L2: evolution and adaptation

What is another term for clade?

Major taxonomic group

What is evolution?

Change in the gene frequencies of a population over the course of generations

Common ancestor

An organism which two or more different descendant species or groups have evolved

What changes in evolution?

The gene frequencies within a population over time

What are the mechanisms of evolutionary change?

Natural selection, mutations, genetic drift, gene flow, horizontal gene transfer

Mutation

Change in a gene which can be random or non-random

Migration/ gene flow

genes move between different populations and interbreed

Genetic drift

Gene frequencies randomly change due to chance not selection which causes alleles to disappear or become fixed

Natural selection

Organisms better adapted to their environment tend to survive and produce more offspring

Natural selection acts on

Individuals

Horizontal gene transfer

The introduction of genetic material from one organism or species to another by mechanisms other than reproduction

Conjugation

Process of horizontal gene transfer where genetic material is transferred from a donor cell to a recipient cell from direct cell to cell contact

Transformation

Process of horizontal gene transfer where a cell takes up foreign DNA from its surroundings, incorporating it into its own genome

What is a phylogeny?

A hypothesis about relationships among taxonomic groups

On a phylogenetic tree, what term refers to taxa that diverged from the same common ancestor?

Sister taxa

Rooted

Single lineage (At base) represents common ancestor

Unrooted

Show relationships but not a common ancestor

What is true about organisms that are part of the same clade?

They all evolved from a shared ancestor

Taxon

Groups of organisms (Species, family, domain…)

Clade

Any branch of lineage (Lines in the tree)

Branch point (node)

Splitting represents single lineage evolving into two clades

What are the most major categories of land plants?

bryophytes, ferns, gymnosperms, angiosperms

Where did land plants evolve from?

Freshwater Green algae

What did green algae evolve from?

Photosynthetic protists, primary endosymbiosis, and secondary symbiosis

Do terrestrial environments have different challenges than freshwater environments?

Yes

What is an adaptation?

A heritable trait that helps an organism's survival and reproduction in its present environment

What are forms of adaptations?

Behavioural, structural, chemical and physiological

What was the biggest challenge of life on land for plants?

Avoiding desiccation and getting enough water from environment

What are the four main challenges of life on land for plants?

Protection against desiccation, Physical support against gravity, movement of nutrients against gravity, protection against increased exposure to solar (UV) radiation

What are some plant adaptations to living on land?

Getting nutrients, protection against predators (Herbivores), reproduction and dispersal, competition, physical space, withstanding temperature fluctuations, harsh/ harmful soils (Salt/ metals)

What features are unique to plants?

Stomata, xylem, cuticle, phloem