Teorías Evolutivas y Biodiversidad

Evolutionary Theories

• Scientists believe life on Earth didn't always exist. 2.3 billion years ago, life emerged from chemical compounds, particularly those with carbon.
• An estimated 7.4 to 10 million different species inhabit Earth.
• Only 2 million species have been cataloged, representing roughly 90% of life forms still unknown.
• All current species likely evolved from common ancestors, some of whose remains are known through fossil records.

Origin of Life

• Life first developed in the oceans.
• Early life forms progressed from single-celled organisms to multicellular life, including plants.
• Plants produced oxygen, enabling subsequent animal evolution.
• Life subsequently colonized land and air environments.
• Biological research shows organisms continuously adapt and change over time.

Biodiversity

• Biodiversity encompasses the variety of living things, including animals, plants, bacteria and viruses. In addition, it includes ecosystems, genes of each species, and the ecological and evolutionary processes that occur at gene, species and ecosystem levels.
• Tropical regions have the highest biodiversity.
• At least half of Earth's plant species are found in Latin America, with a significant concentration in Ecuador, Colombia, and Peru. This high biodiversity is due to stable climates, plentiful water, and abundant resources.
• Latin America contains many endemic species, meaning they are only found in those regions.

Evolutionary Biology

• Evolutionary biology traces the history of life's development and diversity.
• The process of evolution encompasses the gradual transformation of existing species into new ones.
• This is a population change, not individual change. This process can take millions of years.
• Evolutionary processes can produce new species and explain variations between similar species with shared ancestors .

Pre-Evolutionary Concepts

• Creationism/Fixism: Ancient traditions held that all species were created separately and have remained unchanged.
• Anaximander: Believed in the transformation of life forms.
• Aristotle: Proposed a hierarchical system of life, with humans at the top (Scala Naturae).
• Heraclitus of Ephesus: Argued that all things change constantly.
• Plato: Emphasized that observed life forms are imperfect representations of ideal forms.
• Thomas Aquinas: Believed in both divine creation and the possibility of spontaneous generation.
• Georges-Louis Leclerc, Comte de Buffon: Noted that species change over time in response to environmental changes.
• Erasmus Darwin: Proposed that species change over time through natural means.
• James Hutton: Proposed gradual change and continuous processes in Earth's history (Uniformism).
• Nicolas Steno: Studied the nature and formation of fossils.
• Georges Cuvier: Studied fossils, supported the concept of extinction, and developed the theory of catastrophism in which new species were created after sudden natural disasters.
• Louis Agassiz: Believed in separate creations of species after catastrophic events.
• Charles Lyell: Developed uniformitarianism, and his theory on the evolution of the Earth influenced Darwin
• Alfred R. Wallace: Developed the theory of natural selection simultaneously with Darwin, which led to the development of a combined evolutionary theory by Darwin.

Darwin's Theory of Evolution by Natural Selection

• Darwin's theory proposes that species diverge gradually.
• Species arise from preexisting species.
• Natural selection drives the process by selecting individuals with beneficial traits, thus favouring their reproduction and the passing on those traits to successive generations.
• Darwin studied animals and plants, especially in Galapagos Islands, and observed various variations.

Neo-Darwinism (Modern Synthesis)

• This theory combines Darwin's natural selection with principles of genetics.
• It emphasizes the importance of genetic variation, mutations, and natural selection in driving evolution.

Punctuated Equilibrium

• Suggests evolution occurs in bursts of rapid change followed by periods of little or no change, rather than a gradual process as Darwin described.

Adaptations

• Physiological: Changes in internal functions. Example: Desert animals conserving water or plants modifying photosynthesis.
• Structural: Changes in body structure. Example: Camouflage or mimicry.
• Behavioral: Changes in how an organism interacts with its environment. Example: Migratory patterns or social structures.

Other Evolutionary Concepts

• Divergent Evolution: Different species evolve from a shared ancestor in different environmental conditions. Example: Whale and bear evolution.
• Convergent Evolution: Unrelated species develop similar adaptations in similar environmental conditions. Example: Bird and insect wings.
• Coevolution: Two or more species evolve in response to each other. Example: Flowers and pollinators.

Migration and Biodiversity

• Species migrate to find better conditions and resources.
• Species migrate to maintain their populations in different stages of the year.
• The environment plays a vital role when selecting for certain characteristics or traits.