Micro- and Macroevolution Flashcards
Robert Hooke (1665)
saw “small rooms” in a microscope in cork: cellula
cells
▪ smallest living biological structures
▪ basic unit of life
▪ types: prokaryotes and eukaryotes
prokaryotes
▪ single celled
▪ ex. bacteria, blue green algae
▪ originated 3.7 billion –4+ billion years ago
eukaryotes
▪ multi-celled
▪ ex. plants, birds, mammals, reptiles, etc.
▪ originated 1.2 billion years ago; more complex forms 600 –800 million years ago
Sir. David Attenborough
▪ last remaining naturalist
▪ goals is to protect the planet
cells in humans
▪ adult: 1 trillion cells
▪ together it functions to allow organism to survive
▪ structural similarities despite outward appearances
eukaryotic cells
▪ 3D structure contains: carbohydrates, lipids (fats), nucleic acid, proteins
organelles
organ systems/little organs
nucleus
control centre of cell; contains DNA and RNA
▪ genetic material important for cell function and survival
mitochondria
power plant of cell; contains mtDNA; inherited from mother
▪ numerous
▪ paleoanthropologist use it to evaluate degree to which organisms and fossils are related to each other
▪ determines shared evolutionary relationships
ribosomes
create protein within cell
somatic cells
▪ tissue cells (ex. hair, skin, muscle, cilia, etc.)
▪ form body of an organism
▪ nonreproductive cells
gametes
▪ sperm + egg = zygote
▪ transmit genetic info
▪ sex cells
DNA: The Universal Code
▪ deoxyribonucleic acid
▪ contains genetic material that directs function and development
▪ organisms differ in arrangement and regulation of their DNA
▪ main function is to direct protein production (protein synthesis)
▪ 4 chemical bases (A, G, T, C): organization dictates function and development (99% identical to all people)
base pairs
▪ DNA bases joining together
▪ only bond with specific bases (thymine + adenine, guanine + cytosine)
nucleotide chain
base + sugar + phosphate
double helix
spiral of nucleotide chains
DNA replication
▪ growth, development and repair requires cells to replicate
▪ enzymes sever bonds between base pairs → bases attract unattached DNA nucleotides within cell nucleus
▪ result is two double-stranded DNA molecules identical and consist of one new and old strand of DNA
proteins
▪ main function of DNA is to produce protein (protein synthesis)
▪ give structure (ex. collagen)
▪ bind to molecules (ex. hemoglobin)
▪ enzymes (ex. lactase)
▪ hormones (ex. insulin)
▪ regulatory proteins: bind to DNA, can switch genes on/off
time: 27mins
amino acids
building blocks of protein
▪ 20 kinds that allow proteins to differ from one another in number and sequence
▪ DNA specifies amino acid type via order of chemical bases (A, T, C and G) into groups
protein synthesis/formation of new proteins
▪ production of protein occurs in ribosomes
▪ ribosomes organize amino acids to form different kinds of proteins
▪ DNA copied into messenger RNA (mRNA) → travels from nucleus to ribosomes
▪ transcription: formation of mRNA
▪ ribosomes use information in mRNA to create new proteins (translation)
genes
▪ units of heredity
▪ sequences of DNA bases that specify or identify the order of amino acids for a protein, part of a protein or another functional product
▪ contain info to build and maintain cells
▪ all organisms have genes that correspond to their diff bio traits (hair, eyes, tolerance to certain illnesses, blood type)
▪ control expression, inheritance, evolution of bio traits
genome
genetic makeup of an organism
mutation
change in sequence of chemical bases
▪ source of new variation in pop
▪ needs to be inherited by the offspring and common
chromosomes
▪ strands of DNA found within nucleus
▪ carry info on cell function and heredity
▪ number depends on species (humans have 46 chromosomes, arranged in 23 pairs)
▪ humans have 22 pairs of autosomes + 1 pair sex chromosomes –inherit one of each pair from each parent
autosomes
carry genetic info for physical characteristics
sex chromosomes
▪ biologically female mammals: XX
▪ biologically male mammals: XY
▪ role of sex hormones
▪ genes create sex hormones that influence on the expression of our bio sex (variation and diversity)
locus
place/position of gene on chromosome
▪ might be one alt form of a gene
allele
alt form of gene
▪ affect the same trait (ex. eye colour)
cell division
division of a cell into two daughter cells with the same genetic material
mitosis
▪ occurs during growth, aging, injury in somatic cells
▪ produces new cells
meiosis
▪ creates sex cells
▪ results in 4 daughter cells each with 23 chromones
Gregor Mendel (1822 –1884)
▪ Charles Darwin and blended inheritance
▪ Mendel’s experiments on pea plants
▪ offspring are not blended
▪ offspring follow predictable pattern in expression of traits (“factors”/genes); one inherited from each parent
▪ dominant and recessive alleles
▪ experiments successfully showed how heredity occurs in very simple/discrete/mendelian traits
phenotype
physical expression of the genes controlling for ex. pod colour
genotype
genetic makeup of individuals
discrete traits
controlled by alleles at single locus
ex. albinism, left chin, hypodontia of lateral incisors, ABO blood group system
table 3.2 in textbook
dominant trait conditions
occurs if one of the allele is inherited
ex. achondroplasia (dwarfism), Marfan syndrome, Huntington disease
recessive trait conditions
individual has to inherit it by both parents (if they inherent one of the alleles then they will be a carrier)
ex. cystic fibrosis, Tay-Sachs disease, Sickle-cell anemia
time: 1:05:45
Mendelian traits summary
Mendelian traits
▪ influenced by a single genetic locus
▪ traits discrete, less complex
▪ less environmental influence on gene expression
▪ few phenotypes possible (because of discrete traits)
ex. Marfan syndrome
Polygenic traits/Non-Mendelian traits
▪ influenced by +2 genetic loci
▪ continuous traits, more complex
▪ environmental influence on gene expression possible
▪ many phenotypes possible (because of continuous traits)
ex. skin colour
natural selection
organisms that are better adapted to their environment are more likely to survive and contribute genetic material to subsequent generations
artificial selection
humans selectively breed for desirable traits; some are beneficial, others are not
▪ pros: increase change in pop
▪ cons: breeding problems and can’t survive on their own
sexual selection
selection for features/behaviors associated with mating
ex. male peacock tail attracts females
mutation
▪ change in order of chemical bases
▪ can also occur in response to environmental conditions or replication error
▪ source of new variation in a pop
▪ must occur in a gamete to be evolutionarily significant
▪ can pos or neg affect organism
▪ only way to produce new genes
gene flow
▪ transmission, sharing or exchange of genes between pops though interbreeding
▪ important way variation is redistributed among pops
▪ individuals mate in new population, but don’t necessarily stay there
genetic drift
▪ random, occurs in small pops
▪ alleles become more/less prevalent (ex. Founder Effect)
Founder Effect
▪ occurs when a small group separates from a diverse population
▪ restricted representation of alleles in founding group due to genetic bottleneck
▪ if breeding is restricted, subsequent generations have low genetic variability–susceptible to extinction
▪ rare alleles can become more common
▪ occurs after colonization of new areas (ex. porphyria)
genetic bottleneck
reduction in diversity in a founding pop
▪ greatly reduced genetic diversity is bad for the pop bc if the environment changes, they don’t have enough diversity to deal with that change (could lead to mass extinction)
evolution from a bio perspective
change in allele frequency from one generation to the next
▪ two-step process:
- production and distribution of variation
- natural selection acting on this variation
microevolution
change at the microscopic level
macroevolution
results in formation of new species
classification
a means to organize biodiversity
Linnaean Classification of Humans
Kingdom: Animalia (animals) Phylum: Chordata (chordates) Class: Mammalia (mammals) Order: Primates (primates) Family: Hominidae (hominids) Genus: Homo (humans) Species: Homo sapiens
taxonomic conventions (rules)
▪ first letter of genus capitalized (Homo)
▪ species begins with lowercase letter (Homo sapiens)
▪ genus and species are both italicized (Homo sapiens)
▪ genus name may be abbreviated (H. sapiens)
Kingdom: Animalia
▪ eukaryotic ▪ motile (can move) ▪ heterotrophic (dependent on other organisms as a food source) ▪ Precambrian period (~610Ma)
Phylum: Chordata
▪ notochord: precursor to the spine, rod-like ▪ nerve cord ▪ gill slits ▪ muscles ▪ Cambrian (~540Ma)
Subphylum Vertebrata
▪ segmented bony spinal column ▪ jawless and bony fishes, sharks, rays, amphibians, reptiles, mammals, birds ▪ segmental spinal column ▪ developed brain, paired sensory structures (balance, sight, olfaction: sense of smell) ▪ heads and tails ▪ closed circulatory system ▪ upper Cambrian (~510Ma)
Class: Mammalia
▪ sweat glands (including mammary glands/production of milk)
▪ hair
▪ auditory ossicles: transmit sound vibrations to inner ear
▪ neocortex: sensory perception, motor function, spatial reasoning, conscious thought and language
▪ longer ontogeny (period of growth and development)
▪ viviparous (live young)
▪ specialized dentition/heterodont
▪ endothermic (regulated body temp)
▪ Jurassic (~199-145Ma)
Order: Primates
▪ lemurs, lorises, tarsiers, monkeys, apes, humans
▪ generalized structure (ex. pentadactyly: 5 digits/hands and fingers, ↑ gestation/ontogeny, dentition, limb structure)
▪ binocular stereoscopic vision
▪ opposable thumbs, grasping hands/feet, nails
▪ ~65 Ma
binocular stereoscopic vision
overlapping fields of view with 3D depth perception
Homology (Richard Owen, 1848)
▪ similarities between organisms due to descent from a common ancestor
▪ archetype: all vertebrates must have a common structural plan
ex. tetrapod forelimb bone number and form
Homologous characters
▪ observable part/attribute of an organism
▪ Primitive/ancestral: inherited from an ancient ancestor
▪ derived: changed from the ancestral condition (more recent and useful in identifying descendent lineage)
analogy
similarity due to common function rather than descent from a common ancestor
ex. bird and incest wings
homoplasy
process that leads to analogy; separate evolutionary development of similar characteristics in different groups of organisms
Evolutionary/Phylogenetic Systematics
▪ patterns of ancestor-descendant relationships using analysis of homologous characters
▪ Phylogenetic tree
▪ Time
▪ Divergences
Phylogenetic tree
depicts order of splitting events when new species are formed
Cladistics
▪ determines patterns of relatedness using shared derived characters
▪ Cladogram: Monophyletic groups
▪ shows living and fossil organisms together
Monophyletic groups
members are more closely related to each other than to any species outside the group
Similarities of Evolutionary Systematics and Cladistics
▪ branching diagrams
▪ patterns of relatedness; constructing classifications to reflect close evolutionary relationships
▪ character analysis (visible traits)
▪ homologous characters (shared from recent common ancestor)
Differences of Evolutionary Systematics and Cladistics
▪ time (Evolutionary systematics)
▪ ancestor-descendant relationships (Evolutionary systematics) vs fossil and living species analyzed together (Cladistics)
Biological Species Concept
species is a group of interbreeding or potentially interbreeding organisms that produce fertile offspring and that are reproductively isolated from all other such groups (not defined similar to appearance)
Problems with BSC
▪ Demonstrating capacity to successfully interbreed
▪ Asexually reproducing species?
▪ Hybrids?
▪ The fossil record
fossil
physical or trace remains of an organism that once lived
ex. bones, teeth
Paleospecies
▪ species defined from the fossil record
▪ comparison of past and living species
▪ time (!)
▪ + variation in extinct species
Sources of Variation
▪ ontogenetic
▪ sexual
▪ inter- and intraspecific
▪ temporal
ontogenetic
differences in size/shape due to age; children poorly represented in the fossil record
sexual
sexual dimorphism: differences in size/form between males and females of a single species
ex, proboscis male monkeys have big noses and females have small noses
inter- and intraspecific
within and between species
temporal
▪ variation due to time (fossils)
▪ chronospecies: different parts of the same evolving lineage
ex. homo erectus had a long temporal range and lasted over 1 million years (million years ago will look a bit more primitive than homo erectus 1000 years ago)
