Classification, Evolution, Speciation, and Cladistics Test Flashcards
Determining Domain
-Prokaryotic or Eukaryotic?
-Single or multicellular?
-Naked DNA?
-Cells walls (and made of)?
Domain of Life: ARCHAEA
-Prokaryotic
-Single-celled
-DNA associated with proteins
-Cell walls NOT made of peptidoglycan
-Live in extreme environments (thermophiles etc.)
Domain of Life: EUBACTERIA
-Prokaryotic
-Single-celled
-Naked DNA
-Cell walls made of peptidoglycan
-Bacteria
Domain of Life: 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
Binomial Nomenclature
-Scientific naming (Latin or Greek names)
-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
Order of Taxa (Biggest to Smallest)
Kingdom
Phylum
Class
Order
Family
Genus
Species
Phylum Bryophyta (Plant)
-Non-vascular Plants (no xylem/ phloem tissue)
-small
-lacking leaves/ stems
-reproduce using spores
–ex: mosses & liverworts
Phylum Filicophyta (Plant)
-have pinnate leaves (leaflets on stalks)
-reproduce using spores released from sori
–ex: ferns
Phylum Angiospermophyta (Plant)
-(“angiosperms”)
-flowering plants
Phylum Gymnospermophyta/ Coniferophyta (Plant)
-(“gymnosperms”)
-seeds are in cones (naked seeds)
Invertebrate Phyla: Porifera
-Symmetry: Asymmetrical
-Body Cavity: None (have pores)
-Segmentation: None
-Other Features: Spicules for support
-Examples: Sea sponge
Invertebrate Phyla: Cnidaria
-Symmetry: Radial
-Body Cavity: Mouth but no anus
-Segmentation: None
-Other Features: Stinging cells (cnidocytes)
-Examples: Jellyfish, coral, sea anemone
Invertebrate Phyla: Platyhelmintha
-Symmetry: Bilateral
-Body Cavity: Mouth but no anus
-Segmentation: None
-Other Features: Flattened body (increased SA: Vol ratio)
-Examples: Tapeworm, planaria
Invertebrate Phyla: Annelida
-Symmetry: Bilateral
-Body Cavity: Mouth and anus
-Segmentation: Segmented
-Other Features: Move via peristalsis
-Examples: Earthworm, leech
Invertebrate Phyla: 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
Invertebrate Phyla: Arthropoda
-Symmetry: Bilateral
-Body Cavity: Mouth and anus
-Segmentation: Segmented
-Other Features: Exoskeleton (chitin)
-Examples: Insects, spiders, crustaceans
Vertebrate Class: Fish
-Body covering: Scales made out of bony plates
-Reproduction: External
-Breathing: Gills
-Temperature: Ectothermic
-Other Features: Have a swim bladder
Vertebrata
sub-phylum of Chordata
Vertebrate Class: 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
Vertebrate Class: 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
Vertebrate Class: 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
Vertebrate Class: 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
Dichotomous Keys
-Tools based on a series of binary (two-part) questions or categories that allow us to identify organisms.
-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)
Evolution Definition
The process of cumulative change (in the heritable characteristics of a population) over time
How does Evolution occur? (Natural Selection)
-Environmental pressures allow only SOME members of a population to survive and reproduce (those best adapted to the environment survive) and pass on their genes
–More of population possess these genes/ alleles overtime (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
The Fossil Record (the totality of
fossils) provides evidence for evolution
-Paleontologists have been classifying fossils for nearly 200 years.
-Fossil evidence is either direct (remains of organisms) or indirect (trace fossils – footprints, tracks, tooth marks etc.)
-Fossils show 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
Selective breeding of domesticated animals shows that artificial selection can cause evolution
-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!
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.)
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)
-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).
Variation Overview
-A result of random mutation (DNA replication, viral infection) and sexual reproduction.
-Occurs within sexual reproduction as a result of random fertilization and meiosis (crossing over in prophase I and random assortment in metaphase I)
Sources of Genetic Variation
-Due to meiosis, there is almost infinite genetic variation in gametes (reproductive cells – sperm and ova)
1. Crossing over in prophase I – creates new combinations of alleles on a chromosome (recombination)
2. 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!)
3. 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 account for random gene and chromosomal mutations! (not all mutations are favorable though – if not favorable, will not survive and be passed on)
Figwort Family Overview
-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.
Figwort 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.
Figwort Result
-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.
-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, older ideas for classification need to be 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
What defines members of a species?
-Can interbreed
-Produce fertile offspring
-Have same chromosome number/ chromosome type
-Same sequences of genes on chromosomes
-Similar traits/ phenotypes
Speciation Definition
formation of new species (no longer able to interbreed)
Allopatric Speciation (Geographic Isolation)
-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 also be caused by migration
Sympatric Speciation
Divergence of species without a physical barrier; Same geographical location, but reproductively isolated either temporally or behaviorally. (Can include temporal and behavior isolation)
Temporal Isolation (Sympatric Speciation)
Timing differences in reproductive cycles. (Ex: female parts of flower population reaching maturity at different time compared to pollen release in another population, mammal hibernation/migration)
Behavioral Isolation (Sympatric Speciation)
Incompatible courtship patterns. (Ex: varying mating songs in insects, birds feather ruffling)
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.
Clade
a group of organisms that have evolved from a common ancestor (natural classification)
What is used in cladogram construction?
-Morphological homologies: presence, size, and shape of body parts
-Development patterns (embryology)
-Fossil records - when & where organisms lived in the past and what they looked like
-Genetically determined behavioral traits
-Molecular homologies
DNA sequence homologies:
-Nuclear DNA
-Mitochondrial DNA
-Chloroplast DNA
-Amino acid sequence homology of proteins
*Note that the base sequences of a gene are used over the corresponding amino acid sequences of a protein (when possible) as there are multiple DNA (mRNA) triplets that can code for one amino acid
Describe how DNA base sequences can be used as a “molecular clock” to determine the timing of divergence between related organisms (and discuss the limitations of this as well).
-Some genes (and proteins) MAY accumulate mutations (changes) at a fairly constant rate (this is assumed)
-The more differences in the base sequences of a gene between organisms, the more time has passed since they diverged from a common ancestor (and vice versa too)
-The number of changes in base sequences of genes between organisms can be used as a “molecular clock” to determine the timing of divergence between them
Example: If the rate of mutation of a gene is 1 base pair change every 300,000 years and two species have 3 base pair differences in that gene, it can be deduced that they diverged (split) from a common ancestor 900,000 years ago
Limitations to this method/ model:
-Different genes/ proteins may mutate at different rates
-Genes may mutate at different rates in different organisms
-Over long periods, changes may be reversed (by later changes)
Compare gradualism vs. punctuated equilibrium
-Both describe the rate of evolution
-How fast speciation occurs depends on the type of reproductive isolation!
-generally accepted that both ideas take place in evolution
Gradualism
-gradualism suggests that evolution occurs over a long time
-gradualism changes are slow/steady over time
-gradualism would occur when there is little change in the environment
Punctuated Equilibrium
-punctuated equilibrium implies long periods with no change
-punctuated equilibrium implies short periods with great change
-punctuated equilibrium occurs when there are great changes in the environment;
-example; (eg: in times of volcanic activity/meteorite impact/great climate change)
Ploidy
refers to the number of copies of each chromosome a cell contains
Outline the process of polyploidy in plants.
-Haploid cells/ gametes (n) = monoploid (1 copy of each chromosome)
-Diploid/ somatic cells (2n) = diploid (2 copies of each chromosome - one set of copies from each parent)
-Polyploid cells (3n, 4n, 5n etc.) = three or more copies of each chromosome
-Polyploidy is more common in plants (than animals) and arises due to meiotic failure (and it can create a new species that is reproductively isolated after just ONE generation - sympatric speciation
-IF the resulting offspring are viable and fertile) - diploid gametes are produced and fuse, or diploid and haploid gametes fuse etc.
-More common in plants because they can self-fertilize or reproduce asexually via vegetative propagation
-Polyploid plants/ crops typically grow larger, have increased disease resistance/ longevity
-Farmers can also purposefully create seedless varieties of fruits utilizing polyploid methods that create infertile offspring (infertile = no seeds produced) - can be produced by treating crops with various chemicals
Allium
-Allium is a genus of flowering plants that include: onions, chives, garlic, and leeks
-Polyploidy in this genus has created many different, reproductively isolated species (sympatric speciation)
