Biology- Evolution/Adaptation ISP

Dr. Levy Grade 11 UO

Adaptation

A structure, behaviour, or physiological process that helps an organism survive and reproduce in a particular environment

Adaptive radiation

Evolution of a number of divergent species from a common ancestor, each species becoming adapted to occupy a different environment

Mimicry

Harmless species resemble a harmful species in coloration or structure

Phenotype

Physical appearances and behaviour (as a result of a certain gene)

Gene flow

Transfer of alleles of genes from one population to another

Mutations in gamete cells

The mutation may be passed on to succeeding generations.

Selective advantage

A genetic advantage of one organism over its competitors. Causes the organism to be favoured in terms of survival and reproduction over time (when environment changes).

Horizontal gene transfer

The process of swapping genetic material between neighbouring different bacteria

Natural selection

Process when the characteristics of a population of organisms change over many generations as individuals with certain inherited traits survive and pass traits on to offspring (survival of the fittest)

Selective pressure

Environmental conditions or forces that favor certain inherited traits over others, driving natural selection.

Artificial selection

Humans artificially select organisms for particular traits (selective breeding)

Example: domestic animals are bred for appearance- cats to be fluffier, dogs to not shed

Monoculture

Fields/growing spaces where only one variety of plant is grown

Gene banks

Contain populations of early ancestors of modern plants- our most important plants came from wild ancestors with the genes that allowed them to survive and reproduce

John Ray

1627-1705: first scientist to carry out empirical studies of the natural world, developing a classification system for plants and animals based on anatomy and physiology

Carolus Linnaeus

1707-1778: Expanded on John Ray’s idea of classification of animals and plants

Charles Darwin

1809-1882: first person to publish his theory of evolution, the idea that life had changed over long periods of time.

Microevolution

Evolution within a population

Gene flow- migration

Occurs between 2 different interbreeding populations that have different allele frequencies.

Effect: may change allele frequencies in either or both populations

Non-random mating

Individuals in a population select mates, often based on their phenotypes

Genetic drift

Random change in genetic variation from generation to generation due to chance (changes allele frequencies)

Non-random mating- inbreeding

Occurs when closely related individuals breed together

Genetic drift- the Founder Effect

Gene pool change that occurs when a few individuals start a new, isolated population. Happens frequently on islands

Genetic drift- the Bottleneck Effect

Gene pool change resulting from a rapid, severe decrease in population size (e.g., due to starvation, disease, or natural disaster), leading to a significant loss of genetic diversity

Stabilizing selection

Favours an average phenotype and acts against extreme variants of the phenotype (average size/colour/shape/etc is best, not too big/small/bright/etc)

Directional selection

Favours the phenotypes at one extreme over the other. i.e- big or small is favoured, not average, and not both- ONLY ONE extreme is favoured

Disruptive selection

Favours either extreme over intermediate (average)

Speciation

Formation of new species from existing species

Reproductive isolating mechanisms

Pre-zygotic and post-zygotic

Pre-zygotic

Before fertilization

Post-zygotic

After fertilization

Pre-zygotic isolating mechanisms

Prevention of mating and prevention of fertilization

Prevention of mating

Don’t mate

Prevention of fertilization

Mate but don’t get fertilized

Prevention of mating categories

Behavioural isolation, temporal isolation, and ecological/habitat isolation

Behavioural isolation

Different mating signals

Temporal isolation

Different mating times (season)

Ecological/habitat isolation

Different habitats

Prevention of fertilization categories

Mechanical isolation and gametic isolation

Mechanical isolation

Mate but not physically possible to become fertilized

Gametic isolation

Mate but sperm and egg don’t meet

Post-zygotic isolating mechanism

Prevention of hybrids

Prevention of Hybrids

Become fertilized but something goes wrong

Prevention of hybrids categories

Zygotic mortality, hybrid inviability, and hybrid infertility

Zygotic mortality

Zygote dies before development

Hybrid inviability

Hybrid develops, but is weak

Hybrid infertility

Hybrid is normal, but cannot reproduce