BIO 120 Barrett Test 1 Terms (UofT, 1st Year Life Science)

Theory of Evolution

The central unifying concept of biology. One of the most influential concepts of Western thought. Living things change gradually from one form into another over time. Challenges view of special creation which is direct creation of all things in effectively their present form.

Microevolution

Evolutionary mechanisms (Doing actual experiments and tests for things that are still on-going)

Determining the ecological and genetic mechanisms responsible for evolutionary change

Involve population-level studies of natural selection, adaptation and speciation using diverse organisms

Testing of theoretical models by experiments in the lab and field

Macroevolution

- Evolutionary history (Discovering things through procedures to come up with new data)

Determining evolutionary relationships of organisms in terms of common ancestry-phylogenetics

Affinities of organisms provide a basis for classification -- taxonomy and systematics

Comparative data from many sources e.g., biogeography, paleontology, morphology, development and genomics

Approaches and Assumptions in evolutionary biology

- Observational, experimental, or theoretical.

Biodiversity

The variety of life on Earth; the number and kinds of living organism in a given area

Adaptation

- has two meanings; state or processes

Any trait that contributes to fitness by making an organism better able to survive or reproduce in a given environment

The evolutionary process that leads to the origin and maintenance of such traits

Founder Events

Introduction of a small number of individuals that possess a small sample of the genetic diversity of the source population

Clonal Propagation

Asexual reproduction by multiplication of genetically identical copies of individual plants. Reproduction clonally meaning that 100% of DNA is passed down from the parent.

Bird pollination

Birds hover or perch when nectar feeding.

Perch function

A way for birds to pollinate plants. The plant provides a long stem for them to stand on while bending over to pollinate the plants

Reproductive success

The plant got a perch through adaption to promote plant reproduction which has succeeded

Inheritance of acquired characters

Hypothesis that physiological changes acquired over the life of an organism may be transmitted to offspring.

Germ plasm theory

Inheritance only comes from germ cells (gametes not somatic cells). So only gametes can pass info to gametes, no exchange from soma to gametes.

Publication of "Origin of Species"

Wrote but did not publish an essay on natural selection which lead to the work on a natural selection book. Two key components from the book: All organisms have descended with modification from common ancestors AND The major agent of modification is natural selection operating on variation among individuals. Published in 1859

Gradualism

- Present day geological process can explain the history of the earth

Descent with modification - All organisms have descended from common ancestors. Meaning that the modification is natural selection operating on variation among individuals

Natural selection

- Explains apparent design in nature by a purely materialistic process that doesn't require creation or guidance by supernatural forces (leads to producing organisms that can adapt to that habitat and way of life).

Requirements for evolution

- Variation: Variation among individuals in a population

Heredity: Progeny resemble their parents more than unrelated individuals

Selection: Some forms better at surviving and breeding than others in a given environment

Creation "science"

It is not supported by any empirical observations. It does not infer its principles from observations, as does all science. Its assumptions lead to no testable or falsifiable hypotheses.

Tropical Ecosystems

Very high species diversity of plant and animal groups compared with temperate zone

Many more biotic interactions, especially coevolved mutualisms between plants and animals

Year-round warmth results in rapid growth of insect and microbial populations. Pest and disease pressures on plants more intense.

Largely evergreen

Temperate Ecosystems

Not evergreen

Wind pollinated

Biotic Factor

Affect plant/animal life more due to the fact that since they are living things they may help them in more ways than an abiotic factor can.

Abiotic Factors

Usually benefit humans as they can provide some sort of intel to past lives.

Animal pollination

Animals are more effective pollinators in tropical areas

Mutualism

When two things live off of each other by defending the other so that they both stay alive while trying to survive.

Pest pressure

Year round warmth results in rapid growth of insect and microbial populations

Plant herbivory

Plants that are affected by other animals eating it or picking it apart affecting its overall appearance

Field experiments

Completing some sort of hypothesis/proposal in that species habitat rather than bringing them to a lab.

Epiphytes

Plants that grow on other trees.

Convergent evolution

Epiphytic life form evolving independently in may unrelated families

Long-distance dispersal

The species can travel long distances to inhabit a new area.

Adaptive radiation

The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage as a result from speciation.

Flightless Birds

Birds that have wings because they used to be able to fly but have now adapted to use their wings for other things

Sexual dimorphism

A characteristic/trait that differs in male and females.

Endemism

Species that are restricted to a particular geographical region or habitat

Geographical isolation

Species that are separated from exchanging genetic material with other organisms of the same species.

Galapagos islands

15 main islands of volcanic origin. Flora and fauna colonized by species capable of long-distance dispersal from South America mainland. Distinct races and species on different islands provide evidence of early stages of speciation. Darwin spent 5 weeks here and formed his foundation on the theory of evolution

Patagonia

Abiotic factors dominate and landscapes are geologically young. Abrupt treeline governed by abiotic factors

Australia

Distinct flora and fauna with high levels of endemism and many unique adaptations. Biological uniqueness due to long history of isolation from other land masses.

Genotype

Genetic constitution of an organism --used in relation to a particular gene or gene combinations

Phenotype

The organism as observed -- used when discussing a trait or a feature of an organism that varies

Genome

The entire organism's DNA including both genes and noncoding regions

DNA

Deoxyribonucleic acid, molecule that carries genetic information

Gene

The functional unit of inheritance. A unit of hereditary information located on the chromosomes consisting of DNA. A DNA sequence composed of codons essential for a specific biological function.

Allele

2 copies of a gene

Mutation

Stable change in DNA sequence resulting in a change of genotype. Occurs at a very low but variable rate in all organisms. Unstoppable phenomenon, environmental insults can also affect mutation rate.

Recombination

A type of assortment during meiosis that creates genetic diversity

Types of mutation

- Point mutation: Replaces a single letter in a codon

Insertion/deletions: Removes or adds an extra DNA into the sequence

Changes in repeat number: If DNA is repetitive and a certain number of codes goes there, this mutation will add or remove and extra codon.

Chromosomal Rearrangement: Flipping of the DNA sequence

Transposable genetic elements

- Sequences of DNA that move, or jump from one location to another.

Fitness effects of mutations

Depends on mates, but can affect reproduction. Random. Depends on environment

Blending and particulate inheritance

Blending inheritance shows that the offspring getting a cross of the intermediate phenotype. Particulate inheritance is inheritance determined by discrete particles.

Discrete Trait

simply inherited by 1 or 2 genes (major genes; Mendelian genetics)

Continuous Traits

Complex inheritance by many genes (polygenes) of small effect (quantitative genetics)

Genetic polymorphism

The occurrence of two or more discrete forms of a species in the same locality in such proportions that the rarest cannot be maintained by mutation alone.

Quantitative inheritance

When many factors combine to result in a distinctive trait.

Fisher's fundamental theorem

The rate of increase in fitness of a population at any time is equal to its genetic variance in fitness at that time.

Polymorphism

Proportion of gene loci that are polymorphic

Heterozygosity

Average frequency of heterozygous individuals per gene locus

Processes affecting genetic diversity

Genetic drift, natural selection

Mechanism maintaining diversity

Mutation because of ultimate source of genetic variation and caused by random errors during replication. Recombination, some parts of natural selection.

Artificial selection on quantitative traits

Selection experiments in different groups of organisms. Involves controlled breeding and selection of individuals for many generations.

Classical schools

Lab mutants, high homozygosity, low polymorphism, wild type is best genotype; purifying selection reduces diversity

Balance

natural populations, low homozygosity, high polymorphism, no best or ideal genotype; balancing selection favours diversity.

Enzyme electrophoresis

Provided a way to ask "what proportion of genes are variable?" measuring diversity.

DNA sequence diversity

Showed how different alleles/genes showed up

SNP's

Single nucleotide polymorphisms can be measured for thousands of genes

Genome sequencing

SNP's in lines that vary from person to person.

Reproductive modes

Reproductive system: asexual and sexual Sexual system: dioecious and hermaphrodite

Mating System

cross-fertilization and self-fertilization

Paradox of the evolution of sex

Main question "What are the benefits?"

Costs of sex

Time & energy to find and attract mates, increased energetic costs, risk of predation and infection, cost of producing males, 50% less genetic transmission, break up of adaptive genes combinations.

Transmission bias

A sexual female contributes only 50% of her genes to the next generation compared with an asexual female, who contributes 100% (favours asexuals)

Asexuality

Producing asexually means to give 100% of their genes.

Tangled bank and Red Queen hypothesis

Spatially heterogeneous environments.

Temporally heterogeneous environments

Clonal Reproduction

The offspring being the exact copy of the parent.

Parthenogenesis

Sporadically distributed across the animal kingdom, more common in invertebrates but rare in vertebrates

Bdelloid Rotifers

A case of ancient asexuality where no male has ever been found but diversification has led to more than 300 spp.

Hermaphroditism

Having male and female reproductive organs, especially flowers, on different individuals.

Inbreeding

mates more closely related than random

Outbreeding

mates less closely related than random

Genetic consequences of inbreeding

Genotypic frequencies changed, allele frequencies unchanged, heterozygosity reduced by 50% per generation with self-fertilization, Homozygosity for deleterious recessive alleles results in inbreeding depression.

Inbreeding depression

The reduction in fitness of inbred offspring in comparison with outcrossed offspring. Manifested by reductions in viability (survival) and fertility. Strong inbreeding depression favours survival of outbred offspring thus favouring outcrossed mating systems.

Evolution of selfing

Species/plants that produce their own sort of pollination without needing the help of something else.

Baker's Law automatic selection

Long-distance dispersal favours selfing forms because a single individual can start a colony without mates or pollinators.

Geographic variation

How much of the observed variation among individuals is genetic in origin? Does the variation contribute to fitness differences among individuals?

Population Differentiation

What proportion of all genetic variation in a species is due to differences between populations? Are some loci or traits more differentiated than the genome-wide average?

Gene flow

The movement of genes from one population to another

Stochastic processes

Mutation, recombination, gene flow, genetic drift

Genetic drift

Stochastic (random) changes in allele frequency due to random variation in fecundity and mortality.

Genetic markers

A known location on a chromosome that can be used to identify a species or individuals.

Measuring gene flow

Distinguish potential vs actual, distinguish gamete vs individual, use experimental approaches, use neutral genetic markers

Transgenic escape

Gene transfer by recombinant DNA technology

Tristyly and its inheritance

Mating only between morphs. Dominant allele decides what traits it gets. 1:1:1 morph frequencies at equilibrium

Frequency-dependent mating

When mating occurs in one area with on species.

Equilibrium morph frequencies

Frequency-dependent mating and genetic drift in tristylous populations

Evolution of selfing from outcrossing

Joint action of genetic drift and natural selection.

Types of Selection on quantitative traits

In stabilizing traits, the maximum is favoured. In directional traits, the right side is favoured. In disruptive traits, the two end sides (minimums) are favoured.

Measurement and response to selection

In birth weight for example, the infant mortality is lower when the weight is higher/in between 5-10 pounds.

Evolution of cyanide resistance

Found at low frequency in populations. Resistance spreads through the population when selection is imposed by cyanide fumigation. This process serves as model for the evolution of many forms of resistance, e.g., antibiotics, insecticides, herbicides.

Mechanisms of selection

Measurements of selection demonstrating fitness differences and evolutionary change in traits.

Industrial Melanism

When pollution was high in areas, more moths with a certain allele were found there due to their camouflaging.