Evolution
What is adaptation?
A trait that helps an organism survive and reproduce
morphological species concept
characterizes a species by body shape and other structural features
Earth's early atmosphere did not contain what?
oxygen
biological evolution
the change over time in populations of related organisms and their traits
sex
the biological distinction between females and males
Multicellular organisms
an organism that is made up of many cells
stabilizing selection
form of natural selection in which individuals near the center of a distribution curve have higher fitness than individuals at either end of the curve
geographic isolation
isolation between populations due to physical barriers
What can cause mutations?
- missed repairs - UV radiation/chemicals
Evidence of Evolution
1) Fossil Record 2) Embryology 3) Homologous Structures 4) DNA 5) Vestigial Structures
Rates of Speciation
1. Gradualism 2. Punctuated Equilibrium
DNA
A complex molecule containing the genetic information that makes up the chromosomes.
radioactive dating
A technique used to determine the actual age of a fossil on the basis of the amount of a radioactive element it contains
What is melanin?
A protein pigment found in epidermal cells, protect skin against radiation from the sun.
what is the difference between evolution and Biological evolution
Biological evolution is change of traits over time and evolution Is change over time not traits.
How has racial classification been used in North America?
By races; In North America, people usually think in terms of Black, White, Asian, Hispanic or Latino, and Indian or Native American.
Evolution
Change over time
Based on the risk factors discussed in the film, which of the following groups should consider taking vitamin D supplements to avoid rickets?
Children born to parents with dark skin living far from the equator.
fossil record
Chronological collection of life's remains in sedimentary rock layers
Besides genetics, what other factors can affect a person's appearance and growth?
Environment influencers
What is macroevolution?
Evolutionary changes that result in the formation of new species.
What is speciation?
Formation of new species
What two main factors is evolution dependent on?
Genetic mutations and natural selection
How does natural selection lead to evolution?
Helpful traits accumulate among surviving members of the species.
What is fitness, evolutionarily speaking?
How good a genotype can produce offspring
variation in human skin color
Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin. Also, The variation in human skin color correlates with the intensity of UV radiation around the world.
spontaneous generation
Hypothesis stating that life could arise from nonliving matter.
list 3 sources of genetic variation
Mutations, gene flow, and sex
directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
examples of instances in which evolution has been observed
New species developing, and diseases
What are examples of sexual selection?
Peacock feathers, dances, gifts
Co-evolution
Process by which two species evolve in response to changes in each other
convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
Pasteur's experiment
Published results of his experiment. Placed sterilized broth in a sterilized flask. He clearly showed that bacteria couldn't arise spontaneously. Only when open to air, the bacteria could emerge.
reproductive isolation
Separation of species or populations so that they cannot interbreed and produce fertile offspring
What are some traits that people share?
Skin and hair color, facial characteristics, body shape, and stature.
What evidence supports the vitamin D hypothesis for the evolution of lighter skin tones?
Some indigenous peoples living at high latitudes have darker skin, but they tend to eat foods rich in vitamin D.
biological species concept
Species is a group of populations whose members have the potential to produce fertile offspring.
Evolution in natural communities arises from both constraints and opportunities. What are the constraints?
The constraints come from competitors, primary among the same species
Darker skin is more prevalent in high-UV areas. Dr. Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. On what evidence did she base this hypothesis?
The larger amount of brown-black melanin in darkly pigmented skin protects circulating folate from being destroyed by UV radiation.
Why isn't skin color a good way to classify people?
They are essentially labels of ethnicity that are used for categorizing and discriminating.
What are transitional forms?
They are forms of species intermediate between the orginal form and the current form.
Why do sub-Saharan Africans have the same dark skin color as many people in places like southern Asia and Australia?
They continue well outside of the geographic areas in which a "race" is stereotypically supposed to exist.
How does melanin affect the color of the skin?
UV exposure darkens existing melanin and stimulates melanocytes. When melanocytes are stimulated, melanin is transferred from the melanocytes to keratinocytes in the stratum Basale.
Examples of homologies
Wing of bird, flipper of dolphin
What is a species?
a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
molecular species concept
a group of organisms are classified in the same species if they appear identical in DNA sequences
Theroy
a logical explanation for events that occur in nature
Melanocytes
a mature melanin-forming cell, typically in the skin.
examples of vestigial structures
appendix, tailbone, wisdom teeth, 3rd eyelid
In which of the following areas of the globe would you expect to find relatively high amounts of UV radiation?
areas at high elevation and areas at a latitude near the equator.
Isolating mechanisms
barriers to imitation that prevent rivals from competing away the advantage a firm may enjoy
limitations of biological species concept
cannot be applied to fossils or asexual organisms, emphasizes absence of gene flow
Pheomelanin
causes the reddish browns of freckles and red hair.
Mutation
change in a DNA sequence that affects genetic information
What is the relationship between Humans and Apes?
common ancestors
Are dark-skinned people at an advantage or disadvantage in northern latitudes?
disadvantage because there is not enough vitamin D
descent with modification
each living species has descended, with changes, from other species over time
divergent evolution
evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions
What is microevolution?
evolutionary change within a species or small group of organisms, especially over a short period.
limitations of biological species concept
extinct organisms and organisms that don't reproduce sexually
Causes of speciation
geographic isolation, reduction of gene flow, reproductive isolation
Eumelanin
gives rise to a range of brown skin tones, as well as black, brown, and blond hair, and pheomelanin.
UV light
invisible light that lies beyond violet. Has higher energy and shorter wavelengths than visible light does.
how does melanin respond to ultraviolet radiation?
it reacts less than 1 out of every 1000 times it becomes excited. This allows melanin to protect more sensitive molecules, like DNA, from UV exposure.
gene flow
movement of alleles from one population to another
disruptive selection
natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve
Did Darwin recant evolution on his deathbed?
no
Did humans evolve from apes?
no
do maggots' appear out of nothing?
no
Prokaryote cell
no nucleus, no organelles, DNA floating around, genetic material, cell membrane, cytoplasm, simple
Homologies
phenotypic and genetic similarities due to shared ancestry
What is coevolution?
process in which two or more species evolve in response to changes in each other
what were most likely the first type of cells?
prokaryotes
vestigial structures
remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.
How does selection actually work?
selection can only work on genetic variation that already present in any new generation, and genetic variation occurs randomly, not in the response to the needs of the population or organism
What is artificial selection?
selective breeding of plants and animals to promote the occurrence of desirable traits in offspring
homologous structures
similar structures that related species have inherited from a common ancestor
Law
something backed up by a mathematical statement
Embryology
study of embryos and their development
Besides melanoma, what other conditions does melanin shield against?
sunburn damage and damage to DNA
Modification by Natural Selection
the idea that the environment selects individuals best suited to live there for survival
Epigenetics
the study of environmental influences on gene expression that occur without a DNA change
how does light interacts with the pigments in a red tomato?
the pigments reflect red light
how does epigenetics apply to evolution?
the quality of life directly affects how our genes operate. diseases can have started all the way back into you ancestry. it's not just a health problem but a much broader social equity issue.
natrual selection
the theory that organisms better suited to their environment are more likely to survive
sexual selection
when individuals select mates based on heritable traits