APES - Evolution of Biodiversity

Evolution of Biodiversity

What is Evolution?

  • Evolution is the process through which populations of organisms change over generations.

  • Critical in Environmental Science as it provides insight into the relationships, traits, and adaptability of species.

  • Current Estimate: Approximately 8.7 million species on Earth.

  • Challenge: Difficulty in estimating due to vast unexplored areas such as oceans (5% explored).

  • Current Naming: Scientists have named about 2 million species.

Measuring Biodiversity

Concepts of Biodiversity

  • Species Richness: The total number of different species in a given area.

  • Species Evenness: The relative abundance of species in that area.

  • Importance: Baseline for determining ecosystem changes.

Species Diversity Measurement

  • Species richness and evenness are different types of measures.

  • A more even distribution of species indicates higher diversity.

Shannon-Wiener Index

  • Formula: H = -sum (Pi ln(Pi))

    • Pi: Relative abundance of each species (ni/N)

    • ni: Number of individuals of species "i"

    • N: Total number of individuals of all species.

  • Evenness (E): E = H/(lnR)

  • Range of H: From 0 (no biodiversity) to over 7 (high biodiversity).

Phylogenetic Relationships

  • Phylogeny: The evolutionary history and relationships among species.

  • Similarity of Traits: Indicates how closely related species are.

Misconceptions About Evolution

  • Humans did not evolve from monkeys; rather, both share a common ancestor.

  • Understanding evolutionary trees helps clarify these relationships.

Determining Phylogenetic Relationships

Methodology

  • Scientists analyze:

    • Morphology: Physical structure similarities.

    • Behavior: Patterns of behavior among species.

    • Genetics: Genetic similarities and differences.

Fill-in-the-Blank Overview

  • Descendants Examples: Lancelet, Lamprey, Trout, Lizard, Chipmunk.

  • Common Ancestor: Indicates historical speciation events.

Understanding Phylogenetic Trees

  • Used to illustrate how species are related and track morphological changes over time.

Evolutionary Processes

Key Learning Outcomes

  • Identify processes that cause genetic diversity.

  • Understand artificial and natural selection.

  • Describe random evolution processes.

The 5 Fingers of Evolution

  1. Mutations

  2. Non-random mating

  3. Gene flow

  4. Small populations

  5. Adaptations

Natural Selection

  • Defined as the survival and reproduction influenced by the environment.

  • Organisms best adapted to their environments pass traits to offspring.

Genetic Diversity Creation

  • Evolution: Change in genetic composition over time.

  • Microevolution: Changes below species level.

  • Macroevolution: Evolution resulting in new higher taxonomic levels.

Example of Evolutionary Change

  • Overview of genetic changes in human populations and historical diversification events.

Genotypes and Phenotypes

  • Genotype: Complete set of genes.

  • Phenotype: Expressed traits influenced by genotype.

Mutation as Evolution Driver

  • Mutations can introduce beneficial traits enhancing survival.

Recombination in Evolution

  • Combines genetic information to create variance, aiding adaptability (e.g., in immune responses).

Artificial Selection

  • Humans select breeding individuals for desired traits.

  • Forms diverse breeds and crops (e.g., domesticated dogs).

Natural vs. Random Processes in Evolution

  • Natural selection emphasizes survival based on advantageous traits.

  • Random processes include mutations, gene flow, and genetic drift.

Gene Flow Examples

  • Gene flow can alter allele frequencies and enhance genetic variation, as shown in the Florida panther case.

Genetic Drift Explained

  • Genetic drift affects small populations significantly by randomly changing allele frequencies.

Bottleneck Effect

  • Caused by drastic reductions in population, prompting decreased genetic diversity and increased extinction risk.

Founder Effect

  • New populations carry limited genetic diversity from a small group of colonizers, as seen in island populations.

Key Ideas of Evolution

  • Excess offspring, survival challenges, trait differences, heritability of traits, and reproduction capability.

Speciation Processes

Allopatric & Sympatric Speciation

  • Allopatric Speciation: Geographic isolation leading to reproductive isolation.

  • Sympatric Speciation: Evolution without geographic boundaries, often through polyploidy in plants.

Factors Influencing Evolution Pace

  • Evolution rates vary based on environmental adaptability, generation times, and genetic variations.

Niches and Species Distribution

Key Concepts

  • Fundamental Niche: Ideal abiotic conditions for survival.

  • Realized Niche: Actual conditions where species thrive.

Species Niches Explanation

  • Niche generalists adapt easily to changing environments; specialists struggle.

Impact of Environmental Changes

  • Altered distributions can lead to extinction when species can't adapt to new conditions.

  • Mass Extinctions: Historic events where many species died out rapidly.

6th Mass Extinction

  • Current biodiversity crisis largely driven by human activities affecting habitats and climates.