Chapter 5: Adaptation and Natural Selection Flashcards
Differential success (reproduction and survival) of individuals that results in elimination of maladaptive traits from a population
natural selection
A genetically determined characteristic (behavioral, morphological, or physiological) that improves an organism’s ability to survive and reproduce under prevailing environmental conditions
adaptation
Genetic contribution by an individual’s descendants to future generations
fitness
Unit material of inheritance
More specifically, a small unit of a DNA molecule, coded for a specific protein to produce one of the many attributes of a species
genes
One of two or more alternative forms of a gene that occupies the same relative position or locus on homologous chromosomes
alleles
The environmental cause of fitness differences among organisms within a population with difference phenotypes
selective agent
The phenotypic trait that natural selection acts directly upon
target of selection
Selection favoring individuals at one extreme of the phenotype in a population
directional selection
Selection favoring the middle in the distribution of phenotypes
stabilizing selection
Selection in which two extreme phenotypes in the population leave more offspring than the intermediate phenotype, which has lower fitness
disruptive selection
When individuals choose mates nonrandomly with respect to their genotype, or more specifically, select mates based on some phenotypic trait
assortative mating
Occurs when mates are phenotypically less similar to each other than expected by chance
negative assortative mating
Occurs when mates are phenotypically more similar to each other than expected by chance
positive assortative mating
Mating among close relatives
inbreeding
Random fluctuation in allele frequency over time, due to chance alone without any influence by natural selection
Important in small populations
genetic drift
A measurable, gradual change over a geographic region in the average of some phenotypic character, such as size or coloration
Or it can be a gradient in genotypic frequency
cline
Groups of populations that are semi-isolated from one another by some extrinsic barrier
Compare subspecies
geographic isolate
Subspecies or race adapted to a particular set of environmental conditions
ecotype
Geographical unit of a species population, distinguishable by morphological, behavioral, or physiological characteristics
subspecies
Evolution from a common ancestor of divergent forms adapted to distinct ways of life
adaptive radiation
Ability to change form under different environmental conditions
phenotypic plasticity
The set of phenotypes expressed by a single genotype across a range of environmental conditions
norm of reaction
Differences in phenotypic traits for a given genotype under different environmental conditions that reflect differences in the allocation of biomass to different tissues (leaves, stem, and roots) during the growth and development of the individual plant
developmental plasticity
Reversible phenotypic changes in an individual organism in response to changing environmental conditions—a form of phenotypic plasticity
acclimation
Let’s talk about trade-offs and constraints
“…the fitness of any phenotype is a function of the prevailing environmental conditions; the characteristics that maximize the fitness of an individual under one set of environmental conditions generally limit its fitness under a different set of conditions.”
“The limitations on the fitness of a phenotype under different environmental conditions are a function of trade-offs imposed by constraints that can ultimately by traced to the laws of physics and chemistry.”
“The characteristics enabling a species to survive, grow, and reproduce under one set of conditions limit its ability to do equally well under different environmental conditions.”
The process of directly altering an organism’s genome
genetic engineering
