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[h] IB DP Biology HL A4.1 Evolution and speciation Flashcards
[q]
What is evolution?
What is the mechanism of evolution?
[a] Evolution is a change in the heritable characteristics of a population; (of a particular species);
Over time;
[q]
What is the evidence for evolution from base sequences of DNA/RNA and amino acids?
[a]More closely related species share more similar DNA sequences; and therefore RNA sequences;
The smaller the differences in DNA/RNA and amino acid sequences, the more recently the organisms shared a common ancestor;
[q] What is selective breeding?
What is the evidence for evolution from selective breeding of animals?
Or crop plants?
[a] Selective breeding is when humans have selected for particular desired traits;
humans bred/mated those individuals that possessed the desired characteristic; e.g. more milk being produced;
this is done repeatedly, each time selecting and breeding only the organisms who best display the trait;
causing rapid changes in heritable characteristics through the generations;
this is evolution; through artificial selection;
[q]
What are homologous structures?
What is the evidence for evolution from homologous structures?
[a] Homologous structures are structures which may appear different, but have a common ancestral form;
have different functions;
but all came from the pentadactyl limb;
from a common ancestor;
each form evolving due to different environmental pressures;
this also explains vestigial structures;
which have no obvious function;
e.g. small thigh bone in whales;
[q]
What are analogous structures?
What is convergent evolution?
How does convergent evolution explain the existence of analogous structures?
[a] Analogous structures seem similar as they share the same function; e.g. wings in birds and insects are both used for flying;
Convergent evolution is the idea that the similar environments and selection pressures led to the development of the same adaptation;
[q] What is speciation?
[a] Speciation is when one species splits into two new species;
e.g. by geographical reasons;
different environments will cause different selection pressures;
leading to changes in the two populations;
eventually they will be unable to interbreed; and are now two different species;
[q]
What is reproductive isolation?
What is differential selection?
What are their roles in speciation?
[a] Reproductive isolation and differential selection are both required for speciation;
Commonly this is due to geographical separation; e.g. a mountain range separating them;
Differential selection is when there are different selection pressures in different environments, leading to particular adaptations being selected for; by natural selection;
Over time large differences in the adaptations selected for can occur, so that the populations become different species;
[q]
What are some examples of differential selection that could occur to two populations which are separated geographically?
[a] Different climates, different predators or prey, competition for resources, types of food sources available;
[q]
a population of worms in a grassy field includes green and brown worms. both the variations are eaten equally by birds.
a change in the environmental conditions has resulted in the vegetation drying up and the ground becoming bare.
predict how natural selection will work
[a] the birds can see the green worms more easily and a larger number of the green worms are eaten, increasing the proportion of brown worms
[q]
which of the following is an example of lamarckism?
[a] jackals hunt ostriches. ss they are chased by the jackals, the ostriches run fast and develop stronger legs. they pass on the trait to their offspring resulting in a population of ostriches that can run fast
[q]
a scientist collects the amino acid sequence data of several species. the scientist analyses the data. Identify a possible conclusion
[a] the more amino acids shared by two species, the more closely related they are in evolutionary time
[q] which of the following examples indicates convergent evolution?
[a] the flipper of a penguin and the pectoral fin of a shark
[q] which of the following is an example of geographical isolation leading to reproductive isolation?
[a] separation of populations of tree frogs due to deforestation
[q] a scientist comes across a population of insects. the scientist thinks it is a new species. which of the following would confirm that the insects are a new species?
[a] they are unable to mate with other similar species to produce fertile offspring
[q] male dolphins make clicking or whistling sounds to attract their mates. if the female dolphins cannot recognize this mating call, what could this lead to?
[a] behavioral isolation
[q] which of the following is an example of allopatric speciation?
[a] a volcanic eruption isolated a small population of species from the main population, preventing gene flow between the two populations
[q] which of the following gives correct definitions of the three types of isolation?
[a] temporal isolation: one species of fruit flies are sexually active early in the morning while the other species is active in the afternoon
behavioral isolation: the light patterns created by one species of fireflies are not recognized by another species
[q] an organisms with n=4 is a tetraploid. determine the chromosome number of the organism
[a] 16
[q] two different species interbreed and produce a fertile hybrid with additional sets of chromosomes.
which term best describes the organism produced?
[a] an allopolyploid
[q] speciation is the outcome of:
[a] reproductive isolation
[q] identify the example of convergent evolution
[a] the development of wings in birds and insects
[q] which of the following may result in geographic isolation?
[a] two populations occupy separate niches
[q] which of the following can increase biodiversity?
II. adaptive radiation
III. selective breeding
[a] I and II only
[q] identify how selective breeding differs from natural selection
[a] selective breeding may lead to rapid changes in the genetic make-up of a population
[q] which of the following is the cause of the differences between the bonobos (pan paniscus) and common chimpanzee (pan troglodytes)?
[a] differential selection
[q] identify why selective breeding of crops is important
[a] it gives varieties that have an increased yield
[q] wich of the following scenarios would not contribute to allopatric speciation?
[a] gene flow between the two populations is extensive
[q] leopard frogs and wood frogs reach sexual maturity at different times in the spring and hence cannot interbreed. what is this is an example of?
[a] temporal isolation
[q] which of the following may be used as evidence for evolution:
II. selective breeding of domesticated animals
III. overproduction of offspring
I. non-disjunction
II. multiple genes
III. multiple alleles
[q] which of the following provide evidence for evolution?
II. RNA sequences
III. amino acid sequences
[q] What are homologous structures and how do they support the theory of evolution?
[a] Similar structures in species that share a common ancestor yet are now separate. They support evolution because similar structures give the idea that two separate species may have once been one and the same.
[q] What are analogous structures?
[a] Similarities in structures that have become similar because the organisms have adapted to similar environments
[q] How does geographic distribution support the theory of evolution?
[a] Organisms on separate parts of the world shared traits because of biogeography and convergent evolution.
[q] What is convergent evolution?
[a] When species who evolved separately develop similar traits because they are adapting to similar environments.
[q] What is divergent evolution?
[a] When one species evolves in two different directions due to experiencing separate environments.
[q] What are vestigial structures and how do they support the theory of evolution?
[a] Vestigial structures are remnants of structures that no longer serve a purpose, ex. the appendix and the muscles that give us goosebumps. They support evolution because they show that we used to have a function for them but evolved to no longer require them.
[q] What is artificial selection?
[a] Selective breeding. Choosing the best crop and using that, or choosing the best/most fit dogs and breeding them.
[q] What is molecular evolution?
[a] The DNA of species can be tested to check for similarities with other species. The evolution of DNA leads to new species.
[q] What are the two main points of Darwin’s theory?
[a] That natural selection occurs and that there is descent with modification.
[q] What are the four principles of natural selection?
[a] First, that organisms produce more offspring than can be supported by the environment.
Second, that offspring are not identical and there is variation within a population.
Third, individuals compete for resources.
Fourth, the individuals that are more successful at obtaining food, territory, and mates will have a better chance of survival and therefore more offspring.
[q] What causes variation in a population?
[a] Genetic mutations, meiosis (the combination of new alleles), and sexual reproduction.
[q] What does survival of the fittest mean?
[a] Fittest = the ones with the most reproductive success, not necessarily the biggest or the strongest. The most fit have the most offspring and pass on their genes.
[q] What is descent with modification?
[a] Over many generations, adaptations could cause species to evolve into new species; all species are descended from a common ancestor.
[q] Can an individual evolve?
[a] No.
[q] What is the smallest group of organisms that can evolve?
[a] A population, which is a group of individuals of the same species in the same area at the same time.
[q] What is a gene pool?
[a] The total number of genes in a particular population.
[q] What is genetic equilibrium?
[a] When all members of a population have an equal chance of contributing to the future gene pool (doesn’t actually happen in nature).
[q] What four things cause changes in gene pools?
[a] Natural selection, reproductive isolation, random events (genetic drift, like a natural disaster), and mutations introducing new alleles.
[q] What are the three patterns of natural selection?
[a] Stabilizing, disruptive, and directional.
[q] What is stabilizing natural selection?
[a] When natural selection removes the extremes from the population and goes toward middle ground.
[q] What is disruptive natural selection?
[a] When natural selection moves toward the extremes and away from the average.
[q] What is directional natural selection?
[a] When natural selection moves toward one extreme that is better adapted to the environment.
[q] What is reproductive isolation?
[a] When populations become isolated from one another and can no longer reproduce together.
[q] What are the four types of reproductive isolation?
[a] Geographical (physically), temporal (mating times are misaligned), behavior (mating behavior is dissimilar), or anatomical (sexual organs are incompatible).
[q] What is speciation?
[a] When two populations separate and evolve into separate species.
[q] What is allopatric speciation?
[a] When two populations are separated by a physical barrier and evolve into separate species that can no longer reproduce with each other.
[q] What is sympatric speciation?
[a] Behavior, temporal, or anatomical reproductive isolation.
[q] What is plant speciation?
[a] Plants can evolve through polyploidy (contributing extra chromosomes, typically an entire set).
Often produces a species that is reproductively isolated and distinct from “parent” species.
[q] What are the two theories of evolutionary change?
[a] Gradualism, a slow even change; or punctuated, long periods of no change with bursts of rapid change.
[q] What are the three domains and what are their characteristics?
[a] Bacteria, unicellular and prokaryotic, cell wall w/ peptidoglycan;
Archaea, unicellular and prokaryotic, cell wall w/o peptidoglycan; Eukarya, eukaryotic
[q] What are the six kingdoms and what are their characteristics?
[a] Bacteria, unicellular organisms; Archaea, unicellular organisms in extreme environments;
Protista, unicellular complex organisms; Fungi, uni/multicellular and absorb food;
Plantae, multicellular and make their own food; Animalia, multicellular and consume their food.
[q] What is the hierarchy of classification and what is the mnemonic device?
[a] Dear King Philip Came Over For Great Soup! (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
[q] How are humans classified?
[a] [D]-Eukarya, [K]-Animalia, [P]-Chordata (hollow nerve chord), [C]-Mammalia (middle ear bone, hair, milk production), [O]-Primates (opposable thumbs, fingernails, expanded forebrain, binocular vision), [F]-Hominidae (no tails, ex. chimpanzee), [G]-Homo (tool use, language, culture), [S]-Homo sapiens
[q] How do you identify and write a Latin species name according to the Linnean system?
[a] Genus species, ex. Homo (genus) sapiens (species), Canis lupus, canis latrans, etc. Always capitalize the first and don’t capitalize the second. Italicize the name in a report or paper.
[q] What are the four plant phyla?
[a] Bryophyta (mosses, liverworts, hornworts), Filicinophyta (ferns), Coniferophyta (conifers), Angiospermophyta (flowering plants).
[q] What are the six animal phyla?
[a] Porifera (sponges), Cnidaria (hydras, jellyfish, corals, sea anemones), Platyhelminthes (flatworms, flukes, tapeworms), Mollusca (bivalves, gastropods, snails, squid, octopus, chitons), Annelida (marine bristleworms, oligochaetes, leeches), Arthropoda (insects, arachnids, crustaceans, myriapods).
[q] What are the five classes of vertebrates?
[a] Bony ray-finned fish, amphibians, reptiles, birds, and mammals.
[q] Describe the characteristics of the bony ray-finned fish.
[a] Bony-plate scales in the skin, one gill slit covered by an operculum, no limbs, fins supported by rays, external fertilization, remain in water, swim bladder contains gas, do not maintain constant body temp.
[q] Describe the characteristics of amphibians.
[a] Soft moist skin, simple lungs, four limbs when adult, external fertilization, larval stage in water and adult stage on land, eggs coated in protective jelly, do not maintain constant body temp.
[q] Describe the characteristics of reptiles.
[a] Impermeable skin covered with keratin scales, complex lungs, four limbs, internal fertilization, soft shelled eggs, teeth of all one type with no living parts, do not maintain constant body temp.
[q] Describe the characteristics of birds.
[a] Skin with feathers made of keratin, lungs with para-bronchial tubes, air sacs, two legs and two wings, internal fertilization, hard shelled eggs, beak but no teeth, maintain constant body temp.
[q] Describe the characteristics of mammals.
[a] Skin has follicles with hair made of keratin, lungs with alveoli, diaphragm, four legs/two wings & two arms, internal fertilization, live young, milk from mammary glands, teeth of different types with living core, maintain constant body temp.
[q] What are the goals of modern taxonomy?
[a] To identify, name, and classify new species.
[q] What are cladograms?
[a] Tree diagrams that show the most probable sequence of divergence in clades.
[q] What is a clade?
[a] A group of organisms that have evolved from a common ancestor, and include all living and extinct organisms.
[q] In which era did the first living organism appear?
[a] Precambrian.
[q] In which era did the first amphibian appear?
[a] Paleozoic.
[q] In which era did the age of mammals happen?
[a] Cenozoic.
[q] In which era did the photosynthesis and oxygen increase?
[a] Precambrian
[q] In which era did the first shelled animals appear?
[a] Paleozoic
[q] Which era was dominated by reptiles?
[a] Paleozoic
[q] In which era were the first land plants and animals?
[a] Paleozoic
[q] In which era did the first multicellular organism appear?
[a] Precambrian.
[q] What is the order of the four eras?
[a] Precambrian, Paleozoic, Mesozoic, Cenozoic.
[q] Give the chronological order of the following events: appearance of human ancestors, life first appears, earth is formed, multicellular animals appear.
[a] Earth is formed, life first appears, multicellular animals appear, appearance of human ancestors.
[q] A4.1.1—Evolution as change in the heritable characteristics of a population
This definition helps to distinguish Darwinian evolution from Lamarckism. Acquired changes that are not genetic in origin are not regarded as evolution.
[a]
The theory of evolution postulates that “life on earth evolved gradually beginning with one primitive species—perhaps a self-replicating molecule—that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection” (Jerry A. Coyne).
Evolution is the change in the heritable characteristics of a population across time.
[q] A4.1.2—Evidence for evolution from base sequences in DNA or RNA and amino acid sequences in proteins
Sequence data gives powerful evidence of common ancestry.
[a] Since the theory of evolution states that all species arose from one ancient common ancestor, DNA, RNA, and amino acid bases can be sequenced and analyzed in order to make comparisons between species.
The more similar the sequences of two species are, the more likely that they recently branched off from a common ancestor.
[q] A4.1.3—Evidence for evolution from selective breeding of domesticated animals and crop plants
Variation between different domesticated animal breeds and varieties of crop plant, and between them and the original wild species, shows how rapidly evolutionary changes can occur.
[a] Selective breeding is a form of artificial selection whereby humans intervene with the breeding of species to produce desired traits in offspring (i.e. breeding the fastest horse or crops with the most starch).
This shows how desired alleles increase in frequency in the gene pool of species over time, which is useful as it enables us to observe evolution at a faster pace than what normally occurs in nature.
[q] A4.1.4—Evidence for evolution from homologous structures
Include the example of pentadactyl limbs.
[a] Some organisms have the same structural anatomy of other species but they perform different functions (i.e. pentadactyl limbs function as arms for humans but fins for whales). These are homologous structures, and they show how one common ancestor evolved to adapt to new habitats, thus producing different functions using the same anatomical structures.
[q] NOS: The theory of evolution by natural selection predicts and explains a broad range of observations and is unlikely ever to be falsified. However, the nature of science makes it impossible to formally prove that it is true by correspondence. It is a pragmatic truth and is therefore referred to as a theory, despite all the supporting evidence.
[a] The evidence for evolution we have is but a fraction of what is available to us, since we have millions of undiscovered fossils and genomes waiting to be sequenced. This makes it impossible to explicitly say “we have all the possible evidence for evolution”, as it is beyond human capability to uncover all the evidence. However, it is still a very useful (pragmatic) theory, so it is treated like a truth in science as it is unlikely to ever be falsified.
[q] A4.1.5—Convergent evolution as the origin of analogous structures
Students should understand that analogous structures have the same function but different evolutionary origins. Students should know at least one example of analogous features.
[a] Divergent evolution (also called adaptive radiation) is when different species evolve from one common ancestor and have homologous structures.
Convergent evolution is when species from different ancestors evolve to have the same function despite being anatomically different (analogous structures). For example, insect and bird wings, while having the same function (flight), have evolved from different ancestors, and are thus classified as analogous structures.
[q] A4.1.6—Speciation by splitting of pre-existing species
Students should appreciate that this is the only way in which new species have appeared.
Students should also understand that speciation increases the total number of species on Earth, and extinction decreases it. Students should also understand that gradual evolutionary change in a species is not speciation.
[a] The theory of evolution does not predict that species will constantly be evolving, or how fast they’ll change when they do; that depends on the evolutionary pressures they experience.
Speciation is the process by which two populations of a single ancestor develop and evolve sufficient genetic differences that prevent interbreeding and the production of fertile offspring. Species don’t necessarily have to split, some just go extinct and others remain the same for years.
[q] A4.1.7—Roles of reproductive isolation and differential selection in speciation
Include geographical isolation as a means of achieving reproductive isolation. Use the separation of bonobos and common chimpanzees by the Congo River as a specific example of divergence due to differential selection.
[a] Geographical isolation is the phenomena by which two populations of the same species are separated geographically (i.e. separated by a mountain or river), preventing interbreeding. If their different habitats exert different selection pressures, differential selection will take place, which is a situation in which different traits are selected for in both populations.
For example, bonobos and chimpanzees are both primates that diverged from a common ancestor due to being separated by the Congo River, which acted as a geographical barrier given that both species are not proficient swimmers.
[q] A4.1.8—Differences and similarities between sympatric and allopatric speciation
Students should understand that reproductive isolation can be geographic, behavioural or temporal.
[a] Allopatric speciation = geographic isolation leading to speciation
• Sympatric speciation = reproductive isolation within the same geographic location leading to speciation
Two types of sympatric speciation:
• Temporal: different mating times of the year
• Behavioral: different courtship behavior
[q] A4.1.9—Adaptive radiation as a source of biodiversity
Adaptive radiation allows closely related species to coexist without competing, thereby increasing biodiversity in ecosystems where there are vacant niches.
[a] Adaptive radiation occurs when there are multiple vacant niches to be adapted to, thus one singular species can split into several species and coexist without competing, thereby increasing biodiversity in ecosystems. Increased biodiversity helps make ecosystems more resilient and less fragile to catastrophes like natural disasters and climate change, since there will be a sufficient number of species that are able to fill niches where other species failed to do so.
[q] A4.1.10—Barriers to hybridization and sterility of interspecific hybrids as mechanisms for of preventing the mixing of alleles between species
Courtship behaviour often prevents hybridization in animal species. A mule is an example of a sterile hybrid.
[a] Hybridization is when two different species crossbreed (i.e. a mule is produced when a horse and donkey crossbreed). Due to chromosomal differences in the two parents, the hybridized offspring, while containing useful traits from both parents (hybrid vigor), is sterile and unable to produce offspring.
Breeding to produce infertile offspring is a waste of energy and resources, so species have developed barriers to hybridization through distinct courtship behavior to ensure their mate is of the same species.
Thus, if mating occurs, the likelihood of producing a fertile offspring upon mating improves
[q] A4.1.11—Abrupt speciation in plants by hybridization and polyploidy
Use knotweed or smartweed (genus Persicaria) as an example because it contains many species that have been formed by these processes.
Note: When students are referring to organisms in an examination, either the common name or the scientific name is acceptable.
[a] Polyploidy results from non-disjunction during anaphase I (the homologous pairs do not separate), leading to an organism with a greater number of homologous chromosomes than the parent. In the case where the resultant diploid nucleus contains an even number of chromosomes, the species will usually be fertile, but if it is an odd number then the offspring may be able to survive, but it will be sterile. There are two types of polyploidies:
• Autopolyploidy occurs when the extra homologous chromosome(s) are derived from the same species (both parents belong to the same species).
• Allopolyploidy occurs when the extra homologous chromosome(s) are derived from different species (each parent is a different species).
Plants belonging to the genus Persicaria commonly hybridize due to hybrid vigor
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