Chapter 1 Flashcards
Define Zoology
Scientific study of animal life
What are the major characteristics of animals
Multi cellularity, coelom, spiral cleavage, vertebrae homethermy
What are the essential characteristics of science
- science is guided by law
- science has to be explained by reference to natural law
- science is testable against the observable world
- the conclusions of science are tentative
- science is falsifiable
What are the components of the science method?
Observation Question Hypothesis Empirical Test Conclusions Publications
How is the term theory used differently in science?
In everyday, theory means speculation in science it means explanation of nature or predictions ( observation)
How are comparative methods different from experimental methods?
In comparative you investigate where as experimental method has three steps
- predicting
- make treatment
- compare results
Who were some of the earliest contributors to evolutionary thought?
Charles Darwin , Alfred Wallace
–Early Greek philosophers Xenophanes, Empedocles, and Aristotle
How does Darwins Theory of of natural selection work?
Variation. Organisms (within populations) exhibit individual variation in appearance and behavior. …
Inheritance. Some traits are consistently passed on from parent to offspring. …
High rate of population growth. …
Differential survival and reproduction.
Define Gene
segment of DNA that makes a protein which affects a certain trait
Define Allele
Gene Variant
Define Dominant
expressed trait whenever at least one copy of allele is present
Define recessive
expressed trait only when both copies are present
Define homozygous
possessing two identical alleles
Define Heterzygous
possessing different alleles
Define genotype
allelic combination for a trait
Define phenotype
expressed trait, what is seen
What is a gene pool
All alleles of all genes that exist in a population
How are genotype frequencies calculated?
by expanding the binomial (p - q)2 where p and q are allele frequencies for the dominant (p) and recessive traits (q)
•p2 + 2pq + q2 = 1
What is Hardy-Weinberg Equilibrium (HWE)?
–Genotypic frequencies remain in balance unless disturbed
–Allows for rare traits caused by recessive alleles to persist
–In natural populations, Hardy-Weinberg equilibrium is disturbed by 1 or more of 5 factors
•Mutation
•Genetic Drift
•Nonrandom Mating
•Migration
•Natural Selection
Describe how HWE is upset by the following process:
Mutation
–Introduces new alleles, increasing genetic diversity
–Only a small change in allele frequency
Describe how HWE is upset by the following process:
Genetic Drift
Chance fluctuation from generation to generation, including loss of alleles
–The smaller the population, the greater the effect of drift
–Bottlenecks
•Large reduction in population size leading to increased significance of genetic drift
Describe how HWE is upset by the following process:
Non random mating
Mating that has not occurred due to chance
–Courtship displays, territories, pecking order, etc.
–Can lead to a host of phenotypes that should be selected against
Describe how HWE is upset by the following process:
Migration
Prevents different populations from diverging
–If a large species is divided into many small populations
•Genetic drift and selection acting separately in the different populations can produce evolutionary divergence among them
•Small amount of migration each generation prevents the different populations from becoming too distinct genetically
Describe how HWE is upset by the following process:
Natural Selection
–Stabilizing selection •Selects against extreme phenotypes –Directional selection •Phenotypic character shifts in one direction –Disruptive selection •Selects against average phenotypes
What are the two possible fates of a species?
Extinction (loss of all populations)
–Speciation (splitting of populations into new forms)
What is a mass extinction?
–Periodic events where huge numbers of taxa go extinct
