Introduction and Evolution Flashcards
Comparative vertebrate anatomy [Definition]
study of functional morphology of vertebrates
Comparative vertebrate anatomy [Points]
- compares body form and function of various structures
- compares similarities and differences in morphology
- interprets similarities and differences in ancestry, function, and evolution
Why study vertebrate morphology?
- learn and understand morphology
- advance human knowledge
- understand relationship between form and function
- to study evolution
- fascinating
What is science?
- a way of knowing
2. a method of collecting information
What are other ways of knowing?
- faith
- experience
- experience of others
What is faith?
- a confident belief in the truth, value, or trustworthiness in a person, idea or thing
- that belief does not rest upon logical or scientific proof or material evidence
What is experience?
active participation in events or activities leading to the accumulation of knowledge and skill
Steps in the scientific method
- identification of a problem, ask a question
- defining the entity to be studied
- designing an experiment/ study
- obtaining a representative sample
- collect data by observing and measuring samples
- analyze data
- interprete data/ draw conclusions
- report methods
Weaker methods of studies?
- correlation
- comparative studies
- historical studies
- modeling
What is evolution?
- changes in gene frequency of a population through time
2. changes in character states of organisms through time
Evolution requires:
- genetic variability
2. differences in ability to survive and reproduce being linked to differences in heritable genetic variation
What is genetic variability?
ultimate source of variation is mutation
What is natural selection?
differential reproduction and survival of organisms with certain character states or genotypes. Not survival of the fittest.
How does natural selection work?
- more offspring is produce than can survive each generation
- population size exceeds the environments carrying capacity
- critical resources becomes limited
- competition occurs
- additive genetic variation in competitive ability exists
- best competitors survive and reproduce
- they are more fit
- fitness–relative number of offspring produced
- results in an increase in a frequency of the traits that increased fitness in the next generation
- if frequency of a given character state changes
- currenect generation—-natural selection
- next generation—-evolution
Example of evolution by natural selection
- Poecilia reticulata—-common guppy
- live in Trinidad
- female prefer males with lots of coloration and high display rates
- populations occur in high and low predation habitats
i. high predation
a. males have reduced coloration and display behavior
b. natural selection is stronger than sexual selection
ii. low predation
a. males are brightly colored and have high display rates
b. sexual selection is stronger than natural - fish from high predation habitats were transferred to low predation habitats
- fish from low predation habitats were transferred to high predation habitats
- populations were assayed for their coloration and display behavior 3 years later about 9 to 12 generations
- low predatation guppies had lost most of its color and had reduced display rates
- high predatation guppies had increased in color and had increased display rates
- populations bred true in lab
Evolution by Natural Selection
- adaptation is a process of a population becoming adjusted to a particular environment over many generations
- adaptive trait is a structure, a physiological mechanism, or behavior that increases the probability that an organism will survive to reproduce
- adaptive traits are not always inherited
- habitat dependent and will be for the current environment
- natural selection doesn’t evolve toward some predetermined goal
- genetic variability must exist
- individuals with certain gene combinations will be more fit [co-adaptive gene complex]
- different gene combinations may have the same fitness
- adaptations are not perfect vertebrate eye
Kinds of selection
- Natural selection
- artificial selection
- sexual selection
natural selection
differential survival of genotypes/phenotypes
artificial selection
differential breeding of organisms with certain desirable traits by humans
sexual selection
differential mating success
1. male male competition: structures that help males uptain resources/win fights 2. female choice
forms of selection
- directional selection
- stabilizing selection
- disruptive selection
directional selection
- selects for an extreme phenotype at one end of the distribution
- causes the traits distribution to shift
- mean, median , mode all change
- standard deviation may increase, decrease, or remain the same
stabilizing selection
- tends to eliminate individuals at each end of the distribution
- selects for a mean value of a trait
- mean, median, mode are stationary
- standard deviation decreases
- adapted to local conditions and prevents change
disruptive selection
- eliminates individuals with the mean character state
- selects for the two extreme forms
- mean may remain the same
- bimodal
- standard deviation increases
- assortative mating: one phenotype prefers to mate with that phenotype
- speciation arises: splitting of one species to more