| Term | Definition |
|---|
| species | most often characterized by their physical form of morphology, although differences in physiology, biochemistry, behavior, and genetics support the existence of distinct species |
| biological species concept | defines a species as a population/group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with members of other populations |
| reproductive isolation | the existence of biological factors (barriers) that impepde members of two species from producing viable, fertile hybrids |
| prezygotic barriers | immpede mating between species or hinder the fertilization of ova when members of different species attempt to mate |
| postzygotic barriers | if a sperm cell form one species overcomes prezygotic barriers and fertilizes ana ovum from another species, _________ _________ often prevent the hybrid from developing into a viable, fertile adult |
| morphological species concept | characterizes a species by its body shape, size, and other structural features |
| paleontological species concept | focuses on morphologically discrete species known only from the fossil record |
| ecological species concept | views a species in terms of its ecological nich, its rule in a biological community |
| phylogenetic species concept | defines a species as a set of organisms with a unique genetic history |
| allopatric speciation | gene flow is interrupted with a population is divided into geographically isolated subpopulations |
| sympatric speciation | speciation takes place in geographically overlapping populations |
| polyploidy | some plant species have their origins in accidents during cell division that result in extra sets of chromosomes |
| autopolyploidy | an ___________ is an individual that has more than 2 sets of chromosomes, all derived from a single species |
| allopolyploid | in subsequenc generations, various mechanisms can change a sterile hybrid into a fertile polypolidy known as an _______________ |
| adaptive radiation | the evolution of of many diversely adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges is called____________ _________ |
| punctuated equilibrium | in evolutionary theory, long periods of no change interrupted by relatively brief periods of sudden change |
| heterochrony | an evolutionarya change in the rate or timing of developmental events |
| allometric growth | the variation in the relative rates of growth of various parts of the body, which help shape an organism |
| paedomorphosis | if reproductive development accelerates compared to somatic development, the sexually mature stage of a species may retain body features that were juvenile structures in an ancestral species |
| homeotic genes | _______ ______ determine such basic features as where a pair of wings and a pair of legs will develop on a bird |
| Hox genes | the products of one class of homeotic genes, called ______ _______, provide positional information in an animal embryo |
| species selection | a theory maintaining that species living the longest and generating the greatest number of species to determine the direction of major evolutionary trends |
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