Adaptations: Natural and Artificial Selection

• Adaptations are traits that help species survive and reproduce.

Behavioral Adaptations

• Involve changes in behavior.
• Examples include hibernation, migration, and communication.

Structural Adaptations

• Physical features of an organism.
• Examples include gills for breathing, long necks for reaching food, and fur color for camouflage.

Functional Adaptations

• Internal processes or functions of an organism.
• Examples include camel humps for water and fat storage and snake venom for predation.

Artificial Selection

• Humans select desired traits in organisms.
• They then breed those organisms together to ensure offspring inherit those traits.

Natural Selection

• Environmental pressures cause organisms lacking optimal traits to die.
• Organisms with suitable traits survive and reproduce more effectively.
• Offspring inherit the optimal traits, increasing their survival in the environment.

Natural Selection and Fitness

• Fitness, or survival of the fittest, is crucial in natural selection.
• Individuals with the best traits are more likely to survive and reproduce.
• Their offspring then inherit those beneficial traits.
• An individual's fitness dictates their likelihood of survival and reproduction in natural selection.

Natural Selection and Descent with Modification

• Continuous natural selection leads to significant changes in organisms over time.
• Accumulation of desired traits for the environment results in substantial differences across generations.
• Over extended periods, this can eventually lead to the evolution of new species, as described by Darwin’s Theory of Evolution.

Comparative Embryology

• Embryos of various organisms exhibit similarities, suggesting a shared common ancestor.

Fossil Records

• Fossils demonstrate similar bone structures and descent with modification over time.
• Dating methods help identify extinct species and establish evolutionary connections between them.

Homologous Structures

• Organisms possess similar bone structures, indicative of common ancestry.
• Example: the "one-two-many" bone structure pattern observed in many vertebrate limbs.

Vestigial Structures

• Some organisms have structures that were useful in past generations but are reduced in size and not currently used.
• Example: wisdom teeth in humans.

Molecular/Genetic Homology

• Organisms share similar genetic sequences, highlighting their evolutionary relationships.

Analogous Structures

• Organisms have structures with similar functions but different evolutionary origins.
• These structures evolved independently in response to similar environmental pressures.

Homologous Structures

• Similar bone arrangements and structures among different species.

Analogous Structures

• Structures in different species with similar functions but distinct origins.

Vestigial Structures

• Structures that were useful in past generations but no longer serve their original purpose in current generations.

Disruptive Selection

• Favors extreme traits over intermediate traits within a population.

Stabilizing Selection

• Favors intermediate traits over extreme traits, leading to a reduction in variation.

Directional Selection

• Favors one extreme phenotype, causing a shift in the population’s trait distribution.

Genetic Drift

• Random changes in allele frequencies within a population.
• Bottleneck Effect: A random event drastically reduces population size, leading to survival of random organisms irrespective of traits.
• Examples of such events include a human stepping on a population or natural disasters like droughts and hunting.
• Founder's Effect: A small, random group of individuals migrates to a new location and establishes a new population.

Competition

• Organisms compete for limited resources such as food, shelter, and mates.
• Organisms with advantageous traits are more likely to survive, reproduce, and pass on their genes, leading to changes in the gene pool.

Behavioral Isolation

• Two populations have different mating rituals that prevent interbreeding.

Ecological Isolation

• Two populations rarely interact because they prefer different environments and resources.

Temporal Isolation

• Two or more populations have different reproductive seasons, preventing interbreeding.

Geological Isolation

• Two populations are physically separated by geographical barriers such as rivers or mountains.

Reproductive Isolation

• Two populations are unable to interbreed and produce fertile offspring.
• Mechanical Isolation: Physical incompatibility of reproductive organs prevents mating.
• Gametic Isolation: Sperm from one population cannot fertilize the egg of another.
• Habitat Isolation: Different species occupy different habitats within the same area, reducing the chance of interaction.

Prezygotic Isolation

• Isolation occurs before fertilization.

Postzygotic Isolation

• Isolation occurs after fertilization.
• These isolation methods lead to speciation by preventing gene flow between populations.
• Isolated populations evolve independently through natural selection and genetic drift.
• Over time, the accumulation of genetic differences can lead to the formation of distinct species.

Bacterial Evolution

• Bacteria can develop resistance to antibiotics through mutations.
• Bacteria with mutations that confer antibiotic resistance are more likely to survive and reproduce in environments where antibiotics are present, increasing the prevalence of resistance.

Domains

• Eukarya: Organisms with cells containing nuclei.
• Bacteria: Prokaryotic organisms with cell walls made of peptidoglycan.
• Archaea: Prokaryotic organisms that thrive in extreme environments and do not cause diseases.

Eukarya Domain

• Includes organisms with nuclei.
• Can be unicellular or multicellular.
• Exhibit both autotrophic and heterotrophic modes of nutrition.
• Their cells are eukaryotic.

Bacteria Domain

• Consists of unicellular organisms.
• Can be autotrophic or heterotrophic.
• Their cells are prokaryotic.

Archaea Domain

• Comprises unicellular organisms.
• Can be autotrophic or heterotrophic.
• Their cells are prokaryotic.

Kingdoms

• Protista, Fungi, Plantae, Animalia, Eubacteria, Archaebacteria.

Protista Kingdom

• Belongs to the Eukarya domain.
• Includes all eukaryotes that cannot be classified as plants, fungi, or animals.
• Can be unicellular or multicellular.
• Exhibit both autotrophic and heterotrophic modes of nutrition.

Fungi Kingdom

• Belongs to the Eukarya domain.
• Feeds on dead or decaying matter.
• Can be unicellular or multicellular.
• Heterotrophic.
• Eukaryotic.

Plantae Kingdom

• Belongs to the Eukarya domain.
• Includes autotrophic photosynthetic organisms.
• Multicellular.
• Eukaryotic.

Animalia Kingdom

• Belongs to the Eukarya domain.
• Comprises heterotrophic organisms without cell walls.
• Multicellular.
• Eukaryotic.