Classification, Evolution, Speciation, and Cladistics Test Flashcards
Outline the different characteristics of the 3 domains of life.
DOMAIN
- Prokaryotic or Eukaryotic?
- Single or multicellular?
- Naked DNA?
- Cells walls (and made of)?
- Other characteristics/ Examples
ARCHAEA
- Prokaryotic
- Single-celled
- DNA associated with proteins
- Cell walls NOT made of peptidoglycan
- Live in extreme environments (thermophiles etc.)
EUBACTERIA
- Prokaryotic
- Single-celled
- Naked DNA
- Cell walls made of peptidoglycan
- Bacteria
EUKARYA
- Eukaryotic
- Single OR multicellular
- DNA associated with HISTONE proteins
- Animals do not have cell walls (all others do)
- Have membrane-bound organelles; Fungi, Plants, Animals, and Protists
Identify organisms most closely related based on their scientific names and classification.
Scientific naming (Latin or Greek names) – BINOMIAL NOMENCLATURE (universal among biologists and has been agreed upon and developed at a series of congresses)
- Use the Genus (capitalized) name followed by the species name (lowercase)
- If genus is the same, they’re closely related; if species is the same, they’re the same species (duh) and thus more closely related; subspecies may be a third word in the scientific name
Know the order of the taxa (in increasing and decreasing size)
Taxa: (biggest to smallest)
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Outline the different characteristics of the 4 plant phyla (and be able to identify plants as belonging to each phylum - you’ll need to be able to spell the names too).
LOOK AT NOTES - Classification and Figwort Reclassification slide 8: https://docs.google.com/presentation/d/1bEm1taD33OlTGeTibRIn5zpvOUBXipZso2zQj1CtPQ0/edit#slide=id.g1f5a50025d2_0_573
Phylum Bryophyta: Non-vascular Plants
- small; lacking leaves/ stems; no xylem/ phloem tissue; reproduce using spores – ex: mosses & liverworts
Phylum Filicophyta
- have pinnate leaves (leaflets on stalks); reproduce using spores released from sori – ex: ferns
Phylum Angiospermophyta
- (“angiosperms”)
- flowering plants
Phylum Gymnospermophyta/ Coniferophyta
- (“gymnosperms”)
- seeds are in cones (naked seeds)
Outline the different characteristics of the 6 phyla of invertebrate animals (and be able to identify invertebrates belonging to each phylum).
Porifera
- Symmetry: Asymmetrical
- Body Cavity: None (have pores)
- Segmentation: None
- Other Features: Spicules for support
- Examples: Sea sponge
Cnidaria
- Symmetry: Radial
- Body Cavity: Mouth but no anus
- Segmentation: None
- Other Features: Stinging cells (cnidocytes)
- Examples: Jellyfish, coral, sea anemone
Platyhelmintha
- Symmetry: Bilateral
- Body Cavity: Mouth but no anus
- Segmentation: None
- Other Features: Flattened body (increased SA: Vol ratio)
- Examples: Tapeworm, planaria
Annelida
- Symmetry: Bilateral
- Body Cavity: Mouth and anus
- Segmentation: Segmented
- Other Features: Move via peristalsis
- Examples: Earthworm, leech
Mollusca
- Symmetry: Bilateral
- Body Cavity: Mouth and anus
- Segmentation: Non-visible (mantle & foot)
- Other Features: May have a shell (made by mantle)
- Examples: Snail, octopus, squid, bivalves
Arthropoda
- Symmetry: Bilateral
- Body Cavity: Mouth and anus
- Segmentation: Segmented
- Other Features: Exoskeleton (chitin)
- Examples: Insects, spiders, crustaceans
Outline the different characteristics of the 5 classes of vertebrate animals (and be able to identify vertebrates belonging to each class).
Vertebrata: sub-phylum of Chordata
Fish
- Body covering: Scales made out of bony plates
- Reproduction: External
- Breathing: Gills
- Temperature: Ectothermic
- Other Features: Have a swim bladder
Amphibian
- Body covering: Moist skin
- Reproduction: External
- Breathing: Simple lungs (and via skin)
- Temperature: Ectothermic
- Other Features: Larval state in water, adult state on land
Reptile
- Body covering: Scales made out of keratin
- Reproduction: Internal (lays soft eggs)
- Breathing: Lungs with extensive folding
- Temperature: Ectothermic
- Other Features: Simple teeth with no living tissue
Bird
- Body covering: Feathers
- Reproduction: Internal (lays hard eggs)
- Breathing: Lungs with bronchial tubes
- Temperature: Endothermic
- Other Features: Have wings and beaks with no teeth
Mammal
- Body covering: Hair
- Reproduction: Internal - live births (except monotremes)
- Breathing: Lungs with alveoli
- Temperature: Endothermic
- Other Features: Feed young with milk from mammary gland
Be able to use a dichotomous key (and to construct one as well).
LOOK AT NOTES - Classification and Figwort Reclassification slide 12: https://docs.google.com/presentation/d/1bEm1taD33OlTGeTibRIn5zpvOUBXipZso2zQj1CtPQ0/edit#slide=id.g1f5a50025d2_0_926
LOOK AT DICHOTOMOUS KEY ACTIVITY
- Dichotomous keys are tools based on a series of binary (two-part) questions or categories that allow us to identify organisms.
- Dichotomous keys are based on features that stay the same (such as physical structures or biological processes) and they are represented as a series of paired statements laid out in a numbered sequence (descriptive) or as branching flowcharts (diagrammatic)
Define evolution and explain how evolution happens (natural selection).
- Evolution is the process of cumulative change (in the heritable characteristics of a population) over time
- Evolution happens by means of natural selection: environmental pressures (an unstable environment) allow only SOME members of a population to survive and reproduce (those best adapted to the environment survive) and pass on their genes – over time, more and more of the population possess these genes/ alleles for these characteristics (note that evolution and natural selection tend to decrease variation in populations)
- Natural selection acts on HERITABLE characteristics ONLY (NOT on acquired characteristics, as they are not based on genes and cannot be passed on from parent to offspring)
- Genetic variation comes from crossing over in prophase I, random (independent) assortment in metaphase I, and sexual reproduction and random fertilization
Outline the evidence for evolution provided by fossils, selective breeding/ artificial selection, and homologous structures (the pentadactyl limb).
Understand that the Fossil Record (the totality of
fossils) provides evidence for evolution
- Paleontologists have been collecting/ classifying fossils for nearly 200 years. Fossil evidence is either direct (remains of organisms) or indirect (trace fossils – footprints, tracks, tooth marks etc.)
- Overall, fossils show us:
- The characteristics of living things have changed from ancestral forms over LONG periods of time (evolutionary change)
- Examples: Vestigial organs and homologous structures
- The sequence of life that fossils show us matches the expected sequence of evolution (prokaryotes before eukaryotes, ferns before flowering plants, reptiles before mammals, and amphibians before reptiles etc.)
- Around the world, different kinds of organisms are found in rocks of particular ages in a consistent order (law of fossil succession) – older fossils are (typically) deeper
- Over 99% of all life that has EVER existed on Earth is extinct!
- Age can be determined using radioisotopes, and fossils can yield DNA samples for molecular dating/ analysis
Understand that selective breeding of domesticated animals shows that artificial selection can cause evolution
- For many years, humans have been selectively choosing which domesticated animals and plants to breed (to produce desired traits in their offspring)
- Cattle (meat/ milk), Horses (speed/ strength/ endurance), Dogs (hunting, herding, racing), Crops (drought resistance) etc.
- Domesticated animals and plants which have been selectively bred for many generations can show rapid/ significant variation compared to their wild counterparts – this is artificial selection as the driving force is human choice, NOT the environment! SHOWS that selection can cause species to change over time!
Understand that evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
- Certain anatomical structures in different organisms are similar, implying common ancestry (common evolutionary origins)
- Homologous structures are similar in structure (built with same basic parts), but are are used for different functions or in different ways (often found in dissimilar species too - “variations on a theme”)
- Homologous structures develop by adaptive radiation: several species “rapidly” diversify from a common ancestor to fill/ use new niches (roles/ positions in communities) - Ex: Galapagos finches (variations in beaks for diff. foods)
Application: Comparison of the Penta (‘five’) dactyl (‘finger’) limb of mammals, birds, amphibians, and reptiles with different modes of locomotion
- Similar bone structure in forelimbs that are used by different organisms for different modes of locomotion (bat/ bird wings for flying, whale front fins for swimming, human hands for tool manipulation, horse forelimbs for galloping etc.) demonstrates that a similar basic plan has been adapted to suit various environments
- Note: the humerus, radius, ulna and carpals are found in ALL of these organisms (cat, human, horse, whale, dolphin, frog, bat, lizard, penguin, pterodactyl, mole, pig, anteater etc.)
Compare analogous (convergent evolution) and homologous structures (divergent evolution/ adaptive radiation).
Homologous Structures:
- Similar (in structure) because they are derived from a common ancestor (often used for different functions by related organisms)
- Example: Pentadactyl limbs in mammals, birds, reptiles, and amphibians (same structures due to common ancestor, but usually used for different functions to fill different niches/ environments - DIVERGENT EVOLUTION)
Analogous Structures:
- Similar because they serve a common function, but they are different in structure because they are derived from different evolutionary paths (arise due to the need to perform the same function in an environment - exposure to same selective pressures in the environment causes development of similar features to perform similar functions but come from different lineages/ different ancestors - CONVERGENT EVOLUTION)
- Example: Wings of birds and insects; Fins of fish and turtles (evolved to serve same functions in same environment, but different structures due to different ancestors)
- Note that classification of organisms based on analogous structures causes dissimilar species to be classified together (original mode of classification). Natural classification today is based on homologous structures (based on common ancestry/ genetics/ evolutionary history).
Outline the sources of variation within a population.
LOOK AT NOTES - Evolution and Natural Selection slide 3: https://docs.google.com/presentation/d/1YUUDWkVFj3SnedbwlaEn-24yvoptJKYNn3TWgpCN3L8/edit#slide=id.p13
Variation is a result of random mutation (DNA replication, viral infection) and sexual reproduction.
Variation occurs within sexual reproduction as a result of random fertilization and meiosis (crossing over in prophase I and random assortment in metaphase I)
Genetic Variation: Due to meiosis, there is almost infinite genetic variation in gametes (reproductive cells – sperm and ova)
- Crossing over in prophase I – creates new combinations of alleles on a chromosome (recombination)
- Random (independent) assortment in metaphase I – chromosomes line up and separate randomly, producing 2n possible combinations of chromosomes in gametes (n = haploid number of chromosomes, 2n in humans = 223 = 8,388,608 possible combinations of chromosomes in gametes – in ONE INDIVIDUAL!)
- Sexual reproduction and random fertilization – any one of the gametes from one individual can fertilize any one of the gametes from the other individual
- Note: This doesn’t even take into account random gene and chromosomal mutations! (remember that not all mutations are favorable though – if not favorable, will not survive and be passed on)
Outline the reclassification of the figwort family.
LOOK AT NOTES - Classification and Figwort Reclassification slide 16: https://docs.google.com/presentation/d/1bEm1taD33OlTGeTibRIn5zpvOUBXipZso2zQj1CtPQ0/edit#slide=id.g184dc38b89_0_81
- The Figwort Family (Scrophulariaceae) used to be a happy, large family of angiospermatophyta that included snapdragons, figworts, monkeyflowers, foxglove, and many other attractive garden and wildflowers.
- Biologists had classified the Scrophulariaceae plants using external morphology features.
NEW EVIDENCE:
- Olmstead et al (2001) compared three chloroplast DNA genes (totalling 4200 bases) across 65 plant species. The results were analysed by a computer program to try to give the simplest explanation of the differences found. This extract of the cladogram is adapted from the data.
RESULT:
- It was found that the species who were all originally in the Scrophulariaceae were not closely related to each other.
- As a result of the DNA evidence, the Scrophulariaceae family has suffered a nasty divorce. The old Scrophulariaceae has now been split into at least six smaller clades (Olmstead, et. al 2001).
- DNA evidence identifies that similarities between members of the old Scrophulariaceae family were analogous.
- The flower shape evolved independently from different ancestors (convergent evolution) because they shared similar selective pressures (pollinators and seed dispersal strategies).
RECLASSIFICATION:
- As new evidence is discovered (in this case, DNA sequences), older ideas for classification need to be reassessed and sometimes changed.
- Sometimes new evidence shows that members of a group do not share a common ancestor, so the groups are split and moved into different clades
- Sometimes members of different groups are found to be closely related, so the groups are merged into a single clade
Outline the characteristics that define members of a species.
Species:
- Can interbreed
- Produce fertile offspring
- Have same chromosome number/ chromosome type
- Same sequences of genes on chromosomes
- Similar traits/ phenotypes
Define speciation, and distinguish between allopatric and sympatric speciation (and know which modes of reproductive isolation (geographic, temporal, and behavioral) result in each type).
Speciation: formation of new species (no longer able to interbreed)
Allopatric:
- Two populations evolve separately (diverge) and may eventually no longer be able to interbreed due to geographic isolation = physical barriers (i.e. land, water) prevent males and females from interbreeding (ex: river, mountain, volcano separating populations in same location) - can be caused by migration too
Sympatric:
- Divergence of species without a physical barrier; Same geographical location, but reproductively isolated either temporally or behaviorally.
- Temporal isolation = Timing differences in reproductive cycles/periods/activities. (Ex: female parts of flower population reaching maturity at different time compared to pollen release in another population, mammal hibernation/migration)
- Behavioral isolation = Incompatible courtship patterns. (Ex: varying mating songs in insects, birds feather ruffling)
Describe stabilizing selection, directional selection, and disruptive selection (and be able to identify examples of each type).
Stabilizing Selection:
- ONE (“middle of the road”)
intermediate phenotype is favored over TWO extreme phenotypes (ex: flowering plant nectar, human birth weights). Occurs when environmental conditions are stable & competition is low. *Result of a variation in environment; food/space/etc
Directional Selection:
- ONE phenotype is favored over another by natural selection. Over time, the favored phenotype will increase whereas the other will decrease. *Typically due to a gradual change in the environment (ex: peppered moth, Galapagos finches) = Adaptive radiation
Disruptive Selection:
- TWO extreme phenotypes are favored over the intermediates. *Results from fluctuating environment conditions (seasons); food/space/etc.
