Evolutionary Biology Term Test 1

Theodosius Dobzhansky

Nothing makes sense except in the light of evolution. It’s really satisfying.

Biological evolution

The study of the processes by which life evolves and the pattern these processes have generated over the past 5 billion years

Cetaceans

Whales, dolphins, fishlike bodies, use relatively small amounts of energy to shoot through water. Generate thrust from tail moving side to side like sharks. Embryos develop in the uterus, forming placentas, and have tiny bones in flesh where hip would be on land.

Homology

Structural characters that are shared because they are inherited from a common ancestor

Baleen

Swim around and catch fish. Get huge amounts inside, like entire schools. One giant mouthful, water squirts back out through combs, leaving just the krill.

Dorudon

In teeth, is more similar to living mammals than to living odontocetes. Sees the first reduction in hindlimbs.I

Involucrum

Part of the ear in modern dolphin and pakicetus

Pakicetus

Split from dolphins. Fossils found where dolphins reside today.

¹⁸O/¹⁶O ratio

Higher in saltwater and teeth of marine animals. Shows how the switch from freshwater to seawater.

Whale’s synapomorphies

Mammary glands, three middle ear bones, and hair in developing embryos

Convergent evolution

Similarities with/between whales and fish. Attained similar traits seperately, homoplasy

Asragalus

In our ankle between the tibia and fibula. Shows common ancestry between hippos and dolphins/whales

Phylogeny

Branching patterns of evolution, synthesize evidence of a complex evolutionary history

Morphological

Form and structure of organisms

Indohyus and pakicetus

Had dense bones found in hippos. Able to stay underwater. They likely swam like otters, kicking large feet that they dragged on land. (later became obsolete, even costly.)

Cetacean brains

Biggest brain proportional to body (besides human). Earliest whales had relatively small brains. Only after water did they change drastically, as they started living in large social groups, forming alliances.

Mysticetes

Trapped small animals with their baleen

Odontocetes

Swam after fishes and larger prey, echolocation

SARS-Cov-2

50-140 nm diameter and 1000x smaller than width of hair. 26 protein coding genes.

Influenza virus

Membrane and proteins shell encasing strands of RNA. Invades host cell. Hemagglutinins bind to receptors of epithelial cells in host respiratory tract. Triggers cell to open and then move inside the virus and mass produce copies of themselves.

SARS-Cov-2 lifecycle

Spike bind to ACE-2 receptor, allows for certain things to pass, fool to gain entry, opens and excretes RNA genome. Can’t replicate so it uses ribosomes and mechanisms to copy all its genes. Creates spike proteins and is ejected.

Viral reassortment

Viruses swap genes, undergo gene shuffling (2 viruses) and become packaged into protein shells. Surface proteins are distinctly different, and humans lose immunity to it. Added urgency to detecting new flu strains

H7N9

Spread from mostly bird to human, rarely from human to human. Quite deadly. Most common antivirals weren’t doing anything.

Humans and chimpanzees

Share common ancestry. We’ve existed for like 5-7 million years, but in evolutionary terms that is considered pretty recent. That amount of divergence and we’re still 99% identical to what they are.

Macroevolution

Evolution across millions of years

Microevolution

Allele frequencies change across generations

Plato

Typological thinking. Every organism is an example of a perfect essence or type, created by God. Believed that types were unchanging.

Aristotle

Ordered organisms into linear great chain of being (or scale of nature)

The great chain of being

Species were put on a scale of lowest to highest forms and were fixed types. Plants were the lowest form of life, humans listed as higher due to ability to reason, and it was seen as God’s creation of it. Increasing size and complexity.

Linnaean classification

Discovered/introduced taxa and taxonomy. Assigned every species to a particular genus, family or order based on traits it shared. There was a belief of hybridization coming after the bible. Nested hierarchy. Gets further out and more and more inclusive.

Nicholas Steno

Dutch anatomist who dealt with things like fossil records. After sharks died, teeth were transformed to snow. Sedimentation over mountains were things originally on the ocean floor.

Stratigraphy

Studying the layers of the earth

Natural theology

Building on classic work and anatomical research in ancient Greece. Studied organs and functions. Compared old hearts of humans, snakes and fish to what had been drawn up in ancient Greece to current hearts.

Mechanical function

Seen as evidence of God’s divine creation. Complex organs were noted and later the powerful explanation of Darwin emerged through evolution by natural selection.

Buffon

Thought the world form was due to laws of physics, was only 70 000 years old. We also saw the idea of small particles between rocks and humans being the same.

George Cuvier

Compared elephants from Africa and India, and the idea of extinction. Fossils resemble modern species, and many were extinct. Mapped out the geology of other parts of the world, discovering that formations of rock exposed in one country could be found in others.

Extinction

Left blanks in the great chain of being

Mary Anning

British Naturalist, discovered many early fossils and the concept of extinction was met with considerable resistance

James Hutton

Scottish chemist and geologist. Rocks formed through imperceptibly slow changes, many of which we can see around us today. Small changes accumulated over time, and so he believed the Earth was very old.

Smith

Organized strate by oldest to youngest (fossils) and began forming a geological history. Answers for extinction in rocks below. Created the first geological map. Same layers of rock in different parts of England.

Lamarck’s theory of evolution

Life was driven from simplicity to complexity. Became popular because it was intuitive, however biologists rejected it because of how it was phenotypically related to genetic mechanisms of inheritance

Uniformitarianism

Same observable natural processes today were also responsible for events in the past. Slow process of erosion over long time, can produce massive canyons. Torrential rain, impromptu stream set up with water, can end up forming a trench.

Homology

Born based on the idea that we were all cousins and how we have very similar bone structures even with different functions. Also known as a synapomorphy.

Homologous trait

Similar due to inheritance from a common ancestors (humans begin to form gill arches)

Malthus

Believed poor people naturally selected against, which led to Darwin and Wallace’s hypotheses. A grim proposal.

Wallace

Proposed similar evolutionary ideas, collections from South America and Malay Archipelago, observations of biodiversity, common ancestry, natural selection.

Darwin and mating behaviour

Mating effects sexual selection. How fast embryos grow is affected by selection. Darwin liked heredity and genetic to select for traits, and then later on (1950s) DNA and the double helix was discovered.

Artificial selection

Humans are selective agents (breeding), and they exaggerate traits not seen in nature. Breeders can do it, so can we with nature.

Moment of catastrophe

The resources and population meet, there is not enough to sustain population and the population will crash.

Darwin postulates

1. Individuals within a species are available

2. Some variations are passed to offspring

3. In ever generation, more offspring are produced than can survive

4. Survival and reproduction is not random

Kelvin

Argued the earth was no more than 20 million years old. He was proved incorrect. He thought since the Earth was hot and had been cooling, then it must still be young, but the earth is not static. Movement of tectonic plates has changed the way the earth heats up and down.

Carbon-14

half life is 5730 years. 50% of it will become Nitrogen-14 in 5730 years.

Radioactive substances still on earth

Samarium-147, Rubidium-87, Rhenium-187, Thorium-232, Uranium-238

Countershading

Cancels out darkening shadows, makes it harder for predators to see them (smaller animals)

Computed tomography (CT scanner)

Where we resonate and produce sounds and just analyze what things sound like

Lump of coal

Remains of dead plants

Biomarkers

How plant materials are transformed, how we know the age, sediments.

Stromatolites

Large mounds built today by colonies of bacteria, grown on floors of lakes and shallow seas. Form when biofilms of microorganisms, especially cyanobacteria, trap and bind sediments to form layered accretionary structures

Enigmatic species

Edicaran fauna. Measuring a whole meter in length, looked to be like snails and clams. Only distantly related to these lineages though. Independently evolved multicellularity.

Teleosts

Most species of fish on earth came from this 350 million years ago

Synapsids

Dominant vertebrates relative to today’s mammals (sprawling creatures) came around 200 million years ago.

Hominin evolution

Key genetic and behavioural changes. 7 millions years old.

Weald

Identified stratigraphy in the rolling hills and valleys in England

Dating Earth’s layers

Geologists identified numerous rock layer around world (1800), mapped layers into chronological order. This estimated the earth to be 4.56 billion years.

Phylogeny

Evolutionary history of a lineage. Can depict populations, genes, species or higher taxonomic units.

Phylogenetic tree

Visual representation of phylogeny, can look different and depict the same thing. Don’t read along tips, look for common ancestry.

Node

Links kinship, or “same parent” of two different species, represents common ancestors of all descendent lineages

Internal nodes

Located within the phylogeny, representing ancestral populations or species that have long since disappeared.

Clade

Node and all of its descendants

Cladogram

Shows only the relationships among species

Taxa

Units of classification

Branch

Separates a group, lineages evolving over time. Connects successive speciation events or other branching events.

Monophyletic

Group of an organism and all of its descendants

Polyphyletic

Cutting the tree in two. Shared characteristics, grouping not based on common ancestor.

Paraphyletic

Includes some but not all descendants of a common ancestor

Carnivorans

Group of mammals, enlarged side teeth, shear meat off their prey

Synapomorphies

Shared derived characters, evolved in the immediate common ancestor

Outgroup

How we decide what is an ancestral and what is derived. Seeing which groups don’t fit within the clade.

Homoplasy

Similarities of independent evolution of same trait in two or more lineages

Evolutionary reversal

Derived states return back to their ancestral state on some of the branches

Parsimony

Simplest explanation for set of data is chosen as the hypothesis (not always correct explanation, but can be true).

Consensus trees

The computer selected trees based on all information

Polytomy

Comb shaped set of branches, used to represent unresolved relationships in the tree (3 split)

Nested hierarchy

Further you go back, the more inclusive you get. Katy Perry Comes Over For Good Soup.

Homologous traits

Lobe fins and tetrapods are linked by these, and most interesting in the limbs

Lobe-fins

They (as opposed to ray fin) have a chain of sturdy bones anchoring it. There was a bunch of bony projections and that was how they swam. We still have it, but the extension of several different bones as well.

Coelacanth

Discovered in 1938, was important because of how they move their fins like mammals move their limbs

Tiktaalik

Discovered in 2004, was part fish part tetrapod, like a fish with feet and fins far more elongated than Coelacanth. Scales, gill, flat head, unusual fin (walking).

Zhenyuanlong

Vaned feathers, projections off the quill form a code. All the feathers stick together and create the strength of flight. Strong but weigh very lightly.

Archaeornithura

Birds don’t have bony tails, they had a fanned tail like modern birds

Characters

Identifiable heritable traits

Character state

Condition of the character

Ancestral characters

What character was in pas ancestors (primitive)

Derived characters

What character is more advances and does not come from past ancestors

HGMA2

Carrying two copies increases height by 1 cm and the researchers have since discovered 800 loci that influence height

Gene

DNA, unit of inheritance, codes specific proteins

Proteins

Makes up most the cell, dry weight. Structure and chemical reactions in the cell. Some carry information and molecules (hemoglobin w/ oxygen). They are all made up of the same 20 amino acids.

Messenger RNA

Transcript copy of gene, encodes specific polypeptide

Ribosomal RNA

Primary component of ribosome, catalytic activity

Transfer RNA

Carries amino acid to ribosome for translation