Vertebrate Zoology Midterm- Malone University

How is paedomorphosis important to evolutionary diversification of salamanders?

~Paedomorphosis has evolutionarily diversified salamanders through giving certain adults juvenile characteristics while other adults may not. ~When some species go through paedomorphosis and others do not, many evolutionary paths are created. ~When species keep many of the general features of their larval body form it could enhance the species' ability to survive.

List four characteristics of teleosts that contributed to their incredible evolutionary diversity.

1) changes in jaw suspension 2) increased fine control of gas reabsorption and secretion in the swim bladder (improves the control of buoyancy) 3) homocercal tail focuses most power to the tail (faster speed, precise steering, protection, and social communication) 4) cycloid scales decrease the weight and increase motility as well as increased feeding efficiency

Explain how each of the following contributes to Darwin's evolutionary theory: fossils, the geographic distribution of closely related animals, homology, and animal classification.

1. Fossils: support Darwin's evolutionary theory because they show that organisms have changed throughout time. 2. Geographic distribution of closely related animals: shows that animals with the same characteristics existed and evolved in different parts of the world, completely independently of one another. 3. Homology: supports the theory that all life evolved from a common ancestor 4. Animal classification: able to see the relationships between different organisms.

List three groups of adaptations that guided vertebrate evolution, and explain how each has contributed to the success of vertebrates.

1. Increased speed and mobility resulting from modification of the skeleton and muscles. 2. When vertebrates shifted from filter-feeding to active predation, new sensory organs, motor skills, and integrative controls became essential for the location and capture of larger prey. The endoskeleton allows for almost unlimited body size. 3. For the increased speed it developed a post-anal tail for movement. They have a brain/ganglion, and a notochord.

What problems have been identified with the biological species concept? How do other concepts of species attempt to overcome these problems? What problems do these other concepts entail?

1. it refers to contemporary populations and provides little guidance for tracing the temporal duration of a species lineage through its past history. 2. according to it, species do not exist in groups of organisms that reproduce only asexually. However, it is common taxonomic practice to describe species in all group of organisms. 3. systematists using this concept often disagree on the amount of reproductive divergence necessary for considering two populations separate species. ~Other concepts of species attempt to overcome these problems by providing guidance for retracing lineages through history (through the use of different phylogenetic data and methods), by including organisms that reproduce asexually, and making it clearer how two populations becomes two different species. ~A criticism of the evolutionary species concept is that it does not actually apply to a species, rather a population. The same is to be said about the cohesion species concept. ~The phylogenetic species concept is not able to be applied to all life forms yet because Detailed evolutionary histories have been described for relatively few groups of organisms.

Describe discoveries of living coelacanths. What is the evolutionary significance of the group to which they belong?

A coelacanth was found on a trawl off the coast of South Africa in 1938. More were found off the coast of the Comoro Islands. This is of evolutionary significance to the Sarcopterygii because this is the same place the ancestor of the tetrapods was found.

What is the relationship between a hypothesis and a theory?

A hypothesis is a possible explanation for observations. A theory is an explanation for what has been observed many times.

Hypothesis

A statement or proposition that can be tested by observation or experiment.

Describe the life cycle of freshwater eels.

Adult eels leave the coastal streams of Europe and North America, then swim to the Sargasso Sea (southeast of Bermuda) to spawn then die. Larvae then make their way back to Europe (1 year) and North America (3 years). After 6-15 years of growth, females go back to the ocean and join the males to go back to the Sargasso Sea to spawn.

Describe the ancestral amphibian life history, in which an aquatic larval stage precedes a metamorphosis that produces a terrestrial adult.

Aquatic eggs hatch into aquatic larva (lateral line and gills), metamorphosis, lose lateral line and gills, become terrestrial.

Why are arguments based on supernatural, or miraculous explanations, such as 'creation-science" or "intelligent design" not valid scientific hypotheses?

Arguments based on supernatural, or miraculous explanations are not valid scientific hypotheses because science is based on the observable world, as well as its physical and chemical laws. Supernatural and miraculous explanations are not observable or testable, and thus invalid as scientific hypotheses.

Describe the best hypotheses for explaining from key fossils how the ancestral tetrapod body plan first evolved in the Paleozoic Era.

Basically the ancestral body plan developed and became more tetrapodal over time from Eusthenopteron then, Tiktaalik, then Acanthostega, then Ichthyostega. ~Eusthenopteron- it had an upper arm bone (humerus) and two forearm bones (radius and ulna) as well as other bones that we homologize with the wrist bones of tetrapods. It could push itself through the bottom mud of pools with its fins but could not walk. ~Tiktaalik- is morphologically intermediate between lobe-finned fishes and tetrapods. It probably lived in shallow, oxygen-depleted streams or swamps, using its limps to help support the body as it placed its snout above the water to breathe. They may have come onto land. ~Acanthostega- had well-formed tetrapod limbs with clearly formed digits on both fore and hindlimbs, but they were not for walking on land. ~Ichthyostega- had a fully developed shoulder girdle, bulky limb bones, and well-developed muscles. It had a stronger backbone and associated muscle to support the body in the air, new muscles to elevate the head, strengthened shoulder, and hip girdles, a protective rib cage, a modified ear structure that detects airborne sounds, a foreshortened skill, and a lengthened snout.

After studying a population for a trait determined by a single pair of alleles, you find that this population departs from predictions of Hardy-Weinberg equilibrium in having higher than expected frequencies of homozygous genotypes and lower than expected frequencies of heterozygous genotypes. What possible reasons might explain its departure from equilibrium?

Departure from equilibrium may happen due to: selective removal of alleles that are damaging or harmful, inbreeding, changes in the population substructure, or genotyping error.

Explain why the system for naming species that originated with Linnaeus in binomial.

Each species has a Latinized name composed of two words written in italics.

Provide a brief description of fishes, citing characteristics that distinguish them from all other animals.

Fish are aquatic vertebrates with gills, appendages, if present, in the form of fins, and usually a skin with scales of dermal origin. Fish are distinct because they are the most ancient and most diverse of the clade vertebrata.

Experimental method

General procedure for testing hypotheses by predicting how a biological system will respond to a disturbance, making the disturbance under controlled conditions, and then comparing the observed results with the predicted ones.

If a taxonomist constructs a phylogenetic tree for a group of living species, the structure of the tree alone can be used to distinguish hypotheses of monophyly versus nonmonophyly of a particular subgroup. If monophyly is rejected for a particular subgroup, the structure of the tree alone cannot distinguish paraphyly from polyphyly. What additional information is needed to distinguish paraphyly from polyphyly?

If there is any common ancestor at all it is paraphyletic, if there is none at all then it is polyphyletc.

Offer a description of an adult tunicate that would identify it as a chordate yet distinguish it from any other chordate group.

In most species of tunicates, only the larvae have all five chordate hallmark characteristics. During adult metamorphosis, the notochord and post anal tail get reabsorbed, and the dorsal nerve chord is reduced to a single ganglion. The pharyngeal slits and endostyle are maintained.

What is the currently favored explanation for the evolution of vertebrate jaws?

It is currently favored that jaws arose from modifications of the first or second of the serially repeated cartilaginous gill arches. Once enlarged and equipped with extra muscles, the first pharyngeal arch easily could have been modified to serve as jaws.

Describe the early evolution of chordates and vertebrates.

It is thought that chordates evolved from a common ancestor of deuterostomes (echinoderms, hemi- chordates, and chordates). Most zoologists now consider the chordate ancestor to have been a small, free-swimming, filter-feeding creature. The earliest well-known vertebrates were the ostracoderms. Current vertebrates have evolved from them.

List in order, from most inclusive to least inclusive, the principal categories in Carolus Linnaeus's system of classification.

Kingdom, phylum, "class", order, family, genus, and species.

Briefly summarize Lamarck's hypothesis for evolution. What evidence rejects the hypothesis?

Lamarck believed that a physical change an organism goes through in its life can be passed down to their offspring. Also, as an individual organism transforms their characteristics through use and disuse of body parts, heredity responds to that, and evolution occurs. Evidence that rejects this hypothesis is genetic studies that show that traits obtained during an organism's life are not transmitted to offspring.

Describe some recurring criticisms of Darwin's theory of natural selection. How are these criticisms refuted?

Natural selection cannot create new species or structures but can modify old ones. This is refuted by looking at how certain structures were originally used and how they are used today. The function of these structures has changed over time, allowing for variation and speciation.

Why will our knowledge of the origin of life always be more tentative than our knowledge of the subsequent evolution of life's diversity?

Our knowledge of the origin of life is scientifically tentative because there is no scientific way to prove how life came to be, and people can bring religion into it. Our knowledge of the evolution of life's diversity is less tentative because we are able to look back at fossil records, create phylogenetic trees, and find common ancestors. We can research the evolution of life and discover answers, but it is not to easy to do that with the origin of life especially since none of us were there to observe it for ourselves, and there is no definitive way to find out how it happened.

Identify the random and nonrandom components of Darwin's theory of natural selection.

Random- variation Non-random- differential reproduction and survival

Discuss the functional morphology of sharks and rays, especially sensory and reproductive systems.

Sharks: the heterocercal tail provides thrust and some lift as it moves back and forth in the water. Placoid scales reduce the turbulence of water flowing over the body surface while swimming. Their lateral line system helps them locate prey from long distances by sensing low-frequency vibrations with mechanoreceptors. At close range, sharks use their vision as their main method of tracking prey. In the final stage of attack, the ampullae of Lorenzini guide them to their prey. All chondrichthyans have internal fertilization. Male sharks and rays have claspers to bring sperm to the female reproductive tract. Some sharks and all skates are oviparous, laying their eggs soon after fertilization. Rays and many sharks are viviparous, retaining developing young in the uterus and giving birth to fully formed young. They can exhibit placental viviparity in which the young are nourished via a placenta. All parental care is over once eggs are laid or young are born. ~Rays have dorsiventrally flattened bodies and enlarged pectoral fins which move in a wavelike manner to propel them. They have gill openings on the underside of their head, and spiracles for passage of water. They have teeth adapted for crushing prey. ~Stingrays have a slender, whip-like tail armed with one or more saw-toothed spines to defend themselves from predators. ~Electric rays have powerful electrical organs on both sides of their head with enough voltage to stun prey. 1. Three semicircular canals 2. good sense of smell 3. lateral line (detecting changes in water pressure) 4. ampullae of Lorenzini (electroreceptors) 5. Single circulation heart 6. 5-7 gills 7. oil-filled liver for buoyancy 8. Oviparous, oviviparous, or viviparous reproduction 9. placoid scales 10. Heterocercal tail

Explain why genetic drift is more powerful in small populations.

Smaller populations are typically less diverse than larger ones, so there are not as many alleles available to help balance random fluctuations in allele frequencies.

Describe how fish swim, maintain buoyancy, osmoregulate, and obtain oxygen.

Swim- Myomeres (short w-shaped muscle) expands and contracts allowing them to use their muscle to thrust and create a lateral force Maintain buoyancy- They have a swim bladder that inflates and deflates based on if the fish wants to go up or down. Osmoregulate- Freshwater fish osmoregulate through hyperosmotic regulation. Marine fish osmoregulate through hypoosmotic regulators. Obtain oxygen- They obtain oxygen by obtaining water through their mouth, having the water pump over their gills, and out their gill slits.

Control

That part of a scientific experiment to which the experimental variable is not applied, but similar to the experimental group in all other respects.

Hypothetico-deductive method

The central procedure of scientific inquiry in which a postulate is advanced to explain a natural phenomenon and then subjected to observational or experimental testing that potentially could reject the postulate.

What is meant by "countercurrent flow" as it applies to fish gills?

The direction of the water flow is opposite to the direction of blood flow. This is the best arrangement for extracting the greatest possible amount of oxygen from the water.

what are the essential characteristics of science? Describe how evolutionary studies fit these characteristics.

The essential characteristics of science are: 1) it is guided by natural law 2) it must be explanatory by reference to natural law 3) its conjectures are testable against the empirical world 4) its conclusions are tentative and not necessarily the final word 5) it is falsifiable. Evolutionary studies fit these characteristics because at the core of evolution is natural law. Also, evolutionary studies are considered hypotheses, and thus acceptable, revisable, and falsifiable until proven correct.

What function does the lateral line system serve? Where are receptors located?

The lateral line system is used to help locate prey from long distances by using low frequency vibrations with mechanoceptors in the lateral line. The lateral line is located along the sides of the body and over the head.

Explain why the population, not the organism, is the unit of evolution.

The population is the unit of evolution because it is capable of evolution, individual organisms are not because they hold the same genes throughout their lifetime. As a population evolves, the ratios of genetic types is changing rather than each individual is changing.

A common but mistaken notion is that because some alleles are genetically dominant and others are recessive, dominants eventually replace all recessives in a population. How does the Hardy-Weinberg equilibrium refute this notion?

The recessive allele may not be expressed, but it is still present and occurs more often than the dominant allele. Recessive alleles are not eliminated from the population through natural selection, but almost all copies of those alleles are found in heterozygous genotypes, which are phenotypically normal. Since the recessive alleles are phenotypically normal, there is no reason for dominant to replace all recessives.

How do adult Pacific salmon find their way back to their parent stream to spawn?

They have an instinct called the Homing instinct. They are guided upstream by the distinctive odor of their parent stream. They imprint on odors of other streams they pass while migrating down river and they use the odors in reverse sequence as a map during the upriver migration as returning adults.

What morphological characteristics distinguish lobe-finned fishes?

They have fleshy, lobed, muscular pelvic and pectoral fins that they use to "walk" and swim underwater across substrate.

Explain how lungfishes are adapted to survive out of water.

They survive the dry season by burrowing into mud and secreting a copious slime, which hardens into a cocoon that the fish remains dormant in until it rains.

In 1928, Walter Garstang hypothesized that tunicates resemble the ancestral stock of the vertebrates. Explain this hypothesis and evaluate its validity based on recent phylogenetic and developmental data.

This hypothesis suggested that the chordates were derived by retaining the larval form of sessile tunicate-like animals into adulthood. Garstang then suggested that the tadpole larva failed to metamorphose into an adult tunicate, instead developing gonads and reproducing in the larval stage. With continued evolution, a new group of free-swimming animals appeared (the ancestors of cephalochordates and vertebrates). Garstang called this process paedomorphosis. He suggested that evolution may occur in larval stages of animals. In this case it led to the development of vertebrates.

Explain why it is necessary to know the life history of a tunicate in order to understand why tunicates are chordates.

Through learning about the life history of a tunicate, we can understand more about the origin of vertebrates and improve our knowledge. It is important because as adults, tunicates are highly specialized chordates. In most species only the larval form bears all the chordate hallmarks.

Briefly describe characteristics of vertebrates that distinguish them from nonvertebrate chordates.

Vertebrate chordates have vertebrae/backbone, whereas nonvertebrate chordates do not have vertebrae/backbone. Vertebrate chordates have a notochord as adults, whereas nonvertebrate chordates have a notochord at some point in their development, but no backbone/vertebra.

Identify animal groups that are chordates and those groups that are also considered vertebrates.

Vertebrates- mammals, fish, reptiles. Invertebrates- tunicates, cephalochordates.

How do Monophyletic, Paraphyletic, and Polyphyletic taxa differ? How do these differences affect the validity of such taxa for both evolutionary and cladistic taxonomies?

~A paraphyletic group is a taxon that consists of the most recent common ancestor and some of its descendants. ~A monophyletic group is a taxon that consists of the most recent common ancestor of all those organisms and all the descendants of that most recent common ancestor. ~A polyphyletic group is a taxon that consists of unrelated organisms who are from a different recent common ancestor.

Describe the life cycle of sea lampreys, Petromyzon marinus, and the history of their invasion of the great lakes.

~All lampreys ascend freshwater streams to spawn in the winter or spring in shallow, gravel-filled areas. ~In the stream, the female releases her eggs into the nest made by the male and the male fertilizes them. Adults die soon after spawning. ~Ammocoetes are the filter-feeding larval stage of lampreys. They hatch around two weeks after fertilization. ~Larvae live 3 to 7 years, filter feed on small organisms and fine organic matter, and then rapidly metamorphosize into adults. ~Parasitic lampreys migrate to the sea or stay in fresh water and attach themselves to fish and eat them. Freshwater adults live 1-2 years before spawning and then die. Marine adults live 2 to 3 years. ~Nonparasitic lampreys do not feed after becoming adults, and their digestive tract degenerates. They will shortly spawn then die. ~Lamprey invasion of the Great Lakes started because of deepened canals to the Great Lakes (caused by man). It is being kept under control mainly with larvicides.

Describe the different modes of respiration used by amphibians. What paradox do the amphiumas and terrestrial plethodontids present regarding the association of lungs with life on land?

~Amphibians use 3 different respiratory surfaces for gas exchange in the air: skin, mouth, and lungs. ~At various stages in their life history, salamanders may have external gills, lungs, both, or neither of these structures. ~Cutaneous respiration: using extensive vascular nets in the skin for respiratory exchange of oxygen and carbon dioxide with the external environment. ~Lungs: are present from birth in the salamanders that have them, and they become the primary means of respiration following metamorphosis ~Amphiumas have a completely aquatic life history, but they lose their gills before adulthood and then breathe primarily by lungs, raising their nostrils above the water surface to get air. ~Plethodontids are the most completely terrestrial group of salamanders, and they do not have lungs.

Compare and contrast hagfishes and lampreys.

~Both are Agnathans. They both lack jaws, internal ossification, scales, and paired fins. ~They both have pore-like gill openings and an eel-like body form. ~Hagfish have four pairs of tentacles around the mouth; buccal funnel absent; 1-16 pairs of gill openings; slime glands present; vertebrae vestigial; about 78 species. ~Lampreys have a buccal funnel with keratinized teeth, but no barbels, nasal sac not connected to pharynx; vertebrae present only as neural arches; 7 pairs of external gill openings; 41 species, freshwater and anadromous.

Describe the shared and distinctive characteristics of caecilians and salamanders.

~Caecilians- body elongate; limbs and limb girdle absent; mesodermal scales present in skin of some; tail short or absent; 95-285 vertebrae; pantropical, 10 families, 32 genera, approximately 200 species. ~Salamanders- body with head, trunk, and tail; no scales; usually two pairs of equal limbs; 10-60 vertebrae; predominately Holarctic; 9 living families, 70 genera, approximately 710 species.

What is the difference between a cladogram and a phylogenetic tree? Given a cladogram for a group of species, what additional information is needed to obtain a phylogenetic tree?

~Cladograms give a hypothetical idea of the evolutionary history of the organisms. Cladograms only show the relationships between organisms in terms of a common ancestor. ~Phylogenetic trees give an actual representation of the evolutionary history of the organisms. Phylogenetic trees show the relationship between different organisms while keeping in mind the evolutionary time and the amount of change with time.

Explain how Darwin's Journey on the Beagle and his studying of pigeon breeding affected his thinking.

~Darwin described what he saw one Galapagos islands as the "origin of all my views". This trip truly validated the way he was thinking, and it also brought him new ideas as well. For example, the voyage produced the start of his theory of evolution and natural selection. ~By crossing birds with different characteristics, he could generate different offspring. He came to the conclusion that similar but different species were products of evolutionary change.

Explain the changes to Darwin's theory contributed by subsequent work in genetics and paleontology.

~Darwin's theory was altered by integrating and identifying a mechanism for inheritance. The genetic basis of Neo-Darwinism is the chromosomal theory of inheritance. Studies of microevolution and macroevolution have also been integrated into the theory and have helped to expand it in many different ways. ~Paleontologists work with fossils which helps to explain the process of evolution. We have learned that natural selection, species selection, and catastrophic species selection interact and produce macroevolutionary trends that are visible within the fossil record. As a result, we are able to conclude that life on earth was once different than what it is like now.

How do cladists and evolutionary taxonomists differ in their classifications of humans and apes? Contrast their respective interpretations of the statement that humans evolved from apes, which evolved from monkeys.

~Evolutionary taxonomy groups the genera Gorilla, pan, and Pongo into the paraphyletic family Pongidae because they share the same adaptive zone or grade of organization. Humans are placed in a separate family of Hominidae because they represent a different grade of organization. ~Cladistic taxonomy eliminates the paraphyletic family Pongidae and groups Pongo, Gorilla, Pan, and Homo into a single monophyletic family, Hominidae. ~Evolutionary taxonomists interpret the statement to mean that apes and humans are different adaptive zones or grades of organization; humans evolved from apes states that bipedal organisms of large brain capacity evolved from arboreal, quadrupedal organisms of smaller brain capacity. ~To a cladist the statement that humans evolved from an arbitrary grouping of species that lack the distinctive characters of a human contains no useful information.

Reproduction in marine pelagic fishes and in benthic freshwater fishes is distinctively different. How and why do they differ?

~Freshwater fish normally produce nonbuoyant eggs. Some provide no parental care and scatter the eggs among weeds or sediment. Freshwater fish that do provide egg care produce fewer, larger eggs that have a higher chance of survival. They do this because they live on the bottom of the sea. ~Marine fish produce large, yolky nonbuoyant and adhesive eggs. Some bury their eggs, some attach them to vegetation, some deposit them in nests, others incubate them in their mouths, and many guard their eggs. They do this because they live in the upper layers of the sea.

Compare the osmotic problem and the mechanism of osmotic regulation in freshwater and marine bony fishes.

~Freshwater: water enters their bodies osmotically and salt is lost by diffusion outwards because freshwater has a salt concentration much lower than that of the blood of freshwater fish. They are hyperosmotic regulators that pump out excess water through their opisthonephric kidneys. Salt in their diet helps replace the salt lost through diffusion. ~Marine: they are hypoosmotic regulators, so they have a much lower blood-salt concentration than the seawater. As they lose water, they gain salt. To prevent drying out, they drink seawater and excess salt is secreted out by special salt-secretory cells in the gills. Excess salt is disposed of through feces or excreted by tubular kidney secretion.

Describe feeding behavior in hagfishes and lampreys. How do they differ?

~Hagfishes are entirely marine animals, and most are scavengers. Hagfish enter dead or dying animals through a bodily opening or by digging their way in by using the keratinized plates on their tongue. Hagfish are almost blind, so they locate food by with their advanced sense of smell and touch. ~Lampreys are usually filter feeders as larvae and parasites as adults. As adults, lampreys attach themselves to fishes, whales, and dolphins. They dig away at their skin with conodonts. The lamprey then intakes the tissues and body fluids of its host.

Contrast, using examples, two kinds of migratory fishes: anadromous and catadromous.

~Homing salmon are anadromous, they spend their adult lives at sea but return to freshwater streams to spawn. Atlantic salmon can make multiple upstream spawning trips. The Pacific salmon make a single spawning trip and then they die. ~Freshwater eels are catadromous they spend most of their lives in freshwater but migrate to the sea to spawn. Adult eels leave the coastal streams of Europe and North America, then swim to the Sargasso Sea (southeast of Bermuda) to spawn then die.

What key idea, contained in Malthus's essay on populations, helped Darwin formulate his theory of natural selection?

~In Malthus's book he stated that animal and plant populations, including human populations, have the reproductive capacity to increase beyond the capacity of their environment to support them. ~This inspired Darwin greatly because he realized that a process of natural selection was driven by a struggle to exist due to overpopulation. This could be a strong driver for the evolution of species.

Explain the use of a cladistic classification for vertebrates changes the major important regroupings of traditional vertebrate taxa. Why are agnatha and reptilia, as traditionally recognized, inconsistent with cladistic principles?

~In cladistic usage, some of the traditional taxa are no longer recognized or have been redefined. These taxa do not satisfy the cladistic requirement that only monophyletic groups are taxonomically valid. ~The Protochordates and Vertebrata are separated. ~Vertebrates may be subdivided into groups based on shared characteristics. ~Agnatha and reptiles are not inconsistent with cladistic principles because they are paraphyletic groups.

What is the phylogenetic placement of Haikouella, and what evidence supports its placement there?

~It has been hypothesized to be the sister taxon of vertebrates (craniates). ~It has been placed this way because it has several characteristics that define it as a chordate: a notochord, pharynx, and dorsal nerve cord. Like vertebrates, its fossils have pharyngeal muscles and an enlarged brain.

Is it easier for selection to remove a deleterious recessive allele from a randomly mating population or from a highly inbred population? Why?

~It is easier to remove it from a randomly mating population because natural selection keeps recessive lethal alleles rare in the population because individuals homozygous for such alleles never reproduce (they usually die off young). ~With inbreeding it is harder because strong inbreeding usually increases the chances that rare recessive alleles become homozygous and thus are expressed.

Give the literal meaning of the name Gymnophiona. What animals are in this amphibian order? Describe their appearance and habitats.

~It means "naked" and "of a snake", so it means "naked snake". ~This order is comprised of over 200 species of elongate, limbless, burrowing creatures. ~They have a long slender, body; many vertebrae; long ribs; no limbs; a terminal anus; some have small dermal scales in the skin; small eyes, most species are blind. ~They can be found in tropical forests of South America, Africa, India, and Southeast Asia.

What does the theory of punctuated equilibrium state about the occurrence and importance of speciation throughout geological time?

~It says that phenotypic evolution is focused in rather brief events of branching speciation, followed up by much longer intervals of morphological evolutionary stasis. ~A small fraction of the total evolutionary history of a group accounts for most of the morphological evolutionary change that occurs.

Explain the similarities and differences between the Linnean system of classification, Simpson's evolutionary taxonomy, and phylogenetic systematics following Hennig.

~Linnean System of classification: Phonetic taxonomy- grouped by similarities, polyphyletic. ~Simpsons evolutionary taxonomy: Evolutionary taxonomy- Single origin, some unique adaptive features, grade (a group of taxa that share a unique adaptive zone), mono or paraphyletic. ~Phylogenetic Systematics: Cladistics, Monophyletic only.

What evidence suggests that hagfishes and lampreys form a monophyletic group?

~Many phylogenetic analyses of molecular data consistently support the Cyclostomata grouping of hagfishes and lampreys, suggesting that the apparently "simple" morphology of hagfishes represents degeneracy rather than an ancestral vertebrate condition. ~Also, vertebrae appear as rudimentary structures in some hagfish embryos which suggests that vertebrae were present in the common ancestor of all living vertebrates.

Contrast microevolution and macroevolution.

~Microevolution is a change in the gene pool of a population across generations. ~Macroevolution is evolutionary change on a grand scale, encompassing the origin of novel designs, evolutionary trends, adaptive radiation, phylogenetic relationships of species, and mass extinction.

Give precise definitions of monophyly, paraphyly, and polyphyly as alternative ways that the members of a taxon can map onto its phylogenetic tree.

~Monophyly is a condition occurring when a taxon or other group of organisms contains the most recent common ancestor of the group and all of its descendants. ~Paraphyly is the condition that a taxon or other group of organisms contains the most recent common ancestor of all members of the group but excludes some descendants of that ancestor; shows convexity. ~Polyphyly is the condition that a taxon or other group of organisms does not contain the most recent common ancestor of all members of the group, implying that it has multiple evolutionary origins; such groups are not valid as formal taxa and are recognized as such only through error.

List or briefly describe five characteristics of chordates.

~Notochord- a flexible rod extending the length of the body. ~Dorsal tubular nerve cord- anterior end becomes enlarged to form the brain in vertebrates. ~Pharyngeal pouches/slits- openings that lead from the pharyngeal cavity to the outside. ~Postanal tail- provides motility that larval tunicates and amphioxus need for their free-swimming experience. ~Endostyle/thyroid gland- secretes mucus that traps small food particles brought into the pharyngeal cavity

Name five characteristics shared by all chordates, and explain the function of each.

~Notochord- elongated cartilaginous, cellular cord, enclosed in a sheath, that forms the primitive axial skeleton of chordate embryos, adult cephalochordates, and jawless vertebrates. ~Dorsal tubular nerve cord- anterior end becomes enlarged to form the brain in vertebrates. ~Pharyngeal pouches/slits- openings that lead from the pharyngeal cavity to the outside. ~Post anal tail- provides motility that larval tunicates and amphioxus need for their free-swimming experience. ~Endostyle/thyroid gland- secretes mucus that traps small food particles brought into the pharyngeal cavity.

Describe the observations and inferences that compose Darwin's theory of natural selection.

~Observation 1- organisms have great potential fertility, which permits exponential growth of populations. ~Observation 2- natural populations normally do not increase exponentially but remain fairly constant in size. ~Observation 3- natural resources are limited. ~Observation 4- variation occurs among organisms within populations. ~Observation 5- variation is heritable. ~Inference 1- a struggle for existence occurs among organisms. ~Inference 2: varying organisms show differential survival and reproduction, favoring advantageous traits. ~Inference 3: natural selection, acting over many generations, gradually produces new adaptations and new species.

Distinguish between ostracoderms and placoderms. What important evolutionary adaptions first appeared in each group? What are conodonts?

~Ostracoderms are a paraphyletic group of extinct, jawless fishes with dermal armor known from the late Cambrian to Devonian periods. Most lacked paired fins. ~Dermal armor is the important evolutionary adaptation in Ostracoderms. ~Placoderms are a group of heavily armored jawed fishes of the Lower Devonian to Lower Carboniferous periods. ~Jaws are the important evolutionary adaptation in Placoderms. ~Conodonts are a toothlike element from a Paleozoic animal now considered an early marine chordate.

Explain how Darwin's theories of perpetual change, common descent, and multiplication of species are supported by data and why continuing controversies about the roles of gradualism and natural selection do not challenge these first three theories.

~Perpetual change is documented by the fossil record, which refutes any claims for a recent origin of all living forms. It has withstood repeated testing and is supported by a lot of observations, so it is now considered fact. ~Common descent is supported by the fact that we have been able to reconstruct a history of life all the way back to a primordial ancestor of all life on earth. ~Multiplication of species is supported by allopatric speciation, specifically when the Isthmus of Panama fragmented an ancestral population if Eucidaris sea Urchins into separate Caribbean and pacific isolates, leading to the formation of a new pair of species. ~Gradualism and natural selection do not challenge these first three theories because they are generally accepted as having universal application throughout the living world. Gradualism and natural selection do not necessarily explain as much of animal evolution as Darwin may have thought.

Describe the five major conjectures of Darwin's evolutionary theory: perpetual change, common descent, multiplication of species, gradualism, and natural selection.

~Perpetual change states that the world is always changing. ~Common descent states that all life came from a common ancestor. ~Multiplication of species states that new species are produced by the evolutionary process through splitting and transforming older species. ~Gradualism states that animals change slowly over time. ~Natural selection states that those who are the fittest will survive.

What characteristics are shared by the deuterostome phyla that indicate a monophyletic group of interrelated animals?

~Radial cleavage ~An anus derived from the first embryonic opening (blastopore) and a mouth derived from an opening of secondary origin ~A coelom primitively formed by fusion of enterocoelous pouches

Contrast the two major clades containing bony fishes.

~Sarcopterygii- fishlike members with skeleton ossified; gills covered by bony operculum; paired fins with sturdy internal skeleton and musculature within appendage; diphycercal tail; usually with lungs; atrium and ventricle at least partly divided; teeth with enamel covering. ~Actinopterygii- skeleton ossified; gills covered by bony operculum; paired fins supported primarily by dermal rays; appendicular musculature within the body; swim bladder mainly for buoyancy, if present; atrium and ventricle not divided; teeth with enameloid covering.

Both sea squirts (urochordates) and lancelets (cephalochordates) are filter feeding organisms. Describe the filter feeding apparatus of a sea squirt and explain in what ways its mode of feeding is similar to, and different from, that of amphioxus.

~Sea squirts filter feed by using a mucus sheath secreted by the endostyle on the ventral side of the pharynx. Cilia on the gill bars of the pharynx stretch the mucous into a sheet that spreads across the the pharynx. Food particles brought in the incurrent siphon are captured in the mucus sheet. The mucus sheet is worked into a rope and carried by cilia into the esophagus and stomach. ~It is similar to amphioxus because they both use a mucous sheet and cilia. ~It is different because the food particles are separated from the mucous and passed to the hepatic cecum in amphioxus, where they are phagocytized and digested intracellularly.

Sharks and bony fishes approach or achieve neutral buoyancy in different ways. Describe the methods evolved in each group. Why must a teleost adjust the gas volume in its swim bladder when it swims upward or downward? How is gas volume adjusted?

~Sharks do not have a swim bladder, so to keep from sinking, they must always keep moving forward in the water. The shark's tail shape provides lift as it goes through the water. ~Fish maintain desired buoyancy by adjusting the volume of gas in their swim bladder. They are able to maintain almost any depth with almost no muscular effort.

Explain how bony fishes differ from sharks and rays in the following systems or features: skeleton, scales, buoyancy, and respiration.

~Skeleton- sharks/rays have cartilaginous bones rather than the calcified bones bony fish have. ~Scales- sharks/rays have indents in their skin, whereas bony fish have flat scales that grow along with the fish. ~Buoyancy- sharks/rays use their cartilaginous skeletons to float and maintain buoyancy, but bony fish have a swim bladder that allows them to control where they are in the water/buoyancy. ~Respiration- sharks/rays have a four chambered heart, and so do bony fish, but the fourth chamber is made of elastic fibers and smooth muscles.

Describe how fundamental changes to the ancestral, metamorphic life history have occurred in some groups of frogs and salamanders.

~Some salamanders do not do complete metamorphosis and keep a larval, aquatic morphology through their life. ~Some caecilians, frogs, and salamanders live entirely on land and do not have an aquatic larval phase whatsoever. ~Some amphibians that undergo metamorphosis remain in water as adults rather that moving onto land.

How does observation of "sports" in animal breeding challenge Darwin's theory of gradualism? Why did Darwin consider such mutations to have little evolutionary importance?

~Sports challenge Darwin's theory because they change the phenotype largely in a single mutational step, which contradicts Darwin's theory that phenotypic changes are small and incremental over long periods of time. ~Darwin considered sports to be unimportant because they always have negative impacts that would prevent affected organisms from surviving in natural populations.

Evolution of the tetrapod limb was one of the most important advances in vertebrate history. Describe the inferred sequence of its evolution.

~Tetrapod limbs evolved in an ancestral aquatic habitat during the Devonian period before their transition onto land. ~The bony elements of the paired fins of lobe-finned fishes show they are homologous with amphibian limbs. ~Through the fossil record, we can see that many extinct species of lobed-finned fish show evolutionary developments of tetrapods in water that later transitioned to living on land.

Compare the swimming movements of eels with those of trout, and explain why the latter are more efficient for rapid locomotion.

~The eel has a serpentine swimming movement. The contractions move the full length of the body. The amplitude of the undulation increases as it moves to the end of the eel. ~The trout is less flexible and has fewer body undulations. The fish is more so built for speed than the eel for a few reasons. The eel is somewhat efficient at low speeds, but when they try to swim fast, there is too much frictional drag from the side-to-side movement. ~With the trout, most of the energy goes to the caudal fin. This results in greater speed.

Describe the breeding behavior of a typical woodland salamander.

~The eggs are fertilized internally. ~The female recovers in her cloaca a packet of sperm deposited by a male on a leaf or stick. ~The female then stores the sperm in her body and uses it to fertilize her eggs before laying them. ~The female deposits her eggs in small clusters under logs or in excavations in soft moist earth, and in many species the adults guard their eggs. ~The baby salamanders have direct development, they hatch as small versions of adults.

Proximate (immediate) cause

~The factors that underlie the functioning of a biological system at a particular place and time, including those responsible for metabolic, physiological, and behavioral functions at the molecular, cellular, organismal, and population levels (aka immediate cause). ~How something happens.

What major evolutionary lesson is illustrated by Darwin's finches on the Galapagos islands?

~The major evolutionary lesson that is illustrated by Darwin's finches on the Galapagos Islands is adaptive radiation on an oceanic archipelago. ~This is an example of natural selection and speciation. The finches on the Galapagos Islands are also an example of disruptive selection. ~The finches help us to better understand adaptive radiation, evolutionary divergence, multiplication of species, and how they work. Though they are greatly adaptive and diverse, they do not clearly form distinct species lineages because they share genetic compatibility and gene exchange.

How do modern evolutionists view the relationship between ontogeny and phylogeny?

~The modern evolutionist's view is that early developmental features were shared among the different animal groups that were present at the time. ~This helps explain why there are embryological similarities seen in organisms that end up looking very different when they are adults.

Explain that science consists in testing, possibly rejecting, and improving our simplest and best explanations using data, not in proving the correctness of a conjecture.

~The pursuit of scientific knowledge is guided by physical and chemical laws that govern the state of existence. ~Scientific knowledge must explain observations by reference to natural law without intervention of any supernatural being or force. ~We must record observations that directly or indirectly test hypotheses about nature. ~We must discard or modify and conclusion if further observations contradict it.

What mode of reproduction in fishes is described by each of the following terms: oviparous, ovoviparous, placental viviparous?

~These terms describe reproduction through internal fertilization. These are all different ways the mother supports the embryos. ~Oviparous is when large yolky eggs are laid soon after fertilization, and embryos are nourished by the yolk before hatching. ~Ovoviviparous is when the mother retains the developing young in the uterus while they are nourished by contents of a yolk sac until birth. ~Viviparous is when the embryos receive nourishment through a placenta of from nutrients secreted and produced by the mother

On the nineteenth-century notion of a "scale of nature," living amphibians were considered remnants of archaic terrestrial vertebrates largely superseded by "higher" forms including birds and mammals. Nonetheless, amphibian species are often more abundant and of longer evolutionary duration than avian or mammalian species. In what ways are amphibians unusually well suited for persistence?

~They can live both on land and in water. ~Their young live in the water, and as they grow, their body changes to suit life on land. ~They are ectothermic, they have glandular skin, and they breath through lungs, gills, or skin. ~Their skin is selectively permeable- allows for gas diffusion and passage of water. ~Being ectotherms and having permeable skin allows temperature adjustments of amphibians to be flexible. ~They can adapt to various environments and conditions by adjusting the concentrations of their bodily fluids.

In what ways are sharks well equipped for a predatory life habit?

~They have very sensitive senses to help with tracking prey. ~They locate prey using their lateral line system. It senses low-frequency vibrations with mechanoreceptors that extend along the sides of the body and over the head. ~Sharks also have great vision and are guided by the ampullae of Lorenzini to find the bioelectric field of animals. ~Both Jaws have many sharp teeth that are arranged in several rows, and those that are on the external row are shed. ~Their heterocercal tail provides speed and power. ~Their placoid scales reduce turbulence of water flowing over body when swimming, which increases speed.

How does the biological species concept differ from earlier typological concepts of species? Why do evolutionary biologists prefer it to typological species concepts?

~Typological species concept is the discredited, pre-Darwinian notion that species are classes defined by the presence of fixed, unchanging characters (+ "essence") shared by all members. ~Biological species concept is a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature. ~Typological species concept- species are defined by fixed essential features ~ Biological species concept- a species is identified according to reproductive properties of populations, groups of related organisms inhabiting a particular geographic area. ~The biological species concept is preferred because the biological species refers to more recent populations but ignores the species status of ancestral populations. Also, because species do not exist in groups of organisms that reproduce only asexually. Another reason is that systematists using the biological species concept often disagree on the amount of reproductive divergence necessary for considering two populations separate species.

What is "uniformitarianism"? How did it influence Darwin's evolutionary theory?

~Uniformitarianism is a principle established by Lyell. The principle consists of methodical assumptions that the laws of chemistry and physics have remained constant throughout the history of the earth, and that past geological events occurred by processes that can be observed today. ~Uniformitarianism influenced Darwin's evolutionary theory because it gave Darwin the idea that natural forces can explain different geological characteristics and features of earth.

Describe the functional anatomy of cephalochordates.

~no cephalization or brain, or sensory structures. Only photoreceptor cells. ~Notochord goes all the way to the anterior end. ~All five chordate traits. ~Wheel organ- cilia that bring food in through the mouth and velum to the pharynx. ~The hepatic cecum is for smaller food particles. ~Bigger food particles go into the intestine. ~Intestine not lined with muscle. Band of cilia moves food through. ~Food waste goes out of the anus. Leftover water is caught in the atrium and expelled out of the atriopore. ~Gonads release gametes into the atrium and leave through the atriopore. ~Separate sexes- diaceous. ~Circulatory system- no heart. The ventral aorta sort of functions like a heart; contracts, has muscle in it. ~Blood has no hemoglobin in it, nothing to bind the oxygen. Blood does not carry oxygen. ~Diffusion moves oxygen through the body. ~They have a closed circulatory system- blood always contained in blood vessels unless something makes them bleed.

Explain how biologists distinguish between experimental and comparative methods.

~the experimental method begins with a hypothesis that predicts how things will play out. That prediction is then tested through experiments, and the end results are compared with the prediction made at the beginning. ~the comparative method uses patterns to test hypotheses and uses phylogeny to look deeper into evolution processes through history.