Evolution and Speciation Quiz

Evolution, Speciation, and Biodiversity

• Evolution is the change in heritable characteristics of a population over generations.
• Lamarckism proposes inheritance of acquired traits, differing from Darwin's theory of natural selection.
• Natural selection is the mechanism of evolution where advantageous traits are passed on.
• Molecular evidence like DNA and protein sequences shows evolutionary relationships; the more similar the sequences, the closer the species.
• Sequence divergence correlates with evolutionary distance.
• Artificial selection is human-directed breeding for desirable traits.
• Homologous structures (e.g., pentadactyl limbs) share common ancestry despite different functions due to divergent evolution.
• Analogous structures arise from convergent evolution, where unrelated species evolve similar adaptations in similar environments.
• Speciation occurs with reproductive isolation (geographic, temporal, or behavioral).
• Allopatric speciation involves geographic separation; sympatric speciation occurs within overlapping ranges.
• Biodiversity encompasses species, genetic, and ecosystem variety.
• Past biodiversity levels were higher than current levels and were often impacted by mass extinctions.
• Anthropogenic (human-caused) activities threaten biodiversity.
• Conservation methods include in-situ (e.g., wildlife reserves) and ex-situ (e.g., zoos).
• Reproductive isolation plays a role in the divergence of species, often due to geographic isolation.
• Adaptive radiation increases biodiversity by allowing species to exploit new niches.
• Barriers to hybridization (pre-zygotic and post-zygotic) prevent gene mixing between species.
• Hybrid species often have reduced or no fertility.

Biodiversity and Extinction

• Biodiversity exists on multiple levels (species, genetic, and ecosystem).
• Past biodiversity was often greater than present levels due to historical events.
• Anthropogenic activities like habitat destruction, pollution, and climate change negatively impact biodiversity.
• Declining species richness and unhealthy ecosystems are signs of a biodiversity crisis.

Biodiversity Conservation

• Conservation efforts can be in situ (within natural habitats) or ex situ (outside habitats, such as zoos).
• The EDGE program prioritizes evolutionarily distinct and globally endangered species.
• Rewilding ecosystems to a natural state is a growing conservation strategy.

Variation as a Defining Feature of Life

• Variation is found within and between organisms due to genetic and environmental factors.
• Sources of genetic variations include mutations and sexual reproduction.
• Variation can be discrete (e.g., blood type) or continuous (e.g., height).
• Differences within species arise from shared genetics; between species from divergent evolution.

Species and Speciation

• Morphological species concept: organisms with shared physical traits.
• Binomial nomenclature: standardized system of naming organisms with genus and species.
• Biological species concept: groups of interbreeding organisms that produce viable fertile offspring.
• Species formation (speciation) is caused by reproductive isolation.

Chromosome Numbers and Karyotyping

• Chromosome number often distinguishes species.
• Karyotype is the arrangement of chromosomes ordered by size, banding patterns, and centromere position.
• Karyograms visually represent the karyotype.
• Human sex determination is XX (female), XY (male).

Genomes and Sequencing

• Genome is an organism's complete set of genetic material.
• Gene is the unit of heredity; allele is a variation of a gene.
• Genome size does not always correlate with organism complexity.
• Applications of genome sequencing are in medicine, agriculture, and evolutionary studies.
• Ethical concerns regarding genome sequencing exist concerning privacy, discrimination, and access to genetic information.

Advanced Concepts in Species Identification

• Horizontal gene transfer is common in bacteria, complicating the biological species concept.
• DNA barcoding and dichotomous keys are methods for identifying species, commonly used in conservation and tracking biodiversity studies.

Need for Classification

• Taxonomy is the science of classification.
• Traditional classification hierarchy: domain, kingdom, phylum, class, order, family, genus, species.
• Classification simplifies study and shows relationships among organisms, and their evolutionary relationships.

Modern Challenges and Evolutionary Relationships

• Convergent evolution can produce similar traits in unrelated species, making traditional classifications challenging.
• Clade is a group of organisms with a common ancestor, using shared traits through evolution.

Cladograms and Molecular Evidence

• Molecular clock uses DNA/protein sequence differences to estimate time of evolutionary divergence.
• Cladograms show evolutionary relationships through parsimony and bioinformatics.
• DNA sequences are frequently used to create cladograms.

Reclassification and Domains of Life

• Cladistics uses molecular data (e.g., rRNA) to reassess classifications.
• Three domains are Archaea, Bacteria, and Eukarya, representing an important branch of modern (phylogenetic) classification.