Biology 200 exam 1

Define Evolution and Adaptation

-The gradual change in a species over time -the process of changing to fit a new environment or different conditions, or the resulting change

Explain the terms analogous structures and convergent evolution.

Analogous structures- similar characteristics occurring in organisms not representing homologous structure, but environmental constraints, (ex. Bats and insects have wings-does not mean they share a common ancestor) Convergent evolution- Similar forms arise within organisms because of similar selection pressures, (ex. White phenotype in arctic animals)

What was Aristotle's scala naturae?

Aristotle made a great chain of being which is a hierarchical structure of all matter and life, thought by medieval Christianity to have been decreed by god. The chain exhibits numerous figures from god to minerals in the earth.

Describe how prokaryotes carry out photosynthesis and cellular respiration when they lack compartmentalized organelles such as chloroplasts and mitochondria. This question will help you understand the endosymbiosis theory.

As well as specialized infoldings of the Prokaryotic plasma membrane ( aerobic prokaryotes infoldings function as mitochondria in cellular respiration and thylakoid membranes are found in cyanobacteria which function like chloroplasts to conduct photosynthesis).

Describe some limitations of the biological species concept, phylogenetic species concept, and morphological species concept.

Biological SC limits: species can interbreed, doesnt work with fossils or extinct or dead species, asexual reproduction (bacteria). Morphological SC limits: there can be morpho. variation between members of the same species. Phylogenetic SC limits: not useful in the field as collecting viable samples and preserving them could be difficult. Could be very expensive if a project doesn't have enough funding.

Explain why it is crucial to distinguish between homology and analogy before selecting characters to use in the reconstruction of phylogeny.

Both refer to similar characteristics between two separate species, but the major difference is how those changes came to be. HOMOLOGOUS traits are derived from two species having a common ancestral group that passed down those traits. This means those groups' lineage can be traced back and evidence supports they are related in some way. ANALOGOUS traits are derived from two separate species both developing similar traits due solely to adapting to similar environmental factors, and nothing to do with any ancestral link. Essentially, one species can seem like it is related to another, even though there is no recent common ancestor.

Describe the ideas of catastrophism, gradualism, transformism, and uniformitarianism

Catastrophism(Georges Cuvier)- theorizes the Earth has been shaped by SUDDEN, SHORT-LIVED, VIOLENT events Gradualism(James Hutton)- theorizes that change comes about GRADUALLY in nature as opposed to suddenly Transformism(Jean-Bapiste Lamarck)- theorizes that changes occur within a lineage population but that lineages do not split; there is no speciation. "Use + Disuse"+ "Inheritance of characteristics" Uniformitarianism(Charles Lyell)- theorizes the changes in the earth's shape during geological history have resulted from the action of continuous and uniform processes.

What do the accessory pigments do for plants and algae?

Chlorophyll B+C, carotenoids, and phycobilins aid in photosynthesis for photosynthetic organisms in different environments. They can also change the color appearance of organisms depending on the UV rays not being used/reflected.

Explain the difference between Darwin's Descent with Modification and our current definition of evolution.

Darwin's Descent with Modification does not take into account that, by our definition of evolution, it may be adaptation occurring and NOT evolution.

Define allopatric speciation. Describe the mechanisms that may lead to genetic divergence of isolated gene pools.

Definition: Geographic separation of populations from a parent species and subsequent evolution. Mechanisms: 1) Founder Effect, when a few individuals become isolated from their original population. 2) Bottleneck Effect, when an event, such as a natural disaster, causes a large portion of the population to die. 3) Disruptive Selection, when individuals in a population with both high and low phenotypic extremes are fitter than the intermediate phenotype

Name the supergroups of eukaryotes. You should be able to use your knowledge from the lab handouts to associate the Supergroups with an example. For example: Trypanosoma and Euglena are in Excavata. Red/green algae & plants are in Archaeplastida.

Excavata, Chromalveolata, Rhizaria, Archaeplastida, Amoebozoa, Optisthokonta

Explain what evidence convinced Darwin that species change over time.

Fossil records-dead birds that didn't reproduce were observed to have the unfavorable adaptations which is what led Darwin to the idea of natural selection-the key to how species change over time.

Describe how gene flow can act to reduce genetic differences between adjacent populations.

Gene flow can act to reduce genetic differences in adjacent populations because gene flow increases the movement of genes from different populations of species. The more interbreeding between the two populations, the more similar their genes.

Which supergroup contains organisms that have reduced mitochondria or non-functional mitochondria?

Group EXCAVATA, (parabasalida & diplomonads) possibly due to adaptation to environments with little to no oxygen, mitochon. No longer useful.

Explain how the existence of homologous and vestigial structures can be explained by evolution.

Homologous structures are structures that are in organisms that share the same basic form and vestigial structures are residual parts from a past common ancestor. These physical evidence support the ideas of evolution that these organisms all originated from a common ancestor who shared these traits or used the vestigial traits.

Explain why individuals cannot evolve. What is the smallest unit that can evolve?

INDIVIDUALS DO NOT EVOLVE, NOT POKEMON. Once you are born with god given traits they cannot be genetically changed over your lifetime. Evolution occurs over a large amount of time where once no generation shows any other trait than the one that has evolved, then it'll be considered as evolution. Smallest unit that can evolve is a population!

Describe primary endosymbiosis. Which Supergroup acquired their chloroplasts this way?

In a primary endosymbiotic event, a heterotrophic eukaryote consumed a cyanobacterium. Archaeplastida underwent primary endosymbiosis. (2 membranes around the plastid/chloroplast)

Explain the role of secondary endosymbiosis in the evolution of some Euglenozoans and organisms in Alveolates & Stramenopiles

In a secondary endosymbiotic event, the cell result from primary endosymbiosis was consumed by a second cell. (4 membranes). In Excavata(Euglenozoans), secondary endosymbiosis of green algae led to euglenid protists, while in the Chromalveolata(descendants of Alveolates&Stramenophiles) secondary endosymbiosis of red algae led to the evolution of plastids in dinoflagellates, apicomplexans, and stramenopiles.

Explain the role of population size in genetic drift.

Larger populations are unlikely to change this quickly as a result of genetic drift. Smaller populations are more likely to have quicker changes. bottleneck effect: when the size of the population is severely reduced. Founders effect: when a small group of individuals break off from a larger population to establish a colony.

Describe the evidence that suggests that mitochondria were acquired before chloroplasts in eukaryotic evolution. (Hint: look at the tree of all the supergroups and the idea of parsimony).

Majority of Eukaryotes have mitochondria even if they have plastids as well, meaning at some point they acquired the mitochondria and then acquired the plastid after.

Distinguish between a monophyletic clade and paraphyletic and polyphyletic groupings of species.

Monophyletic groups stem from a single point on the tree, i.e. a common ancestor. Paraphyletic groups are those in which not all descendants of a single common ancestor are included in the group. Polyphyletic groups are groups of organisms that share characteristics, rather than sharing a single common ancestor

List the five conditions that must be met for a population to remain in Hardy-Weinberg equilibrium.

NO: MNSMG(Make No Small Mistake Goose) mutation, natural selection, sexual selection, migration, genetic drift

Know the general features of a prokaryote and how they differ from eukaryotes.

No membrane-bound organelles No nucleus(circular dna) Ex. Bacteria, Archaea

Describe the life cycle known as alternation of generations. Does the ancestor to land plants, Charophytes, have alternation of generations?

Organisms that have multicellular diploid and haploid life stages. (sexual phase and an asexual phase). Charophytes DO NOT have alternation of generations.

Distinguish between prezygotic and postzygotic reproductive barriers.

PREzygotic, indiv. are prevented from mating (i.e. parts don't fit, mating rituals, bird calls) or if they mate, their gametes can't fuse. POSTzygotic, indiv. can mate but their offspring die or are infertile (ligers, mules)

Define the terms population , species, and gene pool

Population: all of the individuals of a species living within a specific area Species: group of populations that interbreed and produce fertile offspring Gene Pool: a collection of all the gene variants in the species.

Explain Stability, Reinforcement, and Fusion with regards to hybrids and parental species.

Reinforcement: barriers between two separate species are reinforced. Less Hybrids produced. Fusion: weakening of reproductive barriers, populations blend Stability: continued reproduction of hybrids.

Explain why bird and bat wings are homologous as vertebrate forelimbs but analogous as wings.

The overall structure of the wings and how they formed is different. Bat wings have longer "finger" bones that extend throughout the wing, and their wings are covered in skin and fur, while birds have very short finger bones and their wings are covered in feathers. The presence of similar bones indicates a COMMON ANCESTOR (homologous) that also had those bones. But the difference in the overall wing structure indicates that the wings themselves EVOLVED SEPARATELY(analogous).

Explain how reproductive barriers evolve. Describe an example of the evolution of a prezygotic barrier and the evolution of a postzygotic barrier.

They result from natural selection, sexual selection, or even genetic drift: The evolution of different mating location, mating time, or mating rituals: Genetically-based changes to these aspects of mating could complete the process of reproductive isolation and speciation. Prezygotic example: Fruit flies on different mediums showed assortative mating. Flies on one medium prefer red eyes (?). The flies on the other preferred black eyes (?) Postzygotic example: Mules are infertile, stopping further generations from continuing.

Explain "use and disuse" & "inheritance of acquired characteristics" for evolutionary change proposed by Jean Baptiste Lamarck. Explain why modern biology has rejected Lamarck's explanation for descent with modification

Use and Disuse concept theorizes that changes occur within a lineage population but that lineages do not split, the organisms simply stop using certain characteristics and that passes on to the offspring. Within modern biology, such concepts have been unsupported for a while as we've learned that organisms best fit from their population get to pass on their genes, which make up the next generation

What is heterozygote advantage?

describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype.

Explain how Hutton's principle of gradualism and Charles Lyell's principle of uniformitarianism influenced Darwin's ideas about descent with modification.

The important detail about the principles is that they theorize a gradual SLOW change over time which influences Darwin to observe how the finches became so speciated with common ancestors

Describe the observations that lead Darwin to propose natural selection as a mechanism for descent with modification.

"Darwin observed species of organisms on different islands that were clearly similar, yet had distinct differences. For example, the ground finches inhabiting the Galápagos Islands comprised several species with a unique beak shape. The species on the islands had a graded series of beak sizes and shapes with very small differences between the most similar. He observed that these finches closely resembled another finch species on the South American mainland. Darwin imagined that the island species might be species modified from one of the original mainland species. Upon further study, he realized that each finch's varied beaks helped the birds acquire a specific type of food. For example, seed-eating finches had stronger, thicker beaks for breaking seeds, and insect-eating finches spear-like beaks for stabbing their prey." -Open Stax

Explain how an essay by the Rev. Thomas Malthus influenced Charles Darwin.

"The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers. Thus, there is competition for those resources in each generation. Both Darwin and Wallace's understanding of this principle came from reading economist Thomas Malthus' essay that explained this principle in relation to human populations." -Open Stax basically, gave him the idea that organisms that aren't on top of their game are going to die because of a lack of resources.

What is Darwinian fitness? How is this different from how non-scientists use this word?

"The contribution an individual makes to the gene pool of the next gene pool of the next generation relative to the contribution of other individuals." Non-scientists use the word loosely to describe how physically fit an organism is relative to their environment.

Be able to explain how each of the 5 mechanisms can cause a population to evolve

1. Mutation 2. genetic drift 3. gene flow 4. non-random mating 5. natural selection

Explain the statement: "A phylogenetic tree represents a hypothesis about evolutionary relationships."

A phylogenetic tree represents a hypothesis because it is derived from existing evidence: data collected through observation of morphological or genetic traits. Because it is a hypothesis, it can change over time as new evidence presents itself.

Explain the statement "It is the population, not the individual, that evolves."

A single organism cannot evolve by itself. Natural selection is survival of the fittest, so the adaptations are relative to each other.

Be able to distinguish between the biological species concept, the morphological species concept, and the phylogenetic species concept.

A) Biological species concept: species organized due reproductive isolation. Individuals of the same species can interbreed in nature and produce viable, fertile offspring. Most commonly used speciation. (Geographical isolation does not equal reproductive isolation i.e. ppl in Russia lmao) B) Morphological spec. con.: organisms with different morphologies are different species. Individuals of the same species share physical features/measurable anatomical criteria. Works for extinct organisms/dead organisms, and if all you have is morpho. Info. (NOT useful when a single species has morpho variation.) C) Phylogenetic Spec.Con.: Identifies genetically unique groups. Can be used for living or extinct species. NOT useful in the field or on a budget.

Distinguish between allopatric and sympatric speciation.

Allopatric: result of being in different areas. 2 types. Dispersal & colonization/migration. Vicariance-change in landscape/environmental In both cases, the physical barrier is UNCROSSABLE. (physical separation does not lead to new species i.e. ppl in Russia lmao Sympatic: groups NOT physically separated. More common with plants

Describe the evidence that supports the theory that mitochondria and plastids evolved by serial endosymbiosis. Explain what living organisms are likely relatives of the prokaryotes that gave rise to mitochondria and plastids.

Relatives of the prokaryotes that gave rise to plastids: Land Plants, Red Algae, and Green Algae Relatives of the prokaryotes that gave rise to mitochondria: All Eukaryotes have mitochondria or had them Plastid (Chloroplasts): Have a double membrane (from cyanobacteria) Have circular chromosomes like bacteria Split to produce new chloroplasts inside the eukaryotic cell Have chlorophyll a as the primary pigment Use water as an electron donor in photosynthesis Release free oxygen during photosynthesis Mitochondria evidence: Surrounded by 2 membranes (trait found in bacteria) Contain a circular chromosome Make their own ribosomes Split to produce new mitochondria

Explain why the kingdom Protista is no longer considered a legitimate taxon.

Scientists now naming taxa as groups of organisms thought to include all the descendants of a last common ancestor (monophyletic group), some protists have been discovered to be more related to animals, plants or fungi than they are to other protists, making the kingdom "Protista" polyphyletic as the descendents all come from more than one common ancestor---therefore not suitable for placing them in the same taxon

Describe examples that illustrate adaptive radiation.

The honeycreeper birds illustrate adaptive radiation. From one original species of bird, multiple others evolved, each with its own distinctive characteristics, all adapted separately to eat their own food.

What does it mean that natural selection acts on the individual? Or acts on the phenotype? Or "grades on a curve"?

When natural selection acts on an individual, it is selecting those with a higher overall fitness compared to the rest of the population. When it acts on the phenotype, the physical characteristics that give an organism a reproductive advantage may become more common in a population. Grades on a curve: Stabilizing selection: Intermediate phenotypes have the highest fitness, and the bell curve tends to narrow. Directional selection: One of the extreme phenotypes has the highest fitness. The bell curve shifts towards the more fit phenotype. Disruptive selection: Both extreme phenotypes have a higher fitness than intermediate phenotypes. The bell curve develops two peaks.

Define sympatric speciation

When two species diverge while living side-by-side.

Describe five prezygotic reproductive barriers and give an example of each.

spatial isolation: populations that are separated by great distances Ex. , a cricket population that was divided after a flood could no longer interact with each other. temporal isolation: two species breed at different times. Ex. two frog species inhabit the same area, but one reproduces from January to March; whereas, the other reproduces from March to May mechanical isolation: Female and male sex organs are not compatible. Ex. damselfly males of different species have differently shaped reproductive organs. gametic isolation: Female and male gametes are not compatible. Ex. there's no example of this in the book, but y'know, sex cells don't do the Dew™ behavioral isolation: no mate recognition between females and males of the different species Ex. Various firefly species display their lights differently