Chapter 11 Flashcards
Theory of evolution
States that living things present on earth today are the diverse descendants of a single common ancestor
Natural selection
Advantageous traits are inherited that allow some individuals to adapt better to an environment making them survive and reproduce better than others
When would natural selection take place?
More offspring are produced than environment can support
Competition for limited resources/ mates
Why is genetic variation so important for natural selection?
Genetic variation allows some offspring to survive and reproduce better than others
Adapt better
What is responsible for selecting the most successful individuals in a population: the environment or the organisms themselves?
The environment
Micro evolution
Ex?
Changes that occur in the characteristics of a population (within one species)
Occurs quickly, results in changes of allele frequencies
Ex: skin pigmentation
Macro evolution
Ex?
The changes that give rise to new species
Over long periods of time
Product of many micro evolutionary events
Ex:elephant family tree (phylogeny)
Following the introduction of a new pesticide, a population of tomato hornworms evolves resistance to the pesticide over the course of 50 generations?
Micro or macro ?
Micro evolution
Birds and crocodiles share a common ancestor with dinosaurs.
Micro or macro?
Macro evolution
Adaptation
An inherited trait that increases the likelihood of survival and reproduction in a particular environment
Mutation
A heritable change in the DNA sequence of a gene
Change in amino acid can result in a new protein or messed up protein
Ultimate source of variation
Gene flow
The movement of individuals into or out of a population
Immigration: adds alleles; increases variation
Emigration: removes alleles; decreases variation
Genetic drift
Random change in allele frequencies in SMALL populations due to chance that may result in the loss of genetic variation an
Which results in the evolution of new species from a common ancestor?
Adaptive radiation
Macro evolution
Which is considered reliable evidence of evolution?
Fossils
Homologous chromosomes
Geographic distribution
DNA similarity
Artificial selection
Observation/testing
The wing of a bird and the wind of an insect are considered ____ structures?
Analogous
Can mutations result in micro evolution?
Yes, change in amino acids produce new proteins in the same species
Population Bottleneck
A dramatic reduction in population size that leads to a change in allele frequencies and possibly the loss of alleles (loss of variation)
Ex: Famine, hunting, plague, catastrophic events
Founder effect
A small group establishes a “founder population “ that is isolated from the original population
Chance matings can result in changes in allele frequencies
Ex: Amish with 6 fingers
Fossils
Preserved remains of once living organisms
Ex: imprint, amber, or bone fossils
Anatomical similarity (homologous structures)
Structures that look similar in appearance (anatomy) and function because they are inherited from a common ancestor
Ex: ears; feathers; forelimbs; bone arrangement in skeleton
Geographic distribution
Species that live in neighboring regions are more likely to share a common ancestor
Ex: euphoria plants found in S. America, S. Africa Australia
Molecular Homologies (DNA similarities )
If DNA sequence are very similar this is almost likely because they are inherited from a common ancestor
Speciation
The evolution of a new species or multiple new species from an ancestral species
Species
A group of individuals that are capable of interbreeding and producing fertile offspring
Allopathic speciation
The formation of new species through geographic separation
No gene flow, so reinforced by reproductive isolation
No chance of mixing
Sympatric speciation
The formation of new species without geographic separation
Utilizing different parts of the habitat
Same area
Adaptive radiation
Results in a single ancestor evolving into several different species
Ex: Darwin’s finches; Hawaiian honey creepers
Wings of a bird and the wings of bees homologous structures?
No, they are analogous structures because even though they have the same function they did not evolve from the same common ancestor
Scientific theory
A powerful, broad explanation of a large set of observations
- based on many hypotheses
- well supported by evidence
Evolution
A change in the genetic traits (allele frequencies) of a population of organisms over many generations
What evolves populations or individuals ?
Populations
Was Darwin the first person to come up with the idea of evolution?
No, but Darwin was the first to explain a logical, testable method to explain HOW species change over time …. that natural selection causes evolution
Evolutionary adaptation
A heritable trait or behavior in an organism that aids in its survival in its present environment
Population
All the individuals of the same species living in the same area
Natural selection is considered the primary cause of _______, and the only cause of _________
Evolution; adaptive evolution
How does natural selection work? What are the series of observations?
1) individuals within populations vary
Ex: appearance, enzyme structure
2)some of the variation is inheritable
3) populations of organism produce more offspring than will survive
Ex: Rabbits
4)those with traits that best enable survival and reproduction have more offspring
Differential reproductive success =?
Natural selection
Fitness
Relative survival and reproduction (a good fit for that environment)
Divergent evolution
An evolution that results in different forms in two species with a common ancestor
Convergent evolution
An evolution that results in similar forms on different species
How are people contributing to Antibiotic resistance ?
Doctors over-prescribing antibiotics
Patients misusing antibiotics (failure to follow treatment)
Heavy use of antibiotics in livestock
Natural selection does not cause new traits to arise because they need to! It only acts on genetic variation that already exist
True or false
True
Antibiotic resistance
The ability to be unaffected by antibiotics
Artificial selection
Selection imposed by human choice
Ex: breeds of dogs , agricultural crops
Direct testing/ observation
Environmental conditions can be manipulated and effects of population examined
Ex: antibiotic resistance, Galapagos finches after a drought
Developmental homologies
Shared developmental pathways
Ex: chordate embryos
Analogous structures
Similarity in characteristic as a result of adaptations to similar environment, not because of common ancestry
Biography
Study of geographic distribution of organisms on Earth
Unity of life ?
Many characteristics are shared by very, different organisms because had a common ancestor
Diversity of life?
Divergence from common ancestor
Which mechanism results in adaptive evolution ?
Natural selection
