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BIO 152 Test 2
Part 1 Chapter 24
| Question | Answer |
|---|---|
| Speciation | the origin of new species, is at the focal point of evolutionary theory |
| Evolutionary theory | must explain how new species originate and how populations evolve |
| Microevolution | consists of adaptations that evolve within a population, confined to one gene pool |
| Macroevolution | refers to evolutionary change above the species level |
| Biological species concept | states what a species is; is based on the potential to interbreed rather than on physical similarity |
| Species | Latin word meaning “kind” or “appearance”; a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed with other populations |
| Gene flow | holds the phenotype of a population together between populations |
| Reproductive isolation | the existence of biological factors (barriers) that impede two species from producing viable, fertile, offspring |
| Hybrids | the offspring of crosses between different species |
| Prezygotic barriers | block fertilization from occurring by 1. Impeding different species from attempting to mate 2. Preventing the successful completion of mating 3. Hindering fertilization if mating is successful |
| Habitat isolation | two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers |
| Temporal isolation | species that breed at different times of the day, different seasons, or different years cannot mix their gametes |
| Behavioral isolation | courtship rituals and other behaviors unique to a species are effective barriers |
| Mechanical isolation | morphological differences can prevent successful mating |
| Gametic isolation | sperm of one species may not be able to fertilize eggs of another species |
| Postzygotic barriers | prevent the hybrid zygote from developing into a viable, fertile adult; reduced hybrid viability, reduced hybrid fertility, hybrid breakdown |
| Reduced hybrid viability | genes of the different parent species may interact and impair the hybrid’s development |
| Reduced hybrid fertility | even if hybrids are vigorous, they may be sterile |
| Mule | E. asinus male bred with E. cabellus female |
| Hinny | E. asinus female bred with E. cabellus male |
| Hybrid breakdown | some first-generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile |
| Morphological species concept | defines a species by structural features; it applies sexual and asexual species but relies on subjective criteria |
| Ecological species concept | views a species in terms of its ecological niche; it applies to sexual and asexual species and emphasizes the role of disruptive selection |
| Phylogenic species concept | defines a species as the smallest group of individuals on a phylogenetic tree; it apples to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species |
| Two ways in which speciation can occur | allopatric and sympatric |
| Allopatric speciation | gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations |
| Sympatric speciation | speciation takes place in geographically overlapping populations; can result from the appearance of new ecological niches; can be driven by sexual selection |
| Polyploidy | the presence of extra sets of chromosomes due to accidents during cell division; much more common in plants than animals |
| Autopolyploid | an individual with more than two chromosome sets, derived from one species |
| Allopolyploid | a species with multiple sets of chromosomes derived from different species |
| Punctuated equilibrium | term coined by Niles Eldredge and Stephen Jay Gould to describe periods of apparent stasis punctuated by sudden change |
Created by:
AliRutherford
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