SBI3U1 - Evolution

Evolution

Significant changes in the DNA of a species or population over time; process by which modern organisms have descended from ancient ones

Uniformitarianism - Lyell

Supports a theory that geological change is slow and gradual; connects the idea of gradual change to living organisms

Scientific theory

Well-supported testable explanation of phenomena

Mutations

Permanent changes in DNA

Fitness

The ability of an organism to reproduce and survive in its environment

Adaptation (advantageous variation)

Organisms must overcome environmental challenges in order to survive; structure, behaviour, or physiological process that helps an organism survive and reproduce in a certain environment

Selective pressures

Selecting for or against a trait; the evolutionary force that causes a particular phenotype to be either more favourable or unfavourable based on environmental conditions

Interspecific competition

Individuals of different species compete for the same limited resources within an ecosystem

Intraspecific competition

Individuals of the same species compete for resources like food, water and mates

Homologous structures

Different function, same development; share a common ancestry under different selective pressures

Analogous structures

Same function, different development; different common ancestors under same selective pressures; no indication of an evolutionary relationship

Divergent evolution

Accumulation of differences of similar features of a common ancestor; homologous structures

Convergent evolution

Independent evolution of similar features from different lineages; analogous structures

Sexual dimorphism

The striking differences between the appearance of males and females of the same species

Stabilizing selection

The most common phenotypes have higher fitness and become more common

Directional selection

Individuals at one end of the phenotype have higher fitness and become more common

Disruptive selection

Individuals at both phenotypic extremes have higher fitness and become more common

Vestigial structures

Non-functioning structures that are present in reduced form

Embryonic homologies

When there are more similarities between embryos during embryonic development indicates an evolutionary relationship

Gene flow

Movement of alleles from one population to another; “Migration”

Genetic drift

Change in frequency of alleles due to a random event in a small population

Natural selection

Organisms that are most suited to the environment survive and reproduce and are able to pass on DNA which will then increase the alleles in the overall population

Microevolution

Change in gene frequency and phenotypes through a short period of time within populations/species

Macroevolution

Change in gene frequency and phenotypes over a long period of time and at or above species level

Sympatric speciation

Occurs when a population becomes reproductively isolated; not geographically isolated; can’t interbreed due to other factors and may adapt to the use of different resources in the same

Reproductive isolation

Not able to interbreed and produce viable offspring

Allopatric speciation

Occurs when a population is split into two or more isolated groups by a geographical barrier; eventually the two groups are unable to interbreed if brought back together

Transformation

New species are a result of accumulated changes over time; one species is transformed into another

Divergence

Branches into two or more species that diverged from a common ancestor; increase biological diversity and number of species

Adaptive radiation

One species diverges in two three or more; particularly when new resources of niches become available

Coevolution

One species evolves in response to the evolution of another species

Mimicry

The close external resemblance of an animal or plant (or part of one) to another animal, plant, or inanimate object.

Gradualism

Big changes occur through the accumulation of small changes; change is slow and steady → Lyell

Punctuated equilibrium

Evolutionary history consists of long periods of equilibrium and punctuated periods of divergence due to a large environmental change or geographical isolation

Pseudogenes

Genes that have undergone mutations and no longer serve a purpose - like vestigial structures

Monoculture

Is a type of artificial selection used in agriculture where a large area has only one type of plant resulting in little genetic diversity

Urbanization

Human activities have had an immense impact on speciation, population decline, and extinction as they essentially isolate populations

Ecological isolation

Species occupy different habitats so they won't breed

Temporal isolation

Species have different times for mating seasons

Behavioural isolation

Species have different signals to attract mates

Mechanical isolation

Species have different reproductive organs that “don’t fit”

Gametic Isolation

Gametes will only recognize each other's molecular markers

Zygotic Mortality

Zygote can’t develop

Hybrid inviability

Fertilization occurs, but the embryo doesn’t fully develop

Hybrid infertility

Hybrid cannot reproduce

Selective advantage

A genetic advantage that improves organisms chance of survival