SDSU BIOL-101 World of Animals Ekdale Exam 1

taxon

any named group of organisms (plural = taxa)

homology

similarity based on common ancestry

clade

natural taxon based on common ancestry; by definition, all clades are monophyletic groups

cladogram

branching diagram of ancestor-descendant relationships

sister taxa

descendants of a recent common ancestor

synapomorphy

derived characteristic that is shared among two or more taxa

pseudopod

cytoplasmic extension used for locomotion and feeding in amoebas

cilium

hair-like structure used for movement of particles or locomotion of some unicellular organisms

flagellum

whip-like structure that is used for locomotion of some unicellular organisms

Carolus Linnaeus

established rules of taxonomy, including the binomial nomenclature system of naming species

Willi Hennig

founded phylogenetic systematics, which categorizes species based on common ancestry

Lynn Margulis

proposed the theory of endosymbiosis to explain the origin of eukaryotic cells

List the four most common mechanisms (theories) of evolution and briefly define each.

(1) Mutation - random change to a genetic sequence

(2) Migration - genes move from one population to another

(3) Genetic Drift - random sampling error of genes over generations

(4) Natural Selection - genes code for observable traits (phenotypes) that increase an individual's survivability and reproduction will become common in a population

What is taxonomy, and why is it important? (I.e., why am I having you learn so many names in this class?)

Taxonomy is the ordering and naming of organisms. Taxonomy is important, because most species are undescribed (unnamed), many species are disappearing, systematic (categorical) data need to be organized, it gives species unambiguous names, it clearly depicts the diversity of life on Earth, and aids in the management and preservation of Life.

What is binomial nomenclature? [Be sure to recognize and use binomial nomenclature.]

Binomial nomenclature is the system of naming species with two elements: the genus name (first letter capitalized) and the species epithet (not capitalized). Both elements are italicized.

How are taxa defined in Linnean taxonomy versus phylogenetic systematics?

Taxa are defined by overall physical similarity in Linnean taxonomy, but taxa are defined by common ancestry in phylogenetic systematics.

Define a monophyletic group.

A monophyletic group consists of an ancestor and all of its descendants.

What is the major difference between monophyletic and non-monophyletic groups? [Be prepared to identify each on cladorams.]

Both monophyletic and non-monophyletic groups contain a recent common ancestor, but non-monophyletic groups contain some but not all of the descendants of the ancestor, whereas a monophyletic group contains all descendants.

What is the geologic age of the oldest prokaryote fossils, which represent the earliest forms of life on Earth? What modern organism do they resemble?

The earliest fossils are approximately 3.5 billion years old and they resemble living cyanobacteria ("blue-green algae").

List the three major clades of Life. To which clade do you (as an animal) belong?

(1) Bacteria; (2) Archaea; (3) Eukaryota. Animals are members of Eukaryota.

List the synapomorphies of Eukaryota.

The synapomorphies of eukaryotes include a membrane bound nucleus and membrane bound organelles.

Why isn't the group "Prokaryota" (group containing all prokaryotes) considered to be a monophyletic group?

"Prokaryota", a group consisting of all prokaryotes, is non-monophyletic, because some prokaryotes (Archaea) share a more recent common ancestry with eukaryotes than others.

Why isn't the group "Protista" considered to be a monophyletic group?

"Protista" is a non-monophyletic group, because not all protists share a more recent common ancestor with non-protists than other protist species.

How do plants, fungi, and animals differ in how they obtain energy?

Plants are autotrophic and produce their own energy from sunlight through photosynthesis (producers). Fungi are heterotrophic and consume their energy through absorptive nutrition (decomposers). Animals are heterotrophic and consume their energy through ingestive nutrition (consumers).

What organism is the sister taxon (closest living relative) to animals? How do you know?

The sister taxa to animals are the choanoflagellates, which resemble the collar cells found in animals (especially sponges).

What is the theory of endosymbiosis?

The theory of endosymbiosis, which was popularized by Lynn Margulis, explains the origin of eukaryotic cells through the consumption of autotrophic bacteria and cyanobacteria by heterotrophic prokaryotes. The consumed bacteria and cyanobacteria became mitochondria and chloroplasts. Support for the theory includes the double membranes of mitochondria and chloroplasts, as well as the independent DNA of mitochondria and chloroplasts.

fact

observation that has been repeatedly confirmed

hypothesis

tentative statement or proposition about a natural phenomenon that can be tested by observation or experiment

theory

highly probable, well-tested and substantiated explanation of a natural phenomenon based on a large collection of observations and experiments

mutation

random change to the sequence of a gene [mechanism of evolution]

migration

movement of an individual (and its genes) from one population to another [mechanism of evolution]

genetic drift

random sampling error over generations [mechanism of evolution]

fitness

ability for an animal to survive and reproduce

adaptation

trait that increases an individual's survival and reproduction (increases fitness)

speciation

process by which new species arise

vicariance

population is geographically divided by a physical barrier

dispersal

individuals migrate from one population to a different area

Charles Lyell

popularized the idea of uniformitarianism ("present is key to the past")

Jean-Baptiste Lamarck

hypothesized the inheritance of acquired characteristics

Charles Darwin

developed the theory of natural selection to explain evolution

Gregor Mendel

founded genetics; recognized inheritance of dominant versus recessive traits

What is the definition of modern science?

Modern science seeks to find natural explanations for natural phenomena.

List the three attributes of science. [Be able to identify appropriate scientific hypotheses and theories]

Science must be (1) testable, (2) repeatable, and (3) falsifiable.

What are the five steps of the hypethetico-deductive approach to science?

(1) observation, (2) question, (3) hypothesis, (4) empirical test, and (5) conclusion.

What is the modern definition of evolution (including information from genetics)?

Evolution is the change in gene frequency within a population from one generation to the next.

Is evolution a fact or a theory?

Both! A change in gene frequency within a population from one generation to the next (definition of evolution) can be observed (fact), but the explanation of how and why gene frequencies change is theory (mechanisms such as natural selection)

What is natural selection?

Natural selection is a theory of evolution stating that heritable traits that are beneficial to the survival of an individual are selected and become common in a population.

What is the most common mechanism of evolution?

The most common mechanism of evolution is natural selection.

What is the major difference between allopatric and sympatric speciation?

The major difference between allopatric and sympatric speciation is geographic isolation during allopatric speciation, but the population is continuous during sympatric speciation.

What must be present in a population before evolution can occur? (In other words, what is the prerequisite or "raw material" of evolution?)

The prerequisite for evolution to occur within a population is genetic variation.

List Charles Darwin's 4 "postulates" that contribute to natural selection. (I.e., under what conditions will natural selection be the logical outcome?)

(1) individuals within populations are variable; (2) variations among individuals are heritable; (3) in every generation, some individuals are more successful at surviving and reproducing than others ("fitness"); (4) survival and reproduction are nonrandom.

What is the relationship between an organism's genotype and phenotype?

The genotype of an organism is the genetic sequence that codes for an observable trait, and the phenotype is the observable trait itself (product of gene expression).

Does natural selection act on individuals or populations? Does it act on phenotypes or genotypes?

Natural selection acts upon the phenotypes of individuals, but evolution consists of changes within the genotypes of the population.

Explain the comparative and experimental methods to answer zoological questions?

In the experimental method, variables are manipulated in an experimental group and compared to a control group.

In the comparative method, observations are compared to those predicted by a hypothesis.

Macroevolution

Evolution above the species level; caused by speciation (large scale)

Microevolution

Evolution within a single population (small scale)