Evolution and Taxonomy Flashcards
4 Purposes of Classification
- Identify and compare based on recognized characteristics
- Organized global system
- Compare organisms to predict evolutionary links
- Systematic collection and classification of information
4 Characteristics for Classification
Physical appeareance, behavior, biochemical characteristics, physiological characteristics
Phylogenetic Classification
Classifying organisms based on their differences and similarities on a genetic level
Hierarchy of Classification
Domaine, kingdom, phylum, class, order, family, genus, species
7 Phyla of Animal Kingdom
Porifera, cnidarian, platyhelminthes, annelida, mollusca, arthropoda and chordata
Phylum of Animal Kingdom: Porifera
Sack liked body with onelarge opening at the top, many tiny pores, no distinct tissues, live attached to the bottom of the sea floor
Phylum of Animal Kingdom: Cnidarian
Soft, sack like with one opening, opening surrounded by tentacles containing stinging cells (cnidae)
- Medusa form: tentacles hang down
- Polyp form: tentacles face up
Phylum of Animal Kingdom: Platyhelminthes
Flatworms: flattened dorsoventrally, bilateral symmetry, ring like divisions instead of segments, incomplete digestive system (mouth is anus)
Phylum of Animal Kingdom: Annelida
Segmented worms, cylindrical or slightly flattened, setate (tiny hair projections) for locomotion, bilateral symmetry, complete digestive system
Phylum of Animal Kingdom: Mollusca
Soft and slimy body, muscular foor for locomotion, partial shell or hinged shell that opens
Phylum of Animal Kingdom: Arthropoda
Insects.
- Jointed legs
- Tough chitin exoskeleton
- Shell that doesn’t open
- Head with well developed mouth and jaw
- Bilateral symmetry
Phylum of Animal Kingdom: Chordata
Bilateral symmetry, notochord present, head with developed mouth and jaw, visible eyespots
5 Classes of Phylum Chordata
Fish, amphibian, reptile, bird and mammal
Tetrapod
4 limbs
Class of Phylum Chordata: Fish
Scales, obtains oxygen dissovled in water through gills, external fertilization, only one type of teeth, no pentadactyl limbs (fins), ectothermic (body temperature depends on the environment)
Class of Phylum Chordata: Amphibian
Moist and highly permeable skin that conducts gas exchange alongside gills and/or lungs, either external or internal fertilization, vomerine teeth (only upper front jaw), four pentadactyl limbs, ectothermic
Class of Phylum Chordata: Reptile
Thick, scaly skin, shed periodically, lungs, internal fertilization, amniotic leather shelled egg, one type of teeth, tetrapod, ectothermic
Class of Phylum Chordata: Birds
Feathered, lungs, internal fertilization with a calcium carbonate shell, no teeth: bills, tetrapod (2 wings), endothermic
Class of Phylum Chordata: Mammal
Hairs on skin, lungs, internal fertilization, tetrapod, endothermic
4 Phyla of Plantae Kingdom
Bryophytes, filicinophytes, coniferophytes, angiospermophytes
3 common characteristics of all members of the plantae kingdom
Multicellular, have a cellulose cell wall, mostly autotrophs
Bryophyte Phylum of Plantae Kingdom
No vascular tissue (xylem or phloem), short in height, no flower or seeds covered by fruit, sperm cells swim towards the egg to fertilize, spores.
Have no roots, only rhizoids. Simple leaves or thalli. Must live in moist habitats, as substances are moved through osmosis and diffusion from surface moisture and sperm swims towards egg.
Rhizoid
Hair like projections that grow directly out of the photosynthetic tissue of bryophytes.
Thallus (thalli)
Plant bodies not distinguished into stem, leaf or root
Spore
Haploid cells that undergo mitosis to develop into new organisms
Vascular Plants
- Have roots, stems and leaves
- Have vascular tissues: xylem and phloem
- Have xylem vessels with the stiffening agent lignin to grow taller
- Include seedless plants (filicinophytes) and seed plants (coniferophytes and angiospermophtes)
Filicinophyte Phylum of Plantae Kingdom
- Leaves are often pinnate
- Must live in moist habitats since the sperm cells have to swim through water to fertilize the egg
- Have haploid spores, visible in clusters called sori on the underside of leaves
Pinnate
Fronds with leaflets on each side of a common axis
Seed Plants
Coniferophytes and angiospermophytes. Produce pollen and seeds, dispersed by wind or pollinators. Eliminate the need for sperm to swim to the egg: don’t need moist environment, can grow high. Seeds are diploid cells, protected by a seed coat and nourishes the plant before it can undergo photosynthesis.
Coniferophytes
- Have roots, stems and leaves
- Leaves usually evergreen, don’t drop seasonally
- Leaves are needle shaped and have waxy cuticle to limit water loss
- Have vascular tissue: can grow tall
- Have woody stems and produce seeds in cones
Angiospermophytes
- Have roots, stems and leaves
- Flowering
- Have vascular tissue
- Reproduce seeds produced from ovules within flowers
- Produce seeds in fruits
Cladogram
A tree diagram representing the most probable sequence of divergence within a group that shares characteristics
Challenges of Cladogram Creation
Mostly based on sequences analysis of either DNA bases or AAs from proteins. However, DNA cannot be extracted from fossils. The orders are interpreted using incomplete information.
Cladogram vs Phylogenetic Tree
Cladogram doesn’t have a timeline; phylogenetic trees do.
Cladogram Interpretation
- A clade includes a common ancestor and all of its descendants
- Each line represents a separate species
- A line shorter than the others represents an extinct species
- At least one derived characteristic is needed to separate each branch from the others
- The more nodes there are between species, the more distance their relationship
- Length of branches within a cladogram aren’t proportional to the time since divergence
Errors in Classificaction: Figwort Classification
Originally classified based on shared morphological features, changed by DNA sequence analysis.
Aristotle’s Ladder of Life
Organisms categorized by order of importance
Lamarckism
Survival requires adaptation to the environment. Species cannot evolved into new species. Species become more complex while simple species are spontaneously generated.
- Acquired traits can be inherited
Darwin’s Theory of Natural Selection
Traits that allow an organism to better adapt to the environment allow it to live to an age where it successfully reproduces and passes the traits to its offspring. Changes in allele frequency as advantageous traits become more commmon in a population
Thomas Malthus
In nature plants and animals produce far more offspring than the amount of resources available for each organism.
Graph
- Amount of resources is linear
- Population increases exponentially
- Point of intersection is the point of crisis
4 Factors of Natural Selection
- Competition: inter and intraspecies compete for limited resources
- Variation: natural variaiton in the pre - existing gene pool, with some traits naturally more advantageous than others
- Changing environment that doesn’t stay static. As it changes, the advantageous traits would change in response
- Randomness: the changes elicited by the changes in the environment are random
Fitness
The average number of offspring left by an individual relative to the number of offspring left by an average member of the population. Whoever has the most reproductive success would be the fittest.
Antiobiotics Mechanism
- Antibiotics target bacterial cells through components human cells don’t have
Antibiotic Resistance
- A resistant variety emerges within normal ones
- Come in contact with antibiotics, the normal bacteria die off, leaving the resistant strain
- Resistant strain multiply
- Each time antibiotics are applied, more and more normal bacteria killed, resistant left
- Emergence of a new strain of bacteria
3 Types of Selective Pressures
- Disruptive
- Stabilizing
- Directional
Disruptive Selective Pressure
Selection against the mean splits the population, often leads to speciation
Stabilizing Selective Pressure
Selection against both extremes, favoring the average trait
Directional Selective Pressure
A force in nature causes a popoulation to evolve towards one end of a trait spectrum. A trait that becomes advantageous over time propels this change. Can result in speciation
Coevolution
The prey and the predator engage in an evolutionary arms race, constantly readjusting their biological makeup in response to changes taking place in one another.
Symbiotic Relationship
Two species that aid each other in mutual survival
Speciation (6 Step Process)
- Genetic variation present, inheritable
- Competition for survival
- Environmental selective pressures lead to differential reproduction
- Fitter organisms mroe likely to survive and reproduce
- Over generations a change in allele frequency within a population emerges
- Organisms that become reproductively isolated can diverge over time, forming a new species
Species Definition
Organisms that can interbreed with each otehr under natural conditions
Hybrid Definition
Offspring of organisms from different species, cannot be born under natural circumstances
5 Modes of Reproductive Isolation
Geographical, temporal, behavioral, gamete and mechanical isolation
2 Types of Reproductive Isolation
- Allopatric: differing geographical location
- Sympatric: populations split into separate gene pools but continue to share a similar geographic location
Mode of Reproductive Isolation: Geographical Isolation
Allopatric: differing habitats result in different advantageous traits, species becoming more and more different as different traits are passed on
Mode of Reproductive Isolation: Temporal Isolation
Mating time don’t match
Mode of Reproductive Isolation: Behavioural Isolation
Differing mating behavior
Mode of Reproductive Isolation: Gamete Isolation
Incompatible gametes: differing number of chromosomes: polyploidy. Not common in animals, more common in plants
Mode of Reproductive Isolation: Mechanical Isolation
Physical differences that prevent pollination or copulation
2 Modes of Speciation
Gradualism and punctuated equilibrium
Mode of Speciation: Gradualism
A consistent progression of speciation, with slow and constant change. Small variations taht fit an organism slightly better to its environment are selected for, including intermediate species
Mode of Speciation: Punctuated Equilibrium
Long periods of little change followed by short periods of rapid change. Often through the mutations in the genes of few individuals. Changes occur rapidly over few generations.
Microevolution
Change in gene frequency within a population, during short periods of time, e.g. between one generation and the next
Macroevolution
Generally above the species level, longer periods of time. Can lead to speciation
Evidence for Evolution: Fossil Record
- Forms when organisms become compressed in layers of sediment from rock or sand
- Requires a series of specific circumstances to occur by chance, which rarely occurs
- Older fossils in deeper layers and less complex
Radiometric Dating
Measures the presence of a short - life radioactive material to determine the age of the fossil
Evidence for Evolution: Embryological
The more closely related the organisms are, the more recent the common ancestor and the longer the embryos look alike
Evidence for Evolution: Biochemical
All living organisms share
1. Same nucleotide base pairs
2. Same DNA
3. Same/ highly similar codons
4. Same molecular building blocks: amino acids
- Homologous genes are compared between species to discover their evolutionary relationship
- The less time since two species diverge from a common ancestor, the less differing amino acids
- DNA changes faster than protein sequences, changes at a constant rate
Evidence for Evolution: Selective Breeding
An individual determines which traits are desirable, not the environment. Selected traits become more and more common in the offspring. Limits genetic diversity, increasing probability of recessive genetic diseases
Evidence for Evolution: Anatomical
Homologous, analogous and vestigial structures that suggest divergent and convergent evolution
Divergent Evolution
Closely related groups develop different outward appearances or traits. Have a common ancestor, often leads to features or traits no onger needed
Homologous Structures
Similar internal structures with differing function, e.g. the pentadactyl limb. Evidence of divergent evolution.
Vestigial Structures
Similar structure, no function. Still exist because there’s no advantage in getting rid of it, takes time to evolve out of and isn’t actively detrimental or high maintenance
Convergent Evolution
Distantly related groups develop similar outward appearances or traits. Similar looking animals on different continents, with different ancestors
Analogous Structures
Differing structure, similar function
Evidence for Evolution: Biogeographical
Species are often more similar to species living nearby than to those living in similar environmental conditions further away.
- Tend to share analogous traits
Endemic Species
Species that only exist in one locaiton. Endemic species on islands are often similar to mainland species. However, the older the island, the longer the period of separation, the greater the amount of time for the species on the island to experience different environmental conditions and evolve more. Thus, the greater the chance for new species to evolved and become endemic.
Evidence for Evolution: Biomolecular
Non coding regions are free to accumulate mutations. Scientists can use the variations accumuated, often of mitochondria, to determine the approximate time of a divergence between organisms.
Transient Polymorphism
Gradual change in the allele frequency of a population due to the slow replacement of one gene of another
Balanced Polymorphism
Balance between both forms of the allele variations within a population
6 Modes of Changes in Allele Frequency
- Natural selection
- Mutations
- Non - random mating
- Gene flow
- Genetic drift
- Gamete isolation
Mode of Changes in Allele Frequency: Mutation
Random changes in genes that lead to the creation of different traits
Mode of Changes in Allele Frequency: Non - Random Mating
Individuals, usually females, choosy in their selection of mates. Often traits that help in sexual selection come at a cost to the organism
Mode of Changes in Allele Frequency: Gene Flow
Movement of new alleles into an existing gene pool throguh immigration or migration. Individuals may mate with an organism of the same species but different population
Mode of Changes in Allele Frequency: Genetic Drift
Changes in a population’s allele frequency due to chance alone. More likely to affect smaller populations when random events occur. Significant decrease or increase of a population size that result in more organisms with a particular trait surviving
Founder Effect
- Few individuals start a new population with a different allele frequency than the original population
- May lead to speciation
Bottleneck Effect
- A population’s size is rapidly reduced for at least a generation
- So little survivors to the catastrophe that there is less variation
Mode of Changes in Allele Frequency: Gamete Isolation
- Polyploidy
- More than two paired sets of chromosomes
- Mitotic errors or non - disjunction in meiosis
- As mutations accumulate a new species forms
Classification of Humans
Domain: eukarya
Kingdom: animalia
Phylum: chordata
Class: mammalia
Order: primate
Famild: hominid
Genus: homo
Species: sapiens
Hominoids
Common ancestor of the gibbons, gorillas, cimpanzees, organgutans and humans
Hominids
Humans and their extinct lineage
8 Characteristics of Hominids
- Increased brain size
- Increased forehead size
- Bipedal posture
- Shorter, less powerful arms
- Stronger and longer legs
- Flatter faces
- Shorter, duller canine teeth
- Reduced size differences between sexes
