Bio 2 Exam 2 Flashcards
What are the five mechanisms that cause evolution?
-Natural Selection
-Sexual selection
-Migration
-Inbreeding
-Genetic drift
What is macroevolution?
Evolutionary changes that create new species and groups of species
What is a species?
A group of related organisms that share a distinctive set of attributes in nature
What are distinguishing characteristics of a species?
-morphological traits
-reproductive isolation
-molecular features
-ecological factors
-evolutionary relationships
What is morphology?
Using physical characteristics to distinguish species.
Drawbacks of morphology?
-members of same species may look very different (poison tree frog color morphs)
-different species may look very similar (northern vs. southern leopard frogs)
What is reproductive isolation?
Prevents one species from successfully interbreeding with other species.
-ex. diversity in damselfly penis shape (isolation via lock and key fit)
What are molecular features?
Used to identify similarities and differences among different population.
-DNA sequences within genes
-gene order along chromosomes
-chromosome structure
-chromosome number
What are the drawbacks of molecular features?
Is a 2% difference in genomes between species enough of a difference to distinguish between species?
What are ecological factors?
Variety of factors related to an organism’s habitat
-ex. some of galapagos finches can only be distinguished by their island habitat
Drawbacks of ecological factors?
Ecological barriers can be hard to measure.
What are evolutionary relationships?
Phylogenetic trees based on fossils records or DNA
Drawbacks of evolutionary relationships?
Missing species (undiscovered, extinct). Many species and needed for robust estimates of evolutionary relationships.
What is biological species concept?
Emphasizes reproductive isolation as the most important criterion.
-“A group of individuals whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring but cannot successfully interbreed with members of other species” -Ernst Mayr
What is the evolutionary lineage concept?
Species should be defined based on the separate evolution in lineages (ex. line of descent)
What is the ecological species concept?
Each species occupies an ecological niche, which is the unique set of habitat resources that a species requires, as well as its influence on the environment and other species.
What does biological species concept use as a criterion for distinguishing species?
Reproductive Isolation
What are the two mechanisms that prevent interbreeding between different species?
-PREzygotic barriers
-POSTzygotic barriers
What are PREzygotic barriers?
Prevent formation of zygote (initial cell formed when a new organism is produced via sexual reproduction)
What are POSTzygotic barriers?
Block development of viable, fertile individuals (occurs after fertilization)
What are the five examples of prezygotic barriers?
-Habitat isolation: geographic barrier that prevents contact (e.g. finch species among galapagos islands)
-Temporal isolation: reproduce at different times of the day or year
-Behavioral isolation: behaviors important in mate choice
-Mechanical isolation: size or incompatible genitalia prevents mating
-Gametic isolation: gametes fail to unite successfully (important for species that release games in water or air)
What prezygotic barrier is the field cricket (one matures in spring and other in fall) catagorized in?
Temporal isolation
What is an example of behavioral isolation?
Western and Eastern meadowlarks. Both nearly identical, and for many years they were thought of as the same species. But very little interspecies mating takes place (largely due to differences in song)
What are the three examples of postzygotic barriers?
-Hybrid inviability: fertilized egg cannot progress past an early embryo
-Hybrid sterility: interspecies hybrid viable but sterile
-Hybrid breakdown: hybrids viable and fertile but subsequent generations have genetic abnormalities.
How do we categorize and name species?
Using taxonomy and systematics
What is taxonomy?
Science of describing, naming, and classifying living and extinct organisms
What is systematics?
Study of biological diversity and the evolutionary relationships among organisms, both extinct and modern
What is an example of binomial nomenclature (taxonomy) - Carl Linnaeus?
Common name: gray wolf
Species name: Canis lupus
When naming species what is capitalized?
Genus name
What is never capitalized when naming species?
Species epithet
When naming both name are italicized or underlined, true of false?
True
What is included at the end of a species name?
Author (scientific authority) and year of its description.
What does “sp.” mean?
epithet cannot be specified
What does “spp.” mean?
an abbreviation for several species
What is the formation of new species (mechanisms of speciation)?
Underlying cause of speciation is the accumulation of genetic changes that ultimately promote enough differences so that we judge a population to constitute a unique species.
What is an example of patterns of speciation?
Caldogenesis: splitting or diverging of a species into 2 or more species
– requires gene flow (movement of individuals, and/or the genetic material they carry, from one population to another) between populations to be interrupted.
What is allopatric speciation (patterns of speciation)?
-Occurs when some members of a species become geographically separated
What is the first example of allopatric speciation?
-2 porkfish species in the pacific and caribbean sea. Bother derived from a common ancestor that was separated by the formation of the isthmus of Panama
What is the second example of allopatric speciation?
Honeycreeper birds in Hawai’ian islands. Rosefinches from mainland migrated a founded populations on different islands. Single species evolved into array of descendants that differ greatly in habitat, form or behavior. This process is called adaptive radiation.
–Can also occur when small population moves to a new location that is geographically seperated.
What is allopatric speciation via hybrid zones?
Zones where two populations can still interbreed. Geographic isolation is not complete. Once gene flow through the hybrid zone is greatly diminished, the two populations are reproductively isolated.
What is sympatric speciation (patterns of speciation)?
Occurs when members of a species that are within the same range diverge into two or more different species even though there are no physical barriers to interbreeding
Why does sympatric speciation occur?
-Divergent adaptation to local environments (e.g. deep vs. shallow water)
-Sexual selection (e.g. diverging color preference by females)
-polyploidy
What is polyploidy?
When an organism has 2 or more sets or chromosomes
What is an example of polyploidy?
Diploid to a tetraploid through a mechanism like nondisjunction of chromosomes between plant species. Can occur through nondisjunction (autoploidy). An increase in number if chromosome sets resulting a viable yet reproductively isolated organism.
What can polyploidy lead to?
Can abruptly lead to reproductive isolation. Complex phenomena that can lead to hybrid sterility or viability depending of parental species. Plants are more amenable to this phenomena where 40-70% of ferns and flowering plants are polyploid.
What are the two factors that affect pace of speciation?
-Gradualism: each new species evolves continuously over long spans of time
-Punctuated equilibrium: short rapid bursts of changes followed by long periods of equilibrium
What is phylogeny?
Evolutionary history of a species or group of species
What is a phylogenetic tree?
A diagram that describes a phylogeny (hypothesis of evolutionary relationships)
What is a clade?
A group of organisms that are believed to have evolved from a common ancestor.
What is a node?
Indicates that a species diverged into 2 or more species
What is anagenesis?
Where a single species evolves into a different species
What is cladogenesis?
When a species diverges into 2 or more species
What is a monophyletic group?
A group that contains the most recent ancestor and all of its descendants
What is a paraphyletic group?
Contains a common ancestor and some, but not all of its descendants
-ex. reptilia does not include birds
What is a polyphyletic group?
A group with several evolutionary lineages but does not include the most recent common ancestor
-ex. moths and butterflies
True or false, taxonomic groups are often reorganized so only monophyletic groups are recognized?
True
What is homology?
A tool to combine and compare taxa and establish phylogenetic history.
–Similarities among various species that occur because they are derived from a common ancestor.
What is an example of morphological systematics?
Using horse teeth and foot bones to establish relationships and history
What is an example of molecular systematics?
Using DNA and comparing mutations can inform when sequencing diverged among taxa.
–Excellent approach with many homologous genes to compare
What are molecular clocks?
Longer period of time since their divergence allows fro greater accumulation of mutations. These accumulated differences allow for the estimate of time since divergence. Possible due to the constant rate of molecular evolution
What is an example of molecular clocks?
Cooper and colleagues extracted DNA from extinct flightless birds and extant species to propose a new phylogenetic tree. As a result, found that New Zealand was colonized twice by ancestors of flightless birds (once by moa and then by kiwi)
What is cladistics?
The study and classification of species based on evolutionary relationships (compares homologous traits or characters)
What is the purpose of cladistics?
Discriminate among multiple possible phylogenetic trees. It chooses the tree that requires the least complex explanation. This is achieved by considering the various pathways of evolutionary changes among traits (using sypanomorphic and symplesiomorphic traits)
What is synapomorphy?
Flippers (example) are a shared ancestral character with most recent common ancestor shared
What is symplesiomorphy?
Eyes (example) are a shared derived character inherited from ancestors older than last common ancestor.
What is the principle of parsimony?
Preferred hypothesis is the one that is the simplest for all the characters and their states
Order used to measure molecular clocks?
Favorable mutations are rare —> detrimental mutations eliminated —–> most mutations are neutral
-IF NEUTRAL MUTATIONS OCCUR AT A CONSTANT RATE THEY CAN BE USED TO MEASURE EVOLUTIONARY TIME
What is horizontal gene transfer?
Any process in which an organism incorporates genetic material from another organism without being the offspring of that organism
Molecular clocks (Hawaiian islands)
Birds and fruitflies have a linear relationship between genetic divergence and time when DNA divergence is plotted against island age. Species from oldest islands form the deepest branch of the phylogeny, and the younger islands on the tips of the tree
What is domain bacteria?
50 or so bacterial phyla structural and metabolic features of half are unknown. Amazing diversity of form and metabolism
What are proteobacteria?
Genera grouped under alpha, beta, gamma, delta, and epsilon
- Alpha ancestry of mitochondria can be traced with this group
What are some examples of gamma-proteobacteria?
- Neisseria (gonorrhea)
- Vibrio (cholera)
- Salmonela
- Escherichia coli
What is cyanobacteria?
Abundant photosynthetic bacteria
-The only prokaryotes that generate oxygen as a product of photosynthesis (gave rise to plastids of eukaryotic algae and plants.
-Display the greatest structural diversity found among bacterial phyla (fotm single cells to colonies or filaments)
True or false, cyanobacteria can cause many kinds of nuisance growths that form blooms?
True
What are thylakoids (cyanobacteria)
Ingrowths of plasma membrane that increase surface area for photosynthesis
What are magnetosomes?
Magnetite crystals that are compass like and helps to locate low-oxygen habitats
What are the common cell shapes?
-Cocci (spheres)
-Bacilli (rods)
-Vibrios (comma shaped)
-Spiral shaped
What is mucilage?
Comped of polysaccharides, protein, or both. Function to evade host defenses and biofilms.
What is gram positive bacteria?
Vulnerable to penicillin and interferes with peptidoglycan synthesis of outer layer, which stains purple
What is gram negative bacteria?
Resistant to penicillin and less peptidoglycan and more lippolysaccharides, which stains pink
What is the purpose of flagella?
Use of swimming. Different from eukaryotic flagella (like an outboard boat motor). Differ in number and location of flagella
What is Pili?
Twitch or glide across surfaces. Threadlike cell surface structures.
What is binary fission?
Type of reproduction. Divide by splitting in two
What are akinetes?
Food filled and develops when winter approaches.
What are endopores?
Amazingly long dormant span. Tough protein coat.
What are the three examples of obtaining/acquiring genetic material?
- Transduction: via viral vector
- Transformation: via uptake of DNA in environment
- Conjugation: via mating with another cell
What is the carbon cycle?
Producers synthesize organic compounds used by other organisms as food. Decomposers (saprobes) break down dead organisms to release minerals for reuse.
-ex. methanogens make methane and methanotrophs consume methane
What is a symbiotic relationship?
An organism that lives in close association with one or more other organisms
-ex. mutualism: association beneficial to both partners
What is domain archea?
Have features in common with the eukaryotic nucleus and cytoplasm (suggesting common ancestry)
-Distinctive feature=membrane linkages different from those in eukaryotes or bacteria (resistant to heat and other extreme conditions)
What are some differences between bacteria and archea?
- Cell membrane - archea cell membrane lipids feature ether linkages. Bacteria cell membrane lipids feature ester linkages.
- Location - archea are extremophiles while bacteria are found everywhere
Common ancestor of bacteria and archaea?
Evolved from common ancestor. Eukaryotic nucleus and cytoplasm likely arose in an ancient archea.
-Mitochondria originated from proteobacteria
-Plastids originated from cyanobacteria
What are protists?
Eukaryotes/all things with a nucleus that is not classified as a plant, animal, or fungi.
What are the two common characteristics of protists?
- Abundant in moist habitats
- are microscopic
What are the three major types of protisits?
- Algae (photoautotrophic)
- Protozoa (heterotrophic)
- Fungus-like (resemble fungi in body form and absorptive nutrition.
What are plankton (protists classified by habitat)?
Swimming or floating.
1. phytoplankton=photosynthetic
2. prtozoan plankton=heterotrophic
What are periphyton (protists classified by habitat)?
Communities attached by mucilage to underwater surfaces and produce multicellular bodies
What are protists classified by motility?
Swim using flagella, cilia, or pseudopodia
What are the seven supergroups of protists?
Excavata, land plants and relatives, alveolata, stramenopila, rhizaria, amoebozoa, and opisthonkonta
What is supergroup excavata?
- Named for food collecting groove that is excavated into the cell. Food is then taken into the cell via phagocytosis
- Parasites (Trichomonas vaginalis and Giardia lambia)
- Once thought to lack mitochondria
- MALARIA
What is supergroup of plants and relatives?
Kingdom plantae (land plants) evolved from green algal ancestors.
- 4 major phyla only focus on green and red algae
What is green algae (phylum chlorophyta)?
Occur in fresh water, oceans, and land. Cells contain same type of plastids and photosynthetic pigments present in land plants
What is red algae (phylum rhodophyta)?
Most are multicellular marine macroalgae. Red appearance due to distinctive photosynthetic pigments (cell walls impregnated with calcium carbonate = pink coloration)
What is supergroup amoebozoa?
Use by extension of pseudopodia
What is supergroup opisthokonta?
Includes animal and fungal kingdoms and related protists. Named for single posterior flagellum on swimming cells.
- Choanoflagellate protists (distinctive collar surrounding flagella)
- Modern protists most related to the common ancestor of animals
What are the reproductive adaptations of protists?
Asexual reproduction - all protists can reproduce asexually (repeated mitotic division)
- Many produce cysts with thick, protective walls than remain dormant
What is protists sexual reproduction?
Eukaryotic sexual reproduction with gametes and zygotes arose among the protists. Generally adaptive because it produces diverse genotypes
- Large diversity of life cycles (zygotic, sporic, gametic, ciliate sexual reproduction, parasitic)
What is the zygotic life cycle (protists)?
Generalized life cycle with haploid cells developing into gametes
What is ciliate sexual reproduction (protists)?
Most complex sexual process in protists
What is the parasitic life cycle (protists)?
Plasmodium (malaria) Parasitize more then one host organism. In which different life stages occur. Sex occurs in mosquito, asex occurs in humans
Origin and ancestry in plants?
multicellular eukaryotic organisms composed of cells having plastids.
What are charophycean algae?
share several derived traits with land plants.
- distinctive type of cytokinesis (cell division)
- plasmodesmata (intercellular connections)
- sexual reproduction using egg and smaller sperm
What are distinctive features in plants?
- Bodies composed of 3D tissues. Helps avoid water loss and early precursor to adaptation to land. Tissues arise from apical meristems at growing tips
- tissues and organs with specialized functions. Distinctive reproductive features. Alternation of generations between two types of body forms. Gametophyte=dispersal-form (genetically haploid). Sporophyte=plant-form (diploid)
What is the evolutionary history of land plants?
origin of land plants essential to the development of: substantial soils, evolution of modern plants, animals colonizing land
What are the three major stages in the evolutionary history of land plants?
- First land plants arise from ancestors shared with aquatic charophycean algae and begin to adapt to terrestrial habitats
- Seedless plants transform Earth’s ecology
- Ancient cataclysm led to the diversification of modern angiosperm lineages
Stage 1 First Plants
Land plants inherited some traits from charophycean algae. Novel features due to stress on land. Tissue-producing meristems, a sporic life cycle, tough-walled spores, and the sporophyte generation.
Stage 2a Seedless plants transformed Earth’s ecology
Liverworts and mosses produce decay-resistant body tissues and store CO2. Modern bryophytes also store CO2—-> grow, die, accumulate—> generating large peat deposits
Stage 2b Ecological effects of vascular plants
- Carboniferous plants converted huge amounts of atmospheric CO2 into decay-resistant organic material (ligen)
- proliferation of carboniferous vascular plants correlates with a dramatic decrease in atmospheric CO2 —-> which reached the lowest known levels about 290 million years ago
Stage 3 Rise of the angiosperms
About 65 mya, at least one large meteorite or comet crashed near Yucatan Peninsula in Mexico. Surviving flowering plants (angiosperms) diversified into space left
What are brtophytes?
liverworts, mosses, and hornworts each form a monophyletic phyla, and are the simplest of land plants
What is a bryophyte life cycle?
Sporific life cycle (alternation of generations). Allows a single plant to disperse widely by using meiosis to produce numerous, variable (haploid) spores. Each spore can grow into a gametophyte
What are bryophytes distinguishing features?
- Nonvascular plants (lacking tissues for structural support and water conduction found in other plants)
- No specialized tissue —> no true leaves, stems, or roots
- Plants cannot retain water or deliver it to other parts of the plant body (no xylem (water) or phloem (nutrient) systems
What are lycophytes and pteridophytes?
Vascular plants that do not produce seeds. Possess tracheids (elongated cells) for water and mineral conduction and structural support. Vascular tissue in stems, roots, and leaves
Lycophytes and Pteridophytes life cycle?
Reproduction is limited by dry conditions. If fertilization occurs, can produce many more spores due to their larger sporophyte generation.
Lycophytes and Pteridophytes function of stem, roots, and leaves.
- Leaves: photosynthetic function
- Stomata on leaves: used for gas exchange
- Stems: contain vascular tissue and produce leaves and sporangia (organs for storing spores) —> contain phloem and xylem
- Roots: specialized for uptake of water and minerals from the soil
What are characteristics of gymnosperms?
- produce seeds that are exposed rather than enclosed in fruits
- Most modern forms are woody shrubs or trees
- seeds and wood
What are progymnosperms (gynosperms)?
- first wood
- vascular tissue in a ring —> produces vascular cambium and wood
- reproduced by means of spores, not seeds
- wood came before seeds
What is phylum cycadophyta?
- leaves are palm like
- primarily found in tropical and subtropical locations
- roots are above ground and resemble corals
- harbor cyanobacteria for nitrogen fixation
What is phylum ginkgophyta?
- ginkgo biloba –> single remaining species
- individual trees produce either ovules and seeds, or pollen (dioecy)
What is phylum coniferophyta?
- Mature pollen released in the wind
- seed coats may have wings for dispersal
- wood contains tracheids for water transport
- valve like torus to prevent spread of air bubbles
- resin ducts (prevent attack from pathogens and herbivores - amber is fossilized resin)
Phylum coniferophyta cold climate adaptations
Flexible needle-shaped leaves. Most conifers are evergreens (leaves live for more than 1 year and do not seasonally shed)
What is phylum gnetophyta?
Only one living species found ing the coastal Namib Desert in SW africa. Long taproot and 2 very long leaves (shred over time). Obtains water from coastal fog.
What are flowering plants?
Seeds enclosed in an ovule (tomatoes, apples)
What are conifers?
Unprotected seeds (not enclosed in an ovule; pine trees)
What are ferns?
without seeds
What are angiosperms?
-defining feature are flowers, fruits, and endosperm (surrounds the embryo and provides nutrition in form of starch but can also contain oils and protein)
What are flowers?
complex reproductive structures specialized for efficient production of pollen and seeds.
Which parts of the flower are fertile?
- stamen = anther and filament
- pistil = stigma, style, ovary, and ovules
Which parts of the flower are sterile?
- Perianth = petal and sepal
- Receptacle
Peduncle
What is the evolutionary history of plants?
Flowers first appeared 140 mya. Flowers were a critical innovation that led to explosive angiosperm diversification
– Key even 65mya —> surviving flowering plants diversified into space left.
What is the stamen?
pollen-producing reproductive organ
What is the evolution of the stamen?
Early flowers had broad leaf-shaped stamens. Evolved a narrowed form to shape filaments and anthers (clusters or microsporangia producing pollen)
What is a carpel?
Modified leaves bearing ovules with a sticky surface
What is the evolution of the carpel?
Also evolved from leaf-like structures —> leaf folded to protect ovules
What are the early lineages of angiosperms?
Early diverging angiosperms represented by a single species Amborella trichopoda —> fairly small flowers, stamens with broad filaments, also lacks vessels
What are monocot and eudicot lineages?
- Monocots (1 embryonic leaves) and eudicots (2 leaves) are named for differences in number of embryonic leaves (first leaves) called cotyledons
What is flower diversification?
3 changes fostered the effective transfer of pollen
1) clustering of flowers into groups (called inflorescence) 2) reducing the perianth—> non reproducing part of the flower
3) floral tubes and coevolution with pollonators
What are fruits?
Develop from the ovary walls and aid the dispersal of enclosed seeds
Gymnosperm fruit vs. angiosperm fruit
-Gymnosperm: not a true berry but a cone with fleshy scales (seed not enclosed)
-Angiosperm: a true berry formed by ovary after flowering (seed enclosed in ovary)
What is secondary metabolites (angiosperm)?
Synthesis of molecules that are not essential for cell structure and growth. Three major classes in plants.
- terpenes and terpenoids
- phenolics (flavonoids and related compounds)
- alkaloids
What are terpenes and terpenoids?
largest scale of plant secondary compounds that are aromatic. Ex. citronella, rubber, turpentine, rosin, and amber
What are phenolics (flavonoids and related compounds)?
Some flower and fruit colors. Ex. flavors cinnamon, nutmeg, ginger, clove, chilies, vanilla
What are alkaloids?
Potent effects on animal nervous system. Ex. caffeine, nicotine, morphine, ephedrine, cocaine, and codeine
What is coevolution?
Process by which two or more species of organisms influence each other evolution. Ex. pollinators foster genetic variability and increase the potential for evolutionary change
Human influence on angiosperms?
Teosinte (corn prior to domestication) has “shattering” ears —> shattering is when wild fruit breaks apart and disperses seeds —> humans selectively removed this trait to make it easier to harvest
What is crop or vavilovian mimicry?
A weed that evolves to share one or more characteristics with a domesticated plant through generations of artificial selection
