Theme 1 - Phylogeny and Evolution

Biodiversity

The variety of life that exists on Earth.

Genetic Diversity

The variation of genetic information that exists both within and across populations of a species.

Population

Group of individuals of the same species that live in the same area and breed with one another.

Species Diversity

The amount of diversity of different species that exists within a certain region.

Ecosystems

Regions where species interact with one another.

Ecosystem Diversity

The amount of different types of habitats that exist within a certain area and the different ecological interactions that occur within these habitats.

Provisioning Services

Products that humans obtain directly from nature, such as medicine, food and raw materials.

What is the risk of loss of species in an ecosystem?

Loss of species leads to a loss in genetic diversity, which is important for species to survive, as a variety increases chance of survival.

Regulating Services

Benefits that humans receive from ecosystems apart from raw materials, this can include water and air purification.

Supporting Services

Services offered by an ecosystem that are important for the functionality of the biosphere.

Cultural Services

Services that humans obtain from ecosystems that don’t constitute raw materials, such as recreational services.

Extinction

When not a single member of a species is living on Earth.

Extant Species

Members of the species are still alive on Earth.

Extirpation

When a species has died out in a specific area, however populations still exist in other regions.

What is the impact of human activity on an ecosystem?

Human activities, such as pollution and deforestation are decreasing ecosystem diversity

Habitat Loss

Human activities that fragment or completely remove a habitat.

Introduced Species

Species that are brought to a new region that is outside of their native range.

Invasive Species

Introduced species that cause harm to the new environment they were introduced to.

Overexploitation

Overharvesting of plants and animals at unsustainable levels that causes for their population to decline or for them to become extinct.

What impact does Climate Change have on biodiversity?

Climate change is causing changes to the weather, which then impacts the ecosystems of different areas. This is then causing for certain ecosystems to expand and others to shrink or move, species must them either adapt, migrate or they die. Many will die as of the difficulty to expand their range and the inability to adapt in time, it also increases disease.

Causation

One variable directly affects another.

Taxonomy

Scientific discipline concerned with naming and classifying organisms.

Nomenclature

The rules for naming things.

What are problems with common names?

1. Different common names for the same species

2. Same name fro different species

3. Common names often imply false relationships

Hierarchical Classification

Classifying species into groups based off of this common structures and features.

Binomial Nomenclature

Unique two-part scientific names for species. (Genus and specific epithet)

Taxon/Taxa

A taxonomic rank at any level of a hierarchical classification.

What are the three domains?

1. Bacteria

2. Archaea

3. Eukarya

Systematics

Theory and method of classifying organisms based off of their evolutionary relationships and history. Focuses on why organisms should be classified in certain ways.

Phylogenetic Tree

A diagram that provides hypotheses for the evolutionary relationships between organisms.

What are the purposes of phylogenetic trees?

• Organize biodiversity

• Visualize evolution

• Structure classification

• Guide research

• Connect different fields of bio

  • Enable predictions

Morphological Data

Data of physical traits of organisms including size, shape, structure.

Molecular Data

Comparing DNA/RNA sequences in order to predict relationships and phylogenies, however can only be used for extant species.

Branch Point (of a Phylogenetic Tree)

Representative of a common ancestor of taxa.

Sister Taxa

Two descendants that split from the same branch point and originate from the same common ancestor.

Basal Taxon

A taxon that diverges earlier from the other taxa and originates from the common ancestor of the entire phylogeny.

Polytomy

Branch where more than two group emerge from.

Clades

Groups that include the common ancestor and all of that ancestor’s decendants.

Cladograms

Diagrams that show evolutionary relationships, where the position and branch length are unimportant.

Phylograms

Diagrams that depict evolutionary relationships, where the branch length represents evolutionary change for that species.

What do phylogenetic polytomies mean?

• Lack of data to determine relationships

  • Rapid speciation

Homology

Similarity between organisms due to a shared ancestor.

Analogy

Similarity between organisms due to adaptations to their environment.

Convergent Environment

When unrelated organisms evolve to possess similar traits due in response to their environment.

Trait Complexity

The more complex two similar structures are the less likely that the organisms are unrelated.

Ingroup

The group of taxa whose evolutionary relationships are being studied.

Outgroup

One or more taxa related to the ingroup, used as a point of reference for the studied taxa.

Characters

Anatomical, physiological or molecular features used to compare taxa.

Character States

The observed characters of an organism and their taxon that helps identify evolutionary changes.

Cladistics

A method that uses homologous characters in order to determine evolutionary relationships of a taxa, this method is based on shared derived characters.

Monophyletic

A group of taxa that include the common ancestor and all of its decendants.

Paraphyletic

A grouping that includes a common ancestor, but not all of the decendants.

Polyphyletic

Grouping of distantly related taxa, not including common ancestors.

What are the causes of polyphyletic grouping?

• Incorrect taxonomic classification

• Lack of data/fossil records

  • Multiple common ancestors/hybrid speciation

Shared Derived Characters

Traits that have evolved in a recent common ancestor, therefore only members of that clade possess that trait.

Shared Ancestral Characters

Traits shared by taxa of a clade, thats also possessed by taxa of earlier clades.

Maximum Parsimony

A method to find the most likely evolutionary tree by selecting trees that have the fewest mutations/evolutionary changes.

Maximum Likelihood

A method to find the most likely evolutionary tree that uses statistics to find the probability of evolutionary changes.

Theory of Evolution

Gradual change and diversification of species over time and the appearance of new species.

Natural Selection

Process where organisms with more advantageous traits that aid in their survival are more likely to pass those traits onto their offspring, which leads to gradual changes overtime in a population.

Adaptations

Inherited traits that improve an organism’s survival in a specific environment.

Strata

Sedimentary rock that is formed in layers.

Catastrophism

A theory made by Georges Cuvier that each boundary between strata corresponds to a catastrophic event.

What was Jean-Baptiste Lamarck’s theory?

Species evolved through the inheritance of traits that an organism develops throughout their lifetime (change occurs within one generation).

What are Darwin’s two main points?

1. Species show evidence of evolution from a common ancestor

2. Natural Selection is the mechanism for evolution

Genetic Diversity

The genetic variation within and between populations of a species.

Genotype

Genetic makeup of an organisms.

Phenotype

The observable traits that occur due to an organism’s genotype and environmental factors.

Phenotypic Variation

The variability in phenotypes that exist in a population.

Selective Agents

Environmental factors that have an affect on the survival of organisms.

Selective Pressure

A selective agent that consistently causes a difference in the survival of the population or species. Directly related to natural selection.

Evidence for Evolution

1. Direct observations of evolutionary change

2. Homologies

3. Fossil records

4. Biogeography

How do direct observations of evolutionary change provide evidence for evolution?

By observing the taxa of species that reproduce very quickly and therefore can have more rapid change occur to a population.

Artificial Selection

When humans induce evolutionary change and favour a specific trait in a group over others.

Morphological Homologies

Physical resemblances representing variations on a structural theme that originates from a common ancestor.

Homologous Embryonic Structures

How many vertebrates have very similar structures during developement.

Vestigial Structures

Traits that an organism inherited from a common ancestor that are no longer in use.

Molecular Homologies

How all living organisms share genetic code that suggests that they all descend from a common ancestor.

How does the fossil record provide evidence for evolution?

It provides evidence for extinct of species, origin of new groups and long-term evolutionary changes within groups.

Transitional Fossils

Fossils that document the existence of intermediate forms that appear to be ancestors of living species.

Chronological Sequences

The order in which different groups of taxa appear in the fossil record aligns with their evolutionary relationships.

Biogeography

Study of how species are distributed across the globe, provides strong support for evolution by showing how geographic isolation and evironmental factors shape species diversity.

Isolated Species

Species that are closely related to those on nearby continents but have evolved distinct traits due to geographic isolation.

Adaptive Radiation

Group of taxa diversify from a common ancestor due to selective pressures.

Endemic Species

Species that are only found in a specific area and are not found elsewhere on Earth.

How do continental patterns of species distribution reflect evolutionary histories?

Geographical distribution of living and fossil species assists in the reconstruction of evolutionary history.

Microevolution

The change in allele frequencies in populations over generations.

Allele

Different forms of a gene, corresponding to different DNA sequences in each form.

Gene Pool

Range of available genes within a population.

What is the advantage of genetic variation?

Enables a population to adapt to the environment through natural selection.

Mutations

Changes in an individual’s DNA that occurs randomly and gives rise to new alleles.

Chromosomal Mutations

Larger mutations that delete, disrupt or rearrange the DNA sequence of a chromosome.

Whole-Genome Duplication

The process by which genomes are doubled, supplying genetic material and increasing genome complexity.

Recombination

During meiosis when homologous chromosomes are shuffled creating new allele combinations.

Non-Adaptive Evolution

Changes in allele frequency that do not cause for a population to evolve or become more adapted to their environment.

What causes non-adaptive evolution?

Gene flow, genetic drift, mutations and recombination.

What is the only cause of adaptive evolution?

Natural selection

Relative Fitness

The contribution that an individual’s genes make to the gene pool of the next generation.

Directional Selection

Natural selection that favours individuals thats different formt he current mean in one direction.

Disruptive Selection

Individuals at extreme ends of the phenotypic range have higher fitness.