General Ecology Chapter 2 Flashcards
What is the Malthusian theory of population?
Earth was not overrun by humans, population growth must be limited by food shortage, disease, war, or conscious control
What is natural selection?
Better-adapted organisms would acquire more resources and leave more offspring
What is adaptation?
Given an evolutionary time span, a population’s characteristics change to make its members better suited to their environment
What are characters?
many readily available varieties that differed in visible characteristics
What is self-fertilization?
makes it easy to produce plants that breed true for a given trait meaning that the trait does not vary from generation to generation
What is a true-breeding line?
A variety that continues to exhibit the same trait after several generations of self-fertilization
What is cross-fertilization or hybridization?
When two individuals with different characteristics are mated or crossed to each other and the offspring are referred to as hybrids
What is the P generation?
The true-breeding parents
What is the F1 generation?
The first generation offspring of a P cross
What are monohybrids?
When the true-breeding parents differ with regard to a single trait to their F1 offspring
What is the F2 generation?
F1 monohybrids to self-fertilize producing a generation
What are dominants?
the displayed trait
What are recessive?
a trait that is masked by the presence of a dominant trait
What are genes?
genetic determinants of traits
What are alleles?
the gene for each trait has 2 variant forms
What does segregate mean?
separate from each other so that each sperm or egg carries only one allele
What is Mendel’s law of segregation?
The idea that the two copies of a gene segregate from each other during transmission from parent to offspring
What is a genotype?
the genetic composition of an individual
What is a homozygous individual?
an individual with two identical copies of a gene
What is a heterozygous individual?
carries 2 different alleles of the same gene
What is a phenotype?
refers to the physical characteristics of an organisms which are the result of the expression of its genes
What are point-shift mutations?
exchange a single nucleotide for another
What are frameshift mutations?
involves the addition or deletion of nucleotides
What are genotype frequencies? What are the allele and genotype frequency
genotypes in a population; allele frequency: number of copies of a specific allele in a population/ total number of all alleles for that gene in a population; genotype frequency: number of individuals with a particular genotype in a population/ total number of individuals in a population
What is the Hardy-Weinberg equation?
(p+q)^2=1
What is inbreeding?
mating between closely related relatives, increases the chances of both parents carrying the same harmful alleles and thus of the production of homozygous offspring that exhibit the effects
The better-adapted organism acquires more resources and leaves more offspring than a less-well-adapted organism. This idea best conveys the theme of:
Natural selection
The theory of evolution by natural selection was proposed by:
Charles Darwin and Alfred Wallace
The color change that has occurred in certain populations of the peppered moth, Biston betularia in industrial areas of Europe is known as:
Industrial melanism
The first generation offspring of true-breeding parents are termed the:
P generation
The 2 variant forms of a gene are called:
Alleles
Which term refers to the genetic composition of an individual?
Gentype
When a chromosome breaks in 2 places and the middle segment turns around and re-fuses with the other 2 pieces, this is termed:
Inversion
What is the expected F2 genotypic ratio of a monohybrid cross?
3:1
Approximately what percentage of genetic variation remains in a population of 25 individuals after 3 generations?
94
Small populations are threatened by the loss of genetic diversity from:
Genetic drift
