topic 5 - evolution Flashcards
what is evolution?
a change in the allele frequency of a population’s gene pool over successive generations
what is Lamarck’s theory of evolution?
species change via habitual use and disuse (ex. giraffe stretches its neck to reach leaves in tall trees, so giraffe’s neck becomes extended from constant use and its offspring inherit its long neck)
rejected, as acquired traits do not have a genetic basis (can’t be inherited)
what is Darwin (and Wallace)’s theory of evolution?
species change via natural selection
(ex. giraffe with a longer neck can reach leaves in tall trees, so it will get enough food to survive and reproduce so it has more offspring that inherit a long neck)
reinforced by our understanding of modern genetics
what is a fossil
preserved remain or trace of a past organism
what is the fossil record
totality of all fossils
how can fossils be dated
by determining the age of the rock layer (strata) in which te fossil is found
what is the law of fossil succession
the chronological sequence of complexity by which characteristics appear to develop (basically changes have occured in organisms and changes occured in consistent sequence of development)
what are transitional fossils
intermediary forms within the evolution of a genus and demonstrate species connections
what is an example of a transitional fossil
archaeopteryx links evolution of birds (wings and feathers) to dinosaurs (jaws and claws)
what is selective breeding
form of artificial selection
mating of animals with desired characteristics (driven by human intervention)
selective breeding promotes phenotype extremes: T or F?
true
example of selective breeding?
draf horses (power) vs racing horses (speed)
what are homologous structures
anatomical features that are similar in basic structure despite being used in different ways
Species A: 5 digit limbs
Species B: 6 digit limbs
Species C: 3 digit limbs
Species D: 5 digit limbs
Which two species are most closely related? RANDOM SITUATION
A + D
what is adaptive radiation?
Describes the rapid evolutionary diversification of a single ancestral line
what is an example of a homologous structure in a variety of animals?
pentadactyl limb of mammals, birds, amphibians and reptiles
mammals: tool manipulation
bird/bat wings: flying
horse hooves: galloping
whale/dolphine fins: swimming
what type of distribution curve does genetic variation typically follow?
normal distribution curve as the rate of change is gradual and cumulative
what is speciation
evolutionary process by which two related populations diverge into separate species
how does speciation occur?
populations become isolated, and hence the level of genetic divergence gradually increases the longer the populations remain separated (since genetic compatibility decreases)
populations will reach a point where they can no longer interbreed and produce fertile, viable offspring
what is an example of evolution in melanistic insects?
peppered moths
exist in two forms (light and dark colouration)
in polluted environments, SO2 kills the lichen on trees and soot blackens the bark, which provides camouflage for dark moths
before the industrial revolution, the lighter moth had a survival advantage (lichen is white)
after the industrial revolution, the dark moth has a survival advantage
what is biogeography
distribution of species across an area (related species will usually be found in close proximity)
what are vestigial structures
functionless or reduced remnants of organs that were once present in ancestors
ex. whales have a pelvic bone (ancestors were terrestrial)
how can the time of evolutionary divergence be estimated? (molecular clock) –> think of conditions
gene must have a stable mutation rate
what are the three main mechanisms by which genetic variation within a population is maintained?
mutations (changes to the gene sequence)
sexual reproduction (new gene combinations)
gene flow (immigration and emigration)
how can population variety be altered? (biodiversity down)
random chance (genetic drift) directed intervention (natural / artificial selection)
is the impact of a change greater on a large or small population?
SMALL (may occur via population bottle necks or founder effect)
why does natural selection occur? (list potential reasons)
- genetic (inheritable) variation within a population caused by mutations, meiosis, and sexual reproduction
- there is competition for survivale as species tend to produce more offspring than the environment can support
- environmental selection pressures give rise to differential rates of reproduction
- organisms with beneficial traits are likely to survive and reproduce while those less adapted produce less offspring
ICEAGE?
key components to the process of natural selection
Inherited variation, Competition, Environmental selection, Adaptations, Genotype frequency changes, Evolution occurs
what are examples of environmental selection pressures?
Predator / prey dynamics Abiotic factors (ex climate) Nutrient supply (food source) Diseases / pathogens Available resources (ex. light) Space requirements (habitat)
PANDAS
how does genetic variation occur through mutations?
new alleles are formed
can be beneficial, detrimental or neutral
beneficial: change the gene sequence –> new variations of a trait (missense mutation)
detrimental mutations: truncate the gene sequence (nonsense mutations) to abrogate normal function
neutral: no effect (silent mutation)
how does meiosis promote variation?
produces new gene combinations through either crossing over or independent assortment
what is crossing over
exchange of segments of DNA between homologous chromosomes during prophase I between nonsister chromatids at chiasmata
what is independent assortment
orientation of homologous chromosomes towards the opposing poles is random when they line up in metaphase I
orientation of each bivalent occurs independently, meaning different combinations of maternal/paternal chromosomes can be inherited when bivalents separate in anaphase I
how does sexual reproduction promote variation
random fertilization by egg and sperm generates different zygotes
what did Malthus identify?
Malthusian dilemma: populations multiply geometrically (exponential progression) while food resources only increase arithmetically (linear progression)
SPECIES TEND TO PRODUCE MORE OFFSPRING THAN THE ENVIRONMENT CAN SUSTAINABLY SUPPORT
what are adaptations
features of organisms that aid their survival by allowing them to be better suited to their environment
how can adaptations be classified?
structural: physical differences in biological structure (ex. giraffe neck)
behavioural: differences in patterns of activity (ex. opossums feigning death)
physiological: variations in detection and response by vital organs (ex. colour perception)
biochemical: differences in molecular composition of cells and enzyme functions (ex. blood groups)
developmental: variable changes that occur across the life span of an organism (ex aging)
do biological adaptations have a genetic basis? why or why not
yes, organisms with beneficial adaptations are more likely to survive and reproduce
what is an ecological niche
functional position of an organism in the environment
how are adaptive radiation and ecological niches related?
when members of a species occupy a variety of different ecological niches, it leads to the rapid diversification of the original ancestral line (adaptive radiation)
ex. beaks of finches on Daphne Major
is the variation that exists within a population heritable? if so, how is it determined?
yes, determined by the presence of alleles
how does the proportion of different alleles change due to natural selection?
beneficial alleles improve reproductive prospects and are more likely to be passed onto future generations
detrimental alleles result in fewer offspring and are less likely to be present in future generations
what is Daphne Major
volcanic island part of the Galapagos (native habitat of Darwin’s Finches)
how can bacteria develop antibiotic resistance via gene mutation?
resistant bacteria survives and reproduces by binary fission
flourishes in the absense of other strains of bacteria (that are killed b bacteria)
introduction of antibiotic caused the antibiotic resistant gene to become more frequent (evolution)
what is the binomial system of naming
globally recognized classification scheme developed at a series of congresses, proposed by Carl Linnaeus in 1735
how are organisms named according to the binomial system?/
two part name: Genus species genus is first + capitalized species is second + lower case must be underlined when handwritten
what are the three domains of life?
Eukarya
Archaea
Eubacteria
what are eukarya?
eukaryotic organisms that contain a membrane-bound nucleus
what are archaea
prokaryotic cells lacking a nucleus and consist of extremophiles
what are eubacteria
cells lacking a nucleus and consist of the common pathogenic form
T or F? Archaea and Eubacteria were always two separate domains
F. Initially both considered part of Monera
reclassified after biochemical differences were noted
what is taxonomy?
science involved with classifying groups of organisms on the basis of shared characteristics
what does it mean when organisms share a lot of taxa
the more taxa organisms share, the more similar they are
what are the taxa used?
kingdom phylum class order family genus species
Katy Perry Comes Over For Grape Soda
what are the two main classification schemes used to identify living organisms?
artificial classification
natural classification
what is artificial classification? (w/ one advantage + one disadvantage)
arbitrarily selecting unifying characteristics first and then grouping organisms accordingly
advantage: easy to develop + stable
disadvantage: do not show evolutionary relationships
what is natural classification (+ one advantage + disadvantage)
grouping organisms based on similarities first and then identifying shared organisms
advantage: can be used to predict characteristics shared by species within a group
disadvantage: highly mutable (may need to reclassify groups when new information/evidence arises)
characteristics of bryophyta?
- no vascularization
- no true leaves, roots, or stem
- reproductive stalks
- short
- ex. mosses, liverworts
characteristics of fiicinophyta?
- vascular
- no flowers
- triangular fonds
- reproduce through spores
- ex. ferns
characteristics of coniferophyta?
- vascular
- woody stems
- needles and scales
- reproduction through non-motile gametes (cones)
ex. cedar, juniper, fir, pine trees
characteristics of angiospermophyta?
- vascular
- flowering plants
- flowers and fruits
how is the kingdom Animalia subdivided?
invertebrates (no backbone)
vertebrates (backbone)
characteristics of porifera
- no body symmetry
- no mouth or anus
- pumping water in/out to filter out food
- stuck in place
- ex. sea sponges
characteristics of cnidaria
- mouth but no anus
- stinging cells
- tentacles
- ex. sea jellies
characteristics of platyhelminthes
- bilateral symmetry
- mouth but no aanus
- flattened body shape (SA:vol ratio up)
- nonsegmented
- ex. tapeworms
characteristics of annelida
- segmented
- mouth + anus
- ex. earthworm
characteristics of mollusca?
- mouth + anus
- non segmented
- shell reinforced with calcium
- ex. snails, clams, octopus
characteristics of arthropoda
- hard exoskeleton made of chitin
- segmented
- mouth + anus
- ex. insects, spiders
characteristics of chordata
- mouth + anus
- notochord + hollow, dorsal nerve
- ex. mammals, birds, reptiles
characteristics of fish?
- gills to absorb oxygen
- scales made of bony plates
- ecothermic
- external fertilization
characteristics of amphibian
- moist skin
- external fertilization
- start lives underwater (adults develop lungs)
- ectothermic
characteristics of reptiles
- scales made of kertain
- internal fertilization
- lungs with extensive folding
- ectothermic
characteristics of birds
- bipedal
- covered in feathers made of keratin
- internal fertilization + lay eggs
- endothermic
- light weight
- high heartbeat + breathing rates
characteristics of mammals?
- hairy bodies (hair made of keratin)
- females can produce milk in specialized glands
- endothermic
what is a dichotomous key?
method of identification whereby groups of organisms are divided into two categories repeatedly
what is cladistics?
method of classifying organisms into groups of species called clades
what is a clade
group of organisms that evolved from a common ancestor (share common characteristics)
what are cladograms
tree diagrams where each branch point represents the splitting of two new groups from a common ancestor
what is a node
branch point which represents a speciation event by which distinct species are formed via divergent evolution
what is phylogeny
evolutionary history
what does it mean when the number of nodes between two groups is small
they are expected to be more closely related
what type of relationship do cladograms show
evolutionary
features of a cladogram
root: initial ancestor
nodes: common ancestor that speciated
outgroup: distantly related species in cladogram
clades - common ancestor
how are molecular sequences used to determine how closely related two species are?
the more similar the base sequences of two species are, the more closely related the two species are expected to be
what are amino acid sequences typically used to compare?
different taxa
what are DNA/RNA base sequences often used to compare?
closely related organisms
what is the molecular clock + how does it work? (think of conditions)
when the rate of change (of mutations) of change is reliable / at a constant rate, scientists can calculate the time of divergence according to the number of differences
what are two limitations to using morphological differences as a basis for classification?
closely related organisms can exhibit very different structural features due to adaptive radiation
distantly related organisms can display very similar structural features due to convergent evolution
what is convergent evolution
independent evolution of similar features in species with distinct lineages
what are homologous structures
traits that are similar because they were derived from common ancestry
what are analogous structures
traits that are superficially similar but were derived through separate evolutionary pathways
how was the figwort family reclassified using cladistics?
many of the figwort plants were too dissimilar ins tructure to function as a meaningful grouping
the chloroplast gene was examined in figworts
figwort family was diveded into five clades
