IB Biology HL year 2: Unit 1B (Evolution)

Vocabulary

Review

• Species ~ A group of organisms capable of reproducing either each other to produce fertile offspring

  • Organisms have similar characteristics but if they are not capable of reproducing with each other they are considered different species

• Population ~ A population is a group of the same species in the same place at the same time.

• Genome ~ A genome includes all of the genetic information of an organism

  • It provides all of the information for the growth and development of the cell and organism

  • A genome is all of the DNA in a cell

• DNA barcodes ~ A DNA sequence that uniquely identifies each species of a living organism

  • It allows scientists to rapidly determine the biodiversity of an ecosystem

• Recessive allele ~ A type of allele that when present on its own will not affect the individual

  • b

• Dominant allele ~ An allele that produces the same phenotype whether its paired allele is identical or different

  • B

• Homozygous dominant ~ A genotype where an individual inherits two copies of a dominant gene

  • BB

• Homozygous recessive ~ An organism with two of the same recessive alleles

  • bb

• Heterozygous ~ Having different alleles for a particular trait

  • Bb

Speciation

• Speciation ~ The splitting of one species into two or more species

  • The only method for the appearance of new species

  • All species must come from an ancestor that split

  • Adds new species

  • Extinction removes species

• Allopatric speciation ~ Occurs when a species separates into two separate groups which are isolated from one another. Often called geographic isolation

• Sympatric speciation ~ Is he evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.

• Peripatric speciation ~ When small groups of individuals break off from the larger group and forma new species

• Artificial speciation ~ Occurs when humans cause a new species to develop

• Parapatric speciation ~ Occurs when a smaller population is isolated, usually at the periphery of a larger group, and becomes differentiated to the point of becoming a new species

  • Para ~ near

  • Patria ~ country

• Extinction ~

Mechanisms of evolution

• Mutation ~ A change in the DNA sequence of an organism

• Gene flow ~ Any movement of individuals, and/or the genetic material they carry, from one population to another

• Natural selection ~ The process through which populations of living organisms adapt and change

  • Variation ~ Any difference between cells, individual organisms, or groups of organisms of any species caused wither by genetic differences or by the effect of environmental factors on the expression of genetic potentials

  • Overproduction of offspring ~ When the living organisms produce more offspring than that can survive

  • Differential survival ~ Describes how animals, plants, and other living organisms manage to successfully survive changes to their environment or fail and die out

  • Reproduction ~ A biological process by which an organism reproduces an offspring that is biologically similar to the organism

  • Inheritance ~ The process of transmission of genes from parent to offspring

  • Competition ~ A set of interactions between different populations or individuals from the same population to get one or more resources from the ecosystem

• Non-random mating ~ A mating system in which at least some individuals are more or less likely to mate with individuals of a particular genotype than with individuals of other genotypes

• Genetic drift ~ The change in frequency of an existing gene variant in the population due to random chance

  • Founder effect ~ The reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population

  • Bottleneck effect ~ A phenomenon in which a population is reduced in size due to natural disasters, habitat loss, or overhunting

Evidence of evolution

• Evolution ~ The change in the heritable characteristics of a population over time

  • Only genetic traits can be changed through evolution

• Homologous structures ~The same position and structure but not necessarily the same function (from a common ancestor)

  • Show evidence of a common ancestor because they develop similarly (embryos)

  • Can have leftover traits (vestigial structures)

• Pentadactyl limb ~ most animals have some version of the pentadactyl limb

  • Penta ~ five

  • Dactyl ~ digits

• Analogous structures ~ Same function, but not ancestrally related

  • Determine by looking at development

• Vestigial structures ~ Features of an organism that are considered to have lost much or all of their original function through evolution

• Convergent evolution ~ Similar environment so they evolved to look similar

• Divergent evolution ~ One split into two and then was modified over time by natural selection

• Common ancestor ~ Ancestral organism shared by two or more descendent lineages

Types of isolation

• Geographical isolation ~ Separated by a barrier

• Temporal isolation ~ Different mating seasons or active times cause then to not reproduce

  • Flowers can flower at different times preventing reproduction

  • Animals can be active at different times

• Behavioral isolation ~ Different types of behavior can lead to no mating, often courtship ritual

Extra

• Polyploidy ~ Plants can hybridize and gain different chromosome numbers causing speciation very rapidly

  • They can self fertilize allowing them to create more

• Triploid ~ The presence of an additional set of chromosomes in the cell for a total of 69 chromosomes rather than the normal 46 chromosomes per cell

• Tetraploid ~ Having four sets of chromosomes, symbolized as 4n

• Hybridization ~ The process in which two complementary single-stranded DNA and/or RNA molecules bond together to form a double-stranded molecule

• Hybrid ~ The offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction

• Prezygotic barriers ~ A mechanism that blocks reproduction from taking place

• Postzygotic barriers ~ A mechanism that blocks reproduction after fertilization and zygote formation

• Sterile ~ Unable to produce offspring

• Hybrid inviability ~ A situation in which a mating between two individuals creates a hybrid that does not survive past the embryonic stages

• Hybrid breakdown ~ A type of reproductive failure that appears at the F2 generation of crosses between different species or subspecies

• Hybrid infertility ~ The phenomenon whereby the offspring of two closely related species are incapable of reproducing

• Niche ~ The role an organism plays in a community

• Biodiversity ~ The variety of all living things and their interactions

• Selective breeding ~ the practice of mating individuals with desired traits as a means of increasing the frequency of those traits in a population

• Adaptive radiation ~ The evolution of many diverse species from a common ancestor

Diversity of organisms

• Taxonomy ~ A science that deals with naming, describing, and classfication of all living organisms including plants

• Morphology ~ The study of the size, shape, and structure of animals, plants, and microorganisms, and of the relationships of their constituent parts

• Binomial nomenclature ~ A system of naming plants and animals in which each species is given a name consisting of two terms of which the first names the genus and the second names the species itself

• Diploid ~ the presence of two complete sets of chromosomes in an organisms cells with each parent contributing a chromosome to each pair.

• Karyogram ~ A diagram or photograph of the chromosomes of a cell, arranged in homologous pairs and in a numbered sequence

• Karyotype ~ an individuals complete set of chromosomes

• Genome sequencing ~ A laboratory method that is used to determine the entire genetic makeup of specific organism or cell type

• Genomics ~ An interdisciplinary field o science that focuses on the structure, function, evolution, mapping, and editing of genomes.

• Autosome ~ Any chromosome not considered a sex chromosome

• Sex chromosome ~ A type of chromosome involved in sex determination

• Telomere ~ A region of repetitive DNA sequences at the end of a chromosome

• Homologous chromosomes ~ Pairs of chromosomes in a diploid organism that have similar genes, although not necessarily identical

• Polymorphism ~ the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species

• Genome size ~ Genome size refers to the amount of DNA contained in a haploid genome expressed either in terms of the number of base pairs, kilobases, or megabases, or as the mass of DNA in picograms

• Asexual reproduction ~ the kind of reproduction in which it is not necessary to have two parents to produce offspring

• Horizontal gene transfer ~ the movement of genetic information between organisms, a process that includes the spread of antibiotic resistance genes among bacteria, fueling pathogen evolution

• Dichotomous key ~ An important scientific tool, used to identify different organisms, based on the organisms observable traits

Natural selection

• Paradigm ~ A distinct set of concepts or thought patterns, including theories, research methods, postulates, and standards for what constitute legitimate contributions to a field

• Paradigm shift ~ A major change in the worldview, concepts, and practices of how something works or is accomplished

• Sexual reproduction ~ The production of new organisms by the combination of genetic information of two individuals of different sexes

• Genetic variation ~ The presence of differences in sequences of genes between individual organisms of a species

• Meiosis ~ A type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes

• Crossing over ~

• Independent assortment ~

• Gametes ~

• Carrying capacity ~

• Biotic factors ~

• Abiotic factors ~

• Selection pressure ~

• Denisty independent factors ~

• Intraspecific competition ~

• Sexual selection ~

• Gene pool ~

• Neo-darwinism ~

• Genetics ~

• Stabilizing selection ~

• Directional selection ~

• Disruptive selection ~

Hardy-Weinberg Equation

• What is it used for?

  • A model for predicting allele frequencies in populations that are not evolving

• Equation

  • p² + 2pq + q²

    • p = the frequency of the dominant allele in a population

    • q = the frequency of the recessive allele in a population

    • p_² = the frequency of the homozygous dominant genotype in the population

    • 2pq = the frequency of the heterozygous genotype in a population

    • q_² = the frequency of the homozygous recessive genotype in the population

1. Identify the frequency of the homozygous recessive genotype (q_²)

2. Calculate the frequency of the recessive allele (q) by finding the square root of frequency of the homozygous recessive phenotype

3. Calculate the frequency of the dominant allele (p), by rearranging: p + q = 1 to

   p = 1 - q. Solve for p

4. Calculate the frequency of the homozygous dominant genotype, p, by calculating p^2_.

5. Calculate the frequency of the heterozygous genotype (2pq) by calculating 2pq.

• The following conditions are assumed for a population in a Hardy-Weinberg equilibrium:

  • The population is too large

  • No immigration or emigration is occurring

  • Mating is random within the population (no sexual selection)

  • No mutation are occurring in the population

  • No natural selection is occurring in the population (survival rates of phenotypes is the same for all phenotypes)

• If the allele frequencies are not maintained over generations, then it can be assumed that at east one condition is not met, and there is evolution within the population.