college bio natural selection test

basic beliefs of the pre-darwinian world on where life originated?

1. earth is young-up to 10,00 years old

2. specially created organisms-fixed species “fixity of species”

3. adaptations are specifically designed

4. observations support beliefs-natural theology

Plato & Aristotle

• every object on earth is a copy (imperfect) of an ideal form

• individual variation gives proof of the imperfections of life

• opposed to concept of evolutionary change

Georges cuvier

• founded the science of paleontology

• he knew much about comparative anatomy and studied fossils

• staunch supporter of fixity of species

• catastrophism: belief that earth is young and that fossils and land formations are the result of natural catastrophes

Georges-Louis Leclerc

-french naturalist

-wrote 44 volume of natural history

-Descent with modification: he believed that a species could change over time, but would remain the same species

this modification was due to the following features:

1. direct influence of environment within which the species lives

2. migration of species from one environment to the next

3. geographic isolation: species that are restricted by geography will become different than species in another environment

4. pressure from overcrowding and the struggle to survive may influence the traits of the survivors within the population

• did not claim natural selection

charles Lyell

geologist who wrote one of the first modern geology works called principles of geology

• earth’s geology is slow to change-most change is due to the slow processes of uplift and erosion

• exposed rocks weather and sediment is deposited at the bottom of ponds to form future sedimentary rocks

• uniformitarianism: concept that the rock cycle will proceed at a gradual and constant rate

Jean Baptiste Lamarck

• believed that evolution/speciation does occur by the inheritance of acquired characteristics

• he proposed that organisms can attain adaptations to their traits throughout their lifetime

• he thought that a natural life force existed within all living creatures, this allowed them to become better adapted to their environment

• concept of use and disuse: if an organism uses a trait it will become more developed over time. If a trait is not being used it will not develope or be less prominent.

• ex)giraffes neck

Linnaeus

• father of taxonomy

• he described what he thought was the proper place for each species-this he referred to as scala naturae, the sequential ladder of life

• he did believe in fixity of species- concept that every organism was specifically created by God and its traits, both physical and behavioral, remain fixed.

Alfred Wallace

• publishes origin of species in 1859

• he independently made the same conclusions as Darwin, but gave him the heads up, allowing Darwin to publish a book on the subject. The two did jointly publish a paper

animal husbandry

• selective breeding/ artificial selection

• corrosive to the concept of fixity of species-

• ex) dogs: dalmatian v poodle

darwin’s studies and conclusions

• he sailed on the trading ship, HMS beagle from 1831-1836 as the ship naturalist

• he went from England down the eastern coast of south America and up the western coast

• he observed geological diversity, fossils, biogeography

• he concluded that living organisms are descended from extinct animals-this concept challenges fixity of species

• he also concluded that animals share a common ancestor, but had become adapted to life on the different Galapagos islands

Modern lines of evidence

biogeography, fossils, embryology, molecular biology (gene homology), and comparative anatomy

biogeography

The distribution of animals and plants does vary on different continents

fossils

Fossils are preserved evidence of prehistoric life—typically over 10,000 years old—including body parts (bones, shells, teeth) and traces (footprints, burrows, feces).

They provide data on evolutionary history, ancient ecosystems, climate change, and geological dating, acting as physical evidence of Earth's biological history.

embryology

Embryology studies the formation, growth, and development of organisms from fertilization through the embryonic stage. It includes data on gamete maturation, fertilization, cleavage, blastocyst formation, implantation, and early organogenesis. It focuses on cellular differentiation, genetic control of development, and morphogenesis, which shapes organs

molecular biology (gene homolgy)

Molecular biology (gene homology) includes data on DNA, RNA, and protein sequences that share a common ancestor, used to determine evolutionary relationships and functional similarities. Key information includes sequence alignment, conserved amino acids, orthologs (speciation-based), paralogs (duplication-based), and structural homology.

comparative anatomy

Comparative anatomy is the study of similarities and differences in the structures (bones, organs, muscles) of different species to understand evolutionary relationships. It focuses on homologous structures indicating shared ancestry, analogous structures from convergent evolution, and vestigial structures, providing evidence for evolution and supporting fields like paleontology and taxonomy

Tenets of theory of natural selection

relies on four main tenets:

1. variation in traits among individuals

2. inheritance of these traits

3. overproduction causing a struggle for existence

4. differential survival/reproduction based on beneficial traits.

industrial melanism as an example of microevolution

Industrial melanism is a classic example of microevolution, where rapid changes in allele frequencies within a population occur due to natural selection in response to environmental changes. During the Industrial Revolution, pollution prompted a shift in peppered moth populations from light-colored to dark-colored, improving survival against predators on soot-stained, lichen-free tree bark.

microevolution

Microevolution is the small-scale change in allele frequencies (gene variants) within a population over a short period, typically generation to generation.

types of selection that act on specific traits (microevolution

disruptive, stabilizing, and directional selection

directional selection

when one of the classes of phenotypes is favored over time the distribution will shift in the direction of the preferred phenotype

ex)size in horses

stabilizing selection

when the intermediate phenotype is preferred, the number of individuals in the population with the trait will increase

both extremes are unfavorable, making the trait appear more homogenous over time(middle trait is favored)

this appears less diverse

ex) human birth weight

disruptive selection

occurs when 2 extreme phenotypes are favored over the intermediate-organisms live in different environments

ex) white snails are favored in low vegetation environment while black snails are favored in high vegetation environment-over time you see black and white snails but not the grey intermediate

modes of speciation

allopatric, sympatric, parapatric/peripatric

allopatric speciation

typical/common speciation

speciation dur to a barrier like:

-geographical: mountain range or body of water

-ecological: second species compete with the organism, making it harder for the original organism to eke out existence

*know a scenario

sympatric speciation

speciation that occurs when 2 populations live around each other

here the 2 populations ranges will overlap, but the 2 populations still won’t interbreed

they develop to some aspect of their range

there is no geographical isolation

*Know a scenario

nondisjunction

occurs resulting in polyploidy (plant will have an extra complete set of chromosomes) so the chromosome number has increased to 3 copies

• a rare genetic abnormality (polyploidy)

• Egg: 2n (result of nondisjunction) + sperm 1n=3n

• doesn’t occur in animals

adaptive radiation

rapid development of several species from one ancestor

punctuated equilibrium

an evolutionary theory proposing that species experience long periods of stability (stasis) interrupted by brief, rapid bursts of change and speciation.

it explains the "sudden" appearance of new species and lack of intermediate fossils, suggesting evolution occurs in fast spurts rather than constant gradual changes.

gradualism

the theory that species evolve slowly, consistently, and continuously over long periods, rather than through sudden, drastic changes.

Proposed by Charles Darwin, this model suggests that small, genetic and morphological variations accumulate over time, eventually leading to the formation of new species