Unit 8 Evolution

Intrasexular selection

Individuals compete directly with members of the same sex for mates (physical combat or ritual displays. Winning individual acquires mates

Endoderm

Internal sac formed by gastrulation becomes the digestive tract, lined by a cell layer called endoderm

Internal skeleton

Internal skeleton, under the thin skin of the animal

Metamorphosis

Larva undergoes a major change of body form called metamorphosis, becoming an adult capable of reproducing sexually.

What are the benefits of joint appendages

Legs that can bend to provide great stability and shock absorptions Flexibility and range of motion

What are other ways life could have arisen on earth

Life began in submerged volcanoes or deep sea hydrothermal vents, gaps in the earth's crust where hot water and minerals rush into deep oceans. These environments could have provided the initial chemical resources for life Another hypothesis proposes that meteorites were the first source of Earth's first organic molecules

Sexual dimorphism

Manifested in size difference but also forms of adorment (e.g manes on lions or colorful plumage on birds). Males are often the showier sex.

What is the fossil reccord

- Fossil Record: chronicle of evolution over millions of years of geologic time engraved in order in which fossils appear in rock strata. It is incomplete as many did not live in areas that favor fossilization or many were distorted by geological processes.

What is the biological species concept and what are the problems of the concept.

-Defines a species as a groups of populations whose members have the potential to interbreed in nature and produce fertile offspring -members of different species do not usually mate with each other -Reproductive isolation: Prevents genetic exchange (gene flow) and maintains a boundary between species. Hybrids are resulting offspring of clear distinct species that occasionally interbreed. Hybridization is most common in plants than animals and is a major factor in speciation, thus identifying species solely on basis of reproductive isolation is more complex than it may seem. Problems with concept: No way to determine whether organisms that are now known only through fossils were once able to interbreed Criteria is useless for organisms such as prokaryotes that reproduce asexually

What is genetic drift and how does it lead to natural selection? List the two ways.

-Genetic drift: chance events can cause allele frequencies to fluctuate unpredictably from one generation to the next - The smaller the population, the more impact genetic drift is likely to have (alleles can be lost completely in small populations) Bottleneck and Founder effect

How are fossils made and how was it used as evidence for evolution

-Imprints or remains of organisms that lived in the past -Documents differences between past and present organisms and the fact that many have become distinct. -Some fossils are the actual remnants of organisms, others are castes which form when a dead organism captured in sediment decomposes and leaves an empty mold that is later filled by minerals dissolved in water. The minerals harden, making a replica of the organisms. Fossils may also be imprints that remain after the organism decays. -Many are found in fine grained sedimentary rocks formed from sand or mud at bottom of aquatic habitats. New layers of sediment cover older ones and compress them into layers of rock called strata . Fossils in a particular stratum provide a glimpse of some of the organisms that lived in the the time the layer formed. The relative age of fossils can be determined by what strata they are found, thus the sequence in which fossils appear within layers of sedimentary rocks is a historical record of life on earth

Explain how mutations are involved in natural selection and which ones most impact it.

-New alleles originate by mutations (change in nucleotide sequence) - Ultimate source of genetic variation that serves as raw material of evolution. (in multicellular organisms, only mutations in gametes are passed on) - Change in single nucleotide can have significant effect on phenotype (e.g. sickle cell) - Most mutations are harmful, but on a rare occasion, mutated allele may improve the adaptation of an individual to its environment, enhancing reproductive success - Ones that delete, disrupt or rearrange many gene loci at a time are almost certainly harmful - Duplication of genes or in small pieces of DNA through errors in meiosis are important sources of genetic variation. -Repeated segments of DNA that persist over generations may accumulate in the duplicate copies without affecting the function of the original gene, eventually leading to new genes with novel functions (e.g. remote ancestors of mammals carried a single gene for detecting odors that has since been duplicated repeatedly, thus we have thousands of different olfactory receptor genes and can distinguish many different smells). Mutations that allow a specie to better adapt to it's environment will be able to better survive and reproduce, passing on those traits resulting in natural selection.

What are transitional forms

-Transitional forms: fossils that link two seemingly different types of organisms (ie. the transitional forms between terrestrial and aquatic mammals are predicted to have reduced hind limbs and pelvic bones)

List three key points about evolution by natural selection

1. Individuals do not evolve. It is the population that evolves over time as adaptive traits become more common, and other traits disappear. 2. Natural selection can amplify or diminish only heritable traits. An organism may become modified through its interactions with the environment during its lifetime, and those acquired characteristics may help it survive, but unless coded for in the genes of an organism's gametes, acquired characteristics cannot be passed onto offspring (e.g. champion body builder will not give birth to a muscle bound baby) 3. Evolution is not goal directed. It does not lead towards perfectly adapted organisms.

How do humans contribute to the problem of antibiotic resistance?

1. Livestock producers add antibiotics to animal feed as a growth promoter to prevent illnesses. These practice s select for bacteria that a resistant to standard antibiotics 2. Doctors may over prescribe 3. Patients misuse prescribed antibiotics by prematurely stopping medication because they feel better, allowing mutant bacteria that may be killed more slowly by drug to survive and multiply.

when did prokaryotes first arise (first evidence)

3.9-3.5 billion years ago

How long ago did earth form?

4.6 billion years ago

What influenced Darwin when formulating the idea of descent with modification

1. notice how characteristics of plants and animals allowed them to adapt and become well suited to each diverse environment. 2. geographic proximity was a better predictor of relationships among organisms than similarity of environments (animals found in grassland environment is more similar to animals found in the tropical rainforest nearby than grassland environments of another region) 3. Charles lyell "principle of Geography book 4 influenced by seeing the earth quake of chile, shift the elevation of the land

Cambrian Explosion

535-525 million years ago when animal diversification accelerated rapidly. Many animal body plans and new phyla appeared in fossils inevolutionary a short period of time. Cambrian animals had hard body parts such as shells and spikes (some fossils belonged to arthropods and chordata). Scientists believe increase in complex predator-prey relationships, and increase atmospheric oxygen led to rapid diversification.

How could chemical and physical could have produced simple cells

Abiotic synthesis of small organic molecules, such as amino acids and nitrogenous base Reasoned that present day conditions on earth does not allow spontaneous synthesis of organic compounds, but the atmosphere of early earth may have had a reducing (electron adding) atmosphere. The energy for this abiotic synthesis of organic compounds could have come from lightening and intense UV radiation. Joining of small molecules into polymers such as proteins and nucleic acids Usually, enzymes catalyze the joining of monomers to produce polymers in cells, however scientists have produced polymers in the laboratory by dripping dilute solutions of amino acids or RNA monomers onto hot sand, clay or rock. The heat vaporized the water and concentrates the monomers, some of which then spontaneously bond together in changed. Packaging of molecules into "protocells", droplets with membranes, maintained an internal chemistry different of their surroundings Key step in origin of life is the isolation of a collection of organic molecules within a membrane enclosed compartment. Laboratory experiments show that small membrane enclosed sacs or vesicles form when lipids are mixed with water. Researchers added a type of clay thought to be common on earth into the mixture and vesicles seemed to from at a faster rate. Organic molecules become concentrated on the surface of clay, thus more easily to interact. Smaller droplets form in abiotically created vesicles and are capable of growing and dividing (reproducing). Vesicles can can absorb clay particles to which RNA and other molecules attach. Origin of self replicating molecules that eventually made inheritance possible First genes are hypothesized to be short strands of self replicating RNA that can assemble spontaneously through nucleotide monomers. When RNA is added to solution containing RNA monomers, new RNA molecules complementary to parts of the starting RNA assemble

What is relative fitness and provide an example of a individual's relative fitness within the population

Adapted traits within a population can lead to greater relative fitness: the contribution an individual makes to the gene pool of the next generation relative to the contribution of other individuals. The fittest individuals in the context of evolution are those that produce the greatest number of viable, fertile offspring, and thus pass on most genes to the next generation. Example: In a varying population of moths, individuals whose wings are better camouflaged in the environment hiding them from predators are more likely to produce more offsprings, thus are considered fitter than those who do not camouflage. A man who wins the national bodybuilding association never has any children due to personal choice. His relative fitness is zero because he is not contributing to the gene pool of the next generation.

How does Migration influence natural selection

Allele frequencies in a population can change as a result of gene flow by which a population may gain or lose alleles when fertile individuals move into our out of a population, or when gametes (ie. pollen) are transferred between populations Tends to reduce differences between populations

What is the advantage of molecular biology

Allows biologists to analyze and assess relationships between groups of organisms that are so phylogenetically distant that structural similarities are absent. Allows us to reconstruct phylogenies among groups of present day prokaryotes and other microorganisms which we have no fossil record of at all.

Invertebrates

Animals lacking a backbone (makes up 96% of animals)

Vertebrates

Animals with backbones

Anterior Prosterior Dorsal Ventral

Anterior: distinct head Posterior: end; tail Dorsal: a back Ventral: Bottom or surface

Evolution of antibiotic resistant bacteria

Antibiotics are drugs that kill infectious microorganisms. Penicillin, one of the first antibiotics cured previously fatal diseases, however are virtually useless nowadays. This is because like pesticides selecting for resistant insects, antibiotics select for resistant bacteria.

Compare and contrast natural selection and artificial selection

Artificial: Humans select for an advantageous trait and then selectively breed organisms for it Natural: Environmental conditions present in an organism's area select for advantageous traits which were passed on to offspring when organism reproduces. Similarity: Both lead to changes in population over time.

Who are James Huntington and Charles lyell? How did their ideas influence Darwin?

Authors of (principles of Geology) Presented case for an ancient Earth sculpted over millions of years by gradual geologic processes that continue today (e.g. Earthquake) Led Darwin to realize that natural forces gradually changed Earth's Surface, and those forces still operate. Thus if earth moves and changes over time, animals can too. Darwin began to doubt that Earth and all its living organisms had been specifically created only a few thousands earlier leading him towards the hypothesis that present day species are descendants of ancient ancestors that they still resemble in some ways

What makes up the Domain

Bacteria, Archaea, Eukarya

Gastrovascular Cavity

Belly where food is digested (found in cnidarians and platyhelminthes)

Hydrostatic skeleton

Body cavity is filled with fluid giving it structure. The muscles contract to change the shape of the coelom, which then produces movement due to the pressure of fluid inside the fluid filled cavity

Radial symmetry

Body parts radiate from the center like the spokes of a bicycle wheel. Any imaginary slice through the central axis divides the animal into mirror images Animal has a top and bottom, but no right or left sides Produces two germ layers (diploblastic)

What is the bottleneck effect?

Catastrophes such as hurricanes, floods or fires may kill large numbers of individuals leaving a very small surviving population that is unlikely to have the same genetic makeup as the original population. -Certain alleles may be present at a higher frequency in the surviving population than in the original population. Others may be present at lower frequency or may not be present at all. -If population recovers its size, it may have low levels of genetic variation -Human activities such as overhunting, habitat destruction are bottlenecks

Explain a clade

Clade is a group of species that includes one ancestor species and all its descendents. (Monophyletic meaning "single tribe") For a clade, there should only be one cut

Phylogenetic species concept definition and cons

Defines a species as the smallest group of individuals that share a common ancestor and thus form one branch on the tree of life. Biologists trace the phylogenetic history of such species by comparing its characteristics such as morphology, DNA sequences or biochemical pathways, with those of other organisms. These sorts of analyses can distinguish groups that are generally similar yet different enough to be considered separate species Con: agreeing on amount of difference required to establish separate species remains a challenge.

Explain how to use a cladogram Shared ancestral character Shared derived character Outgroup Ingroup

Cladogram is used to illustrate relationships among organisms and evolutionary relationships for organisms with a common ancestor Shared ancestral character: a character shared by members of a particular clade that originated in an ancestor that is not a member of that clade; a trait that evolved in in the ancestor of the group and is present in all its descendents (though it may be lost or modified secondarily) Shared derived character: characteristic that a particular group of organisms have in common but not the ones before. An evolutionary novelty that is unique to a particular clade. Outgroup is a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the groups of species being studied. Ingroup: a species or group of species whose evolutionary relationship we seek to study. Parsimony: The adoption of the simplest explanation for observed phenomena. Scientists use it to construct phylogenetic trees that require the smallest number of evolutionary changes.

Morphological species concepts: advantages and disadvantages

Classification based mainly on physical traits such as shape, size and other features of morphology. This concept has been used to identify most of the 1.8 million species that have been named to date. Advantages: Can be applied to asexual organisms, and fossils, and does not require information on possible interbreeding Disadvantage: Approach relies on subjective criteria, and researchers may disagree on which features distinguish a specie.

Homeotic Genes

Cluster of master control genes that transform a zygote into an adult animal (genetic framework for complex bodies. Much of the diversity in body form among the animal phyla is associated with variations in where and when homeotic genes are expressed within developing embryos.Homeotic genes dictate which body parts develop and where on the body.

Polyp vs medusa

Cnidarians with cylindrical bodies with tentacles projecting from one end (mostly stationary) Free moving in water. Shaped like an umbrella with a fringe of tentacles

Cnidocytes/nematocyst

Cnidarians: unique stinging cells that function in defense and in capturing pray. Contains a fine thread coiled within capsule, and when discharged, stings or entangles prey.

Comparative embryology

Comparing early stages of development in different animal species reveals similarities not visible in adult organisms Closely related species have similar embryological development Structures in embryonic stage may have no function as an adult Provides evidence for common ancestry Similar genetic information of similar species direct the development of early embryonic stages making homologous structures Ex. At some point in development, all vertebrate embryos have a tail posterior to the anus, pharyngeal (throat) pouches that develop as gills in fish and parts of the ears and throat in humans

What is difference between coral animals and polyp cnidarians and how do they form coral reefs

Coral animals secrete a hard external skeleton Generations build on top of skeletons of previous ones

What is the order of hierarchical classifiaction of animals

Domain Kingdom Phylum Class Order Family Genus Specie

What are the four characteristics distinct to chordata

Dorsal hollow nerve cord Notochord: flexible, supportive longitudinal rod located between the digestive tract and nerve chord (later becomes a vertebrate column ) Pharyngeal slits: located in the pharnyx, region behind mouth (become the ear canal and throat in chordates, and gills in aquatic animals) Post-anal tail (tail posterior to the anus)

Ingestion

Eating food

Evolution of eyes

Evolution of eyes: The eye began as a patch of pigmented cells which then evolved into an eyecup, to simple pinhole eye, to eye with primitive lens, to complex camera lens type eye. This occurred because natural selection selected those which had the advantage of sight to escape predation or find food, thus evolving to become complex. However this is not goal directed which is why not all species have the complex camera lens type eye. The eye of the Limpet remains as the most basic patch of pigmented cell because there is no selection pressure acting upon it, thus making it already well adapted to the environment, not calling upon any more modifications. Complex structures can evolve by the gradual refinement of earlier versions of those structures, all of which served a useful function in each ancestor

Adaptive Radiation

Evolution of many diverse species from a common ancestor

Complete digestion + advantages

Extending tube from the mouth to anus. Food travels through a one way system and is processed as it moves along. Anterior regions churn and mix food with enzymes , while posterior regions absorb nutrients and dispose of wastes Advantages of having complete digestion Division of labor makes process more efficient Allows each part of digestive tract to be specialized for its particular function

Exoskeleton

External skeleton that protects the animal and provide points of attachment for muscles that move the appendages. Organisms with exoskeletons must go through a complex process of molting where it sheds its old exoskeleton, secreting a larger one in order to grow.

Deutrostomes

First opening that forms during gastrulation becomes the anus and the mouth forms a second opening

Protostromes

First opening that forms during gastrulation becomes the mouth

Mantal

Fold of tissue that drapes over the versial mass and secretes a calcium carbonate shell in molluscs such as clams or snails

Sexual selection

Form of natural selection in which individuals with certain traits are more likely than other organisms to obtain mates

Mesoderm

Forms the muscles and most internal organs

Compare and contrast how genetic drift, gene flow and mutation cause microevolution in contrast to natural selection causing microevolution

Genetic drift, gene flow and mutation cause microevolution. But only by chance these events result in improving a population's fit to its environment. In natural selection, on the other hand, only events that produce genetic variation (mutation + sexual reproduction) are random. The process of natural selection, in which better adapted individuals are more likely to survive and reproduce, is not random. Consequently, only natural selection leads to adaptive evolution - evolution that results in a better fit between organisms and their environment.

What did Lamark believe

Had the same belief that all organisms have changed over time and derived from a common ancestor, however Lamarck believed that traits are acquired through habit during lifetime and can be passed down to offspring. He says that a specie can change from simple to complex in a single lineage. He also says that animals are not able to become extinct, and that they have a tendency towards perfection (example: Bird ancestors desired to fly so they tried until wings developed.

Blastula

Hallow ball of cells during embryonic stage

Bilateral symmetry

Has mirror right and left sides. Animals with bilateral symmetry have brains, sense Organs and mouth usually located in the head at the anterior end. Distinct head, tail, back, bottom Produces a third tissue layer (triploblastic)

Ecological species concept

Identifies species in terms of their ecological niches, focusing on unique adaptations to particular roles in a biological community. ie. for example 2 species of fish may be similar in appearance but distinguishable based on what they eat or what dept of water they are usually found Disadvantages: Niches tend to be assumed and are difficult to define completely. Many taxa exploit overlapping resources, or can suddenly switch if a resource becomes scare.

Larva

Immature individual that looks different from the adult animal

Compare and contrast micro and macro evolution

Microevolution is change in gene pool of population from one generation to the next Macroevolution involves the pattern of evolutionary changes over large time spans and includes the origin of new groups and evolutionary novelties as well as mass extinctions

Coelom acoelomate psuedocoelomate Advantages of being a coelomate

Most animals with three tissue layers have a body cavity, or coelom, a fluid filled cavity lined by tissue formed from mesoderm in the embryo located in the space between the digestive tract and outer body wall, in which the internal organs are suspended. It provides cushioning and space for organs to develop. For organisms without blood, the coelom provides fluid fluid to distribute nutrients and oxygen, and ones without skeleton fill with fluid to give shape. Acoelomate: without a body cavity Pseudocelomate: animals have a pseudocoelom (literally "false cavity"), which is a fluid filled body cavity. Tissue derived from mesoderm only partly lines the fluid filled body cavity of these animals. Thus, although organs are held in place loosely, they are not as well organized as in a coelomate. Advantages of being a coelomate: Enables independent movement of the gut wall and body wall Provides space of the enlargement and development of internal organisms Helps protect the suspended organs from injury May act as a circulatory medium for transport of materials or a storage area of excess or waste material

Cladistics

Most widely used method in systematics Based on the concept that organisms share characters with their ancestors and differ from them

What constitutes as an animals

Multicellular Heterotrophic Eukaryotes No cell wall Held together by structural proteins (most abundant is collagen and by unique types intercellular junctions)

What two factors lead to genetic variation ands how do they drive natural selection

Mutations are the ultimate source of genetic variation and serves as the raw material for evolution. Sexual reproduction further increase genetic variation from three random components including crossing over, independent orientation and random fertilization. The variation in gametes leads to variation in organisms, contributing alleles into the gene pool. As a result, those with traits that are better suited to one environment may survive and pass on those traits, however if there is a shift in environment or conditions, others may have different traits that are more favorable in the new environment.

What are Ecdysozoans Eumetazoans

Nematods and Arthropods which have external skeletons that must be shed for the animal to grow. animals with true tissue

Water vascular system

Network of water filled canals that branch into extensions called tube feet (in echinoderm).

Sympatric speciation

New species arise within the same geographic area as its parent species. May occur when accidents during cell division result in extra sets of chromosomes. New species formed in this way are polyploid: meaning cells have more than two complete sets of chromosomes. Despite this, sympatric speciation is more likely to occur through habitat differentiation or sexual selection rather than polyploidy. Adaptations for exploiting different food sources may have evolved in different subgroups of original population. If those food sources were in different habitats, mating between populations would become rare, isolating the gene pools as each population becomes adapted to a different resources Speciation may occur by sexual selection in which females choose their mates. Mate choice can contribute to reproductively isolating populations, keeping the gene pools of newly forming species separate.

Heterotrophic

Obtains nutrients by ingestion

Ediacaran Period

Oldest fossils found during this period 575-550 million years ago. Discovered in Ediacara Hills of Australia and are impressions of soft bodied animals that varied in shape and ranged in length from 1cm-1m. (some belong to invertebrate groups that still exist today such as sponges and cnidarians

Open vs. closed circulatory system

Open: Blood is pumped through vessels that open into body cavities where organs are bathed directly in blood. Closed: Blood remains enclosed in vessels as it distributes nutrients and oxygen through blood

Divergent evolution

Organisms have common ancestor Changes in environment causes them to adapt May look/act differently but still related Homologous structures: features that often have different functions but are structurally similar because of common ancestry (ie. Forelimbs of humans, cats, whales and bats have the same skeletal elements however do not have the same function). Homology: similarity resulting from common ancestry (may look/act differently but still related)

Cephalization

Organisms with distinct heads, well developed brains, elaborate nervous system and complex thought process. They have a cluster of sensory organs in the head region with eyes, ears and nose.

Ectoderm

Outer cell layer that gives rise to the outer covering of the animal and in some phyla, the central nervous system

How does overproduction of offspring and limited resources drive natural selection

Overproduction of offspring leads to limited resources resulting in the struggle for existence, with only few offspring surviving in each generation. Individuals whose traits better enable them to obtain food, escape predators or tolerate physical conditions will survive and reproduce more successfully, passing these adaptive traits to their offspring.

How does natural selection work in insects resistance to pesticides

Pesticides control insects and prevent them from consuming crops or transmitting diseases. When a new type of pesticide is introduced, a relatively small amount of poison kills most of the insects, however the subsequent applications become less effective. This is because the few survivors of the first pesticide waves are ones that are genetically resistant, carrying an allele that somehow enables them to survive the chemical attack. Thus when most members of the population are killed, the resistant survivors are left behind to reproduce and pass on the pesticide resistant alleles to their offspring, increasing the proportion of pesticide resistant individuals in each generation.

Allopatric speciation

Populations separated by a geographic barrier are known as allopatric populations that block gene flow, preventing alleles from entering from other populations Geological processes can isolate populations (ie. mountain ranges emerge gradually and split populations that inhabit only low lands or large lakes subsiding into several smaller ones isolating fish populations). Size of geographic barrier to keep populations apart depends on ability of organisms to move. (bird, lions, coyotes can easily cross mountain ranges, windblown pollen of trees are not hindered by barriers , however animals such as small rodents may find a canyon or river wide enough to form a barrier within a population Speciation due to allopatric speciation occurs when the environment of an isolated population have varying food sources, pollinators or predators, and as a result of natural selection acting on preexisting variations, a population's traits may change in ways that also establish reproductive barriers

List an explain pre zygotic reproductive barriers

Prezygotic Mechanism: Prevent mating or fertilization Habitat Lack of opportunities to encounter each other Temporal Breeding at different times or seasons Behavioral Failure to send or receive appropriate signals Ie. blue footed booby performs an elaborate courtship dance while the masked booby performs a different courtship signal. Mechanical Physical incompatibility of reproductive parts ie. Heliconia pogonantha is pollinated by hummingbirds with long, curved bills while Heliconia latispatha is pollinated by hummingbirds with short straight bills Gametic Molecular incompatibility of eggs and sperm or pollen and stigma Ie. Sea urchins release their gametes into the water. Surface proteins prevent the gametes of different species from binding to one another

Exaptation

Process by which features acquire functions for which they were not originally adapted or selected for.(does not mean that a structure evolves in anticipation of future use. Natural selection cannot predict the future, it can only improve existing structure in context of current use). Example: Feathers on fossils of Tyrannosaurus rex were used for insulation while nowadays feathers on birds are used for flight. Or, penguins have wings but cannot fly, but they are modified as powerful oars that make them fast, strong, underwater swimmers.

What is speciation

Process by which one specie splits into two or more species

Postzygotic Barriers

Reduced hybrid viability Interaction of parental genes impairs the hybrid's development or survival Ie. some species of salamander can hybridize both their offspring does not develop fully or are frail and will not survive long to reproduce. Reduced hybrid fertility Hybrids are vigorous but cannot produce viable offspring Ie. hybrid offspring of a horse and donkey is a mule, which is robust but sterile. Hybrid breakdown Hybrids are viable and fertile, but their offspring are feeble or sterile Ie. rice hybrids are fertile but the next generation of plants are sterile

How are vestigial structures evidence of evolution.

Remnants of features that served important functions in the organism's ancestors (ex. Small pelvis and hind leg bones of whales are vestiges of their walking ancestors, or eye remnants buried under scales in blind species of cave fishes are a vestige of their sighted ancestors) May have retained genes that have lost their functions, even though homologous genes in related species are fully functional

Who is Thomas Malthus?

Said that more offspring than environment can supports leads to limited resources resulting in the struggle for survival and reproduction with only some offspring surviving in each generation. This led him to the realization that the essence of natural selection is in this unequal reproduction where individuals whose traits better enable them to obtain food or escape predation or tolerate physical conditions will be able to survive and reproduce more offspring successfully, passing these adaptive traits to their offspring.

Conditions of early earth

Scientific evidences indicates Earth formed about 4.6 billion years ago from a swirling cloud of dust that surrounded the young sun. As gases, dust and rocks collided and stuck together, larger bodies formed, and the gravity of the larger bodies in tur attracted more matter, forming the earth and other planets. 1. Immense heat generated by impact of meteorites and compaction of gravity 2. Atmosphere thick with water vapor along with various compounds released by volcanic eruptions including nitrogen and its oxides, carbon dioxide, methane, ammonia, hydrogen and hydrogen sulfide 3. Lightning, volcanic activity, and ultraviolet radiation was much more intense

Segmentation

Segmented body resembling a series of fused rings. Segmentation is the subdivision of the body along its length into a series of repeated parts. Advantages of a segmented body: Allows for greater flexibility and mobility evolved as an adaptation facilitating movement

Why is it so difficult to define a specie?

Specie comes from the Latin word for "kind" or "appearance" In many cases, the differences between two species are obvious, however in others, the differences are not so obvious. Two species may look very much the same however are different distinct species because of behaviors that differentiate them. Furthermore a singular group of species also may exhibit extreme variation in physical appearance however still belong to the same species. It is difficult to define a specie as it is difficult to come to terms with how many differences constitute to a new species and the degree on which features distinguish a specie.

Convergent evolution

Species from different evolutionary branches may come to resemble one another if they live in a similar environment and natural selection favors similar adaptations. Similarity due to convergent evolution rather than to descent from a common ancestor with the same trait = Analogy Same function but different structures and do not have a common ancestor (may look/act the same but are not related) Ie. Whales and Sharks look similar but are not related or butterfly wings and bird wings that both are for the function of flight but are not structurally similar or related)

Analogous structures

Species from different evolutionary branches may come to resemble one another if they live in a similar environment and natural selection favours similar adaptations. Similarity due to convergent evolution = Analogy Same function but different structures and do not have a common ancestor (may look/act the same but are not related)

Gastrula

Stage when one side of the blastula folds inwards

Molecular biology. How does it evidence for evolution.

The discipline that uses DNA and other molecular data to determine evolutionary relationships The study of molecular basis of genes and gene expression Just as hereditary background is recorded in the DNA you inherit from your parents, the evolution history of each species is documented in the DNA inherited from its ancestral species. If two species have homologous genes with sequences that match closely, biologist conclude that these sequences must have been inherited by a relatively recent common ancestor. The greater number of sequence differences between species, the more distant is there common ancestor. Provides evidence that all life forms use the same genetic language of DNA, RNA and the genetic code (codons-amino acids) making it likely that all species descended from common ancestors that used this code.

How is an organism's evolutionary history documented in its genome?

The longer two groups have been separated, the greater the divergence of their genes.

Describe natural selection as the mechanism that drives the process of evolution

Through Thomas Malthus's idea of overpopulation leading to struggle for survival and reproduction, Darwin deduced that the struggle for existence results with only some offspring surviving in each generation. He found that unequal reproduction is the essence of natural selection as Individuals whose traits better enable them to obtain food, escape predators, or tolerate physical conditions will survive and reproduce more successfully, passing these adaptive traits to their offspring. He concluded that over vast spans of time, many traits that adapt a population to its environment will accumulate. If the environment changes, or if an individual moves to another environment, natural selection will select for adaptations to these new conditions, sometimes producing changes that result in the origin of a completely new specie.

Urey and Miller

Through experiments, provided the first evidence that the molecules of life could have arisen spontaneously from inorganic precursors. He found that amino acids and other organic molecules could have formed under conditions that are thought to resemble those of early earth

True tissue

Tissue is an integrated group of cells with a common function, structure, or both. True tissues are collections of specialized cells, usually isolated from other tissues by membrane layers that perform specific functions.

explain the parts of the Binomial

Two part scientific name Genus: first part of name (a group of closely related species analogous to a person's surname in that it is shared by closest relatives) Specie: second part of the binomial (often called the specific epithet and is used to distinguish species within a genus. (analogous to a person's first name - unrelated people often have the same name thus the genus and specie must be used together. Ex. Sciurus carolinensis is a type of squirrel while Anolis carolinensis is a type of lizard

Founder effect. provide an example

When few individuals colonize an island or new habitat. -Smaller the group, the less likely the genetic makeup of the colonist will represent the gene pool of the larger population they left (ie. 15 ppl founded a colony on a group of small island. One of the colonists carried a recessive allele for blindness, thus after 100 years, the descendents who lived on the island had an a frequency of this allele that was 10x higher than in the British population from which the founders originated from.)

Microevolution

When the relative frequencies of alleles in a population change over a number of generations

Sessile

anchored in place

Choanocytes

cells with whip like flagelli powers the pump and sweeps water through the sponges body

Louis Pasteaur

confirmed that all life arises only by the reproduction of preexisting life Life not arise from non living matter today but the conditions of early earth, such an event could have hypothetically occurred.

Gene pool

consists of all copies of every type of allele at every locus in all members of the population

Visceral mass

contains the majority of internal organs inside the mollusc

Homologous structures

features that often have different functions but are structurally similar because of common ancestry (ie. Forelimbs of humans, cats, whales and bats have the same skeletal elements however do not have the same function). Homology: similarity resulting from common ancestry

Foot

functions for locomotion in molluscs

What are the three distinct body structures of arthropods What is cephalothorax

head, thorax and abdomen (cephalothorax is when head and thorax is partly fused

Descent with modifications

idea that present day species are descendents of ancient ancestors that spread into various habitats and over millions and millions of years accumulated diverse modifications or adaptations that fit them to specific ways of life in their environment.

How is comparative anatomology used for evidence of evolution?

it's the study of similarities and differences of anatomy of different species. Comparison of anatomical features to see similarity between structures that show species derived from a common ancestor.

What is the molecular clock and what are the pros/cons

method which estimates the time required for a given amount of evolutionary change (measures the number of changes in a genome over time) Molecular clocks are 'calibrated' against evolutionary events that are known from the fossil record. From these known events and rates of genomic change, the graph line can then be used to estimate the dates of other evolutionary episodes not documented in the fossil record. Pros: Molecular clocks have been used to date evolutionary timelines for organisms that do not have much of a footprint in the fossil record. They can also date evolutionary divergences that occurred a billion or more years ago, while as the fossil record only extends back 550 million years Cons: Accuracy of molecular clocks cannot be for sure as the rate of molecular change may vary at different times, in different genes and in different groups of organisms. The estimates of clocks assume that the rate of change is constant for all time, thus being uncertain.

Systematics

part of biology that deals with the classification of organisms based on shared characteristics and the determination of their evolutionary connectedness

Amoebocytes

produce supportive skeletal fibers composed of spongin (flexible protein) and mineral particles called spicules Spicules, spongin and collagen make up sponges

What is the difference between using rRNA and mtDNA? When would each be approriate for long term? short term?

rRNA changes relatively slowly so comparisons in DNA sequences in these genes are useful for investigating relationships between taxa that diverged hundreds of millions of years ago. mtDNA evolves rapiely and can be used to investigate recent evolutionary results.

Radula

rasping organ used to scrape up food

taxonomy taxa

system of naming and classifying species group

Cuticle

tough, nonliving material that covers the body of a nematode, preventing it from drying out. In parasitic species, the cuticle protects it from the host's digestive system