Chapter 2 Flashcards
Spandrels
Incidental nonadaptive by-products (belly-button)
Exaptations
evolved to do one thing, but now do something else (bird wings)
Homologous structures
similar structures due to a common evolutionary origin
Analogous structures
similar structures without a common origin
Convergent evolution
The evolution of similar solutions to the same environmental demands by unrelated species
Dichotomous traits
Occur in one form or the other, never in combination
True-breeding lines
Interbred members always produce offspring with the same trait
Phenotype
Observable traits
Genotype
traits present in genes
Gene
Inherited factor
Alleles
2 genes that control the same trait
Homozygous
2 identical alleles (BB,ww)
Heterozygous
2 different alleles (Bw)
Meiosis
a process of cell division that yields cells with just 23 chromosomes
Mitosis
a form of cell division that yields daughter cells that have 23 pairs of chromosomes
Linkage
the tendency of traits encoded on the same chromosome to be inherited together
Crossing-over
Increasing diversity, “shuffles the genetic deck”
Female chromosone
XX
Male chromosome
XY
Sex-linked traits
influenced by genes on the sex chromosomes
Phenylketonuria
Single-gene metabolic disorder
