Chapter 10: Population Genetics and Evolution Flashcards
evolution
the change in a population’s gene pool from one generation to the next
quantitative characteristics
traits in a population that vary along a continuum
gene pool
all the collective genes of a population
population
all the members of the same species within a given area
non-evolving population
a hypothetical collection of individuals in a given area whose gene pool does not change from generation to generation
genotype
the allelic composition for a particular trait
alleles
different forms of a given gene
homozygous
having two identical alleles for a given trait
Tay-Sachs disease
a genetically based disease characterized by a dysfunctional enzyme that fails to break down brain lipids, and is expressed in the homozygous recessive condition
sickle-cell anemia
a disease characterized by defective red blood cells that are inefficient in carrying oxygen
microevolution
changes in genetic structure (genotype) of a population
genetic drift
changes in the gene pool of a small population due to chance
mutation
a change in an organism’s DNA that can result in a permanent change in the allele
natural selection
differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment
gene flow
changes in the gene pool due to migration of fertile individuals or gametes
non-random mating
when an individual chooses a mate based on specific criteria
polymorphism
the occurrence of two or more distinct forms of members of a population
dimorphism
two different morphs
stabilizing selection
extremes are selected against, and the average is selected for
directional selection
one extreme is selected for, and the opposite extreme is selected against
diversifying selection
extremes are selected for, and the average is selected against
natural selection
the process where organisms of differing phenotypes interact with their environment which results in differential reproductive success
biological species concept
two organisms are in the same species when they can produce fertile, viable offspring in free-ranging conditions
morphological species concept
classifies species based on anatomical differences
recognition species concept
classifies species based upon their courtship rituals (genetic, morphological, and behavioral) and mate selection
cohesion species concept
classifies species based upon the mechanisms they use to maintain the phenotypic integrity of the population (ex: reproductive barriers such as pre and post-zygotic isolation)
polyploid
having more than two complete sets of chromosomes (2n)
ecological species concept
classifies species based on their ecological niche or role in the environment (where they live, what they do, and how they look)
allopatric speciation
physical isolation resulting from a geographic barrier separates a splinter population from a main population
marsupial
mammals characterized by embryonic development in a pouch
placental
mammals characterized by embryonic development in a uterus
adaptive radiation
a great increase in species diversity over a relatively short time, each variation adapting to a new or unused resources or habit
sympatric speciation
formation of a new species from a subpopulation while physically located amongst the parent population
autopolyploidy
having more than 2n sets of chromosomes, all of which derived from the same species, and can occur through self-fertilization
nondisjunction
a mistake during cell division in which either pairs of homologous chromosomes or sister chromatids fail to separate properly
allopolyploidy
having more than 2n sets of chromosomes which are derived from two different species
meiotic errors
mistakes that occur during gamete formation that result in cells with an incorrect number of chromosomes
transition fossils
preserved, extinct life forms that show the link between a new species and its parent species
balanced polymorphism
the ability of natural selection to promote diversity in a population
