BIO120 UOFT TEST 1

Biology

The study of life

Charles Darwin

English natural scientist who formulated a theory of evolution by natural selection (1809-1882)

Wallace

English naturalist who formulated a concept of evolution that resembled Charles Darwin's (1823-1913)

William Paley

Argued that design in nature is evidence of God's existence

Argument of Design

The universe works so perfectly that it must have a designer.

Lamarck

French naturalist who proposed that evolution resulted from the inheritance of acquired characteristics (1744-1829)

Weissman

Disproves Lamarck with germ plasm theory

germ-plasm theory

cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

Genotype

An organism's genetic makeup, or allele combinations.

Mendelian Genetics

The pattern of inheriting characteristics that follows the laws formulated by Gregor Mendel

Uniformitarianism

A principle that geologic processes that occurred in the past can be explained by current geologic processes

antibiotic resistance

Resistance evolving rapidly in many species of prokaryotes due to overuse of antibiotics, especially in agriculture.

Microevolution

Evolutionary change below the species level; change in the allele frequencies in a population over generations. (eg. natural selection)

Macroevolution

Evolutionary change above the species level, taking lots of time.

Mutation

A random error in gene replication that leads to a change

Adaptation (noun)

A feature or behavior that helps animals survive.

Adapt (verb)

Evolutionary process that leads to the origin of adaptations

The Theory of Evolution (2 points)

1) Living things change gradually over time

2) Adaptations have risen through natural selection

common ancestry

A group of organisms share common descent if they have a common ancestor

Homozygosity

An organism that has two identical alleles for a trait

Heterozygosity

having different alleles at a gene locus

gene locus

Location of a gene on a chromosome

Phylogeny

Evolutionary history of a species

phylogenic tree/cladogram

a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor.

4 approaches to studying evolutionary biology

1) Observational

2) Theoretical

3) Comparative

4) Experimental

selfing or self fertilization

the fertilization of plants and some invertebrate animals by their own pollen or sperm rather than that of another individual.

scientific theories...

have testable and falsifiable hypotheses

Gradualism

The theory that evolution occurs slowly but steadily

Species

A group of similar organisms that can breed and produce fertile offspring.

Variation

Any difference between individuals of a population

Heredity

Passing of traits from parents to offspring. Progeny resemble their parents more than unrelated individuals.

Fitness

Ability of an organism to survive and reproduce in its environment. Some forms are more successful than others in a given environment.

4 Main Evidences for Evolution

1) geology

2) homology (eg. vestigial limbs, similar genes, embryonic similarities showing vestigial organs)

3) biogeography (geographically close organisms resemble each other)

4) domestication (artificial selection performing the same thing as natural selection)

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

mutation-selection balance

reintroduces less fit genes to maintain variation

Speciation

Formation of new species

Genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

Genetic Drift: Bottleneck Effect

The mechanism of microevolution that involves a loss of variety (alleles) after an event that greatly reduces the size of the population. (can lead to extinction)

Genetic Drift: Founder Effect

Occurs when a few individuals become isolated from a larger population; can affect allele frequencies in a population

Endemism

A state in which species are restricted to a single region; they are ONLY found there

descent with modification

principle that each living species has descended, with changes, from other species over time

neutral mutation

a mutation that has no effect on survival or reproduction

Beneficial Mutation

any change to the genetic code that results in noticeable physiological changes that are of benefit to the organism

Deleterious mutation

Genetic changes that are harmful to an organism; weakly up to lethal

Environment can affect the number of mutations, but not the...

chance of mutation.

point mutation

Gene mutation involving changes in one or a few nucleotides.

insertion mutation

a mutation in which one or more nucleotides are added to a gene

Changes in repeat number

ATGATGATGATG -> ATGATGATGATGATG

chromosomal rearrangements

deletion, duplication, inversion, translocation. Large mutations

Diploid

(genetics) an organism or cell having two sets of chromosomes or twice the haploid number

G6PD deficiency

2 amino acid replacements, causes anemia but gives malaria resistance; higher in populations around the tropics

Phenotype

An organism's physical appearance, or visible traits.

Preformationism

spermist and ovists believed only one parent contributed to inheritance.

theory of blending inheritance

each parent contributed factors that were blended in their offspring (blue + yellow = green)

Mendel's Law of Segregation

the two copies of a gene segregate from each other during transmission from parent to offspring

Alleles

Different forms of a gene

Gamete

a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

Zygote

the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo

Genome

All the genetic information in an organism; all of an organism's chromosomes.

Polyphenism

a trait for which multiple, discrete phenotypes can arise from a single genotype depending on environmental circumstances

Polymorphism

(biology) the existence of two or more forms of individuals within the same animal species (independent of sex differences). Proportion of gene loci that have 2 or more alleles in the population.

discrete traits

Characteristics that are qualitatively different from each other

continuous traits

Continuous traits are those that can exist in a range (height, age, skin color, etc.)

particulate inheritance

the concept of heredity based on the transmission of genes (alleles) according to Mendelian principles

population genetics

Study of allele frequency distribution and change under the influence of evolutionary processes.

Recombination

the genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division. creates new combinations of mutations. The mixing of genes through sex

random genetic drift

acts to decrease genetic variation, affects small populations most

purifying selection (negative selection)

Selection that lowers the frequency of or even eliminates deleterious alleles.

directional selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals. Mutations that increase fitness can become fixed.

selection favouring diversity

increases/retains genetic variation in populations, maintains diversity

Migration (gene flow)

movement of genes between populations, can make two unlike populations more genetically similar

Selection maintaining variation (balancing selection)

suite of adaptive forces that maintain genetic variation for longer than expected by random chance. Heterozygote advantage, frequency dependent selection, fitness varies in space and time

artificial selection

Breeding organisms with specific traits in order to produce offspring with identical traits.

monomorphic gene

a gene having a single form

Allozymes

different allelic forms of the same protein

Neutral Theory

The hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection.

schools of evolutionary thought

Classical school vs. Balance school, two schools that differed in their predictions on how much genetic variation occurs in natural populations

Electrophoresis

A process where DNA fragments are separated according to size using electrical charges: helped to answer how much of genes were variable

reproductive modes

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

asexual reproduction

Process by which a single parent reproduces by itself; product is clones; maintains favorable combinations of alleles

Clones

Genetically identical cells or individuals.

Paradox of sex

asexual reproduction is much more efficient than sexual reproduction, and yet sexual reproduction brings genetic diversity

Transmission Bias

A situation in which the alleles of the parent organisms are not equally represented in their offsprings.

lottery models

emphasize the role of chance in maintaining species diversity

Tangled Bank Hypothesis

Variety of offspring also helps to eliminate competition for resources; genetically diverse off spring are able to extract more food from their environment than genetically identical clones.

Red Queen Hypothesis

Sexual selection allows hosts to evolve at a rate that counters the rapid evolution of parasites. Species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species.

asexual species often appears...

at the end of the phylogenetic tree; they have a low chance of long term evolutionary persistence due to accumulation of deleterious mutations

spatial heterogeneity

the variation in space in distribution of a point pattern, or variation of a qualitative or quantitative value of a surface pattern

parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs; more common in invertabrates

clonal propagation

Cuttings from plant are used to regenerate plants; few species are exclusively asexual

Outbreeding

the process of mating less closely related individuals when compared to the average of the population

inbreeding

A selective breeding method in which two individuals with identical or similar sets of alleles are crossed.

outcrossing

mating with someone else, fusion of gametes between 2 parents

selfing

most extreme form of inbreeding but not asexual reproduction, fusion of gametes from one parent

extra-pair copulations

when an individual that has a social bond with a mate also breeds with other individuals (no monogamy)

inbreeding depression

when individuals with similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to survive and reproduce: reduction in fitness, lower viability, lower fertility

hermaprodite

an organism that has both male and female reproductive organs

sexual dimorphism

Differences in physical characteristics between males and females of the same species.