Term
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Definition
| - evolutionary change that occurs above the species level |
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Term
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Definition
- The accumulation of changes that gradually transform a given species into a species with different characteristics
- also called phyletic evolution |
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Term
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Definition
| - the splitting of a gene pool into two or more separate pools, which each give rise to one ore more new species |
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| The Biological Species Concept |
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Definition
- defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are unable to produce viable, fertile offspring with members of other populations
**no good for asexual organisms** |
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Term
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Definition
| - the existence of biological factors (barriers) that impeded members of two species from producing viable, fertile hybrids |
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Term
| Types of Reproductive Isolation (2): |
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Definition
1. Prezygotic Barriers
2. Postzygotic Barriers |
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Term
| Definition of Prezygotic Barriers |
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Definition
| - these barriers impede mating between species or hinder the fertilization of ova if members of different species attempt to mate |
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Term
| Definition of Postzygotic Barriers |
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Definition
| = these barriers prevent hybrid zygotes from developing into viable, fertile adults even when a sperm cell from one species does overcome prezyogtic barriers and fertilizes an ovum from another species |
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Term
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Definition
1. Habitat Isolation
2. Temporal Isolation
3. Behavioral Isolation
4. Mechanical Isolation
5. Gametic Isolation |
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Term
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Definition
1. Reduced Hybrid Viability
2. Reduced Hybrid Fertility
3. Hybrid Breakdown |
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Term
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Definition
- two species that occupy different habitats withing the same area may encounter each other rarely, if at all, even though they are not isolated by obvious physical barriers such as mountain ranges
example: two species of garter snakes occur in the same geographic areas but one lives mainly in water while the other is primarily terrestrial |
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Term
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Definition
- species that breed during different times of the day, different seasons, or different years cannot mix their genes
example: In North America, the geographic ranges of the eastern spotted skunk and the western spotted skunk overlap, but the former mates in late winter and the latter mates in late summer |
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Term
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Definition
- courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species
example: Blue-footed boobies, inhabitants of the Galapagos, mate only after a courtship display unique to their species |
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Term
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Definition
- morphological differences can prevent successful mating
example: even in closely related species of plants, the flowers often have distinct appearances that attract different pollinators. Thus, cross-pollination between the plants does not occur. |
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Term
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Definition
| - sperm of one species may not be able to fertilize the eggs of another species. Many mechanisms can produce this isolation. For instance, sperm may not be able to survive in the reproductive tract of females of the other species, or biochemical mechanisms may prevent the sperm from penetrating the membrane surrounding the other species' eggs. |
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Term
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Definition
- the genes of different parent species may interact and impair the hybrid's development
example: some salamander subspecies live in the same regions and habitats, where they may occasionally hybridize. Most of the hybrids do not complete development and those that do are frail |
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Term
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Definition
Even if hybrids are vigorous, they may be sterile. If chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. Since the infertile hybrids cannot produce offspring when they mate with either parental species, genes cannot flow freely between the species
example: the hybrid offspring of a donkey and a horse, a mule, is robust but sterile |
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Term
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Definition
Some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile
example: something about plants |
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Term
| Morphological Species Concept |
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Definition
- characterizes a species by its body shape, size, and other structural features
- useful in the field
- asexual or sexual populations
- relies on subjective criteria |
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Term
| Paleontological Species Concept |
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Definition
- focuses on morphologically discrete species known only from the fossil record
- forced to use fossils when there is little or no information about their mating capability |
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Term
| Ecological Species Concept |
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Definition
| - views a species in terms of its ecological niche, its role in a biological community |
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Term
| Phylogenetic Species Concept |
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Definition
| - defines a species as a set of organisms with a unique genetic history (one branch of the tree of life) |
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Term
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Definition
- gene flow is interrupted when a population is divided into geographically isolated subpopulations
- once geographic separation has occurred, the separated gene pools diverge through any or all of the evolutionary mechanisms
- small, isolated populations are the most likely to undergo allopatric speciation |
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Term
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Definition
- speciation takes place in geographically overlapping populations
- mechanisms include chromosomal changes and nonrandom mating that reduces gene flow |
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Term
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Definition
- a mutational change that results in extra sets of chromosomes
- causes instant sympatric speciation |
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Term
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Definition
| - an individual that has more than two chromosome sets, all derived from a single species |
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Term
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Definition
| - when two different species interbreed and produce a hybrid - if the hybrid can propogate itself asexually (plants), subsequent generations may change a sterile hybrid into a fertily polyploid |
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Term
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Definition
- a type of sympatric speciation
- occurs when genetic factors enable a subpopulation to exploit a resource not used by the parent population
example: maggot flies that once inhabited hawthorn trees but some colonized to apple trees |
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Term
| Sexual Selection (sympatric speciation) |
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Definition
| - think of the red fish and the blue fish and blue fish mate with blue fish and red fish mate with red fish. when they can't see the colors, they mate with anyone -- creates a reproductive barrier |
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Term
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Definition
- the evolution of many diversely adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges
- occurs when a few organisms make their way to new, often distant areas or when environmental changes cause numerous extinctions, opening up ecological niches for the survivors
example: Hawaiian archipelago |
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Term
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Definition
- periods of stasis abruptly interupted by sudden change
- the periods of change are super short compared to the periods of stasis |
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Term
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Definition
- an evolutionary change in the rate or timing of developmental events
example: an organism's shape depends in part on the relative growth rates of different body parts during development |
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Term
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Definition
| - the proportioning that helps give a body its specific form |
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Term
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Definition
- if reproductive development accelerates compared to somatic development, the sexually mature stage of a species may reatin body features that were juvenile structures in an ancestral species
example: domesticated dogs have juvenile features compared to ancesteral wolves |
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Term
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Definition
- genes that control the placement and spatial organization of body parts
- includes HOX genes |
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Term
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Definition
- provide positional information in an animal embryo
- changes in hox genes and in the genes that regulate them can have a profound impact on morphology |
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Term
| Hallmarks of Evolution (5) |
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Definition
– Not goal oriented
– Not equivalent to progress from simple to complex
– Novel features often involve intermediate stages
– Features recycled for different uses
– Baggage often left behind |
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