Biodiversity and Evolution Overview

Biodiversity and the Unity and Diversity of Life

• Biodiversity encompasses the variation of life at all levels, from genes to ecosystems.
• It's crucial due to its connection to human health.
• Biodiversity shows both the unity and diversity of life.
• Unity arises from shared ancestry; diversity reflects environmental influences.

Evolution: A Pattern and Process

• Evolution occurs in populations, not individuals, and isn't goal-directed.
• It represents a change in allele frequencies over generations.
• Heritable traits aid descendants in natural selection.
• Populations are the smallest units capable of evolving.

Supporting Evidence for Evolution

• Fossil record, homologies, direct observations, and molecular DNA all support evolution.
• Evolution is both a pattern and a process.
• Natural selection drives the patterns observed over time.
• Species were once believed to be immutable.
• Early understandings of species' immutability were influenced by religious beliefs on the Creator's plan.
• Natural theology, the idea that natural structures reflect a divine plan emerged from Linnaeus's work
• Georges Cuvier, a founder of paleontology, observed similar organisms across strata, suggesting catastrophic events, not gradual change.
• Catastrophism hypothesizes that existing species are created successively, not evolving
• James Hutton and Charles Lyell proposed the concept of uniformitarianism to understand that the same processes that operate now have operated throughout time
• The Earth is 4.6 billion years old, showing a long span of time for evolution to occur.
• Malthus's economic theories showed that populations grow exponentially but food supply does not, leading to competition among organisms
• Lamarck incorrectly proposed that acquired traits during an organism's lifetime can be passed to offspring. He also proposed that organisms have an inherent drive towards complexity.
• Individuals match their environment through inherited adaptations.
• Fitness measures an organism's contribution to the gene pool of the next generation.
• Adaptations are traits that enhance an organism's fitness in its environment.

Natural Selection

• Individuals in populations show variations in traits.
• Traits are inherited from parents to offspring.
• Species can produce more offspring than the environment can support.
• Limited resources lead to competition and differential survival.
• Individuals with traits that enhance survival in a specific environment tend to leave more offspring.
• Natural selection does not lead to a specific goal.
• Artificial selection is different from natural selection because it is controlled by human choice and not environmental pressures.
• Individuals do not evolve, natural selection acts on heritable traits.

Evidence and Mechanisms of Evolution (continued)

• Vestigial structures are remnants of structures that have lost their original function.
• Convergent evolution shows similar characteristics arising independently in different lineages (analogous structures).
• Homologous characteristics evolved from a common ancestor.
• Phylogenetic trees show evolutionary relationships with a root (common ancestor), branches, nodes (divergence points), and tips (taxa, species).
• Endemic species are found only in one geographic location.
• Microevolution involves genetic changes within a population.

Variation

• Mutations are random changes in DNA sequence and are the ultimate source of genetic variation (and evolution).
• Mutations aren't always beneficial.
• Recessive alleles may be masked in heterozygotes.
• Mutations must occur in the germline to be heritable.

Prokaryotes

• The domains are Eukarya (eukaryotes), Bacteria, and Archaea (prokaryotes).
• Prokaryotes are widespread and adaptable to diverse environments.
• Prokaryotes exhibit various shapes (spheres, rods, spirals).
• Prokaryotes reproduce asexually by binary fission.
• Many prokaryotes use different metabolic strategies like photoautotrophy, chemoautotrophy, photoheterotrophy, and chemoheterotrophy.
• Bacterial cell walls contain peptidoglycan.
• Prokaryotes play crucial roles in decomposition and nutrient cycling.
• Some prokaryotes cause disease through exotoxins or endotoxins.

Eukaryotes

• Eukaryotes have a nucleus and membrane-bound organelles.
• Mitochondria and plastids may have originated from prokaryotic endosymbionts.
• Endosymbiotic theory proposes that eukaryotic organelles arose from engulfed prokaryotes.

Protists

• Protists are a diverse group of mostly unicellular eukaryotic organisms.
• Protists are incredibly important to global ecosystems: they are primary producers.
• Protists may be photosynthetic, heterotrophic, or mixotrophic.
• Protists have several roles in the environment and as diseases.
• Examples: diatoms, brown algae, Giardia, Plasmodium (malaria), Phytophthora (Sudden Oak Death).

Plants

• Plants adapted to terrestrial life through various evolutionary innovations, like sporopollenin, embryos, vascular tissue, seeds, and flowers.
• Challenges of adapting to land included gravity, lack of water, and environmental fluctuations.
• Plants evolved adaptations like spores, multicellular embryos, sporangia, gametangia, and apical meristems.
• Stomata allow plants to exchange gases with the atmosphere.
• Plants produce secondary metabolites for defense.
• Vascular tissue transports water and nutrients, providing structural support.
• Important plant secondary compounds: Alkaloids, Terpenes, Tannins, and Flavonoids.
• Seeds allow for dormancy and dispersal.
• Gymnosperms and angiosperms are two major groups of seed plants.
• Angiosperms have flowers.

Plant Classification

• Plants have distinct evolutionary groups, categorized based on characteristics like reproductive structures.
• Sporophyte (diploid) and gametophyte (haploid) generations are emphasized.