lectrure 3- evidence of evolution Flashcards
what are the 2 definitions of theory regarding science?
Theory (1): A hypothesis propose as an explanation; hence a speculation, conjecture; an idea or set of ideas about something; and individual view or notion.
Theory (2): A scheme or system of ideas or statements held as an explanation or accounts of a group or facts or phenomena;a hypothesis that has been confirmed or established by observation or experiments and is propounded or accepted as accounting for the known facts; a statement of what are held the general laws, principle, or causes of something known as observed
what is a theory in science? and what are some theories?
“A hypothesis that has been confirmed or established by observation or experiments and is propounded or accepted as accounting for the known facts (…)”
Heliocentric theory
Gravitational theory (Newton’s Law of Gravity)
Big Bang Theory
Cell theory
Theory of plate tectonics
Theory of Evolution
define domestication
Domestication refers to the process by which wild animals or plants are selectively bred and managed by humans for specific purposes, leading to changes in their genetics, behavior, and morphology. It involves the adaptation of wild species to live and reproduce in human-controlled environments, such as farms, households, or other managed settings. Domestication typically results in traits that are desirable to humans, such as increased docility, productivity, or nutritional value.
define artificial selection
Artificial selection, also known as selective breeding or human-directed evolution, is a process by which humans intentionally select and breed organisms with desired traits to produce offspring with those same traits. This process mimics the natural selection mechanism observed in the wild but is directed by human preferences or goals rather than natural environmental pressures
who breeds in natural selection?
In natural selection you don’t need a breeder, you don’t need a selector, survival will do it for you
what is macro evolution?
It refers to larger changes over a long-time scale.
what is the path to macro evolution showing us for certain fish?
*That fishing rod has been shaped by selection by the eyes of generations of prey fish
*The ones that look most like wriggling worms, were most successful in luring prey
what does survival determine for natural selection?
Survival is all it takes to determine the non-random survival of genes that made the desirable characteristic
As the generations go by, the number of genes that are successful in building bodies that are good at surviving, are the ones that we see in gene pools in species all over the world.
what are some different forms of evidence for evolution?
Anatomy: Species may share similar physical features because the feature was present in a common ancestor
Fossils: They document the existence of now-extinct past species that are related to present-day species
Natural history: Traits present in organisms can be understood only in view of their evolutionary path
Embryology: Traits present in organisms can be understood only in view of their evolutionary path
Biogeography: The global distribution of organisms reflects evolution and geological change
how does anatomy relate to proof of evolution?
Organisms often look similar in their morphology
what is homology? what does it show?
the relatedness of life forms
two traits that have descended from a common ancestral character
such as the wings of a bat, arms of a human, legs of a cheetah or fins of a what having the same bones
what is homology and analogy?
Homology= the relationship of any two traits that have descended from a common ancestral trait
Analogy= The relationship of any two traits that have descended from “unrelated” ancestors through convergent evolution
Homologous structures provide evidence for common ancestry
what is a fossil? and what are the different types?
A fossil is the preserved remains of a once-living organism.
Petrified Fossils
Molds and Casts
Carbon Films
Trace Fossils
Preserved Remains
what do Fossil records show us?
Fossils in older layers are more primitive than those in the upper layers
*Most recent fossils more resemble extant species
*Species change over time
*Transitional forms in major groups *Variation within each species
*Cases of imperfect adaptation
what is the Principle of superposition
These early geologists simply ordered the different layers of rocks that they found
Deeper layers must have been laid down before the shallower ones
Use fossils to cross-correlate different locations
how do we determine a fossil’s age?
Fossils are generally only found in sedimentary rocks
We can calculate the date of formation of the igneous rock, using radioactive isotopes decay
what are the half-lives of important elements?
Element Half-life
Uranium-4.5 Billion years
Californium- 800 years
neptunium- 1hour
Plutonium- 5 hours
Americium- 25 minutes
Nobelium- 3 seconds
Carbon- 5730 years
Carbon-740 milliseconds
how old is the planet?
The planet is 4.6 billion years old
order the different periods of evolution
1- archean
2- proterozoic
3- paleozoic
4- Mesozoic
5- Cenozoic (with humans)
what is the missing link of fossil evolution?
The concept of a “missing link” in fossil evolution refers to a hypothetical transitional fossil that would fill a perceived gap in the fossil record between two different species or lineages. It’s important to note that this term is somewhat outdated and can be misleading, as it implies that there is a single fossil that is crucial for understanding evolutionary relationships. In reality, the fossil record is complex and incomplete, and our understanding of evolutionary relationships is based on a large body of evidence rather than a single fossil.
In paleontology and evolutionary biology, scientists use the term “transitional fossil” instead of “missing link.” Transitional fossils are fossils of organisms that display traits that are intermediate between those of their presumed ancestors and descendants. They provide valuable evidence for evolutionary transitions and the gradual change of species over time.
While there are certainly gaps in the fossil record, scientists have discovered numerous transitional fossils that provide insight into various evolutionary transitions, such as the evolution of whales from land-dwelling ancestors, the evolution of birds from theropod dinosaurs, and the transition from fish to tetrapods (four-legged vertebrates).
It’s also worth noting that our understanding of evolution is not solely based on the fossil record. Other lines of evidence, such as comparative anatomy, embryology, genetics, and biogeography, contribute to our understanding of evolutionary relationships and processes. Overall, while there may not be a single “missing link” fossil, the cumulative evidence from multiple sources allows scientists to reconstruct the history of life on Earth and understand how different species are related to one another
what does Evidence from fossil record provide?
The fossil record provides valuable evidence for understanding the history of life on Earth and the processes of evolution. Here are some key contributions of the fossil record:
Documentation of Extinct Species: Fossils provide direct evidence of organisms that lived in the past but are now extinct. By studying these fossils, scientists can reconstruct the diversity of life forms that have inhabited the Earth throughout its history.
Transitional Forms: Fossils often preserve intermediate or transitional forms between different groups of organisms. These transitional fossils provide evidence for evolutionary transitions, such as the evolution of whales from land mammals, the evolution of birds from theropod dinosaurs, and the transition from fish to tetrapods (four-legged vertebrates).
Chronological Sequence: Fossils are dated based on the layers of rock in which they are found, allowing scientists to establish a chronological sequence of life forms over time. This chronological sequence helps researchers understand the timing and pace of evolutionary events and the order in which different groups of organisms appeared and diversified.
Biogeographic Patterns: Fossils found in different regions of the world provide information about past geographic distributions of species and changes in Earth’s continents and environments over time. This evidence helps scientists reconstruct past environments and understand how organisms have migrated and adapted to changing conditions.
Evidence of Extinction Events: Mass extinctions, such as the one that marked the end of the Cretaceous period and the extinction of non-avian dinosaurs, are documented in the fossil record. Studying these extinction events can provide insights into their causes and consequences and help predict future patterns of extinction in response to environmental changes.
Evolutionary Trends: Fossils reveal patterns of evolutionary change over long periods of time, such as trends in body size, shape, and complexity. By studying these trends, scientists can infer the processes driving evolutionary change and the selective pressures that have shaped the diversity of life on Earth.
what can we learn about evolution regarding the whale?
Evolution of snout-blowhole
The evidence for the evolution of whales from land-dwelling ancestors comes from a combination of:*fossil evidence, *comparative anatomy, *and genetic studies
What do fossils teach us?
Confirm several predictions of evolutionary theory:
*gradual change within lineages *splitting of lineages
*the existence of transitional form
We find transitional forms in the fossil record precisely where they should be
Evolutionary change, even of a major sort, always involves remodelling the old into the new
legs of land animals ➔limbs of ancestral fish
Mammal’s middle ear bones➔jawbones of reptilian ancestors
Birds’ wings ➔the forelegs of dinosaurs
does natural selection occur with new material?
no
Natural selection can act only by changing what already exists
New species will be modified versions of older ones
what are Remnants: Vestiges, Embryos, and Bad Design
Within the bodies of animals and plants, lie clues to their ancestry, that are testimony to evolution
where did most flightless birds evolve?
Most of the flightless birds evolved on islands due to inaccessibility
All places without mammals or reptiles predators!
what is a vestigial trait?
A trait of a species that was an adaptation in its ancestors, but that has either:
*lost its usefulness completely
*has been coopted for new uses.
Ostrich’s wings don’t help to fly but:
-Stabilise run
-Threat display
-Mate dance
In birds, despite the use, the wings are made with the same bone
penguins- swimming
Kiwis- nothing
praying mantis- Display
why might animals evolve away from flight
Flight is metabolically expensive, and if:
*No predators
*Food readily obtained on the ground
➔Flight energy can be diverted to reproduction or food
➔Reduce the chance of injuries
Natural selection would directly favour mutations that led to progressively smaller wings, resulting in an inability to fly.
what is a Vestigial trait
An anatomical feature (or behaviour) that no longer seems to have a purpose in the current form of an organism of the given species
what is atavism?
Atavism: trait reverting to ancestor form
what are pseudogenes?
Non-coding sequences similar to working genes
why is Comparative embryology important?
Ernst von Baer (1828):
*The more closely related any two species are, the more similar their development as embryos.
*Closely related species have similar embryological development
*Structure in embryo stage with no purpose and not present in adult
*Development diverges following weird routes…
what is some Comparative embryology in vertebrates?
All vertebrates pass by the same developmental stages, all have:
*Branchial arches
*Tails
*Simple heart and circulatory system
Gill slits / branchial arches
Fish: Jaw and gills
Human: tiny bones of the middle ear, the Eustachian tube, the carotid artery, the tonsils, the larynx, and the cranial nerves
what is the similarity in the vertebrate embryology of the circulatory system/kidney in invertebrates
Circulatory system/ Kidney: Starts fishlike ➔similar to embryonic amphibians ➔resembling that of embryonic reptiles ➔true mammalian circulatory system
what is the reason for comparative embryology?
As one species evolves into another, the descendant inherits the developmental program of its ancestor and all the genes that form ancestral structures. “Adding new stuff onto old” principle
And this makes sense only if species have an evolutionary history
how is imperfection evidence for evolution?
Every species is imperfect in many ways
Issues that only humans have: Fractured hips, bunions, hernias, fallen arches, torn meniscuses, shin splints, herniated discs, spondylolysis, scoliosis… and more
Bad design: Recurrent Laryngeal Nerve
branch of the vagus nerve that supplies motor function and sensation to the larynx.
In fish, the nerve heads straight from the brain, down to the larynx
However, it is inefficiently evolved in mammals as it goes down to the heart and then back up to the larynx.
Possible explanation: Evolution doesn’t start from scratch. Organisms evolved features present in their ancestor
And this makes sense only if species have an evolutionary history
what is biogeography?
“ the study of what organisms live where on earth and why”
Biogeographical patterns provide clues about how species, both alive and extinct, are related to each other.
what is a biome?
A biome is an area classified according to the species that live in that location
what is a reasonable non-evolutionary prediction?
A reasonable non-evolutionary prediction is that species should occur wherever their habitat is. However:
*Regions with identical climates have different floras and faunas
*Geographic barriers associated with breaks between taxonomic groups.
*Within a region, organisms are often closely related even across environmental gradients
why do places have Similar Climate and Different Taxa?
Taxa are very different, but in similar environments they cover the same niches with similar aspect
convergent evolution: The evolution in different taxa of structures that are similar, NOT originated by common ancestry, due to similar selective pressures.
an example is Cacti and Euphorbs
or placental mammals and austrailian marsupials
how do we know the supercontinent was real?
The earliest marsupial fossils (130 MYA) are found in in North America
*They arrive in Australia 50 MYA
*How did they do it??
Proof: Extinct marsupial family Polydolopidaefound in Seymour island
Oceanic islands
*Have a large number ofendemic species
*Miss many native species on continents
*Many species are very similar even if ecologically diverse
*Species are similar to ones on the closest continent
*Endemic species can disperse
Possible explanation:
*Organisms descended from species that colonized the islands
*Usually from nearby continents
*Long-distance dispersal
*Once there, they adapted to predator-free environment
ADAPTIVE RADIATION
what is adaptive radiation?
Adaptive radiation is a process in evolutionary biology where a single ancestral species rapidly diversify into a wide variety of descendant species, each adapted to occupy different ecological niches or environments. This phenomenon often occurs when a group of organisms encounters new, diverse habitats with numerous unexploited ecological opportunities. Adaptive radiation leads to the emergence of multiple new species, each specialized to exploit a specific niche within their environment.
what proves evolution?
If we take into consideration proofs from Anatomy, Fossils, Natural history, Embryology and Biogeography, we can see how evolution has shapes the organisms we see today
