IB HL Bio Unit 2 - Evolution terms

Variation

Concept of Natural Selection - organisms of the same species have genetic variations (from mutations) that are inherited

Darwin’s Pigeons

Darwin noted that pigeon breeds were morphologically different but shared common ancestor from selective breeding

proved selective breeding is more rapid, but both select favorable characteristics over generations

Population

a group of organisms of the same species living in the same area at the same time

Sexual Reproduction

the production of new organisms by the combination of genetic information of two individuals of different sexes of the same species.

endless variation possibilities w/ unique crossing of homologous chromosomes

Asexual Reproduction

the production of new organisms without the need of a second parent - one organism self-fertilizes to produce offspring

Linnaeus

Developed most of classification system - NOT THE IDEA OF CLASSIFICATION

Morphological Species concept

Species distinguished by morphological (physical) differences - NOT ACCURATE

Biological Species concept

a group of potentially interbreeding individuals that produce fertile and viable offspring.

does NOT apply to asexually reproducing organisms

Bacterial conjugation

transfer of genes between cells via plasmids, helps with antibiotic resistance

Binomial Nomenclature

Uses both genus and species names, all italicized with only first letter of genus capitalized.

ex. Homo sapiens

Genome

Complete set of genes in an organism. Genome size dependent on amount of DNA in haploid cell, does not indicate complexity of organism

Single-nucleotide polymorphisms (SNPs)

replacement of a single nucleotide with another = genetic diversity/variations

Chromosome number

total count of chromosomes in a cell, coming from parents and comprised of autosomes and one pair of sex chromosomes

Haploid

One set of chromosomes

Diploid

Two sets of chromosomes

Human Chromosome number

46 chromosomes (diploid)

Chimpanzee Chromosome number

48 chromosomes (diploid)

Chimpanzees + Bonobos

Ex. of Allopatric speciation - chimps and bonobos shared common ancestor separated by congo river = speciation developing bonobos south of the river and chimps in the rest. Plentiful resources south of river = cooperative bonobos and little resources elsewhere = aggressive chimps

Chromosome fusion

ex. Chimpanzee chromosomes 12 and 13 fused to make human chromosome 2

Karyogram

Images of real chromosomes by a photomicrograph arranged in size order and numbered

Karyotype

Describes Karyogram by stating number of chromosomes, the sex, and any abnormalities

Aneuploidy

One or more extra or missing chromosomes in a cell or organism

Monosomy

Absence of one member in a chromosomal pair

Trisomy

Presence of an extra chromosome in one or all pairs

ex. Trisomy 21

Trisomy 21 (Down Syndrome)

An additional chromosome on pair 21

XX

Female sex chromosomes (still homologous)

XY

Male sex chromosomes (not homologous)

Homologous chromosomes

Two chromosomes in a pair - one from mother and one from father. Same genes in same order, but possibly different alleles due to slight variations

Autosomes

Any chromosome that is NOT a sex chromosome

Sex Chromosomes (why aren’t they homologous chromosomes?)

Chromosomes that determine the sex of an organism (XX=female XY=male)

Locus/Loci

location of Genome in chromosome

Dichotomous Key

A tool to identify organisms through a series of yes/no questions

Taxon/Taxa

Level of classification

ex. Kingdom

Taxonomy

Linnaeus’s scientific classification system originally based on morphological similarities

Domain

Based on rRNA in 3 categories; Eubacteria, Archea, Eukarya

Carl Woese

Developed 3 Domain system based on rRNA

Bacteria

Kingdom Eubacteria

Archaea

Kingdom Archaebacteria

Eukarya

Kingdoms Animalia, Plantae, Fungi, Protista

Kingdom

Archaebacteria, Eubacteria, Animalia, Plantae, Fungi, Protista

Eubacteria

Domain: Bacteria

Number of Cells: unicellular prokaryotes

Presence/Composition of Cell Wall: cell walls of peptidoglycen

Mode of Nutrition: some photosynthetic, some heterotrophic

Reproduction: asexual except bacterial conjugation

Motility: motile if flagella/pili are present

Environment/Habitat: virtually everywhere

Example: E. coli

Archaebacteria

Domain: Archaea

Number of Cells: unicellular prokaryotes

Presence/Composition of Cell Wall: cell walls NOT MADE OF PEPTIDOGLYCAN (defines them as archaea)

Mode of Nutrition: chemosynthetic (hydrothermal vents) or heterotrophic

Reproduction: asexual except for bacterial conjugation

Motility: motile if flagella/pili are present

Environment/Habitat: extremophiles love extreme environments

Example: archaebacteria in Yellowstone hotsprings

Animalia

Domain: Eukarya

Number of Cells: multicellular eukaryotes

Presence/Composition of Cell Wall: none

Mode of Nutrition: heterotrophic

Reproduction: sexual reproduction (sometimes asexual)

Motility: motile

Environment/Habitat: aquatic + terrestrial environments

Example: dog

Plantae

Domain: Eukarya

Number of Cells: multicellular eukaryotes

Presence/Composition of Cell Wall: cell walls of cellulose

Mode of Nutrition: photosynthetic

Reproduction: sexual reproduction (includes self-reproduction) and some asexual

Motility: not motile

Environment/Habitat: aquatic + terrestrial environments

Example: tree

Fungi

Domain: Eukarya

Number of Cells: mostly multicellular eukaryotes

Presence/Composition of Cell Wall: cell walls of chitin

Mode of Nutrition: heterotrophic

Reproduction: sexual reproduction (sometimes asexual)

Motility: not motile

Environment/Habitat: mostly terrestrial environments

Example: mushroom

Protista

Does not fit into other 3 Kingdoms - like a miscellaneous group

Domain: Eukarya

Number of Cells: mostly unicellular

Presence/Composition of Cell Wall: some have cell walls

Mode of Nutrition: some heterotrophic, some autotrophic

Reproduction: sexual and asexual reproduction

Motility: some motile

Environment/Habitat: mostly aquatic environments

Taxon Order

D, K, P, C, O, F, G, S

Cladogram

Shows relationship between species through branching diagram

Clade

Group of species with single common ancestor & common traits

Root

Common ancestor of the whole cladogram

Node

Common ancestor shared by branching lineages, represents speciation event

Terminal Branch

extant species at the end of a branch

Derived characteristic

Used to assort organisms into clades - a trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants.

Outgroup

A very unrelated group on a cladogram to act as a point of comparison

Figworts

Figwort family extensively expanded after reclassification, adding 3 new families to encompass all the species.

Evolution

A fact and a theory - the change in heritable characteristics (gene frequencies) of a population over time

Gene Flow

Mechanism of Evolution - emigration/migration of species moving in and out altering gene pool within a population

Genetic Drift

Mechanism of Evolution - change in gene pool due to random chance - NOT A SELECTIVE PRESSURE b/c entirely random

Bottleneck effect: sudden decrease in population = less adaptive in future

Founder effect = new breakaway population doesn’t fully represent former population

Molecular data/phylogeny

Evidence for Evolution - All living things use DNA, allowing for cross-species comparisons that define relationships based on differences in nucleotide sequences and proteins - MOST RELIABLE

Molecular clock

measures time since recent common ancestor with changes in DNA - ex. species with more similarities diverged more recently

Selective breeding/artificial selection

Evidence for Evolution - Mirrors natural selection with artificial pressures of human selection altering plant and animal traits.

Homologous structures

Evidence for Evolution - Traits shared with closely related species that have a similar structure but different functions, exemplifying divergent evolution

ex. Pentadactyl limbs: a five-digit limb that tetrapods share but for different uses. Some use for flying, grasping, swimming, etc.

Analogous structures

Evidence for Evolution - Traits that have similar functions but not structure, does NOT suggest relation, exemplifying convergent evolution

ex. Bird wings + Dragon fly wings: same function to fly but very different structures

Vestigial structures

Evidence for Evolution - Traits that lost their original function but remain in organisms as they are still part of DNA - as long as they are not costly to make

ex. Wisdom Teeth: no longer needed but many people still have them

Embryology

Evidence for Evolution - study of the development of embryos, revealing cross-species similarities. Similar embryos with different adult forms suggest common ancestor

Biogeography

Evidence for Evolution - includes convergent and divergent evolution and adaptive radiation

Convergent evolution

Independent development towards similar traits due to common environmental pressures - does NOT SUGGEST RELATIONSHIP

Divergent evolution

Development from a recent common ancestor into more specialized traits w/o same function - DOES SUGGEST RELATIONSHIP

Adaptive radiation

Evidence for Evolution - Organisms generationally diversify from ancestral form with changes in the environment that open new limitations and ecological niches = biodiversity

Ecological niches

Match of a species to a specific environmental condition, describing how a species reacts to environmental disruptions and their role.

Fossil record

Evidence for Evolution - incomplete, but helpful to discovering traits of extinct/ancestral species with radiometric dating and transitional fossils

Law of superposition

Oldest fossils are found at the bottom and newest are at the top

Radiometric dating

Tool used to deduce age of rocks and fossils from measuring the decay of elements like carbon, signifying its age

Transitional fossil

Shows intermediate traits between ancestral forms and descendants

Allopatric speciation

Speciation that occurs in different locations due to geographic isolation

Sympatric speciation

Speciation that occurs in the same location due to same-area reproductive isolation (temporal, behavioral, ecological, etc.)

Prezygotic barrier

an obstacle in mating/fertilization - prevents hybridization

Geographic isolation

Prezygotic barrier + Allopatric speciation - populations are reproductively isolated due to physical barriers

Temporal isolation

Prezygotic barrier + Sympatric speciation - populations are reproductively isolated due to different timing in reproductive cycle

Behavioral isolation

Prezygotic barrier + Sympatric speciation - populations are reproductively isolated due to different mating behaviors

Ecological isolation

Prezygotic barrier + Sympatric speciation - populations are reproductively isolated by never meeting as they are used to different habitats

Mechanical isolation

Prezygotic barrier + Sympatric speciation - populations are reproductively isolated due to physical differences preventing reproduction from occuring

Postzygotic barrier

reduced viability of zygote, adolescent, and adult. decreased fertility of hybrid and offspring - prevents hybridization

Reduced Hybrid Viability

Postzygotic barrier - hybrid less viable to survive and reach sexual maturity

Reduced Hybrid Fertility

Postzygotic barrier - hybrid is viable but sterile and can therefore not produce offspring

Gradualism

Steady and gradual transformation into new species (cumulative)

Punctured equilibrium

Abrupt and rapid change into new species

Polyploidy

heritable condition of posessing more than two sets of chromosomes (anything more than diploid)

Autopolyploidy

Hybrid with multiple chromosome sets from the same parent species. Arises from issues during mitosis (like a doubling of chromosomes without cell division) = tetraploid

Allopolyploidy

Hybrid with multiple chromosome sets from different parent species - NOT from self-fertilization

Speciation occurs if resulting offspring from allopolyploidy can only produce with its own new species

Knotweeds

example of allopolyploidy - have produced many allopolyploid offspring

Lamarck

Created the theory of Acquired Traits as first proposed theory of evolution based off of use and disuse of characteristics - WRONG

Theory of Acquired Traits

Organisms can pass on acquired traits based on use and disuse - WRONG

Charles Darwin

Created theory of Natural Selection - CORRECT - and published paper “Origin of the Species.” Also known for his studies on the Galapagos finches

Galapagos Islands

Darwin observed ground finch species on different Galapagos Islands having tailored beaks to the differing food sources. He concluded that the finches came from one mainland species that migrated to outer islands where adaptive radiation took place = change in environment = new challenges = new development

Natural Selection

Mechanism of Evolution - Variations are inherited (NOT acquired traits) and successful variations are more likely to survive, reproduce, and pass more genetic material onward - CORRECT

Genetic Mutation

Mechanism of Evolution - random alteration in the nucleotide sequence of a gene - basis of natural selection and can even cause evolution itself. ONLY MUTANTS IN GAMETE-PRODUCING CELLS ARE INHERITED

Competition

Concept of Natural Selection -Overproduction means organisms will compete for limited resources and only the fittest can survive

Fitness

Concept of Natural Selection - A measure of reproductive success (you must survive to reproduce) as some variations allow some organisms to better survive than others (DEPENDENT ON ENVIRONMENT)

Survival of the fittest

Only the organisms with the most successful variations can survive and reproduce