat fossils have been found in 3.48 billion-year-old sandstone in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland as well as “remains of biotic life” found in 4.1 billion-year-old rocks in Western Australia. Commenting on the Australian findings, Stephen Blair Hedges wrote, “If life arose relatively quickly on Earth, then it could be common in the universe.” In July 2016, scientists reported identifying a set of 355 genes from the last universal common ancestor of all organisms living on Earth.

More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth’s current species range from 10 million to 14 million, of which about 1.9 million are estimated to have been named and 1.6 million documented in a central database to date, leaving at least 80 percent not yet described.

Typological Essentialist And Transformationist Thinking

Misunderstandings about how variation arises are problematic, but a common failure to recognize that it plays a role at all represents an even a deeper concern. Since Darwin , evolutionary theory has been based strongly on population thinking that emphasizes differences among individuals. By contrast, many naïve interpretations of evolution remain rooted in the typological or essentialist thinking that has existed since the ancient Greeks . In this case, species are conceived of as exhibiting a single type or a common essence, with variation among individuals representing anomalous and largely unimportant deviations from the type or essence. As Shtulman notes, human beings tend to essentialize biological kinds and essentialism is incompatible with natural selection. As with many other conceptual biases, the tendency to essentialize seems to arise early in childhood and remains the default for most individuals .

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What Is The Main Goal Of Evolution

Evolution describes changes to the inherited traits of organisms across generations. Evolutionary change is not directed towards a goal, nor is it solely dependent on natural selection to shape its path. Ecology, as with any biological discipline, is rooted in evolutionary concepts and best understood in its terms.

Biotechnology Genetic Engineering And Genomics

Evolutionary Biology

Biotechnology in the general sense has been an important part of biology since the late 19th century. With the industrialization of brewing and agriculture, chemists and biologists became aware of the great potential of human-controlled biological processes. In particular, fermentation proved a great boon to chemical industries. By the early 1970s, a wide range of biotechnologies were being developed, from drugs like penicillin and steroids to foods like Chlorella and single-cell protein to gasoholâas well as a wide range of hybrid high-yield crops and agricultural technologies, the basis for the Green Revolution.

Escherichia coli

Recombinant DNA

Biotechnology in the modern sense of genetic engineering began in the 1970s, with the invention of recombinant DNA techniques.Restriction enzymes were discovered and characterized in the late 1960s, following on the heels of the isolation, then duplication, then synthesis of viral genes. Beginning with the lab of Paul Berg in 1972 , molecular biologists put these pieces together to produce the first transgenic organisms. Soon after, others began using plasmidvectors and adding genes for antibiotic resistance, greatly increasing the reach of the recombinant techniques.

Molecular systematics and genomics

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The Increase Of Genetic Complexity Follows Moore’s Law

Biological evolution is traditionally studied in two aspects. First, paleontological records show astonishing changes in the composition of major taxonomic groups of animals and plants deposited in sedimentary rocks of various ages . Aquatic life forms give rise to the first terrestrial plants and animals, amphibians lead to reptiles including dinosaurs, ferns lead to gymnosperms, and then to flowering plants. Extinction of most dinosaurs is followed by the spread of mammals and flying descendants of dinosaurs called birds. Second, Darwin’s theory augmented with statistical genetics demonstrated that heritable changes may accumulate in populations and result in replacement of gene variants . This process drives microevolution, which helps species to improve their functions and adjust to changing environments. But despite the importance of these two aspects of evolution, they do not capture the core of the macroevolutionary process, which is the increase of functional complexity of organisms.

Functionality of genome regions can be inferred from their conservation in evolution. Conserved sequences include the majority of genes and regulatory modules such as promoters and enhancers . Regulatory regions are less stable than genes, and thus, they are not always highly conserved in evolution. An additional criterion of functionality is the absence of transposable repeats . Based on our estimate, ca. 15% of mammalian genome is transposon-free, and therefore, likely functional .

Visible Evidence Of Ongoing Evolution: Darwins Finches

From 1831 to 1836, Darwin traveled around the world, observing animals on different continents and islands. On the Galapagos Islands, Darwin observed several species of finches with unique beak shapes. He observed these finches closely resembled another finch species on the mainland of South America and that the group of species in the Galápagos formed a graded series of beak sizes and shapes, with very small differences between the most similar. Darwin imagined that the island species might be all species modified from one original mainland species. In 1860, he wrote, seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.

Darwins Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources. This illustration shows the beak shapes for four species of ground finch: 1. Geospiza magnirostris , 2. G. fortis , 3. G. parvula , and 4. Certhidea olivacea .

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Properly understood, evolution is a scientific theory about the development of life and is consistent with Christian theology.

What Is The Evidence For Evolution

What is the Evidence for Evolution?

The Theory of Evolution is one of the best-substantiated theories in the history of science. It is supported by evidence from a wide variety of scientific disciplines, including genetics, which shows that different species have similarities in their DNA.

There is also evidence supporting the Theory of Evolution in paleontology and geology. This is through the fossil record, which shows how that species that existed in the past are different from those present today, according to Bruce S. Lieberman and Roger L. Kaesler in “Prehistoric Life: Evolution and the Fossil Record” .

There is also evidence for Darwin’s theory found in developmental biology. It has been discovered that species that seem very different as adults pass through similar stages of embryological development, suggesting a shared evolutionary past, according to the open-access textbook “Concepts of Biology.”

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Evolution Of Evolvability: Dedicated Mechanisms For Evolution

All organisms possess a certain degree of evolvability, i.e., the ability to evolve. At the most basic level, evolvability stems from the theoretical impossibility of error-free replication. Genomic variation in evolving organisms is created by a combination of intrinsic replication errors, recombination and mutations induced external agents . An intriguing, fundamental question in evolutionary biology is whether or not evolvability itself can evolve under selection, or put another way, whether there are dedicated mechanisms of evolution . The prevailing wisdom among biologists seems to be that evolvability is not selectable but is simply maintained at a sufficient level by inevitable errors at all levels of biological information processing. Under this view, selection is always directed at minimization of the error rate but the ability to attain perfection is limited by genetic drift resulting in sufficient evolvability . Evolutionary biologists are usually suspicious of the evolution of evolvability, generally under the old adage, evolution has no forecast.

In parallel with experimental studies, several theoretical models have been developed that characterize evolvability as a selectable trait in fluctuating environments . Thus, on the whole, and general theoretical doubts notwithstanding, evolution of evolvability appears to be an intrinsic and fundamental, if still poorly understood, aspect of the evolutionary process.

What Is Evolution A Level Biology


. Subsequently, one may also ask, what are the 4 principles of evolution?

There are four principles at work in evolutionvariation, inheritance, selection and time. These are considered the components of the evolutionary mechanism of natural selection.

Additionally, what are the 3 types of evolution? Types of Evolution. Evolution over time can follow several different patterns. Factors such as environment and predation pressures can have different effects on the ways in which species exposed to them evolve. shows the three main types of evolution: divergent, convergent, and parallel evolution.

People also ask, what is a species a level biology?

The Biological Species Concept- a species contains all organisms that are capable of breeding together to produce living, fertile offspring. Classification hierarchy comprises the taxa: domain, kingdom, phylum, class, order, family, genus and species.

What is a gene pool A level biology?

Gene pool refers to the total number of genes of every individual in a population. It usually involves a particular species within a population. A large gene pool indicates high genetic diversity, increased chances of biological fitness, and survival.

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Evolution As An Emergent Property Of Life

A key part of any definition of life is that living organisms reproduce. Lets now add a couple of observations:

  • The process of reproduction, while mostly accurate, is imperfect. When cells divide, they have to replicate their DNA. Although DNA replication is highly accurate, it still makes about 1 mistake in 10 million nucleotides. Over generations, the population will contain lots of heritable variation.
  • The population of a given type of organism will tend to grow exponentially, but will reach a limit, where the individuals have to compete with each other for the limiting resource

Evolutionary Biology Concentration Area Electives


A maximum of 2 independent studies or tutorials may count toward the major. A maximum of 2 alternate electives may count toward the major

  • 1 independent study, tutorial or seminar on an evolution-related topic, taken with a concentration area faculty member or with approval of the concentration area advisor.
  • BIOLOGY 293 / 493 Research Independent Study OR
  • BIOLOGY 490T Tutorial OR
  • BIOLOGY 490S/590S Special Topics Seminar with area faculty or as approved by the area advisor
  • 1 course from the following list or other course as approved by the area advisor:
  • BIOLOGY 251L Molecular Evolution
  • BIOLOGY 255 Philosophy of Biology
  • BIOLOGY 267D Behavioral Ecology and the Evolution of Animal Behavior
  • BIOLOGY 268D Mechanisms of Animal Behavior
  • BIOLOGY 330L Comparative and Functional Anatomy of the Vertebrates
  • BIOLOGY 347L People and Plants
  • BIOLOGY 350 Complex Traits and Evolutionary Genetics
  • 1 course from the following list or other course as approved by the area advisor:
  • BIOLOGY 450S Genomics of Adaptation: A Modern Look at Evolution
  • BIOLOGY 453S Genes in an Ecological Context
  • BIOLOGY 460 Population Genetics
  • BIOLOGY 555S Problems in the Philosophy of Biology
  • BIOLOGY 556 Systematic Biology
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    Twentieth Century Biological Sciences

    At the beginning of the 20th century, biological research was largely a professional endeavour. Most work was still done in the natural history mode, which emphasized morphological and phylogenetic analysis over experiment-based causal explanations. However, anti-vitalist experimental physiologists and embryologists, especially in Europe, were increasingly influential. The tremendous success of experimental approaches to development, heredity, and metabolism in the 1900s and 1910s demonstrated the power of experimentation in biology. In the following decades, experimental work replaced natural history as the dominant mode of research.

    What Are The 3 Types Of Evolution

    Types of Evolution. Evolution over time can follow several different patterns. Factors such as environment and predation pressures can have different effects on the ways in which species exposed to them evolve. shows the three main types of evolution: divergent, convergent, and parallel evolution.

    What is the synonym of evolution?

    Synonyms of evolution The doctors say they are pleased with her progress. working out. expansion. the rapid expansion of private health insurance. extension.

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    The Dynamic Gene Universe

    For decades microbiologists knew that bacteria sometimes exchange genes . Moreover, the phenomena of transformation, acquisition of new traits via import of DNA from the environment and integration of the imported molecules into the bacterial genome, and transduction, transfer of genetic markers by bacteriophages, have been studied in considerable detail. In fact, transformation was the basis of the seminal 1944 experiments of Avery and colleagues which demonstrated that the genetic material of bacteria consisted of DNA . In addition, microbiologists realized that such HGT could exert well-defined, major biological effects such as conferring pathogenicity or antibiotic resistance on the recipients of horizontally transferred genes. However, all this knowledge notwithstanding, in the pregenomic era, HGT was considered a highly specialized genetic pathway rather than the mainstream of microbial evolution.

    Figure 3. Tree-like and web-like contributions in the evolution of nearly universal genes and the entire phylogenetic forest. The two heat maps schematically depict comparison of bacterial and archaeal genomes as described previously .

    Figure 4. The universal distribution of gene commonality in the microbial genomic universe: a generalized schematic. The three broken lines represent three exponential functions that fit the core , the shell and the cloud of prokaryotic genes .

    Evolution As A Scientific Theory

    Evolution & natural selection | Heredity & Evolution | Biology | Khan Academy

    In non-scientific contexts, theory usually means something like a guess . But in its scientific sense, a theory is a tested and well-confirmed explanation for a set of observations. The observations explained by the theory of evolution come primarily from the fossil record, comparative morphology, biogeography, and now most importantly, genetics. Evolution does not attempt to give a scientific explanation for the origin of life, but only for the development and diversification of lifeforms after the first life began.

    The theory of evolution states that all the lifeforms on earth share a common ancestor as a result of variation and selection over a very long time . Variation means that offspring are not exact replicas of their parents, and selection occurs when only some of those offspring go on to produce more of their own offspring. Common ancestry does not mean the species we find today have evolved from each otherdogs did not evolve from cats, and humans did not evolve from chimpanzees. Instead, if you go back far enough in the ancestral tree of any two organisms, common ancestry predicts that youll come to a grandparent of which both current organisms are descendants. For humans and our closest relatives the chimpanzees, you have to go back around 300,000 generations to find that common ancestor . What did that process look like?

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    The Study Of Structure

    Living things are defined in terms of the activities or functions that are missing in nonliving things. The life processes of every organism are carried out by specific materials assembled in definite structures. Thus, a living thing can be defined as a system, or structure, that reproduces, changes with its environment over a period of time, and maintains its individuality by constant and continuous metabolism.

    Evolution Adaptation And Model Organisms

    Biological evolution is the change in inherited traits over successive generations in populations of organisms. Adaptation is a key evolutionary process in which variation in the fitness of traits and species are adjusted by natural selection to become better suited for survival in specific ecological habitats. The environment acts to promote evolution through changes in development. Therefore, determining how developmental changes are mediated is critical for understanding the mechanisms of evolution.

    Biological processes are often studied in model organisms. A model organism is a species that is studied extensively in the laboratory with anticipation that the results can be applied to biological phenomena in general. Cave animals can serve as excellent models to study the relationships between the environment, evolution, adaptation, and development. Troglomorphic traits, including elongated appendages, lowered metabolism, specialized sensory systems, and loss of eyes and pigmentation have evolved as a response to the effects of perpetual darkness. In this article, we describe the characid fish Astyanax mexicanus, as a vertebrate model system for studying the developmental basis of evolution and adaptation to the cave environment.

    William R. Jeffery, in, 2012

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