2. Descent with Modification (Evolution) Flashcards
What is Adaptation?
a heritable trait that increases the survival and reproduction of an individual in a particular environment compared to individuals without that trait
What were Darwins’ Two Main Ideas?
- Descent with modification (or evolution) explains life’s unity and diversity
- Natural selection is a cause of adaptive evolution
What were Darwins’ Two Main Ideas?
- Descent with modification (or evolution) explains life’s unity and diversity
- Natural selection is a cause of adaptive evolution
What are the 3 Types of adaptations that exist to enable species to survive?
- Structural (Physical Features)
- Behavioural (Learned or Inherited Actions)
- Physiological (Internal and Cellular Processes)
What are some examples of Structural Adaptations? (4)
Ex. 1- Penguins have blubber to protect themselves from freezing temperatures
Ex. 2 - Carnivores have sharp canines to kill and tear meat
Ex. 3 - Giraffes have long necks that allow them to browse leaves off the tops of grassland trees, helping them avoid food competition from other herbivores
Ex. 4 - Chameleons use camouflage to evade a predator
What are some examples of Behavioral Adaptations? (4)
Ex. 1 - Bears hibernate in winter to escape cold
temperatures and preserve energy
Ex. 2 - Porcupines curl up into a ball when threatened
Ex. 3 - Fish swim in schools for protection
Ex. 4 Geese fly south in the fall to allow them to stay warm and find food during winter
What are some examples of Physiological Adaptations? (2)
Ex. 1 -Snakes produce poisonous venom to ward off predators and capture prey
Ex. 2 - Pesticide and antibiotic resistance
What 5 Observations Did Darwin Make?
OBSERVATION #1:
For any species, population sizes would increase exponentially
OBSERVATION #2:
Populations tend to be stable in size
OBSERVATION #3:
Resources are limited
OBSERVATION #4:
Members of a population vary extensively in their characteristics
OBSERVATION #5:
Much of this variation is heritable
What 3 Inferences Did Darwin Make?
INFERENCE #1:
Production of more individuals than the environment can support leads to a struggle for existence
INFERENCE #2:
Survival depends in part on inherited traits.
Individuals with traits that give a high probability of surviving and reproducing are likely to leave more offspring
INFERENCE #3:
This unequal ability of individuals to survive and
reproduce will lead to a gradual change in a population, with favourable characteristics being more common
Evolution by natural selection occurs when…
(2)
- heritable phenotypic variation in the population leads to ….
- differential reproductive success - the unequal ability of individuals to survive and reproduce
What is a Phenotype?
– phenotype refers to an organism’s observable characteristics or traits, including its
(i) physical form and structure,
(ii) developmental properties,
(iii) biochemical and physiological properties, as well as
(iv) behaviour
What is Biological Fitness?
(3)
the ability of an individual:
1. to survive to reproductive age,
2. find a mate,
3. produce live, fertile offspring
(relative to that ability in other individuals in the population)
What does natural selection NOT do? (2)
Natural selection DOES NOT create new traits, but edits or selects traits already present in a population
Note, that individuals DO NOT evolve; populations evolve over time
What is Artificial Selection?
(4)
The offspring of each generation vary (the differences may be so small that only trained breeders can detect them)
– Those that are more like what the breeder wants are selected for further breeding; the rest aren’t allowed to breed
– This is repeated
– Eventually, the small differences add up to a large change in the breed
What is a Fossil?
A fossil is the preserved remains or traces of an organism that lived in the past
What are the 6 most often cited types of fossils?
(MCCPTT)
- Molds
- Casts
- Permineralized Fossils,
- Carbon film (compression) fossils,
- Trace fossils
- True-form (intact) fossils
What is a Mold?
A mold is formed when an organism decays completely but leaves behind a hollow physical impression of itself
What is a Cast?
A cast forms when minerals and sediment deposit into a mold and hardens over time, resulting in a three-dimensional physical replica of the hard structures of the organism
What is a Permineralized Fossils?
Permineralized fossils form as organisms decompose slowly, which allows dissolved minerals to gradually infiltrate the interior of cells and harden into stone
What is True-Form Fossils?
True-form fossils preserve the entire natural form of the organism
Include entrapment of organisms in amber/ice/tar, as well as mummification
– Soft issues remain entirely intact
What are Carbon film fossils?
- Carbon film fossils are formed from the carbon residue of the soft-bodied organism that has been buried in sediment
– Eventually, all materials that make up the body of a dead organism break down from heat and immense weight of overlying layers of sediment, leaving nothing but a thin film or residue of carbon (forms shape of body outline)
– Usually black, dark brown or light brown in colour, depending on the type of rock they are pressed upon
What are Trace Fossils?
Trace fossils provide indirect evidence of life
– Show evidence of organism activity
– Include footprints/trackways, tooth marks, coprolites (fossilized feces), burrows,
nests and gastroliths (small stones swallowed by a bird, reptile, or fish, to aid in
digestion by breaking up food)
What is Habitat Bias?
- Organisms that live where sediment is actively being deposited (e.g., beaches, mudflats, swamps) are more likely to fossilize than are organisms in other habitats
- In these habitats, burrowing organisms are more likely to fossilized compared to organisms living above ground
What is Taxonomic and Tissue bias?
- Some organisms (e.g., those with hard parts such as bones or shells) are more likely to decay slowly and leave fossil evidence compared to soft-bodied organisms
- Tissues with a tough outer coat that resists
decay (e.g., pollen) fossilize more readily
What is Temporal bias?
- More recent fossils are more common than ancient fossils
- Older fossils usually occur in sedimentary rock layers deep below newer layers
- These fossils are vulnerable to crushing, heating, melting, and distortion by various chemical and physical processes
- Also, older fossils are more likely to be pushed further into the Earth’s interior by the sliding and collision of tectonic plates
What is Abundance Bias?
Organisms that are abundant, widespread, and present for a long time leave evidence much more often than do species that are rare, local, or ephemeral (lasting for a very short time)
What are Homologous Structures?
(Homology)
- homologous structures are body parts that share a common ancestor, but may not necessarily perform the same function
Example:
– Forelimb bones in a human arm, horse leg, seal flipper and bat/bird wing
What is Divergent Evolution?
a process in which a trait held by a common ancestor evolves into different variations over time
What are Analogous Structures?
(Homoplasy)
What are some examples?
body parts that perform the same function, but have a different evolutionary history
(so the similarity in function NOT resulting from common ancestry)
Examples:
– Walking limbs of insects and vertebrates
– Wings of birds and bats look similar in the structure though they evolved independently
– Cranium of vertebrates and exoskeleton head of insects
– Eye of octopus and eyes in humans
– Arctic fox and ptarmigan (a bird) both under seasonal changes of colour from dark to snowy white
What is Convergent evolution?
Convergent evolution is the process in which species that are not closely related to each other independently evolve similar kinds of traits
True or False:
Forelimb bones of humans, dogs, birds and whales represent homologous structures, which were developed through convergent evolution.
False
Forelimb bones of humans, dogs, birds and whales represent homologous structures, which were developed through DIVERGENT evolution.
D. population
Analogous Structures
Homologous Structures
