Evolution by Natural Selection : Biology Flashcards
Evolution
The change in allele frequencies in a population from generation to generation.
Does evolution always refer to one species evolving into another species?
Evolution DOES NOT always lead to more advanced species.
How does evolution works at the population level?
Some individuals in population are better able to survive and many of these individuals mate resulting in offspring with greater survival and advantageous traits.
Why evolution is considered a fact of nature?
There is a wealth of evidence that supports it and there are no other competing theories or hypotheses that can explain how populations (and species) change over time.
How does evolution shape biodiversity?
Organisms will continue to adapt. The diversity of environment that exists promote a diversity of organisms which adapt to them.
How does the USA view evolution relative to other westernized countries. How does this pattern of acceptance varying within our country?
The US is one of the few where controversy around the topic still exists. It appears 50/50 on the chart. Coming in at less than 50 is Mississippi.
What are the 4 categories of Empirical Evidence for Evolution?
Either the 3 levels of homology or anatomy, molecular biology, biogeography, fossils, & direct observation (steps to conclusion)
What are the 3 levels of homology?
- Developmental Homology
- Structural Homology
- Genetic Homology
Developmental Homology = embryo, eyes
Similarity in embryonic form or developmental processes due to inheritance from a common ancestor. (The early embryonic stages of a human, chick and cat show strong resemblance/developmental processes)
Structural Homology = bones, brains
Similarity in adult organismal structures due to inheritance from a common ancestor. Even though the function varies, all vertebrate limbs are modifications of the same number. (Between humans, horses, birds, bats and seals; along with brains of humans, fish, birds, 98% chimps, and 90% cats.)
Genetic Homology = DNA
Similarity in DNA, RNA, or amino acid sequences due to inheritance from a common ancestor. (A human and fruit fly amino acid sequence is very similar. 99.7% Neanderthal (old human) 98% Chimp 92% Mouse)
Why are there biases in the fossil record? Know processes that lead to this bias.
- fossils often fragmented
- bones, teeth and shells more abundant than tissue, organs
- Paleontologists tend to focus on best fossil-bearing rocks already discovered
- an organism has to die in right place at right time under good condition, well preserved
Endemic Species
Species specific to particular location, found nowhere else. Often higher risk of extinction, unique evolutionary histories.
How does endemic species help us understand relatedness?
Geography better predictor of relatedness than habitat. (Pangea)
When and where did Darwin’s Beagle voyage take place?
- In 1831-1836
- His mission was to explore the South America coastline because Europeans didn’t know much about it. During his voyage he spent more time studying the animals and specimens on shore, especially the Galapagos.
- Southern Australia, South Africa, West of Europe, East, South and West of South America
- he travelled to these places again with Russel Wallace
What did Darwin find at the Galapagos?
Tortoises:
- In the highlands, domed shell
- In the lowlands, saddle-shaped shell
Finches:
- large, ground finch, heavy beak, eat seeds
- Warbler finch, thin beak, eat insects
- Cactus finch, curved beak, split tongue, eat cactus flower nectar
What is the name and publication date of his most famous book? And his two proposed hypothesis?
A new era of biology began on 24 November 1859 when Charles Darwin published On the Origin of Species. Organisms have descended with modification from common ancestors = evolution and cause of descent with modification is natural selection.
What other influential scientists and the role they played in contributing to Darwin’s theory of evolution by natural selection?
Thomas Paine, Mendel, Alfred Russel Wallace (voyage)
The order in which natural selection takes place according to Darwin. !
- Individuals in a population vary in their heritable characteristics. / Organisms produce more offspring than the environment can support.
- Individuals that are well suited to their environment tend to leave more offspring than other individuals.
- Over time, favorable traits accumulate in the population.
What are the 3 words that best define evolution by natural selection?
‘Differential Reproductive Success’
Postulates of natural selection. !
1 Individuals in a pop are variable in phenotype
2. Some phenotype differences are heritable
3. Species produce more offspring than environment can support (competition)
4. B/c individuals are unique, some have attributes that allow them to exploit resources more efficiently than others (favorable adaptations)
5. These individuals more likely to survive and leave offspring (differential reproductive success)
6. The frequency of traits that confer an advantage will gradually increase over generations
Why does selection act on the individual, but it is the population that evolves?
Individuals may mutate, but natural selection acts by shifting the characteristics of the population as a whole.
How are peppered moths, camouflage, mimicry, and lactose tolerance are all examples of natural
selection?
- Polluting smog and soot from fossil fuels, the pepper moth adapted to match the tree due to it changing color from being covered in soot. So, the black moths were eaten the most because they stood out.
- Mimicry occurs from the Viceroy butterfly resembling the Monarch butterfly which is poisonous result in less eating of Viceroy.
- When born enzyme called lactase that the body produces to break down lactose.
By default everyone should be lactose intolerant, but someone’s didn’t shut off so they had the ability to ingest milk so now more people can tolerate it. Recessive mutation allows lactase production to continue on into adulthood.
Co-evolutionary race. How can natural selection cause this?
Predators have evolved specialized weapons of attack and prey have evolved specialized defenses. Individuals with the best survival traits face each other in the end.
